Demographic Studies on Hawaii's Endangered Tree Snails: Partulina proxima

Populations of the tree snail Partulina proxima, endemic to higher elevations of Molokai, Hawaiian Islands, were studied for 3 years. Analyses of the data derived from 17bimonthly mark-recapture events determined that each tree harbors a small, mostly nonmigratory population of 8-26 snails of which 2-4 are adults; the snails average 4.2 mm long at birth and 21.3 mm long when growth stops; growth is slow, with maturity reached in 5-7 years; annual fecundity averages 6.2 offspring per adult; and mortality is about 98% over the first 4 years of life. Given the high rate of juvenile mortality, adult snails must reproduce for at least 12 years to replace themselves. From this we calculate a minimum maximal life-span of 18-19 years. We conclude that the current high rate of unexplained juvenile mortality, combined with lat e age at first reproduction and low fecundity, place this species at very high risk to any sort of perturbation, particularly any selective predation on adults

Demographic studies of homosporous fern populations in South Siberia

This paper presents the results of demographic studies in populations of six forest fer

Taking individual heterogeneity in mortality risks into account in demographic studies of wild animal populations: development and use of statistical models.

The Cormarck-Jolly-Seber model incorporating frailty implemented in WinBUGS, using the 9000 kittiwake’s dataset monitorized during 22 years, showed that the convergence is very low over computational view. We developed different kind of multistate model, considering independence/dependence between random effect of breeding and survival probability. The last part of the work was dedicated to model selection with Bayesian framework

All liaisons are dangerous when all your friends are known to us

Online Social Networks (OSNs) are used by millions of users worldwide. Academically speaking, there is little doubt about the usefulness of demographic studies conducted on OSNs and, hence, methods to label unknown users from small labeled samples are very useful. However, from the general public point of view, this can be a serious privacy concern. Thus, both topics are tackled in this paper: First, a new algorithm to perform user profiling in social networks is described, and its performance is reported and discussed. Secondly, the experiments --conducted on information usually considered sensitive-- reveal that by just publicizing one's contacts privacy is at risk and, thus, measures to minimize privacy leaks due to social graph data mining are outlined.Comment: 10 pages, 5 table

Rising marital disruption in Italy and its correlates

Most of our knowledge on divorce pertains to the USA and northern Europe, while demographic studies from southern Europe are relatively scarce. Our study looks at this knowledge gap through an analysis of the correlates of marital instability in Italy. We use the 2003 Italian Gender and Generation Survey, which reveals recent trends in marital disruption, including those among relatively young cohorts, and we employ event history techniques. Our results show that besides the expected correlation between marital disruption and the women’s birth cohort and socio-economic status, other factors more closely linked to specific aspects of Italian society can also be identified.correlates to marital disruption, event history analysis, Italy

Caltech Core-Collapse Project (CCCP) Observations of Type II Supernovae: Evidence for Three Distinct Photometric Subtypes

We present R-Band light curves of Type II supernovae (SNe) from the Caltech Core Collapse Project (CCCP). With the exception of interacting (Type IIn) SNe and rare events with long rise times, we find that most light curve shapes belong to one of three distinct classes: plateau, slowly declining and rapidly declining events. The last class is composed solely of Type IIb SNe which present similar light curve shapes to those of SNe Ib, suggesting, perhaps, similar progenitor channels. We do not find any intermediate light curves, implying that these subclasses are unlikely to reflect variance of continuous parameters, but rather might result from physically distinct progenitor systems, strengthening the suggestion of a binary origin for at least some stripped SNe. We find a large plateau luminosity range for SNe IIP, while the plateau lengths seem rather uniform at approximately 100 days. As analysis of additional CCCP data goes on and larger samples are collected, demographic studies of core collapse SNe will likely continue to provide new constraints on progenitor scenarios.Comment: Submitted to ApJ