1,613 research outputs found
Interface of the transport systems research vehicle monochrome display system to the digital autonomous terminal access communication data bus
An upgrade of the transport systems research vehicle (TSRV) experimental flight system retained the original monochrome display system. The original host computer was replaced with a Norden 11/70, a new digital autonomous terminal access communication (DATAC) data bus was installed for data transfer between display system and host, while a new data interface method was required. The new display data interface uses four split phase bipolar (SPBP) serial busses. The DATAC bus uses a shared interface ram (SIR) for intermediate storage of its data transfer. A display interface unit (DIU) was designed and configured to read from and write to the SIR to properly convert the data from parallel to SPBP serial and vice versa. It is found that separation of data for use by each SPBP bus and synchronization of data tranfer throughout the entire experimental flight system are major problems which require solution in DIU design. The techniques used to accomplish these new data interface requirements are described
Multiple agency perspective, family control, and private information abuse in an emerging economy
Using a comprehensive sample of listed companies in Hong Kong this paper investigates how family control affects private information abuses and firm performance in emerging economies. We combine research on stock market microstructure with more recent studies of multiple agency perspectives and argue that family ownership and control over the board increases the risk of private information abuse. This, in turn, has a negative impact on stock market performance. Family control is associated with an incentive to distort information disclosure to minority shareholders and obtain private benefits of control. However, the multiple agency roles of controlling families may have different governance properties in terms of investorsâ perceptions of private information abuse. These findings contribute to our understanding of the conflicting evidence on the governance role of family control within a multiple agency perspectiv
Young women's responses to smoking and breast cancer risk information
Current evidence confirms that young women who smoke or who have regular long-term exposure to secondhand smoke (SHS) have an increased risk of developing premenopausal breast cancer. The aim of this research was to examine the responses of young women to health information about the links between active smoking and SHS exposure and breast cancer and obtain their advice about messaging approaches. Data were collected in focus groups with 46 women, divided in three age cohorts: 15â17, 18â19 and 20â24 and organized according to smoking status (smoking, non-smoking and mixed smoking status groups). The discussion questions were preceded by information about passive and active smoking and its associated breast cancer risk. The study findings show young women's interest in this risk factor for breast cancer. Three themes were drawn from the analysis: making sense of the information on smoking and breast cancer, personal susceptibility and tobacco exposure and suggestions for increasing awareness about tobacco exposure and breast cancer. There was general consensus on framing public awareness messages about this risk factor on âprotecting othersâ from breast cancer to catch smokersâ attention, providing young women with the facts and personal stories of breast cancer to help establish a personal connection with this information and overcome desensitization related to tobacco messages, and targeting all smokers who may place young women at risk. Cautions were also raised about the potential for stigmatization. Implications for raising awareness about this modifiable risk factor for breast cancer are discussed
Size-Dependent Surface Plasmon Dynamics in Metal Nanoparticles
We study the effect of Coulomb correlations on the ultrafast optical dynamics
of small metal particles. We demonstrate that a surface-induced dynamical
screening of the electron-electron interactions leads to quasiparticle
scattering with collective surface excitations. In noble-metal nanoparticles,
it results in an interband resonant scattering of d-holes with surface
plasmons. We show that this size-dependent many-body effect manifests itself in
the differential absorption dynamics for frequencies close to the surface
plasmon resonance. In particular, our self-consistent calculations reveal a
strong frequency dependence of the relaxation, in agreement with recent
femtosecond pump-probe experiments.Comment: 8 pages + 4 figures, final version accepted to PR
Common Scaling Patterns in Intertrade Times of U. S. Stocks
We analyze the sequence of time intervals between consecutive stock trades of
thirty companies representing eight sectors of the U. S. economy over a period
of four years. For all companies we find that: (i) the probability density
function of intertrade times may be fit by a Weibull distribution; (ii) when
appropriately rescaled the probability densities of all companies collapse onto
a single curve implying a universal functional form; (iii) the intertrade times
exhibit power-law correlated behavior within a trading day and a consistently
greater degree of correlation over larger time scales, in agreement with the
correlation behavior of the absolute price returns for the corresponding
company, and (iv) the magnitude series of intertrade time increments is
characterized by long-range power-law correlations suggesting the presence of
nonlinear features in the trading dynamics, while the sign series is
anti-correlated at small scales. Our results suggest that independent of
industry sector, market capitalization and average level of trading activity,
the series of intertrade times exhibit possibly universal scaling patterns,
which may relate to a common mechanism underlying the trading dynamics of
diverse companies. Further, our observation of long-range power-law
correlations and a parallel with the crossover in the scaling of absolute price
returns for each individual stock, support the hypothesis that the dynamics of
transaction times may play a role in the process of price formation.Comment: 8 pages, 5 figures. Presented at The Second Nikkei Econophysics
Workshop, Tokyo, 11-14 Nov. 2002. A subset appears in "The Application of
Econophysics: Proceedings of the Second Nikkei Econophysics Symposium",
editor H. Takayasu (Springer-Verlag, Tokyo, 2003) pp.51-57. Submitted to
Phys. Rev. E on 25 June 200
Analyzing Ideological Communities in Congressional Voting Networks
We here study the behavior of political party members aiming at identifying
how ideological communities are created and evolve over time in diverse
(fragmented and non-fragmented) party systems. Using public voting data of both
Brazil and the US, we propose a methodology to identify and characterize
ideological communities, their member polarization, and how such communities
evolve over time, covering a 15-year period. Our results reveal very distinct
patterns across the two case studies, in terms of both structural and dynamic
properties
Womenâs experiences of wearing therapeutic footwear in three European countries
Background: Therapeutic footwear is recommended for those people with severe foot problems associated with
rheumatoid arthritis (RA). However, it is known that many do not wear them. Although previous European studies
have recommended service and footwear design improvements, it is not known if services have improved or if this
footwear meets the personal needs of people with RA. As an earlier study found that this footwear has more
impact on women than males, this study explores womenâs experiences of the process of being provided with it
and wearing it. No previous work has compared womenâs experiences of this footwear in different countries,
therefore this study aimed to explore the potential differences between the UK, the Netherlands and Spain.
Method: Women with RA and experience of wearing therapeutic footwear were purposively recruited. Ten women
with RA were interviewed in each of the three countries. An interpretive phenomenological approach (IPA) was
adopted during data collection and analysis. Conversational style interviews were used to collect the data.
Results: Six themes were identified: feet being visibly different because of RA; the referring practitionersâ approach
to the patient; the dispensing practitionersâ approach to the patient; the footwear being visible as different to
others; footwear influencing social participation; and the womenâs wishes for improved footwear services. Despite
their nationality, these women revealed that therapeutic footwear invokes emotions of sadness, shame and anger
and that it is often the final and symbolic marker of the effects of RA on self perception and their changed lives.
This results in severe restriction of important activities, particularly those involving social participation. However,
where a patient focussed approach was used, particularly by the practitioners in Spain and the Netherlands, the
acceptance of this footwear was much more evident and there was less wastage as a result of the footwear being
prescribed and then not worn. In the UK, the women were more likely to passively accept the footwear with the
only choice being to reject it once it had been provided. All the women were vocal about what would improve
their experiences and this centred on the consultation with both the referring practitioner and the practitioner that
provides the footwear.
Conclusion: This unique study, carried out in three countries has revealed emotive and personal accounts of what
it is like to have an item of clothing replaced with an âinterventionâ. The participantâs experience of their
consultations with practitioners has revealed the tension between the practitionersâ requirements and the womenâs
âsocialâ needs. Practitioners need greater understanding of the social and emotional consequences of using
therapeutic footwear as an intervention
Size-dependent Correlation Effects in Ultrafast Optical Dynamics of Metal Nanoparticles
We study the role of collective surface excitations in the electron
relaxation in small metal particles. We show that the dynamically screened
electron-electron interaction in a nanoparticle contains a size-dependent
correction induced by the surface. This leads to new channels of quasiparticle
scattering accompanied by the emission of surface collective excitations. We
calculate the energy and temperature dependence of the corresponding rates,
which depend strongly on the nanoparticle size. We show that the
surface-plasmon-mediated scattering rate of a conduction electron increases
with energy, in contrast to that mediated by a bulk plasmon. In noble-metal
particles, we find that the dipole collective excitations (surface plasmons)
mediate a resonant scattering of d-holes to the conduction band. We study the
role of the latter effect in the ultrafast optical dynamics of small
nanoparticles and show that, with decreasing nanoparticle size, it leads to a
drastic change in the differential absorption lineshape and a strong frequency
dependence of the relaxation near the surface plasmon resonance. The
experimental implications of our results in ultrafast pump-probe spectroscopy
are also discussed.Comment: 29 pages including 6 figure
Changes in microphytobenthos fluorescence over a tidal cycle: implications for sampling designs
Intertidal microphytobenthos (MPB) are important primary producers and provide food for herbivores in soft sediments and on rocky shores. Methods of measuring MPB biomass that do not depend on the time of collection relative to the time of day or tidal conditions are important in any studies that need to compare temporal or spatial variation, effects of abiotic factors or activity of grazers. Pulse amplitude modulated (PAM) fluorometry is often used to estimate biomass of MPB because it is a rapid, non-destructive method, but it is not known how measures of fluorescence are altered by changing conditions during a period of low tide. We investigated this experimentally using in situ changes in minimal fluorescence (F) on a rocky shore and on an estuarine mudflat around Sydney (Australia), during low tides. On rocky shores, the time when samples are taken during low tide had little direct influence on measures of fluorescence as long as the substratum is dry. Wetness from wave-splash, seepage from rock pools, run-off, rainfall, etc., had large consequences for any comparisons. On soft sediments, fluorescence was decreased if the sediment dried out, as happens during low-spring tides on particularly hot and dry days. Surface water affected the response of PAM and therefore measurements used to estimate MPB, emphasising the need for care to ensure that representative sampling is done during low tide
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