28,928 research outputs found
Energy Efficient User Association and Power Allocation in Millimeter Wave Based Ultra Dense Networks with Energy Harvesting Base Stations
Millimeter wave (mmWave) communication technologies have recently emerged as
an attractive solution to meet the exponentially increasing demand on mobile
data traffic. Moreover, ultra dense networks (UDNs) combined with mmWave
technology are expected to increase both energy efficiency and spectral
efficiency. In this paper, user association and power allocation in mmWave
based UDNs is considered with attention to load balance constraints, energy
harvesting by base stations, user quality of service requirements, energy
efficiency, and cross-tier interference limits. The joint user association and
power optimization problem is modeled as a mixed-integer programming problem,
which is then transformed into a convex optimization problem by relaxing the
user association indicator and solved by Lagrangian dual decomposition. An
iterative gradient user association and power allocation algorithm is proposed
and shown to converge rapidly to an optimal point. The complexity of the
proposed algorithm is analyzed and the effectiveness of the proposed scheme
compared with existing methods is verified by simulations.Comment: to appear, IEEE Journal on Selected Areas in Communications, 201
Eimeria tenella protein trafficking: differential regulation of secretion versus surface tethering during the life cycle
Eimeria spp. are intracellular parasites that have a major impact on poultry. Effective live vaccines are available and the development of reverse genetic technologies has raised the prospect of using Eimeria spp. as recombinant vectors to express additional immunoprotective antigens. To study the ability of Eimeria to secrete foreign antigens or display them on the surface of the sporozoite, transiently transfected populations of E. tenella expressing the fluorescent protein mCherry, linked to endogenous signal peptide (SP) and glycophosphatidylinositol-anchor (GPI) sequences, were examined. The SP from microneme protein EtMIC2 (SP2) allowed efficient trafficking of mCherry to cytoplasmic vesicles and following the C-terminal addition of a GPI-anchor (from surface antigen EtSAG1) mCherry was expressed on the sporozoite surface. In stable transgenic populations, mCherry fused to SP2 was secreted into the sporocyst cavity of the oocysts and after excystation, secretion was detected in culture supernatants but not into the parasitophorous vacuole after invasion. When the GPI was incorporated, mCherry was observed on the sporozites surface and in the supernatant of invading sporozoites. The proven secretion and surface exposure of mCherry suggests that antigen fusions with SP2 and GPI of EtSAG1 may be promising candidates to examine induction of protective immunity against heterologous pathogens
Astrophysical Constraints on Large Extra Dimensions
In the Kaluza-Klein (KK) scenario with n large extra dimensions where gravity
propagates in the 4+n dimensional bulk of spacetime while gauge and matter
fields are confined to a four dimensional subspace, the light graviton KK modes
can be produced in the Sun, red giants and supernovae. We study the energy-loss
rates through photon-photon annihilation, electron-positron annihilation,
gravi-Compton-Primakoff scattering, gravi-bremsstrahlung and nucleon-nucleon
bremsstrahlung, and derive lower limits to the string scale M_S. The most
stringent lower limit obtained from SN1987A leads to TeV
(2.1-9.2 TeV) for the case of two (three) large extra dimensions.Comment: 12 pages, 4 figures, 2 tables; minor corrections, references adde
Preliminary navigation accuracy analysis for the TDRSS Onboard Navigation System (TONS) experiment on EP/EUVE
A Tracking and Data Relay Satellite System (TDRSS) Onboard Navigation System (TONS) is currently being developed by NASA to provide a high accuracy autonomous navigation capability for users of TDRSS and its successor, the Advanced TDRSS (ATDRSS). The fully autonomous user onboard navigation system will support orbit determination, time determination, and frequency determination, based on observation of a continuously available, unscheduled navigation beacon signal. A TONS experiment will be performed in conjunction with the Explorer Platform (EP) Extreme Ultraviolet Explorer (EUVE) mission to flight quality TONS Block 1. An overview is presented of TONS and a preliminary analysis of the navigation accuracy anticipated for the TONS experiment. Descriptions of the TONS experiment and the associated navigation objectives, as well as a description of the onboard navigation algorithms, are provided. The accuracy of the selected algorithms is evaluated based on the processing of realistic simulated TDRSS one way forward link Doppler measurements. The analysis process is discussed and the associated navigation accuracy results are presented
Symplectic capacity and short periodic billiard trajectory
We prove that a bounded domain in with smooth boundary has a
periodic billiard trajectory with at most bounce times and of length less
than , where is a positive constant which depends only on
, and is the supremum of radius of balls in . This
result improves the result by C.Viterbo, which asserts that has a
periodic billiard trajectory of length less than C'_n \vol(\Omega)^{1/n}. To
prove this result, we study symplectic capacity of Liouville domains, which is
defined via symplectic homology.Comment: 32 pages, final version with minor modifications. Published online in
Mathematische Zeitschrif
Health Research Participants' Preferences for Receiving Research Results
BACKGROUND: Participants in health research studies typically express interest in receiving results from the studies in which they participate. However, participants’ preferences and experiences related to receiving results are not well understood. In general, existing studies have had relatively small sample sizes and typically address specific and often sensitive issues within targeted populations. METHODS: The present study used an online survey to explore attitudes and experiences of registrants in ResearchMatch, a large database of past, present, and potential health research participants. Survey respondents provided information related to whether or not they received research results from studies in which they participated, the methods used to communicate results, their satisfaction with results, and when and how they would like to receive research results from future studies. 70,699 ResearchMatch registrants were notified of the study’s topic. Of the 5,207 registrants who requested full information about the study, 3,381 respondents completed the survey. RESULTS: Approximately 33% of respondents with previous health research participation reported receiving results. Approximately half of respondents with previous research participation reported no opportunity to request results. However, almost all respondents said researchers should always or sometimes offer results to participants. Respondents expressed particular interest in results related to their (or a loved one's) health, as well as information about studies’ purposes and any medical advances based on the results. In general, respondents’ most preferred dissemination methods for results were email and website postings. The least desirable dissemination methods for results included Twitter, conference calls, and text messages. Across all results, we compare the responses of respondents with and without previous research participation experience, and those who have worked in research organizations vs. those who have not. Compared to respondents who have previous participation experience, a greater proportion of respondents with no participation experience indicated that results should always be shared with participants. Likewise, respondents with no participation experience placed higher importance on the receipt of each type of results information included in the survey. CONCLUSIONS: We present findings from a survey assessing attitudes and experiences of a broad sample of respondents that addresses gaps in knowledge related to participants’ preferences for receiving results. The study’s findings highlight the potential for inconsistency between respondents’ expressed preferences to receive specific types of results via specific methods and researchers’ unwillingness or inability to provide them. We present specific recommendations to shift the approach of new studies to investigate participants’ preferences for receiving research results
Thermal diffusion by Brownian motion induced fluid stress
The Ludwig-Soret effect, the migration of a species due to a temperature
gradient, has been extensively studied without a complete picture of its cause
emerging. Here we investigate the dynamics of DNA and spherical particles sub
jected to a thermal gradient using a combination of Brownian dynamics and the
lattice Boltzmann method. We observe that the DNA molecules will migrate to
colder regions of the channel, an observation also made in the experiments of
Duhr, et al[1]. In fact, the thermal diffusion coefficient found agrees
quantitatively with the experimental value. We also observe that the thermal
diffusion coefficient decreases as the radius of the studied spherical
particles increases. Furthermore, we observe that the thermal
fluctuations-fluid momentum flux coupling induces a gradient in the stress
which leads to thermal migration in both systems.Comment: 6 pages, 5 figue
SU(3)_LxU(1)_N Model for Right-Handed Neutrino Neutral Currents
A model based on the \mbox{SU(3)}_L\otimes \mbox{U(1)}_N gauge group, in
which neutrinos have right-handed neutral currents is considered. We argue that
in order to have a result consistent with low-energy one, the right-handed
neutrino component must be treated as correction instead of an equivalent spin
state.Comment: 6 pages, Latex, no figures, Accepted for publication in Phys. Rev.
A quantitative evaluation of metallic conduction in conjugated polymers
As the periodicity in crystalline materials creates the optimal condition for
electronic delocalization, one might expect that in partially crystalline
conjugated polymers delocalization is impeded by intergrain transport. However,
for the best conducting polymers this presumption fails. Delocalization is
obstructed by interchain rather than intergrain charge transfer and we propose
a model of weakly coupled disordered chains to describe the physics near the
metal-insulator transition. Our quantitative calculations match the outcome of
recent broad-band optical experiments and provide a consistent explanation of
metallic conduction in polymers.Comment: 4 pages incl. 3 figure
Bilepton contributions to the neutrinoless double beta decay in the economical 3-3-1 model
Possible contributions of the bilepton to the neutrinoless double beta
decay in the economical 3-3-1 model are discussed. We
show that the decay in this model is due to both
sources--Majorana and Dirac neutrino masses. If
the mixing angle between charged gauge bosons, the standard model and
bilepton , is in range of the ratio of neutrino masses , both the Majorana and Dirac masses simultaneously give
contributions dominant to the decay. As results, constraints on the bilepton
mass are also given.Comment: 9 pages, 6 figure
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