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Aronsson, J. y V. Okhmatovski. "Vectorial Low-Frequency MLFMA for the Combined Field Integral Equation". IEEE Antennas and Wireless Propagation Letters 10 (2011): 532–35. http://dx.doi.org/10.1109/lawp.2011.2157886.
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Corso, P. P., L. Lo Cascio y F. Persico. "Simple vectorial model for the spectrum of a two-level atom in an intense low-frequency field". Physical Review A 58, n.º 2 (1 de agosto de 1998): 1549–58. http://dx.doi.org/10.1103/physreva.58.1549.
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Venter, Gert J., I. Hermanides, D. Majatladi, S. Boikanyo y I. Wright. "Interactions vecteurs-virus : diversité des sérotypes et des souches de la peste équine africaine, et populations géographiques". Revue d’élevage et de médecine vétérinaire des pays tropicaux 62, n.º 2-4 (1 de febrero de 2009): 107. http://dx.doi.org/10.19182/remvt.10023.
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The most abundant Culicoides species in an area is not inevitably the most competent vector species for a specific virus. Oral susceptibility, as an indicator of vector competence, is a measure of the portion of vectors taking a blood meal from an infected host that actually becomes infective. Cumulative laboratory oral susceptibility results from South Africa indicate a multivector potential for bluetongue virus (BTV) as well as for African horse sickness virus (AHSV). Considering the unique biology of potential vector competent Culicoides species one can appreciate the complex epidemiology of these diseases. The oral susceptibly of C. imicola, a proven vector of AHSV and BTV, was relatively low for most of the viral isolates and even appeared to be refractory to infection with some of the isolates used. This relatively low oral susceptibility may partly explain the low field infection prevalence of AHSV and BTV recorded in field collected midges. In South Africa, the relatively low oral susceptibility as determined for some of the isolates is easily compensated for by the high abundance of C. imicola. Differences found in the virus recovery rates of various AHSV serotypes/isolates from the various Culicoides species and even different populations of the same species emphasize the fact that, although oral susceptibility tests provide important information about a specific vector population, it provides no predictability about the behaviour of other populations with different strains of virus. Differences found in the oral susceptibility of C. imicola and C. bolitinos for isolates of the same serotypes of AHSV suggest coadaptation between orbiviruses and vectors present in a given locality. Real-time monitoring of vector competence might be difficult as it would require assessing local Culicoides populations using variants of orbiviruses currently in circulation. It needs to be emphasized that laboratory demonstration of oral susceptibility is not the only necessary step to implement a competent vector. It is, however, an indication of the ability of a vector to support virus replication and one of the critical components of vectorial capacity. Vector capacity is the relative measure of a vector population to transmit a virus to a vertebrate population. In addition to vector competence, vectorial capacity depends on the biting rate, host selection, vector survivorship, and the extrinsic incubation period of the virus.
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Hiptmair, Ralf y Carolina Urzúa-Torres. "Preconditioning the EFIE on screens". Mathematical Models and Methods in Applied Sciences 30, n.º 09 (agosto de 2020): 1705–26. http://dx.doi.org/10.1142/s0218202520500347.
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We consider the electric field integral equation (EFIE) modeling the scattering of time-harmonic electromagnetic waves at a perfectly conducting screen. When discretizing the EFIE by means of low-order Galerkin boundary methods (BEM), one obtains linear systems that are ill-conditioned on fine meshes and for low wave numbers [Formula: see text]. This makes iterative solvers perform poorly and entails the use of preconditioning. In order to construct optimal preconditioners for the EFIE on screens, the authors recently derived compact equivalent inverses of the EFIE operator on simple Lipschitz screens in [R. Hiptmair and C. Urzúa-Torres, Compact equivalent inverse of the electric field integral operator on screens, Integral Equations Operator Theory 92 (2020) 9]. This paper elaborates how to use this result to build an optimal operator preconditioner for the EFIE on screens that can be discretized in a stable fashion. Furthermore, the stability of the preconditioner relies only on the stability of the discrete [Formula: see text] duality pairing for scalar functions, instead of the vectorial one. Therefore, this novel approach not only offers [Formula: see text]-independent and [Formula: see text]-robust condition numbers, but it is also easier to implement and accommodates non-uniform meshes without additional computational effort.
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Nattoh, Godfrey, Joel L. Bargul, Gabriel Magoma, Lilian Mbaisi, Hellen Butungi, Enock Mararo, Evan Teal y Jeremy Keith Herren. "The fungus Leptosphaerulina persists in Anopheles gambiae and induces melanization". PLOS ONE 16, n.º 2 (22 de febrero de 2021): e0246452. http://dx.doi.org/10.1371/journal.pone.0246452.
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Anopheles mosquitoes are colonized by diverse microorganisms that may impact on host biology and vectorial capacity. Eukaryotic symbionts such as fungi have been isolated from Anopheles, but whether they are stably associated with mosquitoes and transmitted transstadially across mosquito life stages or to subsequent generations remains largely unexplored. Here, we show that a Leptosphaerulina sp. fungus isolated from the midgut of An. gambiae can be stably associated with An. gambiae host and that it imposes low fitness cost when re-introduced through co-feeding. This fungus is transstadially transmitted across An. gambiae developmental stages and to their progeny. It is present in field-caught larvae and adult mosquitoes at moderate levels across geographical regions. We observed that Leptosphaerulina sp. induces a distinctive melanotic phenotype across the developmental stages of mosquito. As a eukaryotic symbiont that is stably associated with An. gambiae Leptosphaerulina sp. can be explored for paratransgenesis.
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Rana, Sohel, Harish Subbaraman, Austin Fleming y Nirmala Kandadai. "Numerical Analysis of Radiation Effects on Fiber Optic Sensors". Sensors 21, n.º 12 (15 de junio de 2021): 4111. http://dx.doi.org/10.3390/s21124111.
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Optical fiber sensors (OFS) are a potential candidate for monitoring physical parameters in nuclear environments. However, under an irradiation field the optical response of the OFS is modified via three primary mechanisms: (i) radiation-induced attenuation (RIA), (ii) radiation-induced emission (RIE), and (iii) radiation-induced compaction (RIC). For resonance-based sensors, RIC plays a significant role in modifying their performance characteristics. In this paper, we numerically investigate independently the effects of RIC and RIA on three types of OFS widely considered for radiation environments: fiber Bragg grating (FBG), long-period grating (LPG), and Fabry-Perot (F-P) sensors. In our RIC modeling, experimentally calculated refractive index (RI) changes due to low-dose radiation are extrapolated using a power law to calculate density changes at high doses. The changes in RI and length are subsequently calculated using the Lorentz–Lorenz relation and an established empirical equation, respectively. The effects of both the change in the RI and length contraction on OFS are modeled for both low and high doses using FIMMWAVE, a commercially available vectorial mode solver. An in-depth understanding of how radiation affects OFS may reveal various potential OFS applications in several types of radiation environments, such as nuclear reactors or in space.
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Jones, Robert T., Thomas H. Ant, Mary M. Cameron y James G. Logan. "Novel control strategies for mosquito-borne diseases". Philosophical Transactions of the Royal Society B: Biological Sciences 376, n.º 1818 (28 de diciembre de 2020): 20190802. http://dx.doi.org/10.1098/rstb.2019.0802.
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Mosquito-borne diseases are an increasing global health challenge, threatening over 40% of the world's population. Despite major advances in malaria control since 2000, recent progress has stalled. Additionally, the risk of Aedes -borne arboviruses is rapidly growing, with the unprecedented spread of dengue and chikungunya viruses, outbreaks of yellow fever and the 2015 epidemic of Zika virus in Latin America. To counteract this growing problem, diverse and innovative mosquito control technologies are currently under development. Conceptually, these span an impressive spectrum of approaches, from invasive transgene cassettes with the potential to crash mosquito populations or reduce the vectorial capacity of a population, to low-cost alterations in housing design that restrict mosquito entry. This themed issue will present articles providing insight into the breadth of mosquito control research, while demonstrating the requirement for an interdisciplinary approach. The issue will highlight mosquito control technologies at varying stages of development and includes both opinion pieces and research articles with laboratory and field-based data on control strategy development. This article is part of the theme issue ‘Novel control strategies for mosquito-borne diseases'.
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Szabó, Attila-Károly, József Kiss, János Bálint, Szidónia Kőszeghi, Hugh D. Loxdale y Adalbert Balog. "Low and high input agricultural fields have different effects on pest aphid abundance via different invasive alien weed species". NeoBiota 43 (13 de marzo de 2019): 27–45. http://dx.doi.org/10.3897/neobiota.43.31553.
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We conducted field surveys to detect the population density of the most important invasive weed species and their associated virus vectoring aphids in crops grown under high input field (HIF) vs low-input field (LIF) conditions, with and without fertilizers and pesticides. The most frequent invasive weed species were Stenactisannua, Erigeroncanadensis and Solidagocanadensis. These species were hosts predominantly for the aphids Brachycaudushelichrysi and Aulacorthumsolani in both management systems. The 13% higher coverage of S.annua under LIF conditions resulted in a 30% higher B.helichrysi abundance and ~85% higher A.solani abundance compared with HIF conditions. Host plant quality was assessed by measuring peroxidase enzyme activity. There was a significantly increased POD activity at 10 μmol min−1 mg protein−1 unit in S.annua under LIF conditions, suggesting a higher stress by aphids under this management regime. The high colonization intensity of B.helichrysi on maize, potato and alfalfa crops were detected from both S.annua and E.canadensis. We conclude that new and faster methods need to be used to prevent colonization of such virus vectoring aphids and their host plants, even under low input regimes.
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Gillgrist, R. D., D. J. Forliti y P. J. Strykowski. "On the Mechanisms Affecting Fluidic Vectoring Using Suction". Journal of Fluids Engineering 129, n.º 1 (2 de junio de 2006): 91–99. http://dx.doi.org/10.1115/1.2375125.
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Suction was applied asymmetrically to the exhaust of a rectangular subsonic jet creating a pressure field capable of vectoring the primary flow at angles up to 15deg. The suction simultaneously creates low pressures near the jet exhaust and conditions capable of drawing a secondary flow along the jet shear layer in the direction opposite to the primary jet. This countercurrent shear layer is affected both by the magnitude of the suction source as well as the proximity of an adjacent surface onto which the pressure forces act to achieve vectoring. This confined countercurrent flow gives rise to elevated turbulence levels in the jet shear layer as well as considerable increases in the gradients of the turbulent stresses. The turbulent stresses are responsible for producing a pressure field conducive for vectoring the jet at considerably reduced levels of secondary mass flow than would be possible in their absence.
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Raman, G., S. Packiarajan, G. Papadopoulos, C. Weissman y S. Raghu. "Jet thrust vectoring using a miniature fluidic oscillator". Aeronautical Journal 109, n.º 1093 (marzo de 2005): 129–38. http://dx.doi.org/10.1017/s0001924000000634.
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Abstract This paper presents a new approach to vectoring jet thrust using a miniature fluidic actuator that provided spatially distributed mass addition. The fluidic actuators used had no moving parts and produced oscillatory flow with a square wave form at frequencies up to 1·6kHz. A subsonic jet with an exit diameter of 3·81cm was controlled using single and dual fluidic actuators, each with an equivalent circular diameter of 1·06mm. The fluidic nozzle was operated at pressures between 20·68 and 165·47kPa. The objectives of the present work included documentation of the actuation characteristics of fluidic devices, assessment of the effectiveness of fluidic devices for jet thrust vectoring, and evaluation of mass flow requirements for vectoring under various conditions. Measurements were made in the flow field using a pitot probe for the vectored and unvectored cases. Some acoustic measurements were made using microphones in the near-field and for selected cases particle image velocimetry (PIV) measurements were made. Thrust vectoring was obtained in low speed jets by momentum effects with fluidic device mass flow rates of only 2 × 10–4kg/sec (0·6% of main jet mass flow per fluidic oscillator). Although a single fluidic device produced vectoring of the primary jet, the dual fluidic device configuration (with two fluidic devices on either side of the jet exit) produced mass flux enhancement of 28% with no vectoring. Our results indicate that fluidic actuators have the potential for use in thrust vectoring, flow mixing and industrial flow deflection applications.
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Xue, Fei, Gu Yunsong, Yuchao Wang y Han Qin. "Research on control effectiveness of fluidic thrust vectoring". Science Progress 104, n.º 1 (enero de 2021): 003685042199813. http://dx.doi.org/10.1177/0036850421998137.
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In view of the control effects of fluidic thrust vector technology for low-speed aircraft at high altitude/low density and low altitude/high density are studied. The S-A model of FLUENT software is used to simulate the flow field inside and outside the nozzle with variable control surface parameters, and the relationship between the area of control surface and the deflection effect of main flow at different altitudes is obtained. It is found that the fluidic thrust vectoring nozzle can effectively control the internal flow in the ground state and the high altitude/low density state. and the mainstream deflection angle can be continuously adjusted. The maximum deflection angle of the flow in the ground state is 21.86°, and the maximum deviation angle of the 20 km high altitude/low density state is 18.80°. The deflecting of the inner flow of the nozzle is beneficial to provide more lateral force and lateral torque for the aircraft. The high altitude/low density state is taken as an example. When the internal flow deflects 18.80°, the lateral force is 0.32 times the main thrust. For aircraft with high altitude and low density, sufficient lateral and lateral torque can make the flying aircraft more flexible, which can make up the shortcomings of the conventional rudder failure and even replace the conventional rudder surface.
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Doria, R. y I. Soares. "Spin-Valued Four Bosons Electrodynamics". JOURNAL OF ADVANCES IN PHYSICS 19 (31 de mayo de 2021): 93–133. http://dx.doi.org/10.24297/jap.v19i.9030.
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Electromagnetism is based on electric charge and spin. The study here corresponds to understand on spin effects at a vectorial electrodynamics. Its scenario is a non-linear abelian electromagnetism where the electric charge is transmitted through a four bosons quadruplet, constituted by the usual photon, massive photon and charged massive photons. These four bosons intermediate the charge exchange ΔQ = 0, ±1.The spin is introduced at first principles. A spintronics Lagrangian for four vector fields is performed. Considering that spin is a space-time physical entity derived from Lorentz Group, these vector fields are associated to Lorentz Group, as Lie algebra valued. Similarly to non-abelian gauge theories where Aμ≡ Aμ,ata, one introduces the relationship Aμ≡ Aμ,κλΣκλ where (Σκλ)αβ is the Lorentz Group generator. Thus, based on three fundamentals which are light invariance, electric charge conservation law and vector fields Lie algebra valued through Lorentz Group generators, one derives a spin-valued four vectorial electrodynamics. It is given by the fields quadruplet Aμ1 ≡ {Aμ, Uμ, Vμ±} where Aμ means the usual photon, Uμ a massive photon and Vμ± massive charged photons. Two novelties appear. The first one is that, new terms are developed into usual four bosons electromagnetism. They contribute to Lagrangian, equations of motion, Noether theorem. The second one is that the equations of motion derive a renormalizable spin coupling with the electric and magnetic fields.There is a spin-1 electrodynamics to be investigated. A neutral electromagnetism is mandatory to be analyzed. Something beyond dipole, quadrupole and so on. Understand the role of spin in the electrical and magnetic properties of particles. A spin vectorial expression S--> is obtained. It adds EM interactions not depending on electric charge and with spin interactions through electric dipole and magnetic moments.
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ACCIOLY, ANTONIO y ESLLEY SCATENA. "LIMITS ON THE COUPLING CONSTANT OF HIGHER-DERIVATIVE ELECTROMAGNETISM". Modern Physics Letters A 25, n.º 04 (10 de febrero de 2010): 269–76. http://dx.doi.org/10.1142/s0217732310031610.
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We investigate a higher-derivative version of QED constructed by adding to the Maxwell's Lagrangian a term containing second-order derivatives of the electromagnetic potentials. The resulting Lagrangian, besides being gauge and Lorentz invariant, gives origin to local field equations that are linear in the field quantities. Two bounds on the coupling constant of this higher-order model are estimated: one of them is found using the measurements obtained on a lab experiment whose principal aim was to test the Coulomb's inverse square law, the other involves the computation of the anomalous magnetic moment of the electron in the framework of the aforementioned system. As a by-product of the calculations on the quantum limit, a bound on the Lee–Wick heavy photon mass of the same order of magnitude as the masses of the vectorial bosons found in nature, is obtained as well.
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Wu, Kexin y Heuy Dong Kim. "Numerical study on the shock vector control in a rectangular supersonic nozzle". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, n.º 13 (8 de marzo de 2019): 4943–65. http://dx.doi.org/10.1177/0954410019834133.
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In recent decades, the fluidic thrust vector control technique is one of the core strategies to redirect various aerospace vehicles, such as modern launch rockets, supersonic aircraft, and guided missiles. The fundamental theory of the shock vector control is that the gas is injected into the supersonic part of a conventional convergent–divergent nozzle from the transverse to cause interactions between the shock waves and boundary layers. Then, the deflection of the primary jet can be easily realized by the induced oblique shock waves. It was evident that the shock vector control is a very simple, low weight, low cost, and quick vectoring response technique to gain high thrust vectoring performance. In the present work, computational fluid dynamics studies were performed at different control parameters in a three-dimensional rectangular supersonic nozzle with the slot injector. For the validation of the numerical methodology, computational results were compared with experimental data referred to the NASA Langley Research Center. The static pressure distributions along the upper and lower nozzle surfaces in the symmetry plane were matched with the test data excellently. Numerical simulations were based on the well-assessed shear stress transport k–ω turbulence model. Second-order accuracy was selected to reveal more details of the flow-field as much as possible. Lots of factors were investigated, such as the momentum flux ratio, length-to-width ratio, injection location, and injection angle. The performance variations for different affecting factors were illustrated and some constructive conclusions were obtained to provide the reference for further investigations in fluidic thrust vector control field.
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Li, Weipeng y Lipo Wang. "Geometrical structure analysis of a zero-pressure-gradient turbulent boundary layer". Journal of Fluid Mechanics 846 (4 de mayo de 2018): 318–40. http://dx.doi.org/10.1017/jfm.2018.249.
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The present work focuses on the geometrical features of a zero-pressure-gradient turbulent boundary layer based on vectorline segment analysis. In a turbulent vector field, tracing from any non-singular point, along either the vector or the inverse direction, one will reach a local extremum of the vector magnitude. The vectorline between the two local extrema is defined as the vectorline segment corresponding to the given spatial point. Specifically the vectorline segment can be the streamline segment for the velocity vector case, or the vorticity line segment for the vorticity vector case. Such a quantitatively defined and space-filling vectorline segment structure reflects the natural vectorial topology. Because of inhomogeneity in the wall-normal direction, vectorline segments corresponding to the grid points at specified wall-normal distances are sampled for statistics. For streamline segments, the probability density function (p.d.f.) of the normalized segment length in different flow regions matches a model solution, and for vorticity line segments such a p.d.f. in the log-law region and beyond matches the same model solution, which indicates some universality of different flow regions and different vector field structures. Typically the joint p.d.f. of the characteristic parameters of streamline segments presents clear asymmetry, which is closely related to the skewness of the velocity derivative. Moreover, the orientation statistics of vectorline segments, characterized by the coordinate difference between the segment starting point and ending point, have been provided to quantify the flow anisotropy.
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Silva, João Paulo, Christophe De Wagter y Guido de Croon. "Quadrotor Thrust Vectoring Control with Time and Jerk Optimal Trajectory Planning in Constant Wind Fields". Unmanned Systems 06, n.º 01 (enero de 2018): 15–37. http://dx.doi.org/10.1142/s2301385018500024.
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This paper proposes a trajectory planning and control strategy to optimally visit a given set of waypoints in the presence of wind. First, aerodynamic properties of quadrotors which affect trajectory planning and tracking performance are investigated. Blade flapping, induced and parasitic drag are derived and an extended method to identify all coefficients from flight test data is developed. Then, a three-step approach is suggested to optimize the trajectory. These steps reduce the size of the optimization problem and thereby increase computational efficiency while still guaranteeing near optimal results. The trajectories are optimized for minimal aerodynamic drag and minimal jerk. The derived smooth trajectory generation is compared with traditional trajectory planning consisting of discrete point to point tracking followed by low-pass filtering. The new trajectories yield a clear reduction in maximal needed thrust and in Euler angle aggressiveness. A thrust vectoring controller is designed, which exploits the a priori trajectory information and identified aerodynamic properties. Its performance is compared to a standard PID controller and results show a reduction in tracking delay and an increase in thrust and attitude angle margins, which overall enable faster flight.
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von Rütte, Mirjam, Niklaus Peyer, Benedikt Schmidt, Nina Keller y Céline Geiser. "Assessing whether disinfectants against the fungus Batrachochytrium dendrobatidis have negative effects on tadpoles and zooplankton". Amphibia-Reptilia 30, n.º 3 (2009): 313–19. http://dx.doi.org/10.1163/156853809788795245.
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AbstractChytridiomycosis is an emerging disease of amphibians that has led to global population declines and possible extinctions. Vectoring of the pathogen, Batrachochytrium dendrobatidis (Bd) by anthropogenic means is thought to be important in its spread. To limit further increase in the distribution of Bd, field biologists and amateur naturalists ought to disinfect their boots and materials. However, imprudent use of potentially harmful disinfectants may have unwanted negative side effects on amphibians. We used a factorial experiment to test whether commonly used disinfectants (bleach and Virkon S) affect tadpole performance and zooplankton abundance. At the high dose of bleach, all tadpoles and zooplankton died. Tadpole performance and zooplankton abundance in the low dose of bleach and Virkon S treatments were undistinguishable from the control. Therefore, when bleach is used as a disinfectant, it must not get in contact with amphibians. Virkon S appears to be a disinfectant that can be used against Bd with no detectable negative effects on tadpoles and zooplankton.
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Díaz-Franulic, Ignacio, Vivian González-Pérez, Hans Moldenhauer, Nieves Navarro-Quezada y David Naranjo. "Gating-induced large aqueous volumetric remodeling and aspartate tolerance in the voltage sensor domain of Shaker K+ channels". Proceedings of the National Academy of Sciences 115, n.º 32 (23 de julio de 2018): 8203–8. http://dx.doi.org/10.1073/pnas.1806578115.
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Neurons encode electrical signals with critically tuned voltage-gated ion channels and enzymes. Dedicated voltage sensor domains (VSDs) in these membrane proteins activate coordinately with an unresolved structural change. Such change conveys the transmembrane translocation of four positively charged arginine side chains, the voltage-sensing residues (VSRs; R1–R4). Countercharges and lipid phosphohead groups likely stabilize these VSRs within the low-dielectric core of the protein. However, the role of hydration, a sign-independent charge stabilizer, remains unclear. We replaced all VSRs and their neighboring residues with negatively charged aspartates in a voltage-gated potassium channel. The ensuing mild functional effects indicate that hydration is also important in VSR stabilization. The voltage dependency of the VSR aspartate variants approached the expected arithmetic summation of charges at VSR positions, as if negative and positive side chains faced similar pathways. In contrast, aspartates introduced between R2 and R3 did not affect voltage dependence as if the side chains moved outside the electric field or together with it, undergoing a large displacement and volumetric remodeling. Accordingly, VSR performed osmotic work at both internal and external aqueous interfaces. Individual VSR contributions to volumetric works approached arithmetical additivity but were largely dissimilar. While R1 and R4 displaced small volumes, R2 and R3 volumetric works were massive and vectorially opposed, favoring large aqueous remodeling during VSD activation. These diverse volumetric works are, at least for R2 and R3, not compatible with VSR translocation across a unique stationary charge transfer center. Instead, VSRs may follow separated pathways across a fluctuating low-dielectric septum.
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Amadio, Guilherme, Ananya, John Apostolakis, Marilena Bandieramonte, Shiba Behera, Abhijit Bhattacharyya, René Brun et al. "Recent progress with the top to bottom approach to vectorization in GeantV". EPJ Web of Conferences 214 (2019): 02007. http://dx.doi.org/10.1051/epjconf/201921402007.
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SIMD acceleration can potentially boost by factors the application throughput. Achieving efficient SIMD vectorization for scalar code with complex data flow and branching logic, goes however way beyond breaking some loop dependencies and relying on the compiler. Since the refactoring effort scales with the number of lines of code, it is important to understand what kind of performance gains can be expected in such complex cases. We started to investigate a couple of years ago a top to bottom vectorization approach to particle transport simulation. Percolating vector data to algorithms was mandatory since not all the components can internally vectorize. Vectorizing low-level algorithms is certainly necessary, but not sufficient to achieve relevant SIMD gains. In addition, the overheads for maintaining the concurrent vector data flow and copy data have to be minimized. In the context of a vectorization R&D for simulation we developed a framework to allow different categories of scalar and vectorized components to co-exist, dealing with data flow management and real-time heuristic optimizations. The paper describes our approach on coordinating SIMD vectorization at framework level, making a detailed quantitative analysis of the SIMD gain versus overheads, with a breakdown by components in terms of geometry, physics and magnetic field propagation. We also present the more general context of this R&D work and goals for 2018.
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Michailides, Themis J. y David P. Morgan. "Spread of Endosepsis in Calimyrna Fig Orchards". Phytopathology® 88, n.º 7 (julio de 1998): 637–47. http://dx.doi.org/10.1094/phyto.1998.88.7.637.
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Pollination of the edible fig (Ficus carica cv. Calimyrna) is mediated by a small symbiotic wasp, Blastophaga psenes, that inhabits the syconium cavity of the spring crop of fig pollinator trees (caprifigs). These fig wasps also carry propagules, mainly of Fusarium verticillioides (formerly F. moniliforme) and other Fusarium spp., which cause endosepsis, from pollinator figs to the edible Calimyrna figs in California. Spread of endosepsis was studied in one experimental and up to four commercial Calimyrna fig orchards from 1989 through 1995. The incidence of endosepsis in fruit collected from the tree canopy at either <2.0 m (low) or >2.0 m (high) height, from the north and south of the tree canopy, and from the outer (direct sunlight) and inner (shaded) canopy were similar. More wasps were captured in fig trees located 3.5 to 10 m east or west of the source than in trees 48 to 63 m from the source. In addition, significantly more wasps entered the syconia of trees closest (9 to 12.7 m) to the source than the syconia of the second or third trees (18 to 38.2 m) from the source. Endosepsis decreased with distance from the source, decreasing faster to the south than in other directions from the source. In addition, the disease-vectoring wasps decreased with increased distance from the source, which also described the disease spread from the contamination source for most directions, with a sharper decline south of the source. A 3-year study in three commercial Calimyrna orchards showed there is no secondary spread of fig endosepsis in the field. Although endosepsis can complete as many cycles (three to four) as its vector in fig pollinator trees, in Calimyrna figs it is considered a monocyclic disease. Because fig wasp pollinators prefer to stay close to the contamination source when receptive Calimyrna figs are available in close proximity, only disease sources (caprifigs trees) found among Calimyrna trees or at a distance less than 50 m from the borders of Calimyrna orchards affect endosepsis incidence in commercial orchards.
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Kwon, Hongwook, Ho Heon Kim, Jaeil An, Jae-Ho Lee y Yu Rang Park. "Lifelog Data-Based Prediction Model of Digital Health Care App Customer Churn: Retrospective Observational Study". Journal of Medical Internet Research 23, n.º 1 (6 de enero de 2021): e22184. http://dx.doi.org/10.2196/22184.
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Background Customer churn is the rate at which customers stop doing business with an entity. In the field of digital health care, user churn prediction is important not only in terms of company revenue but also for improving the health of users. Churn prediction has been previously studied, but most studies applied time-invariant model structures and used structured data. However, additional unstructured data have become available; therefore, it has become essential to process daily time-series log data for churn predictions. Objective We aimed to apply a recurrent neural network structure to accept time-series patterns using lifelog data and text message data to predict the churn of digital health care users. Methods This study was based on the use data of a digital health care app that provides interactive messages with human coaches regarding food, exercise, and weight logs. Among the users in Korea who enrolled between January 1, 2017 and January 1, 2019, we defined churn users according to the following criteria: users who received a refund before the paid program ended and users who received a refund 7 days after the trial period. We used long short-term memory with a masking layer to receive sequence data with different lengths. We also performed topic modeling to vectorize text messages. To interpret the contributions of each variable to model predictions, we used integrated gradients, which is an attribution method. Results A total of 1868 eligible users were included in this study. The final performance of churn prediction was an F1 score of 0.89; that score decreased by 0.12 when the data of the final week were excluded (F1 score 0.77). Additionally, when text data were included, the mean predicted performance increased by approximately 0.085 at every time point. Steps per day had the largest contribution (0.1085). Among the topic variables, poor habits (eg, drinking alcohol, overeating, and late-night eating) showed the largest contribution (0.0875). Conclusions The model with a recurrent neural network architecture that used log data and message data demonstrated high performance for churn classification. Additionally, the analysis of the contribution of the variables is expected to help identify signs of user churn in advance and improve the adherence in digital health care.
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Sala, Filip. "Beam splitting in chiral nematic liquid crystals". Photonics Letters of Poland 10, n.º 4 (31 de diciembre de 2018): 109. http://dx.doi.org/10.4302/plp.v10i4.867.
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By lunching the beam into the chiral nematic liquid crystals it is possible to achieve a non-diffractive beam similar to a soliton. This effect is caused by the molecular reorientation i.e. nonlinear response of the material forming the areas of higher refractive index. Diffraction is suppressed by the focusing effect. For appropriate launching conditions it is also possible to achieve a beam which splits into two or more separate beams. Such phenomenon is discussed in this article and analyzed theoretical. To model this effect Fully Vectorial Beam Propagation Method coupled with the Frank-Oseen elastic theory is used. Simulations are performed for various input beam powers, widths, polarization angles and launching positions. Full Text: PDF ReferencesG. Assanto and M. A. Karpierz, "Nematicons: self-localised beams in nematic liquid crystals", Liq. Cryst. 36, 1161–1172 (2009) CrossRef G. Assanto, Nematicons: Spatial Optical Solitons in Nematic Liquid Crystals, John Wiley & Sons Inc. Hoboken, New Jersey (2013) DirectLink A. Piccardi, A. Alberucci, U. Bortolozzo, S. Residori, and G. Assanto, "Soliton gating and switching in liquid crystal light valve", Appl. Phys. Lett. 96, 071104 (2010). CrossRef D. Melo, I. Fernandes, F. Moraes, S. Fumeron, and E. Pereira, "Thermal diode made by nematic liquid crystal", Phys. Lett. A 380, 3121 – 3127 (2016). CrossRef U. Laudyn, M. Kwaśny, F. A. Sala, M. A. Karpierz, N. F. Smyth, G. Assanto, "Curved optical solitons subject to transverse acceleration in reorientational soft matter", Sci. Rep. 7, 12385 (2017) CrossRef M. Kwaśny, U. A. Laudyn, F. A. Sala, A. Alberucci, M. A. Karpierz, G. Assanto, "Self-guided beams in low-birefringence nematic liquid crystals", Phys. Rev. A 86, 013824 (2012) CrossRef F. A. Sala, M. M. Sala-Tefelska, "Optical steering of mutual capacitance in a nematic liquid crystal cell", J. Opt. Soc. Am. B. 35, 133-139 (2018) CrossRef U. A. Laudyn, A. Piccardi, M. Kwasny, M. A. Karpierz, G. Assanto, "Thermo-optic soliton routing in nematic liquid crystals", Opt. Lett. 43, 2296-2299 (2018) CrossRef F. A. Sala, M. M. Sala-Tefelska, M. J. Bujok, J. "Influence of temperature diffusion on molecular reorientation in nematic liquid crystals", Nonlinear Opt. Phys. Mater. 27, 1850011 (2018) CrossRef I-C Khoo Liquid crystals John Wiley & Sons, Inc (2007) DirectLink P. G. de Gennes, J. Prost, The Physics of Liquid Crystals, Clarendon Press (1995) DirectLink U. A. Laudyn, P. S. Jung, M. A. Karpierz, G. Assanto, "Quasi two-dimensional astigmatic solitons in soft chiral metastructures", Sci. Rep. 6, 22923 (2016) CrossRef J. Beeckman, A. Madani, P. J. M. Vanbrabant, P. Henneaux, S-P. Gorza, M. Haelterman, "Switching and intrinsic position bistability of soliton beams in chiral nematic liquid crystals", Phys. Rev. A 83, 033832 (2011) CrossRef A. Madani, J. Beeckman, K. Neyts, "An experimental observation of a spatial optical soliton beam and self splitting of beam into two soliton beams in chiral nematic liquid crystal", Opt. Commun. 298–299, 222-226, (2013) CrossRef G. D. Ziogos, E. E. Kriezis, "Modeling light propagation in liquid crystal devices with a 3-D full-vector finite-element beam propagation method", Opt. Quant. Electron 40, 10 (2008) CrossRef F. A. Sala, M. A. Karpierz, "Chiral and nonchiral nematic liquid-crystal reorientation induced by inhomogeneous electric fields", J. Opt. Soc. Am. B 29, 1465-1472 (2012) CrossRef F. A. Sala, M. A. Karpierz, "Modeling of molecular reorientation and beam propagation in chiral and non-chiral nematic liquid crystals", Opt. Express 20, 13923-13938 (2012) CrossRef F. A. Sala, "Design of false color palettes for grayscale reproduction", Displays, 46, 9-15 (2017) CrossRef
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Fogliano, Francesco, Benjamin Besga, Antoine Reigue, Laure Mercier de Lépinay, Philip Heringlake, Clement Gouriou, Eric Eyraud, Wolfgang Wernsdorfer, Benjamin Pigeau y Olivier Arcizet. "Ultrasensitive nano-optomechanical force sensor operated at dilution temperatures". Nature Communications 12, n.º 1 (5 de julio de 2021). http://dx.doi.org/10.1038/s41467-021-24318-y.
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AbstractCooling down nanomechanical force probes is a generic strategy to enhance their sensitivities through the concomitant reduction of their thermal noise and mechanical damping rates. However, heat conduction becomes less efficient at low temperatures, which renders difficult to ensure and verify their proper thermalization. Here we implement optomechanical readout techniques operating in the photon counting regime to probe the dynamics of suspended silicon carbide nanowires in a dilution refrigerator. Readout of their vibrations is realized with sub-picowatt optical powers, in a situation where less than one photon is collected per oscillation period. We demonstrate their thermalization down to 32 ± 2 mK, reaching very large sensitivities for scanning probe force sensors, 40 zN Hz−1/2, with a sensitivity to lateral force field gradients in the fN m−1 range. This opens the road toward explorations of the mechanical and thermal conduction properties of nanoresonators at minimal excitation level, and to nanomechanical vectorial imaging of faint forces at dilution temperatures.
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Łebek, Maciej y Pawel Jakubczyk. "Thermodynamic Casimir forces in strongly anisotropic systems within the $N\to \infty$ class". SciPost Physics Core 4, n.º 2 (7 de junio de 2021). http://dx.doi.org/10.21468/scipostphyscore.4.2.016.
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We analyze the thermodynamic Casimir effect in strongly anisotropic systems from the vectorial N\to\inftyN→∞ class in a slab geometry. Employing the imperfect (mean-field) Bose gas as a representative example, we demonstrate the key role of spatial dimensionality dd in determining the character of the effective fluctuation-mediated interaction between the confining walls. For a particular, physically conceivable choice of anisotropic dispersion relation and periodic boundary conditions, we show that the Casimir force at criticality as well as within the low-temperature phase is repulsive for dimensionality d\in (\frac{5}{2},4)\cup (6,8)\cup (10,12)\cup\dotsd∈(52,4)∪(6,8)∪(10,12)∪… and attractive for d\in (4,6)\cup (8,10)\cup \dotsd∈(4,6)∪(8,10)∪…. We argue, that for d\in\{4,6,8\dots\}d∈{4,6,8…} the Casimir interaction entirely vanishes in the scaling limit. We discuss implications of our results for systems characterized by 1/N>01/N>0 and possible realizations in the contexts of optical lattice systems and quantum phase transitions.
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Shen, Li, Kwee-Yan Teh, Penghui Ge, Fengnian Zhao y David LS Hung. "Temporal evolution analysis of in-cylinder flow by means of proper orthogonal decomposition". International Journal of Engine Research, 28 de mayo de 2020, 146808742091724. http://dx.doi.org/10.1177/1468087420917246.
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In-cylinder flow fields and their temporal evolution have strong effect on the combustion dynamics of internal combustion engines. Proper orthogonal decomposition is a statistical tool to analyze these flow fields by decomposing them into flow patterns (known as proper orthogonal decomposition modes) and corresponding coefficients with their contribution to the ensemble flow kinetic energy successively maximized. However, neither of the two prevailing proper orthogonal decomposition approaches satisfactorily describes the temporal behavior of the flow fields. The phase-dependent proper orthogonal decomposition approach is limited to analyzing spatial flow structures at a certain engine phase. The phase-invariant proper orthogonal decomposition approach attempts to account for both spatial and temporal variations, but at the expense of diminished statistical and physical significance. In this article, we seek to understand the temporal behavior of tumble flow fields by analyzing the evolution of low-order phase-dependent proper orthogonal decomposition modes over multiple crank angles. The concept of relevance index is first generalized to enable comparison between two vectorial fields of different sizes. This metric is then used to quantify the directional similarities between the two lowest proper orthogonal decomposition modes obtained at sequential crank angles. The mode shapes are observed to evolve gradually and naturally over most crank angles, but change significantly at certain crank angles during intake. The results indicate that each of the low-order modes features strong velocity fluctuations in different regions of the tumble plane, and different numbers of modes are needed to represent the dominant features of tumble flow at different engine phases. Based on this understanding, we propose to use the partial sum of those proper orthogonal decomposition modes and their coefficients to form a low-order approximation model of the in-cylinder tumble flow, in order to reduce flow field complexity and noise while retaining its major spatial and temporal features.
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Shragai, Talya, Laura Harrington, Catalina Alfonso-Parra y Frank Avila. "Oviposition site attraction of Aedes albopictus to sites with conspecific and heterospecific larvae during an ongoing invasion in Medellín, Colombia". Parasites & Vectors 12, n.º 1 (18 de septiembre de 2019). http://dx.doi.org/10.1186/s13071-019-3710-6.
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Abstract Background Aedes aegypti and Aedes albopictus are two globally invasive vectors with similar ecological niches. Encounters between them can result in either competitive exclusion or stable co-existence, but it is unclear what drives these variable outcomes. Larval competition in favor of Ae. albopictus is a main hypothesis for the competitive exclusion of Ae. aegypti observed in some regions. However, the role of oviposition preference in determining the degree of competitive larval interactions in the field is not well understood. In this study, we used a combination of mark-release-recapture methods with ovitraps in the open-field and a semi-field cage to test whether gravid Ae. albopictus seek oviposition sites in response to the presence, species, and density of either conspecific or heterospecific Ae. aegypti larvae in the aquatic habitat. We conducted our study in Medellín, Colombia, where Ae. aegypti is a long-term resident and Ae. albopictus is a recent invader. Results In the open-field and semi-field cage experiments, gravid Ae. albopictus showed strong preference for ovitraps with larvae over those without. They consistently preferred ovitraps with higher density of conspecific (Ae. albopictus) larvae and low density of heterospecific (Ae. aegypti) larvae over traps with no larvae or high density of heterospecific (Ae. aegypti) larvae. In the semi-field cage experiment, traps with low density of Ae. albopictus were not preferred more or less than any other trap, but in the open-field experiment they were preferred over traps without larvae. Conclusions We demonstrate, through open-field and semi-field cage experiments, that Ae. albopictus are more attracted to oviposition sites with larvae and that the combination of species and density of larvae influence attraction. This demonstrated preference could increase interspecific larval competition as Ae. albopictus actively seek containers with conspecific and heterospecific larvae. Any resulting competition with Ae. aegypti may favor one species over the other and alter the distribution or abundance of both. Because these species vary in vectorial capacity and insecticide resistance, effects of interspecific competition could ultimately impact arbovirus transmission rates and the success of vector control efforts.
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Latif, A. A., M. A. Bakheit, Amna E. E. Mohamed y E. Zweygarth. "High infection rates of the tick Hyalomma anatolicum anatolicum with Trypanosoma theileri". Onderstepoort J Vet Res 71, n.º 4 (8 de noviembre de 2004). http://dx.doi.org/10.4102/ojvr.v71i4.228.
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A crossbred calf (3 months old) obtained from a farm where regular control of ticks was practised and found to be free of blood parasites was inoculated with 20 ml pooled blood collected from four field cattle which had very low Trypanosoma theileri parasitaemias (one parasite per 70 µl blood as determined by the haematocrit centrifugation technique). Trypanosoma theileri was present in the blood 6 days after injection and a peak parasitaemia of 42 parasites per 70 µl blood was recorded by day 12. Hyalomma anatolicum anatolicum nymphs were applied on the ears of the calf on day 8 and they dropped engorged by days 13 and 14. The resulting adult ticks were examined for the presence of T. theileri by severing a leg and making a smear of the clear haemolymph which exuded from the wound. The smear was fixed in methanol and stained with Giemsa stain. The infection rate with T. theileri in the ticks was 43.3 % (26 out of 60). The intensity of infection was very high and various developmental stages of the flagellates were observed (epimastigotes, sphaeromastigotes, trypomastigotes and other intermediate stages). The haemolymph from 12 ticks was also collected in tissue culture medium and the trypanosomes survived for 25 weeks before eventually dying. The results demonstrated unequivocally the high vectorial capacity of the tick H. a. anatolicum for T. theileri.
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Coëtmellec, S., D. Lebrun, M. Brunel y A. J. E. M. Janssen. "Assessment about Luneberg integrals and application to digital in-line holography". Journal of the European Optical Society-Rapid Publications 17, n.º 1 (30 de junio de 2021). http://dx.doi.org/10.1186/s41476-021-00154-x.
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AbstractIn this publication, the Luneberg integrals are revisited and the conditions of the using of such integrals have been recalled. Additivity law of Luneberg’s integrals and the link with the Frenel kernel for the propagation are discussed. By means of the definition of the Luneberg’s integrals, the propagation of a vectorial electromagnetic field (Hertz potentials) is developed and a new approach of the computation have been proposed based on Zernike polynomials. With this new approach simulations of holograms is illustrated in the case of the digital in-line holography with an opaque disk.
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Boyer, Matthew David Hank y Lynn S. Adler. "Variation in pollinator potential to carry a blueberry fungal pathogen and assessment of transfer efficiency in two managed bee species". Journal of Pollination Ecology 25 (5 de junio de 2019). http://dx.doi.org/10.26786/1920-7603(2019)529.
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Plant diseases are ubiquitous in agricultural systems and are major sources of economic loss. Vaccinium corymbosum, or highbush blueberry, is an economically important crop affected by an insect-vectored, fungal pathogen, Monilinia vaccinii-corymbosi, or mummy berry disease. Highbush blueberry yield is maximized through outcrossed pollination; however, the pathogen is vectored by pollinators. We used field collections and molecular techniques to identify floral visitors to highbush blueberry and quantify levels of pathogen spores carried by each visiting species. We also conducted a cage trial using single flower visits to determine differences in vectoring efficiency between two managed pollinators, Apis mellifera and Bombus impatiens. We found that bees, flies, and wasps were all common visitors, and that all bee species and several fly and wasp species carried the pathogen. Of the bee species, A. mellifera most often tested positive for the pathogen, while Dolichovespula maculata (Bald-faced Hornet) tested positive most among wasps and Mallota posticata among flies. Considering only individuals that tested positive, mummyberry levels per individual were highest in D. maculata and Andrena bees, and relatively low in flies. In cage trials, we found no differences between A. mellifera and B. impatiens in pathogen load or transfer efficiency, suggesting that these managed species are equally capable of vectoring mummyberry during a single visit to a blighted stem and then a flower. This research demonstrates the variety of floral visitors that carry mummyberry and that two common commercial pollinator species have similar potential to vector mummyberry to blueberry flowers during a single visit.
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Matougui, Brahim, Abdelbasset Boukelia, Hacene Belhadef, Clovis Galiez y Mohamed Batouche. "NLP-MeTaxa: A Natural Language Processing approach for Metagenomic Taxonomic Binning based on deep learning". Current Bioinformatics 16 (21 de junio de 2021). http://dx.doi.org/10.2174/1574893616666210621101150.
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Background: Metagenomics is the study of genomic content in mass from an environment of interest such as the human gut or soil. Taxonomy is one of the most important fields of metagenomics, which is the science of defining and naming groups of microbial organisms that share the same characteristics. The problem of taxonomy classification is the identification and quantification of microbial species or higher-level taxa sampled by high throughput sequencing. Objective: Although many methods exist to deal with the taxonomic classification problem, assignment to low taxonomic ranks remains an important challenge for binning methods as is scalability to Gb-sized datasets generated with deep sequencing techniques. Methods: In this paper, we introduce NLP-MeTaxa, a novel composition-based method for taxonomic binning, which relies on the use of words embeddings and deep learning architecture. The new proposed approach is word-based, where the metagenomic DNA fragments are processed as a set of overlapping words by using the word2vec model to vectorize them in order to feed the deep learning model. NLP-MeTaxa output is visualized as NCBI taxonomy tree, this representation helps to show the connection between the predicted taxonomic identifiers. NLP-MeTaxa was trained on large-scale data from the NCBI RefSeq, more than 14,000 complete microbial genomes. The NLP-MeTaxa code is available at the website: https://github.com/padriba/NLP_MeTaxa/ Results: We evaluated NLP-MeTaxa with a real and simulated metagenomic dataset and compared our results to other tools' results. The experimental results have shown that our method outperforms the other methods especially for the classification of low-ranking taxonomic class such as species and genus. Conclusion: In summary, our new method might provide novel insight for understanding the microbial community through the identification of the organisms it might contain.
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Ballmann, Mónika Z., Svjetlana Raus, Ruben Engelhart, Győző L. Kaján, Abdelaziz Beqqali, Patrick WF Hadoke, Chantal van der Zalm et al. "Human AdV-20-42-42, a promising novel adenoviral vector for gene therapy and vaccine product development". Journal of Virology, septiembre de 2021. http://dx.doi.org/10.1128/jvi.00387-21.
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Pre-existing immune responses towards adenoviral vector limit the use of a vector based on particular serotypes and its clinical applicability for gene therapy and/or vaccination. Therefore, there is a significant interest to vectorize novel adenoviral types that have low seroprevalence in the human population. Here, we describe the discovery and vectorization of a chimeric human adenovirus, which we call HAdV-20-42-42. Full genome sequencing revealed that this virus is closely related to human serotype 42, except for the penton-base which is derived from serotype 20. The HAdV-20-42-42 vector could be propagated stably to high titers on existing E1-complementing packaging cell lines. Receptor binding studies revealed that the vector utilized both CAR and CD46 as receptors for cell entry. Furthermore, the HAdV-20-42-42 vector was potent in transducing human and murine cardiovascular cells and tissues, irrespective of the presence of blood coagulation factor X. In vivo characterizations demonstrate that when delivered intravenously (i.v.) in mice, HAdV-20-42-42 mainly targeted the lungs, liver and spleen and triggered robust inflammatory immune response. Finally, we demonstrate that potent T-cell responses against vector-delivered antigens could be induced upon intramuscular vaccination in mice. In summary, from the data obtained we conclude that HAdV-20-42-42 provides a valuable addition to the portfolio of adenoviral vectors available to develop efficacious products in the fields of gene therapy and vaccination. IMPORTANCE Adenoviral vectors are currently under investigation for a broad range of therapeutic indications in diverse fields, such as oncology and gene therapy, as well as for vaccination both for human and veterinary use. A wealth of data shows that pre-existing immune responses may limit the use of a vector. Particularly in the current climate of global pandemic, there is a need to expand the toolbox with novel adenoviral vectors for vaccine development. Our data demonstrates that we have successfully vectorized a novel adenovirus type candidate with low seroprevalence. The cell transduction data and antigen-specific immune responses induced in vivo demonstrate that this vector is highly promising for the development of gene therapy and vaccine products.