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Perris, R., D. Krotoski, T. Lallier, C. Domingo, J. M. Sorrell, and M. Bronner-Fraser. "Spatial and temporal changes in the distribution of proteoglycans during avian neural crest development." Development 111, no. 2 (1991): 583–99. http://dx.doi.org/10.1242/dev.111.2.583.
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In this study, we describe the distribution of various classes of proteoglycans and their potential matrix ligand, hyaluronan, during neural crest development in the trunk region of the chicken embryo. Different types of chondroitin and keratan sulfate proteoglycans were recognized using a panel of monoclonal antibodies produced against specific epitopes on their glycosaminoglycan chains. A heparan sulfate proteoglycan was identified by an antibody against its core protein. The distribution of hyaluronan was mapped using a biotinylated fragment that corresponds to the hyaluronan-binding region of cartilage proteoglycans. Four major patterns of proteoglycan immunoreactivity were observed. (1) Chondroitin-6-sulfate-rich proteoglycans and certain keratin sulfate proteoglycans were absent from regions containing migrating neural crest cells, but were present in interstitial matrices and basement membranes along prospective migratory pathways such as the ventral portion of the sclerotome. Although initially distributed uniformly along the rostrocaudal extent of the sclerotome, these proteoglycans became rearranged to the caudal portion of the sclerotome with progressive migration of neural crest cells through the rostral sclerotome and their aggregation into peripheral ganglia. (2) A subset of chondroitin/keratan sulfate proteoglycans bearing primarily unsulfated chondroitin chains was observed exclusively in regions where neural crest cells were absent or delayed from entering, such as the perinotochordal and subepidermal spaces. (3) A subset of chondroitin/keratan sulfate proteoglycans was restricted to the perinotochordal region and, following gangliogenesis, was arranged in a metameric pattern corresponding to the sites where presumptive vertebral arches form. (4) Certain keratan sulfate proteoglycans and a heparan sulfate proteoglycan were observed in basement membranes and in an interstitial matrix uniformly distributed along the rostrocaudal extent of the sclerotome. After gangliogenesis, the neural crest-derived dorsal root and sympathetic ganglia contained both these proteoglycan types, but were essentially free of other chondroitin/keratan-proteoglycan subsets. Hyaluronan generally colocalized with the first set of proteoglycans, but also was concentrated around migrating neural crest cells and was reduced in neural crest-derived ganglia. These observations demonstrate that proteoglycans have diverse and dynamic distributions during times of neural crest development and chondrogenesis of the presumptive vertebrae. In general, chondroitin/keratan sulfate proteoglycans are abundant in regions where neural crest cells are absent, and their segmental distribution inversely correlates with that of neural crest-derived ganglia.
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Zhang, Yangyang, Qingfu Huang, Shizhuang Chen, Fudong Chi, Huachen Wang, and Weiya Xu. "Spatial and Temporal Distribution Characteristics of Landslide Surge Based on Large-Scale Physical Modeling Experiment." Applied Sciences 14, no. 5 (2024): 2104. http://dx.doi.org/10.3390/app14052104.
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Surge is a common secondary disaster caused by reservoir landslides. The study of its spatial and temporal distribution characteristics is important since it affects not only the normal operation of reservoirs but also the safety of people residing along the river. This paper presents a large-scale three-dimensional physical modeling experiment using a near-dam high-position landslide project as a prototype. It investigated the relationships between the river course characteristics, the landslide volume, the head wave velocity of the landslide surge, the waveform of surges, and the head wave crest of the wave along the course in depth. The results indicate that the head wave velocity of the landslide surge is basically unchanged during the propagation process, and it is minimally affected by the landslide volume. The waveform distribution characteristics and head wave crests change considerably in the diversion area and the curved areas but remain mostly unchanged in the topographic similarity area. In addition, there is a negative correlation between the head wave crest and the cross-sectional area of the river course. Furthermore, under conditions of a large landslide volume, the influence of the cross-sectional area of the river channel on the wave height of landslide surges becomes more significant. Finally, the maximum wave height along the course may not necessarily occur in the head wave crest; it could occur in the second wave or even the subsequent ones.
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Taneyhill, Lisa A., and Marianne Bronner-Fraser. "Dynamic Alterations in Gene Expression after Wnt-mediated Induction of Avian Neural Crest." Molecular Biology of the Cell 16, no. 11 (2005): 5283–93. http://dx.doi.org/10.1091/mbc.e05-03-0210.
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The Wnt signaling pathway is important in the formation of neural crest cells in many vertebrates, but the downstream targets of neural crest induction by Wnt are largely unknown. Here, we examined quantitative changes in gene expression regulated by Wnt-mediated neural crest induction using quantitative PCR (QPCR). Induction was recapitulated in vitro by adding soluble Wnt to intermediate neural plate tissue cultured in collagen, and induced versus control tissue were assayed using gene-specific primers at times corresponding to premigratory (18 and 24 h) or early (36 h) stages of crest migration. The results show that Wnt signaling up-regulates in a distinct temporal pattern the expression of several genes normally expressed in the dorsal neural tube (slug, Pax3, Msx1, FoxD3, cadherin 6B) at “premigratory” stages. While slug is maintained in early migrating crest cells, Pax3, FoxD3, Msx1 and cadherin 6B all are down-regulated by the start of migration. These results differ from the temporal profile of these genes in response to the addition of recombinant BMP4, where gene expression seems to be maintained. Interestingly, expression of rhoB is unchanged or even decreased in response to Wnt-mediated induction at all times examined, though it is up-regulated by BMP signals. The temporal QPCR profiles in our culture paradigm approximate in vivo expression patterns of these genes before neural crest migration, and are consistent with Wnt being an initial neural crest inducer with additional signals like BMP and other factors maintaining expression of these genes in vivo. Our results are the first to quantitatively describe changes in gene expression in response to a Wnt or BMP signal during transformation of a neural tube cell into a migratory neural crest cell.
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Duband, J. L., and J. P. Thiery. "Spatial and temporal distribution of vinculin and talin in migrating avian neural crest cells and their derivatives." Development 108, no. 3 (1990): 421–33. http://dx.doi.org/10.1242/dev.108.3.421.
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Neural crest cells express different adhesion modes at each phase of their development starting with their separation from the neural tube, followed by migration along definite pathways throughout the embryo, and finally to settlement and differentiation in elected embryonic regions. In order to determine possible changes in the cytoskeleton organization and function during these processes, we have studied the in situ distribution of two major cytoskeleton-associated elements involved in the membrane anchorage of actin microfilaments, i.e. vinculin and talin, during the ontogeny of the neural crest and its derivatives in the avian embryo. Prior to emigration, neural crest cells exhibited both vinculin and talin at levels similar to the neighbouring neural epithelial cells, and this expression apparently did not change as cells became endowed with migratory properties. However, vinculin became selectively enhanced in neural crest cells as they further migrated towards their final destination. This increase in vinculin amount was particularly striking in vagal and truncal neural crest cells entering cellular environments, such as the sclerotome and the gut mesenchyme. Talin was also expressed by neural crest cells but, in contrast to vinculin, staining was not conspicuous compared to neighbouring mesenchymal cells. High levels of vinculin persisted throughout embryogenesis in almost all neural derivatives of the neural crest, including the autonomous and sensory ganglia and Schwann cells along the peripheral nerves. In contrast, the non-neural derivatives of the neural crest rapidly lost their prominent vinculin staining after migration. The pattern of talin in the progeny of the neural crest was complex and varied with the cell types: for example, some cranial sensory ganglia expressed high amounts of the molecule whereas autonomic ganglia were nearly devoid of it. Our results suggest that (i) vinculin and talin may follow independent regulatory patterns within the same cell population, (ii) the level of expression of vinculin and talin in neural crest cells may be consistent with the rapid, constant modulations of their adhesive properties, and (iii) the expression patterns of the two molecules may also be correlated with the genesis of the peripheral nervous system.
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Lee, Yoon Ho, Sin Chul Lee, and Kun Hwang. "Anchoring Temporalis Muscle to Porous Polyethylene Sheet Fixed at the Temporal Crest in the Temporal Depression." Journal of Craniofacial Surgery 23, no. 1 (2012): e48-e50. http://dx.doi.org/10.1097/scs.0b013e318241e1ba.
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Montgomery, J., D. Bodznick, and M. Halstead. "Hindbrain signal processing in the lateral line system of the dwarf scorpionfish Scopeana papillosus." Journal of Experimental Biology 199, no. 4 (1996): 893–99. http://dx.doi.org/10.1242/jeb.199.4.893.
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Recordings were made from primary afferent fibres and secondary projection neurones (crest cells) in the mechanosensory lateral line system of the dwarf scorpionfish. Crest cells were identified by antidromic stimulation from the contralateral midbrain. Differences between primary afferent fibre and crest cell response characteristics are indicative of signal processing by the neuronal circuitry of the medial octavolateralis nucleus. There are a number of differences between primary afferent fibres and crest cells. Primary afferents have relatively high levels of spontaneous activity (mean close to 40 impulses s-1) and many of them are strongly modulated by ventilation. By contrast, crest cells have a much lower rate of spontaneous activity that is not obviously modulated by ventilation. Primary afferents show a simple tonic response to a maintained stimulus, whereas crest cells show a variety of temporal response properties, but in general show a phasic/tonic response to the same prolonged stimulus. Afferents are most sensitive to frequencies of stimulation around 100 Hz; in contrast, crest cells show a strong suppression of activity at this frequency. Crest cells are most responsive around 50 Hz. These afferent/secondary comparisons show similarities with those reported for allied electrosensory and auditory pathways.
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Kot, T. F., I. M. Lutsiuk, and O. V. Synytskyi. "The structural features of the sculls of animals of a series of Carnivore." Scientific Messenger of LNU of Veterinary Medicine and Biotechnology 21, no. 93 (2019): 65–69. http://dx.doi.org/10.32718/nvlvet9312.
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Predators is medium-sized and large mammal leading a terrestrial way of life. They are mostly carnivorous animals, the nature of nutrition of which indicate certain devices are reflected in the structure of the scull. The aim of the work is to conduct a comparative anatomical study of the structure of the scull and to determine the craniometric indicators in animals of families Feline (Domestic cat), Canine (Domestic dog, Wolf, Fox ordinary) and Mustelidae (stone marten, forest polecat, badger ordinary) a squad of Carnivore. Comparative anatomical, craniological and statistical methods of research were used. It was found that the scull of test animals is of a General anatomical structure (wide temporal fossa, a deep masseteric fossa, well-defined nuchal and external sagittal crests, the presence of angular process on mandible, relatively large tympanic bullas, underdeveloped lacrimal bone) and species differences (topography of split of the external sagittal crest, shape of mandibular angular process, the presence of intratympanical part of the temporal bone). Absolute craniometrical indices of badger more of indicators of marten, since they directly depend on the weight and body size of these animals. There are most vary the overall length of the scull (1.69 times; P < 0.001), length of bony palate (1.82 times; P < 0.001), length of the external sagittal crest (3.67 times; P < 0.001), width of bony palate at the level of the first premolar and the last molar (2.33 times; P < 0.001), width of choans on the level of hook-shaped processes of pterygoid bone (1.75 times; P < 0.01), width of choans at the level of the caudal edge of the Palatine bone (2 times; P < 0.05), the total height of the scull (2.36 times; P < 0.001). Most of the relative craniometric indicators of the badger scull, compared with such in martens, are almost the same, due to the close specificity of nutrition and environmental characteristics in natural biocenosis. Due to the well-developed external sagittal crest, the height of the brain relative to the total height of the scull in badger (61.02 ± 4.73%) is 1.51 times less (P < 0.001) than in marten (92 ± 6.12%). The relative length of the external sagittal crest to the total length of the badger scull is 2.17 times longer (P < 0.001) (53.1 ± 3.09 versus 24.42 ± 1.41%), compared with marten, due to the more powerful development of masticatory muscles, temporal in particular.
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Fountain, Daniel M., and Tatjana Sauka-Spengler. "The SWI/SNF Complex in Neural Crest Cell Development and Disease." Annual Review of Genomics and Human Genetics 24, no. 1 (2023): 203–23. http://dx.doi.org/10.1146/annurev-genom-011723-082913.
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While the neural crest cell population gives rise to an extraordinary array of derivatives, including elements of the craniofacial skeleton, skin pigmentation, and peripheral nervous system, it is today increasingly recognized that Schwann cell precursors are also multipotent. Two mammalian paralogs of the SWI/SNF (switch/sucrose nonfermentable) chromatin-remodeling complexes, BAF (Brg1-associated factors) and PBAF (polybromo-associated BAF), are critical for neural crest specification during normal mammalian development. There is increasing evidence that pathogenic variants in components of the BAF and PBAF complexes play central roles in the pathogenesis of neural crest–derived tumors. Transgenic mouse models demonstrate a temporal window early in development where pathogenic variants in Smarcb1 result in the formation of aggressive, poorly differentiated tumors, such as rhabdoid tumors. By contrast, later in development, homozygous inactivation of Smarcb1 requires additional pathogenic variants in tumor suppressor genes to drive the development of differentiated adult neoplasms derived from the neural crest, which have a comparatively good prognosis in humans.
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Gomez, Gustavo A., Maneeshi S. Prasad, Nabjot Sandhu, Patrick B. Shelar, Alan W. Leung, and Martín I. García-Castro. "Human neural crest induction by temporal modulation of WNT activation." Developmental Biology 449, no. 2 (2019): 99–106. http://dx.doi.org/10.1016/j.ydbio.2019.02.015.
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Santagati, F. "Temporal requirement of Hoxa2 in cranial neural crest skeletal morphogenesis." Development 132, no. 22 (2005): 4927–36. http://dx.doi.org/10.1242/dev.02078.
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Rekler, Dina, and Chaya Kalcheim. "From Neural Crest to Definitive Roof Plate: The Dynamic Behavior of the Dorsal Neural Tube." International Journal of Molecular Sciences 22, no. 8 (2021): 3911. http://dx.doi.org/10.3390/ijms22083911.
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Research on the development of the dorsal neural tube is particularly challenging. In this highly dynamic domain, a temporal transition occurs between early neural crest progenitors that undergo an epithelial-to-mesenchymal transition and exit the neural primordium, and the subsequent roof plate, a resident epithelial group of cells that constitutes the dorsal midline of the central nervous system. Among other functions, the roof plate behaves as an organizing center for the generation of dorsal interneurons. Despite extensive knowledge of the formation, emigration and migration of neural crest progenitors, little is known about the mechanisms leading to the end of neural crest production and the transition into a roof plate stage. Are these two mutually dependent or autonomously regulated processes? Is the generation of roof plate and dorsal interneurons induced by neural tube-derived factors throughout both crest and roof plate stages, respectively, or are there differences in signaling properties and responsiveness as a function of time? In this review, we discuss distinctive characteristics of each population and possible mechanisms leading to the shift between the above cell types.
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JIANG, LEI, MARC PERLIN, and WILLIAM W. SCHULTZ. "Period tripling and energy dissipation of breaking standing waves." Journal of Fluid Mechanics 369 (August 25, 1998): 273–99. http://dx.doi.org/10.1017/s0022112098001785.
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We examine the dynamics of two-dimensional steep and breaking standing waves generated by Faraday-wave resonance. Jiang et al. (1996) found a steep wave with a double-peaked crest in experiments and a sharp-crested steep wave in computations. Both waveforms are strongly asymmetric in time and feature large superharmonics. We show experimentally that increasing the forcing amplitude further leads to breaking waves in three recurrent modes (period tripling): sharp crest with breaking, dimpled or flat crest with breaking, and round crest without breaking. Interesting steep waveforms and period-tripled breaking are related directly to the nonlinear interaction between the fundamental mode and the second temporal harmonic. Unfortunately, these higher-amplitude phenomena cannot be numerically modelled since the computations fail for breaking or nearly breaking waves. Based on the periodicity of Faraday waves, we directly estimate the dissipation due to wave breaking by integrating the support force as a function of the container displacement. We find that the breaking events (spray, air entrainment, and plunging) approximately double the wave dissipation.
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Kanzler, B., R. K. Foreman, P. A. Labosky, and M. Mallo. "BMP signaling is essential for development of skeletogenic and neurogenic cranial neural crest." Development 127, no. 5 (2000): 1095–104. http://dx.doi.org/10.1242/dev.127.5.1095.
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BMP signaling is essential for a wide variety of developmental processes. To evaluate the role of Bmp2/4 in cranial neural crest (CNC) formation or differentiation after its migration into the branchial arches, we used Xnoggin to block their activities in specific areas of the CNC in transgenic mice. This resulted in depletion of CNC cells from the targeted areas. As a consequence, the branchial arches normally populated by the affected neural crest cells were hypomorphic and their skeletal and neural derivatives failed to develop. In further analyses, we have identified Bmp2 as the factor required for production of migratory cranial neural crest. Its spatial and temporal expression patterns mirror CNC emergence and Bmp2 mutant embryos lack both branchial arches and detectable migratory CNC cells. Our results provide functional evidence for an essential role of BMP signaling in CNC development.
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Ma, Qiumei, Lihua Xiong, Dedi Liu, Chong-Yu Xu, and Shenglian Guo. "Evaluating the Temporal Dynamics of Uncertainty Contribution from Satellite Precipitation Input in Rainfall-Runoff Modeling Using the Variance Decomposition Method." Remote Sensing 10, no. 12 (2018): 1876. http://dx.doi.org/10.3390/rs10121876.
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Satellite precipitation estimates (SPE), characterized by high spatial-temporal resolution, have been increasingly applied to hydrological modeling. However, the errors and bias inherent in SPE are broadly recognized. Yet, it remains unclear to what extent input uncertainty in hydrological models driven by SPE contributes to the total prediction uncertainty, resulting from difficulties in uncertainty partitioning. This study comprehensively quantified the input uncertainty contribution of three precipitation inputs (Tropical Rainfall Measurement Mission (TRMM) near-real-time 3B42RTv7 product, TRMM post-real-time 3B42v7 product and gauge-based precipitation) in rainfall-runoff simulation, using two hydrological models, the lumped daily Ge´nie Rural (GR) and distributed Coupled Routing and Excess STorage (CREST) models. For this purpose, the variance decomposition method was applied to disaggregate the total streamflow modeling uncertainty into seven components (uncertainties in model input, parameter, structure and their three first-order interaction effects, and residual error). The results showed that the total uncertainty in GR was lowest, moderate and highest when forced by gauge precipitation, 3B42v7 and 3B42RTv7, respectively. While the total uncertainty in CREST driven by 3B42v7 was lowest among the three input data sources. These results highlighted the superiority of post-real-time 3B42v7 in hydrological modeling as compared to real-time 3B42RTv7. All the input uncertainties in CREST driven by 3B42v7, 3B42RTv7 and gauge-based precipitation were lower than those in GR correspondingly. In addition, the input uncertainty was lowest in 3B42v7-driven CREST model while highest in gauge precipitation-driven GR model among the six combination schemes (two models combined with three precipitation inputs abovementioned). The distributed CREST model was capable of making better use of the spatial distribution advantage of SPE especially for the TRMM post-real-time 3B42v7 product. This study provided new insights into the SPE’s hydrological utility in the context of uncertainty, being significant for improving the suitability and adequacy of SPE to hydrological application.
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Stone, J. G., L. I. Spirling, and M. K. Richardson. "The neural crest population responding to endothelin-3 in vitro includes multipotent cells." Journal of Cell Science 110, no. 14 (1997): 1673–82. http://dx.doi.org/10.1242/jcs.110.14.1673.
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The peptide endothelin 3 (EDN3) is essential for normal neural crest development in vivo, and is a potent mitogen for quail truncal crest cells in vitro. It is not known which subpopulations of crest cells are targets for this response, although it has been suggested that EDN3 is selective for melanoblasts. In the absence of cell markers for different precursor types in the quail crest, we have characterised EDN3-responsive cell types using in vitro colony assay and clonal analysis. Colonies were analysed for the presence of Schwann cells, melanocytes, adrenergic cells or sensory-like cells. We provide for the first time a description of the temporal pattern of lineage segregation in neural crest cultures. In the absence of exogenous EDN3, crest cells proliferate and then differentiate. Colony assay indicates that in these differentiated cultures few undifferentiated precursors remain and there is a low replating efficiency. By contrast, in the presence of 100 ng/ml EDN3 differentiation is inhibited and most of the cells maintain the ability to give rise to mixed colonies and clones containing neural crest derivatives. A high replating efficiency is maintained. In secondary culture there was a progressive decline in the number of cell types per colony in control medium. This loss of developmental potential was not seen when exogenous EDN3 was present. Cell type analysis suggests two novel cellular targets for EDN3 under these conditions. Contrary to expectations, one is a multipotent precursor whose descendants include melanocytes, adrenergic cells and sensory-like cells; the other can give rise to melanocytes and Schwann cells. Our data do not support previous claims that the action of EDN3 in neural crest culture is selective for cells in the melanocyte lineage.
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Li, Zhansheng, Yuan Yang, Guangyuan Kan, and Yang Hong. "Study on the Applicability of the Hargreaves Potential Evapotranspiration Estimation Method in CREST Distributed Hydrological Model (Version 3.0) Applications." Water 10, no. 12 (2018): 1882. http://dx.doi.org/10.3390/w10121882.
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The potential evapotranspiration (PET) is an important input to the hydrological model and its compatibility has an important influence on the model applications. The applicability of the Hargreaves-Samani (HS) PET estimation method in Coupled Routing and Excess STorage distributed hydrological model version 3.0 (CREST 3.0 model) was studied in a typical humid region, Ganjiang River Basin, in Southern China. The PET estimation methods were evaluated based on the streamflow simulation accuracies using the CREST 3.0 model driven by different PET products with various spatial resolutions. The Penman-Monteith (PM) equation-based PET estimation method was adopted as the reference PET estimation method in this study. The results demonstrated that PET obtained from the HS method was larger than that generated by the PM method, and the CREST 3.0 model driven by both HS and PM-based PET products can simulate the streamflow temporal variations equally well in annual time scale. Compared with the PM method, the HS method was more stable and robust in driving CREST 3.0 model under the scenarios of different spatial resolutions. In addition, during the validation period (2007–2009) with 2003–2006 as the calibration period, the HS outperformed PM considering the streamflow simulation accuracy. Therefore, the HS method was not only applicable to CREST 3.0 model with flexible spatial resolutions, but also can be an alternative method to PM method in CREST 3.0 model streamflow simulation applications in Ganjiang River Basin. The study results will not only increase the confidence on the applicability of the HS method in hydrological simulation in Ganjiang River Basin, but also prove the flexibility of CREST 3.0 model in terms of PET input, which will expand the application range of the CREST 3.0 model.
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Rama Rao, P. V. S., S. Gopi Krishna, K. Niranjan, and D. S. V. V. D. Prasad. "Temporal and spatial variations in TEC using simultaneous measurements from the Indian GPS network of receivers during the low solar activity period of 2004–2005." Annales Geophysicae 24, no. 12 (2006): 3279–92. http://dx.doi.org/10.5194/angeo-24-3279-2006.
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Abstract. With the recent increase in the satellite-based navigation applications, the ionospheric total electron content (TEC) and the L-band scintillation measurements have gained significant importance. In this paper we present the temporal and spatial variations in TEC derived from the simultaneous and continuous measurements made, for the first time, using the Indian GPS network of 18 receivers located from the equator to the northern crest of the equatorial ionization anomaly (EIA) region and beyond, covering a geomagnetic latitude range of 1° S to 24° N, using a 16-month period of data for the low sunspot activity (LSSA) years of March 2004 to June 2005. The diurnal variation in TEC at the EIA region shows its steep increase and reaches its maximum value between 13:00 and 16:00 LT, while at the equator the peak is broad and occurs around 16:00 LT. A short-lived day minimum occurs between 05:00 to 06:00 LT at all the stations from the equator to the EIA crest region. Beyond the crest region the day maximum values decrease with the increase in latitude, while the day minimum in TEC is flat during most of the nighttime hours, i.e. from 22:00 to 06:00 LT, a feature similar to that observed in the mid-latitudes. Further, the diurnal variation in TEC show a minimum to maximum variation of about 5 to 50 TEC units, respectively, at the equator and about 5 to 90 TEC units at the EIA crest region, which correspond to range delay variations of about 1 to 8 m at the equator to about 1 to 15 m at the crest region, at the GPS L1 frequency of 1.575 GHz. The day-to-day variability is also significant at all the stations, particularly during the daytime hours, with maximum variations at the EIA crest regions. Further, similar variations are also noticed in the corresponding equatorial electrojet (EEJ) strength, which is known to be one of the major contributors for the observed day-to-day variability in TEC. The seasonal variation in TEC maximizes during the equinox months followed by winter and is minimum during the summer months, a feature similar to that observed in the integrated equatorial electrojet (IEEJ) strength for the corresponding seasons. In the Indian sector, the EIA crest is found to occur in the latitude zone of 15° to 25° N geographic latitudes (5° to 15° N geomagnetic latitudes). The EIA also maximizes during equinoxes followed by winter and is not significant in the summer months in the LSSA period, 2004–2005. These studies also reveal that both the location of the EIA crest and its peak value in TEC are linearly related to the IEEJ strength and increase with the increase in IEEJ.
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Yalcin, E. D., and S. Akyol. "Assessment of the temporal crest canal using cone-beam computed tomography." British Journal of Oral and Maxillofacial Surgery 58, no. 2 (2020): 199–202. http://dx.doi.org/10.1016/j.bjoms.2019.11.012.
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Hari, L., I. Miescher, O. Shakhova, et al. "Temporal control of neural crest lineage generation by Wnt/ -catenin signaling." Development 139, no. 12 (2012): 2107–17. http://dx.doi.org/10.1242/dev.073064.
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Landolt, R. M., L. Vaughan, K. H. Winterhalter, and D. R. Zimmermann. "Versican is selectively expressed in embryonic tissues that act as barriers to neural crest cell migration and axon outgrowth." Development 121, no. 8 (1995): 2303–12. http://dx.doi.org/10.1242/dev.121.8.2303.
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Chondroitin sulfate proteoglycans have been implicated in the regulation of cell migration and pattern formation in the developing peripheral nervous system. To identify whether the large aggregating proteoglycan versican might be mediating these processes, we prepared monospecific antibodies against a recombinant core protein fragment of chick versican. The purified antibodies recognize the predominant versican splice-variants V0 and V1. Using these antibodies, we revealed a close correlation between the spacio-temporal expression of versican and the formation of molecular boundaries flanking or transiently blocking the migration pathways of neural crest cells or motor and sensory axons. Versican is present in the caudal sclerotome, the early dorsolateral tissue underneath the ectoderm, the pelvic girdle precursor and to a certain extent in the perinotochordal mesenchyme. Versican is completely absent from tissues invaded by neural crest cells and extending axons. Upon completion of neural crest cell migration and axon outgrowth, versican expression is shifted to pre-chondrogenic areas. Since versican inhibits cellular interactions with fibronectin, laminin and collagen I in vitro, the selective expression of versican within barrier tissues may be linked to a functional role of versican in the guidance of migratory neural crest cells and outgrowing axons.
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SCHULTZ, WILLIAM W., JEAN-MARC VANDEN-BROECK, LEI JIANG, and MARC PERLIN. "Highly nonlinear standing water waves with small capillary effect." Journal of Fluid Mechanics 369 (August 25, 1998): 253–72. http://dx.doi.org/10.1017/s0022112098001773.
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We calculate spatially and temporally periodic standing waves using a spectral boundary integral method combined with Newton iteration. When surface tension is neglected, the non-monotonic behaviour of global wave properties agrees with previous computations by Mercer & Roberts (1992). New accurate results near the limiting form of gravity waves are obtained by using a non-uniform node distribution. It is shown that the crest angle is smaller than 90° at the largest calculated crest curvature. When a small amount of surface tension is included, the crest form is changed significantly. It is necessary to include surface tension to numerically reproduce the steep standing waves in Taylor's (1953) experiments. Faraday-wave experiments in a large-aspect-ratio rectangular container agree with our computations. This is the first time such high-amplitude, periodic waves appear to have been observed in laboratory conditions. Ripple formation and temporal symmetry breaking in the experiments are discussed.
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Lough, R. Gregory, Elisabeth A. Broughton, and Trond Kristiansen. "Changes in spatial and temporal variability of prey affect functional connectivity of larval and juvenile cod." ICES Journal of Marine Science 74, no. 6 (2017): 1826–37. http://dx.doi.org/10.1093/icesjms/fsx080.
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Abstract Changes in structural connectivity as it can affect functional connectivity, the biological and behavioural responses of an organism, has been examined here over 2 contrasting years when the spatial distribution of larval and juvenile cod and their prey shifted from the flank to the crest on Georges Bank. New data on the gut contents of pelagic juvenile cod are compared with known prey distributions, potential growth and how climate warming can change connectivity in this region. Centropages spp. was the most important prey for pelagic juveniles, especially in June 1987 when they had high abundance on the crest and were dominant in the cod stomachs. In June 1986, copepod abundance was low where the juveniles were distributed along the flank. The potential growth of juvenile cod was greater in June 1987, consistent with the higher abundance of Centropages spp., and with higher recruitment survival, compared with June 1986. Annual changes in the spatial distribution of cod early life stages within the environment of cold or warm years can have different impacts on their growth and survival. Whereas the small copepods, Pseudocalanus spp., are primary prey for cod larvae and very abundant in cold years, larger copepods, Calanus finmarchicus and Centropages spp., are important prey for the pelagic juveniles and the latter species can have a high impact in warm years on the crest. The different spatial structure during cold or warm years provides an explanation why different year classes respond differently to environmental change. Depending on the presence or absence of specific prey, the functional connectivity response changes pathways that determine the growth and survival of early life stages and ultimately a role in recruitment.
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Anderson, R. Scott, Susan J. Smith, and Peter A. Koehler. "Distribution of Sites and Radiocarbon Dates in the Sierra Nevada: Implications for Paleoecological Prospecting." Radiocarbon 39, no. 2 (1997): 121–37. http://dx.doi.org/10.1017/s0033822200051973.
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The number of paleoecological records for the Sierra Nevada of California has increased substantially since the compilation of Adam (1985). We examine here the geographical and temporal distribution of records within the range in order to identify areas for which “gaps” exist in our paleoecological knowledge. Seventy-two sites with paleoecological information are identified; these sites are dated with 234 radiocarbon dates. Sites occur primarily between ca. 36°N and 38°30'N latitudes, and from ca. 1000 m to over 3000 m elevation on both sides of the Sierran crest, although more sites have been analyzed on the west side of the crest than the east side. In general, packrat (Neotoma) midden series are located at the lowest elevations, meadow and marsh cores originate from mid-elevations, and lake sediments have been analyzed from the highest elevations. Significant gaps in our knowledge occur for much of the east side of the crest, for both sides of the range above modern treeline, and for time periods older than the latest Pleistocene.
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Serbedzija, G. N., M. Bronner-Fraser, and S. E. Fraser. "Vital dye analysis of cranial neural crest cell migration in the mouse embryo." Development 116, no. 2 (1992): 297–307. http://dx.doi.org/10.1242/dev.116.2.297.
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The spatial and temporal aspects of cranial neural crest cell migration in the mouse are poorly understood because of technical limitations. No reliable cell markers are available and vital staining of embryos in culture has had limited success because they develop normally for only 24 hours. Here, we circumvent these problems by combining vital dye labelling with exo utero embryological techniques. To define better the nature of cranial neural crest cell migration in the mouse embryo, premigratory cranial neural crest cells were labelled by injecting DiI into the amniotic cavity on embryonic day 8. Embryos, allowed to develop an additional 1 to 5 days exo utero in the mother before analysis, showed distinct and characteristic patterns of cranial neural crest cell migration at the different axial levels. Neural crest cells arising at the level of the forebrain migrated ventrally in a contiguous stream through the mesenchyme between the eye and the diencephalon. In the region of the midbrain, the cells migrated ventrolaterally as dispersed cells through the mesenchyme bordered by the lateral surface of the mesencephalon and the ectoderm. At the level of the hindbrain, neural crest cells migrated ventrolaterally in three subectodermal streams that were segmentally distributed. Each stream extended from the dorsal portion of the neural tube into the distal portion of the adjacent branchial arch. The order in which cranial neural crest cells populate their derivatives was determined by labelling embryos at different stages of development. Cranial neural crest cells populated their derivatives in a ventral-to-dorsal order, similar to the pattern observed at trunk levels. In order to confirm and extend the findings obtained with exo utero embryos, DiI (1,1-dioctadecyl-3,3,3′,3′-tetramethylindo-carbocyanine perchlorate) was applied focally to the neural folds of embryos, which were then cultured for 24 hours. Because the culture technique permitted increased control of the timing and location of the DiI injection, it was possible to determine the duration of cranial neural crest cell emigration from the neural tube. Cranial neural crest cell emigration from the neural folds was completed by the 11-somite stage in the region of the rostral hindbrain, the 14-somite stage in the regions of the midbrain and caudal hindbrain and not until the 16-somite stage in the region of the forebrain. At each level, the time between the earliest and latest neural crest cells to emigrate from the neural tube appeared to be 9 hours.(ABSTRACT TRUNCATED AT 400 WORDS)
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Ossenberg, N. S. "Temporal crest canal: Case report and statistics on a rare mandibular variant." Oral Surgery, Oral Medicine, Oral Pathology 62, no. 1 (1986): 10–12. http://dx.doi.org/10.1016/0030-4220(86)90062-9.
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Shin, Myung K., John M. Levorse, Robert S. Ingram, and Shirley M. Tilghman. "The temporal requirement for endothelin receptor-B signalling during neural crest development." Nature 402, no. 6761 (1999): 496–501. http://dx.doi.org/10.1038/990040.
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Matsuoka, Norikazu. "Temporal and spatial variations in periglacial soil movements on alpine crest slopes." Earth Surface Processes and Landforms 30, no. 1 (2005): 41–58. http://dx.doi.org/10.1002/esp.1125.
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Boisseau, S., J. Nedelec, V. Poirier, G. Rougon, and M. Simonneau. "Analysis of high PSA N-CAM expression during mammalian spinal cord and peripheral nervous system development." Development 112, no. 1 (1991): 69–82. http://dx.doi.org/10.1242/dev.112.1.69.
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Using a monoclonal antibody that recognizes specifically a high polysialylated form of N-CAM (high PSA N-CAM), the temporal and spatial expression of this molecule was studied in developing spinal cord and neural crest derivatives of mouse truncal region. Temporal expression was analyzed on immunoblots of spinal cord and dorsal root ganglia (DRGs) extracts microdissected at different developmental stages. Analysis of the ratio of high PSA N-CAM to total N-CAM indicated that sialylation and desialylation are independently regulated from the expression of polypeptide chains of N-CAM. Motoneurons, dorsal root ganglia cells and commissural neurons present a homogeneous distribution of high PSA N-CAMs on both their cell bodies and their neurites. Sialylation of N-CAM can occur in neurons after their aggregation in peripheral ganglia as demonstrated for dorsal root ganglia at E12. Furthermore, peripheral ganglia express different levels of high PSA N-CAM. With in vitro models using mouse neural crest cells, we found that expression of high PSA N-CAM was restricted to cells presenting an early neuronal phenotype, suggesting a common regulation for the expression of high PSA N-CAM molecules, neurofilament proteins and sodium channels. Using perturbation experiments with endoneuraminidase, we confirmed that high PSA N-CAM molecules are involved in fasciculation and neuritic growth when neurons derived from neural crest grow on collagen substrata. However, we demonstrated that these two parameters do not appear to depend on high PSA N-CAM molecules when cells were grown on a fibronectin substratum, indicating the existence of a hierarchy among adhesion molecules.
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Li, Bin, Phi Doan, Robert R. Gruhl, Alessia Rubini, Daniele Marchioni, and Manuela Fina. "Endoscopic Anatomy of the Tensor Fold and Anterior Attic." Otolaryngology–Head and Neck Surgery 158, no. 2 (2017): 358–63. http://dx.doi.org/10.1177/0194599817739295.
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Objectives The objectives of the study were to (1) study the anatomical variations of the tensor fold and its anatomic relation with transverse crest, supratubal recess, and anterior epitympanic space and (2) explore the most appropriate endoscopic surgical approach to each type of the tensor fold variants. Study Design Cadaver dissection study. Setting Temporal bone dissection laboratory. Subjects and Methods Twenty-eight human temporal bones (26 preserved and 2 fresh) were dissected through an endoscopic transcanal approach between September 2016 and June 2017. The anatomical variations of the tensor fold, transverse crest, supratubal recess, and anterior epitympanic space were studied before and after removing ossicles. Results Three different tensor fold orientations were observed: vertical (type A, 11/28, 39.3%) with attachment to the transverse crest, oblique (type B, 13/28, 46.4%) with attachment to the anterior tegmen tympani, and horizontal (type C, 4/28, 14.3%) with attachment to the tensor tympani canal. The tensor fold was a complete membrane in 20 of 28 (71.4%) specimens, preventing direct ventilation between the supratubal recess and anterior epitympanic space. We identified 3 surgical endoscopic approaches, which allowed visualization of the tensor fold without removing the ossicles. Conclusions The orientation of the tensor fold is the determining structure that dictates the conformation and limits of the epitympanic space. We propose a classification of the tensor fold based on 3 anatomical variants. We also describe 3 different minimally invasive endoscopic approaches to identify the orientation of the tensor fold while maintaining ossicular chain continuity.
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van, Haren Hans, Ulrike Hanz, Stigter Henko de, Furu Mienis, and Gerard Duineveld. "Internal wave turbulence at a biologically rich Mid-Atlantic seamount." PLoS ONE 12, no. 12 (2017): e0189720. https://doi.org/10.1371/journal.pone.0189720.
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<strong>Abstract</strong> The turbulence regime near the crest of a biologically rich seamount of the Mid-Atlantic Ridge southwest of the Azores was registered in high spatial and temporal resolution. Internal tides and their higher harmonics dominate the internal wave motions, producing considerable shear-induced turbulent mixing in layers of 10–50 m thickness. This interior mixing of about 100 times open-ocean interior values is observed both at a high-resolution temperature sensor mooring-site at the crest, 770 m water depth being nearly 400 m below the top of the seamount, and a CTD-yoyo site at the slope off the crest 400 m horizontally away, 880 m water depth. Only at the mooring site, additionally two times higher turbulence is observed near the bottom, associated with highly non-linear wave breaking. The highest abundance of epifauna, notably sponges, are observed just below the crest and 100 m down the eastern slope (700–800 m) in a cross-ridge video-camera transect. This sponge belt is located in a water layer of depressed oxygen levels (saturation 63±2%) with a local minimum centered around 700 m. Turbulent mixing supplies oxygen to this region from above and below and is expected to mix nutrients away from this biodegraded layer towards the depth of highest abundance of macrofauna.
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Jiang, Lei, Chao-Lung Ting, Marc Perlin, and William W. Schultz. "Moderate and steep Faraday waves: instabilities, modulation and temporal asymmetries." Journal of Fluid Mechanics 329 (December 25, 1996): 275–307. http://dx.doi.org/10.1017/s0022112096008920.
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Mild to steep standing waves of the fundamental mode are generated in a narrow rectangular cylinder undergoing vertical oscillation with forcing frequencies of 3.15 Hz to 3.34 Hz. A precise, non-intrusive optical wave profile measurement system is used along with a wave probe to accurately quantify the spatial and temporal surface elevations. These standing waves are also simulated by a two-dimensional spectral Cauchy integral code. Experiments show that contact-line effects increase the viscous natural frequency and alter the neutral stability curves. Hence, as expected, the addition of the wetting agent Photo Flo significantly changes the stability curve and the hysteresis in the response diagram. Experimentally, we find strong modulations in the wave amplitude for some forcing frequencies higher than 3.30 Hz. Reducing contact-line effects by Photo-Flo addition suppresses these modulations. Perturbation analysis predicts that some of this modulation is caused by noise in the forcing signal through ‘sideband resonance’, i.e. the introduction of small sideband forcing can generate large modulations of the Faraday waves. The analysis is verified by our numerical simulations and physical experiments. Finally, we observe experimentally a new form of steep standing wave with a large symmetric double-peaked crest, while simulation of the same forcing condition results in a sharper crest than seen previously. Both standing wave forms appear at a finite wave steepness far smaller than the maximum steepness for the classical standing wave and a surface tension far smaller than that for a Wilton ripple. In both physical and numerical experiments, a stronger second harmonic (in time) and temporal asymmetry in the wave forms suggest a 1:2 resonance due to a non-conventional quartet interaction. Increasing wave steepness leads to a new form of breaking standing waves in physical experiments.
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Pinheiro, Felipe L., and Taissa Rodrigues. "Anhanguera taxonomy revisited: is our understanding of Santana Group pterosaur diversity biased by poor biological and stratigraphic control?" PeerJ 5 (May 4, 2017): e3285. http://dx.doi.org/10.7717/peerj.3285.
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Background Anhanguerids comprise an important clade of pterosaurs, mostly known from dozens of three-dimensionally preserved specimens recovered from the Lower Cretaceous Romualdo Formation (northeastern Brazil). They are remarkably diverse in this sedimentary unit, with eight named species, six of them belonging to the genus Anhanguera. However, such diversity is likely overestimated, as these species have been historically diagnosed based on subtle differences, mainly based on the shape and position of the cranial crest. In spite of that, recently discovered pterosaur taxa represented by large numbers of individuals, including juveniles and adults, as well as presumed males and females, have crests of sizes and shapes that are either ontogenetically variable or sexually dimorphic. Methods We describe in detail the skull of one of the most complete specimens referred to Anhanguera, AMNH 22555, and use it as a case study to review the diversity of anhanguerids from the Romualdo Formation. In order to accomplish that, a geometric morphometric analysis was performed to assess size-dependent characters with respect to the premaxillary crest in the 12 most complete skulls bearing crests that are referred in, or related to, this clade, almost all of them analyzed first hand. Results Geometric morphometric regression of shape on centroid size was highly statistically significant (p = 0.0091) and showed that allometry accounts for 25.7% of total shape variation between skulls of different centroid sizes. Premaxillary crests are both taller and anteroposteriorly longer in larger skulls, a feature consistent with ontogenetic growth. A new diagnosis is proposed for Anhanguera, including traits that are nowadays known to be widespread within the genus, as well as ontogenetic changes. AMNH 22555 cannot be referred to “Anhanguera santanae” and, in fact, “Anhanguera santanae”, “Anhanguera araripensis”, and “Anhanguera robustus” are here considered nomina dubia. Discussion Historically, minor differences in crest morphology have been used in the definition of new anhanguerid species. Nowadays, this practice resulted in a considerable difficulty in referring well-preserved skulls into known taxa. When several specimens are analyzed, morphologies previously believed to be disparate are, in fact, separated by a continuum, and are thus better explained as individual or temporal variations. Stratigraphically controlled excavations on the Romualdo Formation have showed evidence for faunal turnover regarding fish communities. It is thus possible that some of the pterosaurs from this unit were not coeval, and might even represent anagenetic morphotypes. Unfortunately, amateur collecting of Romualdo Formation fossils, aimed especially at commerce, resulted in the lack of stratigraphic data of virtually all its pterosaurs and precludes testing of these further hypotheses.
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Perfit, M. R., D. J. Fornari, M. C. Smith, J. F. Bender, C. H. Langmuir, and R. M. Haymon. "Small-scale spatial and temporal variations in mid-ocean ridge crest magmatic processes." Geology 22, no. 4 (1994): 375–79. http://dx.doi.org/10.1130/0091-7613(1994)022<0375:sssatv>2.3.co;2.
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Hummon, Julia M., and Thomas Rossby. "Spatial and temporal evolution of a Gulf Stream crest-warm core ring interaction." Journal of Geophysical Research: Oceans 103, no. C2 (1998): 2795–809. http://dx.doi.org/10.1029/97jc02375.
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Porras, Diego, and Christopher B. Brown. "Temporal–spatial ablation of neural crest in the mouse results in cardiovascular defects." Developmental Dynamics 237, no. 1 (2007): 153–62. http://dx.doi.org/10.1002/dvdy.21382.
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Kent, Marc, Eric N. Glass, and Jordan Schachar. "A lateral approach to the feline cerebellar fossa: case report and identification of an external landmark for the tentorium ossium." Journal of Feline Medicine and Surgery 22, no. 4 (2019): 358–65. http://dx.doi.org/10.1177/1098612x19869699.
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Objectives The aim of this study was to describe the use of an external landmark that defines the attachment of the tentorium ossium for planning a craniectomy to access the cerebellar fossa. The external landmark was defined by a line where the caudal aspect of the convexity of the cranium transitions to a flat surface in the caudal aspect of the temporal fossa. We also aimed to determine if this external landmark was present and readily visualized, and to establish its relationship to the nuchal crest using three-dimensional (3D) volume-rendered CT reconstructions created from cats with normal cranial morphology. Methods First, a case is presented for the description of an approach in a cat with a meningioma located dorsolateral to the cerebellum. Second, CT studies of five cats with normal cranial morphology were selected. Regions of interest (ROIs) were drawn at the attachment of the tentorium ossium to the cranium and nuchal crest. Three-dimensional reconstructions were developed with colored ROI overlays. The external landmark defined the tentorial attachment on all 3D reconstructions. Additionally, using the postoperative CT of the clinical case described herein, ROIs of the tentorial attachment and nuchal crest along with a third ROI, the craniectomy, were drawn and overlaid on the 3D reconstruction to illustrate the position of the craniectomy in relation to the tentorium ossium attachment and nuchal crest. Results The use of the external landmark provided for a craniectomy that enabled adequate visualization for excision of a meningioma. On all 3D reconstructions, the external landmark was present and readily visualized. Conclusions and relevance Between the attachment of the tentorium ossium and nuchal crest exists an area adequately sized for a craniectomy in cats. Clinicians can use an identifiable external landmark on the lateral aspect of the cranium to plan the rostral boundary for a craniectomy to access the cerebellar fossa in cats.
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Psuty, Norbert, Katherine Ames, Andrea Habeck, and Glenn Liu. "Sediment Budget and Geomorphological Evolution of the Estuarine Dune-Beach System on Three Nourished Beaches, Delaware Bay, New Jersey." Geosciences 9, no. 1 (2018): 16. http://dx.doi.org/10.3390/geosciences9010016.
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Beach nourishment was applied at three fetch-restricted sites along the estuarine margin of Delaware Bay, New Jersey. Evaluation of geomorphological performance of the nourishment project was conducted through seasonal monitoring to track linear features (shoreline, dune crest, peat edge) and to create digital elevation models (DEMs). Comparisons of the DEMs yielded sediment budgets of the updrift, fill area, and downdrift zones as well as the spatial and temporal evolution of the tidal flat, beach, and dune features within the zones. Through four years, Moore’s Beach lost all of the emplaced fill as well as an additional −5446 m3 from the fill area. The shoreline position shifted inland −12.78 m, and the foredune crest shifted inland −9.23 m. The fill area at Pierce’s Point lost all of the fill and an additional −3810 m3. The shoreline and dune crest shifted inland −7.35 m and −1.17 m, respectively. The Reed’s Beach study area benefited from beach fill updrift that more than offset the losses in the fill area, a net gain of 2107 m3. There was a major contrast in volumetric change between the updrift and downdrift portions. Sediment budget calculations established alongshore transport was an important factor in the fetch-restricted estuarine environment driving the variable geomorphological responses in the updrift, fill, and downdrift zones.
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Takahashi, K., G. H. Nuckolls, O. Tanaka, et al. "Adenovirus-mediated ectopic expression of Msx2 in even-numbered rhombomeres induces apoptotic elimination of cranial neural crest cells in ovo." Development 125, no. 9 (1998): 1627–35. http://dx.doi.org/10.1242/dev.125.9.1627.
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Distinct cranial neural crest-derived cell types (a number of neuronal as well as non-neuronal cell lineages) are generated at characteristic times and positions in the rhombomeres of the hindbrain in developing vertebrate embryos. To examine this developmental process, we developed a novel strategy designed to test the efficacy of gain-of-function Msx2 expression within rhombomeres in ovo prior to the emigration of cranial neural crest cells (CNCC). Previous studies indicate that CNCC from odd-numbered rhombomeres (r3 and r5) undergo apoptosis in response to exogenous BMP4. We provide evidence that targeted infection in ovo using adenovirus containing Msx2 and a reporter molecule indicative of translation can induce apoptosis in either even- or odd-numbered rhombomeres. Furthermore, infected lacZ-control explants indicated that CNCC emigrated, and that 20% of these cells were double positive for crest cell markers HNK-1 and beta-gal. In contrast, there were no HNK-1 and Msx2 double positive cells emigrating from Msx2 infected explants. These results support the hypothesis that apoptotic elimination of CNCC can be induced by ‘gain-of-function’ Msx2 expression in even-numbered rhombomeres. These inductive interactions involve qualitative, quantitative, positional and temporal differences in TGF-beta-related signals, Msx2 expression and other transcriptional control.
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Kumar, Navneet, Rakesh Kumar Verma, Arvind Kumar Pankaj, Archana Rani, and Rakesh Kumar Diwan. "Bilateral bony bar bridging of the sigmoid sulcus : a case report." National Journal of Clinical Anatomy 05, no. 02 (2016): 097–99. http://dx.doi.org/10.1055/s-0039-3401593.
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AbstractThe crest, plate and bars like bony projections may be present on sigmoid sulcus. The bony connection between petrous temporal and occipital bone may divide the jugnlar foramen. A skull with bilateral curved bony plate connecting the inner margin of groove for sigmoid sinus and petrous temporal was observed during routine osteology classes. The shape, size and location of both the bars were almost identical. These bony bars were connecting the posterior margin of petrous temporal and postero-lateral part of sigmoid sulcus. Structurally, they resembled as a part of ring. The location of the bar was more lateral on left side as compared to right side. Some bony erosion was also seen in the floor of sigmrid sulcus. Bilateral ossification and formation of bar at sigmoid sulcus is associated with venous sinus anomalies, dural ossification and intracranial calcifications.
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Pasqualetti, M., M. Ori, I. Nardi, and F. M. Rijli. "Ectopic Hoxa2 induction after neural crest migration results in homeosis of jaw elements in Xenopus." Development 127, no. 24 (2000): 5367–78. http://dx.doi.org/10.1242/dev.127.24.5367.
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Hox genes are required to pattern neural crest (NC) derived craniofacial and visceral skeletal structures. However, the temporal requirement of Hox patterning activity is not known. Here, we use an inducible system to establish Hoxa2 activity at distinct NC migratory stages in Xenopus embryos. We uncover stage-specific effects of Hoxa2 gain-of-function suggesting a multistep patterning process for hindbrain NC. Most interestingly, we show that Hoxa2 induction at postmigratory stages results in mirror image homeotic transformation of a subset of jaw elements, normally devoid of Hox expression, towards hyoid morphology. This is the reverse phenotype to that observed in the Hoxa2 knockout. These data demonstrate that the skeletal pattern of rhombomeric mandibular crest is not committed before migration and further implicate Hoxa2 as a true selector of hyoid fate. Moreover, the demonstration that the expression of Hoxa2 alone is sufficient to transform the upper jaw and its joint selectively may have implications for the evolution of jaws.
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Chonnaniyah, Chonnaniyah, Takahiro Osawa, and I. Wayan Gede Astawa Karang. "STUDY OF INTERNAL SOLITARY WAVES FEATURE EXTRACTION BASED ON STATIONARY WAVELET TRANSFORM BY SENTINEL-1A IMAGE IN LOMBOK STRAIT." ECOTROPHIC : Jurnal Ilmu Lingkungan (Journal of Environmental Science) 13, no. 1 (2019): 29. http://dx.doi.org/10.24843/ejes.2019.v13.i01.p04.
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Stationary Wavelet Transform (SWT), mother function Symlet 4, shows an effective method for Internal Solitary Waves (ISW) feature extraction and four parameters (soliton numbers, first crest length, wavelength and propagation direction) estimation by Sentinel-1A C-band Synthetic Aperture Radar (SAR) imagery in Lombok Strait. The ISW feature can be distinguished from other features using the SWT noise reduction process and simple thresholding methods. ISW feature extraction results by SAR images can show ISW characteristics more clearly and can be used as a basis for obtaining ISW spatial-temporal distribution maps in the Lombok Strait. Our estimation results show that the arc-like type of ISW in the Lombok Strait propagated to the north of the sill with the detected soliton numbers are 2 solitons per packets with a wavelength about 3.20 km and the first crest length varies about 60.27 km near the Kangean Island with the propagation direction about 50.38 degree to the North.
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Supawannawiwat, Thanawan, Chottiwat Tansirisithikul, and Bunpot Sitthinamsuwan. "Temporal Bone Landmarks of the Transversesigmoid Sinus Junction: An Anatomical Study in Dried Human Skulls." Siriraj Medical Journal 73, no. 11 (2021): 738–43. http://dx.doi.org/10.33192/smj.2021.95.
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Objective: To investigate the accuracy in localization of the anterosuperior margin of TSSJ by using the intersection point between the squamosal and parietomastoid sutures (A point) and the intersection of the squamosal suture and supramastoid crest (B point) as bony landmarks.Materials and Methods: The A and B points were marked on the inner surface of a skull by using the transillumination technique. The anatomical relationship between the projected A point, B point, and groove of TSSJ was investigated in 60 dried Thai human skulls (120 sides).Results: Of the 120 sides, the projected A points were located exactly on the anterosuperior margin of the TSSJ in 38 (31.7%) instances and adjacent (above and below) the anterosuperior margin in 82 (68.3%) cases. Of the 118 sides with identifiable supramastoid crests, the projected B points were located precisely on the anterosuperior margin of TSSJ in 60 (50.8%) cases and above the anterosuperior margin of the TSSJ in 57 (48.3%) cases. Hence, the projected B point was a more reliable bony landmark for localizing the anterosuperior margin of the TSSJ when compared with the projected A point (p = 0.003, OR 2.2, and 95% CI =1.3-3.8).Conclusion: The B point is a more reliable temporal bone landmark for localization of the TSSJ than the A point. In temporal craniotomy, an initial burr hole at the B point is relatively safe and carries a very low risk of inadvertent venous sinus injury.
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Simms, David L., and J. Gail Neely. "Thickness of the Lateral Surface of the Temporal Bone in Children." Annals of Otology, Rhinology & Laryngology 98, no. 9 (1989): 726–31. http://dx.doi.org/10.1177/000348948909800913.
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The placement of implantable auditory prostheses in children has raised questions concerning the thickness of the temporal bone in the region of implantation. The purpose of this study is to describe the thickness at specific sites of the lateral surface of the temporal bone in children of different ages. One hundred twenty-five intact temporal bones from 83 children of known sex, race, and age between birth and 20 years were measured. Thickness was measured with a specially designed micrometer at specific locations from a fixed reference point by use of a surface projected grid for site identification. Thickness was plotted against age on scattergraphs for each site, and regression analysis revealed a bimodal linear relationship. Sites medial to the temporalis muscle were the thinnest; sites associated with the posteroinferior insertion of the temporalis muscle, along the supramastoid crest, were the thickest. However, wide interindividual variability was the rule.
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McKeown, Sonja J., Donald F. Newgreen, and Peter G. Farlie. "Temporal restriction of migratory and lineage potential in rhombomere 1 and 2 neural crest." Developmental Biology 255, no. 1 (2003): 62–76. http://dx.doi.org/10.1016/s0012-1606(02)00076-3.
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Ali, Asha, Steven Lo, Charles Nduka, and Philip Adds. "Anatomy of the infratemporal crest: Implications for cross-facial nerve grafting in temporal myoplasty." Journal of Plastic, Reconstructive & Aesthetic Surgery 65, no. 3 (2012): e54-e59. http://dx.doi.org/10.1016/j.bjps.2011.11.028.
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Echelard, Y., G. Vassileva, and A. P. McMahon. "Cis-acting regulatory sequences governing Wnt-1 expression in the developing mouse CNS." Development 120, no. 8 (1994): 2213–24. http://dx.doi.org/10.1242/dev.120.8.2213.
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The protooncogene Wnt-1 encodes a short-range signal which is first expressed in, and appears to demarcate, the presumptive midbrain. Absence of Wnt-1 expression leads to the loss of this region of the brain. By the end of neural tube closure, expression of Wnt-1 extends down much of the dorsal midline of the central nervous system (CNS). Expression is exclusively limited to the CNS at this and later stages. We have investigated the regulation of Wnt-1 during mouse development. Analysis of the embryonic expression of Wnt-1-lacZ reporter constructs spanning nearly 30 kb of the Wnt-1 locus identified a 5.5 kb cis-acting 3′ enhancer element which confers correct temporal and spatial expression on the lacZ gene. Interestingly embryos express Wnt-1-lacZ transgenes in migrating neural crest cells which are derived from the dorsal CNS. Ectopic expression of the Wnt-1-lacZ transgenes may result from perdurance of beta-galactosidase activity in migrating neural crest cells originating from a Wnt-1-expressing region of the dorsal CNS. Alternatively, ectopic expression may arise from transient de novo activation of the transgenes in this cell population. These results are a first step towards addressing how regional cell signaling is established in the mammalian CNS. In addition, transgene expression provides a new tool for the analysis of neural crest development in normal and mutant mouse embryos.
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Alevizos, Evangelos. "Quantification of Nearshore Sandbar Seasonal Evolution Based on Drone Pseudo-Bathymetry Time-Lapse Data." Remote Sensing 16, no. 23 (2024): 4551. https://doi.org/10.3390/rs16234551.
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Nearshore sandbars are dynamic features that characterize shallow morphobathymetry and vary over a wide range of geometries and temporal lifespans. Nearshore sandbars influence beach geometry by altering the energy of incoming waves; thus, monitoring the evolution of sandbars is a fundamental approach in effective coastal planning. Due to several natural and technical limitations related to shallow seafloor mapping, there is a significant gap in the availability of high-resolution, shallow bathymetric data for monitoring the dynamic behaviour of nearshore sandbars effectively. This study introduces a novel image-processing technique that produces time series of pseudo-bathymetric data by utilizing multi-temporal (monthly) drone imagery, and it provides an assessment of local morphodynamics at a sandy beach in the southeast Mediterranean. The technique is called standardized-ratio bathymetric index (SRBI), and it transforms natural-colour drone imagery to pseudo-bathymetric data by applying an empirical formula used for satellite-derived bathymetry. This technique correlates well with laser altimetry depth measurements; however, it does not require in situ depth data for implementation. The resulting pseudo-bathymetric data allows for extracting cross-shore profiles and delineating the sandbar crest with 4 m horizontal accuracy. Stacking of temporal profiles allowed for the quantification of the sandbar’s crest and trough changes at different alongshore sections. The main findings suggest that the nearshore crescentic sandbar at Episkopi Beach (north Crete) shows strong seasonality regarding net offshore migration that is promoted by enhanced wave action during winter months. In addition, the crescentic sandbar is susceptible to morphology arrestment during prolonged weeks of low wave action. The average migration rate during winter is 10 m.month−1, with some sections exhibiting a maximum of 60 m.month−1. This study (a) offers a novel remote-sensing approach, suitable for nearshore seafloor monitoring with low computational complexity, (b) reveals sandbar geometry and temporal change in superior detail compared to other observational methods, and (c) advances knowledge about nearshore sandbar monitoring in the Mediterranean region.
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Maden, M., P. Hunt, U. Eriksson, A. Kuroiwa, R. Krumlauf, and D. Summerbell. "Retinoic acid-binding protein, rhombomeres and the neural crest." Development 111, no. 1 (1991): 35–43. http://dx.doi.org/10.1242/dev.111.1.35.
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We have investigated by immunocytochemistry the spatial and temporal distribution of cellular retinoic acid-binding protein (CRABP) in the developing nervous system of the chick embryo in order to answer two specific questions: do neural crest cells contain CRABP and where and when do CRABP-positive neuroblasts first arise in the neural tube? With regard to the neural crest, we have compared CRABP staining with HNK-1 staining (a marker of migrating neural crest) and found that they do indeed co-localise, but cephalic and trunk crest behave slightly differently. In the cephalic region in tissues such as the frontonasal mass and branchial arches, HNK-1 immunoreactivity is intense at early stages, but it disappears as CRABP immunoreactivity appears. Thus the two staining patterns do not overlap, but are complementary. In the trunk, HNK-1 and CRABP stain the same cell populations at the same time, such as those migrating through the anterior halves of the somites. In the neural tube, CRABP-positive neuroblasts first appear in the rhombencephalon just after the neural folds close and then a particular pattern of immunoreactivity appears within the rhombomeres of the hindbrain. Labelled cells are present in the future spinal cord, the posterior rhombencephalon up to rhombomere 6 and in rhombomere 4 thus producing a single stripe pattern. This pattern is dynamic and gradually changes as anterior rhombomeres begin to label. The similarity of this initial pattern to the arrangement of certain homeobox genes in the mouse stimulated us to examine the expression of the chicken Hox-2.9 gene. We show that at stage 15 the pattern of expression of this gene is closely related to that of CRABP. The relationship between retinoic acid, CRABP and homeobox genes is discussed.
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Zilberman, N. V., M. A. Merrifield, G. S. Carter, D. S. Luther, M. D. Levine, and T. J. Boyd. "Incoherent Nature of M2 Internal Tides at the Hawaiian Ridge." Journal of Physical Oceanography 41, no. 11 (2011): 2021–36. http://dx.doi.org/10.1175/jpo-d-10-05009.1.
Full textAbstract:
Abstract Moored current, temperature, and conductivity measurements are used to study the temporal variability of M2 internal tide generation above the Kaena Ridge, between the Hawaiian islands of Oahu and Kauai. The energy conversion from the barotropic to baroclinic tide measured near the ridge crest varies by a factor of 2 over the 6-month mooring deployment (0.5–1.1 W m−2). The energy flux measured just off the ridge undergoes a similar modulation as the ridge conversion. The energy conversion varies largely because of changes in the phase of the perturbation pressure, suggesting variable work done on remotely generated internal tides. During the mooring deployment, low-frequency current and stratification fluctuations occur on and off the ridge. Model simulations suggest that these variations are due to two mesoscale eddies that passed through the region. The impact of these eddies on low-mode internal tide propagation over the ridge crest is considered. It appears that eddy-related changes in stratification and perhaps cross-ridge current speed contribute to the observed phase variations in perturbation pressure and hence the variable conversion over the ridge.
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Shimada, Kousuke, Toshiaki Tachibana, Kei Fujimoto, Takashi Sasaki, and Masataka Okabe. "Temporal and Spatial Cellular Distribution of Neural Crest Derivatives and Alpha Cells during Islet Development." ACTA HISTOCHEMICA ET CYTOCHEMICA 45, no. 1 (2012): 65–75. http://dx.doi.org/10.1267/ahc.11052.
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