54,128 research outputs found

    Final-State Interactions in the Superscaling Analysis of Neutral-Current Quasielastic Neutrino Scattering

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    Effects of strong final-state interactions in the superscaling properties of neutral-current quasielastic neutrino cross sections are investigated using the Relativistic Impulse Approximation as guidance. First- and second-kind scaling are analyzed for neutrino beam energies ranging from 1 to 2 GeV for the cases of 12C, 16O and 40Ca. Different detection angles of the outgoing nucleon are considered in order to sample various nucleon energy regimes. Scaling of the second kind is shown to be very robust. Validity of first-kind scaling is found to be linked to the kinematics of the process. Superscaling still prevails even in the presence of very strong final-state interactions, provided that some kinematical restrains are kept, and the conditions under which superscaling can be applied to predict neutral-current quasielastic neutrino scattering are determined.Comment: 39 pages, 16 figures, accepted for publication in Phys. Rev.

    Gamma-Ray Bursts Black hole accretion disks as a site for the vp-process

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    We study proton rich nucleosynthesis in windlike outflows from gamma-ray bursts accretion disks with the aim to determine if such outflows are a site of the vp-process. The efficacy of this vp-process depends on thermodynamic and hydrodynamic factors. We discuss the importance of the entropy of the material, the outflow rate, the initial ejection point and accretion rate of the disk. In some cases the vp-process pushes the nucleosynthesis out to A~100 and produces light p-nuclei. However, even when these nuclei are not produced, neutrino induced interactions can significantly alter the abundance pattern and cannot be neglected.Comment: 9 pages, 16 figures, accepted for publication in Phys. Rev.

    Acrylamide Production Using Encapsulated Nitrile Hydratase from \u3cem\u3ePseudonocardia thermophila\u3c/em\u3e in a Sol–gel Matrix

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    The cobalt-type nitrile hydratase from Pseudonocardia thermophila JCM 3095 (PtNHase) was successfully encapsulated in tetramethyl orthosilicate sol–gel matrices to produce a PtNHase:sol–gel biomaterial. The PtNHase:sol–gel biomaterial catalyzed the conversion of 600 mM acrylonitrile to acrylamide in 60 min at 35 °C with a yields of \u3e90%. Treatment of the biomaterial with proteases confirmed that the catalytic activity is due to the encapsulated enzyme and not surface bound NHase. The biomaterial retained 50% of its activity after being used for a total of 13 consecutive reactions for the conversion of acrylonitrile to acrylamide. The thermostability and long-term storage of the PtNHase:sol–gel are substantially improved compared to the soluble NHase. Additionally, the biomaterial is significantly more stable at high concentrations of methanol (50% and 70%, v/v) as a co-solvent for the hydration of acrylonitrile than native PtNHase. These data indicate that PtNHase:sol–gel biomaterials can be used to develop new synthetic avenues involving nitriles as starting materials given that the conversion of the nitrile moiety to the corresponding amide occurs under mild temperature and pH conditions

    Degenerate Fermi Gas of 87^{87}Sr

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    We report quantum degeneracy in a gas of ultra-cold fermionic 87^{87}Sr atoms. By evaporatively cooling a mixture of spin states in an optical dipole trap for 10.5\,s, we obtain samples well into the degenerate regime with T/TF=0.26−.06+.05T/T_F=0.26^{+.05}_{-.06}. The main signature of degeneracy is a change in the momentum distribution as measured by time-of-flight imaging, and we also observe a decrease in evaporation efficiency below T/TF∼0.5T/T_F \sim 0.5.Comment: 4 pages, 3 figure

    Electron-phonon coupling in the two phonon mode ternary alloy Al0.25In0.75As/Ga0.25In0.75AsAl_{0.25}In_{0.75}As/Ga_{0.25}In_{0.75}As quantum well

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    We have investigated the infrared transmission of a two-dimensional (2DEG) electron gas confined in a Al0.25In0.75As/Ga0.25In0.75AsAl_{0.25}In_{0.75}As/Ga_{0.25}In_{0.75}As single quantum well in order to study the electron optical phonon interaction in a two phonon mode system. Infrared transmission experiments have been performed in both the perpendicular Faraday (PF) and tilted Faraday (TF) configurations for which the growth axis of the sample is tilted with respect to the incident light propagation direction and to the magnetic field direction. The experimental results lead to question the validity of the concept of polaron mass in a real material.Comment: 7 pages, 3 figure

    Bose-Einstein Condensation of 88^{88}Sr Through Sympathetic Cooling with 87^{87}Sr

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    We report Bose-Einstein condensation of 88^{88}Sr, which has a small, negative s-wave scattering length (a88=−2a_{88}=-2\,a0a_0). We overcome the poor evaporative cooling characteristics of this isotope by sympathetic cooling with 87^{87}Sr atoms. 87^{87}Sr is effective in this role in spite of the fact that it is a fermion because of the large ground state degeneracy arising from a nuclear spin of I=9/2I=9/2, which reduces the impact of Pauli blocking of collisions. We observe a limited number of atoms in the condensate (Nmax≈104N_{max}\approx 10^4) that is consistent with the value of a88a_{88} and the optical dipole trap parameters.Comment: 4 pages, 4 figure

    A Novel Low-Cost Sensor Prototype for Nocturia Monitoring in Older People

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    Indexación: Scopus.This work was supported in part by CORFO - CENS 16CTTS-66390 through the National Center on Health Information Systems, in part by the National Commission for Scientific and Technological Research (CONICYT) through the program STIC-AMSUD 17STIC-03: ‘‘e-MONITOR âĂŞ Chronic Disease: Ambient Assisted Living and vital teleMONOTORing for e-health,’’ FONDEF ID16I10449 ‘‘Sistema inteligente para la gestión y análisis de la dotación de camas en la red asistencial del sector público,’’ and MEC80170097 ‘‘Red de colaboración científica entre universidades nacionales e internacionales para la estructuración del doctorado y magister en informática médica en la Universidad de Valparaíso.’’ The work of V. H. C. de Albuquerque was supported by the Brazilian National Council for Research and Development (CNPq) under Grant #304315/2017-6.Nocturia is frequently defined as the necessity to get out of bed at least one time during the night to urinate, with each of these episodes being preceded and continued by sleep. Several studies suggest that an increase of nocturia is seen with the onset of age, occurring in around 70% of adults over the age of 70. Its appearance is associated with detrimental quality of life for those who present nocturia, since it leads to daytime sleepiness, cognitive dysfunction, among others. Currently, a voiding diary is necessary for nocturia assessment; these are prone to bias due to their inherent subjectivity. In this paper, we present the design of a low-cost device that automatically detects micturition events. The device obtained 73% in sensibility and 81% in specificity; these results show that systems such as the proposed one can be a valuable tool for the medical team when evaluating nocturia. © 2013 IEEE.https://ieeexplore.ieee.org/document/845445

    A novel monitoring system for fall detection in older people

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    Indexación: Scopus.This work was supported in part by CORFO - CENS 16CTTS-66390 through the National Center on Health Information Systems, in part by the National Commission for Scientific and Technological Research (CONICYT) through the Program STIC-AMSUD 17STIC-03: ‘‘MONITORing for ehealth," FONDEF ID16I10449 ‘‘Sistema inteligente para la gestión y análisis de la dotación de camas en la red asistencial del sector público’’, and in part by MEC80170097 ‘‘Red de colaboración científica entre universidades nacionales e internacionales para la estructuración del doctorado y magister en informática médica en la Universidad de Valparaíso’’. The work of V. H. C. De Albuquerque was supported by the Brazilian National Council for Research and Development (CNPq), under Grant 304315/2017-6.Each year, more than 30% of people over 65 years-old suffer some fall. Unfortunately, this can generate physical and psychological damage, especially if they live alone and they are unable to get help. In this field, several studies have been performed aiming to alert potential falls of the older people by using different types of sensors and algorithms. In this paper, we present a novel non-invasive monitoring system for fall detection in older people who live alone. Our proposal is using very-low-resolution thermal sensors for classifying a fall and then alerting to the care staff. Also, we analyze the performance of three recurrent neural networks for fall detections: Long short-term memory (LSTM), gated recurrent unit, and Bi-LSTM. As many learning algorithms, we have performed a training phase using different test subjects. After several tests, we can observe that the Bi-LSTM approach overcome the others techniques reaching a 93% of accuracy in fall detection. We believe that the bidirectional way of the Bi-LSTM algorithm gives excellent results because the use of their data is influenced by prior and new information, which compares to LSTM and GRU. Information obtained using this system did not compromise the user's privacy, which constitutes an additional advantage of this alternative. © 2013 IEEE.https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=842305

    Frohlich mass in GaAs-based structures

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    The Frohlich interaction is one of the main electron-phonon intrinsic interactions in polar materials originating from the coupling of one itinerant electron with the macroscopic electric field generated by any longitudinal optical (LO) phonon. Infra-red magneto-absorption measurements of doped GaAs quantum wells structures have been carried out in order to test the concept of Frohlich interaction and polaron mass in such systems. These new experimental results lead to question the validity of this concept in a real system.Comment: 4 pages, 3 figure
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