Magnetism of two-dimensional defects in Pd: stacking faults, twin boundaries and surfaces

Careful first-principles density functional calculations reveal the importance of hexagonal versus cubic stacking of closed packed planes of Pd as far as local magnetic properties are concerned. We find that, contrary to the stable face centered cubic phase, which is paramagnetic, the hexagonal close-packed phase of Pd is ferromagnetic with a magnetic moment of 0.35 $\mu_{B}$/atom. Our results show that two-dimensional defects with local hcp stacking, like twin boundaries and stacking faults, in the otherwise fcc Pd structure, increase the magnetic susceptibility. The (111) surface also increases the magnetic susceptibility and it becomes ferromagnetic in combination with an individual stacking fault or twin boundary close to it. On the contrary, we find that the (100) surface decreases the tendency to ferromagnetism. The results are consistent with the magnetic moment recently observed in small Pd nanoparticles, with a large surface area and a high concentration of two-dimensional stacking defects.Comment: 8 pages, 10 figure

Progressive myoclonus epilepsy KCNC1 variant causes a developmental dendritopathy

OBJECTIVE: Mutations in KCNC1 can cause severe neurological dysfunction, including intellectual disability, epilepsy, and ataxia. The Arg320His variant, which occurs in the voltage-sensing domain of the channel, causes a highly penetrant and specific form of progressive myoclonus epilepsy with severe ataxia, designated myoclonus epilepsy and ataxia due to potassium channel mutation (MEAK). KCNC1 encodes the voltage-gated potassium channel KV 3.1, a channel that is important for enabling high-frequency firing in interneurons, raising the possibility that MEAK is associated with reduced interneuronal function. METHODS: To determine how this variant triggers MEAK, we expressed KV 3.1bR320H in cortical interneurons in vitro and investigated the effects on neuronal function and morphology. We also performed electrophysiological recordings of oocytes expressing KV 3.1b to determine whether the mutation introduces gating pore currents. RESULTS: Expression of the KV 3.1bR320H variant profoundly reduced excitability of mature cortical interneurons, and cells expressing these channels were unable to support high-frequency firing. The mutant channel also had an unexpected effect on morphology, severely impairing neurite development and interneuron viability, an effect that could not be rescued by blocking KV 3 channels. Oocyte recordings confirmed that in the adult KV 3.1b isoform, R320H confers a dominant negative loss-of-function effect by slowing channel activation, but does not introduce potentially toxic gating pore currents. SIGNIFICANCE: Overall, our data suggest that, in addition to the regulation of high-frequency firing, KV 3.1 channels play a hitherto unrecognized role in neuronal development. MEAK may be described as a developmental dendritopathy

Neuroimagen del linfoma primario del sistema nervioso central en pacientes inmunodeprimidos

ResumenObjetivosEl linfoma primario del sistema nervioso central (LPSNC) es una entidad rara con un pronóstico fatal. Dado el aumento en el número de casos con inmunosupresión adquirida, nuestros objetivos son estudiar las características epidemiológicas y neurorradiológicas de aquellos pacientes inmunodeprimidos con diagnóstico de LPSNC con afectación cerebral e investigar si existen diferencias entre los pacientes con el virus de la inmunodeficiencia humana (VIH) positivo y negativo.Materiales y métodosSe realizó un estudio descriptivo y retrospectivo de los pacientes inmunodeprimidos con afectación cerebral por LPSNC, diagnosticados durante los últimos 13 años en 2 hospitales de referencia. Se evaluaron múltiples variables. El nivel de significación estadística utilizado fue p<0,05.ResultadosEl grupo VIH-positivo tenía una media de edad de 36,82±5,4 años, frente a los 55,60 ± 21,43 años de los pacientes VIH-negativo (p<0,022). Los pacientes VIH-positivo tuvieron una media de 1,27 ± 0,65 lesiones por paciente, mientras que en el grupo VIH-negativo fue de 2,60 ± 1,78 (p<0,039). El 18,2% (n=2) del grupo VIH-positivo y el 80% (n=8) del grupo VIH-negativo presentaron lesiones homogéneas (p<0,005). Ningún paciente VIH-positivo tuvo afectación del cuerpo calloso, pero el grupo VIH-negativo presentó un 50% (n=5) de afectación (p<0,012).ConclusionesEl LPSNC en pacientes inmunodeprimidos puede presentar múltiples características en las imágenes. Existen diferencias entre los pacientes VIH positivo y negativo, por lo que es importante reconocerlas para establecer un manejo y tratamiento diferente entre ambos grupos.AbstractPurposesPrimary central nervous system lymphoma (PCNSL) is a rare tumour with poor prognosis. Due to the increased number of patients with acquired immunodeficiency, our purposes are to describe epidemiological and imaging findings in immunodeficient patients with PCNSL of the brain and to study the differences between HIV-positive and HIV-negative patients with PCNSL.Materials and methodsA retrospective, descriptive study was performed with immunodeficient patients diagnosed of PCNSL of the brain during the last 13 years in two reference hospitals. Twenty-one patients fulfilled the inclusion criteria. Multiple variables were evaluated. Significance was defined as p<0.05.ResultsHIV-positive group was a mean age of 36,82±5,4 years and the mean age in HIV-negative group was 55,60±21,43 years (p<0,022). The mean number of lesions was 1,27±0,65 in HIV-positive group and 2,60±1,78 in HIV-negative group (p<0,039). The lesions were homogeneous in 18,2% (n=2) HIV-positive group and 80% (n=8) in HIV-negative group (p<0,005). No HIV-positive patient and 50% (n=5) of HIV-negative patients showed corpus callosum involvement (p<0,012).ConclusionsPCNSL in immunodeficient patients is associated with a large spectrum of radiological findings. There were differences between HIV-positive and HIV-negative patients, is important recognize these differences as the therapeutic management of these two groups vary

Las microexposiciones del parque de las ciencias de Granada. otra forma de enseñar y aprender ciencias

Los museos de Ciencias tienen un papel importante en la tarea de proporcionar a estudiantes y personas adultas una formación científica básica para desenvolverse en el mundo actual. El Parque de las Ciencias de Granada, en colaboración con la Consejería de Educación de la Junta de Andalucía, elabora desde hace dos años una serie de microexposiciones que presta a los centros educativos para que sea un grupo de estudiantes, con su profesor, quien se responsabilice de organizarlas y presentarlas en el centro. El alumnado tiene así ocasión de aprender ciencias de otra forma, investigando y enseñando a los demás. En este trabajo se describen las características de las microexposiciones, especialmente de la dedicada a Faraday, las actividades paralelas organizadas por los centros al presentarla y la valoración que hace el profesorado de la experiencia

Las microexposiciones del parque de las ciencias de Granada. otra forma de enseñar y aprender ciencias

Los museos de Ciencias tienen un papel importante en la tarea de proporcionar a estudiantes y personas adultas una formación científica básica para desenvolverse en el mundo actual. El Parque de las Ciencias de Granada, en colaboración con la Consejería de Educación de la Junta de Andalucía, elabora desde hace dos años una serie de microexposiciones que presta a los centros educativos para que sea un grupo de estudiantes, con su profesor, quien se responsabilice de organizarlas y presentarlas en el centro. El alumnado tiene así ocasión de aprender ciencias de otra forma, investigando y enseñando a los demás. En este trabajo se describen las características de las microexposiciones, especialmente de la dedicada a Faraday, las actividades paralelas organizadas por los centros al presentarla y la valoración que hace el profesorado de la experiencia

Magnetic and microstructural analysis of palladium nanoparticles with different capping systems

Palladium nanoparticles capped with different protective systems in a size range between 1.2 and 2.4 nm have been obtained by varying the preparation chemical method. Magnetization curves for all the samples show hysteresis loops, evidencing a ferromagnetic or a permanent magnetism in the nanoparticles. The microstructure of the nanoparticles has been analyzed by x-ray absorption and transmission electron microscopy. The nature of the magnetic behavior found for all these Pd nanoparticles (NPs) is different depending on their sizes and structural features and is explained on the basis of two different suggested mechanisms. The particles protected by means of a surfactant (tetralkylammonium salts), present a ferromagnetic order related to the factors increasing the density of states just below the Fermi level. Whereas, when the nanoparticles are stabilized by covalent bonds with protective species (thiol derivatized alkane chains or surface oxidized Pd NPs), the increase of the 4d density of holes, localized by the bonded atoms (S or O), is giving rise to the observed ferromagneticlike behavior

Climatic variability and decline of Atlantic Iberian Nephrops fisheries

PresentationNephrops landings and landings per unit effort from the mixed bottom trawl fishery in the northwest Spain have a marked downward trend since the earliest 90s. Since 2006, a recovery plan has been developed but improvement signs have not been detected up to now, and the fishery shows currently a depleted state. Multiple environmental-related causal mechanisms may interact in this decline other than fishing pressure. Climatic variability of the region was characterized using series (1950-2010) of teleconnection patterns (North Atlantic Oscillation index, Eastern Atlantic index, Scandinavian index and Poleward index). Fishery Nephrops data and climatic series were jointly analyzed. The aim was to indentify relationships between the Nephrops dynamics and the environmental system, and the mechanisms that could have an influence on the biological fluctuation

The poor accuracy of D-dimer for the diagnosis of prosthetic joint infection but its potential usefulness in early postoperative infections following revision arthroplasty for aseptic loosening

Background: D-dimer was introduced in 2018 as an alternative biomarker for C-reactive protein (CRP) in the diagnostic of prosthetic joint infection (PJI) criteria of the Musculoskeletal Infection Society. We assessed the accuracy of plasma D-dimer for the diagnosis of early, delayed, and late PJI according to Infectious Diseases Society of America (IDSA) criteria, and whether persistently high levels of D-dimer in cases of aseptic loosening (AL) may be predictive of subsequent implant-related infection. Methods: A prospective study of a consecutive series of 187 revision arthroplasties was performed at a single institution.Septic (n = 39) and aseptic revisions (n = 141) were classified based on IDSA criteria. Preoperative assessment of CRP, erythrocyte sedimentation rate (ESR) and D-dimer was performed. Receiver operating curves were used to determine maximum sensitivity and specificity of the biomarkers. The natural progress of D-dimer for AL cases was followed up either until the date of implant-related infection at any time during the first year or 1 year after revision in patients without failure. Clinical outcomes for those AL cases included infection-related failure that required a new surgery or need for antibiotic suppression. Results: Preoperative D-dimer level was significantly higher in PJI cases than in AL cases (p = 0.000). The optimal threshold of D-dimer for the diagnosis of PJI was 1167 ng/mL. For overall diagnosis of PJI, C-reactive protein (CRP) achieved the highest sensitivity (84.6%), followed by erythrocyte sedimentation rate (ESR) and D-dimer (82% and 71.8%, respectively). Plasma D-dimer sensitivity was lower for all PJI types. When combinations of 2 tests were studied, the combined use of ESR and CRP achieved the best accuracy for all types of PJI (76.9%). 4.25% of AL cases had implant failure due to implant-related infection during the first year after the index revision arthroplasty, only the cases with early failure maintained high D-dimer levels