3,505 research outputs found
Deterministic Relay Networks with State Information
Motivated by fading channels and erasure channels, the problem of reliable
communication over deterministic relay networks is studied, in which relay
nodes receive a function of the incoming signals and a random network state. An
achievable rate is characterized for the case in which destination nodes have
full knowledge of the state information. If the relay nodes receive a linear
function of the incoming signals and the state in a finite field, then the
achievable rate is shown to be optimal, meeting the cut-set upper bound on the
capacity. This result generalizes on a unified framework the work of
Avestimehr, Diggavi, and Tse on the deterministic networks with state
dependency, the work of Dana, Gowaikar, Palanki, Hassibi, and Effros on linear
erasure networks with interference, and the work of Smith and Vishwanath on
linear erasure networks with broadcast.Comment: 5 pages, to appear in proc. IEEE ISIT, June 200
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Spatiomechanical Modulation of EphB4-Ephrin-B2 Signaling in Neural Stem Cell Differentiation.
Interactions between EphB4 receptor tyrosine kinases and their membrane-bound ephrin-B2 ligands on apposed cells play a regulatory role in neural stem cell differentiation. With both receptor and ligand constrained to move within the membranes of their respective cells, this signaling system inevitably experiences spatial confinement and mechanical forces in conjunction with receptor-ligand binding. In this study, we reconstitute the EphB4-ephrin-B2 juxtacrine signaling geometry using a supported-lipid-bilayer system presenting laterally mobile and monomeric ephrin-B2 ligands to live neural stem cells. This experimental platform successfully reconstitutes EphB4-ephrin-B2 binding, lateral clustering, downstream signaling activation, and neuronal differentiation, all in a configuration that preserves the spatiomechanical aspects of the natural juxtacrine signaling geometry. Additionally, the supported bilayer system allows control of lateral movement and clustering of the receptor-ligand complexes through patterns of physical barriers to lateral diffusion fabricated onto the underlying substrate. The results from this study reveal a distinct spatiomechanical effect on the ability of EphB4-ephrin-B2 signaling to induce neuronal differentiation. These observations parallel similar studies of the EphA2-ephrin-A1 system in a very different biological context, suggesting that such spatiomechanical regulation may be a common feature of Eph-ephrin signaling
A new analysis technique to measure the W Production Charge Asymmetry at the Tevatron
We propose an analysis technique to directly measure W production charge
asymmetry from W leptonic decay events at the Tevatron and show the feasibility
for new analysis method using Monte Carlo simulations.Comment: 5 pages, 5 figures, to be published in PRD rapid communication
Bocavirus Infection in Hospitalized Children, South Korea
This study presents the first evidence of human bocavirus infection in South Korean children. The virus was detected in 27 (8.0%) of 336 tested specimens, including 17 (7.5%) of 225 virus-negative specimens, collected from children with acute lower respiratory tract infection
The Clinical Usefulness of 18F-FDG PET/CT for the Evaluation of Lymph Node Metastasis in Periorbital Malignancies
PURPOSE: Surgical treatment of malignancies in the oral cavity and subsequent radiotherapy often result in an oral condition unfavorable for prosthodontic rehabilitation. This study assessed the quality of life related to oral function in edentulous head and neck cancer patients following oncology treatment of malignancies in the lower region of the oral cavity. MATERIALS AND METHODS: Patients treated between 1990 and 2000 with surgery and radiotherapy for a squamous cell carcinoma in the oral cavity who were edentulous in the mandible and had been treated with a conventional, non-implant-retained denture received an invitation for a clinical check-up (clinical assessment, questionnaires regarding oral function and quality of life). RESULTS: Sixty-seven of the 84 patients who fulfilled the inclusion criteria were willing to participate in the study. The mean irradiation dosage that these patients had received in the oral region was 61.8 +/- 5.4 Gy. Half of the patients (n=33) were not very satisfied with their prostheses; they wore their mandibular prostheses at most a few hours per day. It was concluded from the clinical assessment that two thirds of the patients (n 4) could benefit from an implant-retained mandibular denture. Analyses of the questionnaires revealed no significant associations between functional assessments, quality of life, and parameters such as size of the primary tumor, location of the primary tumor, and different treatment regimes. Despite cancer treatment, the patients reported a rather good general quality of life. CONCLUSIONS: Sequelae resulting from radiotherapy probably dominate oral function and quality of life after oncology treatment. In two thirds of the patients, improvement of oral function and related quality of life would be expected with the use of an implant-retained mandibular denture
Limits of Binaries That Can Be Characterized by Gravitational Microlensing
Due to the high efficiency of planet detections, current microlensing planet
searches focus on high-magnification events. High-magnification events are
sensitive to remote binary companions as well and thus a sample of
wide-separation binaries are expected to be collected as a byproduct. In this
paper, we show that characterizing binaries for a portion of this sample will
be difficult due to the degeneracy of the binary-lensing parameters. This
degeneracy arises because the perturbation induced by the binary companion is
well approximated by the Chang-Refsdal lensing for binaries with separations
greater than a certain limit. For binaries composed of equal mass lenses, we
find that the lens binarity can be noticed up to the separations of
times of the Einstein radius corresponding to the mass of each lens. Among
these binaries, however, we find that the lensing parameters can be determined
only for a portion of binaries with separations less than times of
the Einstein radius.Comment: 5 pages, 3 figures, 1 tabl
Detection Probability of a Low-Mass Planet for Triple Lens Events: Implication of Properties of Binary-Lens Superposition
In view of the assumption that any planetary system is likely to be composed
of more than one planet, and the multiple planet system with a large mass
planet has more chance of detailed follow-up observations, the multiple planet
system may be an efficient way to search for sub-Jovian planets. We compare the
magnification pattern of the triple lens system with that of a best-fitted
binary system composed of a star and a Jovian mass planet, and check the
probability in detecting the low-mass secondary planet whose signature will be
superposed on that of the primary Jovian mass planet. Detection probabilities
of the low-mass planet in the triple lens system are quite similar to the
probability in detecting such a low-mass planet in a binary system with a star
and only a low-mass planet, which shows that the signature of a low-mass planet
can be effectively detected even when it is concurrent with the signature of
the more massive planet, implying that the binary superposition approximation
works over a relatively broad range of planet mass ratio and separations, and
the inaccuracies thereof do not significantly affect the detection probability
of the lower mass secondary planet. Since the signature of the Jovian mass
planet will be larger and lasts longer, thereby warranting more intensive
follow-up observations, the actual detection rate of the low-mass planet in a
triple system with a Jovian mass can be significantly higher than that in a
binary system with a low-mass planet only. We conclude that it may be
worthwhile to develop an efficient algorithm to search for `super-Earth'
planets in the paradigm of the triple lens model for high-magnification
microlensing events.Comment: 10 pages, 5 figures, accepted by MNRA
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