1,416 research outputs found
Three-dimensional view of ultrafast dynamics in photoexcited bacteriorhodopsin in the multiphoton regime and biological relevance
How does chemistry scale in complexity to unerringly direct biological functions? Nass Kovacs et al. have shown that bacteriorhodopsin undergoes structural changes tantalizingly similar to the expected pathway even under excessive excitation. Is the protein structure so highly evolved that it directs all deposited energy into the designed function
Les expériences vécues par les enfants de Duplessis institutionnalisés : les conséquences aprÚs plus de 50 ans
Dans cet article, les auteurs prĂ©sentent les rĂ©sultats qualitatifs recueillis Ă partir de questionnaires et dâentrevues semi-structurĂ©es destinĂ©s Ă documenter les expĂ©riences tant actuelles que passĂ©es des enfants de Duplessis institutionnalisĂ©s (EDI). Des exemples typiques et deux cas reprĂ©sentatifs sont prĂ©sentĂ©s. Les rĂ©sultats indiquent que les abus et la nĂ©gligence subis par les EDI pendant lâenfance ont compromis leur ajustement psychosocial Ă long terme. Ils rĂ©vĂšlent aussi que les EDI qui ont rapportĂ© au moins quatre forces pendant leur enfance Ă©taient plus susceptibles dâĂȘtre protĂ©gĂ©s Ă lâĂąge adulte contre les effets nĂ©gatifs de leur placement.In this article, the authors present qualitative results, derived from questionnaires and semi-structured interviews, to describe past and present experiences of the Duplessis children. Examples representative of their experience and a detailed description of two cases are provided. Results indicate that childhood abuse and negligence are related to poorer long-term psychological adjustment. The findings also demonstrate that reporting at least four strengths in childhood can have long-term protective effects.En este artĂculo, los autores presentan los resultados cualitativos recopilados a partir de cuestionarios y entrevistas semiestructuradas destinadas a documentar las experiencias, tanto recientes como pasadas, de los niños de Duplessis que fueron institucionalizados (EDI). Se presentan ejemplos tĂpicos y dos casos representativos. Los resultados indican que los abusos y la negligencia sufridos por los EDI durante la infancia han comprometido su ajuste psicosocial a largo plazo. TambiĂ©n revelan que los EDI que han reportado al menos cuatro fuerzas durante su infancia eran mĂĄs susceptibles de estar protegidos en la edad adulta contra los efectos negativos de su colocaciĂłn.Neste artigo, os autores apresentam os resultados qualitativos coletados a partir de questionĂĄrios e entrevistas semi-estruturadas destinados a documentar as experiĂȘncias tanto atuais quanto passadas das crianças de Duplessis institucionalizadas (CDI). SĂŁo apresentados exemplos tĂpicos e dois casos representativos. Os resultados indicam que os abusos e a negligĂȘncia sofridos pelas CDI durante a infĂąncia comprometeram seu ajuste psicossocial a longo prazo. Eles revelam tambĂ©m que as CDI que relataram, pelo menos, quatro aspectos positivos durante sua infĂąncia eram mais susceptĂveis de ser protegidas durante a idade adulta contra os efeitos negativos de sua internação
RĂ©percussions dâune enfance vĂ©cue en institution : le cas des Enfants de Duplessis
Les consĂ©quences nĂ©gatives dâun placement en institution sur les enfants ont Ă©tĂ© documentĂ©es, mais aucune Ă©tude nâa portĂ© sur les orphelins et les enfants placĂ©s une fois devenus adultes. Au QuĂ©bec, les Enfants de Duplessis offrent un tĂ©moignage poignant des rĂ©percussions Ă long terme dâune enfance vĂ©cue en institution. Les histoires recueillies auprĂšs de 40 hommes et 41 femmes ayant grandi en institution Ă lâĂ©poque de Duplessis font Ă©tat dâun nombre Ă©levĂ© dâabus et dâexpĂ©riences adverses, incluant les agressions physiques, psychologiques et sexuelles. Le milieu Ă©tait peu stimulant et offrait peu dâopportunitĂ©s de dĂ©velopper des relations dâattachement positives et significatives. Lorsquâils sont appariĂ©s et comparĂ©s Ă des adultes provenant de lâenquĂȘte SantĂ©-QuĂ©bec, les Enfants de Duplessis devenus adultes rapportent plus de problĂšmes de santĂ© liĂ©s au stress et une dĂ©tresse psychologique plus importante. Nos rĂ©sultats indiquent Ă©galement que les personnes ayant disposĂ© de peu de ressources et dâaptitudes personnelles dans lâenfance sont les plus affectĂ©es par les expĂ©riences adverses.Whereas the immediate consequences of institutionalized placements on children have been documented, no study has investigated adults who were raised in orphanages or institutions. In Quebec, les enfants de Duplessis offer a unique testimony of the long term consequences of an institutionalized childhood. Stories collected from 40 men and 41 women who grew up in institution in Duplessisâera indicate a high number of abuse and aversive experiences, including physical, psychological and sexual aggressions. In addition, the environment was poor in stimulation and opportunities to develop positive attachment relationships with adults. When matched and compared to adults from the SantĂ©-QuĂ©bec survey, les enfants de Duplessis report a higher number of health problems associated with stress and more psychological distress. Moreover, our results indicate that those who had fewer strengths and aptitudes in childhood are the most affected by unfavourable experiences.Se han documentado las consecuencias negativas del ingreso de los niños a una instituciĂłn, pero ningĂșn estudio trata acerca de los adultos que fueron internados cuando eran niños o quedaron huĂ©rfanos. En Quebec los niños de Duplessis son un testimonio desgarrador de las repercusiones a largo plazo de una infancia vivida en una instituciĂłn. Las historias recopiladas de 40 hombres y 41 mujeres que crecieron en una instituciĂłn en la Ă©poca de Duplessis constatan el nĂșmero elevado de abusos y experiencias adversas, incluyendo agresiones fĂsicas, psicolĂłgicas y sexuales. El medio era poco estimulante y ofrecĂa pocas oportunidades de desarrollar relaciones de apego positivas y significativas. Al emparejarlos y compararlos a los adultos provenientes de la encuesta de Salud Quebec, los niños de Duplessis, quienes ya son adultos, reportan mĂĄs problemas de salud relacionados al estrĂ©s y un desasosiego psicolĂłgico mĂĄs importante. Nuestros resultados indican tambiĂ©n que las personas que disponen de pocos recursos y aptitudes personales en su infancia son las mĂĄs afectadas por las experiencias adversas.As conseqĂŒĂȘncias negativas de uma internação em instituição sobre as crianças foram documentadas, mas nenhum estudo foi realizado sobre os ĂłrfĂŁos e as crianças internadas quando jĂĄ se tornaram adultas. No Quebec, as âcrianças de Duplessisâ testemunham de maneira profunda das repercussĂ”es a longo prazo de uma infĂąncia vivida em instituição. As histĂłrias recolhidas junto a 40 homens e 41 mulheres que cresceram em instituição na Ă©poca do governo de Duplessis relatam um alto nĂșmero de abusos e de experiĂȘncias adversas, incluindo agressĂ”es fĂsicas, psicolĂłgicas e sexuais. O meio era pouco estimulante e oferecia poucas oportunidades de desenvolver relaçÔes de apego positivas e significativas. Quando eles foram colocados lado a lado e comparados aos adultos vindos da pesquisa de SantĂ©-QuĂ©bec, as âcrianças de Duplessisâ que se tornaram adultas sofrem mais de problemas de saĂșde ligados ao estresse e a uma depressĂŁo psicolĂłgica mais importante. Nossos resultados indicam igualmente que as pessoas que dispuseram de poucos recursos e aptidĂ”es pessoais na infĂąncia sĂŁo mais afetadas pelas experiĂȘncias adversas
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Slope of the intracranial pressure waveform after traumatic brain injury.
BackgroundThe measurement and treatment of ICP within the management of TBI generally focuses on keeping the mean ICP to less than 20 mm Hg. More sophisticated analysis of the intracranial pressure waveform has yielded important relationships, but those methods have not gained widespread use. Prior analysis of the slope of the ICP waveform during inspiration and expiration in patients with hydrocephalus has provided valuable information that has never been applied to patients with TBI. This study used digital methods to examine ICP and the slope of the ICP waveform in relation to the respiratory cycle in subjects with TBI.MethodsIntracranial pressure was monitored in 6 randomly selected patients admitted with acute TBI. In the first 3 subjects, a single 5-minute recording was analyzed. In 3 subsequent subjects, 4 nonsequential 5-minute epochs were analyzed during periods of varying ICP. The systolic slope of the ICP waveform was compared during inspiration and expiration, and then evaluated in relation to simultaneous mean ICP.ResultsThe slope of the systolic ICP waveform was significantly greater during inspiration than during expiration (P < .0001 for 5 subjects and P < .03 for 1 subject). Within each subject, the ICP slope was positively correlated with simultaneous ICP (P < .0001 in all 6 cases).ConclusionGreater systolic ICP waveform slope during inspiration has not been described previously after TBI and is consistent with prior observations in subjects with hydrocephalus. The strong correlation between ICP slope and simultaneous mean ICP suggests that increasing ICP slope might indicate loss of intracranial compliance after TBI
Detection of subthreshold pulses in neurons with channel noise
Neurons are subject to various kinds of noise. In addition to synaptic noise,
the stochastic opening and closing of ion channels represents an intrinsic
source of noise that affects the signal processing properties of the neuron. In
this paper, we studied the response of a stochastic Hodgkin-Huxley neuron to
transient input subthreshold pulses. It was found that the average response
time decreases but variance increases as the amplitude of channel noise
increases. In the case of single pulse detection, we show that channel noise
enables one neuron to detect the subthreshold signals and an optimal membrane
area (or channel noise intensity) exists for a single neuron to achieve optimal
performance. However, the detection ability of a single neuron is limited by
large errors. Here, we test a simple neuronal network that can enhance the
pulse detecting abilities of neurons and find dozens of neurons can perfectly
detect subthreshold pulses. The phenomenon of intrinsic stochastic resonance is
also found both at the level of single neurons and at the level of networks. At
the network level, the detection ability of networks can be optimized for the
number of neurons comprising the network.Comment: 14 pages, 9 figure
The distribution and movement patterns of four woodland caribou herds in Quebec and Labrador
Recent studies of woodland caribou (Rangifer tarandus caribou) in northern Quebec and central Labrador have demonstrated similar patterns of seasonal movements and distribution among four herds. Aerial surveys and radio-telemetry indicated that animals occupied forest-wetland habitat at densities of 0.03 caribou km2, or lower, for most of the year. Although females were widely dispersed at calving individuals demonstrated fidelity toward specific calving locations, in successive years. Caribou did not form large post-calving aggregations. Movement was greatest in the spring, prior to calving, and in the fall, during or immediately after rutting. Caribou were generally sedentary during summer and winter, although some moved relatively long distances to late-winter range. Although the herds occupy continuous range across Quebec and Labrador, our data indicate that the herds are largely discreete and should be managed individually
Detection of Atmospheric Cherenkov Radiation Using Solar Heliostat Mirrors
The gamma-ray energy region between 20 and 250 GeV is largely unexplored.
Ground-based atmospheric Cherenkov detectors offer a possible way to explore
this region, but large Cherenkov photon collection areas are needed to achieve
low energy thresholds. This paper discusses the development of a Cherenkov
detector using the heliostat mirrors of a solar power plant as the primary
collector. As part of this development, we built a prototype detector
consisting of four heliostat mirrors and used it to record atmospheric
Cherenkov radiation produced in extensive air showers created by cosmic ray
particles.Comment: 16 latex pages, 8 postscript figures, uses psfig.sty, to be published
in Astroparticle Physic
The Cosmic Ray Background as a Tool for Relative Calibration of Atmospheric Cherenkov Telescopes
The atmosphere is an intrinsic part of any ground based Cherenkov gamma-ray
telescope, and the telescope response is therefore sensitive to unpredictable
changes in the atmospheric transparency which are difficult to measure and
interpret in the absence of a calibrated beam of high energy gamma-rays. In
this paper, we use the detector response to Cherenkov emission from cosmic ray
initiated air showers to obtain a relative calibration for data obtained under
different instrumental and atmospheric conditions as well as over a range of
source angles to the Zenith. We show that such a relative calibration is useful
and efficient for data selection, for correcting the measured gamma-ray rate
and for inter-calibration between the elements of an array of Cherenkov
telescopes.Comment: 19 pages. Accepted for publication in Astroparticle Physic
Cannabis use and risk of schizophrenia: a Mendelian randomization study.
Cannabis use is observationally associated with an increased risk of schizophrenia, but whether the relationship is causal is not known. Using a genetic approach, we took 10 independent genetic variants previously identified to associate with cannabis use in 32 330 individuals to determine the nature of the association between cannabis use and risk of schizophrenia. Genetic variants were employed as instruments to recapitulate a randomized controlled trial involving two groups (cannabis users vs nonusers) to estimate the causal effect of cannabis use on risk of schizophrenia in 34 241 cases and 45 604 controls from predominantly European descent. Genetically-derived estimates were compared with a meta-analysis of observational studies reporting ever use of cannabis and risk of schizophrenia or related disorders. Based on the genetic approach, use of cannabis was associated with increased risk of schizophrenia (odds ratio (OR) of schizophrenia for users vs nonusers of cannabis: 1.37; 95% confidence interval (CI), 1.09-1.67; P-value=0.007). The corresponding estimate from observational analysis was 1.43 (95% CI, 1.19-1.67; P-value for heterogeneity =0.76). The genetic markers did not show evidence of pleiotropic effects and accounting for tobacco exposure did not alter the association (OR of schizophrenia for users vs nonusers of cannabis, adjusted for ever vs never smoker: 1.41; 95% CI, 1.09-1.83). This adds to the substantial evidence base that has previously identified cannabis use to associate with increased risk of schizophrenia, by suggesting that the relationship is causal. Such robust evidence may inform public health messages about cannabis use, especially regarding its potential mental health consequences
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