Broad scale population estimates of declining species are desired for conservation efforts. However, for many secretive species including large carnivores, such estimates are often difficult. Based ...on published density estimates obtained through camera trapping, presence/absence data, and globally available predictive variables derived from satellite imagery, we modelled density and occurrence of a large carnivore, the jaguar, across the species' entire range. We then combined these models in a hierarchical framework to estimate the total population. Our models indicate that potential jaguar density is best predicted by measures of primary productivity, with the highest densities in the most productive tropical habitats and a clear declining gradient with distance from the equator. Jaguar distribution, in contrast, is determined by the combined effects of human impacts and environmental factors: probability of jaguar occurrence increased with forest cover, mean temperature, and annual precipitation and declined with increases in human foot print index and human density. Probability of occurrence was also significantly higher for protected areas than outside of them. We estimated the world's jaguar population at 173,000 (95% CI: 138,000-208,000) individuals, mostly concentrated in the Amazon Basin; elsewhere, populations tend to be small and fragmented. The high number of jaguars results from the large total area still occupied (almost 9 million km2) and low human densities (< 1 person/km2) coinciding with high primary productivity in the core area of jaguar range. Our results show the importance of protected areas for jaguar persistence. We conclude that combining modelling of density and distribution can reveal ecological patterns and processes at global scales, can provide robust estimates for use in species assessments, and can guide broad-scale conservation actions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Natal dispersal promotes inter-population linkage, and is key to spatial distribution of populations. Degradation of suitable landscape structures beyond the specific threshold of an individual's ...ability to disperse can therefore lead to disruption of functional landscape connectivity and impact metapopulation function. Because it ignores behavioral responses of individuals, structural connectivity is easier to assess than functional connectivity and is often used as a surrogate for landscape connectivity modeling. However using structural resource selection models as surrogate for modeling functional connectivity through dispersal could be erroneous. We tested how well a second-order resource selection function (RSF) models (structural connectivity), based on GPS telemetry data from resident adult leopard (
Panthera pardus
L.), could predict subadult habitat use during dispersal (functional connectivity). We created eight non-exclusive subsets of the subadult data based on differing definitions of dispersal to assess the predictive ability of our adult-based RSF model extrapolated over a broader landscape. Dispersing leopards used habitats in accordance with adult selection patterns, regardless of the definition of dispersal considered. We demonstrate that, for a wide-ranging apex carnivore, functional connectivity through natal dispersal corresponds to structural connectivity as modeled by a second-order RSF. Mapping of the adult-based habitat classes provides direct visualization of the potential linkages between populations, without the need to model paths between a priori starting and destination points. The use of such landscape scale RSFs may provide insight into predicting suitable dispersal habitat peninsulas in human-dominated landscapes where mitigation of human-wildlife conflict should be focused. We recommend the use of second-order RSFs for landscape conservation planning and propose a similar approach to the conservation of other wide-ranging large carnivore species where landscape-scale resource selection data already exist.
1. Emerging conservation paradigms have shifted from single to multi-species approaches focused on sustaining biodiversity. Multi-species hierarchical occupancy modelling provides a method for ...assessing biodiversity while accounting for multiple sources of uncertainty. 2. We analysed camera trapping data with multi-species models using a Bayesian approach to estimate the distributions of a terrestrial mammal community in northern Botswana and evaluate community, group, and species-specific responses to human disturbance and environmental variables. Groupings were based on two life-history traits: body size (small, medium, large and extra-large) and diet (carnivore, omnivore and herbivore). 3. We photographed 44 species of mammals over 6607 trap nights. Camera station-specific estimates of species richness ranged from 8 to 27 unique species, and species had a mean occurrence probability of 0·32 (95% credible interval = 0·21-0·45). At the community level, our model revealed species richness was generally greatest in floodplains and grasslands and with increasing distances into protected wildlife areas. 4. Variation among species' responses was explained in part by our species groupings. The positive influence of protected areas was strongest for extra-large species and herbivores, while medium-sized species actually increased in the non-protected areas. The positive effect of grassland/floodplain cover, alternatively, was strongest for large species and carnivores and weakest for small species and herbivores, suggesting herbivore diversity is promoted by habitat heterogeneity. 5. Synthesis and applications. Our results highlight the importance of protected areas and grasslands in maintaining biodiversity in southern Africa. We demonstrate the utility of hierarchical Bayesian models for assessing community, group and individual species' responses to anthropogenic and environmental variables. This framework can be used to map areas of high conservation value and predict impacts of land-use change. Our approach is particularly applicable to the growing number of camera trap studies world-wide, and we suggest broader application globally will likely result in reduced costs, improved efficiency and increased knowledge of wildlife communities.
Background The use of bilateral internal thoracic arteries (BITA) in coronary artery bypass graft surgery improves patient survival. The optimum BITA graft configuration is unknown. This study ...evaluates outcomes after the use of bilateral internal mammary Y grafting as the primary grafting strategy. Methods Patients who underwent BITA composite Y grafting (n = 1,011) between October 1994 and March 2009 were identified from a cardiac surgical database. Follow-up (mean 12 years) was obtained by cross-reference with the state death registry and local cardiology databases. Results Perioperative mortality was 1.6%. Kaplan-Meier 10-year survival was 87.2%. There were 464 episodes of postdischarge angiography in 296 patients, at an average of 5.5 years to first angiography. Graft failure occurred in 151 patients, predominately affecting the right ITA limb (n = 139). Degree of native vessel stenosis (odds ratio OR 0.66 per 10% increase), anatomic territory grafted (circumflex OR 2.64, right coronary OR 6.73 versus anterior), and end-to-side free wall anastomoses (OR 1.98) predicted anastomotic occlusion. The left anterior descending artery graft patency was unaffected by sequential grafting. Progression to graft failure after the first angiogram was rarely seen in the 111 patients who had serial angiography. Conclusions Outcomes of BITA Y grafting are similar to those for other BITA configurations. The rate of presentation with arterial graft dysfunction decreases over time. Although competitive flow affects anastomotic patency, there is no threshold at which risk of occlusion substantially increases.
Understanding the relationship between foraging ecology and the presence of human-dominated landscapes is important, particularly for American black bears (Ursus americanus), which sometimes move ...between wildlands and urban areas to forage. The food-related factors influencing this movement have not been explored, but can be important for understanding the benefits and costs to black bear foraging behavior and the fundamental origins of bear conflicts. We tested whether the scarcity of wildland foods or the availability of urban foods can explain when black bears forage near houses, examined the extent to which male bears use urban areas in comparison to females, and identified the most important food items influencing bear movement into urban areas. We monitored 16 collared black bears in and around Missoula, Montana, during 2009 and 2010, while quantifying the rate of change in green vegetation and the availability of 5 native berry-producing species outside the urban area, the rate of change in green vegetation, and the availability of apples and garbage inside the urban area. We used parametric time-to-event models in which an event was a bear location collected within 100 m of a house. We also visited feeding sites located near houses and quantified food items bears had eaten. The probability of a bear being located near a house was 1.6 times higher for males, and increased during apple season and the urban green-up. Fruit trees accounted for most of the forage items at urban feeding sites (49%), whereas wildland foods composed <10%. Black bears foraged on human foods near houses even when wildland foods were available, suggesting that the absence of wildland foods may not influence the probability of bears foraging near houses. Additionally, other attractants, in this case fruit trees, appear to be more important than the availability of garbage in influencing when bears forage near houses.
Summary Background Up to 50% of patients with acute stroke are taking antihypertensive drugs on hospital admission. However, whether such treatment should be continued during the immediate ...post-stroke period is unclear. We therefore aimed to assess the efficacy and safety of continuing or stopping pre-existing antihypertensive drugs in patients who had recently had a stroke. Methods The Continue Or Stop post-Stroke Antihypertensives Collaborative Study (COSSACS) was a UK multicentre, prospective, randomised, open, blinded-endpoint trial. Patients were recruited at 49 UK National Institute for Health Research Stroke Research Network centres from January 1, 2003, to March 31, 2009. Patients aged over 18 years who were taking antihypertensive drugs were enrolled within 48 h of stroke and the last dose of antihypertensive drug. Patients were randomly assigned (1:1) by secure internet central randomisation to either continue or stop pre-existing antihypertensive drugs for 2 weeks. Patients and clinicians who randomly assigned patients were unmasked to group allocation. Clinicians who assessed 2-week outcomes and 6-month outcomes were masked to group allocation. The primary endpoint was death or dependency at 2 weeks, with dependency defined as a modified Rankin scale score greater than 3 points. Analysis was by intention to treat. This trial is registered with the International Standard Randomised Controlled Trial Register , number ISRCTN89712435. Findings 763 patients were assigned to continue (n=379) or stop (n=384) pre-existing antihypertensive drugs. 72 of 379 patients in the continue group and 82 of 384 patients in the stop group reached the primary endpoint (relative risk 0·86, 95% CI 0·65–1·14; p=0·3). The difference in systolic blood pressure at 2 weeks between the continue group and the stop group was 13 mm Hg (95% CI 10–17) and the difference in diastolic blood pressure was 8 mm Hg (6–10; difference between groups p<0·0001). No substantial differences were observed between groups in rates of serious adverse events, 6-month mortality, or major cardiovascular events. Interpretation Continuation of antihypertensive drugs did not reduce 2-week death or dependency, cardiovascular event rate, or mortality at 6 months. Lower blood pressure levels in those who continued antihypertensive treatment after acute mild stroke were not associated with an increase in adverse events. These neutral results might be because COSSACS was underpowered owing to early termination of the trial, and support the continuation of ongoing research trials. Funding The Health Foundation and The Stroke Association.
Estimating abundance of wildlife populations can be challenging and costly, especially for species that are difficult to detect and that live at low densities, such as cougars (Puma concolor). ...Remote, motion-sensitive cameras are a relatively efficient monitoring tool, but most abundance estimation techniques using remote cameras rely on some or all of the population being uniquely identifiable. Recently developed methods estimate abundance from encounter rates with remote cameras and do not require identifiable individuals. We used 2 methods, the time-to-event and space-to-event models, to estimate the density of 2 cougar populations in Idaho, USA, over 3 winters from 2016–2019. We concurrently estimated cougar density using the random encounter model (REM), an existing camera-based method for unmarked populations, and genetic spatial capture recapture (SCR), an established method for monitoring cougar populations. In surveys for which we successfully estimated density using the SCR model, the time-to-event estimates were more precise and showed comparable variation between survey years. The space-to-event estimates were less precise than the SCR estimates and were more variable between survey years. Compared to REM, time-to-event was more precise and consistent, and space-to-event was less precise and consistent. Low sample sizes made the space-to-event and SCR models inconsistent from survey to survey, and nonrandom camera placement may have biased both of the camera-based estimators high. We show that camera-based estimators can perform comparably to existing methods for estimating abundance in unmarked species that live at low densities. With the time- and space-to-event models, managers could use remote cameras to monitor populations of multiple species at broader spatial and temporal scales than existing methods allow.
Concurrent monitoring of multiple species with a single study design can be an efficient use of time and financial resources. Using camera traps to estimate density or abundance of multiple species ...is only possible if the study design captures photographs of all target species in an unbiased manner. We used camera trap data originally collected for a different purpose and applied the Space to Event (STE) model to estimate density of multiple species simultaneously. We had sufficient data to estimate densities of moose (Alces alces), black bear (Ursus americanus), mountain lions (Puma concolor), wolves (Canis lupus), and deer (white‐tailed deer Odocoileus virginianus and mule deer O. hemionus combined). Our estimated densities were lower than those derived from other methods in the study area, possibly due to the lack of a sampling design specific to STE. However, our estimates were generally comparable to published density estimates from across the species' range. Our approach allowed us to estimate abundance and density for each species with the same effort required to estimate abundance of a single species. Our results suggest that with an appropriate study design, STE could be an effective, efficient, low cost and non‐invasive method for estimating densities of multiple unmarked species using a single camera array.
We applied a new model, Space to Event (STE), to estimate density and abundance of multiple species non‐invasively and without the need for individually identifiable animals. We used camera trap data originally collected for a different purpose to test whether this new model could estimate multiple species simultaneously from a single camera array. Our results suggest that with an appropriate study design, STE could be an effective, efficient, low cost and non‐invasive method for estimating densities of multiple unmarked species using a single camera array.
Outcomes of cardiac surgery in chronic kidney disease Fernando, Mangalee, FRACP; Paterson, Hugh S., FRACS; Byth, Karen, PhD ...
The Journal of thoracic and cardiovascular surgery,
11/2014, Letnik:
148, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Objective To identify predictors of early and late outcomes of cardiac surgery in patients with chronic kidney disease. Methods Patients (n = 545) with serum creatinine ≥200 μmol/L or renal dialysis ...were identified from databases maintained by the largest Sydney cardiothoracic surgical units with data consistent with the Australian and New Zealand Society of Cardiothoracic Surgeons data definitions. The patient data were matched against the National Dialysis Database and the New South Wales Register of Births, Deaths, and Marriages. Statistical analysis was used to identify predictors of early and late outcomes. Results The Kaplan-Meier estimate of 1-, 5-, and 10-year survival for all patients was 78%, 56%, and 36%, respectively. The outcomes were similar after coronary bypass surgery and valve replacement and were also similar for dialysis and nondialysis patients. The odds ratios for the significant independent predictors of outcomes were, for perioperative death, age (1.4 per decade), emergency surgery (7.0), redo surgery (3.8), left ventricular impairment (moderate, 2.7; severe, 4.4); for new early postoperative dialysis, estimated glomerular filtration rate <20 mL/min (3.8), emergency surgery (2.7), tricuspid valve surgery (4.4); for new permanent dialysis within 6 months of surgery, serum estimated glomerular filtration rate <20 mL/min (odds ratio, 4.6). The hazard ratio for the independent predictors of late death in those alive 6 months after surgery was 1.4 per decade for age and 1.4 for moderate or severe left ventricular impairment. Conclusions Left ventricular impairment is a risk factor for perioperative and late death in patients with kidney disease. After cardiac surgery, preoperative dialysis-dependent and dialysis-free patients had similar long-term outcomes.
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