3,431 research outputs found
Factors limiting productivity of the Central Arctic Caribou Herd of Alaska
Many biotic and abiotic factors can limit productivity and growth of caribou (Rangifer tarandus) herds, but limiting factors typically vary by region. Identifying limiting factors may help to indicate which seasons are of relative importance to a caribou herd and possibly to suggest general life history strategies. Using regression techniques, we found that despite previous suggestions, net productivity of Alaska’s Central Arctic Caribou Herd (CAH) did not respond to early summer forage biomass or summer insect severity from the previous year. Abiotic factors that did have apparent effects on CAH productivity included early fall snow deposition, winter snow condition, and spring snow ablation. To achieve a suitable weight for conception, caribou of the CAH may exhibit a seasonal time-minimizing foraging strategy by moderating weight gain during the warm summer insect season and feeding more intensively during the insect-free weeks before the autumn rut. A long-term trend of the Northern Hemisphere annular mode (NAM) may be linked to anthropogenic climate change and may have negative implications for the future success of the CAH
Differential impact of two risk communications on antipsychotic prescribing to people with dementia in Scotland: segmented regression time series analysis 2001-2011
The two risk communications were associated with reductions in antipsychotic use, in ways which were compatible with marked differences in their content and dissemination. Further research is needed to ensure that the content and dissemination of regulatory risk communications is optimal, and to track their impact on intended and unintended outcomes. Although rates are falling, antipsychotic prescribing in dementia in Scotland remains unacceptably hig
Run-in periods and clinical outcomes of antipsychotics in dementia:A meta-epidemiological study of placebo-controlled trials
PURPOSE: Run-in periods are used to identify placebo-responders and washout. Our aim was to assess the association of run-in periods with clinical outcomes of antipsychotics in dementia. METHODS: We searched randomized placebo-controlled trials of conventional and atypical antipsychotics for neuropsychiatric symptoms (NPS) in dementia in electronic sources and references of selected articles. We extracted (a) the presence of a run-in period, use of placebo/investigated drug during run-in (versus washout only), and run-in duration (1 week or more) and (b) the reduction in NPS, number of participants with somnolence, extrapyramidal symptoms (EPS), and deaths per treatment group. We pooled clinical outcomes comparing antipsychotic and placebo groups in trials with and without run-in. RESULTS: We identified 35 trials. Twenty-nine trials used run-in. The pooled standardized mean difference in the reduction of NPS was -0.170 (95% CI, -0.227 to -0.112) in trials with run-in and -0.142 (95% CI, -0.331 to 0.047) in trials without run-in. The pooled odds ratio for somnolence was 2.8 (95% CI, 2.3-3.5) in trials with run-in and 3.5 (95% CI, 1.2-10.7) in trials without run-in; for EPS, these ORs were 1.8 (95% CI, 1.4-2.2) and 2.0 (95% CI, 1.3-3.1) respectively, and for mortality 1.4 (95% CI, 1.0-2.0) and 1.6 (95% CI, 0.7-3.4). The use of placebo/investigated drug during run-in and run-in duration did not affect the estimates in a consistent way. CONCLUSIONS: The use of run-in in trials might have led to overestimated efficacy and especially underestimated risks of side effects of antipsychotics compared with placebo for NPS in dementia
UK sustainable drainage systems: past, present and future
Urban drainage has developed from an engineering discipline, concerned principally with public health and safety outcomes, into a multifaceted vision linking drainage with environmental and wider social and economic imperatives to deliver multifunctional outcomes. UK attention is too often focused on surface water as âa problemâ, despite international progress and initiatives showing that an âopportunity-centredâ approach needs to be taken. Sustainable drainage systems, or âSudsâ, can, when they are part of an integrated approach to water management, cost-effectively provide many benefits beyond management of water quality and quantity. New tools are available that can design Suds for maximum value to society but this requires greater collaboration across disciplines to seize all of the opportunities available. This paper introduces those tools and a roadmap for their use, including guidance, design objectives and criteria for maximising benefits. These new supporting tools and guidance can help to provide a business case for greater use of Suds in future
Cosmic Ray Acceleration at Relativistic Shock Waves with a "Realistic" Magnetic Field Structure
The process of cosmic ray first-order Fermi acceleration at relativistic
shock waves is studied with the method of Monte Carlo simulations. The
simulations are based on numerical integration of particle equations of motion
in a turbulent magnetic field near the shock. In comparison to earlier studies,
a few "realistic" features of the magnetic field structure are included. The
upstream field consists of a mean field component inclined at some angle to the
shock normal with finite-amplitude sinusoidal perturbations imposed upon it.
The perturbations are assumed to be static in the local plasma rest frame.
Their flat or Kolmogorov spectra are constructed with randomly drawn wave
vectors from a wide range . The downstream field structure
is derived from the upstream one as compressed at the shock. We present
particle spectra and angular distributions obtained at mildly relativistic sub-
and superluminal shocks and also parallel shocks. We show that particle spectra
diverge from a simple power-law, the exact shape of the spectrum depends on
both the amplitude of the magnetic field perturbations and the wave power
spectrum. Features such as spectrum hardening before the cut-off at oblique
subluminal shocks and formation of power-law tails at superluminal ones are
presented and discussed. At parallel shocks, the presence of finite-amplitude
magnetic field perturbations leads to the formation of locally oblique field
configurations at the shock and the respective magnetic field compressions.
This results in the modification of the particle acceleration process,
introducing some features present in oblique shocks, e.g., particle reflections
from the shock. We demonstrate for parallel shocks a (nonmonotonic) variation
of the particle spectral index with the turbulence amplitude.Comment: revised version (37 pages, 13 figures
Dynamic Responses of Calving Caribou to Oilfields in Northern Alaska
Past research has suggested that during the calving period, caribou (Rangifer tarandus) in Arctic Alaska generally avoid areas within 1 km of oilfield roads with traffic. However, avoidance is not absolute, and caribou may habituate to infrastructure (e.g., buildings, roads, well pads) and human activity. We conducted road-based surveys of caribou in oilfields on Alaskaâs Arctic Coastal Plain during the late calving and post-calving periods of June in 2000â02. We recorded location, composition, and behavior of caribou groups located less than 1 km from active gravel roads and production pads. Caribou groups with calves were on average distributed farther from oilfield infrastructure than were groups without calves, but habituation to oilfield activities, indicated by decreased avoidance, occurred at similar rates for groups with and without calves. During the calving period, sighting rates were greater in areas of low human activity, and calf percentages tended to be greater at night when oilfield activity was reduced. Caribou groups were on average closer to infrastructure during the post-calving periods than during the calving periods in 2000 and 2001, but not in 2002. In 2002, when snow melted early, caribou groups were closer to infrastructure during the calving period than in 2000 and 2001, when snow melted later, emphasizing the importance of examining environmental variables when investigating the dynamic interactions of caribou and oilfields. Overall, caribou appeared to habituate to active oilfield infrastructure after the calving period in 2000, late in the calving period in 2001, and likely before our sampling period in 2002. The timing of annual rehabituation was positively correlated with timing of spring snowmelt. Land and wildlife managers can use information from this study to develop calving period-specific mitigation measures that are more effective and flexible.Selon des recherches antĂ©rieures, pendant sa pĂ©riode de vĂȘlage, le caribou (Rangifer tarandus) de lâAlaska arctique Ă©vite gĂ©nĂ©ralement les rĂ©gions se trouvant Ă lâintĂ©rieur dâun kilomĂštre des routes oĂč circulent des vĂ©hicules menant aux chantiers pĂ©troliers. Cependant, cet Ă©vitement nâest pas absolu, et le caribou peut sâaccoutumer aux infrastructures (comme les bĂątiments, les routes et les chantiers) et Ă lâactivitĂ© humaine. Nous avons effectuĂ© le dĂ©nombrement des caribous prĂšs des routes des champs de pĂ©trole de la plaine cĂŽtiĂšre arctique de lâAlaska vers la fin de la pĂ©riode de vĂȘlage et aprĂšs la pĂ©riode de vĂȘlage de juin 2000 Ă 2002. Nous avons consignĂ© lâemplacement, la composition et le comportement des groupes de caribous se trouvant Ă moins dâun kilomĂštre des routes de gravier et des chantiers de production en activitĂ©. En moyenne, les caribous qui avaient des petits se tenaient plus loin des infrastructures pĂ©troliĂšres que les groupes de caribous qui nâavaient pas de petits. Cela dit, lâaccoutumance aux activitĂ©s pĂ©troliĂšres, dĂ©notĂ©e par un moins grand Ă©vitement, survenait Ă des taux semblables pour les groupes qui avaient des petits et les groupes qui nâen avaient pas. Pendant la pĂ©riode de vĂȘlage, les taux dâobservation de caribous Ă©taient plus Ă©levĂ©s dans les rĂ©gions oĂč il y avait peu dâactivitĂ© humaine, et les pourcentages de petits avaient tendance Ă ĂȘtre plus Ă©levĂ©s la nuit, lorsquâil y avait peu de va-et-vient aux chantiers. En moyenne, les groupes de caribous sâapprochaient plus des infrastructures pendant les pĂ©riodes suivant le vĂȘlage des annĂ©es 2000 et 2001, mais pas en 2002. En 2002, quand la neige a fondu plus tĂŽt que dâhabitude, les groupes de caribous sâapprochaient plus des infrastructures pendant la pĂ©riode de vĂȘlage quâen 2000 et 2001, lorsque la neige a fondu plus tard. Cela fait ressortir lâimportance de tenir compte des variables environnementales lorsque nous faisons des enquĂȘtes sur les interactions dynamiques entre les caribous et les champs de pĂ©trole. Dans lâensemble, les caribous semblaient sâaccoutumer aux infrastructures pĂ©troliĂšres en activitĂ© aprĂšs la pĂ©riode de vĂȘlage en 2000, puis vers la fin de la pĂ©riode de vĂȘlage en 2001, et vraisemblablement avant notre pĂ©riode dâĂ©chantillonnage en 2002. Le moment de lâaccoutumance annuelle coĂŻncidait positivement avec le moment de la fonte des neiges au printemps. Les gestionnaires des terres et de la faune peuvent se servir de lâinformation Ă©manant de cette Ă©tude pour Ă©laborer des mesures dâattĂ©nuation tenant compte de la pĂ©riode de vĂȘlage, mesures qui sont plus efficaces et qui prĂ©sentent plus de souplesse
Polygenic Risk Scoring is an Effective Approach to Predict Those Individuals Most Likely to Decline Cognitively Due to Alzheimerâs Disease
BACKGROUND: There is a clear need for simple and effective tests to identify individuals who are most likely to develop Alzheimerâs Disease (AD) both for the purposes of clinical trial recruitment but also for improved management of patients who may be experiencing early pre-clinical symptoms or who have clinical concerns. OBJECTIVES: To predict individuals at greatest risk of progression of cognitive impairment due to Alzheimerâs Disease in individuals from the Alzheimerâs Disease Neuroimaging Initiative (ADNI) using a polygenic risk scoring algorithm. To compare the performance of a PRS algorithm in predicting cognitive decline against that of using the pTau/AĂ1-42 ratio CSF biomarker profile. DESIGN: A longitudinal analysis of data from the Alzheimerâs Disease Neuroimaging Initiative study conducted across over 50 sites in the US and Canada. SETTING: Multi-center genetics study. PARTICPANTS: 515 subjects who upon entry to the study were diagnosed as cognitively normal or with mild cognitive impairment. MEASUREMENTS: Use of genotyping and/or whole genome sequencing data to calculate polygenic risk scores and assess ability to predict subsequent cognitive decline as measured by CDR-SB and ADAS-Cog13 over 4 years RESULTS: The overall performance for predicting those individuals who would decline by at least 15 ADAS-Cog13 points from a baseline mild cognitive impairment in 4 years was 72.8% (CI:67.9-77.7) AUC increasing to 79.1% (CI: 75.6-82.6) when also including cognitively normal participants. Assessing mild cognitive impaired subjects only and using a threshold of greater than 0.6, the high genetic risk participant group declined, on average, by 1.4 points (CDR-SB) more than the low risk group over 4 years. The performance of the PRS algorithm tested was similar to that of the pTau/AĂ1-42 ratio CSF biomarker profile in predicting cognitive decline. CONCLUSION: Calculating polygenic risk scores offers a simple and effective way, using DNA extracted from a simple mouth swab, to select mild cognitively impaired patients who are most likely to decline cognitively over the next four years
Between the Natural and the Artificial: The Sublime Sexual Sensation of Car Crashes in J.G. Ballardâs Crash
At a time when technology progressively pushes back nature, the sexual act runs the risk of being denaturalised. The notion of the sublime, which I argue is how humans react to the machine as a surrogate for nature and as a sexual stimulus in Crash (1973), is therefore of central interest in this article. Ballard himself has described Crash as âthe first pornographic novel based on technologyâ (1973, 6). This engagement with a technologised sexuality is explored as a subjective narrative stance, which grants authenticity to the fictive alter ego, who can probe alternatives to an extra-textual reality. This narrative mode is notably potent in relation to the narratorâs estimation of the merge between sexuality and technology in the form of car crashes uniting Eros and Thanatos. I therefore suggest that Crash can be read as an attempt to localise the natural and human in a world dictated by artificiality and technology
Antibodies to Chlamydia trachomatis in patients presenting with ectopic pregnancy at Groote Schuur hospital
Objectives. To detennine the prevalence of antibodies to Chlamydia trachomatis in women presenting with ectopic pregnancies to Groote Schuur Hospital.Methods. C. trachomatis antibody titres were measured using a modified micro-immunofluorescence test in women presenting with ectopic pregnancy. Control subjects were drawn from women with term pregnancies and an uneventful reproductive history.Results. Seventy-four patients and controls were studied. Demographic variables were controlled for at time of entry into the study. A significant association between the number of lifetime sexual partners and exposure to C. trachomatis was noted (P = 0.001). Patients with ectopic pregnancies had significantly higher antibody titres than control subjects (P = 0.001), and in both groups the prevalence of background antichlamydial antibody was high (ectopic pregnancies 59%, pregnant controls 32%).Conclusions. While the role of C. trachomatis infection in women who develop ectopic pregnancies needs to be explored further, it seems wise to treat them all with empirical antibiotics at the time of presentation
- âŠ