98 research outputs found
Heat Conduction and Magnetic Phase Behavior in Electron-Doped Ca_{1-x} La_x MnO_3(0 <= x <= 0.2)
Measurements of thermal conductivity (kappa) vs temperature are reported for
a series of Ca_{1-x} La_x MnO_3(0 <= x <= 0.2) specimens. For the undoped
(x=0), G-type antiferromagnetic compound a large enhancement of kappa below the
Neel temperature (T_N ~ 125 K) indicates a strong coupling of heat-carrying
phonons to the spin system. This enhancement exhibits a nonmonotonic behavior
with increasing x and correlates remarkably well with the small ferromagnetic
component of the magnetization reported previously [Neumeier and Cohn, Phys.
Rev. B 61 14319 (2000).] Magnetoelastic polaron formation appears to underly
the behavior of kappa and the magnetization at x <= 0.02.Comment: submitted to PRB; 4 pp., 4 Fig.'s, RevTex
Idling Magnetic White Dwarf in the Synchronizing Polar BY Cam. The Noah-2 Project
Results of a multi-color study of the variability of the magnetic cataclysmic
variable BY Cam are presented. The observations were obtained at the Korean
1.8m and Ukrainian 2.6m, 1.2m and 38-cm telescopes in 2003-2005, 56
observational runs cover 189 hours. The variations of the mean brightness in
different colors are correlated with a slope dR/dV=1.29(4), where the number in
brackets denotes the error estimates in the last digits. For individual runs,
this slope is much smaller ranging from 0.98(3) to 1.24(3), with a mean value
of 1.11(1). Near the maximum, the slope becomes smaller for some nights,
indicating more blue spectral energy distribution, whereas the night-to-night
variability has an infrared character. For the simultaneous UBVRI photometry,
the slopes increase with wavelength from dU/dR=0.23(1) to dI/dR=1.18(1). Such
wavelength dependence is opposite to that observed in non-magnetic cataclysmic
variables, in an agreement to the model of cyclotron emission. The principal
component analysis shows two (with a third at the limit of detection)
components of variablitity with different spectral energy distribution, which
possibly correspond to different regions of emission. The scalegram analysis
shows a highest peak corresponding to the 200-min spin variability, its quarter
and to the 30-min and 8-min QPOs. The amplitudes of all these components are
dependent on wavelength and luminosity state. The light curves were fitted by a
statistically optimal trigonometrical polynomial (up to 4-th order) to take
into account a 4-hump structure. The dependences of these parameters on the
phase of the beat period and on mean brightness are discussed. The amplitude of
spin variations increases with an increasing wavelength and with decreasing
brightnessComment: 30pages, 11figures, accepted in Cent.Eur.J.Phy
Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy
We review HB stars in a broad astrophysical context, including both variable
and non-variable stars. A reassessment of the Oosterhoff dichotomy is
presented, which provides unprecedented detail regarding its origin and
systematics. We show that the Oosterhoff dichotomy and the distribution of
globular clusters (GCs) in the HB morphology-metallicity plane both exclude,
with high statistical significance, the possibility that the Galactic halo may
have formed from the accretion of dwarf galaxies resembling present-day Milky
Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the
second-parameter problem is presented. A technique is proposed to estimate the
HB types of extragalactic GCs on the basis of integrated far-UV photometry. The
relationship between the absolute V magnitude of the HB at the RR Lyrae level
and metallicity, as obtained on the basis of trigonometric parallax
measurements for the star RR Lyrae, is also revisited, giving a distance
modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are
studied. Finally, the conductive opacities used in evolutionary calculations of
low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and
Space Scienc
Biotecnología y selección de la palma de aceite: la Palma Dorada del futuro
Los marcadores de ADN, la secuenciación con sistemas NGS, la manipulación genética y las tecnologías de cultivo in vitro, combinadas con la caracterización fenotípica de alta tecnología, ponen al alcance de los cultivadores las variedades que desearían cultivar sin que hubieran podido imaginar siquiera que fuese posible sembrarlas. Se espera que las variedades de palma de aceite sufran muchos cambios desde el día de hoy hasta el año 2050, por medio de una selección biotecnológica de las especies E. guineensis y E. oleifera. La productividad de la palma de aceite está ligada estrechamente a su potencial fisiológico. El determinismo genético completamente dilucidado de la morfología de la fertilidad del fruto permite que existan nuevas variedades que solo contengan pulpa, tales como las pisifera fértiles y tenera partenocárpicos. El bajo crecimiento del tallo y la voluminosidad reducida logran que las palmas se cultiven en menos hectáreas de tierra, lo cual genera una cosecha menos costosa. La reducción de la frecuencia de cosecha (tan baja como una vez al mes) será posible gracias al no desprendimiento de frutos. La baja actividad de lipasa en la pulpa de los frutos maduros garantizará la producción de un aceite de palma sin ácidos libres significativos en los racimos entregados a las plantas extractoras, lo cual asegurará la producción en campo sin incurrir en pérdidas económicas. Las variedades con hasta 90 % de ácido oleico entrarán al mercado y este novedoso aceite de palma “aceitunado” se venderá a precios marcadamente más competitivos para la mesa de la mayoría de las personas del mundo, destronando así al mercado privilegiado del aceite de oliva mediterráneo, de mayor costo. El imperio del cultivo de palma de aceite ha expandido sus territorios a lo largo de América del Sur gracias a las variedades interespecíficas resistentes a la enfermedad de la Pudrición del cogollo, a la vez que se preservan considerablemente la mayoría de los bosques naturales al convertir los grandes pastizales en palmares
Case Based Representation and Retrieval with Time Dependent Features
Abstract. The temporal dimension of the knowledge embedded in cases has often been neglected or oversimplified in Case Based Reasoning sys-tems. However, in several real world problems a case should capture the evolution of the observed phenomenon over time. To this end, we propose to represent temporal information at two levels: (1) at the case level, if some features describe parameters varying within a period of time (which corresponds to the case duration), and are therefore collected in the form of time series; (2) at the history level, if the evolution of the system can be reconstructed by retrieving temporally related cases. In this paper, we describe a framework for case representation and retrieval able to take into account the temporal dimension, and meant to be used in any time dependent domain. In particular, to support case retrieval, we provide an analysis of similarity-based time series retrieval techniques; to support history retrieval, we introduce possible ways to summarize the case content, together with the corresponding strategies for identifying similar instances in the knowledge base. A concrete ap-plication of our framework is represented by the system RHENE, which is briefly sketched here, and extensively described in [20].
Global Retinoblastoma Presentation and Analysis by National Income Level
Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4) were female. Most patients (n = 3685 84.7%) were from low-and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 62.8%), followed by strabismus (n = 429 10.2%) and proptosis (n = 309 7.4%). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 95% CI, 12.94-24.80, and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 95% CI, 4.30-7.68). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs. © 2020 American Medical Association. All rights reserved
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Acceptance test report, 241-SY-101 Flexible Receiver System, Phase 1 testing
This document summarizes the results of the Phase 1 acceptance test of the 241-SY-101 Flexible Receiver System (FRS). This acceptance test consisted of a pressure-decay/leak test of the containment bag to verify that the seams along the length of the bag had been adequately sealed. The sealing integrity of the FRS must be verified to ensure that the release of waste and aerosols will be minimized during the removal of the test mixer pump from Tank 241-SY-101. The FRS is one of six major components of the Equipment Removal System, which has been designed to retrieve, transport, and store the mixer pump. This acceptance test was performed at Lancs Industries in Kirkland, Washington on January 17, 1995. The bag temperature-compensated pressure loss of 575 Pa was below the acceptance criteria of 625 Pa and the test results were therefore found to be acceptable. The bag manufacturer estimates that 80--90% of the pressure loss is attributed to leakage around the bag inflation valve where the pressure gage was connected. A leak detector was applied over the entire bag during the pre-tests and no leakage was found. Furthermore, the leak rate corresponding to this pressure loss is very small when compared to the acceptable leak rate of the completely assembled FRS. The sealing integrity of the assembled FRS is verified in Phase 3 testing
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Acceptance test report, 241-SY-101 Flexible Receiver System, Phase 2 testing
This document summarizes the results of the Phase 2 acceptance test of the 241-SY-101 Flexible Receiver System (FRS). The FRS is one of six major components of the Equipment Removal System, which has been designed to retrieve, transport, and store the test mixer pump currently installed in Tank 241-SY-101. The purpose of this acceptance test is to verify the strength of the containment bag and bag bottom cinching mechanism. It is postulated that 68 gallons of waste could be trapped inside the pump internals. The bag must be capable of supporting this waste if it shakes loose and drains to the bottom of the bag after the bag bottom has been cinched closed. This acceptance test was performed at the Maintenance and Storage Facility (MASF) Facility in the 400 area on January 23, 1995. The bag assembly supported the weight of 920 kg (2,020 lbs) of water with no leakage or damage to the bag. This value meets the acceptance criteria of 910 kg of water and therefore the results were found to be acceptable. The maximum volume of liquid expected to be held up in the pump internals is 258 L (68 gallons), which corresponds to 410 kg. This test weight gives just over a safety factor of 2. The bag also supported a small shock load while it was filled with water when the crane hoisted the bag assembly up and down. Based on the strength rating of the bag components, the bag assembly should support 2--3 times the test weight of 910 kg
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Acceptance test report, 241-SY-101 Flexible Receiver System, Phase 3 testing
This document summarizes the results of the phase 3 acceptance test of the 241-SY-101 Flexible Receiver System (FRS). The purpose of this acceptance test is to verify the sealing integrity of the FRS to ensure that the release of waste and aerosols will be minimized during the removal of the test mixer pump from Tank 241-SY-101. The FRS is one of six major components of the Equipment Removal System, which has been designed to retrieve, transport, and store the mixer pump. This acceptance test was performed at the 306E Facility in the 300 area from January 10, 1995 to January 17, 1995. The Phase 3 test consisted of two parts. Part one was a water leak test of the seal between the blast shield and mock load distribution frame (LDF) to ensure that significant contamination of the pump pit and waste interaction with the aluminum impact-limiting material under the LDF are prevented during the pump removal operation. The second part of this acceptance test was an air leak test of the assembled flexible receiver system. The purpose of this test was to verify that the release of hazardous aerosols will be minimized if the tank dome pressure becomes slightly positive during the decontamination of the mixer pump
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