2,816 research outputs found
A Cognitive Process Model of Trust Change
This paper describes a new process theory model of how trust in a technology changes over time. It proposes that trust change occurs after people pay attention to an event, make sense of it, and pass a threshold for changing their trust level. We call these the cognitive gears of trust. We extend the model with two variance theory factorsâperceived technology risk and loyalty to the technology vendorâ which should also affect how trust changes over time. Using hierarchical linear modeling we analyze data from 1799 respondents who report their trust after seeing eight successive news briefs about the technology. We find the effects on trust change of three cognitive processesâattention, sensemaking, and threshold as well as two factorsâtech risk and loyalty
Emissions of ultrafine particles from civil aircraft:dependence upon aircraft type and passenger load
Very high concentrations of ultrafine particles (UFP) were measured at Heathrow Airport London. Exposure to UFP is strongly linked to adverse health effects and guidance for exposure limits has recently been provided by the World Health Organization (WHO). Using 1 s resolution UFP measurements and aircraft GPS data, measurements were assigned to individual aircraft and their operating mode, and this information was used to model UFP emission rates. In all cases, the highest emission rates were associated with departing aircraft, with rates for larger aircraft higher than smaller aircraft. Emission rates per passenger is influenced by the number of passengers carried, especially for arriving aircraft. Calculated emission rates are significantly higher than stated literature values, due to the inclusion of condensable particles in the measurements. These condensable particles are specifically not included in the regulated emission rates. Measured UFP concentrations within the airport boundary (and therefore not accessible to the general public) exceed the WHO guidance, indicating that UFP concentrations outside of the airport boundary could also be of concern. Assessing population exposure close to airports will be of increasing importance in future
ProtoEXIST: Advanced Prototype CZT Coded Aperture Telescopes for EXIST
{\it ProtoEXIST1} is a pathfinder for the {\it EXIST-HET}, a coded aperture
hard X-ray telescope with a 4.5 m CZT detector plane a 9070 degree
field of view to be flown as the primary instrument on the {\it EXIST} mission
and is intended to monitor the full sky every 3 h in an effort to locate GRBs
and other high energy transients. {\it ProtoEXIST1} consists of a 256 cm
tiled CZT detector plane containing 4096 pixels composed of an 88 array
of individual 1.95 cm 1.95 cm 0.5 cm CZT detector modules
each with a 8 8 pixilated anode configured as a coded aperture
telescope with a fully coded field of view employing
passive side shielding and an active CsI anti-coincidence rear shield, recently
completed its maiden flight out of Ft. Sumner, NM on the 9th of October 2009.
During the duration of its 6 hour flight on-board calibration of the detector
plane was carried out utilizing a single tagged 198.8 nCi Am-241 source along
with the simultaneous measurement of the background spectrum and an observation
of Cygnus X-1. Here we recount the events of the flight and report on the
detector performance in a near space environment. We also briefly discuss {\it
ProtoEXIST2}: the next stage of detector development which employs the {\it
NuSTAR} ASIC enabling finer (3232) anode pixilation. When completed
{\it ProtoEXIST2} will consist of a 256 cm tiled array and be flown
simultaneously with the ProtoEXIST1 telescope
The Rising Incidence of Type 1 Diabetes Is Accounted for by Cases With Lower-Risk Human Leukocyte Antigen Genotypes
OBJECTIVEâThe rising incidence of type 1 diabetes has been attributed to environment, implying a lesser role for genetic susceptibility. However, the rise could be accounted for by either more cases with classic high-risk genes or by cases with other risk genes. Separately, for any degree of genetic susceptibility, age at presentation may decrease in a permissive environment. To examine these possibilities, human leukocyte antigen (HLA) class II DRB1 genes known to confer risk for type 1 diabetes were analyzed in relation to year of birth and age at diagnosis over the last five decades
What Brown saw and you can too
A discussion is given of Robert Brown's original observations of particles
ejected by pollen of the plant \textit{Clarkia pulchella} undergoing what is
now called Brownian motion. We consider the nature of those particles, and how
he misinterpreted the Airy disc of the smallest particles to be universal
organic building blocks. Relevant qualitative and quantitative investigations
with a modern microscope and with a "homemade" single lens microscope similar
to Brown's, are presented.Comment: 14.1 pages, 11 figures, to be published in the American Journal of
Physics. This differs from the previous version only in the web site referred
to in reference 3. Today, this Brownian motion web site was launched, and
http://physerver.hamilton.edu/Research/Brownian/index.html, is now correc
Mortality following Traumatic Brain Injury among Individuals Unable to Follow Commands at the Time of Rehabilitation Admission: A National Institute on Disability and Rehabilitation Research Traumatic Brain Injury Model Systems Study
Severe traumatic brain injury (TBI) has been associated with increased mortality. This study characterizes long-term mortality, life expectancy, causes of death, and risk factors for death among patients admitted within the National Institute on Disability and Rehabilitation Research (NIDRR) TBI Model Systems Programs (TBIMS) who lack command following at the time of admission for inpatient TBI rehabilitation. Of the 8084 persons enrolled from 1988 and 2009, 387 from 20 centers met study criteria. Individuals with moderate to severe TBI who received inpatient rehabilitation were 2.2 times more likely to die than individuals in the U.S. general population of similar age, gender, and race, with an average life expectancy (LE) reduction of 6.6 years. The subset of individuals who were unable to follow commands on admission to rehabilitation was 6.9 times more likely to die, with an average LE reduction of 12.2 years. Relative to the U.S. general population matched for age, gender, and race/ethnicity, these nonâcommand following individuals were more than four times more likely to die of circulatory conditions, 44 times more likely to die of pneumonia, and 38 times more likely to die of aspiration pneumonia. The subset of individuals with TBI who are unable to follow commands upon admission to inpatient rehabilitation are at a significantly increased risk of death when compared with the U.S. general population and compared with all individuals with moderate to severe TBI receiving inpatient rehabilitation. Respiratory causes of death predominate, compared with the general population
Episodic X-ray Emission Accompanying the Activation of an Eruptive Prominence: Evidence of Episodic Magnetic Reconnection
We present an X-ray imaging and spectroscopic study of a partially occulted
C7.7 flare on 2003 April 24 observed by RHESSI that accompanied a prominence
eruption observed by TRACE. (1) The activation and rise of the prominence
occurs during the preheating phase of the flare. The initial X-ray emission
appears as a single coronal source at one leg of the prominence and it then
splits into a double source. Such a source splitting happens three times, each
coinciding with an increased X-ray flux and plasma temperature, suggestive of
fast reconnection in a localized current sheet and an enhanced energy release
rate. In the late stage of this phase, the prominence displays a helical
structure. These observations are consistent with the tether-cutting and/or
kink instability model for triggering solar eruptions. (2) The eruption of the
prominence takes place during the flare impulsive phase. Since then, there
appear signatures predicted by the classical CSHKP model of two-ribbon flares
occurring in a vertical current sheet trailing an eruption. These signatures
include an EUV cusp and current-sheet-like feature (or ridge) above it. There
is also X-ray emission along the EUV ridge both below and above the cusp, which
in both regions appears closer to the cusp at higher energies in the thermal
regime. This trend is reversed in the nonthermal regime. (3) Spectral analysis
indicates thermal X-rays from all sources throughout the flare, while during
the impulsive phase there is additional nonthermal emission which primarily
comes from the coronal source below the cusp. This source also has a lower
temperature, a higher emission measure, and a much harder nonthermal spectrum
than the upper sources.Comment: 8 pages, 5 figures, submitted to Ap
High-resolution temporal profiling of transcripts during Arabidopsis leaf senescence reveals a distinct chronology of processes and regulation
Leaf senescence is an essential developmental process that impacts dramatically on crop yields and involves altered
regulation of thousands of genes and many metabolic and signaling pathways, resulting in major changes in the leaf. The
regulation of senescence is complex, and although senescence regulatory genes have been characterized, there is little
information on how these function in the global control of the process. We used microarray analysis to obtain a highresolution
time-course profile of gene expression during development of a single leaf over a 3-week period to senescence.
A complex experimental design approach and a combination of methods were used to extract high-quality replicated data
and to identify differentially expressed genes. The multiple time points enable the use of highly informative clustering to
reveal distinct time points at which signaling and metabolic pathways change. Analysis of motif enrichment, as well
as comparison of transcription factor (TF) families showing altered expression over the time course, identify clear groups
of TFs active at different stages of leaf development and senescence. These data enable connection of metabolic
processes, signaling pathways, and specific TF activity, which will underpin the development of network models to
elucidate the process of senescence
A comprehensive study of GRB 070125, a most energetic gamma ray burst
We present a comprehensive multiwavelength analysis of the bright, long
duration gamma-ray burst GRB 070125, comprised of observations in -ray,
X-ray, optical, millimeter and centimeter wavebands. Simultaneous fits to the
optical and X-ray light curves favor a break on day 3.78, which we interpret as
the jet break from a collimated outflow. Independent fits to optical and X-ray
bands give similar results in the optical bands but shift the jet break to
around day 10 in the X-ray light curve. We show that for the physical
parameters derived for GRB 070125, inverse Compton scattering effects are
important throughout the afterglow evolution. While inverse Compton scattering
does not affect radio and optical bands, it may be a promising candidate to
delay the jet break in the X-ray band. Radio light curves show rapid flux
variations, which are interpreted as due to interstellar scintillation, and are
used to derive an upper limit of cm on the radius of the
fireball in the lateral expansion phase of the jet. Radio light curves and
spectra suggest a high synchrotron self absorption frequency indicative of the
afterglow shock wave moving in a dense medium. Our broadband modeling favors a
constant density profile for the circumburst medium over a wind-like profile
(). However, keeping in mind the uncertainty of the parameters, it is
difficult to unambiguously distinguish between the two density profiles. Our
broadband fits suggest that \event is a burst with high radiative efficiency
().Comment: 50 pages, 33 figures, sty file included, Appeared in 20 Aug 2008
edition of Astrophysical Journa
Variation in suspected cancer referral pathways in primary care:comparative analysis across the International Benchmarking Cancer Partnership
BACKGROUND: International variations in cancer outcomes persist and may be influenced by differences in the accessibility and organisation of cancer patient pathways. More evidence is needed to understand to what extent variations in the structure of primary care referral pathways for cancer investigation contribute to differences in the timeliness of diagnoses and cancer outcomes in different countries. AIM: To explore the variation in primary care referral pathways for the management of suspected cancer across different countries. DESIGN AND SETTING: Descriptive comparative analysis using mixed methods across the International Cancer Benchmarking Partnership (ICBP) countries. METHOD: Schematics of primary care referral pathways were developed across 10 ICBP jurisdictions. The schematics were initially developed using the Aarhus statement (a resource providing greater insight and precision into early cancer diagnosis research) and were further supplemented with expert insights through consulting leading experts in primary care and cancer, existing ICBP data, a focused review of existing evidence on the management of suspected cancer, published primary care cancer guidelines, and evaluations of referral tools and initiatives in primary care. RESULTS: Referral pathway schematics for 10 ICBP jurisdictions were presented alongside a descriptive comparison of the organisation of primary care management of suspected cancer. Several key areas of variation across countries were identified: inflexibility of referral pathways, lack of a managed route for non-specific symptoms, primary care practitioner decision-making autonomy, direct access to investigations, and use of emergency routes. CONCLUSION: Analysing the differences in referral processes can prompt further research to better understand the impact of variation on the timeliness of diagnoses and cancer outcomes. Studying these schematics in local contexts may help to identify opportunities to improve care and facilitate discussions on what may constitute best referral practice
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