Antiferromagnetic ordering in the Kondo lattice system Yb2_2Fe3_3Si5_5

Compounds belonging to the R$_2$Fe$_3$Si$_5$ series exhibit unusual superconducting and magnetic properties. Although a number of studies have been made on the first reentrant antiferromagnet superconductor Tm$_2$Fe$_3$Si$_5$, the physical properties of Yb$_2$Fe$_3$Si$_5$ are largely unexplored. In this work, we attempt to provide a comprehensive study of bulk properties such as, resistivity, susceptibility and heat-capacity of a well characterized polycrystalline Yb$_2$Fe$_3$Si$_5$. Our measurements indicate that Yb$^{3+}$ moments order antiferromagnetically below 1.7 K. Moreover, the system behaves as a Kondo lattice with large Sommerfeld coefficient ($\gamma$) of 0.5~J/Yb mol K$^{2}$ at 0.3 K, which is well below T$_N$. The absence of superconductivity in Yb$_2$Fe$_3$Si$_5$ down to 0.3 K at ambient pressure is attributed to the presence of the Kondo effect.Comment: 10 pages, 3 figures, tex document. A fuller version has appeared in PRB. Here we have omitted the figures showing the crystal structure and the fitting of the X-ray pattern. Also the table with the lattice parameters obtained from fitting has been remove

Mass-Enhanced Fermi Liquid Ground State in Na1.5_{1.5}Co2_2O4_4

Magnetic, transport, and specific heat measurements have been performed on layered metallic oxide Na$_{1.5}$Co$_2$O$_4$ as a function of temperature $T$. Below a characteristic temperature $T^*$=30$-$40 K, electrical resistivity shows a metallic conductivity with a $T^2$ behavior and magnetic susceptibility deviates from the Curie-Weiss behavior showing a broad peak at $\sim$14 K. The electronic specific heat coefficient $\gamma$ is $\sim$60 mJ/molK$^2$ at 2 K. No evidence for magnetic ordering is found. These behaviors suggest the formation of mass-enhanced Fermi liquid ground state analogous to that in $d$-electron heavy fermion compound LiV$_2$O$_4$.Comment: 4 pages, 4 figures, to be published in Phys. Rev. B 69 (2004

Thermodynamic analysis of the Quantum Critical behavior of Ce-lattice compounds

A systematic analysis of low temperature magnetic phase diagrams of Ce compounds is performed in order to recognize the thermodynamic conditions to be fulfilled by those systems to reach a quantum critical regime and, alternatively, to identify other kinds of low temperature behaviors. Based on specific heat ($C_m$) and entropy ($S_m$) results, three different types of phase diagrams are recognized: i) with the entropy involved into the ordered phase ($S_{MO}$) decreasing proportionally to the ordering temperature ($T_{MO}$), ii) those showing a transference of degrees of freedom from the ordered phase to a non-magnetic component, with their $C_m(T_{MO})$ jump ($\Delta C_m$) vanishing at finite temperature, and iii) those ending in a critical point at finite temperature because their $\Delta C_m$ do not decrease with $T_{MO}$ producing an entropy accumulation at low temperature. Only those systems belonging to the first case, i.e. with $S_{MO}\to 0$ as $T_{MO}\to 0$, can be regarded as candidates for quantum critical behavior. Their magnetic phase boundaries deviate from the classical negative curvature below $T\approx 2.5$\,K, denouncing frequent misleading extrapolations down to T=0. Different characteristic concentrations are recognized and analyzed for Ce-ligand alloyed systems. Particularly, a pre-critical region is identified, where the nature of the magnetic transition undergoes significant modifications, with its $\partial C_m/\partial T$ discontinuity strongly affected by magnetic field and showing an increasing remnant entropy at $T\to 0$. Physical constraints arising from the third law at $T\to 0$ are discussed and recognized from experimental results

Thermodynamics of the dissipative two-state system: a Bethe Ansatz study

The thermodynamics of the dissipative two-state system is calculated exactly for all temperatures and level asymmetries for the case of Ohmic dissipation. We exploit the equivalence of the two-state system to the anisotropic Kondo model and extract the thermodynamics of the former by solving the thermodynamic Bethe Ansatz equations of the latter. The universal scaling functions for the specific heat $C_{\alpha}(T)$ and static dielectric susceptibility $\chi_{\alpha}(T)$ are extracted for all dissipation strengths $0<\alpha<1$ for both symmetric and asymmetric two-state systems. The logarithmic corrections to these quantities at high temperatures are found in the Kondo limit $\alpha\to 1^{-}$, whereas for $\alpha< 1$ we find the expected power law temperature dependences with the powers being functions of the dissipative coupling $\alpha$. The low temperature behaviour is always that of a Fermi liquid.Comment: 24 pages, 32 PS figures. Typos corrected, final versio

FREE ORAL COMMUNICATIONS 2: ALCOHOL AND LIVER—CLINICAL RESEARCHO2.1RAPID DECLINE OF LIVER STIFFNESS WITH ALCOHOL WITHDRAWAL IN HEAVY DRINKERS

Background and aims. Measurement of liver stiffness using real-time elastography appears as a promising tool to evaluate the severity of chronic liver diseases. Previous studies in patients with alcoholic liver disease have suggested that fibrosis was the only histological parameter to influence liver stiffness. To challenge this hypothesis, we have prospectively tested the short-term impact of alcohol withdrawal on liver stiffness value. Methods. All patients hospitalized for alcohol withdrawal in our Liver Unit between September 2008 and December 2010 had a liver stiffness determination (using a FibroScan® device) at entry (D0) and 7 days after alcohol withdrawal (D7). Stiffness values were compared using non-parametric test for paired-values. We compared (i) the 10 measures performed at D0 and at D7 for each patient; (ii) the variation of the median result of all patients (using Wilcoxon test in both cases). Results. A total of 138 patients were included in the study [median alcohol consumption: 150g/day (range: 40-400); hepatitis C: n=22 (15.9%); cirrhosis: n=29 (21.0%)]. From D0 to D7, the liver stiffness decreased significantly in 61 patients (44.2%) and increased significantly in 18 (13.0%). Considering all patients, median liver stiffness value decreased from 7.25 to kPa (P<0.001). The stage of fibrosis indicated by liver stiffness changed in 47 patients between D0 and D7 (decrease in 33 and increase in 14). Conclusion. Liver stiffness decreases significantly in nearly half of alcoholic patients after only 7 days of abstinence. This result strongly suggests that non-fibrotic lesions (such as inflammatory ones) may influence liver stiffness. From a practical point of view, it also shows that variation in alcohol consumption must be taken into account for the interpretation of liver stiffness valu

Long-Term Consequences of COVID-19: A 1-Year Analysis.

Long-lasting symptoms after SARS-CoV-2 infection have been described many times in the literature and are referred to as Long COVID. In this prospective, longitudinal, monocentric, observational study, we collected the health complaints of 474 patients (252 ambulatory and 222 hospitalized) at Lausanne University Hospital 1 year after COVID-19 diagnosis. Using a self-reported health survey, we explored cardiopulmonary, vascular, neurological, and psychological complaints. Our results show that age, Charlson comorbidity index, and smoking habits were associated with hospital admission. Regarding the vascular system, we found that having had thromboembolism before SARS-CoV-2 infection was significantly associated with a higher risk of recurrence of thromboembolism at 1 year. In the neurologic evaluation, the most frequent symptom was fatigue, which was observed in 87.5% of patients, followed by "feeling slowed down", headache, and smell disturbance in 71.5%, 68.5%, and 60.7% of cases, respectively. Finally, our cohort subjects scored higher overall in the STAI, CESD, Maastricht, and PSQI scores (which measure anxiety, depression, fatigue, and sleep, respectively) than the healthy population. Using cluster analysis, we identified two phenotypes of patients prone to developing Long COVID. At baseline, CCS score, prior chronic disease, stroke, and atrial fibrillation were associated with Long COVID. During COVID infection, mechanical ventilation and five neurological complaints were also associated with Long COVID. In conclusion, this study confirms the wide range of symptoms developed after COVID with the involvement of all the major systems. Early identification of risk factors associated with the development of Long COVID could improve patient follow-up; nevertheless, the low specificity of these factors remains a challenge to building a systematic approach

Viral to metazoan marine plankton nucleotide sequences from the Tara Oceans expedition

A unique collection of oceanic samples was gathered by the Tara Oceans expeditions (2009-2013), targeting plankton organisms ranging from viruses to metazoans, and providing rich environmental context measurements. Thanks to recent advances in the field of genomics, extensive sequencing has been performed for a deep genomic analysis of this huge collection of samples. A strategy based on different approaches, such as metabarcoding, metagenomics, single-cell genomics and metatranscriptomics, has been chosen for analysis of size-fractionated plankton communities. Here, we provide detailed procedures applied for genomic data generation, from nucleic acids extraction to sequence production, and we describe registries of genomics datasets available at the European Nucleotide Archive (ENA, www.ebi.ac.uk/ena). The association of these metadata to the experimental procedures applied for their generation will help the scientific community to access these data and facilitate their analysis. This paper complements other efforts to provide a full description of experiments and open science resources generated from the Tara Oceans project, further extending their value for the study of the world's planktonic ecosystems

Antibacterial and antifungal drug concentrations in intra-abdominal abscesses: a prospective clinical study.

Secondary peritonitis with intra-abdominal abscesses (IAA) is difficult to treat because of the supposed low rate of penetration of antimicrobial drugs at the site of infection. However, clinical data about the actual bioavailability of antimicrobial drugs in IAA are scarce. This prospective observational study aimed at assessing the drug penetration in IAA of the antibiotics (piperacillin-tazobactam, carbapenems) and antifungals (fluconazole, echinocandins) that are usually recommended for the treatment of intra-abdominal infections. Patients with IAA who underwent a radiological or surgical drainage procedure were included. Antimicrobial drug concentrations were measured in IAA (C &lt;sub&gt;IAA&lt;/sub&gt; ) and in a simultaneous plasma sample (C &lt;sub&gt;plasma&lt;/sub&gt; ) to assess the C &lt;sub&gt;IAA&lt;/sub&gt; /C &lt;sub&gt;plasma&lt;/sub&gt; ratio. The pharmacodynamic target was defined as a C &lt;sub&gt;IAA&lt;/sub&gt; equal or superior to the clinical breakpoints of susceptibility of the most relevant intra-abdominal pathogens. Clinical outcomes were assessed at hospital discharge. A total of 54 antimicrobial drug measurements were performed in 39 IAA samples originating from 36 patients. Despite important inter-individual variability, piperacillin-tazobactam exhibited the highest C &lt;sub&gt;IAA&lt;/sub&gt; /C &lt;sub&gt;plasma&lt;/sub&gt; ratios (median 2). The rates of target achievement were 75%-80% for piperacillin-tazobactam and meropenem but 0% for imipenem and ertapenem. These results tended to correlate with clinical outcomes (96% success rate versus 73%, respectively, P = 0.07). Among antifungals, fluconazole exhibited higher C &lt;sub&gt;IAA&lt;/sub&gt; /C &lt;sub&gt;plasma&lt;/sub&gt; ratios and rates of target achievement compared to echinocandins. However, no differences in clinical outcomes were observed. These results provide unique information about antimicrobial drug penetration in IAA in real clinical conditions and suggest that piperacillin-tazobactam and meropenem may have better efficacy compared to imipenem or ertapenem