454 research outputs found

    Thermal Biology and immersion tolerance of the Beringian pseudoscorpion Wyochernes 4 asiaticus

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    Wyochernes asiaticus (Arachnida: Pseudoscorpiones: Chernetidae) is a pseudoscorpion distributed across Beringia, the areas of Yukon, Alaska and Siberia that remained unglaciated at the last glacial maximum. Along with low temperatures, its streamside habitat suggests that submergence during flood events is an important physiological challenge for this species. We collected W. asiaticus in midsummer from 66.8N Yukon Territory, Canada, and measured thermal and immersion tolerance. Wyochernes asiaticus is freeze-avoidant, with a mean supercooling point of -6.9 C. It remains active at low temperatures (mean critical thermal minimum, CTmin, is -3.6 C) and has a critical thermal maximum (CTmax) of 37.8 C, which is lower than other arachnids and consistent with its restriction to high latitudes. Fifty per cent of W. asiaticus individuals survived immersion in oxygen-depleted water for 17 days, suggesting that this species has high tolerance to immersion during flooding events. To our knowledge, these are the first data on the environmental physiology of any pseudoscorpion and a new addition to our understanding of the biology of polar microarthropods

    3-D kinematic comparison of treadmill and overground running.

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    Studies investigating the mechanics of human movement are often conducted using the treadmill. The treadmill is an attractive device for the analysis of human locomotion. Studies comparing overground and treadmill running have analyzed discrete variables, however differences in excursion from footstrike to peak angle and range of motion during stance have yet to be examined. This study aimed to examine the 3-D kinematics of the lower extremities during overground and treadmill locomotion to determine the extent to which the two modalities differ. Twelve participants ran at 4.0m/s in both treadmill and overground conditions. 3-D angular kinematic parameters during the stance phase were collected using an eight camera motion analysis system. Hip, knee and ankle joint kinematics were quantified in the sagittal, coronal and transverse planes, then compared using paired t-tests. Of the parameters analyzed hip flexion at footstrike 12° hip range of motion 17°, peak hip flexion 12.7°, hip transverse plane range of motion 8° peak knee flexion 5° and peak ankle excursion range 6.6°, coronal plane ankle angle at toe-off 6.5° and peak ankle eversion 6.3° were found to be significantly different. These results lead to the conclusion that the mechanics of treadmill locomotion cannot be generalized to overground

    The Partition Function of Multicomponent Log-Gases

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    We give an expression for the partition function of a one-dimensional log-gas comprised of particles of (possibly) different integer charge at inverse temperature {\beta} = 1 (restricted to the line in the presence of a neutralizing field) in terms of the Berezin integral of an associated non- homogeneous alternating tensor. This is the analog of the de Bruijn integral identities [3] (for {\beta} = 1 and {\beta} = 4) ensembles extended to multicomponent ensembles.Comment: 14 page

    Thermal limits of summer-collected Pardosa wolf spiders (Araneae: Lycosidae) from the Yukon Territory and Greenland

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    Arctic and sub-Arctic terrestrial ectotherms contend with large daily and seasonal temperature ranges. However, there are few data available on the thermal biology of these high-latitude species, especially arachnids. We determined the lower and upper thermal limits of seven species of wolf spider from the genus Pardosa (Araneae: Lycosidae) collected in summer from the Yukon Territory (Canada) and Southern Greenland. None of these species survived freezing, and while spiderlings appeared freeze-avoidant, surviving to their supercooling point (SCP, the temperature at which they spontaneously freeze), chill-susceptible adults and juveniles died at temperatures above their SCP. The critical thermal minimum (CTmin, the lower temperature of activity) and SCP were very close (spiders continued moving until they freeze), and at − 5.4 to − 8.4 °C, are not substantially lower than those of lower-latitude species. The SCP of spiderlings was significantly lower than that of overwintering juveniles or adults, likely because of their small size. There was no systematic variation in SCP among collection sites, latitude, or species. Critical thermal maxima (CTmax) ranged from + 42.3 to + 46.8 °C, showed no systematic patterns of variation, and were also similar to those of lower-latitude relatives. Overall, heat tolerances of the Pardosa spp. were likely sufficient to tolerate even very warm Arctic summer temperatures, but cold tolerance is probably inadequate to survive winter conditions. We expect that seasonal thermal plasticity is necessary for overwintering in these species

    Distributing Data and Analysis Software Containers For Better Data Sharing in Clinical Research

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    Introduction: Data sharing in clinical research is critical for increasing knowledge discovery. Data and software tools should be FAIR: Findable, Accessible, Inter-operable and Re-usable. Many bottlenecks exist in the process of a clinical investigator using shared data including data acquisition and statistical analysis. The objective of this project is to develop a structure for sharing data and providing rapid automated statistical analysis through creation of a pre-packaged, open-source software container. Methods: We use the open source software container technologies VirtualBox and Vagrant to create a template for sharing clinical data and analysis scripts as a single container. We use a timer to record the time necessary to setup and initialize the software container and view the results. Results: We have created a template for sharing data and analysis scripts together using open source software container technologies VirtualBox and Vagrant. We found the time needed to initialize the container to be 5 minutes and 36 seconds for a macOS-based machine and 7 minutes and 2 seconds for a Windows-based machine. Containers can be downloaded and executed from any Mac or Windows computer allowing both the reuse of and interaction with the data. This greatly reduces the time and effort needed to obtain and analyze clinical data. Conclusion: Reducing the time and effort needed to obtain and analyze clinical data increases the time available for data exploration and the discovery of new knowledge. This can be effectively achieved using software containers and virtualization

    The influence of barefoot and barefoot inspired footwear on the kinetics and kinematics of running in comparison to conventional running shoes.

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    Barefoot running has experienced a resurgence in footwear biomechanics literature, based on the supposition that it serves to reduce the occurrence of overuse injuries in comparison to conventional shoe models. This consensus has lead footwear manufacturers to develop shoes which aim to mimic the mechanics of barefoot locomotion. This study compared the impact kinetics and 3-D joint angular kinematics observed whilst running: barefoot, in conventional cushioned running shoes and in shoes designed to integrate the perceived benefits of barefoot locomotion. The aim of the current investigation was therefore to determine whether differences in impact kinetics exist between the footwear conditions and whether shoes which aim to simulate barefoot movement patterns can closely mimic the 3-D kinematics of barefoot running. Twelve participants ran at 4.0 m.s-1±5% in each footwear condition. Angular joint kinematics from the hip, knee and ankle in the sagittal, coronal and transverse planes were measured using an eight camera motion analysis system. In addition simultaneous tibial acceleration and ground reaction forces were obtained. Impact parameters and joint kinematics were subsequently compared using repeated measures ANOVAs. The kinematic analysis indicates that in comparison to the conventional and barefoot inspired shoes that running barefoot was associated significantly greater plantar-flexion at footstrike and range of motion to peak dorsiflexion. Furthermore, the kinetic analysis revealed that compared to the conventional footwear impact parameters were significantly greater in the barefoot condition. Therefore this study suggests that barefoot running is associated with impact kinetics linked to an increased risk of overuse injury, when compared to conventional shod running. Furthermore, the mechanics of the shoes which aim to simulate barefoot movement patterns do not appear to closely mimic the kinematics of barefoot locomotion

    Cellular Models of Aggregation-Dependent Template-Directed Proteolysis to Characterize Tau Aggregation Inhibitors for Treatment of Alzheimer's Disease

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    Copyright © 2015, The American Society for Biochemistry and Molecular Biology. Acknowledgements-We thank Drs Timo Rager and Rolf Hilfiker (Solvias, Switzerland) for polymorph analyses.Peer reviewedPublisher PD

    Correlation Functions for \beta=1 Ensembles of Matrices of Odd Size

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    Using the method of Tracy and Widom we rederive the correlation functions for \beta=1 Hermitian and real asymmetric ensembles of N x N matrices with N odd.Comment: 15 page

    Random-matrix theory of amplifying and absorbing resonators with PT or PTT' symmetry

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    We formulate gaussian and circular random-matrix models representing a coupled system consisting of an absorbing and an amplifying resonator, which are mutually related by a generalized time-reversal symmetry. Motivated by optical realizations of such systems we consider a PT or a PTT' time-reversal symmetry, which impose different constraints on magneto-optical effects, and then focus on five common settings. For each of these, we determine the eigenvalue distribution in the complex plane in the short-wavelength limit, which reveals that the fraction of real eigenvalues among all eigenvalues in the spectrum vanishes if all classical scales are kept fixed. Numerically, we find that the transition from real to complex eigenvalues in the various ensembles display a different dependence on the coupling strength between the two resonators. These differences can be linked to the level spacing statistics in the hermitian limit of the considered models.Comment: 19 pages, 9 figure
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