24,823 research outputs found
Gestational and lactational exposure of rats to xenoestrogens results in reduced testicular size and sperm production
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Use of any materials published in EHP should be acknowledged (for example, "Reproduced with permission from Environmental Health Perspectives") and a reference provided for the article from which the material was reproduced.This study assessed whether exposure of male rats to two estrogenic, environmental chemicals, 4-octylphenol (OP) and butyl benzyl phthalate (BBP) during gestation or during the first 21 days of postnatal life, affected testicular size or spermatogenesis in adulthood (90-95 days of age). Chemicals were administered via the drinking water or concentrations of 10-1000 micrograms/l (OP) or 1000 micrograms/l (BBP), diethylstilbestrol (DES; 100 micrograms/l) and an octylphenol polyethoxylate (OPP; 1000 micrograms/l), which is a weak estrogen or nonestrogenic in vitro, were administered as presumptive positive and negative controls, respectively. Controls received the vehicle (ethanol) in tap water. In study 1, rats were treated from days 1-22 after births in studies 2 and 3, the mothers were treated for approximately 8-9 weeks, spanning a 2-week period before mating throughout gestation and 22 days after giving birth. With the exception of DES, treatment generally had no major adverse effect or body weight: in most instances, treated animals were heavier than controls at day 22 and at days 90-95. Exposure to OP, OPP, or BBP at a concentration of 1000 micrograms/1 resulted in a small (5-13%) but significant (p < 0.01 or p < 0.0001) reduction in mean testicular size in studies 2 and 3, an effect that was still evident when testicular weight was expressed relative to body, weight or kidney weight. The effect of OPP is attributed to its metabolism in vivo to OP. DES exposure caused similar reductions in testicular size but also caused reductions in body weight, kidney weight, and litter size. Ventral prostate weight was reduced significantly in DES-treated rats and to minor extent in OP-treated rats. Comparable but more minor effects of treatment with DES or OP on testicular size were observed in study 1. None of the treatments had any adverse effect on testicular morphology or on the cross-sectional area of the lumen or seminiferous epithelium at stages VII-VIII of the spermatogenic cycle, but DES, OP, and BBP caused reductions of 10-21% (p < 0.05 to p < 0.001) in daily sperm production. Humans are exposed to phthalates, such as BBP, and to alkylphenol polyethoxylates, such as OP, but to what extent is unknown. More detailed studies are warranted to assess the possible risk to the development of the human testis from exposure to these and other environmental estrogens
Understanding Perceptions of Problematic Facebook Use: When People Experience Negative Life Impact and a Lack of Control
While many people use social network sites to connect with friends and
family, some feel that their use is problematic, seriously affecting their
sleep, work, or life. Pairing a survey of 20,000 Facebook users measuring
perceptions of problematic use with behavioral and demographic data, we
examined Facebook activities associated with problematic use as well as the
kinds of people most likely to experience it. People who feel their use is
problematic are more likely to be younger, male, and going through a major life
event such as a breakup. They spend more time on the platform, particularly at
night, and spend proportionally more time looking at profiles and less time
browsing their News Feeds. They also message their friends more frequently.
While they are more likely to respond to notifications, they are also more
likely to deactivate their accounts, perhaps in an effort to better manage
their time. Further, they are more likely to have seen content about social
media or phone addiction. Notably, people reporting problematic use rate the
site as more valuable to them, highlighting the complex relationship between
technology use and well-being. A better understanding of problematic Facebook
use can inform the design of context-appropriate and supportive tools to help
people become more in control.Comment: CHI 201
Improving mental health outcomes: achieving equity through quality improvement
Objective. To investigate equity of patient outcomes in a psychological therapy service, following increased access achieved by a quality improvement (QI) initiative. Design. Retrospective service evaluation of health outcomes; data analysed by ANOVA, chi-squared and Statistical Process Control. Setting. A psychological therapy service in Westminster, London, UK. Participants. People living in the Borough of Westminster, London, attending the service (from either healthcare professional or self-referral) between February 2009 and May 2012. Intervention(s). Social marketing interventions were used to increase referrals, including the promotion of the service through local media and through existing social networks. Main Outcome Measure(s). (i) Severity of depression on entry using Patient Health Questionnaire-9 (PHQ9). (ii) Changes to severity of depression following treatment (ΔPHQ9). (iii) Changes in attainment of a meaningful improvement in condition assessed by a key performance indicator. Results. Patients from areas of high deprivation entered the service with more severe depression (M = 15.47, SD = 6.75), com-pared with patients from areas of low (M = 13.20, SD = 6.75) and medium (M = 14.44, SD = 6.64) deprivation. Patients in low
A Review of Recent Positron Annihilation NDE Applications
This review will treat two recent applications of positron annihilation to metallurgical studies and will involve the measurement of the Doppler effect associated with the gamma rays emitted during positron annihilation. The applications will be: studies of the interactions of dislocations with pre-precipitates in aged Al-4 weight percent Cu single crystals and studies of the effect of hydrogen charging into polycrystalline nickel
Adsorptive graphene doping: Effect of a polymer contaminant
© 2017 Author(s). Transfer-induced contamination of graphene and the limited stability of adsorptive dopants are two of the main issues faced in the practical realization of graphene-based electronics. Herein, we assess the stability of HNO3, MoO3, and AuCl3 dopants upon transferred graphene with different extents of polymer contamination. Sheet resistivity measurements prove that polymer residues induce a significantly degenerative effect in terms of doping stability for HNO3 and MoO3 and a highly stabilizing effect for AuCl3. Further characterization by Raman spectroscopy and atomic force microscopy (AFM) provides insight into the stability mechanism. Together, these findings demonstrate the relevance of contamination in the field of adsorptive doping for the realization of graphene-based functional devices
Ambipolar charge injection and transport in a single pentacene monolayer island
Electrons and holes are locally injected in a single pentacene monolayer
island. The two-dimensional distribution and concentration of the injected
carriers are measured by electrical force microscopy. In crystalline monolayer
islands, both carriers are delocalized over the whole island. On disordered
monolayer, carriers stay localized at their injection point. These results
provide insight into the electronic properties, at the nanometer scale, of
organic monolayers governing performances of organic transistors and molecular
devices.Comment: To be published in Nano Letter
A combinatorial approach to knot recognition
This is a report on our ongoing research on a combinatorial approach to knot
recognition, using coloring of knots by certain algebraic objects called
quandles. The aim of the paper is to summarize the mathematical theory of knot
coloring in a compact, accessible manner, and to show how to use it for
computational purposes. In particular, we address how to determine colorability
of a knot, and propose to use SAT solving to search for colorings. The
computational complexity of the problem, both in theory and in our
implementation, is discussed. In the last part, we explain how coloring can be
utilized in knot recognition
Charged Lepton Electric Dipole Moments from TeV Scale Right-handed Neutrinos
We study the connection between charged lepton electric dipole moments,
, and seesaw neutrino mass generation in a simple two Higgs
doublet extension of the Standard Model plus three right-handed neutrinos (RHN)
, . For RHN with hierarchical masses and at least one with mass
in the 10 TeV range we obtain the upper bounds of
e-cm and e-cm. Our scenario favors the normal
mass hierarchy for the light neutrinos. We also calculated the cross section
for e^-e^- \ra W^- W^- in a high luminosity collider with constraints from
neutrinoless double beta decay of nuclei included. Among the rare muon decay
experiments we find that \mu\ra e\gamma is most sensitive and the upper limit
is .Comment: references added, typos correcte
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