Protocols for characterizing quantum transport through nano-structures

In this work, we have analyzed the exact closed-form solutions for transport quantities through a mesoscopic region which may be characterized by a polynomial functional of resonant transmission functions. These are then utilized to develop considerably improved protocols for parameters relevant for quantum transport through molecular junctions and quantum dots. The protocols are shown to be experimentally feasible and should yield the parameters at much higher resolution than the previously proposed ones.Comment: 5 pages, 2 figure

Spectral changes in layered ff-electron systems induced by Kondo hole substitution in the boundary-layer

We investigate the effect of disorder on the dynamical spectrum of layered $f$-electron systems. With random dilution of $f$-sites in a single Kondo insulating layer, we explore the range and extent to which Kondo hole incoherence can penetrate into adjacent layers. We consider three cases of neighboring layers: band insulator, Kondo insulator and simple metal. The disorder-induced spectral weight transfer, used here for quantification of the proximity effect, decays algebraically with distance from the boundary layer. Further, we show that the spectral weight transfer is highly dependent on the frequency range considered as well as the presence of interactions in the clean adjacent layers. The changes in the low frequency spectrum are very similar when the adjacent layers are either metallic or Kondo insulating, and hence are independent of interactions. In stark contrast, a distinct picture emerges for the spectral weight transfers across large energy scales. The spectral weight transfer over all energy scales is much higher when the adjacent layers are non-interacting as compared to when they are strongly interacting Kondo insulators. Thus, over all scales, interactions screen the disorder effects significantly. We discuss the possibility of a crossover from non-Fermi liquid to Fermi liquid behavior upon increasing the ratio of clean to disordered layers in particle-hole asymmetric systems.Comment: 14 pages, 9 figure

Cambios temporales en la diversidad de los cangrejos braquiuros a lo largo de un hábitat heterogéneo del manglar indio de Sundarban

The present study investigates the effect of different habitat attributes on brachyuran crab diversity in two different study sites in the Sundarban mangrove, India. The two sites differ in the level of anthropogenic intrusion and in the age of the mangrove forest. Seasonal changes in the environment and in brachyuran faunal abundance were recorded for three years. Species composition varied between the two habitats irrespective of season. The habitat heterogeneity and the recorded crab community was analysed by several univariate and multivariate statistical techniques. The newly replanted mangrove site showed lesser diversity than the natural one. Ocypodid crabs, mainly Uca rosea, dominated both study sites, whereas Uca triangularis was totally absent from the replanted site. Canonical correspondence analysis showed that the total acidity, total alkalinity, pH content of water, total dissolved solids, inorganic phosphate content of water, soil specific gravity, soil density and the physical constructions of the habitat play a crucial role in moderating the crab community structure. This study reveals that brachyuran crab diversity can be used as a potential indicator of the alterations of mangrove habitats.El presente estudio investiga el efecto de las diferentes características de hábitat sobre la diversidad de los cangrejos braquiuros en dos lugares diferentes del manglar Sundarban, India. Los dos sitios difieren en el nivel de intrusión antropogénica, así como en la edad del bosque de manglar. Se registraron cambios estacionales en el medio y en la abundancia de la fauna de braquiuros durante tres años. A pesar de las diferencias estacionales, la composición de especies difiere en los dos hábitats. Se analizó la heterogeneidad del hábitat y la comunidad de cangrejos mediante técnicas estadísticas univariantes y multivariantes. La zona de manglares replantada recientemente mostró menor diversidad que la zona natural. Los cangrejos ocipódidos, principalmente Uca rosea, dominaron en ambas zonas de estudio, mientras que Uca triangularis estuvo totalmente ausente en la zona replantada. El análisis de Correspondencia Canónica (CCA) mostró que la acidez total, la alcalinidad total, el contenido de pH del agua, los sólidos totales disueltos (TDS), el contenido de fosfato inorgánico del agua, el peso específico del suelo, la densidad del suelo, junto con las construcciones físicas del hábitat desempeñan un papel fundamental en la estructura de la comunidad de cangrejos. Este estudio revela que la diversidad de los cangrejos braquiuros puede ser utilizada como un potencial indicador de las alteraciones de los hábitats de manglares

Dynamics of Oxygen-Plankton Model with Variable Zooplankton Search Rate in Deterministic and Fluctuating Environments

It is estimated by scientists that 50–80% of the oxygen production on the planet comes from the oceans due to the photosynthetic activity of phytoplankton. Some of this production is consumed by both phytoplankton and zooplankton for cellular respiration. In this article, we have analyzed the dynamics of the oxygen-plankton model with a modified Holling type II functional response, based on the premise that zooplankton has a variable search rate, rather than constant, which is ecologically meaningful. The positivity and uniform boundedness of the studied system prove that the model is well-behaved. The feasibility conditions and stability criteria of each equilibrium point are discussed. Next, the occurrence of local bifurcations are exhibited taking each of the vital system parameters as a bifurcation parameter. Numerical simulations are illustrated to verify the analytical outcomes. Our findings show that (i) the system dynamics change abruptly for a low oxygen production rate, resulting in depletion of oxygen and plankton extinction; (ii) the proposed system has oscillatory behavior in an intermediate range of oxygen production rates; (iii) it always has a stable coexistence steady state for a high oxygen production rate, which is dissimilar to the outcome of the model of a coupled oxygen-plankton dynamics where zooplankton consumes phytoplankton with classical Holling type II functional response. Lastly, the effect of environmental stochasticity is studied numerically, corresponding to our proposed system.This research was funded by the Spanish Government and European Commission for its support through grant RTI2018-094336-B-I00 (MCIU/AEI/FEDER, UE) and to the Basque Government for its support through grant IT1207-1