Environmental variables structuringLabeo species (Pisces, Cyprinidae) in Malebo Pool, Congo River

This study examined the effect of ten environmental variables on the distribution of five species of the Cyprinid fish (Labeo lineatus, L. nasus, L. macrostomus, L. sorex and L. weeksii) in Malebo Pool, Congo River. A total of 3468 individuals of Labeo spp. were collected in 7 sites. Three species namely Labeo lineatus, L. weeksii and L. sorex represented 94% of the total number of Labeo caught in 7 sites. A significant correlation between species distribution and environmental variables was found using the Canonical Correspondence Analysis. Water depth and current speed, dissolved oxygen concentration and substrate types were the main environmental variables influencing the distribution of Labeo species in Malebo Pool and these species are accordingly divided in two groups. Three species: Labeo sorex, L. nasus and L. macrostomus prefer deep, rocky sites with fast current and high dissolved oxygen concentration. These species are thus considered as rheophilic. Two species: Labeo lineatus and L. weeksii are considered limnophilic as they are usually found in shallow sites with slow current and lower dissolved oxygen concentration. In this last group, L. weeksii was found in sandy sites while L. lineatus preferred mud

Study of EMIC wave excitation using direct ion measurements

With data from Van Allen Probes, we investigate electromagnetic ion cyclotron (EMIC) wave excitation using simultaneously observed ion distributions. Strong He band waves occurred while the spacecraft was moving through an enhanced density region. We extract from helium, oxygen, proton, and electron mass spectrometer measurement the velocity distributions of warm heavy ions as well as anisotropic energetic protons that drive wave growth through the ion cyclotron instability. Fitting the measured ion fluxes to multiple sinm-type distribution functions, we find that the observed ions make up about 15% of the total ions, but about 85% of them are still missing. By making legitimate estimates of the unseen cold (below ∼2 eV) ion composition from cutoff frequencies suggested by the observed wave spectrum, a series of linear instability analyses and hybrid simulations are carried out. The simulated waves generally vary as predicted by linear theory. They are more sensitive to the cold O+ concentration than the cold He+ concentration. Increasing the cold O+ concentration weakens the He band waves but enhances the O band waves. Finally, the exact cold ion composition is suggested to be in a range when the simulated wave spectrum best matches the observed one

Measurement of one-particle correlations and momentum distributions for trapped 1D gases

van Hove's theory of scattering of probe particles by a macroscopic target is generalized so as to relate the differential cross section for atomic ejection via stimulated Raman transitions to one-particle momentum-time correlations and momentum distributions of 1D trapped gases. This method is well suited to probing the longitudinal momentum distributions of 1D gases in situ, and examples are given for bosonic and fermionic atoms.Comment: 4 pages, 2 .eps figure

Distributions of particulate Heme b in the Atlantic and Southern Oceans-Implications for electron transport in phytoplankton

Concentrations of heme b, the iron-containing component of b-type hemoproteins, ranged from  500). High chl a:heme b ratios resulted from relative decreases in heme b, suggesting proteins such as cytochrome b6f, the core complex of photosystem II, and eukaryotic nitrate reductase were depleted relative to proteins containing chlorophyll such as the eukaryotic light-harvesting antenna. Relative variations in heme b, particulate organic carbon, and chl a can thus be indicative of a physiological response of the phytoplankton community to the prevailing growth conditions, within the context of large-scale changes in phytoplankton community composition

Ergonomic Analysis of Veterinary Surgical Tasks

Studies have observed injuries and musculoskeletal discomforts among surgeons in human medicine. It is likely that veterinary surgeons endure similar discomfort; however, limited work has been done in this domain. Therefore, this research aims to identify occupational risk factors affecting the upper extremities of leading and assisting surgeons in orthopedic and soft tissue small animal surgeries. As a result, we aim to reduce surgeon injuries by assessing the surgical environment in veterinary care. To collect objective metrics, inertial measurement units (IMUs), heart rate monitors, and Electromyography (EMG) sensors are used. In addition, surveys are used to evaluate perceived pain before and after surgery and the workload of the task. In total, 5 participants were studied over 26 surgeries. Postoperatively, neck discomfort was most commonly recorded. Neck discomfort was reported in two-thirds of the cases by of the orthopedic surgeons and over one-third of the soft tissue surgeries. Average perceived workload was reported higher in orthopedic surgeries compared to soft tissue surgeries. When measuring the deltoid and trapezius muscle activities, orthopedic surgeons exerted about 21% of their maximum muscle force across the two muscle groups and soft tissue surgeons exerted 12%. These results provide insight to surgeons\u27 perceived workload and physical efforts associated with performing surgery, and further applications of this work may translate to modifications to surgical environments or additional surgeon education to reduce physical strains

First inventory of macroinvertebrates of River Niger in Niamey as bioindicators of urban and industrial pollution

L’approche biologique, basée sur la distribution des peuplements de macro-invertébrés le long du fleuve Niger à Niamey, permet une bonne caractérisation biologique des stations d’échantillonnage. L’échantillonnage des macro-invertébrés à chacune de ces stations est effectué grâce au filet troubleau, aux substrats artificiels et à la jacinthe d’eau. Cette approche montre l’évolution de la richesse et de la diversité taxonomique le long des stations. Ainsi, la richesse et la diversité taxonomique diminuent en passant de l’amont à l’aval des points de rejets. Les stations de référence et les stations en aval éloigné des rejets présentent une diversité plus satisfaisante comparativement aux stations en aval immédiat des rejets. Il ressort de l’ordination des taxons que les stations en amont et en aval éloigné des rejets sont les moins polluées et abritent des taxons qui sont sensibles à la pollution comme Thraulus sp., Elassoneuria sp., Afronurus sp., Centroptiloides sp., Adenophlebia sp., Dipseudopsis sp.et Neoperla sp. Les stations en aval immédiat de la brasserie du Niger et de l’abattoir paraissent être les plus polluées avec la présence des taxons comme Chironomus gr. plumosus, Syrphidae et Culicidae. Le changement dans la composition des assemblages taxonomiques, l’indice de diversité de Shannon-Weaver et l’abondance des taxons sont des indicateurs d’une modification de la qualité de l’eau et de l’habitat en passant de l’amont à l’aval des points de rejets de la ville de Niamey

Non-local string theories on AdS_3 times S^3 and stable non-supersymmetric backgrounds

We exhibit a simple class of exactly marginal "double-trace" deformations of two dimensional CFTs which have AdS_3 duals, in which the deformation is given by a product of left and right-moving U(1) currents. In this special case the deformation on AdS_3 is generated by a local boundary term in three dimensions, which changes the physics also in the bulk via bulk-boundary propagators. However, the deformation is non-local in six dimensions and on the string worldsheet, like generic non-local string theories (NLSTs). Due to the simplicity of the deformation we can explicitly make computations in the non-local string theory and compare them to CFT computations, and we obtain precise agreement. We discuss the effect of the deformation on closed strings and on D-branes. The examples we analyze include a supersymmetry-breaking but exactly marginal "double-trace" deformation, which is dual to a string theory in which no destabilizing tadpoles are generated for moduli nonperturbatively in all couplings, despite the absence of supersymmetry. We explain how this cancellation works on the gravity side in string perturbation theory, and also non-perturbatively at leading order in the deformation parameter. We also discuss possible flat space limits of our construction.Comment: 40 pages, 6 figures, harvma

Classical information deficit and monotonicity on local operations

We investigate classical information deficit: a candidate for measure of classical correlations emerging from thermodynamical approach initiated in [Phys. Rev. Lett 89, 180402]. It is defined as a difference between amount of information that can be concentrated by use of LOCC and the information contained in subsystems. We show nonintuitive fact, that one way version of this quantity can increase under local operation, hence it does not possess property required for a good measure of classical correlations. Recently it was shown by Igor Devetak, that regularised version of this quantity is monotonic under LO. In this context, our result implies that regularization plays a role of "monotoniser".Comment: 6 pages, revte

The approach to thermalization in the classical phi^4 theory in 1+1 dimensions: energy cascades and universal scaling

We study the dynamics of thermalization and the approach to equilibrium in the classical phi^4 theory in 1+1 spacetime dimensions. At thermal equilibrium we exploit the equivalence between the classical canonical averages and transfer matrix quantum traces of the anharmonic oscillator to obtain exact results for the temperature dependence of several observables, which provide a set of criteria for thermalization. We find that the Hartree approximation is remarkably accurate in equilibrium. The non-equilibrium dynamics is studied by numerically solving the equations of motion in light-cone coordinates for a broad range of initial conditions and energy densities.The time evolution is described by several stages with a cascade of energy towards the ultraviolet. After a transient stage, the spatio-temporal gradient terms become larger than the nonlinear term and a stage of universal cascade emerges.This cascade starts at a time scale t_0 independent of the initial conditions (except for very low energy density). Here the power spectra feature universal scaling behavior and the front of the cascade k(t) grows as a power law k(t) sim t^alpha with alpha lesssim 0.25. The wake behind the cascade is described as a state of Local Thermodynamic Equilibrium (LTE) with all correlations being determined by the equilibrium functional form with an effective time dependent temperatureTeff(t) which slowly decreases as sim t^{-alpha}.Two well separated time scales emerge while Teff(t) varies slowly, the wavectors in the wake with k < k(t) attain LTE on much shorter time scales.This universal scaling stage ends when the front of the cascade reaches the cutoff at a time t_1 sim a^{-1/alpha}. Virialization starts to set much earlier than LTE. We find that strict thermalization is achieved only for an infinite time scale.Comment: relevance for quantum field theory discussed providing validity criteria. To appear in Phys. Rev.