722 research outputs found
Suicide ideation of individuals in online social networks
Suicide explains the largest number of death tolls among Japanese adolescents
in their twenties and thirties. Suicide is also a major cause of death for
adolescents in many other countries. Although social isolation has been
implicated to influence the tendency to suicidal behavior, the impact of social
isolation on suicide in the context of explicit social networks of individuals
is scarcely explored. To address this question, we examined a large data set
obtained from a social networking service dominant in Japan. The social network
is composed of a set of friendship ties between pairs of users created by
mutual endorsement. We carried out the logistic regression to identify users'
characteristics, both related and unrelated to social networks, which
contribute to suicide ideation. We defined suicide ideation of a user as the
membership to at least one active user-defined community related to suicide. We
found that the number of communities to which a user belongs to, the
intransitivity (i.e., paucity of triangles including the user), and the
fraction of suicidal neighbors in the social network, contributed the most to
suicide ideation in this order. Other characteristics including the age and
gender contributed little to suicide ideation. We also found qualitatively the
same results for depressive symptoms.Comment: 4 figures, 9 table
Prevention of sexual transmission of Ebola in Liberia through a national semen testing and counselling programme for survivors: an analysis of Ebola virus RNA results and behavioural data
Background Ebola virus has been detected in semen of Ebola virus disease survivors after recovery. Liberia’s Men’s
Health Screening Program (MHSP) off ers Ebola virus disease survivors semen testing for Ebola virus. We present
preliminary results and behavioural outcomes from the fi rst national semen testing programme for Ebola virus.
Methods The MHSP operates out of three locations in Liberia: Redemption Hospital in Montserrado County, Phebe
Hospital in Bong County, and Tellewoyan Hospital in Lofa County. Men aged 15 years and older who had an Ebola
treatment unit discharge certifi cate are eligible for inclusion. Participants’ semen samples were tested for Ebola virus
RNA by real-time RT-PCR and participants received counselling on safe sexual practices. Participants graduated after
receiving two consecutive negative semen tests. Counsellors collected information on sociodemographics and sexual
behaviours using questionnaires administered at enrolment, follow up, and graduation visits. Because the programme
is ongoing, data analysis was restricted to data obtained from July 7, 2015, to May 6, 2016.
Findings As of May 6, 2016, 466 Ebola virus disease survivors had enrolled in the programme; real-time RT-PCR
results were available from 429 participants. 38 participants (9%) produced at least one semen specimen that tested
positive for Ebola virus RNA. Of these, 24 (63%) provided semen specimens that tested positive 12 months or longer
after Ebola virus disease recovery. The longest interval between discharge from an Ebola treatment unit and collection
of a positive semen sample was 565 days. Among participants who enrolled and provided specimens more than
90 days since their Ebola treatment unit discharge, men older than 40 years were more likely to have a semen sample
test positive than were men aged 40 years or younger (p=0·0004). 84 (74%) of 113 participants who reported not using
a condom at enrolment reported using condoms at their fi rst follow-up visit (p<0·0001). 176 (46%) of 385 participants
who reported being sexually active at enrolment reported abstinence at their follow-up visit (p<0·0001).
Interpretation Duration of detection of Ebola virus RNA by real-time RT-PCR varies by individual and might be
associated with age. By combining behavioural counselling and laboratory testing, the Men’s Health Screening
Program helps male Ebola virus disease survivors understand their individual risk and take appropriate measures to
protect their sexual partners
Bioindicators assessing water quality and environmental impacts of water treatment plant sludge.
This study had as objectives to assess water quality using macroinvertebrate communities in Gaviao artificial reservoir (Brazil), used to supply potable water to 2.5 million people, and to evaluate how these organisms responded to the discharge of water treatment sludge into a natural wetland. A total of 1,621 specimens across 23 taxa were identified. Mollusca were the dominant and most frequent group while Insecta presented the most richness. Based on feeding mode, there were more predator organisms than scrapers. The Biological Monitoring Working Party (BMWP') method showed to be more sensible to water quality variations than ASPT index, going from polluted to questionable water quality more frequently. The chemical parameters analysed showed no significant variations and were not a sensitive method for assessing water quality. No organisms could be found downstream of the sludge discharge point, indicating a high impact of sludge disposal on local biota
Wide-angle elastic scattering and color randomization
Baryon-baryon elastic scattering is considered in the independent scattering
(Landshoff) mechanism. It is suggested that for scattering at moderate
energies, direct and interchange quark channels contribute with equal color
coefficients because the quark color is randomized by soft gluon exchange
during the hadronization stage. With this assumption, it is shown that the
ratio of cross sections at CM angle
decreases from a high energy value of R_{\pbar p / pp} \approx 1/2.7, down to
R_{\pbar p / pp} \approx 1/28, compatible with experimental data at moderate
energies. This sizable fall in the ratio seems to be characteristic of the
Landshoff mechanism, in which changes at the quark level have a strong effect
precisely because the hadronic process occurs via multiple quark scatterings.
The effect of color randomization on the angular distribution of proton-proton
elastic scattering and the cross section ratio is also discussed.Comment: 18 pages, latex2e, 4 uuencoded figures, include
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