Weak localization corrections to the thermal conductivity in ss-wave superconductors

We study the thermal conductivity in disordered $s$-wave superconductors. Expanding on previous works for normal metals, we develop a formalism that tackles particle diffusion as well as the weak localization (WL) and weak anti-localization (WAL) effects. Using a Green's functions diagrammatic technique, which takes into account the superconducting nature of the system by working in Nambu space, we identify the system's low-energy modes, the diffuson and the Cooperon. The time scales that characterize the diffusive regime are energy dependent; this is in contrast with the the normal state, where the relevant time scale is the mean free time $\tau_e$, independent of energy. The energy dependence introduces a novel energy scale $\varepsilon_*$, which in disordered superconductors ($\tau_e \Delta\ll 1$, with $\Delta$ the gap) is given by $\varepsilon_* = \sqrt{\Delta/\tau_e}$. From the diffusive behavior of the low-energy modes, we obtain the WL correction to the thermal conductivity. We give explicitly expressions in two dimensions. We determine the regimes in which the correction depends explicitly on $\varepsilon_*$ and propose an optimal regime to verify our results in an experiment.Comment: 15 pages, 6 figure

Gang membership, drug sales, violence, and guns

The purpose of this study is to examine three factors relating to drug arrests using secondary data analysis. First, ethnic characteristics of a dealer were analyzed according to the location from where they sold their product. Next, possible factors associated with a police officer using force at the time of a drug arrest were also analyzed. Finally, factors associated with a gun being present at the time of a drug arrest were also analyzed

Skills or Degree? The Rise of Skill-Based Hiring for AI and Green Jobs

For emerging professions, such as jobs in the field of Artificial Intelligence (AI) or sustainability (green), labour supply does not meet industry demand. In this scenario of labour shortages, our work aims to understand whether employers have started focusing on individual skills rather than on formal qualifications in their recruiting. By analysing a large time series dataset of around one million online job vacancies between 2019 and 2022 from the UK and drawing on diverse literature on technological change and labour market signalling, we provide evidence that employers have started so-called "skill-based hiring" for AI and green roles, as more flexible hiring practices allow them to increase the available talent pool. In our observation period the demand for AI roles grew twice as much as average labour demand. At the same time, the mention of university education for AI roles declined by 23%, while AI roles advertise five times as many skills as job postings on average. Our regression analysis also shows that university degrees no longer show an educational premium for AI roles, while for green positions the educational premium persists. In contrast, AI skills have a wage premium of 16%, similar to having a PhD (17%). Our work recommends making use of alternative skill building formats such as apprenticeships, on-the-job training, MOOCs, vocational education and training, micro-certificates, and online bootcamps to use human capital to its full potential and to tackle talent shortages.Comment: 38 pages, 13 figures, 3 table

Long-range exchange interaction between spin qubits mediated by a superconducting link at finite magnetic field

Solid state spin qubits are promising candidates for the realization of a quantum computer due to their long coherence times and easy electrical manipulation. However, spin-spin interactions, which are needed for entangling gates, have only limited range as they generally rely on tunneling between neighboring quantum dots. This severely constrains scalability. Proposals to extend the interaction range generally focus on coherent electron transport between dots or on extending the coupling range. Here, we study a setup where such an extension is obtained by using a superconductor as a quantum mediator. Because of its gap, the superconductor effectively acts as a long tunnel barrier. We analyze the impact of spin-orbit (SO) coupling, external magnetic fields, and the geometry of the superconductor. We show that while spin non-conserving tunneling between the dots and the superconductor due to SO coupling does not affect the exchange interaction, strong SO scattering in the superconducting bulk is detrimental. Moreover, we find that the addition of an external magnetic field decreases the strength of the exchange interaction. Fortunately, the geometry of the superconducting link offers a lot of room to optimize the interaction range, with gains of over an order of magnitude from a 2D film to a quasi-1D strip. We estimate that for superconductors with weak SO coupling (\textit{e.g.}, aluminum) exchange rates of up to 100\,MHz over a micron-scale range can be achieved with this setup in the presence of magnetic fields of the order of 100\,mT

Estudio de opinion a los egresados de Ingenieria Comercial de la Universidad de Talca Cohortes 1992-2000

286 p.El proceso de acreditación internacional de la Facultad de Ciencias Empresariales (FACE) de la Universidad De Talca (UTALCA) requiere disponer de información respecto a la opinión que tienen los egresados de Ingeniería Comercial de la UTALCA, de la calidad de la educación, en dos dimensiones: habilidades técnicas y habilidades humanas y conceptuales. Como dicho proceso obliga a la evaluación regular de los destinos ocupacionales, aquí se inicia dicho estudio con la descripción del perfil laboral como evolución laboral, destino y nivel ocupacional actual. Además se evaluó la infraestructura, apoyo técnico y recursos para la educación que presto la UTALCA y se consulto sobre el conocimiento e interés respecto a los programas de perfeccionamiento que actualmente ofrece la FACE. La investigación es de tipo descriptivo concluyente, de corte transversal y por estratos determinados por cohorte desde el año 1992 al ano 2000. El estudio se realizo por medio de una encuesta que se instrumenta con un cuestionario estructurado, aplicado a una muestra estadística de egresados que residen en la ciudad de Talca y la Región Metropolitana (RM). Los resultados fueron analizados en forma descriptiva inferencial. Se concluye que los egresados tienen una buena percepción respecto a la formación recibida a nivel global. Para mejoramiento prioritario se menciona: Idiomas, Manejo de base de datos, Habilidad en expresión oral y escrita, Habilidad en dirección de empresas. Los docentes fueron bien calificados respecto a: Experiencia profesional y Calidad expositiva. El nivel de ocupación de los egresados es bueno, y en la progresión laboral se observa una tendencia positiva, con aumentos graduales de remuneración, ascensos y evolución en el destino ocupacional. La investigación logro estructurar un instrumento que permite medir variables que proporcionan información respecto al desarrollo profesional y la percepción de la educación después del egreso

The HD5980 multiple system: Masses and evolutionary status

New spectroscopic observations of the LBV/WR multiple system HD5980 in the Small Magellanic Cloud are used to address the question of the masses and evolutionary status of the two very luminous stars in the 19.3d eclipsing binary system. Two distinct components of the N V 4944 A line are detected in emission and their radial velocity variations are used to derive masses of 61 and 66 Mo, under the assumption that binary interaction effects on this atomic transition are negligible. We propose that this binary system is the product of quasi-chemically homogeneous evolution with little or no mass transfer. Thus, both of these binary stars may be candidates for gamma-ray burst progenitors or even pair instability supernovae. Analysis of the photospheric absorption lines belonging to the third-light object in the system confirm that it consists of an O-type star in a 96.56d eccentric orbit (e=0.82) around an unseen companion. The 5:1 period ratio and high eccentricities of the two binaries suggest that they may constitute a hierarchical quadruple system.Comment: 27 pages, 8 tables, 15 figures; accepted A

Target detection in insects: optical, neural and behavioral optimizations.

This is the final version of the article. It first appeared from Elsevier via https://doi.org/10.1016/j.conb.2016.09.001Motion vision provides important cues for many tasks. Flying insects, for example, may pursue small, fast moving targets for mating or feeding purposes, even when these are detected against self-generated optic flow. Since insects are small, with size-constrained eyes and brains, they have evolved to optimize their optical, neural and behavioral target visualization solutions. Indeed, even if evolutionarily distant insects display different pursuit strategies, target neuron physiology is strikingly similar. Furthermore, the coarse spatial resolution of the insect compound eye might actually be beneficial when it comes to detection of moving targets. In conclusion, tiny insects show higher than expected performance in target visualization tasks.Air Force Office of Scientific Research (Grant ID: FA9550-15-1-0188

Structure of staminate flowers, microsporogenesis, and microgametogenesis in Helosis cayennensis var. cayennensis (Balanophoraceae)

Se analizó la estructura de las flores masculinas de Helosis cayennensis (Sw.) Spreng. var. cayennensis con microscopía óptica y electrónica de barrido y se estudió la microesporogénesis y la microgametogénesis. Las flores funcionalmente unisexuales se encuentran embebidas en una densacapa de tricomas uniseriados. Las flores estaminadas presentan un perianto tubular, 3-lobado, con tépalos biestratificados y sin vascularización. Androceo formado por tres estambres con filamentos y tecas connadas en un sinandro. Las flores presentan un pistilodio central sin desarrollo de megagametofito. Los filamentos estaminales, con un solo haz vascular, están soldados próximalmente al tubo del perianto y hacia la parte distal son libres a lo largo de un corto trecho. La porción apical del sinandro está formada por nueve sacos polínicos: seis externos ubicados lateralmente en cada filamento y tres sacos internos de mayor longitud. La pared de la antera consta de epidermis, dos estratos parietales colapsados a la madurez de la antera y un tapetum secretor uninucleado. No posee endotecio. Durante la microesporogénesis las células madres de las micrósporas producen por meiosis tétradas de micrósporas, la citocinesis es simultánea y se forman tétradas de disposición tetraédrica. Cuando los granos de polen se encuentran en estado tricelular, el sinandro emerge de la masa de tricomas y la dehiscencia se produce por aberturas apicales longitudinales. Como conclusión se observó que a pesar de la extrema reducción de las flores, las características anatómicas y los procesos de esporogénesis y gametogénesis de las flores estaminadas de H. cayennensis son perfectamente normales y siguen patrones usuales, siendo muy similares a otros géneros de holoparásitas estudiadas de la subfamilia Helosidoideae. Las porciones estériles, tanto de las flores como de la inflorescencia, presentan las mismas características aberrantes ya descritas en el cuerpo vegetativo de esta especieWe analyzed the microgametogenesis and microsporogenesis of the male flowers of the holoparasitic Helosis cayennensis (Sw.) Spreng. var. cayennensis using optical and scanning electron microscopy. The unisexual flowers are embedded in a dense mass of uniseriate trichomes (filariae). Male flowers have a tubular 3-lobed perianth, with bilayered and non vascularized tepals. The androecium consists of three stamens with filaments and thecae connated into a synandrium. It has adnate a free central pistillode without megagametophyte. Staminal filaments, fused at their base to the perianth tube and distally free along a short section, have a single vascular bundle. The distal portion of the synandrium is formed by nine pollen sacs: six outer sacs are located laterally to each filament and three longer inner sacs. The anther wall consists of the epidermis, two parietal layers (that collapse at anther maturity), and an uninucleate secretory tapetum. There is no endothecium. During microsporogenesis, the stem cells produce tetrads of microspores by meiosis. The cytokinesis is simultaneous, forming tetrahedrally arranged tetrads. When pollen grains are in the tricellular state, the synandrium emerges from the mass of filariae, and anthers dehiscence occurs apically through longitudinal slits. In conclusion, despite the extreme reduction of flowers, the anatomic characteristics and gametophyte development of staminate flowers of H. cayennensis are perfectly normal and functional. They are thus highly similar to other genera of the holoparasitic subfamily Helosidoideae. Sterile parts of flowers and inflorescence maintain the same distinctive and aberrant features of the plant vegetative parts.Fil: Gonzalez, Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Nordeste. Instituto de Botánica del Nordeste (i); Argentina;Fil: Popoff, Orlando Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Nordeste. Instituto de Botánica del Nordeste (i); Argentina;Fil: Salgado Laurenti, Cristina Renee. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Nordeste. Instituto de Botánica del Nordeste (i); Argentina

Configuración de servicio IPTV y Calidad de servicio QoS en Institución Educativa y todas sus sedes

El desarrollo del presente trabajo consiste en describir los pasos para configurar un servicio básico de IPTV, y es sobre este servicio que se define un plan de calidad de Servicio (QoS, Quality of Service), que incluya los siguientes porcentajes sobre el ancho de banda total separando tráficos mediante definición de clases y de la siguiente manera: 10% del ancho de banda total para tráfico web, 15% para tráfico de voz y 20% para tráfico de streaming de video. El servicio de IPTV, se configura mediante el simulador gráfico de red GNS3 usando una máquina virtual a partir del análisis acerca de IPTV, se continua con la implementación IPTV Multicast entre las sedes del escenario de red, el cual permite transferir contenidos multimedia entre las sedes, y para esto se habilitan los protocolos de enrutamiento, Multicast, RTP, entre otros. De esta manera se hace posible la configuración de servicio IPTV más la Calidad de servicio QoS.The development of the present work consists of describing the steps to configure a basic IPTV service, and it is on this service that a Quality of Service (QoS, Quality of Service) plan is defined, which includes the following percentages on the bandwidth total by separating traffic by class definition and as follows: 10% of the total bandwidth for web traffic, 15% for voice traffic and 20% for video streaming traffic. The IPTV service is configured through the graphical simulator of the GNS3 network using a virtual machine based on the analysis of IPTV, the IPTV Multicast implementation continues between the locations of the network scenario, which allows the transfer of multimedia content between the locations. , and for this the routing protocols, Multicast, RTP, among others, are enabled. In this way, it is possible to configure the IPTV service plus the QoS Quality of Service