810 research outputs found
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Donovanâs conjecture, blocks with abelian defect groups and discrete valuation rings
We give a reduction to quasisimple groups for Donovanâs conjecture for blocks with abelian defect groups defined with respect to a suitable discrete valuation ring O. Consequences are that Donovanâs conjecture holds for O-blocks with abelian defect groups for the prime two, and that, using recent work of Farrell and Kessar, for arbitrary primes Donovanâs conjecture for O-blocks with abelian defect groups reduces to bounding the Cartan invariants of blocks of quasisimple groups in terms of the defect. A result of independent interest is that in general (i.e. for arbitrary defect groups) Donovanâs conjecture for O-blocks is a consequence of conjectures predicting bounds on the O-Frobenius number and on the Cartan invariants, as was proved by Kessar for blocks defined over an algebraically closed field
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Arbitrarily large Morita Frobenius numbers
We construct blocks of finite groups with arbitrarily large Morita Frobenius numbers, an invariant which determines the size of the minimal field of definition of the associated basic algebra. This answers a question of Benson and Kessar. This also improves upon a result of the second author where arbitrarily large -Morita Frobenius numbers are constructed
Latent Inhibition Reduces Nocebo Nausea, Even Without Deception
Background: Nocebo nausea is a debilitating and prevalent side effect that can develop after conditioning occurs between cues present in the treatment context and the experience of nausea. Interventions that retard conditioning may therefore be able to reduce nocebo nausea. Purpose: To test whether âlatent inhibitionâ, where pre-exposing cues in the absence of an outcome retards subsequent learning about those cues, could reduce nocebo nausea in healthy adults. Methods: We examined this possibility using a Galvanic Vestibular Stimulation (GVS) model of nausea in healthy participants, with pre-exposure to the treatment cues achieved using a placebo version of GVS. Results: In Experiment 1 we found clear evidence of conditioned nocebo nausea that was eradicated by latent inhibition following pre-exposure to placebo stimulation. Experiment 2 tested whether deception, which may be unethical in clinical settings, was necessary to produce latent inhibition by including an open pre-exposure group informed they were pre-exposed to placebo stimulation. Experiment 2 replicated the latent inhibition effect on nocebo nausea following deceptive pre-exposure from Experiment 1 and found that open pre-exposure was just as effective for reducing nocebo nausea. In both experiments, there was an interesting discrepancy found in expectancy ratings whereby expectations appeared to drive the development of conditioned nocebo nausea, but were not responsible for its retardation through latent inhibition. Conclusions: These findings have significant clinical implications. Applying open pre-exposure in clinical settings may effectively and ethically reduce the development of nocebo effects for nausea and other conditions via latent inhibition
The role of contactin-associated protein-like 2 in neurodevelopmental disease and human cerebral cortex evolution
The contactin-associated protein-like 2 (CNTNAP2) gene is associated with multiple neurodevelopmental disorders, including autism spectrum disorder (ASD), intellectual disability (ID), and specific language impairment (SLI). Experimental work has shown that CNTNAP2 is important for neuronal development and synapse formation. There is also accumulating evidence for the differential use of CNTNAP2 in the human cerebral cortex compared with other primates. Here, we review the current literature on CNTNAP2, including what is known about its expression, disease associations, and molecular/cellular functions. We also review the evidence for its role in human brain evolution, such as the presence of eight human accelerated regions (HARs) within the introns of the gene. While progress has been made in understanding the function(s) of CNTNAP2, more work is needed to clarify the precise mechanisms through which CNTNAP2 acts. Such information will be crucial for developing effective treatments for CNTNAP2 patients. It may also shed light on the longstanding question of what makes us human
Chemical Protection Against Ionizing Radiation
The scientific literature on radiation-protective drugs is reviewed. Emphasis is placed on the mechanisms Involved in determining the sensitivity of biological material to ionizing radiation and mechanisms of chemical radioprotection. In Section 1, the types of radiation are described and the effects of ionizing radiation on biological systems are reviewed. The effects of ionizing radiation are briefly contrasted with the effects of non-Ionizing radiation. Section I reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Included in the list of these factors are water, oxygen, thiols, vitamins and antioxidants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) In determining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described In Section 111. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. Appendices are devoted to lists of currently-funded research projects Involving chemical radiation protection and a brief compendium of compounds which have been tested for radioprotective activity.https://scholarlycommons.pacific.edu/phs-facbooks/1016/thumbnail.jp
The UARS microwave limb sounder version 5 data set: Theory, characterization, and validation
Nitric acid (HNO3) is a major player in processes controlling the springtime depletion of polar ozone. It is the main constituent of the Polar Stratospheric Clouds (PSCs) and a primary reservoir for reactive nitrogen. Potential variations in the stratospheric circulation and temperature may alter the extent and duration of PSCs activity, influencing the future ozone levels significantly. Monitoring HNO3 and its long-term variability, especially in polar region, is then crucial for better understanding issues related to ozone decline and expected recovery. In this study we present an intercomparison between ground based HNO3 measurements, carried out by means of the Ground-Based Millimeter-wave Spectrometer (GBMS), and two satellite data sets produced by the two NASA/JPL Microwave Limb Sounder (MLS) experiments. In particular, we compare UARS MLS measurements (1991-1999) with those carried out by the GBMS at South Pole, Antarctica (90°S), Fall of 1993 and 1995. A similar
intercomparison is made between Aura MLS HNO3 observations (2004 - to date) and GBMS measurements obtained during the period February 2004 - March 2007, at the mid-latitudes/high altitudes station of Testa Grigia (45.9° N, 7.7° E, elev. 3500 m), and during polar winters 2008/09 and 2009/2010 at Thule Air Base (76.5°N 68.8°W), Greenland. We assess systematic differences between GBMS and both UARS and Aura HNO3 data sets at seven potential temperature levels (Ξ) spanning the range 465 â 960 K. The UARS data set advected to the South Pole shows a low bias, within 20% for all Ξ levels but the 960 K, with respect to GBMS measurements. A very good agreement, within 5%, is obtained between Aura and GBMS observations at Testa Grigia, while larger differences, possibly due to latitude dependent effects, are observed over Thule. These differences are under further investigations but a preliminary comparison over Thule among MLS v3, GBMS, and ACE-FTS measurements suggests that GBMS measurements carried out during winter 2009 might not be reliable. These comparisons have been performed in the framework of the NASA JPL GOZCARDS project, which is aimed at developing a long-term, global data record of the relevant stratospheric constituents in the context of ozone decline. GBMS has been selected in GOZCARDS since its HNO3 dataset, although sampling different latitudes in different years, is the only one spanning a sufficiently long time interval for cross-calibrating HNO3 measurements by the UARS and Aura MLS experiments
Characterizing sampling and quality screening biases in infrared and microwave limb sounding
This study investigates orbital sampling biases and evaluates the additional
impact caused by data quality screening for the Michelson Interferometer for
Passive Atmospheric Sounding (MIPAS) and the Aura Microwave Limb Sounder
(MLS). MIPAS acts as a proxy for typical infrared limb emission sounders,
while MLS acts as a proxy for microwave limb sounders. These biases were
calculated for temperature and several trace gases by interpolating model
fields to real sampling patterns and, additionally, screening those locations
as directed by their corresponding quality criteria. Both instruments have
dense uniform sampling patterns typical of limb emission sounders, producing
almost identical sampling biases. However, there is a substantial difference
between the number of locations discarded. MIPAS, as a mid-infrared
instrument, is very sensitive to clouds, and measurements affected by them
are thus rejected from the analysis. For example, in the tropics, the MIPAS
yield is strongly affected by clouds, while MLS is mostly unaffected.
The results show that upper-tropospheric sampling biases in zonally averaged
data, for both instruments, can be up to 10 to 30âŻ%, depending on the
species, and up to 3âŻK for temperature. For MIPAS, the sampling reduction
due to quality screening worsens the biases, leading to values as large as
30 to 100âŻ% for the trace gases and expanding the 3âŻK bias region for
temperature. This type of sampling bias is largely induced by the geophysical
origins of the screening (e.g. clouds). Further, analysis of long-term time
series reveals that these additional quality screening biases may affect the
ability to accurately detect upper-tropospheric long-term changes using such
data. In contrast, MLS data quality screening removes
sufficiently few points that no additional bias is introduced, although its
penetration is limited to the upper troposphere, while MIPAS may cover well
into the mid-troposphere in cloud-free scenarios. We emphasize that the
results of this study refer only to the representativeness of the respective
data, not to their intrinsic quality
Validation of Aura Microwave Limb Sounder O-3 and CO observations in the upper troposphere and lower stratosphere
International audienceGlobal satellite observations of ozone and carbon monoxide from the Microwave Limb Sounder (MLS) on the EOS Aura spacecraft are discussed with emphasis on those observations in the 215â100 hPa region (the upper troposphere and lower stratosphere). The precision, resolution and accuracy of the data produced by the MLS âversion 2.2â processing algorithms are discussed and quantified. O3 accuracy is estimated at ~40 ppbv +5% (~20 ppbv +20% at 215 hPa) while the CO accuracy is estimated at ~30 ppbv +30% for pressures of 147 hPa and less. Comparisons with expectations and other observations show good agreements for the O3 product, generally consistent with the systematic errors quoted above. In the case of CO, a persistent factor of ~2 high bias is seen at 215 hPa. However, the morphology is shown to be realistic, consistent with raw MLS radiance data, and useful for scientific study. The MLS CO data at higher altitudes are shown to be consistent with other observations
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Why are material efficiency solutions a limited part of the climate policy agenda? An application of the Multiple Streams Framework to UK policy on CO2 emissions from cars.
The Multiple Streams Framework is applied to investigate why material efficiency solutions are currently a limited part of the climate policy agenda. The case study under investigation is the UK agenda to reduce greenhouse gas emission from cars. Evidence from 14 semi-structured interviews, document analysis and academic studies is used to develop and substantiate the arguments made. In the UK, inefficient material use is only perceived as a problem insofar as it increases in-use vehicle emissions, which disadvantages some material efficiency solutions. The appeal of material efficiency solutions is further limited by a lack of real-world and modelling evidence, creating uncertainty around the anticipated costs and impacts of any policy intervention. Recent political developments are unlikely to make the UK government more receptive to the problem of greenhouse gases arising from inefficient material use in the future. This is further compounded by policy lock-in. Although a small community of policy entrepreneurs are promoting material efficiency solutions, they have disparate priorities, which impacts their effectiveness. The insights from this paper can inform future research and policy entrepreneurship to increase the likelihood of material efficiency solutions becoming a larger part of the climate policy agenda. The problem of climate change is too significant for any potential solutions to remain underexplored by policymakers in the UK and the rest of the world.Dr. Cooper-Searle is supported by a UK Engineering and Physical Sciences Research Council (EPSRC) PhD studentship EP/L504920/1, Dr. Livesey was supported by EPSRC grant EP/K039598/1 and Professor Allwood was supported by EPSRC grant EP/N02351X/1
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