195 research outputs found
Short Gamma-Ray Bursts with Extended Emission Observed with Swift/BAT and Fermi/GBM
Some short GRBs are followed by longer extended emission, lasting anywhere
from ~10 to ~100 s. These short GRBs with extended emission (EE) can possess
observational characteristics of both short and long GRBs (as represented by
GRB 060614), and the traditional classification based on the observed duration
places some of them in the long GRB class. While GRBs with EE pose a challenge
to the compact binary merger scenario, they may therefore provide an important
link between short and long duration events. To identify the population of GRBs
with EE regardless of their initial classifications, we performed a systematic
search of short GRBs with EE using all available data (up to February 2013) of
both Swift/BAT and Fermi/GBM. The search identified 16 BAT and 14 GBM detected
GRBs with EE, several of which are common events observed with both detectors.
We investigated their spectral and temporal properties for both the spikes and
the EE, and examined correlations among these parameters. Here we present the
results of the systematic search as well as the properties of the identified
events. Finally, their properties are also compared with short GRBs with EE
observed with BATSE, identified through our previous search effort. We found
several strong correlations among parameters, especially when all of the
samples were combined. Based on our results, a possible progenitor scenario of
two-component jet is discussed.Comment: Published in MNRAS; matched to the published versio
Superheated water extraction of essential oils of Origanum micranthum
Superheated water extraction is used to extract essential oil of leaves of Origanum micranthum. The effect of different temperatures on the essential oil profile and rate of extraction as a function of time is investigated. The components of essential oil of Origanum micranthum are removed from the aqueous extract by C18 solid-phase extraction. The identification of components is carried out using comprehensive gas chromatography-time of flight-mass spectrometry. The number of extracted components is almost the same; however, the concentrations change with changing temperature. The highest yield (0.64%) is found at a temperature of 150°C, 2 mL/min and 60 bar for 30 min. The increasing temperature from 100°C to 175°C increased the rate of extraction of six selected components of essential oil of Origanum micranthum. cis-Sabinenehydrate exhibits the fastest rate of extraction at all temperatures studied. Some degradation products are observed at a temperature of 175°C
The influence of early efficacy beliefs on teams' reactions to failing to reach performance goals
Cataloged from PDF version of article.Although a considerable amount of theoretical and empirical attention has been devoted to understanding individuals' responses to goal–performance discrepancies (GPDs), little attention has been devoted to examining how teams respond to GPDs. The present research sought to examine how teams responded to negative GPDs. We predicted that failing to reach higher goals would be perceived as less negative than failing to reach lower goals, and we examined the moderating influence of setting higher versus lower goals on how teams responded to performance that fell short of those goals. We also examined the role that efficacy beliefs that were formed early in those teams played in further explaining these effects. Results from 94 teams who all failed to reach self-set goals revealed that teams that failed to reach higher goals downwardly revised their goals less than teams that failed to reach lower goals. Early efficacy beliefs further explained these effects. High efficacy beliefs lessened the negative effects of failing to reach lower goals on subsequent goals. High efficacy beliefs also lessened the negative effects of failing to reach higher goals while low efficacy beliefs strengthened the negative effects of failing to reach higher goals. The implications of these findings for theory, research, and practice are discussed
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Microwave-dried or air-dried? Consumers' stated preferences and attitudes for organic dried strawberries. A multi-country investigation in Europe
Non-thermal food processing technologies are becoming more important in the organic food sector because, beyond preserving the organic feature, they could offer organic products with additional benefits in terms of enhanced nutritional content and healthiness as well as better sensory properties that could satisfy the more complex demands of organic consumers. Berries have a well-known health benefits and show increasing market shares in European markets while dehydration can increase the food convenience in terms of extended shelf-life. This study investigates for the first time organic consumers' stated preferences, attitudes and individual differences for a non-thermal organic processing technology. Specifically, we investigated consumers' preferences for organic dried strawberries varying in drying technology used, such as the most conventional (i.e. thermal) air drying and the most innovative (i.e. non-thermal) microwave drying, origin, price levels, and nutrient contents in three European countries: Norway, Romania and Turkey. Data from a total of 614 consumers were collected through an online choice experiment. Results show that on average consumers prefer organic dried strawberries produced with air drying technology that have national origin, with natural nutrient content and at low price, but country and individual differences are identified. Consumers who showed least rejection for microwave dried products are young, mostly from Norway and have higher positive attitudes towards new food technologies. Consumers who showed most rejection for microwave dried products are older, mostly from Turkey and have higher positive attitudes for organic, natural and ecological products. Organic producers who adopt microwave drying might better inform consumers about the characteristics, the process and highlight the nutritional benefits of such technology. Finally, this research informs policy makers about the need to define and regulate more clearly microwave drying as an organic technology, as well as to regulate labelling to ensure that consumers are not misled and correctly informed about the new technology
When does teamwork translate into improved team performance? a resource allocation perspective
Drawing on resource allocation theory, the authors examined boundary conditions for the positive effects of two aspects of teamwork (backing up behavior and performance monitoring) on team performance. Participants were 276 undergraduate business students who were organized into 69 teams and who worked on a computer simulation across multiple performance episodes. Approximately half the teams experienced a workload distribution problem. Results indicated that performance monitoring had positive effects on team performance when teams experienced a workload distribution problem. Backing up behavior had positive effects only when teams had both a workload distribution problem and during early performance episodes. The findings of this study suggest that resource allocation theory can provide insights regarding when members should devote and coordinate their own individual resources to assist others in teams. The implications of these findings for future theory and practice regarding teamwork are discussed. © The Author(s) 2010
Does backing up behavior explain the efficacy-performance relationship in teams?
Although the relationship between collective efficacy beliefs and team performance has been well-documented, few studies have explored the causal mechanisms that might explain these effects. In the current study, the authors explore the role of backing up behavior, a specific form of teamwork behavior, in explaining why high efficacy beliefs lead to high levels of team performance. Participants were 416 undergraduate business students who were organized into 104 four-person teams. The teams worked on an interdependent, computerized, decision-making task. Results of the study revealed that collective efficacy beliefs were positively related to team performance and that backing up behaviors largely mediated these effects. The theoretical and practical implications of these findings are discussed. © The Author(s) 2011
John Schuster, Descartes-agonistes: Physico-mathematics, method and corpuscular-mechanism, 1618–1633
We report on a 10 ks simultaneous Chandra/HETG-NuSTAR observation of the
Bursting Pulsar, GRO J1744-28, during its third detected outburst since
discovery and after nearly 18 years of quiescence. The source is detected up to
60 keV with an Eddington persistent flux level. Seven bursts, followed by dips,
are seen with Chandra, three of which are also detected with NuSTAR. Timing
analysis reveals a slight increase in the persistent emission pulsed fraction
with energy (from 10% to 15%) up to 10 keV, above which it remains constant.
The 0.5-70 keV spectra of the persistent and dip emission are the same within
errors, and well described by a blackbody (BB), a power-law with an exponential
rolloff, a 10 keV feature, and a 6.7 keV emission feature, all modified by
neutral absorption. Assuming that the BB emission originates in an accretion
disc, we estimate its inner (magnetospheric) radius to be about 4x10^7 cm,
which translates to a surface dipole field B~9x10^10 G. The Chandra/HETG
spectrum resolves the 6.7 keV feature into (quasi-)neutral and highly ionized
Fe XXV and Fe XXVI emission lines. XSTAR modeling shows these lines to also
emanate from a truncated accretion disk. The burst spectra, with a peak flux
more than an order of magnitude higher than Eddington, are well fit with a
power-law with an exponential rolloff and a 10~keV feature, with similar fit
values compared to the persistent and dip spectra. The burst spectra lack a
thermal component and any Fe features. Anisotropic (beamed) burst emission
would explain both the lack of the BB and any Fe components.Comment: 15 pages, 11 figures, Accepted in Ap
The Dark Side of ROTSE-III Prompt GRB Observations
We present several cases of optical observations during gamma-ray bursts
(GRBs) which resulted in prompt limits but no detection of optical emission.
These limits constrain the prompt optical flux densities and the optical
brightness relative to the gamma-ray emission. The derived constraints fall
within the range of properties observed in GRBs with prompt optical detections,
though at the faint end of optical/gamma flux ratios. The presently accessible
prompt optical limits do not require a different set of intrinsic or
environmental GRB properties, relative to the events with prompt optical
detections.Comment: ApJ accepted. 20 pages in draft manuscript form, which includes 6
pages of tables and 2 figure
Chandra Observations of the Anomalous X-ray Pulsar 1E 2259+58.6
We present X-ray imaging, timing, and phase resolved spectroscopy of the anomalous X-ray pulsar 1E 2259+58.6 using the Chandra X-ray Observatory. The spectrum is well described by a power law plus blackbody model with power law index = 3.6(1), kT_BB = 0.412(6) keV, and N_H=0.93(3) x 10^{22} cm^{-2}; we find no evidence for spectral features (0.5-7.0 keV). We derive a new, precise X-ray position for the source and determine its spin period, P=6.978977(24) s. Time resolved X-ray spectra show no significant variation as a function of pulse phase. We have detected excess emission beyond 4 arcsec from the central source extending to beyond 100 arcsec, due to the supernova remnant and possibly dust scattering from the interstellar medium
Status of the ROTSE-III telescope network
ROTSE-III is a homogeneous worldwide array of 4 robotic telescopes. They were designed to provide optical observations of γ-ray burst (GRB) afterglows as close as possible to the start of γ-ray emission. ROTSE-III is fulfilling its potential for GRB science, and provides optical observations for a variety of astrophysical sources in the interim between GRB events
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