1,029 research outputs found
Electronic, magnetic and transport properties of Fe intercalated 2H-TaS studied by means of the KKR-CPA method
The electronic, magnetic and transport properties of Fe intercalated
2H-TaS have been investigated by means of the Korringa-Kohn-Rostoker (KKR)
method. The non-stoichiometry and disorder in the system has been accounted for
using the Coherent Potential Approximation (CPA) alloy theory. A pronounced
influence of disorder on the spin magnetic moment has been found for the
ferro-magnetically ordered material. The same applies for the spin-orbit
induced orbital magnetic moment and magneto-crystalline anisotropy energy. The
temperature-dependence of the resistivity of disordered 2H-FeTaS
investigated on the basis of the Kubo-St\v{r}eda formalism in combination with
the alloy analogy model has been found in very satisfying agreement with
experimental data. This also holds for the temperature dependent anomalous Hall
resistivity . The role of thermally induced lattice
vibrations and spin fluctuations for the transport properties is discussed in
detail
Electronic structure and magnetic properties of CrSb and FeSb investigated via ab-initio calculations
The electronic structure and magnetic properties of CrSb have been
investigated by ab-initio calculations with an emphasis on the role of the
magnetic structure for the ground state. The influence of correlation effects
has been investigated by performing fixed spin moment (FSM) calculations
showing their important role for the electronic and magnetic properties. The
details of the electronic structure of CrSb are analyzed by a comparison
with those of FeSb. The results obtained contribute in particular to the
understanding of the temperature dependence of transport and magnetic behavior
observed experimentally
Effects of blood parasite infections on spatiotemporal migration patterns and activity budgets in a long-distance migratory passerine
How blood parasite infections influence the migration of hosts remains a lively debated issue as past studies found negative, positive or no response to infections. This particularly applies to small birds, for which monitoring of detailed migration behaviour ovea whole annual cycle has been technically unachievable so far. Here, we investigate how bird migration is influenced by parasite infections. To this end, we tracked great reed warblers (Acrocephalus arundinaceus) with multi-sensor loggers, characterized general migration patterns as well as detailed flight bout durations, resting times and flight heights and related these to the genus and intensity of their avian haemosporidian infections. We found migration distances to be shorter and the onset of autumn migration to be delayed with increasing intensity of blood parasite infection, in particular for birds with Plasmodium and mixed-genus infections. Additionally, the durations of migratory flight bout were prolonged for infected compared to uninfected birds. But since severely infected birds and particularly birds with mixed genus infections had shorter resting times, initial delays seemed to be compensated for and the timing in other periods of the annual cycle was not compromised by infection. Overall, our multi-sensor logger approach revealed that avian blood parasites have mostly subtle effects on migratory performance and that effects can occur in specific periods of the year only
A rare study from the wintering grounds provides insight into the costs of malaria infection for migratory birds
Malaria parasites can have strong effects on the population dynamics and evolution of migratory bird species. In many species, parasite transmission occurs on the wintering grounds, but studies to determine the consequences of infection have taken place during the breeding season, when malaria parasites circulate at chronic levels. We examined the predictors of malarial infections for great reed warblers during the northern winter in Africa, where active parasite transmission is thought to occur and naïve individuals experience acute infections. Counter to expectations, we found that winter infection intensities were lower than those encountered on the breeding grounds. One potential explanation is that reduced immune function during breeding allows parasites to persist at higher chronic intensities. We found no relationships between the incidence or intensity of infection on condition (as measured by scaled mass index, plasma metabolites, and feather corticosterone), spring migration departure dates, or home range sizes. We also tested a prediction of the Hamilton–Zuk hypothesis and found that male ornament (song) quality was unrelated to parasitic infection status. Overall, our results provide the first evidence that long‐distance migrants captured on their wintering grounds are in the chronic stage of infection, and suggest that winter studies may fare no better than breeding studies at determining the costs of acute malarial infection for great reed warblers.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1111/jav.0087
- …