2,943 research outputs found
The snail-killing flies of Alaska (Diptera: Sciomyzidae)
Information is given on the geographic distribution, habitat preferences, larval foods, and immature stages for 57 species of 9 genera of Sciomyzidae known to occur in Alaska. An illustrated key to adults is included. Alaska as a habitat for sciomyzid flies is discussed, and information on feeding habits of the larvae is summarized
The Affective Impact of Financial Skewness on Neural Activity and Choice
Few finance theories consider the influence of âskewnessâ (or large and asymmetric but unlikely outcomes) on financial choice. We investigated the impact of skewed gambles on subjects' neural activity, self-reported affective responses, and subsequent preferences using functional magnetic resonance imaging (FMRI). Neurally, skewed gambles elicited more anterior insula activation than symmetric gambles equated for expected value and variance, and positively skewed gambles also specifically elicited more nucleus accumbens (NAcc) activation than negatively skewed gambles. Affectively, positively skewed gambles elicited more positive arousal and negatively skewed gambles elicited more negative arousal than symmetric gambles equated for expected value and variance. Subjects also preferred positively skewed gambles more, but negatively skewed gambles less than symmetric gambles of equal expected value. Individual differences in both NAcc activity and positive arousal predicted preferences for positively skewed gambles. These findings support an anticipatory affect account in which statistical properties of gamblesâincluding skewnessâcan influence neural activity, affective responses, and ultimately, choice
Spitzer/MIPS 24 ÎŒm Observations of HD 209458b: Three Eclipses, Two and a Half Transits, and a Phase Curve Corrupted by Instrumental Sensitivity Variations
We report the results of an analysis of all Spitzer/MIPS 24 ÎŒm observations of HD 209458b, one of the touchstone objects in the study of irradiated giant planet atmospheres. Altogether, we analyze two and a half transits, three eclipses, and a 58 hr near-continuous observation designed to detect the planet's thermal phase curve. The results of our analysis are: (1) a mean transit depth of 1.484% ± 0.033%, consistent with previous measurements and showing no evidence of variability in transit depth at the 3% level. (2) A mean eclipse depth of 0.338% ± 0.026%, somewhat higher than that previously reported for this system; this new value brings observations into better agreement with models. From this eclipse depth we estimate an average dayside brightness temperature of 1320 ± 80 K; the dayside flux shows no evidence of variability at the 12% level. (3) Eclipses in the system occur 32 ± 129 s earlier than would be expected from a circular orbit, which constrains the orbital quantity ecos Ï to be 0.00004 ± 0.00033. This result is fully consistent with a circular orbit and sets an upper limit of 140 m s^(â1) (3Ï) on any eccentricity-induced velocity offset during transit. The phase curve observations (including one of the transits) exhibit an anomalous trend similar to the detector ramp seen in previous Spitzer/IRAC observations; by modeling this ramp we recover the system parameters for this transit. The long-duration photometry which follows the ramp and transit exhibits a gradual ~0.2% decrease in flux over ~30 hr. This effect is similar to that seen in pre-launch calibration data taken with the 24 ÎŒm array and is better fit by an instrumental model than a model invoking planetary emission. The large uncertainties associated with this poorly understood, likely instrumental effect prevent us from usefully constraining the planet's thermal phase curve. Our observations highlight the need for a thorough understanding of detector-related instrumental effects on long timescales when making the high-precision mid-infrared measurements planned for future missions such as EChO, SPICA, and the James Webb Space Telescope
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TWRS information locator database system design description
This document gives an overview and description of the Tank Waste Remediation System (TWRS) Information Locator Database (ILD)system design. The TWRS ILD system is an inventory of information used in the TWRS Systems Engineering process to represent the TWRS Technical Baseline. The inventory is maintained in the form of a relational database developed in Paradox 4.5
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Sensitivity analysis of potential events affecting the double-shell tank system and fallback actions
Sensitivity analyses were performed for fall-back positions (i.e., management actions) to accommodate potential off-normal and programmatic change events overlaid on the waste volume projections and their uncertainties. These sensitivity analyses allowed determining and ranking tank system high-risk parameters and fall- back positions that will accommodate the respective impacts. This quantification of tank system impacts shows periods where tank capacity is sensitive to certain variables that must be carefully managed and/or evaluated. Identifying these sensitive variables and quantifying their impact will allow decision makers to prepare fall-back positions and focus available resources on the highest impact parameters where technical data are needed to reduce waste projection uncertainties. For noncomplexed waste, the period of capacity vulnerability occurs during the years of single-shell tank (SST) retrieval (after approximately 2009) due to the sensitivity to several variables. Ranked by importance these variables include the pretreatment rate and 200-East SST solids transfer volume. For complexed waste, the period of capacity vulnerability occurs during the period after approximately 2005 due to the sensitivity to several variables. Ranked by importance these variables include the pretreatment rate. 200-East SST solids transfer volume. complexed waste reduction factor using evaporation, and 200-west saltwell liquid porosity
The 8 Micron Phase Variation of the Hot Saturn HD 149026b
We monitor the star HD 149026 and its Saturn-mass planet at 8.0 micron over
slightly more than half an orbit using the Infrared Array Camera (IRAC) on the
Spitzer Space Telescope. We find an increase of 0.0227% +/- 0.0066% (3.4 sigma
significance) in the combined planet-star flux during this interval. The
minimum flux from the planet is 45% +/- 19% of the maximum planet flux,
corresponding to a difference in brightness temperature of 480 +/- 140 K
between the two hemispheres. We derive a new secondary eclipse depth of 0.0411%
+/- 0.0076% in this band, corresponding to a dayside brightness temperature of
1440 +/- 150 K. Our new secondary eclipse depth is half that of a previous
measurement (3.0 sigma difference) in this same bandpass by Harrington et al.
(2007). We re-fit the Harrington et al. (2007) data and obtain a comparably
good fit with a smaller eclipse depth that is consistent with our new value. In
contrast to earlier claims, our new eclipse depth suggests that this planet's
dayside emission spectrum is relatively cool, with an 8 micron brightness
temperature that is less than the maximum planet-wide equilibrium temperature.
We measure the interval between the transit and secondary eclipse and find that
that the secondary eclipse occurs 20.9 +7.2 / -6.5 minutes earlier (2.9 sigma)
than predicted for a circular orbit, a marginally significant result. This
corresponds to e*cos(omega) = -0.0079 +0.0027 / -0.0025 where e is the planet's
orbital eccentricity and omega is the argument of pericenter.Comment: 17 pages, 12 figure, accepted for publication in Ap
From Service to Experience: Understanding and Defining the Hospitality Business
Failure adequately to define or understand hospitality as a commercial phenomenon has created a fragmented academic environment and a schizophrenia in the industry that has the potential to limit its development as a global industry. This article suggests that, by redefining hospitality as behaviour and experience, a new perspective emerges that has exciting implications for the management of hospitality businesses. A framework to describe hospitality in the commercial domain is proposed. This framework suggests a focus on the hostâguest relationship, generosity, theatre and performance, âlots of little surprisesâ, and the security of strangers â a focus that provides guests with experiences that are personal, memorable and add value to their lives
Transiting Exoplanet Studies and Community Targets for JWST's Early Release Science Program
The James Webb Space Telescope (JWST) will likely revolutionize transiting exoplanet atmospheric science, due to a combination of its capability for continuous, long duration observations and its larger collecting area, spectral coverage, and spectral resolution compared to existing space-based facilities. However, it is unclear precisely how well JWST will perform and which of its myriad instruments and observing modes will be best suited for transiting exoplanet studies. In this article, we describe a prefatory JWST Early Release Science (ERS) Cycle 1 program that focuses on testing specific observing modes to quickly give the community the data and experience it needs to plan more efficient and successful transiting exoplanet characterization programs in later cycles. We propose a multi-pronged approach wherein one aspect of the program focuses on observing transits of a single target with all of the recommended observing modes to identify and understand potential systematics, compare transmission spectra at overlapping and neighboring wavelength regions, confirm throughputs, and determine overall performances. In our search for transiting exoplanets that are well suited to achieving these goals, we identify 12 objects (dubbed "community targets") that meet our defined criteria. Currently, the most favorable target is WASP-62b because of its large predicted signal size, relatively bright host star, and location in JWST's continuous viewing zone. Since most of the community targets do not have well-characterized atmospheres, we recommend initiating preparatory observing programs to determine the presence of obscuring clouds/hazes within their atmospheres. Measurable spectroscopic features are needed to establish the optimal resolution and wavelength regions for exoplanet characterization. Other initiatives from our proposed ERS program include testing the instrument brightness limits and performing phase-curve observations. The latter are a unique challenge compared to transit observations because of their significantly longer durations. Using only a single mode, we propose to observe a full-orbit phase curve of one of the previously characterized, short-orbital-period planets to evaluate the facility-level aspects of long, uninterrupted time-series observations
Quark Coulomb Interactions and the Mass Difference of Mirror Nuclei
We study the Okamoto-Nolen-Schiffer (ONS) anomaly in the binding energy of
mirror nuclei at high density by adding a single neutron or proton to a quark
gluon plasma. In this high-density limit we find an anomaly equal to two-thirds
of the Coulomb exchange energy of a proton. This effect is dominated by quark
electromagnetic interactions---rather than by the up-down quark mass
difference. At normal density we calculate the Coulomb energy of neutron matter
using a string-flip quark model. We find a nonzero Coulomb energy because of
the neutron's charged constituents. This effect could make a significant
contribution to the ONS anomaly.Comment: 4 pages, 2 figs. sub. to Phys. Rev. Let
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