2,341 research outputs found
Rumor communities, social media, and forthcoming innovations: the shaping of technological frames in product market evolution
Technological frames provide an interpretive mechanism for individuals to evaluate new product innovations. These frames therefore play an important role in product market evolution. But how are technological frames themselves shaped? Prior research has demonstrated how technological frames are influenced by consumersā direct experience with new products and how they are informed by traditional media evaluations. More recently, however, the emergence of social media has resulted in the development of new arenas where consumers, producers, and other actors discuss and debate forthcoming product innovations by exchanging rumors and propositions. Integrating insights from the sociology of rumor and the affordances of social media, we propose a model of how online product rumor communities shape technological frames in a way not accounted for by prior models of innovation and product market evolution. Online product rumor communities influence product market evolution not only when products are released but also in the āprehistoryā of product markets
Level crossings and turning points of random hyperbolic polynomials
In this paper, we show that the asymptotic estimate for the expected number of K-level crossings of a random hyperbolic polynomial a1sinhx+a2sinh2x+āÆ+ansinhnx, where aj(j=1,2,ā¦,n) are independent normally distributed random variables with mean zero and variance one, is (1/Ļ)logn. This result is true for all K independent of x, provided Kā”Kn=O(n). It is also shown that the asymptotic estimate of the expected number of turning points for the random polynomial a1coshx+a2cosh2x+āÆ+ancoshnx, with aj(j=1,2,ā¦,n) as before, is also (1/Ļ)logn
Bacterial Mutagenicity of Urban Organic Aerosol Sources in Comparison to Atmospheric Samples
The bacterial mutagenicity of a comprehensive set of urban
particulate air pollution source samples is examined using
the Salmonella typhimurium forward mutation assay.
Each of the combustion source samples examined, including
the exhaust from catalyst-equipped autos, noncatalyst
autos, heavy-duty diesel trucks, plus natural gas, distillate oil, and wood combustion sources, is mutagenic in this assay, with a response per microgram of organic carbon in these samples generally greater than that of cigarette smoke aerosol. The noncombustion source samples tested generally are not mutagenic at the levels examined. The specific mutagenicity (mutant fraction per microgram of
organic carbon) of ambient aerosol samples collected in
southern California is compared to a weighted average of
the specific mutagenicity of the primary source samples
assembled in proportion to their emission rates in the Los
Angeles area. In most cases where a comparison can be
made, the specific mutagenicity of the source composites
and the ambient samples are of similar magnitude, with
the exception that the -PMS mutagenicity of the aerosol
at Long Beach, CA, during the first half of the calendar
year 1982 and at Azusa, CA, during the April-June 1982
period is much higher than can be explained by direct
emissions from the sources studied here
Analysis of ozone and nitric acid in spring and summer Arctic pollution using aircraft, ground-based, satellite observations and MOZART-4 model: source attribution and partitioning
In this paper, we analyze tropospheric O_3 together with HNO_3 during the POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport) program, combining observations and model results. Aircraft observations from the NASA ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) and NOAA ARCPAC (Aerosol, Radiation and Cloud Processes affecting Arctic Climate) campaigns during spring and summer of 2008 are used together with the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4) to assist in the interpretation of the observations in terms of the source attribution and transport of O_3 and HNO_3 into the Arctic (north of 60Ā° N). The MOZART-4 simulations reproduce the aircraft observations generally well (within 15%), but some discrepancies in the model are identified and discussed. The observed correlation of O_3 with HNO_3 is exploited to evaluate the MOZART-4 model performance for different air mass types (fresh plumes, free troposphere and stratospheric-contaminated air masses).
Based on model simulations of O_3 and HNO_3 tagged by source type and region, we find that the anthropogenic pollution from the Northern Hemisphere is the dominant source of O3 and HNO3 in the Arctic at pressures greater than 400 hPa, and that the stratospheric influence is the principal contribution at pressures less 400 hPa. During the summer, intense Russian fire emissions contribute some amount to the tropospheric columns of both gases over the American sector of the Arctic. North American fire emissions (California and Canada) also show an important impact on tropospheric ozone in the Arctic boundary layer.
Additional analysis of tropospheric O_3 measurements from ground-based FTIR and from the IASI satellite sounder made at the Eureka (Canada) and Thule (Greenland) polar sites during POLARCAT has been performed using the tagged contributions. It demonstrates the capability of these instruments for observing pollution at northern high latitudes. Differences between contributions from the sources to the tropospheric columns as measured by FTIR and IASI are discussed in terms of vertical sensitivity associated with these instruments. The first analysis of O_3 tropospheric columns observed by the IASI satellite instrument over the Arctic is also provided. Despite its limited vertical sensitivity in the lowermost atmospheric layers, we demonstrate that IASI is capable of detecting low-altitude pollution transported into the Arctic with some limitations
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Testing the performance of field calibration techniques for low-cost gas sensors in new deployment locations: across a county line and across Colorado
We assessed the performance of ambient ozone (O3) and carbon dioxide
(CO2) sensor field calibration techniques when they were generated using
data from one location and then applied to data collected at a new location.
This was motivated by a previous study (Casey et al., 2018), which highlighted
the importance of determining the extent to which field calibration
regression models could be aided by relationships among atmospheric trace
gases at a given training location, which may not hold if a model is applied
to data collected in a new location. We also explored the sensitivity of
these methods in response to the timing of field calibrations relative to
deployment periods. Employing data from a number of field deployments in
Colorado and New Mexico that spanned several years, we tested and compared
the performance of field-calibrated sensors using both linear models (LMs)
and artificial neural networks (ANNs) for regression. Sampling sites covered
urban and ruralāperi-urban areas and environments influenced by oil and gas production.
We found that the best-performing model inputs and model type depended on
circumstances associated with individual case studies, such as differing
characteristics of local dominant emissions sources, relative timing of model
training and application, and the extent of extrapolation outside of
parameter space encompassed by model training. In agreement with findings
from our previous study that was focused on data from a single location
(Casey et al., 2018), ANNs remained more effective than LMs
for a number of these case studies but there were some exceptions. For
CO2 models, exceptions included case studies in which training
data collection took place more than several months subsequent to the test
data period. For O3 models, exceptions included case studies in
which the characteristics of dominant local emissions sources (oil and gas
vs.Ā urban) were significantly different at model training and testing
locations. Among models that were tailored to case studies on an individual
basis, O3 ANNs performed better than O3 LMs in six out of
seven
case studies, while CO2 ANNs performed better than CO2
LMs in three out of five case studies. The performance of O3 models tended
to be more sensitive to deployment location than to extrapolation in time,
while the performance of CO2 models tended to be more sensitive to
extrapolation in time than to deployment location. The performance of
O3 ANN models benefited from the inclusion of several secondary
metal-oxide-type sensors as inputs in five of seven case studies.</p
Seasonal and Spatial Variation of the Bacterial Mutagenicity of Fine Organic Aerosol in Southern California
The bacterial mutagenicity of a set of 1993 urban particulate air pollution samples is examined using the Salmonella typhimurium TM677 forward mutation assay. Ambient fine particulate samples were collected for 24 hr every sixth day throughout 1993 at four urban sites, including Long Beach, central Los Angeles, Azusa, and Rubidoux, California, and at an upwind background site on San Nicolas Island. Long Beach and central Los Angeles are congested urban areas where air quality is dominated by fresh emissions from air pollution sources; Azusa and
Rubidoux are located farther downwind and receive transported air pollutants plus increased quantities of the products of atmospheric chemical reactions. Fine aerosol samples from Long Beach and Los Angeles show a pronounced seasonal variation in bacterial mutagenicity per cubic
meter of ambient air, with maximum in the winter and a minimum in the summer. The downwind smog receptor site at Rubidoux shows peak mutagenicity (with postmitochondrial supernatant but no peak without postmitochondrial supernatant) during the September-October periods when direct transport from upwind sources can be expected. At most sites the mutagenicity per microgram of organic carbon from the aerosol is not obviously higher during the
summer photochemical smog period than during the colder months. Significant spatial variation in bacterial mutagenicity is observed: mutagenicity per cubic meter of ambient air, on average, is more than an order of magnitude lower at San Nicolas Island than within the urban area. The
highest mutagenicity values per microgram of organics supplied to the assay are found at the most congested urban sites at central Los Angeles and Long Beach. The highest annual average values of mutagenicity per cubic meter of air sampled occur at central Los Angeles. These findings
stress the importance of proximity to sources of direct emissions of bacterial mutagens and imply that if important mutagen-forming atmospheric reactions occur, they likely occur in the winter and spring seasons as well as the photochemically more active summer and early fall periods
The moral muteness of managers: an Anglo-American phenomenon? German and British managers and their moral reasoning about environmental sustainability in business
Several studies in the Anglo-American context have indicated that managers present themselves as morally neutral employees who act only in the best interest of the company by employing objective skills. The reluctance of managers to use moral arguments in business is further accentuated in the now common argument presented as a neutral fact that the company must always prioritise shareholder value. These and other commercial aims are seen as an objective reality in business, whilst questions about sustainability, environmental problems or fair trade are seen as emotional or moral ones; a phenomenon described as āmoral mutenessā. This research explores whether this āmoral mutenessā is an Anglo-American phenomenon and/or whether managers in other countries - in this case Germany - might express themselves in a different way. The focus is on moral arguments around environmental sustainability and the implications of this study for cross-cultural management. This article is based on a qualitative, comparative cross-cultural study of British and German managers in the Food Retail and Energy Sectors. In line with the studies mentioned above, British managers placed a strong emphasis on their moral neutrality. In contrast, German managers tended to use moral arguments when discussing corporate greening, often giving such arguments more weight than financial arguments. Overall, the study suggests that the āmoral mutenessā of managers is a British phenomenon and quite distinct from the German approach. The article ends in a short exploration of how this understanding can help managers better manage people, organisations and change across cultures
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