2,215 research outputs found
Diversity in the organization of elastin bundles and intramembranous muscles in bat wings
Unlike birds and insects, bats fly with wings composed of thin skin that envelops the bones of the forelimb and spans the area between the limbs, digits, and sometimes the tail. This skin is complex and unusual; it is thinner than typical mammalian skin and contains organized bundles of elastin and embedded skeletal muscles. These elements are likely responsible for controlling the shape of the wing during flight and contributing to the aerodynamic capabilities of bats. We examined the arrangement of two macroscopic architectural elements in bat wings, elastin bundles and wing membrane muscles, to assess the diversity in bat wing skin morphology. We characterized the plagiopatagium and dactylopatagium of 130 species from 17 families of bats using crossāpolarized light imaging. This method revealed structures with distinctive relative birefringence, heterogeneity of birefringence, variation in size, and degree of branching. We used previously published anatomical studies and tissue histology to identify birefringent structures, and we analyzed their architecture across taxa. Elastin bundles, muscles, neurovasculature, and collagenous fibers are present in all species. Elastin bundles are oriented in a predominantly spanwise or proximodistal direction, and there are five characteristic muscle arrays that occur within the plagiopatagium, far more muscle than typically recognized. These results inform recent functional studies of wing membrane architecture, support the functional hypothesis that elastin bundles aid wing folding and unfolding, and further suggest that all bats may use these architectural elements for flight. All species also possess numerous muscles within the wing membrane, but the architecture of muscle arrays within the plagiopatagium varies among families. To facilitate present and future discussion of these muscle arrays, we refine wing membrane muscle nomenclature in a manner that reflects this morphological diversity. The architecture of the constituents of the skin of the wing likely plays a key role in shaping wings during flight
Southwest Pacific Ocean Circulation and Climate Experiment (SPICE) - part I. Scientific background
Science lives: School choices and ānatural tendenciesā
An analysis of 12 semi-structured interviews with university-based scientists and non-scientists illustrates their life journeys towards, or away from, science and the strengths and impact of life occurrences leading them to choose science or non-science professions. We have adopted narrative approaches and used Mezirow's transformative learning theory framework. The areas of discussion from the result have stressed on three main categories that include āsmooth transitionā, āincremental wavering transition' and ātransformative transitionā. The article concludes by discussing the key influences that shaped initial attitudes and direction in these people through natural inclination, environmental inspirations and perceptions of science
Complementarity of Private and Correctable Subsystems in Quantum Cryptography and Error Correction
We make an explicit connection between fundamental notions in quantum
cryptography and quantum error correction. Error-correcting subsystems (and
subspaces) for quantum channels are the key vehicles for contending with noise
in physical implementations of quantum information-processing. Private
subsystems (and subspaces) for quantum channels play a central role in
cryptographic schemes such as quantum secret sharing and private quantum
communication. We show that a subsystem is private for a channel precisely when
it is correctable for a complementary channel. This result is shown to hold
even for approximate notions of private and correctable defined in terms of the
diamond norm for superoperators.Comment: 5 pages, 2 figures, preprint versio
Evaluation of in vitro mucoadhesiveness and texture profile analysis of doxycycline in situ hydrogels
Acknowledgements: This work was supported by a research grant from the University of Iceland (RannsĆ³knarsjĆ³Ć°ur HĆ”skĆ³la Ćslands). Publisher Copyright: Ā© 2020 Govi-Verlag Pharmazeutischer Verlag GmbH. All rights reserved.Delivery of active ingredients to the oral mucosa from topically applied formulations reduces side effects from systemic administration and enhances the treatment efficiency. The challenge however, is to maintain the formulation at the administration site due to rapid salivary flow and mechanical movements of the mouth. Therefore, addition of mucoadhesive polymers could aid in enhancing the formulation residence time by increasing the mucoadhesion capacity but this effect is negligible especially if low ratio of mucoadhesive polymers are added to the formulation. Different mucoadhesive polymers at 0.5% w/w (either single or combination of two polymers) were added to the hydrogels and tested for mucoadhesion capacity, tensile strengths, adhesiveness, cohesiveness, compressibility and hardness. 0.5% povidone showed significantly highest work of mucoadhesion, 0.5% Carbopol formulation showed least cohesiveness and 0.5% HPMC showed highest adhesiveness, but a formulation containing a combination of 0.25% HPMC and 0.25% povidone showed the ideal parameters among all the mucoadhesive polymers tested. The effect of increase in concentration of HPMC (0.5, 1, 1.5, 2%) showed linear relationship for work of mucoadhesion and tensile strengths whereas for TPA the values were non-linear. The drug release from the optimized polymer matrices was found to follow zero-order release profile and the mechanism was found to be super case-II transport relaxation release. The results of this study indicate the mucoadhesive polymers do not impact the tensile strengths (p=0.05), but the texture properties and work of mucoadhesion of the formulations can be significantly (p<0.05) altered by the choice of mucoadhesive component at 0.5%w/w, though not for all the polymers tested. The study provides scope to predict in vivo performance and helps optimize for localized delivery.Peer reviewe
Seismic structure of the southern Gulf of California from Los Cabos block to the East Pacific Rise
Multichannel reflection and coincident wide-angle seismic data collected during the 2002 Premier Experiment, Sea of Cortez, Addressing the Development of Oblique Rifting (PESCADOR) experiment provide the most detailed seismic structure to date of the southern Gulf of California. Multichannel seismic (MCS) data were recorded with a 6-km-long streamer, 480-channel, aboard the R/V Maurice Ewing, and wide-angle data was recorded by 19 instruments spaced every similar to 12 km along the transect. The MCS and wide-angle data reveal the seismic structure across the continent-ocean transition of the rifted margin. Typical continental and oceanic crust are separated by a similar to 75-km-wide zone of extended continental crust dominated by block-faulted basement. Little lateral variation in crustal thicknesses and seismic velocities is observed in the oceanic crust, suggesting a constant rate of magmatic productivity since seafloor spreading began. Oceanic crustal thickness and mean crustal velocities suggest normal mantle temperature (1300 degrees C) and passive mantle upwelling at the early stages of seafloor spreading. The crustal thickness, width of extended continental crust, and predicted temperature conditions all indicate a narrow rift mode of extension. On the basis of upper and lower crust stretching factors, an excess of lower crust was found in the extended continental crust. Total extension along transect 5W is estimated to be similar to 35 km. Following crustal extension, new oceanic crust similar to 6.4-km-thick was formed at a rate of similar to 48 mm a(-1) to accommodate plate separation
Stability and quasi-normal modes of charged black holes in Born-Infeld gravity
In this paper we study the stability and quasi-normal modes of scalar
perturbations of black holes. The static charged black hole considered here is
a solution to Born-Infeld electrodynamics coupled to gravity. We conclude that
the black hole is stable. We also compare the stability of it with its linear
counter-part Reissner-Nordstrom black hole. The quasi-normal modes are computed
using the WKB method. The behavior of these modes with the non-linear
parameter, temperature, mass of the scalar field and the spherical index are
analyzed in detail.Comment: Latex, 17 pages, 13 figures, some sections edited, references adde
Spatiotemporal heterogeneity of water flowpaths controls dissolved organic carbon sourcing in a snow-dominated, headwater catchment
The non-uniform distribution of water in snowdrift-driven systems can lead to spatial heterogeneity in vegetative communities and soil development, as snowdrifts may locally increase weathering. The focus of this study is to understand the coupled hydrological and biogeochemical dynamics in a heterogeneous, snowdrift-dominated headwater catchment (Reynolds Mountain East, Reynolds Creek Critical Zone Observatory, Idaho, USA). We determine the sources and fluxes of stream water and dissolved organic carbon (DOC) at this site, deducing likely flowpaths from hydrometric and hydrochemical signals of soil water, saprolite water, and groundwater measured through the snowmelt period and summer recession. We then interpret flowpaths using end-member mixing analysis in light of inferred subsurface structure derived from electrical resistivity and seismic velocity transects. Streamwater is sourced primarily from groundwater (averaging 25% of annual streamflow), snowmelt (50%), and water traveling along the saprolite/bedrock boundary (25%). The latter is comprised of the prior year\u27s soil water, which accumulates DOC in the soil matrix through the summer before flushing to the saprolite during snowmelt. DOC indices suggest that it is sourced from terrestrial carbon, and derives originally from soil organic carbon (SOC) before flushing to the saprolite/bedrock boundary. Multiple subsurface regions in the catchment appear to contribute differentially to streamflow as the season progresses; sources shift from the saprolite/bedrock interface to deeper bedrock aquifers from the snowmelt period into summer. Unlike most studied catchments, lateral flow of soil water during the study year is not a primary source of streamflow. Instead, saprolite and groundwater act as integrators of soil water that flows vertically in this system. Our results do not support the flushing hypothesis as observed in similar systems and instead indicate that temporal variation in connectivity may cause the unexpected dilution behavior displayed by DOC in this catchment
Approximal Caries Detection by DIFOTI: In Vitro
The aim of the present study was to compare the diagnostic accuracy/efficacy of digital imaging fiber-optic transillumination (DIFOTI) with film and digital radiography, in detection of approximal caries lesions. One hundred and twelve approximal surfaces were scored for caries, using DIFOTI images film and digital radiographs. All three sets of images were examined twice by 8 observers, with a minimal interval of one week between examinations. Validation of histological sections served as a reference standard. Reproducibility, based on intra- and interobserver agreement, was similar for all three methods. At diagnostic threshold D1 (enamel and dentin caries), DIFOTI showed significantly higher sensitivity, but differences in specificity between methods were nonsignificant. Diagnostic accuracy in the form of area under the receiver operating characteristic curve (AUC) was significantly higher for DIFOTI. At diagnostic threshold D3 (dentin caries), the differences in sensitivity and AUC among methods were nonsignificant, but DIFOTI showed significantly lower specificity. Compared with the radiographs, DIFOTI showed closer agreement, expressed as weighted kappa values, with the reference standard. The results show that under in vitro conditions, the diagnostic accuracy of DIFOTI in detecting early approximal enamel lesions is greater than that of film and digital radiography, while the potential for detecting lesions in dentin is similar for all three methods
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The chaperone protein HSP47: a platelet collagen binding protein that contributes to thrombosis and haemostasis
Objective: Heat shock protein 47 (HSP47) is an intracellular chaperone protein that is vital for collagen biosynthesis in collagen secreting cells. This protein has also been shown to be present on the surface of platelets. Given the importance of collagen and its interactions with platelets in triggering haemostasis and thrombosis, in this study we sought to characterise the role of HSP47 on these cells.
Approach and Results: The deletion of HSP47 in mouse platelets or its inhibition in human platelets reduced their function in response to collagen and the GPVI agonist (CRP-XL), but responses to thrombin were unaltered. In the absence of functional HSP47, the interaction of collagen with platelets was reduced, and this was associated with reduced GPVI-collagen binding, signalling and platelet activation. Thrombus formation on collagen, under arterial flow conditions was also decreased following the inhibition or deletion of HSP47, in the presence or absence of the eptifibatide, consistent with a role for HSP47 in enhancing platelet adhesion to collagen. Platelet adhesion under flow to von Willebrand Factor was unaltered following HSP47 inhibition. Laser-induced thrombosis in cremaster muscle arterioles was reduced and bleeding time was prolonged in HSP47 deficient mice or following inhibition of HSP47.
Conclusions: Our study demonstrates the presence of HSP47 on the platelet surface where it interacts with collagen, stabilises platelet adhesion and increases collagen mediated signalling and therefore thrombus formation and haemostasis
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