2,797 research outputs found
A Predictive Algorithm For Wetlands In Deep Time Paleoclimate Models
Methane is a powerful greenhouse gas produced in wetland environments via microbial action in anaerobic conditions. If the location and extent of wetlands are unknown, such as for the Earth many millions of years in the past, a model of wetland fraction is required in order to calculate methane emissions and thus help reduce uncertainty in the understanding of past warm greenhouse climates. Here we present an algorithm for predicting inundated wetland fraction for use in calculating wetland methane emission fluxes in deep time paleoclimate simulations. The algorithm determines, for each grid cell in a given paleoclimate simulation, the wetland fraction predicted by a nearest neighbours search of modern day data in a space described by a set of environmental, climate and vegetation variables. To explore this approach, we first test it for a modern day climate with variables obtained from observations and then for an Eocene climate with variables derived from a fully coupled global climate model (HadCM3BL-M2.2). Two independent dynamic vegetation models were used to provide two sets of equivalent vegetation variables which yielded two different wetland predictions. As a first test the method, using both vegetation models, satisfactorily reproduces modern data wetland fraction at a course grid resolution, similar to those used in paleoclimate simulations. We then applied the method to an early Eocene climate, testing its outputs against the locations of Eocene coal deposits. We predict global mean monthly wetland fraction area for the early Eocene of 8 to 10 Ă 106km2 with corresponding total annual methane flux of 656 to 909 Tg, depending on which of two different dynamic global vegetation models are used to model wetland fraction and methane emission rates. Both values are significantly higher than estimates for the modern-day of 4 Ă 106km2 and around 190Tg (Poulter et. al. 2017, Melton et. al., 2013
Effects of High Charge Densities in Multi-GEM Detectors
A comprehensive study, supported by systematic measurements and numerical
computations, of the intrinsic limits of multi-GEM detectors when exposed to
very high particle fluxes or operated at very large gains is presented. The
observed variations of the gain, of the ion back-flow, and of the pulse height
spectra are explained in terms of the effects of the spatial distribution of
positive ions and their movement throughout the amplification structure. The
intrinsic dynamic character of the processes involved imposes the use of a
non-standard simulation tool for the interpretation of the measurements.
Computations done with a Finite Element Analysis software reproduce the
observed behaviour of the detector. The impact of this detailed description of
the detector in extreme conditions is multiple: it clarifies some detector
behaviours already observed, it helps in defining intrinsic limits of the GEM
technology, and it suggests ways to extend them.Comment: 5 pages, 6 figures, 2015 IEEE Nuclear Science Symposiu
A splice intervention therapy for autosomal recessive juvenile Parkinsonâs disease arising from Parkin mutations
Parkin-type autosomal recessive juvenile-onset Parkinsonâs disease is caused by mutations in the PRKN gene and accounts for 50% of all autosomal recessive Parkinsonism cases. Parkin is a neuroprotective protein that has dual functions as an E3 ligase in the ubiquitinâproteasome system and as a transcriptional repressor of p53. While genomic deletions of PRKN exon 3 disrupt the mRNA reading frame and result in the loss of functional parkin protein, deletions of both exon 3 and 4 maintain the reading frame and are associated with a later onset, milder disease progression, indicating this particular isoform retains some function. Here, we describe in vitro evaluation of antisense oligomers that restore functional parkin expression in cells derived from a Parkinsonâs patient carrying a heterozygous PRKN exon 3 deletion, by inducing exon 4 skipping to correct the reading frame. We show that the induced PRKN transcript is translated into a shorter but semi-functional parkin isoform able to be recruited to depolarised mitochondria, and also transcriptionally represses p53 expression. These results support the potential use of antisense oligomers as a disease-modifying treatment for selected pathogenic PRKN mutations
Targeted molecular therapeutics for Parkinson's Disease: A role for antisense oligonucleotides?
Parkinson's disease (PD) is a prevalent neurodegenerative disorder characterized by marked heterogeneity in clinical symptoms and a complex genetic background..
Charge Transfer Properties Through Graphene for Applications in Gaseous Detectors
Graphene is a single layer of carbon atoms arranged in a honeycomb lattice
with remarkable mechanical and electrical properties. Regarded as the thinnest
and narrowest conductive mesh, it has drastically different transmission
behaviours when bombarded with electrons and ions in vacuum. This property, if
confirmed in gas, may be a definitive solution for the ion back-flow problem in
gaseous detectors. In order to ascertain this aspect, graphene layers of
dimensions of about 2x2cm, grown on a copper substrate, are transferred
onto a flat metal surface with holes, so that the graphene layer is freely
suspended. The graphene and the support are installed into a gaseous detector
equipped with a triple Gaseous Electron Multiplier (GEM), and the transparency
properties to electrons and ions are studied in gas as a function of the
electric fields. The techniques to produce the graphene samples are described,
and we report on preliminary tests of graphene-coated GEMs.Comment: 4pages, 3figures, 13th Pisa Meeting on Advanced Detector
Whatâs sex got to do with it? A family-based investigation of growing up heterosexual during the twentieth century
This paper explores findings from a cross-generational study of the making of heterosexual relationships in East Yorkshire, which has interviewed women and men within extended families. Using a feminist perspective, it examines the relationship between heterosexuality and adulthood, focussing on sexual attraction, courtship, first kisses, first love and first sex, as mediated within family relationships, and at different historical moments. In this way, the contemporary experiences of young people growing up are compared and contrasted with those of mid-lifers and older adults who formed heterosexual relationships within the context of the changing social and sexual mores of the 1960s/1970s, and the upheavals of World War Two
Design, Implementation and First Measurements with the Medipix Neutron Camera in CMS
The Medipix detector is the first device dedicated to measuring mixed-field
radiation in the CMS cavern and able to distinguish between different particle
types. Medipix2-MXR chips bump bonded to silicon sensors with various neutron
conversion layers developed by the IEAP CTU in Prague were successfully
installed for the 2008 LHC start-up in the CMS experimental and services
caverns to measure the flux of various particle types, in particular neutrons.
They have operated almost continuously during the 2010 run period, and the
results shown here are from the proton run between the beginning of July and
the end of October 2010. Clear signals are seen and different particle types
have been observed during regular LHC luminosity running, and an agreement in
the measured flux rate is found with the simulations. These initial results are
promising, and indicate that these devices have the potential for further and
future LHC and high energy physics applications as radiation monitoring devices
for mixed field environments, including neutron flux monitoring. Further
extensions are foreseen in the near future to increase the performance of the
detector and its coverage for monitoring in CMS.Comment: 15 pages, 16 figures, submitted to JINS
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