1,286 research outputs found
Seamless Vertical Handover in WiFi and WiMAX Networks using RSS and Motion Detection: An Investigation
In this paper, we propose a decision making algorithm for seamless vertical handover between WiFi hotspots and an overlay WiMAX network. The inputs to the algorithm are the WiFi received signal strength (RSS) and estimated end-to-end TCP handover latency. Simulation of the algorithm using Matlab® reveals that the distance from the WiFi reception boundary at which handover must be initiated if it is to be seamless increases with both end-to-end TCP/IP handover latency and the speed of the mobile terminal towards or away from the WiFi access point. We conclude that RSS-based seamless handovers need to be augmented with network layer information if they are to be optimal
The flower mites of Trinidad III: The genus Rhinoseius (Acari: Ascidae)
http://deepblue.lib.umich.edu/bitstream/2027.42/56428/1/MP184.pd
A Software Radio Design Approach for Heterogeneous Wireless Access Protocol Transceivers
A study on the design of heterogeneous transceivers using the software radio approach is presented. The objective of the study is to extend the research on software radio towards the design of multi-protocol transceivers which can communicate between two or more heterogeneous wireless access technologies. A critical overview of some of the current multi- protocol software radio devices is presented. This is then followed by a proposal for a dual band WiFi/WiMAX transceiver based on software radio techniques. This design incorporates a multiband antenna as well as an RF WiFi/WiMAX mode switch which uses the WiFi received signal strength (RSS) to perform handover between the underlying WiFi and WiMAX networks
Mutual information harvested by uniformly accelerated particle detectors
We investigate the mutual information harvesting protocol for two uniformly
accelerated particle detectors. We numerically show that, while a single
detector responds as if it is immersed in a thermal bath, the quantum mutual
information between two accelerating detectors behaves differently than that of
two inertial detectors in a thermal bath. This is due to the fact that while
the Wightman function along the trajectory of a single uniformly accelerating
detector is the same as that of as a detector in a thermal bath, a pair of
detectors in the same respective cases will have different Wightman functions.Comment: 9 pages, 4 figure
Correlation harvesting between particle detectors in uniform motion
We investigate the correlation harvesting protocol using two Unruh-DeWitt
particle detectors moving along four classes of uniformly accelerated
trajectories categorized by Letaw: linear, catenary, cusped, and circular
motions. For each trajectory, two types of configurations are carried out: one
possesses a stationary (time-translation invariant) Wightman function and the
other is nonstationary. We find that detectors undergoing linear, catenary, and
cusped motions gain fewer correlations in the nonstationary configurations
compared to those in stationary configurations. Detectors in circular motion
have similar behavior in both configurations. We discuss the relative
suppression of correlation harvesting due to high acceleration for each case.
Remarkably we find that under certain circumstances detectors in both linear
and circular states of motion can harvest genuine (non-communication assisted)
entanglement even though they are in causal contact.Comment: 16 pages, 7 figure
Three Dimensional Polarimetric Neutron Tomography of Magnetic Fields
Through the use of Time-of-Flight Three Dimensional Polarimetric Neutron
Tomography (ToF 3DPNT) we have for the first time successfully demonstrated a
technique capable of measuring and reconstructing three dimensional magnetic
field strengths and directions unobtrusively and non-destructively with the
potential to probe the interior of bulk samples which is not amenable
otherwise.
Using a pioneering polarimetric set-up for ToF neutron instrumentation in
combination with a newly developed tailored reconstruction algorithm, the
magnetic field generated by a current carrying solenoid has been measured and
reconstructed, thereby providing the proof-of-principle of a technique able to
reveal hitherto unobtainable information on the magnetic fields in the bulk of
materials and devices, due to a high degree of penetration into many materials,
including metals, and the sensitivity of neutron polarisation to magnetic
fields. The technique puts the potential of the ToF time structure of pulsed
neutron sources to full use in order to optimise the recorded information
quality and reduce measurement time.Comment: 12 pages, 4 figure
Alveolar macrophages lack CCR2 expression and do not migrate to CCL2
Background: The recruitment of mononuclear cells has important implications for tissue
inflammation. Previous studies demonstrated enhanced CCR1 and CCR5 expression and
decreased CCR2 expression during in vitro monocyte to macrophage differentiation. To date, no
study examined the in vivo differences in chemokine receptor expression between human
peripheral blood monocytes and alveolar macrophages.
Methods: We examined the expression of these receptors in human peripheral blood monocytes
and alveolar macrophages using microarray analysis, reverse-transcriptase PCR, flow cytometry
and migration analyses.
Results: In contrast to peripheral blood monocytes, alveolar macrophages did not express the
CCL2 receptor, CCR2, and did not migrate toward CCL2. In contrast, monocytes and freshly
isolated resident alveolar macrophages both migrated towards CCL3. However, up to 6-fold more
monocytes migrated toward equivalent concentrations of CCL3 than did alveolar macrophages
from the same donor. While peripheral blood monocytes expressed the CCL3 receptor, CCR1,
alveolar macrophages expressed the alternate CCL3 receptor, CCR5. The addition of anti-CCR5
blocking antibodies completely abrogated CCL3-induced migration in alveolar macrophages, but
did not affect the migration of peripheral blood monocytes.
Conclusion: These data support the specificity of CCL2 to selectively drive monocyte, but not
alveolar macrophage recruitment to the lung and CCR5 as the primary macrophage receptor for
CCL3
Prevalence of and factors associated with anxiety and depression among women in a lower middle class semi-urban community of Karachi, Pakistan
Objective: To study the prevalence of, and factors associated with anxiety and depression among women.Design: A cross sectional survey.SETTING: A lower middle class semi-urban community of Karachi, Pakistan.PARTICIPANTS: A total of 1218 women between the ages of 18-50 years.METHODOLOGY: Systematically every third household was identified from which a woman was randomly selected. The Aga Khan University Anxiety and Depression Scale and a socio-demographic questionnaire were administered verbally by trained interviewers for assessing the prevalence of, and associated factors for anxiety and depression.Results: A prevalence of 30% was found. Increasing age, lack of education and verbal abuse were the associated factors found to have an independent relationship.CONCLUSION: Providing education and reducing domestic abuse could lead to decrease in the prevalence of anxiety and depression in women
A mechanistic target of rapamycin complex 1/2 (mTORC1)/V-Akt murine thymoma viral oncogene homolog 1 (AKT1)/cathepsin H axis controls filaggrin expression and processing in skin, a novel mechanism for skin barrier disruption in patients with atopic dermatitis
BACKGROUND: Filaggrin, encoded by the FLG gene, is an important component of the skin’s barrier to the external environment and genetic defects in FLG strongly associate with Atopic Dermatitis (AD). However, not all AD patients have FLG mutations. OBJECTIVE: We hypothesised that these patients may possess other defects in filaggrin expression and processing, contributing to barrier disruption and AD, and therefore present novel therapeutic targets for this disease. RESULTS: We describe the relationship between the mTORC1 protein subunit RAPTOR, the serine/threonine kinase AKT1 and the protease cathepsin H, for which we establish a role in filaggrin expression and processing. Increased RAPTOR levels correlated with decreased filaggrin expression in AD. In keratinocyte cell culture, RAPTOR up-regulation or AKT1 shRNA knockdown reduced the expression of the protease cathepsin H. Skin of cathepsin H-deficient mice and CTSH shRNA knockdown keratinocytes showed reduced filaggrin processing and the mouse showed both impaired skin barrier function and a mild proinflammatory phenotype. CONCLUSION: Our findings highlight a novel, potentially treatable, signalling axis controlling filaggrin expression and processing which is defective in AD
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