Un cabinet expose-t-il nécessairement une collection ? Le cas du Cabinet des fleurs de Jean Franeau, un cabinet de regrets

International audienc

Cryogenic Calibration Setup for Broadband Complex Impedance Measurements

Reflection measurements give access to the complex impedance of a material on a wide frequency range. This is of interest to study the dynamical properties of various materials, for instance disordered superconductors. However reflection measurements made at cryogenic temperature suffer from the difficulty to reliably subtract the circuit contribution. Here we report on the design and first tests of a setup able to precisely calibrate in situ the sample reflection, at 4.2 K and up to 2 GHz, by switching and measuring, during the same cool down, the sample and three calibration standards.Comment: (6 pages, 6 figures

Destruction of superconductivity in disordered materials : a dimensional crossover

The disorder-induced Superconductor-to-Insulator Transition in amorphous Nb$_{x}$Si$_{1-x}$ two-dimensional thin films is studied for different niobium compositions $x$ through a variation of the sample thickness $d$. We show that the critical thickness $d_c$, separating a superconducting regime from an insulating one, increases strongly with diminishing $x$, thus attaining values of over 100 {\AA}. The corresponding phase diagram in the $(d, x)$ plane is inferred and related to the three-dimensional situation. The two-dimensional Superconductor-to-Insulator Transition well connects with the three-dimensional Superconductor-to-Metal Transition

Observation of thermally activated glassiness and memory dip in a-NbSi insulating thin films

We present electrical conductance measurements on amorphous NbSi insulating thin films. These films display out-of equilibrium electronic features that are markedly different from what has been reported so far in disordered insulators. Like in the most studied systems (indium oxide and granular Al films), a slow relaxation of the conductance is observed after a quench to liquid helium temperature which gives rise to the growth of a memory dip in MOSFET devices. But unlike in these systems, this memory dip and the related conductance relaxations are still visible up to room temperature, with clear signatures of a temperature dependent dynamics

A length scale for the superconducting Nernst signal above Tc_{c} in Nb0.15_{0.15}Si0.85_{0.85}

We present a study of the Nernst effect in amorphous superconducting thin films of Nb$_{0.15}$Si$_{0.85}$. The field dependence of the Nernst coefficient above T$_{c}$ displays two distinct regimes separated by a field scale set by the Ginzburg-Landau correlation length. A single function $F(\xi)$, with the correlation length as its unique argument set either by the zero-field correlation length (in the low magnetic field limit) or by the magnetic length (in the opposite limit), describes the Nernst coefficient. We conclude that the Nernst signal observed on a wide temperature ($30 \times T_c$) and field ($4 \times B_{c2}$) range is exclusively generated by short-lived Cooper pairs.Comment: 4 pages, 4 figure

Magnetic field-induced quantum superconductor-insulator transition in Nb0.15Si0.85Nb_{0.15}Si_{0.85}

A study of magnetic-field tuned superconductor-insulator transitions in amorphous $Nb_{0.15}Si_{0.85}$ thin films shows that quantum superconductor-insulator transitions are characterized by an unambiguous signature -- a kink in the temperature profile of the critical magnetic field. Using this criterion, we show that the nature of the magnetic-field tuned superconductor-insulator transition depends on the orientation of the field with respect to the film. For perpendicular magnetic field, the transition is controlled by quantum fluctuations with indications for the existence of a Bose insulator; while for parallel magnetic field, the transition is classical, driven by the breaking of Cooper pairs at the temperature dependent critical field $H_{c2}$.Comment: 5 pages, 4 figure

Effect of annealing on the superconducting properties of a-Nb(x)Si(1-x) thin films

a-Nb(x)Si(1-x) thin films with thicknesses down to 25 {\AA} have been structurally characterized by TEM (Transmission Electron Microscopy) measurements. As-deposited or annealed films are shown to be continuous and homogeneous in composition and thickness, up to an annealing temperature of 500{\deg}C. We have carried out low temperature transport measurements on these films close to the superconductor-to-insulator transition (SIT), and shown a qualitative difference between the effect of annealing or composition, and a reduction of the film thickness on the superconducting properties of a-NbSi. These results question the pertinence of the sheet resistance R_square as the relevant parameter to describe the SIT.Comment: 9 pages, 12 figure

Exportación de ropa para bebés elaborada en base a tejido de punto (hilos) de algodón orgánico a Colombia

El presente plan de negocio para exportación se plantea a partir de la idea y deseo de querer fabricar ropa con insumos orgánicos que permitan el cuidado de la piel y la protección del medio ambiente para bebés de 0 a 2 años. Se establecen tres importantes mercados objetivos que son Bogotá, Cali y Medellín situados en Colombia. Dichos mercados cuentan con una alta demanda por productos de calidad y de diseños exclusivos que al mismo tiempo sean socialmente responsables con el medio ambiente. Nuestro mercado meta en estas tres ciudades son los niños entre 0 y 2 años que tengan padres de familia con un nivel socio-económico por encima del medio-alto de ingresos y con alta preocupación por el cuidado de la salud del bebé. Además, se evaluarán los diversos canales de distribución donde se desenvolverá la empresa, así como las amenazas y las oportunidades que este mercado colombiano nos ofrece. También se analizarán las ventajas competitivas que se tienen que desarrollar, el manejo con los proveedores y la competencia en el mercado destino para conseguir concretar la situación real del mercado. La finalidad de la empresa es posicionarse en el mercado internacional con innovadoras prendas que logren satisfacer los gustos y necesidades del consumidor. Finalmente, para analizar la viabilidad del proyecto se efectuará una proyección a 5 años que establecerán fases de crecimiento determinadas que presentará la empresa El Arrullo. Para esto se efectúa una proyección de ventas y costos para desarrollar un flujo de caja de estos períodos y obtener el VAN del proyecto y determinar si es o no rentable y definir los riesgos que pudiesen existir

Unhealthy Lifestyle Behaviors and Dietary Patterns Lead to Mental Distress?: An Analysis of Mental Distress Through Diet and Lifestyle Behaviors

Research has identified several relationships between diet, mental distress, and healthy lifestyle behaviors. One particularly popular diet type in America is the Western diet, which is filled with many processed and high sugar foods. This study examined the Western diet, and various more nutritious diets and their effect on participants\u27 mental distress as well as their lifestyle behaviors. The experiment utilized an anonymous survey consisting of questions relating to diet, mental distress and lifestyle choices. A survey was released to a mid-sized northeastern university. Various college aged students from the university (N=161) and students from other universities (N=27) completed the survey. The survey was conducted to participants through several social media outlets, and also over text messages. Various questions from the survey were analyzed, such as (1) “In the past 7 days, how many times did you eat breakfast?” and (2) “In the last month, how often have you felt confident about your ability to handle your personal problems?”. Survey results were analyzed using SPSS version 25.0. Results indicated there is a positive correlation between healthy dietary patterns and healthy lifestyle behaviors and a negative correlation between healthy dietary patterns and mental distress. Results supported that hypothesis that various types of nutrient dense food led to decreased feelings of depression and hopelessness. Results support that healthy lifestyle behaviors and healthy dietary patterns improve overall health and decrease mental distress. It is recommended to increase sample size to further study and understand these relationships.https://orb.binghamton.edu/research_days_posters_2022/1109/thumbnail.jp

A course on Climate Change and Sustainable Building Design

We present an intermediate-level course on sustainable physics, which combines lectures and student projects. Sustainable physics concepts are progressively introduced through both a global and a specialized perspective: climate change and building design. The lectures and hands-on activities on both topics show how they share common concepts and provide complementary points of view. Climate change mitigation and adaptation are touched on via student group projects, where they are asked to tackle a specific question of their choosing via reviews of the literature, modeling or experiments.Comment: 11 pages + Supp Matt 20 page