641 research outputs found

    Impact of forestry practices on fitness correlates and population productivity in an open-nesting bird species

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    In the boreal forests of Fennoscandia, over 99% of the forest area has been altered by forestry practices, which has created forests of differing age structures and stand characteristics than primary forest stands. Although many researchers have investigated how forestry affects species abundance, few have assessed how forestry affects fitness correlates of species living in altered habitats, and this has negatively affected management efforts. We experimentally addressed the effect of standard forestry practices on fitness correlates of an open-nesting, long-lived bird species typical to boreal forests of Eurasia, the Siberian Jay (Perisoreus infaustus L.). Using a before-after comparison of reproductive data on the level of territories, we found that standard forestry practices had a strong negative effect on the breeding success of jays. Both partial thinning of territories and partial clearcutting of territories reduced future breeding success by a factor of 0.35. Forestry practices reduced territory occupancy. Thus, over the 15 years of the study the productivity of the affected population declined over 50% as a result of territory abandonment and reduced breeding success. Results of previous studies on Siberian Jays suggest that the strong effect of forest thinning on fitness is explained by the fact that most common predators of nests and adults are visually oriented, and thinning makes prey and nests more visible to predators. The consequences of thinning we observed are likely to apply to a wide range of species that rely on understory to provide visual protection from predators. Thus, our results are important for the development of effective conservation management protocols and for the refinement of thinning practices

    Electromagnetic backscattering by plates and disks

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    With the recent development of diffraction coefficients for imperfectly conducting half-planes, it has become possible to analyze a wide variety of problems for which the impedance surface boundary condition applies. This impedance boundary condition, while approximate, was utilized to extend the usefulness of the Uniform Geometrical Theory of Diffraction (UTD) beyond the perfectly conducting geometries. These half-plane diffraction coefficients are used to analyze patterns of an antenna in the presence of an imperfectly conducting flat polygonal plate. The Geometrical Theory of Diffraction (GTD) techniques were also used to investigate the backscattering from perfectly conducting plates. To further improve the soft polarization results for wide angles, a model for the creeping wave or circulating current on the edge of the disk was obtained and used to find an additional component of the backscattered field. The backscattering from a square plate was then analyzed using GTD. Backscattering in both the principal and off-principal planes was examined

    Incubating females use dynamic risk assessment to evaluate the risk posed by different predators

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    Uncertainty poses a substantial problem for animals, making it is essential for individuals to anticipate changes in their environment to select suitable behavioral strategies. In nest-building species where parents care for dependent young, predation is a major cause of reproductive failure. However, because parents generally have inadequate information about nest predation risks, attaining information about predation hazards increases their likelihood of making informed, optimal decisions. Risk assessment should therefore be widespread, particularly in incubating parents of species that breed in cavities or closed nests, which have limited information about predator presence. This study experimentally investigated the dynamic risk assessment in incubating female brown thornbill (Acanthiza pusilla), a long-lived Australian passerine, which builds closed dome nests in dense vegetation. When the females were exposed to the calls of a nest predator, a predator of adults, and a nonpredatory species, they reacted most strongly to the predator of adults' calls, by looking out of the nest for longest. Females significantly increased their level of alertness on hearing calls of both predator species and maintained their higher level of alertness after the simulated predator presence ended. Females in nests with a high degree of visual cover, and therefore a larger information deficit, reacted more strongly to predator calls than females in more open nests. Moreover, poorly concealed nests had a higher probability of being predated. These results show that incubating female thornbills use dynamic risk assessment and base their response on who is at risk and the degree of information defici

    Incubating females use dynamic risk assessment to evaluate the risk posed by different predators

    Get PDF
    Uncertainty poses a substantial problem for animals, making it is essential for individuals to anticipate changes in their environment to select suitable behavioral strategies. In nest-building species where parents care for dependent young, predation is a major cause of reproductive failure. However, because parents generally have inadequate information about nest predation risks, attaining information about predation hazards increases their likelihood of making informed, optimal decisions. Risk assessment should therefore be widespread, particularly in incubating parents of species that breed in cavities or closed nests, which have limited information about predator presence. This study experimentally investigated the dynamic risk assessment in incubating female brown thornbill (Acanthiza pusilla), a long-lived Australian passerine, which builds closed dome nests in dense vegetation. When the females were exposed to the calls of a nest predator, a predator of adults, and a nonpredatory species, they reacted most strongly to the predator of adults' calls, by looking out of the nest for longest. Females significantly increased their level of alertness on hearing calls of both predator species and maintained their higher level of alertness after the simulated predator presence ended. Females in nests with a high degree of visual cover, and therefore a larger information deficit, reacted more strongly to predator calls than females in more open nests. Moreover, poorly concealed nests had a higher probability of being predated. These results show that incubating female thornbills use dynamic risk assessment and base their response on who is at risk and the degree of information defici

    Dapsone Form V: A Late Appearing Thermodynamic Polymorph of a Pharmaceutical

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    Five anhydrate polymorphs (forms I–V) and the isomorphic dehydrate (Hy_{dehy}) of dapsone (4,4′-diaminodiphenyl sulfone or DDS) were prepared and characterized in an interdisciplinary experimental and computational study, elucidating the kinetic and thermodynamic stabilities, solid form interrelationships, and structural features of the known forms I–IV, the novel polymorph form V, and Hy_{dehy}. Calorimetric measurements, solubility experiments, and lattice energy calculations revealed that form V is the thermodynamically stable polymorph from absolute zero to at least 90 °C. At higher temperatures, form II, and then form I, becomes the most stable DDS solid form. The computed 0 K stability order (lattice energy calculations) was confirmed with calorimetric measurements as follows, V (most stable) > III > Hy_{dehy} > II > I > IV (least stable). The discovery of form V was complicated by the fact that the metastable but kinetically stabilized form III shows a higher nucleation and growth rate. By combining laboratory powder X-ray diffraction data and ab initio calculations, the crystal structure of form V (P2_{1} /c, Z′ = 4) was solved, with a high energy DDS conformation allowing a denser packing and more stable intermolecular interactions, rationalizing the formation of a high Z′ structure. The structures of the forms I and IV, only observed from the melt and showing distinct packing features compared to the forms II, III, and V, were derived from the computed crystal energy landscapes. Dehydration modeling of the DDS hydrate led to the Hydehy structure. This study expands our understanding about the complex crystallization behavior of pharmaceuticals and highlights the big challenge in solid form screening, especially that there is no clear end point

    Family living: an overlooked but pivotal social system to understand the evolution of cooperative breeding

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    Bird breeding systems are more diverse than previously appreciated. Here we show that defining an intermediate breeding system, family breeding, where individuals postpone their dispersal but do not cooperate in reproduction, is a natural extension of the widely accepted 2-category system (pair vs. cooperative breeding). Evolution of prolonged association of offspring with parents appears to be possible in cases where it extends into unfavorable periods of environmental conditions such as autumn/winte

    Structural Properties, Order-Disorder Phenomena and Phase Stability of Orotic Acid Crystal Forms

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    Orotic acid (OTA) is reported to exist in the anhydrous (AH), monohydrate (Hy1) and dimethylsulfoxide monosolvate (SDMSO) forms. In this study we investigate the (de)hydration/desolvation behavior, aiming at an understanding of the elusive structural features of anhydrous OTA by a combination of experimental and computational techniques, namely, thermal analytical methods, gravimetric moisture (de)sorption studies, water activity measurements, X-ray powder diffraction, spectroscopy (vibrational, solid-state NMR), crystal energy landscape and chemical shift calculations. The Hy1 is a highly stable hydrate, which dissociates above 135°C and loses only a small part of the water when stored over desiccants (25°C) for more than one year. In Hy1, orotic acid and water molecules are linked by strong hydrogen bonds in nearly perfectly planar arranged stacked layers. The layers are spaced by 3.1 Å and not linked via hydrogen-bonds. Upon dehydration the X-ray powder diffraction and solid-state NMR peaks become broader indicating some disorder in the anhydrous form. The Hy1 stacking reflection (122) is maintained, suggesting that the OTA molecules are still arranged in stacked layers in the dehydration product. Desolvation of SDMSO, a non-layer structure, results in the same AH phase as observed upon dehydrating Hy1. Depending on the desolvation conditions different levels of order-disorder of layers present in anhydrous OTA are observed, which is also suggested by the computed low energy crystal structures. These structures provide models for stacking faults as intergrowth of different layers is possible. The variability in anhydrate crystals is of practical concern as it affects the moisture dependent stability of AH with respect to hydration

    Prediction of potentially avoidable readmission risk in a division of general internal medicine.

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    The 30-day post-discharge readmission rate is a quality indicator that may reflect suboptimal care. The computerised algorithm SQLape® can retrospectively identify a potentially avoidable readmission (PARA) with high sensitivity and specificity. We retrospectively analysed the hospital stays of patients readmitted to the Department of Internal Medicine of the CHUV (Centre Hospitalier Universitaire Vaudois) in order to quantify the proportion of PARAs and derive a risk prediction model. All hospitalisations between January 2009 and December 2011 in our division of general internal medicine were analysed. Readmissions within 30 days of discharge were categorised using SQLape®. The impact on PARAs was tested for various clinical and nonclinical factors. The performance of the developed model was compared with the well-validated LACE and HOSPITAL scores. From a total of 11 074 hospital stays, 777 (7%) were followed with PARA within 30 days. By analysing a group of 6729 eligible stays, defined in particular by the patients' returning to their place of residence (home or residential care centre), we identified the following risk factors: ≥1 hospitalisation in the year preceding index admission, Charlson score >1, active cancer, hyponatraemia, length of stay >11 days, prescription of ≥15 different medications during the stay. These variables were used to derive a risk prediction model for PARA with a good discriminatory power (C-statistic 0.70) and calibration (p = 0.69). Patients were then classified as low (16.4%), intermediate (49.4%) or high (34.2%) risk of PARA. The estimated risk of PARA for each category was 3.5%, 8.7% and 19.6%, respectively. The LACE and the HOSPITAL scores were significantly correlated with the PARA risk. The discriminatory power of the LACE (C-statistic 0.61) and the HOSPITAL (C-statistic 0.54) were lower than our model. Our model identifies patients at high risk of 30-day PARA with a good performance. It could be used to target transition of care interventions. Nevertheless, this model should be validated on more data and could be improved with additional parameters. Our results highlight the difficulty to generalise one model in the context of different healthcare systems

    Cost-Benefit Analysis of the Implementation of an Enhanced Recovery Program in Liver Surgery.

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    BACKGROUND: Enhanced recovery after surgery (ERAS) programs have been shown to ease the postoperative recovery and improve clinical outcomes for various surgery types. ERAS cost-effectiveness was demonstrated for colorectal surgery but not for liver surgery. The present study aim was to analyze the implementation costs and benefits of a specific ERAS program in liver surgery. METHODS: A dedicated ERAS protocol for liver surgery was implemented in our department in July 2013. The subsequent year all consecutive patients undergoing liver surgery were treated according to this protocol (ERAS group). They were compared in terms of real in-hospital costs with a patient series before ERAS implementation (pre-ERAS group). Mean costs per patient were compared with a bootstrap T test. A cost-minimization analysis was performed. RESULTS: Seventy-four ERAS patients were compared with 100 pre-ERAS patients. There were no significant pre- and intraoperative differences between the two groups, except for the laparoscopy number (n = 18 ERAS, n = 9 pre-ERAS, p = 0.010). Overall postoperative complications were observed in 36 (49 %) and 64 patients (64 %) in the ERAS and pre-ERAS groups, respectively (p = 0.046). The median length of stay was significantly shorter for the ERAS group (8 vs. 10 days, p = 0.006). The total mean costs per patient were euro38,726 and euro42,356 for ERAS and pre-ERAS (p = 0.467). The cost-minimization analysis showed a total mean cost reduction of euro3080 per patient after ERAS implementation. CONCLUSIONS: ERAS implementation for liver surgery induced a non-significant decrease in cost compared to standard care. Significant decreased complication rate and hospital stay were observed in the ERAS group
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