26,641 research outputs found
Pure quantum freezing of the 5 dimension
It is shown that superthin and superlong gravitational flux tube solutions in
the 5D Kaluza-Klein gravity have the region where the metric
signature changes from to . Such change is too
quickly from one of the paradigms of quantum gravity which tells that the
Planck length is the minimal length in the nature and consequently the physical
quantities can not change very quickly in the course of this length. For
avoiding such dynamic it is supposed that a pure quantum freezing of the
dynamic of the dimension takes place. As the continuation of the flux
tube metric in the longitudinal direction the Reissner-Nordstr\"om metric is
proposed. In the consequence of such construction one can avoid the appearance
of a point-like singularity in the extremal Reissner-Nordstr\"om solution.Comment: grammar errors are correcte
Detection of radio frequency magnetic fields using nonlinear magneto-optical rotation
We describe a room-temperature alkali-metal atomic magnetometer for detection
of small, high frequency magnetic fields. The magnetometer operates by
detecting optical rotation due to the precession of an aligned ground state in
the presence of a small oscillating magnetic field. The resonance frequency of
the magnetometer can be adjusted to any desired value by tuning the bias
magnetic field. We demonstrate a sensitivity of in a 3.5 cm diameter, paraffin coated cell. Based
on detection at the photon shot-noise limit, we project a sensitivity of
.Comment: 6 pages, 6 figure
Promoting Team-Based Exercise Among African American Breast Cancer Survivors
Physical activity benefits the health and well-being of breast cancer survivors (BCS). Yet, many African American survivors do not routinely exercise and have increased risk of poor outcomes. The purpose of this mixed-method study was to identify motivational factors compelling African American BCS to participate in a 14-week team walking program and to intend to continue exercise after the intervention concluded. Focus groups were held with participants (n = 12) before and after training. Content analysis discovered themes before the intervention: Not wanting to go at it alone, exercise not a life or treatment priority, cancer treatment affected activity, advocates to exercise, and can exercise really help? Four themes postintervention themes included: In the same boat, changed mind-set, improved weight and activity, and overcoming barriers. Physical data verified improvements. Results suggest that a team-based exercise training program may assist in overcoming a sedentary behavior tendency and subsequently improve health among survivors
Survivors Speak: A Qualitative Analysis of Motivational Factors Influencing Breast Cancer Survivors’ Participation in a Sprint Distance Triathlon
Aims and Objectives
To examine motivational factors influencing breast cancer survivors to participate in triathlon training, complete a triathlon and maintain an exercise thereafter.
Background
Routine exercise has been shown to improve quality of life and reduce recurrence for breast cancer survivors. Yet physical and psychological factors present barriers for initiating and maintaining an exercise routine. Research is limited in exploring factors of exercise motivation from the survivor\u27s perspective.
Design
Qualitative design using focus groups and individual follow-up phone interviews to explore motivation for exercise initiation and maintenance.
Methods
One to two weeks after completing a triathlon, 11 breast cancer survivors who trained together participated in one of three focus groups to discuss their experience. Five months post triathlon 6 of the 11 participants were successfully contacted and phone interviews were conducted to explore exercise maintenance. Focus groups and interviews were analysed using content and thematic analysis.
Results
Five themes emerged (1) Champion for Exercise, (2) Part of a Team, (3) Everyone Had a Story, (4) Not Really Exercise and (5) What Do We Do Now? Overall, survivors recognised their need for lifestyle change (e.g. moving from a sedentary lifestyle to a more active one). More importantly, they identified the team approach to exercise initiation was crucial in their success in sustaining a behavioural change.
Conclusions
Emphasis needed on developing team exercise training programmes for survivors. Nurses can play a critical role in discussing with survivors, the benefits of exercise initiation and maintenance.
Relevance to clinical practice
Breast cancer survivors are hesitant to initiate routine exercise. Training with women who share a common lived experience increases the likelihood of success. Nurses are in a position to encourage breast cancer survivors to participate in group exercise programmes as a way to improve quality of life
Investigation of microwave transitions and nonlinear magneto-optical rotation in anti-relaxation-coated cells
Using laser optical pumping, widths and frequency shifts are determined for
microwave transitions between ground-state hyperfine components of Rb
and Rb atoms contained in vapor cells with alkane anti-relaxation
coatings. The results are compared with data on Zeeman relaxation obtained in
nonlinear magneto-optical rotation (NMOR) experiments, a comparison important
for quantitative understanding of spin-relaxation mechanisms in coated cells.
By comparing cells manufactured over a forty-year period we demonstrate the
long-term stability of coated cells, an important property for atomic clocks
and magnetometers
Linear polarization of light by two wheat canopies measured at many view angles
The linear polarization and reflection of visible light by wheat as a function of sun-view directions, crop development stage, and wavelength were examined. Two-hundred spectra were taken continuously in wave-lengths from 0.45 to 0.72 Micron in 33 view directions using an Exotech model 20C spectroradiometer six meters above two wheat canopies in the boot and fully headed maturity stages. The analysis results show that the amount of linearly polarized light from the wheat canopies is greatest in the blue spectral region and decreases gradually with increasing wavelength. The results also show that the linearly polarized light from the canopies is generally greatest in the azimuth direction of the Sun and tends toward zero as the view direction tends toward the direction of the hot spot or anti-solar point. It is demonstrated that the single, angle of incidence of sunlight on the leaf, explains almost all of the variation of the amount of polarized light with Sun-view direction
Simulated response of a multispectral scanner over wheat as a function of wavelength and view/illumination direction
The reflectance response with view angle of wheat, was analyzed. The analyses, which assumes there are no atmospheric effects, and otherwise simulates the response of a multispectral scanner, is based upon spectra taken continuously in wavelength from 0.45 to 2.4 micrometers at more than 1200 view/illumination directions using an Exotech model 20C spectra radiometer. Data were acquired six meters above four wheat canopies, each at a different growth stage. The analysis shows that the canopy reflective response is a pronounced function of illumination angle, scanner view angle and wavelength. The variation is greater at low solar elevations compared to high solar elevations
Type Ia supernova counts at high z: signatures of cosmological models and progenitors
Determination of the rates at which supernovae of Type Ia (SNe Ia) occur in
the early Universe can give signatures of the time spent by the binary
progenitor systems to reach explosion and of the geometry of the Universe.
Observations made within the Supernova Cosmology Project are already providing
the first numbers. Here it is shown that, for any assumed SNe Ia progenitor,
SNe Ia counts up to are useful tests of the SNe Ia
progenitor systems and cosmological tracers of a possible non-zero value of the
cosmological constant, . The SNe Ia counts at high redshifts compare
differently with those at lower redshifts depending on the cosmological model.
Flat --dominated universes would show a more significant
increase of the SNe Ia counts at than a flat,
universe. Here we consider three sorts of universes: a flat universe with
, , ;
an open universe with , ,
; and a flat, --dominated universe with , , ). On the
other hand, the SNe Ia counts from one class of binary progenitors (double
degenerate systems) should not increase steeply in the to range,
contrary to what should be seen for other binary progenitors. A measurement of
the SNe Ia counts up to is within reach of ongoing SNe Ia searches
at high redshifts.Comment: 16 pages, incl. 2 figures. To appear in ApJ (Letters
A multiband radiometer and data acquisition system for remote sensing field research
Specifications are described for a recently developed prototype multispectral data acquisition system which consists of multiband radiometer with 8 bands between 0.4 and 12.5 micrometers and a data recording module to record data from the radometer and ancillary sources. The systems is adaptable to helicopter, truck, or tripod platforms, as well as hand-held operation. The general characteristics are: (1) comparatively inexpensive to acquire, maintain and operate; (2) simple to operate and calibrate; (3) complete with data hardware and software; and (4) well documented for use by researchers. The instrument system is to be commercially available and can be utilized by many researchers to obtain large numbers of accurate, calibrated spectral measurements. It can be a key element in improving and advancing the capability for field research in remote sensing
Cluster spacecraft observations of a ULF wave enhanced by Space Plasma Exploration by Active Radar (SPEAR)
Space Plasma Exploration by Active Radar (SPEAR) is a high-latitude ionospheric heating facility capable of exciting ULF waves on local magnetic field lines. We examine an interval from 1 February 2006 when SPEAR was transmitting a 1 Hz modulation signal with a 10 min on-off cycle. Ground magnetometer data indicated that SPEAR modulated currents in the local ionosphere at 1 Hz, and enhanced a natural field line resonance with a 10 min period. During this interval the Cluster spacecraft passed over the heater site. Signatures of the SPEAR-enhanced field line resonance were present in the magnetic field data measured by the magnetometer on-board Cluster-2. These are the first joint ground- and space-based detections of field line tagging by SPEAR
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