231 research outputs found
Uncertainties on Central Exclusive Scalar Luminosities from the unintegrated gluon distributions
In a previous report we used the Linked Dipole Chain model unintegrated gluon
densities to investigate the uncertainties in the predictions for central
exclusive production of scalars at hadron colliders. Here we expand this
investigation by also looking at other parameterizations of the unintegrated
gluon density, and look in more detail on the behavior of these at small k_T.
We confirm our conclusions that the luminosity function for central exclusive
production is very sensitive to this behavior. However, we also conclude that
the available densities based on the CCFM and LDC evolutions are not
constrained enough to give reliable predictions even for inclusive Higgs
production at the LHC
Central Exclusive Scalar Luminosities from the Linked Dipole Chain Model gluon densities
We investigate the implication of uncertainties in the unintegrated gluon
distribution for the predictions for central exclusive production of scalars at
hadron colliders. We use parameterizations of the kT-unintegrated gluon density
obtained from the Linked Dipole Chain model, applying different options for the
treatment of non-leading terms. We find that the luminosity function for
central exclusive production is very sensitive to details of the transverse
momentum distribution of the gluon which, contrary to the kT-integrated
distribution, is not very well constrained experimentally
Protecting ocean carbon through biodiversity and climate governance
Global policy goals for halting biodiversity loss and climate change depend on each other to be successful. Marine biodiversity and climate change are intertwined through foodwebs that cycle and transport carbon and contribute to carbon sequestration. Yet, biodiversity conservation and fisheries management seldom explicitly include ocean carbon transport and sequestration. In order to effectively manage and govern human activities that affect carbon cycling and sequestration, international biodiversity and climate agreements need to address both biodiversity and climate issues. International agreements that address issues for climate and biodiversity are best poised to facilitate the protection of ocean carbon with existing policies. The degree to which the main international biodiversity and climate agreements make reference to multiple issues has however not been documented. Here, we used a text mining analysis of over 2,700 binding and non-binding policy documents from ten global ocean-related agreements to identify keywords related to biodiversity, climate, and ocean carbon. While climate references were mostly siloed within climate agreements, biodiversity references were included in most agreements. Further, we found that six percent of policy documents (n=166) included ocean carbon keywords. In light of our results, we highlight opportunities to strengthen the protection of ocean carbon in upcoming negotiations of international agreements, and via area-based management, environmental impact assessment and strategic environmental assessment
The chances of detecting life on Mars
AbstractMissions to Mars progressively reveal the past and present habitability of the red planet. The current priority for Mars science is the recognition of definitive biosignatures related to past or present life. Success of life detection missions requires choices of the best mission design, location on Mars and particular sample to be analyzed. It is essential therefore to incorporate as much information as possible into the mission planning stages to maximize the precious opportunities provided by robotic operation on Mars. Bayesian statistics allow us to accommodate the many unknowns associated with a mission that has yet to take place. We have used Bayesian statistics to reveal that although in situ missions are less complex the overall probabilities of a successful mission to detect biosignatures on Mars are higher for sample return. If a mission has been designed with safe landing and operation as a priority, recognizing and avoiding those samples that do not contain the target biosignature is the most important characteristic, while for a mission where the best possible samples have been targeted the probability that the sample contains the target biosignature and that it can be correctly detected is the most dominant issue. Usefully, Bayesian statistics can be used to evaluate the chances of detecting past or present life for missions to different landing sites on Mars. A comparative assessment of Eberswelde Crater and Gale Crater indicates a higher probability of success for the latter and the probabilities of success are consistently higher for the sample return mission variant. Bayesian statistics, therefore, can inform future Mars mission planning steps to help maximize the possibility of success
Cardiac expression of the microsomal triglyceride transport protein protects the heart function during ischemia
Aims: The microsomal triglyceride transport protein (MTTP) is critical for assembly and secretion of apolipoprotein B (apoB)-containing lipoproteins and is most abundant in the liver and intestine. Surprisingly, MTTP is also expressed in the heart. Here we tested the functional relevance of cardiac MTTP expression. Materials and methods: We combined clinical studies, advanced expression analysis of human heart biopsies and analyses in genetically modified mice lacking cardiac expression of the MTTP-A isoform of MTTP. Results: Our results indicate that lower cardiac MTTP expression in humans is associated with structural and perfusion abnormalities in patients with ischemic heart disease. MTTP-A deficiency in mice heart does not affect total MTTP expression, activity or lipid concentration in the heart. Despite this, MTTP-A deficient mice displayed impaired cardiac function after a myocardial infarction. Expression analysis of MTTP indicates that MTTP expression is linked to cardiac function and responses in the heart. Conclusions: Our results indicate that MTTP may play an important role for the heart function in conjunction to ischemic events
Deficiency of the lipid synthesis enzyme, DGAT1, extends longevity in mice
Calorie restriction results in leanness, which is linked to metabolic conditions that favor longevity. We show here that deficiency of the triglyceride synthesis enzyme acyl CoA:diacylglycerol acyltransferase 1 (DGAT1), which promotes leanness, also extends longevity without limiting food intake. Female DGAT1-deficient mice were protected from age-related increases in body fat, tissue triglycerides, and inflammation in white adipose tissue. This protection was accompanied by increased mean and maximal life spans of ~25% and ~10%, respectively. Middle-aged Dgat1−/− mice exhibited several features associated with longevity, including decreased levels of circulating insulin growth factor 1 (IGF1) and reduced fecundity. Thus, deletion of DGAT1 in mice provides a model of leanness and extended lifespan that is independent of calorie restriction
The Role of NMDA Receptor Antagonists in Nicotine Tolerance, Sensitization, and Physical Dependence: A Preclinical Review
Nicotine, the primary psychoactive component of tobacco products, produces diverse neurophysiological, motivational, and behavioral effects through several brain regions and neurochemical pathways. Various neurotransmitter systems have been explored to understand the mechanisms behind nicotine tolerance, dependence, and withdrawal. Recent evidence suggests that glutamate neurotransmission has an important role in this phenomenon. The aim of the present review is to discuss preclinical findings concerning the role of N-methyl-D-aspartate (NMDA) receptor neurotransmission in mediating the behavioral effects of nicotine, tolerance, sensitization, dependence, and withdrawal. Based on preclinical findings, it is hypothesized that NMDA receptors mediate the common adaptive processes that are involved in the development, maintenance, and expression of nicotine addiction. Modulation of glutamatergic neurotransmission with NMDA receptor antagonists may prove to be useful in alleviating the symptoms of nicotine abstinence and facilitate tobacco-smoking cessation
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