1,282 research outputs found
What very small numbers mean.
This article presents a theoretical and experimental framework for assessing the biases associated with the interpretation of numbers. This framework consists of having participants convert between different representations of quantities. These representations should include both variations in numerical labels that symbolize quantities and variations in displays in which quantity is inherent. Five experiments assessed how people convert between relative frequencies, decimals, and displays of dots that denote very low proportions (i.e., proportions below 1%). The participants demonstrated perceptual, response, and numerical transformation biases. Furthermore, the data suggest that relative frequencies and decimals are associated with different abstract representations of amount. Scientists and lay people use several numerical formats (i.e., any symbol system used to represent quantities) to symbolize propor-tions. For example, the decimal “0.5 ” and relative frequency “1 in 2 ” symbolize the same proportion. Although relative frequencies and decimals denote proportions equally well, people may inter-pret these numerical formats differently. Nevertheless, researchers often make an implicit assumption that people interpret these numerical formats equivalently (termed the assumption of numer-ical equivalence). The implicit assumption of numerical equiva-lence is prevalent in studies of psychophysics (e.g., Gescheider
N=(1,1) super Yang--Mills theory in 1+1 dimensions at finite temperature
We present a formulation of N=(1,1) super Yang-Mills theory in 1+1 dimensions
at finite temperature. The partition function is constructed by finding a
numerical approximation to the entire spectrum. We solve numerically for the
spectrum using Supersymmetric Discrete Light-Cone Quantization (SDLCQ) in the
large-N_c approximation and calculate the density of states. We find that the
density of states grows exponentially and the theory has a Hagedorn
temperature, which we extract. We find that the Hagedorn temperature at
infinite resolution is slightly less than one in units of (g^(2) N_c/pi)^(1/2).
We use the density of states to also calculate a standard set of thermodynamic
functions below the Hagedorn temperature. In this temperature range, we find
that the thermodynamics is dominated by the massless states of the theory.Comment: 16 pages, 8 eps figures, LaTe
Traveling planetary-scale waves cause cloud variability on tidally locked aquaplanets
Cloud cover at the planetary limb of water-rich Earth-like planets is likely
to weaken chemical signatures in transmission spectra, impeding attempts to
characterize these atmospheres. However, based on observations of Earth and
solar system worlds, exoplanets with atmospheres should have both short-term
weather and long-term climate variability, implying that cloud cover may be
less during some observing periods. We identify and describe a mechanism
driving periodic clear sky events at the terminators in simulations of tidally
locked Earth-like planets. A feedback between dayside cloud radiative effects,
incoming stellar radiation and heating, and the dynamical state of the
atmosphere, especially the zonal wavenumber-1 Rossby wave identified in past
work on tidally locked planets, leads to oscillations in Rossby wave phase
speeds and in the position of Rossby gyres and results in advection of clouds
to or away from the planet's eastern terminator. We study this oscillation in
simulations of Proxima Centauri b, TRAPPIST 1-e, and rapidly rotating versions
of these worlds located at the extreme inner edge of their stars' habitable
zones. We simulate time series of the transit depths of the 1.4 {\mu}m water
feature and 2.7 {\mu}m carbon dioxide feature. The impact of atmospheric
variability on the transmission spectra is sensitive to the structure of the
dayside cloud cover and the location of the Rossby gyres, but none of our
simulations have variability significant enough to be detectable with current
methods.Comment: 21 pages, 11 figure
What is the effect of a decision aid in potentially vulnerable parents? Insights from the head CT choice randomized trial.
ObjectiveTo test the hypotheses that use of the Head CT Choice decision aid would be similarly effective in all parent/patient dyads but parents with high (vs low) numeracy experience a greater increase in knowledge while those with low (vs high) health literacy experience a greater increase in trust.MethodsThis was a secondary analysis of a cluster randomized trial conducted at seven sites. One hundred seventy-two clinicians caring for 971 children at intermediate risk for clinically important traumatic brain injuries were randomized to shared decision making facilitated by the DA (n = 493) or to usual care (n = 478). We assessed for subgroup effects based on patient and parent characteristics, including socioeconomic status (health literacy, numeracy and income). We tested for interactions using regression models with indicators for arm assignment and study site.ResultsThe decision aid did not increase knowledge more in parents with high numeracy (P for interaction [Pint ] = 0.14) or physician trust more in parents with low health literacy (Pint = 0.34). The decision aid decreased decisional conflict more in non-white parents (decisional conflict scale, -8.14, 95% CI: -12.33 to -3.95; Pint = 0.05) and increased physician trust more in socioeconomically disadvantaged parents (trust in physician scale, OR: 8.59, 95% CI: 2.35-14.83; Pint = 0.04).ConclusionsUse of the Head CT Choice decision aid resulted in less decisional conflict in non-white parents and greater physician trust in socioeconomically disadvantaged parents. Decision aids may be particularly effective in potentially vulnerable parents
Home-based HIV counseling and testing as a gateway to earlier initiation of antiretroviral therapy
Relationship Between A1C and Glucose Levels in the General Dutch Population: The New Hoorn Study
Chandra spectroscopy of the hot star beta Crucis and the discovery of a pre-main-sequence companion
In order to test the O star wind-shock scenario for X-ray production in less
luminous stars with weaker winds, we made a pointed 74 ks observation of the
nearby early B giant, beta Cru (B0.5 III), with the Chandra HETGS. We find that
the X-ray spectrum is quite soft, with a dominant thermal component near 3
million K, and that the emission lines are resolved but quite narrow, with
half-widths of 150 km/s. The forbidden-to-intercombination line ratios of Ne IX
and Mg XI indicate that the hot plasma is distributed in the wind, rather than
confined near the photosphere. It is difficult to understand the X-ray data in
the context of the standard wind-shock paradigm for OB stars, primarily because
of the narrow lines, but also because of the high X-ray production efficiency.
A scenario in which the bulk of the outer wind is shock heated is broadly
consistent with the data, but not very well motivated theoretically. It is
possible that magnetic channeling could explain the X-ray properties, although
no field has been detected on beta Cru. We detected periodic variability in the
hard (hnu > 1 keV) X-rays, modulated on the known optical period of 4.58 hours,
which is the period of the primary beta Cep pulsation mode for this star. We
also have detected, for the first time, an apparent companion to beta Cru at a
projected separation of 4 arcsec. This companion was likely never seen in
optical images because of the presumed very high contrast between it and beta
Cru in the optical. However, the brightness contrast in the X-ray is only 3:1,
which is consistent with the companion being an X-ray active low-mass
pre-main-sequence star. The companion's X-ray spectrum is relatively hard and
variable, as would be expected from a post T Tauri star.Comment: Accepted for publication in MNRAS; 19 pages, 15 figures, some in
color; version with higher-resolution figures available at
http://astro.swarthmore.edu/~cohen/papers/bcru_mnras2008.pd
Explaining the rise of 'human rights' in analyses of Sino-African relations
Popular perceptions of China and its global role are often shaped by two words: 'made in'. Yet this vision of China that focuses primarily on Beijing as a coming economic superpower is relatively new, and it is not that long ago that two other words tended to dominate debates on and discourses of China: 'human rights'. To be sure, real interest in human rights in China was never the only issue in other states' relations with China, nor consistently pursued throughout the years (Nathan, 1994). Nor did human rights totally subsequently disappear from the political agenda.1 Nevertheless, the rhetorical importance of human rights - perhaps best epitomised by the narrow defeat of resolutions condemning Chinese policy in 1995 at the Human Rights Council in Geneva - stands in stark contrast to the relative silence thereafter as the bottom line of most states' relations with Beijing took on ever greater economic dimensions
Estimated Average Glucose and Self-Monitored Mean Blood Glucose Are Discordant Estimates of Glycemic Control
- …