Electrical resistivity ofYb(Rh1-xCox)2Si2 single crystals at low temperatures

We report low-temperature measurements of the electrical resistivity of Yb(Rh1-xCox)2Si2 single crystals with 0 <= x <= 0.12. The isoelectronic substitution of Co on the Rh site leads to a decrease of the unit cell volume which stabilizes the antiferromagnetism. Consequently, the antiferromagnetic transition temperature increases upon Co substitution. For x = 0.07 Co content a subsequent low-temperature transition is observed in agreement with susceptibility measurements and results on YbRh2Si2 under hydrostatic pressure. Above the Neel transition the resistivity follows a non-Fermi liquid behavior similar to that of YbRh2Si2.Comment: 4 pages, submitted to SCES0

Tick fauna of cattle in northeastern part of Serbia (Banat)

The present study was conducted in 30 cattle herd from the territory of Banat (Vojvodina) in the period of March to October 2019, during the grazing season was to established tick fauna in that arae. Ticks were collected from cattle and from pastures where they were grazed. The tick species and sex/gender were identified by morphometric characteristics. Relative abundance analysis revealed that the I. ricinus was absolutely dominant species found in 71.22%, followed by Haemaphysalis punctata (18.22%), Dermacentor marginatus (11.72%), Rhipicephalus sanguineus (3.22%) and Rhipicephalus bursa (2.01%). On the pasture, however, the most common species was H. punctata, followed by I. ricinus, D. marginatus, R. sanguineus and R.bursa. Out of the total number of ticks collected, 53.65% were females and 46.35% were males. The sex ratio showed a higher number of females in four species (Ixodes ricinus, Haemaphysalis punctata, Rhipicephalus sanguineus and Dermacentor marginatus), while higher number of males were detected in Rhipicephalus bursa. The population dynamics of recorded tick species showed two annual maxima, in spring (April-May) and in autumn (September-October). The considerable interchange between spring and autumn tick populations can be attributed mainly to environmental conditions

Divergence of the Grueneisen Ratio at Quantum Critical Points in Heavy Fermion Metals

We present low-temperature volume thermal expansion, $\beta$, and specific heat, $C$, measurements on high-quality single crystals of CeNi2Ge2 and YbRh2(Si$_{0.95}$Ge$_{0.05}$)$_2$ which are located very near to quantum critical points. For both systems, $\beta$ shows a more singular temperature dependence than $C$, and thus the Grueneisen ratio ${\Gamma \propto \beta/C}$ diverges as T --> 0. For CeNi2Ge2, our results are in accordance with the spin-density wave (SDW) scenario for three-dimensional critical spin-fluctuations. By contrast, the observed singularity in YbRh2$(Si$_{0.95}$Ge$_{0.05}$)$_2$ cannot be explained by the itinerant SDW theory but is qualitatively consistent with a locally quantum critical picture.Comment: 11 pages, 4 figure

Break up of heavy fermions at an antiferromagnetic instability

We present results of high-resolution, low-temperature measurements of the Hall coefficient, thermopower, and specific heat on stoichiometric YbRh2Si2. They support earlier conclusions of an electronic (Kondo-breakdown) quantum critical point concurring with a field induced antiferromagnetic one. We also discuss the detachment of the two instabilities under chemical pressure. Volume compression/expansion (via substituting Rh by Co/Ir) results in a stabilization/weakening of magnetic order. Moderate Ir substitution leads to a non-Fermi-liquid phase, in which the magnetic moments are neither ordered nor screened by the Kondo effect. The so-derived zero-temperature global phase diagram promises future studies to explore the nature of the Kondo breakdown quantum critical point without any interfering magnetism.Comment: minor changes, accepted for publication in JPS

Nod2 Mediates Susceptibility to Yersinia pseudotuberculosis in Mice

Nucleotide oligomerisation domain 2 (NOD2) is a component of the innate immunity known to be involved in the homeostasis of Peyer patches (PPs) in mice. However, little is known about its role during gut infection in vivo. Yersinia pseudotuberculosis is an enteropathogen causing gastroenteritis, adenolymphitis and septicaemia which is able to invade its host through PPs. We investigated the role of Nod2 during Y. pseudotuberculosis infection. Death was delayed in Nod2 deleted and Crohn's disease associated Nod2 mutated mice orogastrically inoculated with Y. pseudotuberculosis. In PPs, the local immune response was characterized by a higher KC level and a more intense infiltration by neutrophils and macrophages. The apoptotic and bacterial cell counts were decreased. Finally, Nod2 deleted mice had a lower systemic bacterial dissemination and less damage of the haematopoeitic organs. This resistance phenotype was lost in case of intraperitoneal infection. We concluded that Nod2 contributes to the susceptibility to Y. pseudotuberculosis in mice

Frequency of gastrointestinal and pulmonary helminth infections in wild deer from western Romania

A survey was carried out to assess the prevalence and the intensity of helminth infections in the roe deer (Capreolus capreolus L.), red deer (Cervus elaphus L.) and fallow deer (Dama dama L.) from 16 hunting areas in western Romania. Overall, 122 deer shot during the hunting season 2013\u20132015 were examined. Haemonchus contortus, Nematodirus filicollis, Oesophagostomum venulosum and Dictyocalus spp. were found in all the deer species. Trichuris spp. and Dicrocoelium dendriticum were found in the roe deer and red deer and Moniezia expansa in roe deer, only. Overall, the prevalences ( 50%). No > 2 or 3 helminth species were found in the abomasum, small and large intestine. Lung helminthes in the roe deer and follow deer accounted for 57.1% and 71.4%, respectively. The only specie with a prevalence > 50% was in the red deer. D. dendriticum was found in the liver of roe deer and fallow deer