124 research outputs found
Photometry and Spectroscopy of GRB 030329 and Its Associated Supernova 2003dh: The First Two Months
We present extensive optical and infrared photometry of the afterglow of
gamma-ray burst (GRB) 030329 and its associated supernova (SN) 2003dh over the
first two months after detection (2003 March 30-May 29 UT). Optical
spectroscopy from a variety of telescopes is shown and, when combined with the
photometry, allows an unambiguous separation between the afterglow and
supernova contributions. The optical afterglow of the GRB is initially a
power-law continuum but shows significant color variations during the first
week that are unrelated to the presence of a supernova. The early afterglow
light curve also shows deviations from the typical power-law decay. A supernova
spectrum is first detectable ~7 days after the burst and dominates the light
after ~11 days. The spectral evolution and the light curve are shown to closely
resemble those of SN 1998bw, a peculiar Type Ic SN associated with GRB 980425,
and the time of the supernova explosion is close to the observed time of the
GRB. It is now clear that at least some GRBs arise from core-collapse SNe.Comment: 57 pages, 13 figures, accepted by ApJ, revised per referee's
comments, includes full photometry table. Data available at
ftp://cfa-ftp.harvard.edu/pub/kstanek/GRB030329 or through WWW at
http://cfa-www.harvard.edu/cfa/oir/Research/GRB
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The NEID precision radial velocity spectrometer: Commissioning of the Port Adapter
In October 2019, the NEID instrument (PI Suvrath Mahadevan, PSU) was delivered to the WIYN 3.5 m Telescope at Kitt Peak National Observatory. Commissioning began shortly after delivery, but was paused due to a COVID-19 imposed observatory shutdown in March 2020. The observatory has recently reopened and NEID commissioning has resumed. NEID is an optical (380-930 nm), fiber-fed, precision Doppler radial velocity system developed as part of the NN-EXPLORE partnership. While the spectrometer and calibration system are maintained in a highly controlled environment on the basement level of the WIYN, the NEID Port Adapter mounts directly to a bent-Cassegrain port on the telescope and is responsible for precisely and stably placing target light on the science fibers. Here we present a brief overview of the as-built Port Adapter and its sub-components. We then discuss preliminary on-sky performance compared to requirements as well as next steps as we complete commissioning
The Role of Occupants in Buildings’ Energy Performance Gap: Myth or Reality?
Buildings’ expected (projected, simulated) energy use frequently does not match actual observations. This is commonly referred to as the energy performance gap. As such, many factors can contribute to the disagreement between expectations and observations. These include, for instance, uncertainty about buildings’ geometry, construction, systems, and weather conditions. However, the role of occupants in the energy performance gap has recently attracted much attention. It has even been suggested that occupants are the main cause of the energy performance gap. This, in turn, has led to suggestions that better models of occupant behavior can reduce the energy performance gap. The present effort aims at the review and evaluation of the evidence for such claims. To this end, a systematic literature search was conducted and relevant publications were identified and reviewed in detail. The review entailed the categorization of the studies according to the scope and strength of the evidence for occupants’ role in the energy performance gap. Moreover, deployed calculation and monitoring methods, normalization procedures, and reported causes and magnitudes of the energy performance gap were documented and evaluated. The results suggest that the role of occupants as significant or exclusive contributors to the energy performance gap is not sufficiently substantiated by evidence.</jats:p
Stabilizing Salt-Bridge Enhances Protein Thermostability by Reducing the Heat Capacity Change of Unfolding
Most thermophilic proteins tend to have more salt bridges, and achieve higher thermostability by up-shifting and broadening their protein stability curves. While the stabilizing effect of salt-bridge has been extensively studied, experimental data on how salt-bridge influences protein stability curves are scarce. Here, we used double mutant cycles to determine the temperature-dependency of the pair-wise interaction energy and the contribution of salt-bridges to ΔCp in a thermophilic ribosomal protein L30e. Our results showed that the pair-wise interaction energies for the salt-bridges E6/R92 and E62/K46 were stabilizing and insensitive to temperature changes from 298 to 348 K. On the other hand, the pair-wise interaction energies between the control long-range ion-pair of E90/R92 were negligible. The ΔCp of all single and double mutants were determined by Gibbs-Helmholtz and Kirchhoff analyses. We showed that the two stabilizing salt-bridges contributed to a reduction of ΔCp by 0.8–1.0 kJ mol−1 K−1. Taken together, our results suggest that the extra salt-bridges found in thermophilic proteins enhance the thermostability of proteins by reducing ΔCp, leading to the up-shifting and broadening of the protein stability curves
The Scales Project, a cross-national dataset on the interpretation of thermal perception scales
Thermal discomfort is one of the main triggers for occupants’ interactions with components of the built environment such as adjustments of thermostats and/or opening windows and strongly related to the energy use in buildings. Understanding causes for thermal (dis-)comfort is crucial for design and operation of any type of building. The assessment of human thermal perception through rating scales, for example in post-occupancy studies, has been applied for several decades; however, long-existing assumptions related to these rating scales had been questioned by several researchers. The aim of this study was to gain deeper knowledge on contextual influences on the interpretation of thermal perception scales and their verbal anchors by survey participants. A questionnaire was designed and consequently applied in 21 language versions. These surveys were conducted in 57 cities in 30 countries resulting in a dataset containing responses from 8225 participants. The database offers potential for further analysis in the areas of building design and operation, psycho-physical relationships between human perception and the built environment, and linguistic analyses
The Adaptive Thermal Comfort Review from the 1920s, the Present, and the Future
The typical method for comfort analysis is the Predicted Mean Vote and Predicted Percentage Dissatisfied (PMV-PPD). However, they present limitations in accommodating the comfort of a disabled and elder group of people, which are the most vulnerable to climate change and energy poverty. The adaptive method can give flexibility and personalisation needed to overcome the problem due to the variability of the people's metabolism, historical and behavioural preferences. Investments to upgrade the indoor environmental quality and building design can then be effectively used and, for the first time, it will be possible to tailor the solutions for these particular groups of people. The adaptive approach uses Artificial Intelligence (AI), where it can introduce the imperfect learning process. Overcoming this, instead of going further for the Explainable AI, the PMV–PPD approach can be used for the learning validation and verification needed for the adaptive setting point and standards
Evaluating assumptions of scales for subjective assessment of thermal environments – Do laypersons perceive them the way, we researchers believe?
People's subjective response to any thermal environment is commonly investigated by using rating scales describing the degree of thermal sensation, comfort, and acceptability. Subsequent analyses of results collected in this way rely on the assumption that specific distances between verbal anchors placed on the scale exist and that relationships between verbal anchors from different dimensions that are assessed (e.g. thermal sensation and comfort) do not change. Another inherent assumption is that such scales are independent of the context in which they are used (climate zone, season, etc.). Despite their use worldwide, there is indication that contextual differences influence the way the scales are perceived and therefore question the reliability of the scales’ interpretation. To address this issue, a large international collaborative questionnaire study was conducted in 26 countries, using 21 different languages, which led to a dataset of 8225 questionnaires. Results, analysed by means of robust statistical techniques, revealed that only a subset of the responses are in accordance with the mentioned assumptions. Significant differences appeared between groups of participants in their perception of the scales, both in relation to distances of the anchors and relationships between scales. It was also found that respondents’ interpretations of scales changed with contextual factors, such as climate, season, and language. These findings highlight the need to carefully consider context-dependent factors in interpreting and reporting results from thermal comfort studies or post-occupancy evaluations, as well as to revisit the use of rating scales and the analysis methods used in thermal comfort studies to improve their reliability
The Scales Project, a cross-national dataset on the interpretation of thermal perception scales
Thermal discomfort is one of the main triggers for occupants' interactions with components of the built environment such as adjustments of thermostats and/or opening windows and strongly related to the energy use in buildings. Understanding causes for thermal (dis-)comfort is crucial for design and operation of any type of building. The assessment of human thermal perception through rating scales, for example in post-occupancy studies, has been applied for several decades; however, long-existing assumptions related to these rating scales had been questioned by several researchers. The aim of this study was to gain deeper knowledge on contextual influences on the interpretation of thermal perception scales and their verbal anchors by survey participants. A questionnaire was designed and consequently applied in 21 language versions. These surveys were conducted in 57 cities in 30 countries resulting in a dataset containing responses from 8225 participants. The database offers potential for further analysis in the areas of building design and operation, psycho-physical relationships between human perception and the built environment, and linguistic analyses
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