300 research outputs found

    The Effects of Beetle-Induced Tree Death on Forest Bird Diversity in Western Montana

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    In forest ecosystems, climate change can hinder management success by increasing the frequency and intensity of fire and insect outbreaks that cause massive tree die-offs and abrupt habitat change. Resource managers often use ecological indicators to gain insight into the health and status of ecosystems due to the challenge of monitoring all aspects of any ecosystem. Birds are increasingly identified as appropriate taxa for predicting changes in biodiversity and ecological integrity around the globe. We assessed the effects of bark beetle induced forest die-off on patterns of avian diversity in western Montana. We used songbirds, which are ubiquitous and possess attributes capturing the complexity of forests as ecological indicators. In addition to assessing the effects of bark beetle forest die-off on bird diversity we also sought to examine the relative importance of the “conspecific neighborhood” in influencing species-level occurrence rates at a given survey location. This approach is motivated by the idea that individuals of a species aggregate around resources. It follows, that a species is more likely to occur in a patch surrounded by other occupied patches (the conspecific neighborhood). Incorporating measures of spatial autocorrelation in ecological studies is not new. However, this topic is only just beginning to be applied in the context of more recent analytical advances such as Bayesian multi-species hierarchal models used to estimate species abundance and occurrence rates

    Effects of Electric Fence Permeability on Grizzly and Black Bears in the Blackfoot Valley

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    Electric fencing is an effective tool for deterring bears from calving areas and bee yards, however scientific evaluations of the impacts of large-scale electric fencing on bear movements and habitat use are lacking.  In 2015 and 2016, we conducted a study in the Blackfoot Valley to evaluate A) the efficacy of rapid-deployment electric fencing designs in deterring bears from agricultural lands, and B) landscape level space use and permeability of agricultural lands relative to electric fences.  Baited enclosures of 2 fencing configurations were established in the valley.  Each enclosure was systematically energized and unenergized for 3-day periods; passage into the enclosure was monitored with trail cameras to provide information on effectiveness and permeability. In addition, we established 60 randomly selected camera trap stations throughout the valley to evaluate landscape-level use relative to electric fences. Daily locations provided by 4 grizzly bears fitted with GPS collars in 2016 will provide individual-level information on seasonal movements and habitat selection relative to electric fences. The proportion of black bears that were deterred from both configurations of fence when turned on or off over both years was 61% and the proportion that successfully penetrated the enclosures was 38%. The proportion of grizzly bears that were deterred from both configurations of fence over both years was 69% and the proportion that were successful was 30%. The camera traps did not detect enough individuals to conduct a hierarchical occupancy analysis. We will collect the GPS collars in 2017 and conduct an RUF analysis on space use

    Measurement-Based Noiseless Linear Amplification for Quantum Communication

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    Entanglement distillation is an indispensable ingredient in extended quantum communication networks. Distillation protocols are necessarily non-deterministic and require advanced experimental techniques such as noiseless amplification. Recently it was shown that the benefits of noiseless amplification could be extracted by performing a post-selective filtering of the measurement record to improve the performance of quantum key distribution. We apply this protocol to entanglement degraded by transmission loss of up to the equivalent of 100km of optical fibre. We measure an effective entangled resource stronger than that achievable by even a maximally entangled resource passively transmitted through the same channel. We also provide a proof-of-principle demonstration of secret key extraction from an otherwise insecure regime. The measurement-based noiseless linear amplifier offers two advantages over its physical counterpart: ease of implementation and near optimal probability of success. It should provide an effective and versatile tool for a broad class of entanglement-based quantum communication protocols.Comment: 7+3 pages, 5+1 figures, close to published versio

    Effect of statins on venous thromboembolic events: a meta-analysis of published and unpublished evidence from randomised controlled trials

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    Background - It has been suggested that statins substantially reduce the risk of venous thromboembolic events. We sought to test this hypothesis by performing a meta-analysis of both published and unpublished results from randomised trials of statins. Methods and Findings - We searched MEDLINE, EMBASE, and Cochrane CENTRAL up to March 2012 for randomised controlled trials comparing statin with no statin, or comparing high dose versus standard dose statin, with 100 or more randomised participants and at least 6 months' follow-up. Investigators were contacted for unpublished information about venous thromboembolic events during follow-up. Twenty-two trials of statin versus control (105,759 participants) and seven trials of an intensive versus a standard dose statin regimen (40,594 participants) were included. In trials of statin versus control, allocation to statin therapy did not significantly reduce the risk of venous thromboembolic events (465 [0.9%] statin versus 521 [1.0%] control, odds ratio [OR] = 0.89, 95% CI 0.78–1.01, p = 0.08) with no evidence of heterogeneity between effects on deep vein thrombosis (266 versus 311, OR 0.85, 95% CI 0.72–1.01) and effects on pulmonary embolism (205 versus 222, OR 0.92, 95% CI 0.76–1.12). Exclusion of the trial result that provided the motivation for our meta-analysis (JUPITER) had little impact on the findings for venous thromboembolic events (431 [0.9%] versus 461 [1.0%], OR = 0.93 [95% CI 0.82–1.07], p = 0.32 among the other 21 trials). There was no evidence that higher dose statin therapy reduced the risk of venous thromboembolic events compared with standard dose statin therapy (198 [1.0%] versus 202 [1.0%], OR = 0.98, 95% CI 0.80–1.20, p = 0.87). Risk of bias overall was small but a certain degree of effect underestimation due to random error cannot be ruled out. Please see later in the article for the Editors' Summary. Conclusions - The findings from this meta-analysis do not support the previous suggestion of a large protective effect of statins (or higher dose statins) on venous thromboembolic events. However, a more moderate reduction in risk up to about one-fifth cannot be ruled out

    Bessere Verlaufsdokumentation bei Patienten mit lumboradikulÀren Schmerzsyndromen: Der modifizierte NASS-Fragebogen

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    Zusammenfassung: Hintergrund: Zweck dieser Studie war es, ein zuverlĂ€ssiges und einfach anzuwendendes Instrument zur Erfassung des Krankheitsverlaufs und des Therapieerfolgs bei RĂŒckenschmerzpatienten mit lumboradikulĂ€ren Syndromen vorzustellen. Methodik: Es wurden Daten von Patienten, welche sich einer Mikrodiskektomie wegen lumboradikulĂ€rem Syndrom unterzogen, in die Studie eingeschlossen und mittels des 17-teiligen NASS-Fragebogens (North American Spine Society) in Form eines Interviews vor und nach dem operativen therapeutischen Eingriff befragt. Außerdem wurden die demographischen Daten und KomorbiditĂ€ten erhoben. Über die Auswertung der EffektstĂ€rke bzw. Standardized Response Mean konnten die Fragen mit der stĂ€rksten VerĂ€nderung (vorher/nachher) fĂŒr das Behandlungsergebnis ausgewĂ€hlt werden. Ergebnisse: Es konnten die DatensĂ€tze von 139Patienten ausgewertet werden. Aus den 3Dimensionen Schmerz, neurologische Symptome und BeeintrĂ€chtigung im Alltag wurden jeweils diejenigen Fragen mit der höchsten VerĂ€nderung ausgewĂ€hlt (hohe E.S. bzw. S.R.M.). In Abstimmung mit der klinischen Relevanz ergab sich schließlich die Auswahl von 8Fragen als konzentrierte Kurzform des NASS-Fragebogens. Schlussfolgerung: In dem von uns vorgestellten Instrument eines kurzen und aussagekrĂ€ftigen Fragebogens sehen wir eine nĂŒtzliche und in der Klinik einfach einzusetzende Möglichkeit zur verbesserten Dokumentation bei Patienten mit lumboradikulĂ€ren Syndromen, insbesondere auch zur Effektmessung therapeutischer Interventionen im Sinne einer patientenorientierten ErgĂ€nzung der klinischen Befunderhebung und Diagnostik. Dieses neue Instrument könnte helfen, die QualitĂ€tssicherung bei der konservativen und interventionellen Schmerzbehandlung der Patienten mit lumboradikulĂ€ren Schmerzsyndromen zu verbesser

    Evaluating the Potential of Using 5-Azacytidine as an Epimutagen

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    A number of early flowering lines were induced when 5-azacytidine was applied to germinating flax (Linum usitatissimum L.) seed. The genetics of these lines indicate that the induced changes are epigenetic and probably result from demethylation of the genomic DNA at loci that affect flowering age. Although the growth and development of three stable early flowering lines are altered and the percentage of filled seed was reduced in all three lines compared with controls, measures of seed productivity demonstrated that harvest index was unaffected in two of the lines. In the third, harvest index was lower than normal and both seed set per capsule and seed mass per 100 seed were reduced. Furthermore, six generations after induction this line began to display relatively high levels of polyembryony. The late appearance of this twinning and other aspects related to working with lines induced by 5-azacytidine and using 5-azacytidine as an epimutagen are discussed

    Experimental demonstration of Gaussian protocols for one-sided device-independent quantum key distribution

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    Nonlocal correlations, a longstanding foundational topic in quantum information, have recently found application as a resource for cryptographic tasks where not all devices are trusted, for example in settings with a highly secure central hub, such as a bank or government department, and less secure satellite stations which are inherently more vulnerable to hardware "hacking" attacks. The asymmetric phenomena of Einstein-Podolsky-Rosen steering plays a key role in one-sided device-independent quantum key distribution (1sDI-QKD) protocols. In the context of continuous-variable (CV) QKD schemes utilizing Gaussian states and measurements, we identify all protocols that can be 1sDI and their maximum loss tolerance. Surprisingly, this includes a protocol that uses only coherent states. We also establish a direct link between the relevant EPR steering inequality and the secret key rate, further strengthening the relationship between these asymmetric notions of nonlocality and device independence. We experimentally implement both entanglement-based and coherent-state protocols, and measure the correlations necessary for 1sDI key distribution up to an applied loss equivalent to 7.5 km and 3.5 km of optical fiber transmission respectively. We also engage in detailed modelling to understand the limits of our current experiment and the potential for further improvements. The new protocols we uncover apply the cheap and efficient hardware of CVQKD systems in a significantly more secure setting.Comment: Addition of experimental results and (several) new author

    2,2\u27-Dipyrrolidine as a Precursor to Novel Diazatricyclic Systems

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    Reaction of newly available 2,2\u27-dipyrrolidine with a variety of biselectrophiles gave selectively either novel diazatricyclic systems having bridgehead nitrogen atoms or the N,N\u27-disubstituted-2,2\u27-dipyrrolidines in good to excellent yields

    Entanglement properties of a measurement-based entanglement distillation experiment

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    Measures of entanglement can be employed for the analysis of numerous quantum information protocols. Due to computational convenience, logarithmic negativity is often the choice in the case of continuous variable systems. In this work, we analyse a continuous variable measurement-based entanglement distillation experiment using a collection of entanglement measures. This includes: logarithmic negativity, entanglement of formation, distillable entanglement, relative entropy of entanglement, and squashed entanglement. By considering the distilled entanglement as a function of the success probability of the distillation protocol, we show that the logarithmic negativity surpasses the bound on deterministic entanglement distribution at a relatively large probability of success. This is in contrast to the other measures which would only be able to do so at much lower probabilities, hence demonstrating that logarithmic negativity alone is inadequate for assessing the performance of the distillation protocol. In addition to this result, we also observed an increase in the distillable entanglement by making use of upper and lower bounds to estimate this quantity. We thus demonstrate the utility of these theoretical tools in an experimental setting.Comment: 12 pages, 8 figures, submitte

    A gradual process of recombination restriction in the evolutionary history of the sex chromosomes in dioecious plants.

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    To help understand the evolution of suppressed recombination between sex chromosomes, and its consequences for evolution of the sequences of Y-linked genes, we have studied four X-Y gene pairs, including one gene not previously characterized, in plants in a group of closely related dioecious species of Silene which have an X-Y sex-determining system (S. latifolia, S. dioica, and S. diclinis). We used the X-linked copies to build a genetic map of the X chromosomes, with a marker in the pseudoautosomal region (PAR) to orient the map. The map covers a large part of the X chromosomes--at least 50 centimorgans. Except for a recent rearrangement in S. dioica, the gene order is the same in the X chromosomes of all three species. Silent site divergence between the DNA sequences of the X and Y copies of the different genes increases with the genes' distances from the PAR, suggesting progressive restriction of recombination between the X and Y chromosomes. This was confirmed by phylogenetic analyses of the four genes, which also revealed that the least-diverged X-Y pair could have ceased recombining independently in the dioecious species after their split. Analysis of amino acid replacements vs. synonymous changes showed that, with one possible exception, the Y-linked copies appear to be functional in all three species, but there are nevertheless some signs of degenerative processes affecting the genes that have been Y-linked for the longest times. Although the X-Y system evolved quite recently in Silene (less than 10 million years ago) compared to mammals (about 320 million years ago), our results suggest that similar processes have been at work in the evolution of sex chromosomes in plants and mammals, and shed some light on the molecular mechanisms suppressing recombination between X and Y chromosomes
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