Thermoelectric power quantum oscillations in the ferromagnet UGe2_2

We present thermoelectric power and resistivity measurements in the ferromagnet UGe$_2$ as a function of temperature and magnetic field. At low temperature, huge quantum oscillations are observed in the thermoelectric power as a function of the magnetic field applied along the $a$ axis. The frequencies of the extreme orbits are determined and an analysis of the cyclotron masses is performed following different theoretical approaches for quantum oscillations detected in the thermoelectric power. They are compared to those obtained by Shubnikov-de Haas experiments on the same crystal and previous de Haas-van Alphen experiments. The agreement of the different probes confirms thermoelectric power as an excellent probe to extract simultaneously both microscopic and macroscopic information on the Fermi-surface properties. Band-structure calculations of UGe$_2$ in the ferromagnetic state are compared to the experiment.Comment: 10 figures, 12 pages, accepted for publication in Phys. Rev.

Fermi surface instabilities in CeRh2Si2 at high magnetic field and pressure

We present thermoelectric power (TEP) studies under pressure and high magnetic field in the antiferromagnet CeRh2Si2 at low temperature. Under magnetic field, large quantum oscillations are observed in the TEP, S(H), in the antiferromagnetic phase. They suddenly disappear when entering in the polarized paramagnetic (PPM) state at Hc pointing out an important reconstruction of the Fermi surface (FS). Under pressure, S/T increases strongly of at low temperature near the critical pressure Pc, where the AF order is suppressed, implying the interplay of a FS change and low energy excitations driven by spin and valence fluctuations. The difference between the TEP signal in the PPM state above Hc and in the paramagnetic state (PM) above Pc can be explained by different FS. Band structure calculations at P = 0 stress that in the AF phase the 4f contribution at the Fermi level (EF) is weak while it is the main contribution in the PM domain. By analogy to previous work on CeRu2Si2, in the PPM phase of CeRh2Si2 the 4f contribution at EF will drop.Comment: 10 pages, 13 figure

Interaction-driven quantum phase transition of a single magnetic impurity in Fe(Se,Te)

Understanding the interplay between individual magnetic impurities and superconductivity is crucial for bottom-up construction of novel phases of matter. For decades, the description by Yu, Shiba and Rusinov (YSR) of single spins in a superconductor and its extension to include quantum effects has proven highly successful: the pair-breaking potential of the spin generates sub-gap electron- and hole excitations that are energetically equidistant from zero. By tuning the energy of the sub-gap states through zero, the impurity screening by the superconductor makes the ground state gain or lose an electron, signalling a parity breaking quantum phase transition. Here we show that in multi-orbital impurities, correlations between the in-gap states can conversely lead to a quantum phase transition where more than one electron simultaneously leave the impurity without significant effect of the screening by the superconductor, while the parity may remain unchanged. This finding implies that the YSR treatment is not always valid, and that intra-atomic interactions, particularly Hund's coupling that favours high spin configurations, are an essential ingredient for understanding the sub-gap states. The interaction-driven quantum phase transition should be taken into account for impurity-based band-structure engineering, and may provide a fruitful basis in the search for novel physics.Comment: Main text and supplementar

Demonstration experiments for solid state physics using a table top mechanical Stirling refrigerator

Liquid free cryogenic devices are acquiring importance in basic science and engineering. But they can also lead to improvements in teaching low temperature an solid state physics to graduate students and specialists. Most of the devices are relatively expensive, but small sized equipment is slowly becoming available. Here, we have designed several simple experiments which can be performed using a small Stirling refrigerator. We discuss the measurement of the critical current and temperature of a bulk YBa2Cu3O(7-d) (YBCO) sample, the observation of the levitation of a magnet over a YBCO disk when cooled below the critical temperature and the observation of a phase transition using ac calorimetry. The equipment can be easily handled by students, and also used to teach the principles of liquid free cooling

Insights into the Pharmacokinetics and In Vitro Cell-Based Studies of the Imidazoline I2 Receptor Ligand B06

Abstract: The impact of neurodegenerative diseases (ND) is becoming unbearable for humankind due to their vast prevalence and the lack of efficacious treatments. In this scenario, we focused on imidazoline I2 receptors (I2‐IR) that are widely distributed in the brain and are altered in patients with brain disorders. We took the challenge of modulating I2‐IR by developing structurally new molecules, in particular, a family of bicyclic α‐iminophosphonates, endowed with high affinity and selectivity to these receptors. Treatment of two murine models, one for age‐related cognitive decline and the other for Alzheimer's disease (AD), with representative compound B06 ameliorated their cognitive impairment and improved their behavioural condition. Furthermore, B06 revealed beneficial in vitro ADME‐Tox properties. The pharmacokinetics (PK) and metabolic profile are reported to de‐risk B06 for progressing in the preclinical development. To further characterize the pharmacological properties of B06, we assessed its neuroprotective properties and beneficial effect in an in vitro model of Parkinson's disease (PD). B06 rescued the human dopaminergic cell line SH‐SY5Y from death after treatment with 6‐hydroxydopamine (6‐OHDA) and showed a crucial anti‐inflammatory effect in a cellular model of neuroinflammation. This research reveals B06 as a putative candidate for advancing in the difficult path of drug discovery and supports the modulation of I2‐IR as a fresh approach for the therapy of ND

Deltamethrin resistance in Aedes aegypti results in treatment failure in Merida, Mexico

The operational impact of deltamethrin resistance on the efficacy of indoor insecticide applications to control Aedes aegypti was evaluated in Merida, Mexico. A randomized controlled trial quantified the efficacy of indoor residual spraying (IRS) against adult Ae. aegypti in houses treated with either deltamethrin (to which local Ae. aegypti expressed a high degree of resistance) or bendiocarb (to which local Ae. aegypti were fully susceptible) as compared to untreated control houses. All adult Ae. aegypti infestation indices during 3 months post-spraying were significantly lower in houses treated with bendiocarb compared to untreated houses (odds ratio < 0.75; incidence rate ratio < 0.65) whereas no statistically significant difference was detected between the untreated and the deltamethrin-treated houses. On average, bendiocarb spraying reduced Ae. aegypti abundance by 60% during a 3-month period. Results demonstrate that vector control efficacy can be significantly compromised when the insecticide resistance status of Ae. aegypti populations is not taken into consideration

Reproductive and seminal characteristics of Pelibuey rams infected with Mycobacterium avium subsp. paratuberculosis in the subclinical stage

Objective: To evaluate the reproductive and seminal characteristics of Pelibuey rams infected with Mycobacterium avium subsp. paratuberculosis in the subclinical phase. Design/methodology/approach: In order to determine whether paratuberculosis (PTB) affects the reproductive variables and seminal quality in Pelibuey rams naturally infected with Mycobacterium avium subsp. paratuberculosis (MAP) in the subclinical phase, weekly evaluations were conducted, over a period of two months, of the variables live weight, scrotal circumference, ejaculation latency and seminal characteristics: volume, pH, masal motility and progressive individual motility, concentration, live spermatozoids and dead spermatozoids, in five rams infected by MAP and a further five uninfected rams, of average weight and age 53.58 kg (± 3.26) and 2.91 years (± 0.59), respectively. Results: PTB was not found to affect the reproductive and seminal variables evaluated. Limitations of the study/implications: It would have been convenient to carry out the evaluation of the seminal characteristics for a longer time, however, the sampling was stopped in order to ensure the animal welfare of the rams as far as possible, since they began to show signs of PTB. Findings/Conclusions: The Pelibuey rams diagnosed with PTB in subclinical phase did not present any effect on the reproductive and seminal characteristics. Meanwhile, reproductive management can be carried out with PTB-infected Pelibuey lambs in a subclinical phase.Objective: To evaluate the reproductive and seminal characteristics of Pelibuey rams infected with Mycobacterium avium subsp. paratuberculosis in the subclinical phase. Design/methodology/approach: In order to determine whether paratuberculosis (PTB) affects the reproductive variables and seminal quality in Pelibuey rams naturally infected with Mycobacterium avium subsp. paratuberculosis (MAP) in the subclinical phase, weekly evaluations were conducted, over a period of two months, of the variables live weight, scrotal circumference, ejaculation latency and seminal characteristics: volume, pH, masal motility and progressive individual motility, concentration, live spermatozoids and dead spermatozoids, in five rams infected by MAP and a further five uninfected rams, of average weight and age 53.58 kg (± 3.26) and 2.91 years (± 0.59), respectively. Results: PTB was not found to affect the reproductive and seminal variables evaluated. Limitations of the study/implications: It would have been convenient to carry out the evaluation of the seminal characteristics for a longer time, however, the sampling was stopped in order to ensure the animal welfare of the rams as far as possible, since they began to show signs of PTB. Findings/Conclusions: The Pelibuey rams diagnosed with PTB in subclinical phase did not present any effect on the reproductive and seminal characteristics. Meanwhile, reproductive management can be carried out with PTB-infected Pelibuey lambs in a subclinical phase

Granulocytes-Rich Thrombi in Cerebral Large Vessel Occlusion Are Associated with Increased Stiffness and Poorer Revascularization Outcomes

Acute stroke; Flow cytometry; Mechanical thrombectomyIctus agut; Citometria de flux; Trombectomia mecànicaIctus agudo; Citometría de flujo; Trombectomía mecánicaWe aim to identify a profile of intracranial thrombus resistant to recanalization by mechanical thrombectomy (MT) in acute stroke treatment. The first extracted clot of each MT was analyzed by flow cytometry obtaining the composition of the main leukocyte populations: granulocytes, monocytes, and lymphocytes. Demographics, reperfusion treatment, and grade of recanalization were registered. MT failure (MTF) was defined as final thrombolysis in cerebral infarction score IIa or lower and/or need of permanent intracranial stenting as a rescue therapy. To explore the relationship between stiffness of intracranial clots and cellular composition, unconfined compression tests were performed in other cohorts of cases. Thrombi obtained in 225 patients were analyzed. MTF were observed in 30 cases (13%). MTF was associated with atherosclerosis etiology (33.3% vs. 15.9%; p = 0.021) and higher number of passes (3 vs. 2; p < 0.001). Clot analysis of MTF showed higher percentage of granulocytes [82.46 vs. 68.90% p < 0.001] and lower percentage of monocytes [9.18% vs.17.34%, p < 0.001] in comparison to successful MT cases. The proportion of clot granulocytes (aOR 1.07; 95% CI 1.01–1.14) remained an independent marker of MTF. Among thirty-eight clots mechanically tested, there was a positive correlation between granulocyte proportion and thrombi stiffness (Pearson’s r = 0.35, p = 0.032), with a median clot stiffness of 30.2 (IQR, 18.9–42.7) kPa. Granulocytes-rich thrombi are harder to capture by mechanical thrombectomy due to increased stiffness, so a proportion of intracranial granulocytes might be useful to guide personalized endovascular procedures in acute stroke treatment.Open Access Funding provided by Universitat Autonoma de Barcelona. This work was supported by “Project 355/C/2017, Fundació La Marató de TV3 in Strokes and Traumatic Spinal Cord and Brain Injury, 2017 Call of Projects.

Dyslipidemias and stroke prevention: recommendations of the Study Group of Cerebrovascular Diseases of the Spanish Society of Neurology

Objetivo: Actualizar las recomendaciones de la Sociedad Española de Neurología para la prevención del ictus, tanto primaria como secundaria, en pacientes con dislipidemia. Desarrollo: Se ha realizado una revisión sistemática en Pubmed evaluando los principales aspectos relacionados con el manejo de las dislipidemias en la prevención primaria y secundaria del ictus, elaborándose una serie de recomendaciones relacionadas con los mismos. Conclusiones: En prevención primaria se recomienda determinar el riesgo vascular del paciente con el fin de definir los objetivos de LDLc. En prevención secundaria tras un ictus de origen aterotrombótico se recomienda un objetivo de LDLc < 55 mg/dl, mientras que en ictus isquémicos de origen no aterotrombótico, dado que su relación con dislipidemias es incierta, se establecerán los objetivos en función del grupo de riesgo vascular de cada paciente. Tanto en prevención primaria como secundaria las estatinas son los fármacos de primera elección, pudiendo asociarse ezetimiba y/o inhibidores de PCSK9 en aquellos casos que no alcancen los objetivos terapéuticosObjective We present an update of the Spanish Society of Neurology's recommendations for prevention of both primary and secondary stroke in patients with dyslipidaemia. Development We performed a systematic review to evaluate the main aspects of the management of dyslipidaemias in primary and secondary stroke prevention and establish a series of recommendations. Conclusions In primary prevention, the patient's vascular risk should be determined in order to define target values for low-density lipoprotein cholesterol. In secondary prevention after an atherothrombotic stroke, a target value < 55 mg/dL is recommended; in non-atherothombotic ischaemic strokes, given the unclear relationship with dyslipidaemia, target value should be established according to the vascular risk group of each patient. In both primary and secondary prevention, statins are the drugs of first choice, and ezetimibe and/or PCSK9 inhibitors may be added in patients not achieving the target valu