3,672 research outputs found
The Competitive Causes and Consequences of Customer Satisfaction
We conduct two studies to test three hypotheses: (1) Competition increases a firm's customer satisfaction; (2) Rivals' customer satisfaction increases a firm's customer satisfaction; (3) Rivals' customer satisfaction reduces a firm's sales. First, we use store-level customer satisfaction data from a supermarket chain. Next, we consider a range of industries, using brand-level customer satisfaction ratings from the American Customer Satisfaction Index. Results from both studies provide support for the latter two hypotheses, while we only find support for the first hypothesis in the second study.Customer Satisfaction, Food retailing, Competitive Strategy, Consumer/Household Economics,
Mexico-UK Sub-millimeter Camera for AsTronomy
MUSCAT is a large format mm-wave camera scheduled for installation on the
Large Millimeter Telescope Alfonso Serrano (LMT) in 2018. The MUSCAT focal
plane is based on an array of horn coupled lumped-element kinetic inductance
detectors optimised for coupling to the 1.1mm atmospheric window. The detectors
are fed with fully baffled reflective optics to minimize stray-light
contamination. This combination will enable background-limited performance at
1.1 mm across the full 4 arcminute field-of-view of the LMT. The easily
accessible focal plane will be cooled to 100 mK with a new closed cycle
miniature dilution refrigerator that permits fully continuous operation. The
MUSCAT instrument will demonstrate the science capabilities of the LMT through
two relatively short science programmes to provide high resolution follow-up
surveys of Galactic and extra-galactic sources previously observed with the
Herschel space observatory, after the initial observing campaigns. In this
paper, we will provide an overview of the overall instrument design as well as
an update on progress and scheduled installation on the LMT.Comment: Accepted for publication in the Journal of Low Temperature Detector
Development of a myco-material based on textile and agro-industrial waste for thermal insulation
The European Union is promoting the increased use of thermal insulation to ensure energy conservation in the coming years. This will drive increased demand for materials suitable for such applications. However, the rise in the production of goods combined with the prevalent use of non-renewable resources in thermal insulation pose environmental challenges, leading to increased pollution and solid waste accumulation. In response, this study focuses on developing and characterizing a sustainable, biodegradable mycelium-based composite for thermal insulation. The bio-composite, cultivated from Pleurotus Pulmonarius fungus in agro-industrial and textile waste, offers a promising approach. In this work, two distinct combinations of substrates were utilized: one comprising 70% grass cuttings and dry leaves, along with 30% recycled ground textile, predominantly polyester; the other consisting of 70% sugarcane bagasse and 30% ground textile waste. Additionally, an extra 20% of the substrate weight of Pleurotus Ostreatus grain spawn was added to each combination to facilitate mycelium growth. The mycomaterials were tested for tensile and compression analysis (ASTM D3039 and ASTM D695 standards, respectively) and a thermal conductivity assessment (ISO 8301) was done. The materials showed better performance at compression tests than tensile test. Also, results demonstrate the superior performance of sugarcane bagasse mycelium composites over the dry leaves/grass cutting counterparts in thermal conductivity, tensile and compression tests. The inclusion of synthetic fibres to the mycelium composite may have compromised the mechanical and thermal properties of the samples as polyester fibres have a higher thermal conductivity than the natural components included in the sample. The fibres being synthetic, the mycelium could not feed on it, thus impeding binding and proliferation in some sections of the material
Cosmological Simulations with Self-Interacting Dark Matter I: Constant Density Cores and Substructure
We use cosmological simulations to study the effects of self-interacting dark
matter (SIDM) on the density profiles and substructure counts of dark matter
halos from the scales of spiral galaxies to galaxy clusters, focusing
explicitly on models with cross sections over dark matter particle mass
\sigma/m = 1 and 0.1 cm^2/g. Our simulations rely on a new SIDM N-body
algorithm that is derived self-consistently from the Boltzmann equation and
that reproduces analytic expectations in controlled numerical experiments. We
find that well-resolved SIDM halos have constant-density cores, with
significantly lower central densities than their CDM counterparts. In contrast,
the subhalo content of SIDM halos is only modestly reduced compared to CDM,
with the suppression greatest for large hosts and small halo-centric distances.
Moreover, the large-scale clustering and halo circular velocity functions in
SIDM are effectively identical to CDM, meaning that all of the large-scale
successes of CDM are equally well matched by SIDM. From our largest cross
section runs we are able to extract scaling relations for core sizes and
central densities over a range of halo sizes and find a strong correlation
between the core radius of an SIDM halo and the NFW scale radius of its CDM
counterpart. We construct a simple analytic model, based on CDM scaling
relations, that captures all aspects of the scaling relations for SIDM halos.
Our results show that halo core densities in \sigma/m = 1 cm^2/g models are too
low to match observations of galaxy clusters, low surface brightness spirals
(LSBs), and dwarf spheroidal galaxies. However, SIDM with \sigma/m ~ 0.1 cm^2/g
appears capable of reproducing reported core sizes and central densities of
dwarfs, LSBs, and galaxy clusters without the need for velocity dependence.
(abridged)Comment: 26 pages, 16 figures, all figures include colors, submitted for
publication in MNRA
Distinct DNA methylomes of newborns and centenarians
Human aging cannot be fully understood in terms of the constrained genetic setting. Epigenetic drift is an alternative means of explaining age-associated alterations. To address this issue, we performed whole-genome bisulfite sequencing (WGBS) of newborn and centenarian genomes. The centenarian DNA had a lower DNA methylation content and a reduced correlation in the methylation status of neighboring cytosine--phosphate--guanine (CpGs) throughout the genome in comparison with the more homogeneously methylated newborn DNA. The more hypomethylated CpGs observed in the centenarian DNA compared with the neonate covered all genomic compartments, such as promoters, exonic, intronic, and intergenic regions. For regulatory regions, the most hypomethylated sequences in the centenarian DNA were present mainly at CpG-poor promoters and in tissue-specific genes, whereas a greater level of DNA methylation was observed in CpG island promoters. We extended the study to a larger cohort of newborn and nonagenarian samples using a 450,000 CpG-site DNA methylation microarray that reinforced the observation of more hypomethylated DNA sequences in the advanced age group. WGBS and 450,000 analyses of middle-age individuals demonstrated DNA methylomes in the crossroad between the newborn and the nonagenarian/centenarian groups. Our study constitutes a unique DNA methylation analysis of the extreme points of human life at a single-nucleotide resolution level
Grupo español de cirugĂa torĂĄcica asistida por videoimagen: mĂ©todo, auditorĂa y resultados iniciales de una cohorte nacional prospectiva de pacientes tratados con resecciones anatĂłmicas del pulmĂłn
Introduction: our study sought to know the current implementation of video-assisted thoracoscopic surgery (VATS) for anatomical lung resections in Spain. We present our initial results and describe the auditing systems developed by the Spanish VATS Group (GEVATS). Methods: we conducted a prospective multicentre cohort study that included patients receiving anatomical lung resections between 12/20/2016 and 03/20/2018. The main quality controls consisted of determining the recruitment rate of each centre and the accuracy of the perioperative data collected based on six key variables. The implications of a low recruitment rate were analysed for '90-day mortality' and 'Grade IIIb-V complications'. Results: the series was composed of 3533 cases (1917 VATS; 54.3%) across 33 departments. The centres' median recruitment rate was 99% (25-75th:76-100%), with an overall recruitment rate of 83% and a data accuracy of 98%. We were unable to demonstrate a significant association between the recruitment rate and the risk of morbidity/mortality, but a trend was found in the unadjusted analysis for those centres with recruitment rates lower than 80% (centres with 95-100% rates as reference): grade IIIb-V OR=0.61 (p=0.081), 90-day mortality OR=0.46 (p=0.051). Conclusions: more than half of the anatomical lung resections in Spain are performed via VATS. According to our results, the centre's recruitment rate and its potential implications due to selection bias, should deserve further attention by the main voluntary multicentre studies of our speciality. The high representativeness as well as the reliability of the GEVATS data constitute a fundamental point of departure for this nationwide cohort
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy
We measure the energy emitted by extensive air showers in the form of radio
emission in the frequency range from 30 to 80 MHz. Exploiting the accurate
energy scale of the Pierre Auger Observatory, we obtain a radiation energy of
15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV
arriving perpendicularly to a geomagnetic field of 0.24 G, scaling
quadratically with the cosmic-ray energy. A comparison with predictions from
state-of-the-art first-principle calculations shows agreement with our
measurement. The radiation energy provides direct access to the calorimetric
energy in the electromagnetic cascade of extensive air showers. Comparison with
our result thus allows the direct calibration of any cosmic-ray radio detector
against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI.
Supplemental material in the ancillary file
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in
operation since July 2014. This paper describes the second data release from
this phase, and the fourteenth from SDSS overall (making this, Data Release
Fourteen or DR14). This release makes public data taken by SDSS-IV in its first
two years of operation (July 2014-2016). Like all previous SDSS releases, DR14
is cumulative, including the most recent reductions and calibrations of all
data taken by SDSS since the first phase began operations in 2000. New in DR14
is the first public release of data from the extended Baryon Oscillation
Spectroscopic Survey (eBOSS); the first data from the second phase of the
Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2),
including stellar parameter estimates from an innovative data driven machine
learning algorithm known as "The Cannon"; and almost twice as many data cubes
from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous
release (N = 2812 in total). This paper describes the location and format of
the publicly available data from SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken (both
targeting and observation details) and processed for scientific use. The SDSS
website (www.sdss.org) has been updated for this release, and provides links to
data downloads, as well as tutorials and examples of data use. SDSS-IV is
planning to continue to collect astronomical data until 2020, and will be
followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14
happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov
2017 (this is the "post-print" and "post-proofs" version; minor corrections
only from v1, and most of errors found in proofs corrected
A chemical survey of exoplanets with ARIEL
Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planetâs birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25â7.8 ÎŒm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10â100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed â using conservative estimates of mission performance and a full model of all significant noise sources in the measurement â using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL â in line with the stated mission objectives â will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio
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