Isotope effect on the E2g phonon and mesoscopic phase separation near the electronic topological transition in Mg1-xAlxB2

We report the boron isotope effect on the E2g phonon mode by micro-Raman spectroscopy on the ternary Mg1-xAlxB2 system, synthesized with pure isotopes 10B and 11B. The isotope coefficient on the phonon frequency is near 0.5 in the full range decreasing near x = 0. The intraband electron-phonon (e-ph) coupling, for the electrons in the sigma band, has been extracted from the E2g line-width and frequency softening. Tuning the Fermi energy near the electronic topological transition (ETT), where the sigma Fermi surface changes from 2D to 3D topology the E2g mode, shows the known Kohn anomaly on the 2D side of the ETT and a splitting of the E2g phonon frequency into a hard and soft component from x = 0 to x = 0.28. The results suggest a minor role of the intraband phonon mediated pairing in the control of the high critical temperature in Mg1-xAlxB2. The common physical features of diborides with the novel multigap FeAs-based superconductors and cuprates is discussed.Comment: 19 pages, 6 figure

The BCC Unit Cell for Latticed SLM Parts; Mechanical Properties as a Function of Cell Size

The existing framework describing the mechanical properties of lattices places strong emphasis on one important property, the relative density of the repeating cells. In this work, we explore the effects of cell size, attempting to construct more complete models for the performance of lattices. This was achieved by examining the elastic modulus and ultimate tensile strength of latticed parts with a range of unit cell sizes and fixed density. The parts were produced by selective laser melting (SLM). The examined cell type was body-centred-cubic (BCC), a cell of high relevance for SLM because of its self-supporting structure. We obtained power law relationships for the mechanical properties of our latticed specimens as a function of cell size, which are similar in form to the existing laws for the density dependence. These can be used to predict the properties of latticed column structures comprised of BCC cells, and may be easily amended for other situations. In addition, we propose a novel way to analyse the elastic modulus data, which may lead to more general models, applicable to parts of varying size. Lastly, our general methodology may be of use in future studies which explore the other parameters that determine lattice performance; the choice of cell type, the global shape of the lattice structure and the type of stress.Mechanical Engineerin

Verificación de los pronósticos de temperaturas mínimas y máximas para el Observatorio Central Buenos Aires

Se compararon los pronósticos diarios con las observaciones correspondientes para el período 1974-81. La evaluación del error medio, el error absoluto medio, el error cuadrático medio, el error cuadrático medio por persistencia y el coeficiente de correlación entre la variación pronosticada y observada, muestra que el método sinóptico-subjetivo que se emplea supera al pronóstico por persistencia y que existe la tendencia a dar una temperatura mínima demasiado baja, especialmente en otoño e invierno. Además, la bondad de los pronósticos no ha sufrido cambio alguno del principio al final del período investigado, lo que indica que para mejorar los pronósticos debe recurrirse a otros métodos.The daily forecasts were contrasted with the corresponding observations for the period 1974-81. The evaluation of mean error, absolute mean error, root mean-square error, root mean-square error for persistence and the correlation coefficient between forecasted and observed variations all show that the subjetive synoptic forecast method used, is somewhat better than using the persistence one, and that there is a tendency to forecast minimum temperatures too low specially in autumm and winter. Besides the goodness of the forecasts has not shown any change since the beginning of the investigated period, so that to achieve any improvement should be developed other forecast methods.Asociación Argentina de Geofísicos y Geodesta

On the development of twinning-induced plasticity in additively manufactured 316L stainless steel

A report on twinning-induced plasticity in 316L stainless steel manufactured by metal additive manufacturing (AM) is presented. A tapered tensile test geometry was used which enabled the investigation of twin formation over a range of strain levels in a single specimen. Hardness and twinning concentration were observed to increase with strain up to peak values of 380 ± 10 HV and 28 ± 4%, respectively. Furthermore, twin formation was found to be regulated by grain size and crystal texture. This methodology can be applied to new AM materials development and will inform the design of energy-absorbing structures that maximise the benefits of AM design and strain-hardenable materials

Neuropsychological deficits in young drug addicts

Background: Adolescence is a highly vulnerable age for experimenting with drugs; increasing evidence attests that several substances might have detrimental effects on cognitive functioning in this developmental phase, when prefrontal brain areas are still immature and may actually be the main target of the neurotoxic effects of drugs. There are still, in any case, too few studies that specifically address early adulthood. Aim: The present study aims to investigate neuropsychological performance in young drug addicts in residential treatment (aged 18-24). Methods: 41 young drug addicts, after admission to residential treatment, were compared with 27 subjects in the control group. A battery of neuropsychological tests (Brief Neuropsychological Exam-2) was administered to detect possible cognitive impairments. Descriptive and non-parametric statistics (Pearson’s chi square test) were performed. Results and conclusions: Findings suggest that drug dependence in youth is distinguished by neuropsychological deficits, in particular, attention and executive function impairments – issues that now call for tailored and innovative treatment approaches

Experimental observation of controllable kinetic constraints in a cold atomic gas

Many-body systems relaxing to equilibrium can exhibit complex dynamics even if their steady state is trivial. In situations where relaxation requires highly constrained local particle rearrangements, such as in glassy systems, this dynamics can be difficult to analyze from first principles. The essential physical ingredients, however, can be captured by idealized lattice models with so-called kinetic constraints. While so far constrained dynamics has been considered mostly as an effective and idealized theoretical description of complex relaxation, here we experimentally realize a many-body system exhibiting manifest kinetic constraints and measure its dynamical properties. In the cold Rydberg gas used in our experiments, the nature of the kinetic constraints can be tailored through the detuning of the excitation lasers from resonance. The system undergoes a dynamics which is characterized by pronounced spatial correlations or anticorrelations, depending on the detuning. Our results confirm recent theoretical predictions, and highlight the analogy between the dynamics of interacting Rydberg gases and that of certain soft-matter systems

Diagnostic accuracy of ultrasonographic features in detecting thyroid cancer in the transition age: a meta-analysis

Context: Significant uncertainty exists about the diagnostic accuracy of ultrasonographic (US) features used to predict the risk of thyroid cancer in the pediatric population. Moreover, there are no specific indications for thyroid nodule evaluation in patients during the transition age. Objective: The meta-analysis aimed to address the following question: which thyroid nodule US features have the highest accuracy in predicting malignancy in the transition age. Methods: We performed a meta-analysis of observational/cohort/diagnostic accuracy studies dealing with thyroid nodule sonography, reporting US features, and using histology as a reference standard for the diagnosis of malignancy and histology or cytology for the diagnosis of benignity in the transition age (mean/median age 12-21 years). Results: The inclusion criteria were met by 14 studies, published between 2005 and 2020, including 1306 thyroid nodules (mean size 17.9 mm) from 1168 subjects. The frequency of thyroid cancer was 36.6%. The US features with the highest diagnostic odds ratio (DOR) for malignancy were the presence of suspicious lymph nodes (DOR: 56.0 (95% CI: 26.0-119.0)), a 'taller than wide' shape of the nodule (6.0 (95% CI: 2.0-16.0)), the presence of microcalcifications (13.0 (95% CI: 6.0-29.0)) and irregular margins (9.0 (95% CI: 5.0- 17.0)). Heterogeneity among the studies was substantial. Conclusions: Following the diagnosis of a thyroid nodule in the transition age, a thorough US examination of the neck is warranted. The detection of suspicious lymph nodes and/ or thyroid nodules with a 'taller than wide' shape, microcalcifications, and irregular margins is associated with the highest risk of malignancy in the selection of nodules candidates for biopsy

Inclusion of a degron reduces levelsof undesired inteins after AAV-mediated proteintrans-splicing in the retina

Split intein-mediated protein trans-splicing expands AAV transfer capacity, thus overcoming the limited AAV cargo. However, non-mammalian inteins persist as trans-splicing by-products, and this could raise safety concerns for AAV intein clinical applications. In this study, we tested the ability of several degrons to selectively decrease levels of inteins after protein trans-splicing and found that a version of E. coli dihydrofolate reductase, which we have shortened to better fit into the AAV vector, is the most effective. We show that subretinal administration of AAV intein armed with this short degron is both safe and effective in a mouse model of Stargardt disease (STGD1), which is the most common form of inherited macular degeneration in humans. This supports the use of optimized AAV intein for gene therapy of both STGD1 and other conditions that require transfer of large genes

Insights into drop-on-demand metal additive manufacturing through an integrated experimental and computational study

Drop-on-demand metal jetting is a recent additive manufacturing technology opening new opportunities for the fabrication of complex single and multi-metal components. MetalJet, the Océ developed technique used in this study, has the capacity to produce molten micro-droplets (60-80 µm) at temperatures up to 2000 °C to form single and multi-material objects. Applications for this technology include flexible circuits, advanced electronic components and biotechnologies. However, full exploitation of this technology is impeded by a lack of understanding of various aspects of the process, including droplet bonding and interface formation, residual stress development and the evolution of microstructure. This paper uses an integrated numerical and experimental approach to provide insights into these research questions. Thermal models were used to investigate droplet-to-substrate adhesion and explain the experimentally-observed morphology of droplets. Thermo-mechanical modelling was used to investigate residual stress development and its role in the observed droplet warping and delamination. The knowledge obtained from this study can be used to underpin the development of functional multi-material printing