248 research outputs found
Modelling extreme rain accumulation with an application to the 2011 Lake Champlain flood
A simple strategy is proposed to model total accumulation in non-overlapping clusters
of extreme values from a stationary series of daily precipitation. Assuming that each cluster
contains at least one value above a high threshold, the cluster sum S is expressed as the ratio
S=M/P of the cluster maximum M and a random scaling factor P (0, 1]. The joint distribution
for the pair (M, P) is then specified by coupling marginal distributions for M and P with a copula.
Although the excess distribution of M is well approximated by a generalized Pareto distribution,
it is argued that, conditionally on P<1, a scaled beta distribution may already be sufficiently rich
to capture the behaviour of P . An appropriate copula for the pair (M, P) can also be selected by
standard rank-based techniques.This approach is used to analyse rainfall data from Burlington,
Vermont, and to estimate the return period of the spring 2011 precipitation accumulation which
was a key factor in that yearâs devastating flood in the RichelieuValley Basin in QuÂŽebec, Canada
Direct observation of multi-ionization and multi-fragmentation in a high-velocity cluster-atom collision
IPMWe report the direct observation of the multi-ionization of the hydrogen cluster in a single collision with a helium atom at 60 keV/u. Up to quadruple ionization of the cluster was observed and new multi-fragmentation channel were detected. Moreover, the results show two different fragmentation processes of doubly charged clusters: emission of an dimer, or emission of an trimer after rearrangement in the cluster prior to fragmentation
Clonal expansion and epigenetic reprogramming following deletion or amplification of mutant
IDH1 mutation is the earliest genetic alteration in low-grade gliomas (LGGs), but its role in tumor recurrence is unclear. Mutant IDH1 drives overproduction of the oncometabolite d-2-hydroxyglutarate (2HG) and a CpG island (CGI) hypermethylation phenotype (G-CIMP). To investigate the role of mutant IDH1 at recurrence, we performed a longitudinal analysis of 50 IDH1 mutant LGGs. We discovered six cases with copy number alterations (CNAs) at the IDH1 locus at recurrence. Deletion or amplification of IDH1 was followed by clonal expansion and recurrence at a higher grade. Successful cultures derived from IDH1 mutant, but not IDH1 wild type, gliomas systematically deleted IDH1 in vitro and in vivo, further suggestive of selection against the heterozygous mutant state as tumors progress. Tumors and cultures with IDH1 CNA had decreased 2HG, maintenance of G-CIMP, and DNA methylation reprogramming outside CGI. Thus, while IDH1 mutation initiates gliomagenesis, in some patients mutant IDH1 and 2HG are not required for later clonal expansions
Bottom-up Infrastructures: Aligning Politics and Technology in building a Wireless Community Network
Contemporary innovation in infrastructures is increasingly characterized by a close relationship between experts and lay people. This phenomenon has attracted the attention from a wide range of disciplines, including computer-supported cooperative work (CSCW), science and technology studies (S&TS), organization studies and participatory design (PD). Connecting to this broad area of research, the article presents a qualitative case study concerning the building and maintenance of a grassroots, bottom-up information infrastructure in Italy, defined as wireless community network (WCN). Methodologically, the research is based on qualitative interviews with participants to the WCN, ethnographic observations and document analysis. The aim of the article is to understand the alignment between the technical work implied in building this bottom-up infrastructure and the political and cultural frameworks that move people to participate to this project. Relying on the field of science & technology studies, and in particular on the notions of âinverse infrastructureâ and âresearch in the wildâ, we disclose the WCNâs peculiar innovation trajectory, localized outside conventional spaces of research and development. Overall, the presentation of the qualitative and ethnographic data allows to point out a more general reflection on bottom-up infrastructures and to enrich the academic debate concerning bottom-up infrastructuring work and other similar typologies of collaborative design projects in the domain of infrastructures
Aspirin and lung cancer in women
The association between aspirin use and lung cancer risk in women was examined in a caseâcontrol study nested in the New York University Women's Health Study, a large cohort in New York. Case subjects were all the 81 incident lung cancer cases who had provided information about aspirin use at enrollment and during the 1994â1996 follow up. Ten controls per case were randomly selected from among study participants who matched a case by age, menopausal status, and dates of enrollment and follow-up. Relative to no aspirin use, the odds ratio for lung cancer (all histological sub-types combined) among subjects who reported aspirin use three or more times per week for at least 6 months was 0.66 (95% confidence interval 0.34â1.28), after adjustment for smoking and education. A stronger inverse association was observed in analyses restricted to non-small cell lung cancer (adjusted odds ratio 0.39, 95% confidence interval 0.16â0.96). These results suggest that regular aspirin use might be inversely associated with risk of lung cancer in women, particularly the non-small cell sub-type
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