4,792 research outputs found
The physics of the sheath effects in monopole plasma antenna or helix plasma antenna
The magnetic field in the sheath of monopole plasma antenna or the helix antennas has been found to have a negative impact on its general functionality. The vertical and horizontal signals at predetermined angles had been compromised by the sheath effect. It was observed that this phenomenon is almost unnoticed because magnetization has the highest magnitude when the device is switch on/off. In microscopic scale (monopole plasma antenna), the sheath effect is due to femto spin demagnetization of particulates. However, in macroscopic scale (helix antenna), the sheath effect is due to signal impairment
ICE/ISEE plasma wave data analysis
This report is one of the final processing of ICE plasma wave (pw) data and analysis of late ISEE 3, ICE cometary, and ICE cruise trajectory data, where coronal mass ejections (CME's) were the first locus of attention. Interest in CME's inspired an effort to represent our pw data in a condensed spectrogram format that facilitated rapid digestion of interplanetary phenomena on long (greater than 1 day) time scales. The format serendipitously allowed us to also examine earth-orbiting data from a new perspective, invigorating older areas of investigation in Earth's immediate environment. We, therefore, continued to examine with great interest the last year of ISEE 3's precomet phase, when it spent considerable time far downwind from Earth, recording for days on end conditions upstream, downstream, and across the very weak, distant flank bow shock. Among other motivations has been the apparent similarity of some shock and post shock structures to the signatures of the bow wave surrounding comet Giacobini-Zinner, whose ICE-phase data we revisited
Study of an attitude control system for the astronaut maneuvering unit final report, dec. 1963 - jul. 1964
Attitude control system for astronaut maneuvering unit
Systemic Study of Aerosol Loading and Retention over Praia-Cape Verde: Satellite and Ground Observation Analysis
The situation in Praia may be critical at the moment because of its current aerosol loading
and retention. In this study we obtained 14-year (2000-13) data set from satellite and ground observation
from a multi-angle imaging spectro-radiometer (MISR) and an aerosol robotic network (AERONET).
The analytic and statistical techniques were used to investigate the aerosol loading and retention over
Praia-Cape Verde. The average annual aerosol retention over the study area increased by 18%. The highest
aerosol retention rate of 39% was recorded in 2010. The aerosol loading was found to be higher between
December to February. Since the ventilation over Praia is low, aerosol loading impact on the health
and welfare of life forms may be threatened. The study also suggested other sectors of the economy that
can be affected by the increased aerosol loading over Praia
Motive8!: feasibility of a text messaging intervention to promote physical activity in knee osteoarthritis
Aim: To develop and test the feasibility of using a SMS text messaging intervention to promote physical activity in patients with knee OA.
Methods: 27 people (6 male, 21 female; aged 25-81 years) with knee osteoarthritis received 4 text messages per week, for 6 weeks. Telephone surveys were conducted at baseline and 6 weeks to measure physical activity levels and beliefs, including self-efficacy for exercise, barriers and benefits of exercise, social support and pain. Participants completed physical activity diaries. Process evaluation included participant perceptions of the intervention and 'real-time' data on intervention fidelity (automated collection of delivery and response data) and participant engagement (text response).
Results: 648 messages were sent, 100% were accurately delivered. From baseline to 6 weeks, physical activity, self-efficacy for exercise, perceived benefits of exercise and social support significantly increased; reductions were observed in barriers to exercise and pain. Participants engaged with the intervention; 100% read the messages, 89% responded to texts requesting replies, 64% completed physical activity diaries with low attenuation (1.8% drop) by six weeks. Participants perceived messaging to be enjoyable (96%), personally relevant (85%), of appropriate frequency (100%) and duration (88%). Mobile phones, email and web were perceived to be most acceptable for health promotion compared with other forms of technology.
Conclusions: People with knee osteoarthritis can engage meaningfully with an interactive mobile phone messaging intervention over a six-week period. Health communications promoting physical activity demonstrate potential for behaviour change and positive implications for perceptions of exercise and pain; this needs to be tested in a randomised trial. Data collected in 'real-time' can be used for process evaluation to demonstrate participant engagement and intervention fidelity
Plume motion and large-scale circulation in a cylindrical Rayleigh-B\'enard cell
We used the time correlation of shadowgraph images to determine the angle
of the horizontal component of the plume velocity above (below) the
center of the bottom (top) plate of a cylindrical Rayleigh-B\'enard cell of
aspect ratio ( is the diameter and mm
the height) in the Rayleigh-number range for a Prandtl number . We expect that gives the
direction of the large-scale circulation. It oscillates time-periodically. Near
the top and bottom plates has the same frequency but is
anti-correlated.Comment: 4 pages, 6 figure
Molecular Model of the Contractile Ring
We present a model for the actin contractile ring of adherent animal cells.
The model suggests that the actin concentration within the ring and
consequently the power that the ring exerts both increase during contraction.
We demonstrate the crucial role of actin polymerization and depolymerization
throughout cytokinesis, and the dominance of viscous dissipation in the
dynamics. The physical origin of two phases in cytokinesis dynamics ("biphasic
cytokinesis") follows from a limitation on the actin density. The model is
consistent with a wide range of measurements of the midzone of dividing animal
cells.Comment: PACS numbers: 87.16.Ka, 87.16.Ac
http://www.ncbi.nlm.nih.gov/pubmed/16197254
http://www.weizmann.ac.il/complex/tlusty/papers/PhysRevLett2005.pd
Spontaneous emission and lifetime modification caused by an intense electromagnetic field
We study the temporal evolution of a three-level system (such as an atom or a
molecule), initially prepared in an excited state, bathed in a laser field
tuned at the transition frequency of the other level. The features of the
spontaneous emission are investigated and the lifetime of the initial state is
evaluated: a Fermi "golden rule" still applies, but the on-shell matrix
elements depend on the intensity of the laser field. In general, the lifetime
is a decreasing function of the laser intensity. The phenomenon we discuss can
be viewed as an "inverse" quantum Zeno effect and can be analyzed in terms of
dressed states.Comment: 25 pages, 6 figure
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Challenges and Opportunities to Updating Prescribing Information for Longstanding Oncology Drugs.
A number of important drugs used to treat cancer-many of which serve as the backbone of modern chemotherapy regimens-have outdated prescribing information in their drug labeling. The Food and Drug Administration is undertaking a pilot project to develop a process and criteria for updating prescribing information for longstanding oncology drugs, based on the breadth of knowledge the cancer community has accumulated with the use of these drugs over time. This article highlights a number of considerations for labeling updates, including selecting priorities for updating; data sources and evidentiary criteria; as well as the risks, challenges, and opportunities for iterative review to ensure prescribing information for oncology drugs remains relevant to current clinical practice
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