8,590 research outputs found
Identifying the attitudes and beliefs about performance enhancing drugs: from the Coach Potato to the Athlete
Social science research has much to offer the field of anti-doping in sport. In particular, health psychology models that address behaviour change may be the key to
identifying the decision making process around compliance with anti-doping policy. Constructs of the Health Action Process Approach (HAPA), such as decisional balance,
ambivalence, self-efficacy, situational temptations, and perceived reward for effort, may impact an athletes desire to engage in performance enhancing behaviours or for support
personnel to facilitate this behaviour. Thus, health psychology methods and clinical techniques have been incorporated into a mixed methods research design to identify those factors that may be linked to compliance or non compliance with anti-doping policy in sport. This approach has been highlighted in the research priorities of both the World Anti Doping Agency (WADA) and the Australian Sport and Anti-Doping Authority (ASADA).
Five experimental groups were incorporated in the design of this study: nonactive participants, regular exercisers, amateur sporting club members, professional athletes, and coaches or trainers. The sample size for each experimental group is 50 (n=250). Each participant was presented with a randomised selection of scenarios describing a sports person in a number of different settings (e.g. in competition, with an injury). Participants were asked to provide their view in relation to what the advantages and disadvantages might be for the athlete in the scenario in using and not using performance enhancing drugs or methods. A sub-sample of participants also contributed to qualitative interviews that extended upon these factors.
Quantitative and qualitative analysis focused on the different influencing factors of performance enhancement identified across the different levels of engagement in sport. The issues and factors highlighted will contribute to a pool of items for consideration in a measure developed to assess attitudes to performance enhancement in sport
Morphological analysis of the cm-wave continuum in the dark cloud LDN1622
The spectral energy distribution of the dark cloud LDN1622, as measured by
Finkbeiner using WMAP data, drops above 30GHz and is suggestive of a Boltzmann
cutoff in grain rotation frequencies, characteristic of spinning dust emission.
LDN1622 is conspicuous in the 31 GHz image we obtained with the Cosmic
Background Imager, which is the first cm-wave resolved image of a dark cloud.
The 31GHz emission follows the emission traced by the four IRAS bands. The
normalised cross-correlation of the 31 GHz image with the IRAS images is higher
by 6.6sigma for the 12um and 25um bands than for the 60um and 100um bands:
C(12+25) = 0.76+/-0.02 and C(60+100) = 0.64+/-0.01.
The mid-IR -- cm-wave correlation in LDN 1622 is evidence for very small
grain (VSG) or continuum emission at 26-36GHz from a hot molecular phase. In
dark clouds and their photon-dominated regions (PDRs) the 12um and 25um
emission is attributed to stochastic heating of the VSGs. The mid-IR and
cm-wave dust emissions arise in a limb-brightened shell coincident with the PDR
of LDN1622, where the incident UV radiation from the Ori OB1b association heats
and charges the grains, as required for spinning dust.Comment: accepted for publication in ApJ - the complete article with
uncompressed figures may be downloaded from
http://www.das.uchile.cl/~simon/ftp/l1622.pd
A High-speed Engine Pressure Indicator of the Balanced Diaphragm Type
This report describes a pressure-measuring device especially adapted for use in mapping indicator diagrams of high-speed internal combustion engines. The cards are obtained by a point-to-point method giving the average of a large number of engine cycles. The principle involved is the balancing of the engine cylinder pressure against a measured pressure on the opposite side of the metal a diaphragm of negligible stiffness. In its application as an engine indicator the phase of the engine cycle to which a pressure measurement corresponds is selected by a timing device. The report discusses briefly the errors which must be avoided in the development of an indicator for light high-speed engines, where vibration is serious, and outlines the principles underlying the design of this instrument in order to be free of such errors. A detailed description of the instrument and accessories follows together with operating directions
A Radio Determination of the Time of the New Moon
The detection of the New Moon at sunset is of importance to communities based
on the lunar calendar. This is traditionally undertaken with visual
observations. We propose a radio method which allows a higher visibility of the
Moon relative to the Sun and consequently gives us the ability to detect the
Moon much closer to the Sun than is the case of visual observation. We first
compare the relative brightness of the Moon and Sun over a range of possible
frequencies and find the range 5--100\,GHz to be suitable. The next
consideration is the atmospheric absorption/emission due to water vapour and
oxygen as a function of frequency. This is particularly important since the
relevant observations are near the horizon. We show that a frequency of GHz is optimal for this programme. We have designed and constructed a
telescope with a FWHM resolution of 0.6 and low sidelobes to
demonstrate the potential of this approach. At the time of the 21 May 2012 New
Moon the Sun/Moon brightness temperature ratio was in agreement
with predictions from the literature when combined with the observed sunspot
numbers for the day. The Moon would have been readily detectable at from the Sun. Our observations at 16\,hr\,36\,min UT indicated that
the Moon would have been at closest approach to the Sun 16\,hr\,25\,min
earlier; this was the annular solar eclipse of 00\,hr\,00\,min\,UT on 21 May
2012.Comment: 11 pages, 15 figures, accepted for publication in MNRA
The Stellar Populations and Evolution of Lyman Break Galaxies
Using deep near-IR and optical observations of the HDF-N from the HST NICMOS
and WFPC2 and from the ground, we examine the spectral energy distributions
(SEDs) of Lyman break galaxies (LBGs) at 2.0 < z < 3.5. The UV-to-optical
rest-frame SEDs of the galaxies are much bluer than those of present-day spiral
and elliptical galaxies, and are generally similar to those of local starburst
galaxies with modest amounts of reddening. We use stellar population synthesis
models to study the properties of the stars that dominate the light from LBGs.
Under the assumption that the star-formation rate is continuous or decreasing
with time, the best-fitting models provide a lower bound on the LBG mass
estimates. LBGs with ``L*'' UV luminosities are estimated to have minimum
stellar masses ~ 10^10 solar masses, or roughly 1/10th that of a present-day L*
galaxy. By considering the effects of a second component of maximally-old
stars, we set an upper bound on the stellar masses that is ~ 3-8 times the
minimum estimate. We find only loose constraints on the individual galaxy ages,
extinction, metallicities, initial mass functions, and prior star-formation
histories. We find no galaxies whose SEDs are consistent with young (< 10^8
yr), dust-free objects, which suggests that LBGs are not dominated by ``first
generation'' stars, and that such objects are rare at these redshifts. We also
find that the typical ages for the observed star-formation events are
significantly younger than the time interval covered by this redshift range (~
1.5 Gyr). From this, and from the relative absence of candidates for quiescent,
non-star-forming galaxies at these redshifts in the NICMOS data, we suggest
that star formation in LBGs may be recurrent, with short duty cycles and a
timescale between star-formation events of < 1 Gyr. [Abridged]Comment: LaTeX, 37 pages, 21 figures. Accepted for publication in the
Astrophysical Journa
Far-ultraviolet imaging of the Hubble Deep Field-North: Star formation in normal galaxies at z < 1
We present far-ultraviolet (FUV) imaging of the Hubble Deep Field-North (HDF-N) taken with the Solar Blind Channel of the Advanced Camera for Surveys (ACS SBC) and the FUV MAMA detector of the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. The full WFPC2 deep field has been observed at 1600 Ă
. We detect 134 galaxies and one star down to a limit of FUV_(AB) ~ 29. All sources have counterparts in the WFPC2 image. Redshifts (spectroscopic or photometric) for the detected sources are in the range 0 < z < 1. We find that the FUV galaxy number counts are higher than those reported by GALEX, which we attribute at least in part to cosmic variance in the small HDF-N field of view. Six of the 13 Chandra sources at z < 0.85 in the HDF-N are detected in the FUV, and those are consistent with starbursts rather than active galactic nuclei. Cross-correlating with Spitzer sources in the field, we find that the FUV detections show general agreement with the expected L_(IR)/L_(UV) versus ÎČ relationship. We infer star formation rates (SFRs), corrected for extinction using the UV slope, and find a median value of 0.3 M_â yr^(-1) for FUV-detected galaxies, with 75% of detected sources having SFR < 1 M_â yr^(-1). Examining the morphological distribution of sources, we find that about half of all FUV-detected sources are identified as spiral galaxies. Half of morphologically selected spheroid galaxies at z < 0.85 are detected in the FUV, suggesting that such sources have had significant ongoing star formation in the epoch since z ~ 1
Collaborative Travel Apps, Reciprocity and the Internet of Things
As cities become increasingly connected, both people and objects can connect to the Internet to transmit and receive information. This is the Internet of Things. Smartphone
technology can help identify current and anticipate future patterns of behaviour and, with its social networking capabilities, allow users to imagine collaborative opportunities. This has led to the development of collaborative travel apps designed to enable activities like lift sharing. However, two projects working with community based travel collaboration apps identify significant challenges to people accessing forms of travel assistance due to the imperative of reciprocity.
Collaborative travel apps depend on users to offer help, but they also need users to ask for or accept help. This paper analyses the fundamental challenges of reciprocity as facilitated by these apps and considers how the near future Internet of Things might alter practices.Trials of purpose built collaborative travel apps were conducted across four communities (a campsite, two rural villages and an urban fringe estate) during 2013 and 2014 involving 66
participants. Data were collected by in-depth interviews and all app activities (messages and transactions) were recorded through a linked database.Offers of help dominated in contrast to requests for and acceptance of help.Feelings of indebtedness inhibit app use since they threa ten a userâs status, power and freedom of action with respect to the donor of help. Other transport issues of flexibility and control were also apparent. The paper discusses how indebtedness might be addressed during the design and implementation of such apps. Also, the emergence of the Internet of Things, with its more anticipatory systems, prompts a reappraisal of current Internet based collaborative communities which raises questions about the human regulation of reciprocal arrangements and presents opportunities for parties who are less able to reciprocate such as the ageing population
Neuromuscular control of wingbeat kinematics in Anna's hummingbirds (Calypte anna)
Hummingbirds can maintain the highest wingbeat frequencies of any flying vertebrate â a feat accomplished by the large pectoral muscles that power the wing strokes. An unusual feature of these muscles is that they are activated by one or a few spikes per cycle as revealed by electromyogram recordings (EMGs). The relatively simple nature of this activation pattern provides an opportunity to understand how motor units are recruited to modulate limb kinematics. Hummingbirds made to fly in low-density air responded by moderately increasing wingbeat frequency and substantially increasing the wing stroke amplitude as compared with flight in normal air. There was little change in the number of spikes per EMG burst in the pectoralis major muscle between flight in normal and low-density heliox (mean=1.4 spikes cycle^(â1)). However the spike amplitude, which we take to be an indication of the number of active motor units, increased in concert with the wing stroke amplitude, 1.7 times the value in air. We also challenged the hummingbirds using transient load lifting to elicit maximum burst performance. During maximum load lifting, both wing stroke amplitude and wingbeat frequency increased substantially above those values during hovering flight. The number of spikes per EMG burst increased to a mean of 3.3 per cycle, and the maximum spike amplitude increased to approximately 1.6 times those values during flight in heliox. These results suggest that hummingbirds recruit additional motor units (spatial recruitment) to regulate wing stroke amplitude but that temporal recruitment is also required to maintain maximum stroke amplitude at the highest wingbeat frequencies
Deep Observations of Lyman Break Galaxies
We summarise the main results of recent work on the Lyman break galaxy
population which takes advantage of newly commissioned instrumentation on the
VLT and Keck telescopes to push the detection of these objects to new
wavelengths and more sensitive limits. We focus in particular on near-infrared
observations targeted at detecting emission lines of [O II], [O III], and
H-beta and on the first tentative detection of Lyman continuum emission from
star forming galaxies at z = 3.Comment: 9 pages, LaTeX, 6 Postscript Figures. To appear in the Proceedings of
the ESO Symposium: Deep Fields, ed. S. Cristiani (Berlin: Springer
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