8,062 research outputs found
Space Shuttle/TDRSS communication and tracking systems analysis
In order to evaluate the technical and operational problem areas and provide a recommendation, the enhancements to the Tracking and Data Delay Satellite System (TDRSS) and Shuttle must be evaluated through simulation and analysis. These enhancement techniques must first be characterized, then modeled mathematically, and finally updated into LinCsim (analytical simulation package). The LinCsim package can then be used as an evaluation tool. Three areas of potential enhancements were identified: shuttle payload accommodations, TDRSS SSA and KSA services, and shuttle tracking system and navigation sensors. Recommendations for each area were discussed
The Discovery of an X-ray/UV Stellar Flare from the Late-K/Early-M Dwarf LMC 335
We report the discovery of an X-ray/UV stellar flare from the source LMC 335,
captured by XMM-Newton in the field of the Large Magellanic Cloud. The flare
event was recorded continuously in X-ray for its first 10 hours from the
precursor to the late decay phases. The observed fluxes increased by more than
two orders of magnitude at its peak in X-ray and at least one in the UV as
compared to quiescence. The peak 0.1-7.0 keV X-ray flux is derived from the
two-temperature APEC model to be ~(8.4 +/- 0.6) x 10^-12 erg cm-2 s-1.
Combining astrometric information from multiple X-ray observations in the
quiescent and flare states, we identify the NIR counterpart of LMC 335 as the
2MASS source J05414534-6921512. The NIR color relations and spectroscopic
parallax characterize the source as a Galactic K7-M4 dwarf at a foreground
distance of (100 - 264) pc, implying a total energy output of the entire event
of ~(0.4 - 2.9) x 10^35 erg. This report comprises detailed analyses of this
late-K / early-M dwarf flare event that has the longest time coverage yet
reported in the literature. The flare decay can be modeled with two exponential
components with timescales of ~28 min and ~4 hours, with a single component
decay firmly ruled out. The X-ray spectra during flare can be described by two
components, a dominant high temperature component of ~40-60MK and a low
temperature component of ~10MK, with a flare loop length of about 1.1-1.3
stellar radius.Comment: 35 pages, 6 figures, 5 tables, accepted for publication in Ap
Nuclear isotope thermometry
We discuss different aspects which could influence temperatures deduced from
experimental isotopic yields in the multifragmentation process. It is shown
that fluctuations due to the finite size of the system and distortions due to
the decay of hot primary fragments conspire to blur the temperature
determination in multifragmentation reactions. These facts suggest that caloric
curves obtained through isotope thermometers, which were taken as evidence for
a first-order phase transition in nuclear matter, should be investigated very
carefully.Comment: 9 pages, 7 figure
A blockchain-IoT platform for the smart pallet pooling management
Pallet management as a backbone of logistics and supply chain activities is essential to supply chain parties, while a number of regulations, standards and operational constraints are considered in daily operations. In recent years, pallet pooling has been unconventionally advocated to manage pallets in a closed-loop system to enhance the sustainability and operational effectiveness, but pitfalls in terms of service reliability, quality compliance and pallet limitation when using a single service provider may occur. Therefore, this study incorporates a decentralisation mechanism into the pallet management to formulate a technological eco-system for pallet pooling, namely Pallet as a Service (PalletaaS), raised by the foundation of consortium blockchain and Internet of things (IoT). Consortium blockchain is regarded as the blockchain 3.0 to facilitate more industrial applications, except cryptocurrency, and the synergy of integrating a consortium blockchain and IoT is thus investigated. The corresponding layered architecture is proposed to structure the system deployment in the industry, in which the location-inventory-routing problem for pallet pooling is formulated. To demonstrate the values of this study, a case analysis to illustrate the human–computer interaction and pallet pooling operations is conducted. Overall, this study standardises the decentralised pallet management in the closed-loop mechanism, resulting in a constructive impact to sustainable development in the logistics industry
CD4+ T-cell responses to Epstein-Barr virus nuclear antigen EBNA1 in Chinese populations are highly focused on novel C-terminal domain-derived epitopes
Epstein-Barr virus nuclear antigen EBNA1, the one viral protein uniformly expressed in nasopharyngeal carcinoma (NPC), represents a prime target for T-cell-based immunotherapy. However, little is known about the EBNA1 epitopes, particularly CD4 epitopes, presented by HLA alleles in Chinese people, the group at highest risk for NPC. We analyzed the CD4 T-cell responses to EBNA1 in 78 healthy Chinese donors and found marked focusing on a small number of epitopes in the EBNA1 C-terminal region, including a DP5- restricted epitope that was recognized by almost half of the donors tested and elicited responses able to recognize EBNA1-expressing, DP5-positive target cells
On Determining Dead Layer and Detector Thicknesses for a Position-Sensitive Silicon Detector
In this work, two particular properties of the position-sensitive, thick
silicon detectors (known as the "E" detectors) in the High Resolution Array
(HiRA) are investigated: the thickness of the dead layer on the front of the
detector, and the overall thickness of the detector itself. The dead layer
thickness for each E detector in HiRA is extracted using a measurement of alpha
particles emitted from a Pb pin source placed close to the detector
surface. This procedure also allows for energy calibrations of the E detectors,
which are otherwise inaccessible for alpha source calibration as each one is
sandwiched between two other detectors. The E detector thickness is obtained
from a combination of elastically scattered protons and an energy-loss
calculation method. Results from these analyses agree with values provided by
the manufacturer.Comment: Accepted for publication in Nuclear Instruments and Methods in
Physics Researc
Positive Identity as a Positive Youth Development Construct: A Conceptual Review
Identity is a core construct in psychology because it refers to how a person addresses issues dealing with who that person is. Important theorists studying the concept of identity, like Erikson, Marcia, and Higgins, assert that identity is organized,is learned, and is dynamic, and a subjective evaluation of an individual's identity has emotional consequences for that individual. Adolescents who can cultivate a clear and positive identity after their developmental struggles during adolescence often advance more smoothly into adulthood. This paper reviews literature on the nature and structure of identity and examines its importance on adolescent developmental outcomes. It traces significant determinants of identity and proposes strategies for cultivation of positive identity. Observations on current research gaps in the study of identity and future research directions will also be discussed
Bystander Position Taking in School Bullying: The Role of Positive Identity, Self-Efficacy, and Self-Determination
School bullying has become an explicit, burgeoning problem challenging the healthy development of children and adolescents in Hong Kong. Many bullying prevention and intervention programs focus on victims and bullies, with bystanders treated as either nonexistent or irrelevant. This paper asserts that bystanders actually play pivotal roles in deciding whether the bullying process and dynamics are benign or adversarial. Bystanders' own abilities and characteristics often influence how they respond to victims and bullies. “P.A.T.H.S. to Adulthood: A Jockey Club Youth Enhancement Scheme” (P.A.T.H.S. = Positive Adolescent Training through Holistic Social Programmes) is an evidence-based positive youth development program which shows that primary intervention programs have constructive impacts on junior secondary school students' beliefs and behavior. This paper asserts that intrapsychic qualities, namely identity, self-efficacy, and self-determination, greatly influence how bystanders react in school bullying situations. The paper also explains how classroom-based educational programs based on the P.A.T.H.S. model have been designed to help junior secondary school students strengthen these characteristics, so that they can be constructive bystanders when they encounter school bullying
Effect of isospin dependent cross-section on fragment production in the collision of charge asymmetric nuclei
To understand the role of isospin effects on fragmentation due to the
collisions of charge asymmetric nuclei, we have performed a complete
systematical study using isospin dependent quantum molecular dynamics model.
Here simulations have been carried out for , where n
varies from 47 to 59 and for , where m varies from 14
to 23. Our study shows that isospin dependent cross-section shows its influence
on fragmentation in the collision of neutron rich nuclei
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