297 research outputs found

    Unexpected Occurrence of Mesospheric Frontal Gravity Wave Events Over the South Pole (90 degrees S)

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    Since 2010, Utah State University has operated an infrared Advanced Mesospheric Temperature Mapper at the Amundsen–Scott South Pole station to investigate the upper atmosphere dynamics and temperature deep within the vortex. A surprising number of “frontal” gravity wave events (86) were recorded in the mesospheric OH(3,1) band intensity and rotational temperature images (typical altitude of ~87 km) during four austral winters (2012–2015). These events are gravity waves (GWs) characterized by a sharp leading wave front followed by a quasi-monochromatic wave train that grows with time. A particular subset of frontal gravity wave events has been identified in the past (Dewan & Picard, 1998) as “bores.” These are usually associated with wave ducting within stable mesospheric inversion layers, which allow them to propagate over very large distances. They have been observed on numerous occasions from low-latitude and midlatitude sites, but to date, very few have been reported at high latitudes. This study provides new analyses of the characteristics of frontal events at high latitudes and shows that most of them are likely ducted. The occurrence of these frontal GW events over this isolated region strongly supports the existence of horizontally extensive mesospheric thermal inversion layers over Antarctica, leading to regions of enhanced stability necessary for GW trapping and ducting

    Agronomic Potential and Nutritive Value of Promising \u3ci\u3eLeucaena\u3c/i\u3e Species in the Yucatan Peninsula

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    Two experiments were carried out in order to evaluate the agronomic potential, the nutritive value and the tolerance to psyllid (Heteropsilla cubana) of nine Leucaena species. A randomized block design with four repetitions was used. There were significant (P\u3c 0.01) differences on dry matter production (i.e. leaf and twigs yield ). L. collinsii showed the most promising result, which could be related to its high psyllid tolerance. In a second experiment, the preference indices of Leucaena species was assessed with sixteen male pelibuey sheep in a cafeteria trial. There were significant (P\u3c 0.0001) differences among Leucaena species. L. esculenta paniculata was the species most preferred . There was no relationship between chemical composition (i.e. ADF, NDF, and polyphenols) and preference and psyllid tolerance

    Reestructura de los espacios de talleres holísticos en el albergue CN A.C.

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    El contenido de este documento incluye el trabajo elaborado durante el semestre de otoño 2018, en el cual desde la perspectiva arquitectónica y psicológica se hizo el análisis de los talleres del departamento de C.R.E. donde a partir de la reubicación de los salones para los talleres, el objetivo principal era crear un espacio que permitiera el desarrollo integral de los residentes del albergue la Ciudad de los Niños. Esto aunado a la implementación de los nuevos talleres holísticos, donde ahora con esta modalidad busca que cada sesión sea planeada por los psicólogos desde una perspectiva en la que se trabajen las emociones por medio de un enfoque de Arteterapia, además de esto la intervención en los salones de talleres desde la visión arquitectónica, para propiciar un mejor espacio donde se puedan desarrollar este tipo de actividades, en espacios apropiados, dignos y motivadores de la actividad de residentes y formadores- talleristas.ITESO, A.C.ITESO- ALBERGUE CIUDAD DE LOS NIÑO

    Electronic States in Diffused Quantum Wells

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    In the present study we calculate the energy values and the spatial distributions of the bound electronic states in some diffused quantum wells. The calculations are performed within the virtual crystal approximation, sp3ssp^3 s^* spin dependent empirical tight-binding model and the surface Green function matching method. A good agreement is found between our results and experimental data obtained for AlGaAs/GaAs quantum wells with thermally induced changes in the profile at the interfaces. Our calculations show that for diffusion lengths LD=20÷100L_{D}=20\div100 {\AA} the transition (C3-HH3) is not sensitive to the diffusion length, but the transitions (C1-HH1), (C1-LH1), (C2-HH2) and (C2-LH2) display large "blue shifts" as L_{D} increases. For diffusion lengths LD=0÷20L_{D}=0\div20 {\AA} the transitions (C1-HH1) and (C1-LH1) are less sensitive to the L_{D} changes than the (C3-HH3) transition. The observed dependence is explained in terms of the bound states spatial distributions.Comment: ReVTeX file, 7pp., no macros, 4 figures available on the reques

    An Army of Me: Sockpuppets in Online Discussion Communities

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    In online discussion communities, users can interact and share information and opinions on a wide variety of topics. However, some users may create multiple identities, or sockpuppets, and engage in undesired behavior by deceiving others or manipulating discussions. In this work, we study sockpuppetry across nine discussion communities, and show that sockpuppets differ from ordinary users in terms of their posting behavior, linguistic traits, as well as social network structure. Sockpuppets tend to start fewer discussions, write shorter posts, use more personal pronouns such as "I", and have more clustered ego-networks. Further, pairs of sockpuppets controlled by the same individual are more likely to interact on the same discussion at the same time than pairs of ordinary users. Our analysis suggests a taxonomy of deceptive behavior in discussion communities. Pairs of sockpuppets can vary in their deceptiveness, i.e., whether they pretend to be different users, or their supportiveness, i.e., if they support arguments of other sockpuppets controlled by the same user. We apply these findings to a series of prediction tasks, notably, to identify whether a pair of accounts belongs to the same underlying user or not. Altogether, this work presents a data-driven view of deception in online discussion communities and paves the way towards the automatic detection of sockpuppets.Comment: 26th International World Wide Web conference 2017 (WWW 2017

    Stable Thermally-Modulated Nanodroplet Ultrasound Contrast Agents

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    Liquid perfluorocarbon-based nanodroplets are stable enough to be used in extravascular imaging, but provide limited contrast enhancement due to their small size, incompressible core, and small acoustic impedance mismatch with biological fluids. Here we show a novel approach to overcoming this limitation by using a heating–cooling cycle, which we will refer to as thermal modulation (TM), to induce echogenicity of otherwise stable but poorly echogenic nanodroplets without triggering a transient phase shift. We apply thermal modulation to high-boiling point tetradecafluorohexane (TDFH) nanodroplets stabilized with a bovine serum albumin (BSA) shell. BSA-TDFH nanodroplets with an average diameter under 300 nanometers showed an 11.9 ± 5.4 mean fold increase in echogenicity on the B-mode and a 13.9 ± 6.9 increase on the nonlinear contrast (NLC) mode after thermal modulation. Once activated, the particles maintained their enhanced echogenicity (p \u3c 0.001) for at least 13 h while retaining their nanoscale size. Our data indicate that thermally modulated nanodroplets can potentially serve as theranostic agents or sensors for various applications of contrast-enhanced ultrasound

    Long-term efficacy and safety results of taliglucerase alfa through 5years in adult treatment-naïve patients with Gaucher disease

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    Taliglucerase alfa, the first available plant cell-expressed recombinant therapeutic protein, is an enzyme replacement therapy approved for Gaucher disease (GD). PB-06-001, a pivotal phase 3, multicenter, randomized, double-blind, parallel-dose study investigated taliglucerase alfa 30 or 60U/kg every other week through 9months in treatment-naïve adults with GD; 30-month extension study PB-06-003 followed. Patients completing PB-06-001 and PB-06-003 could continue treatment in PB-06-007. Nineteen patients enrolled in PB-06-007 (30U/kg, n=8; 60U/kg, n=9; dose adjusted, n=2); 17 completed 5 total years of treatment. In these 3 groups, respectively, taliglucerase alfa resulted in mean decreases in spleen volume (-8.7, -6.9, -12.4 multiples of normal), liver volume (-0.6, -0.4, -0.5 multiples of normal), chitotriosidase activity (-83.1%, -93.4%, -87.9%), and chemokine (CC motif) ligand 18 concentration (-66.7%, -83.3%, -78.9%), as well as mean increases in hemoglobin concentration (+2.1, +2.1, +1.8mg/dL) and platelet count (+31,871, +106,800, +34,000/mm3). The most common adverse events were nasopharyngitis and arthralgia. Most adverse events were mild/moderate; no serious adverse events were considered treatment-related. These results demonstrate continued improvement of disease parameters during 5years of taliglucerase alfa therapy in 17 treatment-naive patients with no new safety concerns, extending the taliglucerase alfa clinical efficacy and safety dataset. This study was registered at www.clinicaltrials.gov as NCT01422187

    Magnetooptical effects in quantum wells irradiated with light pulses

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    The method of detection and investigation of the magnetopolaron effect in the semiconductor quantum wells (QW) in a strong magnetic field, based on pulse light irradiation and measuring the reflected and transmitted pulses, has been proposed. It has been shown that a beating amplitude on the frequencies, corresponding to the magnetopolaron energy level splitting, depends strongly from the exciting pulse width. The existence of the time points of the total reflection and total transparency has been predicted. The high orders of the perturbation theory on electron-electromagnetic field interaction have been taken into account.Comment: 5 pages, 5 figures with captions, corrected typos, figures are reedeted to improve their quality in accordance with the Referee requirement; Phys. Rev. B, Brief Reports, submitted for publicatio

    Computer science approach to the stellar fabric of violent starforming regions in AGN

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    In order to analyse the large numbers of Seyfert galaxy spectra available at present, we are testing new techniques to derive their physical parameters fastly and accurately. We present an experiment on such a new technique to segregate old and young stellar populations in galactic spectra using machine learning methods. We used an ensemble of classifiers, each classifier in the ensemble specializes in young or old populations and was trained with locally weighted regression and tested using ten-fold cross-validation. Since the relevant information concentrates in certain regions of the spectra we used the method of sequential floating backward selection offline for feature selection. Very interestingly, the application to Seyfert galaxies proved that this technique is very insensitive to the dilution by the Active Galactic Nucleus (AGN) continuum. Comparing with exhaustive search we concluded that both methods are similar in terms of accuracy but the machine learning method is faster by about two orders of magnitude.Comment: 4 pages, 1 figure, Contribution to IAU Symp. 222, The interplay among Black Holes, Stars and ISM in Galactic Nuclei, Gramado, Brazil, 200
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