7,619 research outputs found
Comparison of Solar and Other Influences on Long-term Climate
Examples are shown of climate variability, and unforced climate fluctuations are discussed, as evidenced in both model simulations and observations. Then the author compares different global climate forcings, a comparison which by itself has significant implications. Finally, the author discusses a new climate simulation for the 1980s and 1990s which incorporates the principal known global climate forcings. The results indicate a likelihood of rapid global warming in the early 1990s
Regional climate change and national responsibilities
Global warming over the past several decades is now large enough that regional climate change is emerging above the noise of natural variability, especially in the summer at middle latitudes and year-round at low latitudes. Despite the small magnitude of warming relative to weather fluctuations, effects of the warming already have notable social and economic impacts. Global warming of 2 °C relative to preindustrial would shift the 'bell curve' defining temperature anomalies a factor of three larger than observed changes since the middle of the 20th century, with highly deleterious consequences. There is striking incongruity between the global distribution of nations principally responsible for fossil fuel CO2 emissions, known to be the main cause of climate change, and the regions suffering the greatest consequences from the warming, a fact with substantial implications for global energy and climate policies
Prevented Mortality and Greenhouse Gas Emissions From Historical and Projected Nuclear Power
In the aftermath of the March 2011 accident at Japan's Fukushima Daiichi nuclear power plant, the future contribution of nuclear power to the global energy supply has become somewhat uncertain. Because nuclear power is an abundant, low-carbon source of base-load power, it could make a large contribution to mitigation of global climate change and air pollution. Using historical production data, we calculate that global nuclear power has prevented an average of 1.84 million air pollution-related deaths and 64 gigatonnes of CO2-equivalent (GtCO2-eq) greenhouse gas (GHG) emissions that would have resulted from fossil fuel burning. On the basis of global projection data that take into account the effects of the Fukushima accident, we find that nuclear power could additionally prevent an average of 420 0007.04 million deaths and 80240 GtCO2-eq emissions due to fossil fuels by midcentury, depending on which fuel it replaces. By contrast, we assess that large-scale expansion of unconstrained natural gas use would not mitigate the climate problem and would cause far more deaths than expansion of nuclear power
Support for faster and more adaptive Z chromosome evolution in two divergent lepidopteran lineages<sup>*</sup>
The rateof divergence for Z or X chromosomes is usually observed to be greater than autosomes, but the proposed evolutionary causes for this pattern vary, as do empirical results from diverse taxa. Even among moths and butterflies (Lepidoptera), which generally share a single‐origin Z chromosome, the handful of available studies give mixed support for faster or more adaptive evolution of the Z chromosome, depending on the species assayed. Here, we examine the molecular evolution of Z chromosomes in two additional lepidopteran species: the Carolina sphinx moth and the monarch butterfly, the latter of which possesses a recent chromosomal fusion yielding a segment of newly Z‐linked DNA. We find evidence for both faster and more adaptive Z chromosome evolution in both species, although this effect is strongest in the neo‐Z portion of the monarch sex chromosome. The neo‐Z is less male‐biased than expected of a Z chromosome, and unbiased and female‐biased genes drive the signal for adaptive evolution here. Together these results suggest that male‐biased gene accumulation and haploid selection have opposing effects on long‐term rates of adaptation and may help explain the discrepancies in previous findings as well as the repeated evolution of neo‐sex chromosomes in Lepidoptera
A dynamical theory of homogeneous nucleation for colloids and macromolecules
Homogeneous nucleation is formulated within the context of fluctuating
hydrodynamics. It is shown that for a colloidal or macromolecular system in the
strong damping limit the most likely path for nucleation can be determined by
gradient descent in density space governed by a nontrivial metric fixed by the
dynamics. The theory provides a justification and extension of more heuristic
equilibrium approaches based solely on the free energy. It is illustrated by
application to liquid-vapor nucleation where it is shown that, in contrast to
most free energy-based studies, the smallest clusters correspond to long
wavelength, small amplitude perturbations.Comment: final version; 4 pages, 2 figure
Impacts of seasonal climate communication strategies on farm management and livelihoods in Wote, Kenya
This study was undertaken in Wote division, Makueni district, Eastern province, Kenya, to test the effectiveness of different methods of communicating downscaled seasonal climate forecast information, and to assess its impact on management and productivity of smallholder farms. The communication methods tested include training workshops aimed at helping farmers understand downscaled probabilistic climate forecast information, agro-advisories that combined forecast information with advice on potential management options, and a combination of training and agro-advisory workshops. The study was conducted with about 120 farmers, 10 from each of 12 villages selected randomly from the villages that are within a 5 km radius from Kampi Ya Mawe research station for which long-term climate records are available, during the 2011-2012 short rain season. Three surveys, implemented during the pre-, mid- and end-season periods, captured changes in management, productivity, and attitudes, associated with the provision of climate information.
Relative to the control sample, farmers with access to enhanced climate information reduced their cropped area, invested in more intensive crop management, and achieved higher yields with attractive returns on investment relative to farmers in control villages. Farmers from treatment villages also demonstrated appreciation of the role of climate information in planning and managing farm activities, higher satisfaction with the season, and strong interest in receiving climate information on a regular basis. This interest was demonstrated by their willingness to pay a modest amount for the service if required. The evaluation was disaggregated by gender. Gender influenced adjustments to crop mix in response to climate information, with women preferring short-duration legumes. Gender did not appear to affect the subjective value put on climate information, or willingness to pay.
The study findings suggest that both of the workshop-based approaches to communicating climate information improved farers’ ability to manage risks. However the sample size was not sufficient to provide conclusive evidence of the impact on yields, investments or livelihoods. It is therefore suggested that similar assessments with a much larger sample in different agro-ecologies, and more comprehensive baseline data collection, be planned to make a more conclusive assessment of farmers’ ability to understand, utilize and benefit from
seasonal climate forecast information. Such a study should aim to develop and refine training 3
modules that can help farmers and their support agents better understand climate variability, probabilistic forecasts and their application, and appropriate communication systems aimed at providing timely access to required climate information
Farmer training workshops on understanding probabilistic seasonal forecasts: Wote, Kenya, 14-16 and 20-23 September 2011
This report presents the work done during farmer training workshops on probabilistic seasonal forecasting and forecast-based advisories, in Wote, Makueni County, Kenya. This activity took into consideration the fact that farmers in Mahueni County in semi-arid eastern Kenya mainly rely on rainfall for their agricultural production. The rainfall is, however, highly variable in amounts and distribution both seasonally and annually making farming in the region a risky business. The goal of the project was therefore, to train farmers in the identified areas of Makueni to better understand the climate of their location and explore how they can manage the effects of the variability in rainfall in order to improve their farm production. The area was selected due to previous as well as on-going studies implemented by ICRISAT, KALRO and other collaborators. The aim of the training was to empower farmers with knowledge on the use of forecast information and to enable them make better use of this knowledge in their farm planning for improved household food security. The trainings were conducted on the 14-16 and 20-23 September 2011, before the onset of the short rain (October-December) season. It was part of a study that covered twelve villages in Wote Division, Makueni County. Ten farmer participants were selected per village giving a total of 120 farmers. These workshops were sponsored by the Climate Change Agriculture and Food Security (CCAFS) project under the Theme “Adaptation through Managing Climate Risk,” and implemented in collaboration with International Crops Research Institute for the Semi-Arid-Tropics (ICRISAT), Kenya Agricultural and Livestock Research Organization (KALRO), Kenya Meteorological Services (KMS), the Ministry of Agriculture (MoA), and International Research Institute for Climate and Society (IRI)
S-duality in AdS/CFT magnetohydrodynamics
We study the nonlinear hydrodynamics of a 2+1 dimensional charged conformal
fluid subject to slowly varying external electric and magnetic fields.
Following recent work on deriving nonlinear hydrodynamics from gravity, we
demonstrate how long wavelength perturbations of the AdS dyonic black brane
solution of 4D supergravity are governed by equations equivalent to fluid
dynamics equations in the boundary theory. We investigate the implications of
-duality for our system, and derive restrictions imposed on the transport
coefficients of a generic fluid invariant under the S operation. We also expand
on our earlier work and determine a new set of previously undetermined
transport coefficients for the conformal fluid with an AdS gravity dual. Quite
surprisingly, we discover that half of the transport coefficients allowed by
symmetry vanish in the holographic fluid at linear order in the hydrodynamic
expansion.Comment: 25 page
The use of water bowls in the dairy barn
1. Dairy cows, watered by means of water bowls, drank approximately 18 percent more water and yielded 3.5 percent more milk and 10.7 percent more butterfat than cows that were watered twice per day at an outside tank.
2. Cows watered with water bowls drank an average of about 10 times in each 24 hours. Approximately two-thirds of the water was consumed in the daytime, that is between 5 a. m. and 5 p. m., and the other one-third at night.
3. Cows watered at the outside tank frequently drank but once per day. This occurred about 30 percent of the times the cows were offered water. This refusal to drink more than once per day was distributed among all of the cows, although certain cows showed a greater disposition to drink but once per day than did others. The inclination to drink but once per day was not consistently correlated with the quantity of milk yielded.
4. One unusual observation was that when the cows were watered with water bowls, they usually yielded not only more milk but milk containing a higher percentage of butterfat. A mathematical treatment of the data shows that the probability is only about 4 in 100 that a result as large and consistent could have come by chance alone.
5. The temperature of the water apparently did not influence the water consumption as greatly as did atmospheric temperature. The relative consumption of water increased as temperature rose
Pulmonary function in primary pulmonary hypertension
AbstractObjectivesThe study was done to ascertain the degree to which abnormalities in resting lung function correlate with the disease severity of patients with primary pulmonary hypertension (PPH).BackgroundPatients with PPH are often difficult to diagnose until several years after the onset of symptoms. Despite the seriousness of the disorder, the diagnosis of PPH is often delayed because it is unsuspected and requires invasive measurements. Although PPH often causes abnormalities in resting lung function, these abnormalities have not been shown to be statistically significant when correlated with other measures of PPH severity.MethodsResting lung mechanics and diffusing capacity for carbon monoxide DLcowere assessed in 79 patients whose findings conformed to the classical diagnostic criteria of PPH and who had no evidence of secondary causes of pulmonary hypertension. These findings were correlated with severity of disease as assessed by cardiac catheterization, New York Heart Association (NYHA) class, and cardiopulmonary exercise testing.ResultsWhen PPH patients were first evaluated at our referral clinic, the DLcoand lung volumes were decreased in approximately three-quarters and one-half, respectively. The decreases in DLco, and to a lesser extent lung volumes, correlated significantly with decreases in peak oxygen uptake (reflecting maximum cardiac output), peak oxygen pulse (reflecting maximum stroke volume), and anaerobic threshold (reflecting sustainable exercise capacity) and higher NYHA class.ConclusionsPatients with PPH commonly have abnormalities in lung mechanics and DLcolevels that correlate significantly with disease severity. These measurements can be useful in evaluating patients with unexplained dyspnea and fatigue
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