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1
Craven, Matt. "‘Other Spaces’: Constructing the Legal Architecture of a Cold War Commons and the Scientific-Technical Imaginary of Outer Space." European Journal of International Law 30, no. 2 (May 2019): 547–72. http://dx.doi.org/10.1093/ejil/chz024.
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Abstract In this article, I seek to develop the argument that the law of outer space, as it was to be developed during the 1960s and 1970s, configured outer space as a ‘commons’ in order to displace two prevailing ‘dystopic’ socio-technical imaginaries that were to be associated with the Cold War. One of these was that outer space might become a place of warfare – and, more specifically, a warfare of annihilatory proportions between the two main protagonists of the Cold War; the other, that it might be the object of ‘primitive accumulation’. Drawing upon the work of Herbert Marcuse, I argue that, whilst the nascent code of outer space visibly sought to repress both of these possibilities, it did so by bringing into play a particular ‘technological rationality’, in which each of these aversions were to reappear as sustaining configurations – as what might be called the rational irrationalities of a Cold War commons.
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Machado, Álvaro Manuel. "Culto do lúdico, heteronímia e espírito do lugar em Mário Cláudio / Worship of the playful, heteronomy and spirit of the place in Mario Cláudio." Revista do Centro de Estudos Portugueses 38, no. 59 (November 1, 2018): 11. http://dx.doi.org/10.17851/2359-0076.38.59.11-21.
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Resumo: Análise do romance Tiago Veiga – uma biografia, a partir de uma reflexão sobre o imaginário do espaço portuense e minhoto, concentrada predominantemente na metáfora da casa. Palavras-chave: imaginário; ficção portuguesa contemporânea; Mário Cláudio.Abstract: Analysis of the novel Tiago Veiga – a biography, based on the consideration of the imaginary that the regions of Porto and Minho carry, focused mainly on the metaphor of the house.Keywords: Imaginary; Contemporary Portuguese Fiction; Mario Claudio.
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CLEGG, E. J., T. J. RINGROSE, and J. F. CROSS. "SOME FACTORS AFFECTING MARITAL DISTANCES IN THE OUTER HEBRIDES." Journal of Biosocial Science 30, no. 1 (January 1998): 43–62. http://dx.doi.org/10.1017/s0021932098000431.
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Some factors affecting marital distances have been studied in two Outer Hebridean islands, Harris (843 marriages) and Barra (444 marriages), over the period 1855-1990. In each island marital distances fell before 1900, but then rose to their greatest values after the 1950s. Fishermen generally married at the shortest distances and men in land-based occupations at the longest. The depression in the fishing industry during the 1880s and early 1890s was associated with reductions in marital distances, especially among fishermen. In the different regions of Harris, marital distances were least in the south-east, where settlement was most dense, and greatest in the south-west where it was most sparse.When the association between marital frequencies and inter-settlement distances was studied, it was found that for Harris there was, overall, a trend to endogamous and short-distance marriage. However, this trend was only slight during 1955-90. For Barra a similar trend was found before 1955, but thereafter there appeared to be virtually no connection between marital frequency and inter-settlement distance. Thus the only constraint on marriage was the spatial distribution of settlements. In this situation the chances of random mating with respect to distance are maximised.Application of ‘Central Place’ theory suggested that only since 1946 can any tendency be detected to regard Tarbert in Harris or Castlebay in Barra as Central Places, at least as far as marriage is concerned. In each island the tendency appears to be limited to the settlements closest to the Central Place.
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López Fernández, R., R. M. González Delgado, E. Pérez, R. García-Benito, R. Cid Fernandes, W. Schoenell, S. F. Sánchez, et al. "Cosmic evolution of the spatially resolved star formation rate and stellar mass of the CALIFA survey." Astronomy & Astrophysics 615 (July 2018): A27. http://dx.doi.org/10.1051/0004-6361/201732358.
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We investigate the cosmic evolution of the absolute and specific star formation rate (SFR, sSFR) of galaxies as derived from a spatially resolved study of the stellar populations in a set of 366 nearby galaxies from the Calar Alto Legacy Integral Field Area (CALIFA) survey. The sample spans stellar masses from M⋆ ~ 109 to 1012M⊙ and a wide range of Hubble types. The analysis combines images obtained with the Galaxy Evolution Explorer (GALEX; far-ultraviolet and near-ultraviolet) and Sloan Digital Sky Survey (SDSS; u, g, r, i, z) with the 4000 Å break, Hβ, and [MgFe]′ indices measured from the CALIFA data cubes to constrain parametric models for the star formation history (SFH), which are then used to study the cosmic evolution of the SFR density (ρSFR), the sSFR, the main sequence of star formation (MSSF), and the stellar mass density (ρ⋆). Several SFH laws are used to fit the observational constrains. A delayed-τ model, SFR ∝ (t0 − t)exp(−(t0 − t)∕τ), provides the best results, in good agreement with those obtained from cosmological surveys. Our main results from this model are that (a) the mass currently in the inner (≤0.5 half-light radius, HLR) regions formed at earlier epochs than the mass in the outer (1–2 HLR) regions of galaxies. The time since the onset of the star formation is longer in the inner regions (t0 ~ 13−10 Gyr) than in the outer ones (t0 ~ 11−9 Gyr) for all the morphologies, while the e-folding timescale τ in the inner region is similar to or shorter than in the outer regions. These results confirm that galaxies of any Hubble type grow inside-out. (b) The sSFR declines rapidly as the Universe evolves, and faster for early- than for late-type galaxies, and for the inner than for the outer regions of galaxies. (c) The evolution of ρSFR and ρ⋆ agrees well with results from cosmological surveys, particularly with the recent results from the Galaxy And Mass Assembly (GAMA), the G10-Cosmological Evolution Survey (COSMOS), and the 3D Hubble Space Telescope (HST) survey. At low redshift, z ≤ 0.5, most star formation takes place in the outer regions of late spiral galaxies, while at z > 2, the inner regions of the progenitors of the current E and S0 are the main contributors to ρSFR. (d) Similarly, the inner regions of galaxies are the main contributor to ρ⋆ at z > 0.5, growing their mass faster than the outer regions, with a lookback time at 50% ρ⋆ of t50 ~ 9 and 6 Gyr for the inner and outer regions. (e) The MSSF follows a power law at high redshift, with the slope evolving with time but always remaining sub-linear, in good agreement with the Illustris simulation. (f) In agreement with galaxy surveys at different redshifts, the average SFH of CALIFA galaxies indicates that galaxies grow their mass mainly in a mode that is well represented by a delayed-τ model, with the peak at z ~ 2 and an e-folding time of ~3.9 Gyr.
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AGRAWAL, MAMTA, NEERU ADLAKHA, and K. R. PARDASANI. "FINITE ELEMENT MODEL TO STUDY THERMAL EFFECT OF UNIFORMLY PERFUSED TUMOR IN DERMAL LAYERS OF ELLIPTICAL SHAPED HUMAN LIMB." International Journal of Biomathematics 04, no. 02 (June 2011): 241–54. http://dx.doi.org/10.1142/s1793524511001362.
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In this paper, a two-dimensional finite element model has been developed to study thermal disturbances in elliptical shaped human limbs involving uniformly perfused tumor. The model incorporates the effect of important physiological parameters like blood mass flow rate, self-controlled metabolic activity and thermal conductivity in dermal regions. For tumor regions the uncontrolled rate of metabolic activity and abnormal rate of blood flow have been incorporated. The outer surface of the limb is exposed to the environment where heat loss takes place via the conduction, convection, radiation and evaporation. Appropriate boundary conditions have been framed. The model has been simulated using MATLAB 7.5 to obtain numerical results.
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Curir, Anna, Giuseppe Murante, Eva Poglio, and Álvaro Villalobos. "The dual nature of the Milky Way stellar halo." Proceedings of the International Astronomical Union 6, S271 (June 2010): 145–52. http://dx.doi.org/10.1017/s1743921311017558.
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AbstractThe theory of the Milky Way formation, in the framework of the ΛCDM model, predicts galactic stellar halos to be built from multiple accretion events starting from the first structure to collapse in the Universe.Evidences in the past few decades have indicated that the Galactic halo consists of two overlapping structural components, an inner and an outer halo. We provide a set of numerical N-body simulations aimed to study the formation of the outer Milky Way (MW) stellar halo through accretion events between a (bulgeless) MW-like system and a satellite galaxy. After these minor mergers take place, in several orbital configurations, we analyze the signal left by satellite stars in the rotation velocity distribution. The aim is to explore the orbital conditions of the mergers where a signal of retrograde rotation in the outer part of the halo can be obtained, in order to give a possible explanation of the observed rotational properties of the MW stellar halo.Our results show that the dynamical friction has a fundamental role in assembling the final velocity distributions originated by different orbits and that retrograde satellites moving on low inclination orbits deposit more stars in the outer halo regions and therefore can produce the counter-rotating behavior observed in the outer MW halo.
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Feast, M. W. "Post-AGB Variables and Stellar Mass-Loss." Symposium - International Astronomical Union 177 (2000): 207–16. http://dx.doi.org/10.1017/s0074180900002424.
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A brief review is given of the various types of star which are thought to be in the immediate post-AGB stage of evolution. The paper then concentrates on the properties of the RCB stars and particularly on the mass-loss process in these stars. It is suggested that grain formation takes place over the cool regions of giant convection cells in a super-Eddington outflow and in the form of small clouds or puffs. Attention is drawn to observations which suggest that grain formation in the outer atmospheres of Miras and other cool giants may also take place in puffs rather than in spherical shells. Evidence on the long-term variation of the circumstellar dust emission from RCB stars is summarized.
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Gerhard, Ortwin. "Star Formation in Virgo Intracluster Space." Symposium - International Astronomical Union 217 (2004): 480–85. http://dx.doi.org/10.1017/s0074180900198237.
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A number of candidate isolated compact HII regions have been discovered on combined Hα, [OIII], and broadband images in the Virgo cluster. One point-like source was spectroscopically confirmed as an HII region; this object is powered by a small starburst with an estimated mass of ~ 400 M⊙ and age of ~ 3 Myr. The object is located in the diffuse outer halo of NGC 4388, or could possibly be in intracluster space. Several resolved HII candidates are seen in the extended (~ 35 kpc) emission line region north-east of NGC 4388, perhaps triggered by the jet from the galaxy's nucleus. Star formation can thus take place far outside the main star forming regions of galaxies. The origin of the gas, the star formation, and some implications are discussed.
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Makrariya, Akshara, and Neeru Adlakha. "Two-dimensional finite element model to study temperature distribution in peripheral regions of extended spherical human organs involving uniformly perfused tumors." International Journal of Biomathematics 08, no. 06 (October 15, 2015): 1550074. http://dx.doi.org/10.1142/s1793524515500746.
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Temperature as an indicator of tissue response is widely used in clinical applications. In view of above a problem of temperature distribution in peripheral regions of extended spherical organs of a human body like, human breast involving uniformly perfused tumor is investigated in this paper. The human breast is assumed to be spherical in shape with upper hemisphere projecting out from the trunk of the body and lower hemisphere is considered to be a part of the body core. The outer surface of the breast is assumed to be exposed to the environment from where the heat loss takes place by conduction, convection, radiation and evaporation. The heat transfer from core to the surface takes place by thermal conduction and blood perfusion. Also metabolic activity takes place at different rates in different layers of the breast. An elliptical-shaped tumor is assumed to be present in the dermis region of human breast. A finite element model is developed for a two-dimensional steady state case incorporating the important parameters like blood flow, metabolic activity and thermal conductivity. The triangular ring elements are employed to discretize the region. Appropriate boundary conditions are framed using biophysical conditions. The numerical results are used to study the effect of tumor on temperature distribution in the region.
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Broad, Amanda J., and Jennifer G. DeLuca. "The right place at the right time: Aurora B kinase localization to centromeres and kinetochores." Essays in Biochemistry 64, no. 2 (May 14, 2020): 299–311. http://dx.doi.org/10.1042/ebc20190081.
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Abstract The fidelity of chromosome segregation during mitosis is intimately linked to the function of kinetochores, which are large protein complexes assembled at sites of centromeric heterochromatin on mitotic chromosomes. These key “orchestrators” of mitosis physically connect chromosomes to spindle microtubules and transduce forces through these connections to congress chromosomes and silence the spindle assembly checkpoint. Kinetochore-microtubule attachments are highly regulated to ensure that incorrect attachments are not prematurely stabilized, but instead released and corrected. The kinase activity of the centromeric protein Aurora B is required for kinetochore-microtubule destabilization during mitosis, but how the kinase acts on outer kinetochore substrates to selectively destabilize immature and erroneous attachments remains debated. Here, we review recent literature that sheds light on how Aurora B kinase is recruited to both centromeres and kinetochores and discuss possible mechanisms for how kinase interactions with substrates at distinct regions of mitotic chromosomes are regulated.
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Kirchoff, Bruce K. "Inflorescence and flower development in the Hedychieae (Zingiberaceae): Hedychium." Canadian Journal of Botany 75, no. 4 (April 1, 1997): 581–94. http://dx.doi.org/10.1139/b97-065.
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Flower organogenesis in Hedychium gardnerianum and Hedychium coronarium begins with the sequential formation of the sepals on a rounded–triangular apex. Growth in three regions of the apex, inside the sepals, produces three common petal – inner androecial primordia. Intercalary growth below and between these primordia produces a floral cup, the site of gynoecial formation. The common primordia separate to form petals and inner androecial members. After separation, the anterior inner androecial members fuse to form the labellum. The posterior member forms the polleniferous stamen. Up to this point in development, the flowers of H. coronarium are slightly ahead of those of H. gardnerianum. However, in H. gardnerianum, initiation of the two thecae of the stamen occurs immediately following the separation of the common primordia, while thecae formation in H. coronarium is slightly delayed. These results show that the relative timing of developmental events can vary even over a short developmental period. Formation of the outer androecium takes place at the apices of a triangle formed by the inner androecial members. The anterior outer androecial member aborts soon after formation, whereas the posterior outer androecial members form the two petaloid staminodes that are found on the lateral sides of the labellum in the mature flower. Key words: flower development, flower structure, inflorescence, stamen, Zingiberaceae, Hedychium.
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GWINN, ALLAN W., and S. J. JACOBS. "Mass transport in viscous flow under a progressive water wave." Journal of Fluid Mechanics 340 (June 10, 1997): 61–82. http://dx.doi.org/10.1017/s002211209700520x.
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We consider two-dimensional free surface flow caused by a pressure wavemaker in a viscous incompressible fluid of finite depth and infinite horizontal extent. The governing equations are expressed in dimensionless form, and attention is restricted to the case δ[Lt ]ε[Lt ]1, where δ is the characteristic dimensionless thickness of a Stokes boundary layer and ε is the Strouhal number. Our aim is to provide a global picture of the flow, with emphasis on the steady streaming velocity.The asymptotic flow structure near the wavenumber is found to consist of five distinct vertical regions: bottom and surface Stokes layers of dimensionless thickness O(δ), bottom and surface Stuart layers of dimensionless thickness O(δ/ε) lying outside the Stokes layers, and an irrotational outer region of dimensionless thickness O(1). Equations describing the flow in all regions are derived, and the lowest-order steady streaming velocity in the near-field outer region is computed analytically.It is shown that the flow far from the wavemaker is affected by thickening of the Stuart layers on the horizontal length scale O[(ε/δ)2], by viscous wave decay on the scale O(1/δ), and by nonlinear interactions on the scale O(1/ε2). The analysis of the flow in this region is simplified by imposing the restriction δ=O(ε2), so that all three processes take place on the same scale. The far-field flow structure is found to consist of a viscous outer core bounded by Stokes layers at the bottom boundary and water surface. An evolution equation governing the wave amplitude is derived and solved analytically. This solution and near-field matching conditions are employed to calculate the steady flow in the core numerically, and the results are compared with other theories and with observations.
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Mollá, M., O. Cavichia, R. D. D. Costa, and W. J. Maciel. "The population of planetary nebulae near the Galactic Centre: chemical abundances." Proceedings of the International Astronomical Union 12, S323 (October 2016): 339–40. http://dx.doi.org/10.1017/s1743921317001685.
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AbstractIn this work, we report physical parameters and abundances derived for a sample of 15 high extinction planetary nebulae located in the inner 2° of the Galactic bulge, based on low dispersion spectroscopy secured at the SOAR telescope using the Goodman spectrograph. The new data allow us to extend our database including older, weaker objects that are at the faint end of the planetary nebulae luminosity function. The data provide chemical compositions for PNe located in this region of the bulge to explore the chemical enrichment history of the central region of the Galactic bulge. The results show that the abundances of our sample are skewed to higher metallicities than previous data in the outer regions of the bulge. This can indicate a faster chemical enrichment taking place at the Galactic centre.
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Yu, Cheng-Ku, and Ying Chen. "Surface Fluctuations Associated with Tropical Cyclone Rainbands Observed near Taiwan during 2000–08." Journal of the Atmospheric Sciences 68, no. 8 (August 1, 2011): 1568–85. http://dx.doi.org/10.1175/2011jas3725.1.
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Abstract With radar measurements and temporally high-resolution surface observations, this study investigates surface fluctuations associated with tropical cyclone rainbands (TCRs) observed in the vicinity of Taiwan during 2000–08. A total of 263 TCRs identified from 37 typhoon events during the study period were analyzed to show the mean and common nature of perturbations of various meteorological variables associated with the passage of TCRs. The main patterns of surface thermodynamic fluctuations, as revealed from the composite analysis of all identified TCRs, include a persistent decrease in temperature, dewpoint temperature, and equivalent potential temperature θe from the outer to inner edge of the rainband. A wavelike variation of pressure perturbations associated with the rainband was evident, with a minimum coincident with the outer edge and a maximum located inside the inner edge. The kinematics of the rainband was characterized by an obvious decrease in cross-band wind component, relatively minor variations in along-band wind component, and the wind veering. Quantitative analyses indicate that the majority of the TCRs (~80%–90%) exhibited variations in surface temperature, pressure, wind speed, and wind direction less than 2°C, 1.5 mb, 5 m s−1, and 20°, respectively. However, a clear trend of the magnitude of TCR thermodynamic fluctuations increasing with the radial distance from the tropical cyclone center was observed. The TCRs identified in this study were also classified into the outer and inner rainbands, which are distinguished by a radial distance of 3 times the radius of maximum wind. The composite and magnitude analyses of their surface fluctuations indicate that the outer rainbands had a higher potential than the inner rainbands to reduce the near-surface θe values. This observed characteristic is likely related to more pronounced evaporative cooling taking place in drier subcloud regions and the downward transport of low-θe air aloft by more vigorous convective downdrafts for the outer rainband. Fundamentally different features of surface pressure fluctuations and mean frictional vertical velocity and relative vorticity between the outer and inner rainbands were also documented. These results reflect a possibly different origin. Nevertheless, there was no dramatic difference in the pattern of kinematic fluctuations between the outer and inner rainbands, and their mean magnitudes were also found to be statistically identical, which suggests that there is not an entirely clear distinction of surface characteristics for these two types of rainbands.
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Gunnarsson, Britt-Louise. "Multilingualism in the Workplace." Annual Review of Applied Linguistics 33 (March 2013): 162–89. http://dx.doi.org/10.1017/s0267190513000123.
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This survey article presents studies on multilingualism in the workplace carried out in different regions. One aim is to give a cross-cultural picture of workplace studies on different languages, and another is to discuss both positive and problem-based accounts of multilingualism at work. The conditions for workplace discourse have been influenced by a series of changes taking place in recent decades. Technological advances have led to new types of networks and workplaces, making linguistic issues salient, at the same time as many low-paid workers are found in traditional jobs, for which the face-to face interaction is central. A model is presented, the aim of which is to grasp the complex and dynamic interplay between workplace discourse and its various contextual frames. Overviews of studies on multilingualism at work are discussed with a focus on workplaces in the inner, outer, and expanding English circles; in transnational companies; and in multilingual regions and English lingua franca workplaces in Europe. Workplaces with workforce diversity are also dealt with. In the discussion section, the scope is enlarged and workplace discourse is related to various contextual frameworks. Finally, some key topics for future studies are sketched.
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Di Matteo, P., M. Haywood, F. Combes, B. Semelin, C. Babusiaux, and A. Gomez. "Radial migration in barred galaxies." Proceedings of the International Astronomical Union 10, H16 (August 2012): 355. http://dx.doi.org/10.1017/s1743921314011272.
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AbstractIn this talk, I will present the result of high resolution numerical simulations of disk galaxies with various bulge/disk ratios evolving isolated, showing that: •Most of migration takes place when the bar strength is high and decreases in the phases of low activity (in agreement with the results by Brunetti et el. 2011, Minchev et al. 2011).•Most of the stars inside the corotation radius (CR) do not migrate in the outer regions, but stay confined in the inner disk, while stars outside CR can migrate either inwards or outwards, diffusing over the whole disk.•Migration is accompanied by significative azimuthal variations in the metallicity distribution, of the order of 0.1 dex for an initial gradient of ~-0.07 dex/kpc.•Boxy bulges are an example of stellar structures whose properties (stellar content, vertical metallicity, [α/Fe] and age gradients, ..) are affected by radial migration (see also Fig. 1).
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Suga, S. "Enamel Hypomineralization Viewed From the Pattern of Progressive Mineralization of Human and Monkey Developing Enamel." Advances in Dental Research 3, no. 2 (September 1989): 188–98. http://dx.doi.org/10.1177/08959374890030021901.
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Microradiograms and their computer-aided image analysis of ground sections of the developing enamel of human permanent third molars and monkey permanent teeth (Macaca fuscata) indicate that the mode of progressive mineralization of enamel is completely different between the matrix formation and maturation stages. During the former stage, the enamel matrix is slightly mineralized. During the latter stage, which takes a much longer period than the previous stage, the increase in the secondary mineralization takes place first slightly, from the surface toward the inner layer, and then heavily, from the inner layer toward the surface. The narrow outer layer mineralizes very slowly during the middle and late stages of maturation, but finally achieves the highest mineralization of the entire enamel layer. The very narrow innermost layer mineralizes slowly without expanding its width. The former three processes seem to be under the direct control of the ameloblasts. Hypoplastic areas which appear during the matrix formation stages are not necessarily accompanied by hypomineralization. Dysfunction of the cells immediately after the completion of matrix formation appears to cause hypomineralization throughout the entire width of matrix except for the innermost layer. Disorders of the cells occurring during the middle and/or the late stage of maturation—due to chronic metabolic disturbances, such as fluorosis—induced hypomineralization localized mainly at the outer layer. The hypomineralized enamel is not necessarily accompanied by hypoplasia. The process of enamel mineralization is not necessarily fully synchronized with that of tooth eruption. Therefore, the narrow outer layer, especially in the fissure and cervical regions, is sometimes hypomineralized even after the teeth have erupted normally.
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Belenkaya, Elena S., Stanley W. H. Cowley, Igor I. Alexeev, Vladimir V. Kalegaev, Ivan A. Pensionerov, Marina S. Blokhina, and David A. Parunakian. "Open and partially closed models of the solar wind interaction with outer planet magnetospheres: the case of Saturn." Annales Geophysicae 35, no. 6 (December 6, 2017): 1293–308. http://dx.doi.org/10.5194/angeo-35-1293-2017.
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Abstract. A wide variety of interactions take place between the magnetized solar wind plasma outflow from the Sun and celestial bodies within the solar system. Magnetized planets form magnetospheres in the solar wind, with the planetary field creating an obstacle in the flow. The reconnection efficiency of the solar-wind-magnetized planet interaction depends on the conditions in the magnetized plasma flow passing the planet. When the reconnection efficiency is very low, the interplanetary magnetic field (IMF) does not penetrate the magnetosphere, a condition that has been widely discussed in the recent literature for the case of Saturn. In the present paper, we study this issue for Saturn using Cassini magnetometer data, images of Saturn's ultraviolet aurora obtained by the HST, and the paraboloid model of Saturn's magnetospheric magnetic field. Two models are considered: first, an open model in which the IMF penetrates the magnetosphere, and second, a partially closed model in which field lines from the ionosphere go to the distant tail and interact with the solar wind at its end. We conclude that the open model is preferable, which is more obvious for southward IMF. For northward IMF, the model calculations do not allow us to reach definite conclusions. However, analysis of the observations available in the literature provides evidence in favor of the open model in this case too. The difference in magnetospheric structure for these two IMF orientations is due to the fact that the reconnection topology and location depend on the relative orientation of the IMF vector and the planetary dipole magnetic moment. When these vectors are parallel, two-dimensional reconnection occurs at the low-latitude neutral line. When they are antiparallel, three-dimensional reconnection takes place in the cusp regions. Different magnetospheric topologies determine different mapping of the open-closed boundary in the ionosphere, which can be considered as a proxy for the poleward edge of the auroral oval.
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Mironova, I. A., and I. G. Usoskin. "Possible effect of extreme solar energetic particle events of September–October 1989 on polar stratospheric aerosols: a case study." Atmospheric Chemistry and Physics Discussions 13, no. 2 (February 27, 2013): 5411–28. http://dx.doi.org/10.5194/acpd-13-5411-2013.
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Abstract. The main ionization source of the middle and low Earth atmosphere is related to energetic particles coming from outer space. Usually it is ionization from cosmic rays that is always present in the atmosphere. But in a case of a very strong solar eruption some solar energetic particles (SEP) can reach middle/low atmosphere increasing the ionization rate up to some orders of magnitude at polar latitudes. We continue investigating such a special class of solar events and their possible applications for natural variations of the aerosol content. After the case study of the extreme SEP event of January 2005 and its possible effect upon polar stratospheric aerosols, here we analyze atmospheric applications of the second sequence of several events that took place over the Autumn 1989. Using aerosol data obtained over polar regions from two satellites with space-borne optical instruments SAGE II and SAM II that were operating during September–October 1989, we found that an extreme major SEP event might have led to formation of new particles and/or growth of preexisting ultrafine particles in the polar stratospheric region. However, the effect of the additional ambient air ionization on the aerosol formation is minor, in comparison with temperature effect, and can take place only in the cold polar atmospheric conditions.
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Foster, Jeremy. "Archaeology, aviation, and the topographical projection of ‘Paradoxical Modernism’ in 1940s South Africa." Architectural Research Quarterly 19, no. 2 (June 2015): 133–48. http://dx.doi.org/10.1017/s1359135515000214.
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At the time of his premature death in 1942, Rex Martienssen, the gifted South African architect who had helped make Johannesburg an outpost of modernism, had just completed a seminal PhD thesis on Greek space, and was documenting the layout of remote African settlements in South Africa's highlands. Martienssen's writings suggest that the link between these disjunct projects was topographical thinking, a form of architectural seeing and thinking that ontologically articulates time, place and culture. His research project was informed by the white colonial national intellectual search for an alternative to the racialised imaginary geography being promoted by white nationalism in the 1930s, a paradoxical modernity that would be progressive and cosmopolitan, yet also respected a timeless order threatened by European modernity. This re-envisioning of the 'place' of Western culture in Africa was encouraged by two seemingly-unrelated engagements with the sub-continent's terrain: archaeology and commercial aviation. Both practices came into their own in Southern Africa during this period, deploying Western technique and rationality in ways that constructed a vision of the subcontinent that unsettled the territorial limits and historical narratives of the post-colony, and inaugurated perceptions of the African landscape as modern and transcultural, yet situated in the Hegelian geographical movement of history. This made it possible to imagine, for the first time, that the topographical organisation of indigenous settlements might yield a spatial logic for new urban areas. A key figure in understanding this multiscalar geo-historical subjectivity was Le Corbusier, who had close ties with Martienssen and what he called le Groupe Transvaal. Le Corbusier's global journeys during the 1930s had made him increasingly interested in the anthropo-geographic traces left by the 'natural order of things' in human environments, and the possibility of a neo-syndicalist world order based on geo-political regions that were latitudinally complementary.
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Cirtautas, Matas. "CHANGING PERIPHERY OF THE BALTIC CITIES: LITHUANIAN CASE." Journal of Architecture and Urbanism 39, no. 1 (April 14, 2015): 56–69. http://dx.doi.org/10.3846/20297955.2015.1025453.
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Urban sprawl is one of the dominant types of urban development in the world. Although outer growth started from the outset of cities, urban researchers, planners and policy makers are highly concerned about its current extent. Recent development of the Baltic cities and especially trends of their suburban growth have been analysed only partly, because of the relative novelty of the phenomenon and well-established dominance of western cities in the field. This paper attempts to fill this gap and presents a research on conditions and consequences of extensive development of Lithuanian cities. Evidences from the recent growth of the Baltic cities show that decline and sprawl take place simultaneously in major urban regions with possible long-term consequences on their spatial structure. Therefore, this article advocates a need to revise urban policy in the Baltic countries and promote coordinated development of urban and suburban areas in the context of prevailing negative demographic trends and limited capacity of central and local governments to interfere in urban development processes.
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Alharbi, B. H., A. Maghrabi, and N. Tapper. "The March 2009 Dust Event in Saudi Arabia: Precursor and Supportive Environment." Bulletin of the American Meteorological Society 94, no. 4 (April 1, 2013): 515–28. http://dx.doi.org/10.1175/bams-d-11-00118.1.
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A case study is presented of the environmental background for a massive Saudi Arabian dust storm event that took place on 10 and 11 March 2009. The dust storm was large enough to be clearly seen from outer space and caused a widespread heavy atmospheric dust load, very low visibility, total airport shutdown, and damage to vehicles and trees across northern and central parts of Saudi Arabia. The precursor and supportive environment for this dust storm outbreak are investigated, drawing upon routine synoptic data and satellite imagery. Analytical evidence is offered to suggest that this dust storm was triggered and sustained by a cold front passage coincident with the propagation of a preexisting intense upperlevel jet streak. The major plume of the 10 March 2009 dust storm originated from several rich dust source areas extending across two regions—the Qasim region and the Adibdibah and As-Summan Plateau region. The intensity and frequency of dust storms triggered from these active areas of dust emissions seem to be dominated by a response to the amount of precipitation during November and December.
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Hnylko, Oleh, Svitlana Hnylko, Maria Kulyanda, and Romana Marchenko. "Tectonic-sedimentary evolution of the frontal part of the Ukrainian Carpathian nappe structure." Geology and Geochemistry of Combustible Minerals 1-2, no. 183-184 (2021): 45–59. http://dx.doi.org/10.15407/ggcm2021.01-02.045.
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For the first time in the Ukrainian Carpathians, the depths and tectono-sedimentation processes in the north-eastern part of the Outer Carpathian Basin (Skyba and Boryslav-Pokuttya units) have been restored on the base of sedimentological and microfaunistic studies. It was established that in the Cretaceous-Eocene time, the deep-water (near Calcite Compensation Depth) turbidite and similar sedimentation (turbidites with Bouma textures, grainites, debris-flow deposits), which periodically alternated with (hemi)pelagic sedimentation (red, green and black shales) was dominant here. Sedimentation took place on the continental margin of the the Carpathian branch of the Tethys, where deep-water fans were formed. Cretaceous-Eocene background red and green shales are enriched in buried in situ benthic foraminifera which are similar in taxonomic composition and morphological features to the microfauna of the Carpathian-Alpine and Atlantic regions (deep-water agglutinated foraminifera), which indicate lower bathyal – abyssal depths of flysch sedimentation. Latest Eocene Globigerina Marl horizon contains the foraminiferal assemblage with plankton dominance, which indicates a general shallowing of the Outer Carpathian Basin (middle-upper bathyal conditions above a calcite compensation depth). Oligocene – lowermost Miocene Menilite-Krosno and Polyanytsia formations were accumulated in the Skyba and Boryslav-Pokuttya sub-basins. In the Miocene, shallow-water molasses were accumulated here. Probably, the tectonic uproot of flysch deposits from its substrate and their synsedymentary thrusting towards the platform caused a significant shallowing of the Skyba and Boryslav-Pokuttya sub-basins starting from the latest Eocene. These processes reflected the growth of the Carpathian frontal nappes at the final orogen formation stage.
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Mironova, I. A., and I. G. Usoskin. "Possible effect of extreme solar energetic particle events of September–October 1989 on polar stratospheric aerosols: a case study." Atmospheric Chemistry and Physics 13, no. 17 (September 2, 2013): 8543–50. http://dx.doi.org/10.5194/acp-13-8543-2013.
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Abstract. The main ionization source of the middle and low Earth's atmosphere is related to energetic particles coming from outer space. Usually it is ionization from cosmic rays that is always present in the atmosphere. But in a case of a very strong solar eruption, some solar energetic particles (SEPs) can reach middle/low atmosphere increasing the ionization rate up to some orders of magnitude at polar latitudes. We continue investigating such a special class of solar events and their possible applications for natural variations of the aerosol content. After the case study of the extreme SEP event of January 2005 and its possible effect upon polar stratospheric aerosols, here we analyze atmospheric applications of the sequence of several events that took place over autumn 1989. Using aerosol data obtained over polar regions from two satellites with space-borne optical instruments SAGE II and SAM II that were operating during September–October 1989, we found that an extreme major SEP event might have led to formation of new particles and/or growth of preexisting ultrafine particles in the polar stratospheric region. However, the effect of the additional ambient air ionization on the aerosol formation is minor, in comparison with temperature effect, and can take place only in the cold polar atmospheric conditions. The extra aerosol mass formed under the temperature effect allows attributing most of the changes to the "ion–aerosol clear sky mechanism".
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Downing, Leon S., and Robert Nerenberg. "Sustainable nitrogen removal from wastewater with the hybrid membrane biofilm process (HMBP): bench-scale studies." Water Science and Technology 58, no. 9 (November 1, 2008): 1715–20. http://dx.doi.org/10.2166/wst.2008.550.
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The hybrid membrane biofilm process (HMBP) is a novel approach to achieving total nitrogen removal from wastewater. It incorporates air-supplying, hollow-fiber membranes into a conventional activated sludge tank, where bulk aeration is suppressed. A nitrifying biofilm grows on the membranes and exports nitrite and nitrate to the anoxic bulk liquid, where suspended heterotrophic bacteria denitrify using influent BOD as an electron donor. Bench scale tests were used to assess the performance of the HMBP for a variety of nitrogen and BOD loading rates. For a nitrogen loading of 1.6 gN m−2, the nitrification flux remained at approximately 1.0 gN m−2 d−1 for BOD loadings ranging from 4 to 17 gBOD m−2 d−1 day−1. Full denitrification was achieved when sufficient BOD was available in the influent. Microsensor measurements indicated nitrite was the dominant form of oxidized nitrogen produced by the biofilm, showing that shortcut nitrogen removal was taking place. Fluorescence in-situ hybridization (FISH) tests on the biofilm revealed a unique stratification, with three distinct regions: AOB and NOB near the membrane, strictly AOB at intermediate depths, and AOB and heterotrophs at the outer edge of the biofilm.
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Paternò, L. "Internal dynamics and magnetism of the Sun." Highlights of Astronomy 10 (1995): 327–29. http://dx.doi.org/10.1017/s1539299600011382.
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The present internal dynamics and magnetism of the Sun have been determined by the initial conditions in the pre-main sequence age, by the angular momentum loss and its redistribution in the interior, and the interaction of motion with magnetic field.The history of the Sun rotation is traced back by observing the present rotation of stars with the same mass as the Sun at earlier evolutionary stages. The present angular momentum of the Sun, as deduced from its internal rotational behavior derived from helioseismological data, appears to be a small percentage of the original one contained in similar mass stars (T Tauri and α Persei). It is not easy to reconcile the sharp decrease in the surface angular velocity, which follows the α Persei phase, with the subsequent soft decrease, taking place after Pleiades phase, unless some very effective mechanism transfers angular momentum from inner to outer regions, where is lost in the solar wind. Such a mechanism is probably magnetic in origin, since purely hydrodynamic instabilities fail to transfer angular momentum at a rate sufficient to determine the presently observed flat radial gradient of the internal angular velocity.
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Saunders, David. "REGIONAL DIVERSITY IN THE LATER RUSSIAN EMPIRE." Transactions of the Royal Historical Society 10 (December 2000): 143–63. http://dx.doi.org/10.1017/s0080440100000074.
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AbstractWERE tendencies in the direction of regional difference in the later Russian Empire outweighing tendencies in the direction of homogeneity? In view of the fact that the empire fell apart in 1917, it looks as if the emphasis ought to be on difference. A good case, however, can also be made for homogeneity. I shall therefore be proposing that the regions of the Russian Empire occupied a more or less constant position on an imaginary `divergence–coalescence spectrum'. Admittedly, the contest between divergence and coalescence ceased to be equal during the First World War and the empire collapsed. This imbalance, however, turned out to be temporary. The empire re-emerged under a new name at the end of 1922 and for sixty-nine years thereafter occupied more or less the same place on the divergence–coalescence spectrum that it had occupied before it collapsed. So I shall be arguing that, except under extreme duress, the empire was stable. It is this stability I wish to draw to your attention. One's natural inclination is to think of the later Russian Empire as a hotbed of change. I have argued in a recent article that the inclination should be resisted in analyses of work-patterns. I shall argue today that it should also be resisted in the field of regional diversity. To make the case, I shall divide what I have to say into three parts, the first on divergence, the second on coalescence and the third on the First World War.
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Dartois, E., C. Engrand, J. Duprat, M. Godard, E. Charon, L. Delauche, C. Sandt, and F. Borondics. "Dome C ultracarbonaceous Antarctic micrometeorites." Astronomy & Astrophysics 609 (January 2018): A65. http://dx.doi.org/10.1051/0004-6361/201731322.
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Context. UltraCarbonaceous Antarctic MicroMeteorites (UCAMMs) represent a small fraction of interplanetary dust particles reaching the Earth’s surface and contain large amounts of an organic component not found elsewhere. They are most probably sampling a contribution from the outer regions of the solar system to the local interplanetary dust particle (IDP) flux. Aims. We characterize UCAMMs composition focusing on the organic matter, and compare the results to the insoluble organic matter (IOM) from primitive meteorites, IDPs, and the Earth. Methods. We acquired synchrotron infrared microspectroscopy (μFTIR) and μRaman spectra of eight UCAMMs from the Concordia/CSNSM collection, as well as N/C atomic ratios determined with an electron microprobe. Results. The spectra are dominated by an organic component with a low aliphatic CH versus aromatic C=C ratio, and a higher nitrogen fraction and lower oxygen fraction compared to carbonaceous chondrites and IDPs. The UCAMMs carbonyl absorption band is in agreement with a ketone or aldehyde functional group. Some of the IR and Raman spectra show a C≡N band corresponding to a nitrile. The absorption band profile from 1400 to 1100 cm-1 is compatible with the presence of C-N bondings in the carbonaceous network, and is spectrally different from that reported in meteorite IOM. We confirm that the silicate-to-carbon content in UCAMMs is well below that reported in IDPs and meteorites. Together with the high nitrogen abundance relative to carbon building the organic matter matrix, the most likely scenario for the formation of UCAMMs occurs via physicochemical mechanisms taking place in a cold nitrogen rich environment, like the surface of icy parent bodies in the outer solar system. The composition of UCAMMs provides an additional hint of the presence of a heliocentric positive gradient in the C/Si and N/C abundance ratios in the solar system protoplanetary disc evolution.
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Arnaboldi, Magda, Claudia Pulsoni, and Ortwin Gerhard. "Elliptical galaxies/stellar halos connection." Proceedings of the International Astronomical Union 14, S353 (June 2019): 233–38. http://dx.doi.org/10.1017/s1743921319009712.
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AbstractCosmological simulations predict that early-type galaxies (ETGs) are the results of extended mass accretion histories. The latter are characterized by different numbers of mergers, mergers’ mass ratios and gas fractions, and timing. Depending on the sequence and nature of these mergers that follow the first phase of the in-situ star formation, these accretion histories may lead to ETGs that have low or high mass halos, and that rotate fast or slow. Since the stellar halos maintain the fossil records of the events that led to their formation, a discontinuity may be in place between the inner regions of ETGs and their outer halos, because the time required for the halos’ stars to exchange their energies and momenta is very long compared with the age of these systems. Exquisite deep photometry and extended spectroscopy for significant samples of ETGs are then used to quantify the occurrence and significance of such a transition in the galaxies’ structural and kinematical parameters. Once this transition radius is measured, its dependency with the effective radius of the galaxies’ light distribution and total stellar masses can be investigated. Such correlations can then be compared with the predictions of accreted, i.e. ex-situ vs. in-situ components from cosmological simulations to validate such models.
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PARK, JUN SANG, and JAE MIN HYUN. "Transient response of a compressible fluid in a rapidly rotating circular pipe." Journal of Fluid Mechanics 427 (January 25, 2001): 275–97. http://dx.doi.org/10.1017/s002211200000238x.
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The transient adjustment process of a compressible fluid in a rapidly rotating pipe is studied. The system Ekman number E is small, and the assumptions of small Mach number and the heavy-gas limit (γ = 1.0) are invoked. Fluid motion is generated by imposing a step-change perturbation in the temperature at the pipe wall Tw. Comprehensive analytical solutions are obtained by deploying the matched asymptotic technique with proper timescales O(E−1/2) and O(E−1). These analytical solutions are shown to be consistent with corresponding full numerical solutions. The detailed profiles of major variables are delineated, and evolution of velocity and temperature fields is portrayed. At moderate times, the entire flow field can be divided into two regions. In the inner inviscid region, thermo-acoustic compression takes place, and the process is isothermal–isentropic with the angular momentum being conserved. In the outer viscous region, diffusion of angular momentum occurs. The principal dynamic mechanisms are discussed, and physical rationalizations are offered. The essential differences between the responses of a compressible and an incompressible fluid are highlighted.The issue of stability of the analytically obtained flow is addressed by undertaking a formal stability analysis. It is illustrated that, within the range of parameters of present concern, the flow is stable when ε ∼ O(E).
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Kuga, Maïa, Bernard Marty, Yves Marrocchi, and Laurent Tissandier. "Synthesis of refractory organic matter in the ionized gas phase of the solar nebula." Proceedings of the National Academy of Sciences 112, no. 23 (May 26, 2015): 7129–34. http://dx.doi.org/10.1073/pnas.1502796112.
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In the nascent solar system, primitive organic matter was a major contributor of volatile elements to planetary bodies, and could have played a key role in the development of the biosphere. However, the origin of primitive organics is poorly understood. Most scenarios advocate cold synthesis in the interstellar medium or in the outer solar system. Here, we report the synthesis of solid organics under ionizing conditions in a plasma setup from gas mixtures (H2(O)−CO−N2−noble gases) reminiscent of the protosolar nebula composition. Ionization of the gas phase was achieved at temperatures up to 1,000 K. Synthesized solid compounds share chemical and structural features with chondritic organics, and noble gases trapped during the experiments reproduce the elemental and isotopic fractionations observed in primitive organics. These results strongly suggest that both the formation of chondritic refractory organics and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk, via photon- and/or electron-driven reactions and processing. Thus, synthesis of primitive organics might not have required a cold environment and could have occurred anywhere the disk is ionized, including in its warm regions. This scenario also supports N2 photodissociation as the cause of the large nitrogen isotopic range in the solar system.
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Maiolino, R. "The Metallicity Evolution of Galaxies through the Cosmic Epochs." Proceedings of the International Astronomical Union 6, S277 (December 2010): 170–73. http://dx.doi.org/10.1017/s1743921311022708.
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AbstractWe have found that local galaxies follow a very tight relation between gas metallicity, stellar mass and SFR, suggesting that their evolution is characterized by a long standing equilibrium between gas inflows, outflows and star formation. Surprisingly, even distant galaxies, out to z < 2.5, follow the same relation, suggesting that the same dominant mechanism of galaxy evolution is in place at any epoch, out to z < 2.5. However, by using deep near-IR spectroscopy (probing optical nebular lines at high-z), we find that galaxies at z > 3 deviate from such fundamental relation, by being significantly more metal poor. Spatially resolved metallicity maps of z > 3 disk galaxies reveal that they are characterized by central regions with low metallicity associated with the peak of star formation, indicating that the latter is due to massive inflow of pristine gas that both boosts star formation and dilutes the gas metallicity. Overall these results suggest that the metallicity evolution of galaxies at z > 3 is due to an excess of gas inflow at such early epochs, as expected by some recent models. Finally, we investigate the metallicity of merging systems, both locally and at high-z. By exploiting recent Herschel data, we have found that in these systems the dust content directly measured through the FIR-submm data is much higher than inferred from the metallicity measured through the optical nebular lines. The latter result suggests that, in these heavily obscured systems, optical observations only probe the outer, less enriched regions and are not representative of the bulk of the metal content.
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Chen, Hua, and Da-Lin Zhang. "On the Rapid Intensification of Hurricane Wilma (2005). Part II: Convective Bursts and the Upper-Level Warm Core." Journal of the Atmospheric Sciences 70, no. 1 (January 1, 2013): 146–62. http://dx.doi.org/10.1175/jas-d-12-062.1.
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Abstract Previous studies have focused mostly on the roles of environmental factors in the rapid intensification (RI) of tropical cyclones (TCs) because of the lack of high-resolution data in inner-core regions. In this study, the RI of TCs is examined by analyzing the relationship between an upper-level warm core, convective bursts (CBs), sea surface temperature (SST), and surface pressure falls from 72-h cloud-permitting predictions of Hurricane Wilma (2005) with the finest grid size of 1 km. Results show that both the upper-level inertial stability increases and static stability decreases sharply 2–3 h prior to RI, and that the formation of an upper-level warm core, from the subsidence of stratospheric air associated with the detrainment of CBs, coincides with the onset of RI. It is found that the development of CBs precedes RI, but most subsidence warming radiates away by gravity waves and storm-relative flows. In contrast, many fewer CBs occur during RI, but more subsidence warming contributes to the balanced upper-level cyclonic circulation in the warm-core (as intense as 20°C) region. Furthermore, considerable CB activity can still take place in the outer eyewall as the storm weakens during its eyewall replacement. A sensitivity simulation, in which SSTs are reduced by 1°C, shows pronounced reductions in the upper-level warm-core intensity and CB activity. It is concluded that significant CB activity in the inner-core regions is an important ingredient in generating the upper-level warm core that is hydrostatically more efficient for the RI of TCs, given all of the other favorable environmental conditions.
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Arekol, Lena. "Helmer Hanssens reiser i isbaksen. Med Roald Amundsen og polene som omdreiningspunkt." Nordlit, no. 32 (August 8, 2014): 117. http://dx.doi.org/10.7557/13.3076.
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<p>Helmer Hanssen published his book <em>Gjennem isbaksen. </em><em>Atten år med Roald Amundsen</em> in 1941. Five years earlier, in 1936, this book had been published in English with the title <em>Voyages of a modern Viking</em>. The Norwegian title of the book may be understood as a reflection of his polar life and almost lifelong relation to Amundsen; while the English title indicates more that Hanssen wanted to emphasis his own solid achievements in the Polar Regions. In earlier history studies Hanssen has been interpreted merely as the loyal assistant of Amundsen and as an eternal deuce. This article represents a new reading of Hanssen’s book up against previously known and unknown sources. This brings on new perspectives on the relation between Hanssen and Amundsen, but also on Hanssen himself, his relationship to his family, his perceptions of the Inuit people and his strong desire to go on a polar expedition. In this article, I argue that being the eternal deuce that is what, was Hanssen’s big chance. Amundsen gave him the possibility to experience pioneering expeditions and to see the world. My point is that Hanssen, even when living in the shadow of Amundsen, had his place in the outer circle of the spotlight.</p>
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Pilarczyk, Marcin, Bohdan Węglowski, and Lars O. Nord. "A Comprehensive Thermal and Structural Transient Analysis of a Boiler’s Steam Outlet Header by Means of a Dedicated Algorithm and FEM Simulation." Energies 13, no. 1 (December 24, 2019): 111. http://dx.doi.org/10.3390/en13010111.
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Increasing the share of renewables in energy markets influences the daily operation of thermal power units. High capacity power units are more frequently operated to balance power grids and, thus, steam boilers are exposed to unfavorable transient states. The aim of this work was to perform thermal and structural analyses of a boiler’s outlet steam header, with a capacity of 650∙103 kg/h (180 kg/s) of live steam. Based on the measured steam pressure and temperatures on the outer surface of the component, transient temperature fields were determined by means of an algorithm that allows determination of transient stress distributions on the internal and external surfaces, as well as at stress concentration regions. In parallel, a finite element method simulation was performed. A comparison of the obtained results to a finite element analysis showed satisfactory agreement. The analyses showed that the start-up time could be reduced because the total stress did not exceed the allowed values during the regular start-up of the analyzed power unit. The algorithm was efficient and easy to implement in the real control systems of the power units. The numerical approach employed in the presented algorithm also allowed for determination of the time- and place-dependent heating rate value, which can be used as input data for the control system of the power unit.
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Méndez-Abreu, Jairo, and Adriana de Lorenzo-Cáceres. "The long-lived inner bar of NGC 1291." Proceedings of the International Astronomical Union 14, S353 (June 2019): 168–71. http://dx.doi.org/10.1017/s1743921319009657.
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AbstractThe question whether stellar bars are either transitory features or long-lived structures is still matter of debate. This problem is more acute for double-barred systems where even the formation of the inner bar remains a challenge for numerical studies. We present a thorough study of the central structures of the double-barred galaxy NGC 1291. We used a two-dimensional multi-component photometric decomposition performed on the 3.6 μm images from S4 G, combined with both stellar kinematics and stellar population analysis carried out using integral field data from the MUSE TIMER project. We report on the discovery of the first Box-Peanut (B/P) structure in an inner bar detected in the face-on galaxy NGC 1291. The B/P structure is detected as bi-symmetric minima of the h4 moment of the line-of-sight velocity distribution along the major axis of the inner bar, as expected from numerical simulations. Our observations demonstrate that inner bars (similarly as outer bars) can suffer buckling instabilities, thus suggesting they can survive a long time after bar formation. The analysis of the star formation history for the structural components shaping the central regions of NGC 1291 also constrains the epoch of dynamical assembly of the inner bar, which took place >6.5 Gyr ago for NGC 1291. Our results imply that the inner bar of NGC 1291 is a long-lived structure.
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Weller, Susan J., Gerald D. Baldridge, Ulrike G. Munderloh, Hiroaki Noda, Jason Simser, and Timothy J. Kurtti. "Phylogenetic Placement of Rickettsiae from the Ticks Amblyomma americanum and Ixodes scapularis †." Journal of Clinical Microbiology 36, no. 5 (1998): 1305–17. http://dx.doi.org/10.1128/jcm.36.5.1305-1317.1998.
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A rickettsial isolate (isolate MOAa) belonging to the spotted fever group (SFG) was obtained from the lone star tick Amblyomma americanum. We used PCR to characterize the genes for the rickettsial outer membrane proteins rOmpA and rOmpB. We sequenced the PCR products (domains I of both the rompA gene and therompB gene) of MOAa and WB-8-2, another rickettsial isolate from A. americanum. To place MOAa and WB-8-2 and two other nonpathogenic isolates (Rickettsia rickettsii Hlp2 and Rickettsia montana M5/6) with respect to their putative sister species, we included them in a phylogenetic analysis of 9 Rickettsia species and 10 Rickettsia strains. Our phylogenetic results implied three evolutionary lineages of SFG rickettsiae and that WB-8-2 and MOAa were most closely related toR. montana. New World isolates were not the most closely related to each other (they did not form a clade). Rather, our results supported four independent origins (introductions) of rickettsiae into North America from different Old World regions. The results of our phylogenetic analysis did not support the hypothesis of a stable coevolution of rickettsiae and their tick hosts. Finally, we examined the rompA gene of a nonpathogenic rickettsial symbiont isolated from the tick Ixodes scapularis. In a phylogenetic analysis, the symbiont was placed as the sister toR. montana and its isolates. The relationship of this symbiont to R. montana raised questions as to the potential origin of pathogenic SFG rickettsiae from nonpathogenic tick symbionts, or vice versa.
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Kandl, K. A., J. D. Forney, and D. J. Asai. "The dynein genes of Paramecium tetraurelia: the structure and expression of the ciliary beta and cytoplasmic heavy chains." Molecular Biology of the Cell 6, no. 11 (November 1995): 1549–62. http://dx.doi.org/10.1091/mbc.6.11.1549.
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The genes encoding two Paramecium dynein heavy chains, DHC-6 and DHC-8, have been cloned and sequenced. Sequence-specific antibodies demonstrate that DHC-6 encodes ciliary outer arm beta-chain and DHC-8 encodes a cytoplasmic dynein heavy chain. Therefore, this study is the first opportunity to compare the primary structures and expression of two heavy chains representing the two functional classes of dynein expressed in the same cell. Deciliation of paramecia results in the accumulation of mRNA from DHC-6, but not DHC-8. Nuclear run-on transcription experiments demonstrate that this increase in the steady state concentration of DHC-6 mRNA is a consequence of a rapid induction of transcription in response to deciliation. This is the first demonstration that dynein, like other axonemal components, is transcriptionally regulated during reciliation. Analyses of the sequences of the two Paramecium dyneins and the dynein heavy chains from other organisms indicate that the heavy chain can be divided into three regions: 1) the sequence of the central catalytic domain is conserved among all dyneins; 2) the tail domain sequence, consisting of the N-terminal 1200 residues, differentiates between axonemal and cytoplasmic dyneins; and 3) the N-terminal 200 residues are the most divergent and appear to classify the isoforms. The organization of the heavy chain predicts that the variable tail domain may be sufficient to target the dynein to the appropriate place in the cell.
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Seddighi Takrami, Masumeh, Alireza Ganji, Arash Gorabjiripor, Mohammadreza Ansari, and Afshin Ashjaardalan. "Investigation of mineralization in copper-porphyry molybdenum using hydrothermal alternation in northwest region of Iran." Nexo Revista Científica 33, no. 02 (December 31, 2020): 746–52. http://dx.doi.org/10.5377/nexo.v33i02.10806.
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Identification and determination of areas with mineral potential is one of the major and important applications of remote sensing in the field of mineral exploration. The aim of the present study was Identification of hydrothermal ultrason region using Landsat multispectral satellite imagery and hyperion hyperspectral imagery. To conduct this research, first the Advanced Space Borne thermal reflection radiometric data and the base metal mapping of the harvest were examined. Using principal component analysis using the key spectral change properties of key minerals, PC 2 enhanced the altered regions. Then we studied the MF spectral library and laboratory spectra of samples in the study area. In this study, two different methods, principal component analysis (PCA) and matched filter processing (MF), were compared and combined for mapping. In both methods, the key properties of changing the range of minerals in the study area were used. The results of the present study showed that from the top of the deposit to the bottom, the type of mineralization is gradually increasing. Chalcopyrite spraying gradually decreases from the depth of the deposit to the outer regions and vice versa, the amount of pyrite spraying increases. In Sungun, the main mineralization of copper in the second (main) stage of the activity of mineralized solutions has taken place, during which chalcopyrite has been extensively left in the form of vessels and sprays in rocks. Molybdenite is formed in a wide range of second stage mineralization processes in several successive phases. In the early processes, this mineral is sprayed and less in the form of veins and in later stages more in the form of veins. Thus, the copper-molybdenum porphyry deposit of Sungun Ahar, with a very high reserve of 7.1 billion tons and an average copper grade of 0.75 ٪ And molybdenite by-mineral in the early 80's will certainly be exploited among the largest copper mines in Iran.
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BERGMANN, R., L. TOPHØJ, T. A. M. HOMAN, P. HERSEN, A. ANDERSEN, and T. BOHR. "Polygon formation and surface flow on a rotating fluid surface." Journal of Fluid Mechanics 679 (May 24, 2011): 415–31. http://dx.doi.org/10.1017/jfm.2011.152.
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We present a study of polygons forming on the free surface of a water flow confined to a stationary cylinder and driven by a rotating bottom plate as described by Jansson et al. (Phys. Rev. Lett., vol. 96, 2006, 174502). In particular, we study the case of a triangular structure, either completely ‘wet’ or with a ‘dry’ centre. For the dry structures, we present measurements of the surface shapes and the process of formation. We show experimental evidence that the formation can take place as a two-stage process: first the system approaches an almost stable rotationally symmetric state and from there the symmetry breaking proceeds like a low-dimensional linear instability. We show that the circular state and the unstable manifold connecting it with the polygon solution are universal in the sense that very different initial conditions lead to the same circular state and unstable manifold. For a wet triangle, we measure the surface flows by particle image velocimetry (PIV) and show that there are three vortices present, but that the strength of these vortices is far too weak to account for the rotation velocity of the polygon. We show that partial blocking of the surface flow destroys the polygons and re-establishes the rotational symmetry. For the rotationally symmetric state our theoretical analysis of the surface flow shows that it consists of two distinct regions: an inner, rigidly rotating centre and an outer annulus, where the surface flow is that of a point vortex with a weak secondary flow. This prediction is consistent with the experimentally determined surface flow.
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Makrariya, Akshara, and Neeru Adlakha. "Quantitative Study of Thermal Disturbances Due to Nonuniformly Perfused Tumors in Peripheral Regions of Women’s Breast." Cancer Informatics 16 (January 1, 2017): 117693511770089. http://dx.doi.org/10.1177/1176935117700894.
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Background: Mathematical modeling of biothermal processes is widely used to enhance the quantitative understanding of thermoregulation system of human body organs. This quantitative knowledge of thermal information of various human body organs can be used for developing clinical applications. In the past, investigators have studied thermal distribution in hemisphere-shaped human breast in the presence of sphere-shaped tumor. The shape and size of the breast as well as tumor may also affect thermal distribution which can have serious implications in thermography. In this article, a model of thermal disturbances in peripheral regions of ellipsoid-shaped human breast involving ellipse-shaped nonuniformly perfused tumor has been developed for a 2-dimensional steady-state case. The modeling study will provide biomedical scientists vital insights of thermal changes occurring due to the shape and size of breast and tumor which can influence the development of protocols of thermography for diagnosis of tumors in women’s breast. Method: We have incorporated the significant parameters such as blood flow, metabolic activity, and thermal conductivity in the thermal model for normal and malignant tissues. The controlled metabolic activity has been incorporated for normal tissues, and uncontrolled metabolic activity has been incorporated for tumor regions. The peripheral regions of breast are divided into 3 major layers, namely, epidermis, dermis, and subdermal tissues. An ellipse-shaped nonuniformly perfused tumor is assumed to be present in dermal layers. The nonuniformly perfused tumor is divided into 2 natural components, namely, the necrotic core and tumor periphery. The outer surface of the breast is assumed to be exposed to the environment, and the heat loss takes place by conduction, convection, radiation, and evaporation. The finite element approach is used to obtain the solution. The numerical results have been used to study the effect of shape and size of tumor on temperature distribution in matured breast of different shapes. Results: By selecting appropriate model parameters, we have shown the spatial thermal variation in matured breast of different shapes which could be replicated by the proposed model. We have also shown the thermal disturbances caused by different shapes and sizes of tumors by selecting appropriate values of parameters. In addition, the thermal information from our model provides us the basis for prediction of shape and size of tumors in terms of change of the slope of temperature profiles at the junction of tumor and normal tissues and tumor periphery and tumor core. Conclusions: The proposed model was successfully used to study the impact of different sizes and shapes of nonuniformly perfused tumor on thermograms in peripheral regions of ellipse-shaped woman’s breast. The proposed model is more realistic in terms of shape and size of tumors and woman’s breast in comparison with earlier models reported in the literature. The finite element discretization of breast into large number of triangular ring elements effectively models the heterogeneity of region. The changes in slope of the thermal curves at the junctions of various peripheral and tumor layers are due to the nonhomogeneous nature of the region. The location of major thermal disturbances in the tissues indicates the presence of tumor. The change in the slope of the thermal curves gives us idea about the position, type, and size of the tumors in the peripheral tissues. This thermal information can be exploited for detection of tumors by thermographic techniques.
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Hofmann, Richard, Michael Hautmann, and Hugo Bucher. "A new paleoecological look at the Dinwoody Formation (Lower Triassic, western USA): intrinsic versus extrinsic controls on ecosystem recovery after the end-Permian mass extinction." Journal of Paleontology 87, no. 5 (September 2013): 854–80. http://dx.doi.org/10.1666/12-153.
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The Dinwoody Formation of the western United States represents an important archive of Early Triassic ecosystems in the immediate aftermath of the end-Permian mass extinction. We present a systematic description and a quantitative paleoecological analysis of its benthic faunas in order to reconstruct benthic associations and to explore the temporal and spatial variations of diversity, ecological structure and taxonomic composition throughout the earliest Triassic of the western United States. A total of 15 bivalve species, two gastropod species, and two brachiopod species are recognized in the study area. The paleoecological analysis shows that the oldest Dinwoody communities are characterized by low diversity, low ecological complexity and high dominance of few species. We suggest that this low diversity most likely reflects the consequences of the mass extinction in the first place and not necessarily the persistence of environmental stress. Whereas this diversity pattern persists into younger strata of the Dinwoody Formation in outer shelf environments, an increase in richness, evenness and guild diversity occurred around the Griesbachian–Dienerian boundary in more shallow marine habitats. This incipient recovery towards the end of the Griesbachian is in accordance with observations from other regions and thus probably represents an interregional signal. In contrast to increasing richness within communities (alpha-diversity), beta-diversity remained low during the Griesbachian and Dienerian in the study area. This low beta-diversity reflects a wide environmental and geographical range of taxa during the earliest Triassic, indicating that the increase of within-habitat diversity has not yet led to significant competitive exclusion. We hypothesize that the well-known prevalence of generalized taxa in post-extinction faunas is primarily an effect of reduced competition that allows species to exist through the full range of their fundamental niches, rather than being caused by unusual and uniform environmental stress.
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Khayeat, Ali Retha Hasoon, Ashwan A. Abdulmunem, Rafeef Fauzi Najim Al-Shammari, and Xianfang Sun. "Traffic Sign Detection and Classification based on Combination of MSER Features and Multi-language OCR." Webology 17, no. 2 (December 21, 2020): 394–403. http://dx.doi.org/10.14704/web/v17i2/web17040.
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Road signs are so important because they help preserve safe driving conditions; they also influence the safety of drivers and pedestrians. Without these signs, no one would know the driving speed limit, on which direction to drive down a road, any upcoming hazard, or whether they are approaching a merge. It would be chaotic to drive in such situations. Moreover, these signs help new drivers to find their way in the absence of navigators. Therefore, traffic sign recognition takes a critical place in computer vision applications to develop an effective algorithm. In order to tackle this challenge, we proposed the use of Multi-language Traffic Sign Detection and Classification. One of our contributions in this work is that, instead of using the standard grayscale image, we used the RGB colored image. This image is converted into the 2D highest-level grayscale image using the largest values of each pixel in the RGB channels. The novel generated image has the strongest features of the RGB image that make the features distinct and more informative in the classification step. Consider that, in general, the traffic sign has two colors only, the foreground (text location) and background (non-text location). The Maximally Stable Extremal Regions (MSER) used to extract features from the 2D image where the locations of interest are well-identified exclusively by an extremal property of the intensity function in the location and on its outer boundary. The geometrical properties and thinning operations were used to remove the non-text locations. A multi-language OCR was used to understand multi-language. This proposed method has been tested using 240 images which were collected from the Internet and two datasets. The experimental results demonstrated the performance of the proposed method where the traffic sign detected in 92% of the tested images with a very high percentage of localization.
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Flores, Anthony M., Adam B. Mantz, Steven W. Allen, R. Glenn Morris, Rebecca E. A. Canning, Lindsey E. Bleem, Michael S. Calzadilla, Benjamin T. Floyd, Michael McDonald, and Florian Ruppin. "The history of metal enrichment traced by X-ray observations of high-redshift galaxy clusters." Monthly Notices of the Royal Astronomical Society 507, no. 4 (August 30, 2021): 5195–204. http://dx.doi.org/10.1093/mnras/stab2430.
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ABSTRACT We present the analysis of deep X-ray observations of 10 massive galaxy clusters at redshifts 1.05 < z < 1.71, with the primary goal of measuring the metallicity of the intracluster medium (ICM) at intermediate radii, to better constrain models of the metal enrichment of the intergalactic medium. The targets were selected from X-ray and Sunyaev–Zel’dovich effect surveys, and observed with both the XMM–Newton and Chandra satellites. For each cluster, a precise gas mass profile was extracted, from which the value of r500 could be estimated. This allows us to define consistent radial ranges over which the metallicity measurements can be compared. In general, the data are of sufficient quality to extract meaningful metallicity measurements in two radial bins, r < 0.3r500 and 0.3 < r/r500 < 1.0. For the outer bin, the combined measurement for all 10 clusters, Z/Z⊙ = 0.21 ± 0.09, represents a substantial improvement in precision over previous results. This measurement is consistent with, but slightly lower than, the average metallicity of 0.315 solar measured at intermediate-to-large radii in low-redshift clusters. Combining our new high-redshift data with the previous low-redshift results allows us to place the tightest constraints to date on models of the evolution of cluster metallicity at intermediate radii. Adopting a power-law model of the form Z ∝ (1 + z)γ, we measure a slope $\gamma = -0.5^{+0.4}_{-0.3}$, consistent with the majority of the enrichment of the ICM having occurred at very early times and before massive clusters formed, but leaving open the possibility that some additional enrichment in these regions may have occurred since a redshift of 2.
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Filippidis, Christos. "Between Ferality and Resilience: Global (South) Urbanization as a Counterinsurgency Research Object." Human Geography 11, no. 3 (November 2018): 30–42. http://dx.doi.org/10.1177/194277861801100303.
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Today, urbanization is described as one of the major global challenges. The rapid demographic transformations taking place in certain regions of the Global South — especially in countries of Africa and Southeast Asia — bring a sense of urgency to the discussion on cities. Rapid and uncontrolled urbanization in Global South, combined with social inequalities, poverty and environmental degradation, renders many urban populations vulnerable and precarious. With an emphasis on the urban expansion of the Global South, an international agenda is formed nowadays, focusing on the structural functions of the cities and their shielding against the negative effects of the current global crisis; a crisis taking today the form of an economic, environmental, and migration crisis. Thus, sustainability and resilience of the cities, and especially of those in the Global South, are turned into the key questions of urban planning and urban governance policies. Yet, they are also gradually turned into an object of military problematizations, as Western armed forces are strongly interested today in the urban phenomena and the functions of the cities, perceiving urban environment not only as a potential field of military operations but as a source of irregular threats; describing, in other words, the cities of the Global South not only as sites that host potential enemies but as enemies per se. More specifically, from the end of the 20th century U.S. military focuses on urban informality and its security implications, imposing a new understanding of the urban world. This is today more evident, as rapid demographic changes render urban systems and informal urban settlements in particular more vulnerable, and this vulnerability is directly problematized in public security terms. Through the relevant anti-urban theoretical frameworks, the cities of the Global South are conceived as feral systems that have to be tamed; and this taming calls for direct intervention. Military imposes, in this way, its presence in the field of urban problematizations, and building on the deception of contemporary neoliberal narratives calls today for urban resilience. As the world urbanizes rapidly and the notions of crisis and emergency are shaping the dominant social imaginary and the modern governmental agenda, urban sustainability, adaptability, and resilience are turned into an overall public security issue and eventually into an object of military interest. Hence, when the military theorists wonder how to make contemporary “fragile” urban systems more “resilient”, they actually wonder how to build forcibly resilient subjectivities and impose, after all, resilience and patience against an inescapable oppression.
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Solé, Mónica, Carlos Bantar, Karl Indest, Yan Gu, Ramesh Ramamoorthy, Richard Coughlin, and Mario T. Philipp. "Borrelia burgdorferi Escape Mutants That Survive in the Presence of Antiserum to the OspA Vaccine Are Killed When Complement Is Also Present." Infection and Immunity 66, no. 6 (June 1, 1998): 2540–46. http://dx.doi.org/10.1128/iai.66.6.2540-2546.1998.
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ABSTRACT As an initial attempt to investigate the possible role of outer surface protein A (OspA) escape mutants of Borrelia burgdorferi in decreasing the efficacy of the OspA vaccine, mutants of the HB19 strain of B. burgdorferi sensu stricto were selected in vitro from an uncloned, low-passage-number isolate. The antiserum used for selection was obtained from rhesus monkeys that had been given a vaccine of the same formulation and dose, and by the same route of administration, as that given to humans in several trials. All of the mutants selected in liquid medium and subsequently cloned twice in solid medium expressed a single abundant protein of 28 to 34 kDa instead of both OspA and OspB. Depending on the mutant, this protein reacted strongly, weakly, or not detectably with the anti-OspA antibody used for selection. Analysis of the ospAB locus of each of four representatives from these three groups of mutants by PCR with oligonucleotide primers that hybridize to flanking regions of theospAB operon, and of the corresponding phenotype with monoclonal antibodies that bind to the amino or carboxyl terminus of the OspA or OspB polypeptide, indicated that in all cases a deletion within the operon had occurred. Spirochetes from the four mutant strains chosen for further analysis could be killed in antibody-dependent, complement-mediated killing assays with the selecting anti-OspA antibody, despite their resistance to killing with this antibody in the absence of complement. Complement-mediated killing occurred at an antibody concentration higher than that required to kill wild-type spirochetes. If anti-OspA antibody acts only within the tick, where complement is probably ineffective due to tick-derived decomplementing factors, then OspA escape mutants, if infectious, could seriously diminish the efficacy of OspA vaccines. On the other hand, if the killing of B. burgdorferi with anti-OspA antibody also takes place within the human host, then our results indicate that chimeric/deletion escape mutants will be killed as well.
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Jin, S., H. Dannerbauer, B. Emonts, P. Serra, C. D. P. Lagos, A. P. Thomson, L. Bassini, et al. "COALAS." Astronomy & Astrophysics 652 (August 2021): A11. http://dx.doi.org/10.1051/0004-6361/202040232.
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We report a detailed CO(1−0) survey of a galaxy protocluster field at z = 2.16, based on 475 h of observations with the Australia Telescope Compact Array. We constructed a large mosaic of 13 individual pointings, covering an area of 21 arcmin2 and ±6500 km s−1 range in velocity. We obtained a robust sample of 46 CO(1−0) detections spanning z = 2.09 − 2.22, constituting the largest sample of molecular gas measurements in protoclusters to date. The CO emitters show an overdensity at z = 2.12 − 2.21, suggesting a galaxy super-protocluster or a protocluster connected to large-scale filaments of ∼120 cMpc in size. We find that 90% of CO emitters have distances >0.′5−4′ to the center galaxy, indicating that small area surveys would miss the majority of gas reservoirs in similar structures. Half of the CO emitters have velocities larger than escape velocities, which appears gravitationally unbound to the cluster core. These unbound sources are barely found within the R200 radius around the center, which is consistent with a picture in which the cluster core is collapsed while outer regions are still in formation. Compared to other protoclusters, this structure contains a relatively higher number of CO emitters with relatively narrow line widths and high luminosities, indicating galaxy mergers. We used these CO emitters to place the first constraint on the CO luminosity function and molecular gas density in an overdense environment. The amplitude of the CO luminosity function is 1.6 ± 0.5 orders of magnitude higher than that observed for field galaxy samples at z ∼ 2, and one order of magnitude higher than predictions for galaxy protoclusters from semi-analytical SHARK models. We derive a high molecular gas density of 0.6 − 1.3 × 109 M⊙ cMpc−3 for this structure, which is consistent with predictions for cold gas density of massive structures from hydro-dynamical DIANOGA simulations.
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Venuti, L., L. Prisinzano, G. G. Sacco, E. Flaccomio, R. Bonito, F. Damiani, G. Micela, et al. "The Gaia-ESO Survey and CSI 2264: Substructures, disks, and sequential star formation in the young open cluster NGC 2264." Astronomy & Astrophysics 609 (December 22, 2017): A10. http://dx.doi.org/10.1051/0004-6361/201731103.
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Context. Reconstructing the structure and history of young clusters is pivotal to understanding the mechanisms and timescales of early stellar evolution and planet formation. Recent studies suggest that star clusters often exhibit a hierarchical structure, possibly resulting from several star formation episodes occurring sequentially rather than a monolithic cloud collapse. Aims. We aim to explore the structure of the open cluster and star-forming region NGC 2264 (~3 Myr), which is one of the youngest, richest and most accessible star clusters in the local spiral arm of our Galaxy; we link the spatial distribution of cluster members to other stellar properties such as age and evolutionary stage to probe the star formation history within the region. Methods. We combined spectroscopic data obtained as part of the Gaia-ESO Survey (GES) with multi-wavelength photometric data from the Coordinated Synoptic Investigation of NGC 2264 (CSI 2264) campaign. We examined a sample of 655 cluster members, with masses between 0.2 and 1.8 M⊙ and including both disk-bearing and disk-free young stars. We used Teff estimates from GES and g,r,i photometry from CSI 2264 to derive individual extinction and stellar parameters. Results. We find a significant age spread of 4–5 Myr among cluster members. Disk-bearing objects are statistically associated with younger isochronal ages than disk-free sources. The cluster has a hierarchical structure, with two main blocks along its latitudinal extension. The northern half develops around the O-type binary star S Mon; the southern half, close to the tip of the Cone Nebula, contains the most embedded regions of NGC 2264, populated mainly by objects with disks and ongoing accretion. The median ages of objects at different locations within the cluster, and the spatial distribution of disked and non-disked sources, suggest that star formation began in the north of the cluster, over 5 Myr ago, and was ignited in its southern region a few Myr later. Star formation is likely still ongoing in the most embedded regions of the cluster, while the outer regions host a widespread population of more evolved objects; these may be the result of an earlier star formation episode followed by outward migration on timescales of a few Myr. We find a detectable lag between the typical age of disk-bearing objects and that of accreting objects in the inner regions of NGC 2264: the first tend to be older than the second, but younger than disk-free sources at similar locations within the cluster. This supports earlier findings that the characteristic timescales of disk accretion are shorter than those of disk dispersal, and smaller than the average age of NGC 2264 (i.e., ≲3 Myr). At the same time, we note that disks in the north of the cluster tend to be shorter-lived (~2.5 Myr) than elsewhere; this may reflect the impact of massive stars within the region (notably S Mon), that trigger rapid disk dispersal. Conclusions. Our results, consistent with earlier studies on NGC 2264 and other young clusters, support the idea of a star formation process that takes place sequentially over a prolonged span in a given region. A complete understanding of the dynamics of formation and evolution of star clusters requires accurate astrometric and kinematic characterization of its population; significant advance in this field is foreseen in the upcoming years thanks to the ongoing Gaia mission, coupled with extensive ground-based surveys like GES.
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Lundin, R., M. Yamauchi, J. A. Sauvaud, and A. Balogh. "Magnetospheric plasma boundaries: a test of the frozen-in magnetic field theorem." Annales Geophysicae 23, no. 7 (October 14, 2005): 2565–78. http://dx.doi.org/10.5194/angeo-23-2565-2005.
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Abstract. The notion of frozen-in magnetic field originates from H. Alfvén, the result of a work on electromagnetic-hydrodynamic waves published in 1942. After that, the notion of frozen-in magnetic field, or ideal MHD, has become widely used in space plasma physics. The controversy on the applicability of ideal MHD started in the late 1950s and has continued ever since. The applicability of ideal MHD is particularly interesting in regions where solar wind plasma may cross the magnetopause and access the magnetosphere. It is generally assumed that a macroscopic system can be described by ideal MHD provided that the violations of ideal MHD are sufficiently small-sized near magnetic x-points (magnetic reconnection). On the other hand, localized departure from ideal MHD also enables other processes to take place, such that plasma may cross the separatrix and access neighbouring magnetic flux tubes. It is therefore important to be able to quantify from direct measurements ideal MHD, a task that has turned out to be a major challenge. An obvious test is to compare the perpendicular electric field with the plasma drift, i.e. to test if E=–v×B. Yet another aspect is to rule out the existence of parallel (to B) electric fields. These two tests have been subject to extensive research for decades. However, the ultimate test of the "frozen-in" condition, based on measurement data, is yet to be identified. We combine Cluster CIS-data and FGM-data, estimating the change in magnetic flux (δB/δt) and the curl of plasma –v×B(∇×(v×B)), the terms in the "frozen-in equation". Our test suggests that ideal MHD applies in a macroscopic sense in major parts of the outer magnetosphere, for instance, in the external cusp and in the high-latitude magnetosheath. However, we also find significant departures from ideal MHD, as expected on smaller scales, but also on larger scales, near the cusp and in the magnetosphere-boundary layer. We discuss the importance of these findings. Keywords. Magnetospheric physics (Magnetopause, cusp and boundary layers; Solar wind-magnetosphere interactions) – Space plasma physics
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Park, J. H., J. Juzwik, and L. M. Haugen. "Ceratocystis Canker of Bitternut Hickory Caused by Ceratocystis smalleyi in the North-Central and Northeastern United States." Plant Disease 94, no. 2 (February 2010): 277. http://dx.doi.org/10.1094/pdis-94-2-0277b.
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Between 2006 and 2008, diffuse cankers without surrounding callus and callus-edged sunken cankers were observed on main stems of poletimber (13 to 28 cm in diameter at 1.4 m high) and sawtimber (>28 cm in diameter) bitternut hickory (Carya cordiformis) in Iowa, Indiana, Minnesota, New York, Ohio, and Wisconsin. Reddish, inner bark necrosis and reddish brown sapwood discoloration were associated with the cankers. Entry or exit holes of the hickory bark beetle (Scolytus quadrispinosus) were commonly associated with the cankers. Ceratocystis smalleyi was consistently isolated from the margins of cankers or discolored sapwood of assayed samples. When cultured on 2% malt yeast extract agar (MYEA), the isolates produced perithecia, ascospores, endoconidiophores, and conidia diagnostic of C. smalleyi (1). To confirm identification, the translation elongation factor (tef) 1-α gene and the internally transcribed spacer (ITS) regions were sequenced. DNA for both regions was extracted from mycelia growing on MYEA. The tef sequences (GenBank Accession Nos. GU201529–201539) and the ITS sequences (GenBank Accession Nos. GU190734–190745) were 98 to 100% similar to sequences of C. smalleyi isolates (GenBank Accession Nos. EF070408 and AY9907030–907032). Pathogenicity tests were conducted with local isolates (two per site) on healthy Carya cordiformis (13 to 28 cm in diameter) in forest stands in three states. In May 2007, one fungus-colonized MYEA disk or sterile MYEA agar was placed in one of two holes (0.6 cm in diameter) drilled to the cambium on stems of 10 trees in Allamakee County, IA. Sterile moist cotton and laboratory film held the disks in place. After 12 months, diffuse cankers were found for all but one fungus inoculation site; no cankers occurred with control inoculations. Reddish brown, inner bark necrosis (mean area 22.4 cm2) and sapwood discoloration (mean volume 38.1 cm3) were associated with the cankers. C. smalleyi was recovered from five of nine cankers, but not from the control wounds. In June 2008, 0.1 ml of spore suspension (1 × 104 ascospores/ml) of C. smalleyi or sterile dH20 was pipetted into four drilled holes (to the outer sapwood) of four trees in Chippewa County, WI. Holes were sealed with moist cotton and masking tape. Two months later, diffuse cankers with reddish inner bark (mean 49.7 cm2) surrounded 16 inoculation points; no cankers or inner bark necrosis was observed for the control points. In a similar trial, a spore suspension or sterile water was placed into four drilled holes covered with moist cotton and moldable putty on six trees in Olmstead County, MN. Fourteen months later, either diffuse or sunken cankers with reddish, inner bark necrosis (mean 22.3 cm2) were observed surrounding all inoculated points while all control points were callus closed. For the latter two trials, long, narrow discoloration (reddish brown) was found in the sapwood associated with each canker; no sapwood discoloration was observed for the control points. In addition, C. smalleyi was reisolated from all cankered stems in Wisconsin and from 21 of 24 cankers in Minnesota, but not from the controls. This report verifies the ability of C. smalleyi to cause a newly described canker disease on poletimber-sized hickories. We hypothesize that this disease is contributing to the death of hickory bark beetle-attacked Carya cordiformis in the eastern United States. Reference: (1) J. Johnson et al. Mycologia 97:1067, 2005.