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Infiltration of monocyte-derived cells to sites of infection and injury is greater in males than in females, due in part, to increased chemotaxis, the process of directed cell movement toward a chemical signal. The mechanisms governing sexual dimorphism in chemotaxis are not known. We hypothesized a role for the store-operated calcium entry (SOCE) pathway in regulating chemotaxis by modulating leading and trailing edge membrane dynamics. We measured the chemotactic response of bone marrow-derived macrophages migrating toward complement component 5a (C5a). Chemotactic ability was dependent on sex and inflammatory phenotype (M0, M1, and M2), and correlated with SOCE. Notably, females exhibited a significantly lower magnitude of SOCE than males. When we knocked out the SOCE gene, stromal interaction molecule 1 (STIM1), it eliminated SOCE and equalized chemotaxis across both sexes. Analysis of membrane dynamics at the leading and trailing edges showed that STIM1 influences chemotaxis by facilitating retraction of the trailing edge. Using BTP2 to pharmacologically inhibit SOCE mirrored the effects of STIM1 knockout, demonstrating a central role of STIM/Oraimediated calcium signaling. Importantly, by monitoring the recruitment of adoptively transferred monocytes in an in vivo model of peritonitis, we show that increased infiltration of male monocytes during infection is dependent on STIM1. These data support a model in which STIM1-dependent SOCE is necessary and sufficient for mediating the sex difference in monocyte recruitment and macrophage chemotactic ability by regulating trailing edge dynamics. [ABSTRACT FROM AUTHOR]

Severe levels of acidosis (pH < 6.8) have been shown to cause a sustained rise in cytosolic Ca2+ concentration in carotid body Type 1 (glomus) cells. To understand how physiologically relevant levels of acidosis regulate Ca2+ signaling in glomus cells, we studied the effects of small changes in extracellular pH (pHo) on the kinetics of Ca2+ oscillations. A decrease in pHo from 7.4 to 7.3 (designated mild) and 7.2 (designated moderate) acidosis produced significant increases in the frequency and amplitude of Ca2+ oscillations. These effects of acidosis on Ca2+ oscillations were not blocked by NS383 and amiloride [acid-sensing ion channel (ASIC) inhibitors]. Mild and moderate levels of acidosis, however, caused a small but significant inhibition of two-pore domain acid-sensing K+ channels (TASK) (TASK-1- and TASK-3-like channels) and depolarized the cell by 6-13 mV. Acidosis-induced increase in Ca2+ oscillations was inhibited by nifedipine (1 µM; L-type Cav inhibitor) and by TTA-P2 (20 µM; T-type Cav inhibitor). Mild inhibition of TASK activity by N-[(2,4-difluorophenyl)methyl]-20-[[[2-(4methoxyphenyl)acetyl]amino]methyl][1,10-biphenyl]-2-carboxamide (A1899) (0.3 mM) and 1-[1-[6-[[1,10-biphenyl]-4-ylcarbonyl)-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine-4-yl]-4-piperidinyl]-1-butanon (PK-THPP) (0.1 µM) increased Ca2+ oscillation frequency to levels similar to those observed with mild-moderate acidosis. Mild acidosis (pHo 7.3) and mild hypoxia (~5%O2) produced similar levels of changes in the kinetics of Ca2+ oscillations. Block of tetraethylammonium (TEA)-sensitive Kv channels did not affect acid-induced increase in Ca2+ oscillations. Our study shows that mild and moderate levels of acidosis increase the frequency and amplitude of Ca2+ oscillations primarily by inhibition of TASK without involving ASICs, and suggests a major role of TASK for signal transduction in response to a physiological change in pHo. [ABSTRACT FROM AUTHOR]

In this study, a 33 full factorial design methodology was used to analyze the effects of spray parameters on the thickness, hardness, and surface porosity of low-pressure cold-sprayed WC-17Ni coatings. Three levels were selected for the spray parameters included in the design which were the powder feed rate (17.1 g/min, 21.1 g/min, and 23.7 g/min), gas temperature (475°C, 500°C, and 525°C), and the nozzle to substrate stand-off distance (3 mm, 5 mm, and 10 mm). It was found that the feed rate was the most significant parameter that affected the coating thickness. The surface porosity was most significantly affected by stand-off distance. The coating hardness was most influenced by the interaction between the feed rate and stand-off distance. An optimization study was then performed to maximize the coating thickness and hardness while minimizing the surface porosity. The optimal spray parameters (OSP) were found to be at a feed rate of 23.7 g/min, 500°C for the carrier gas temperature, and 10 mm for the stand-off distance. The OSP yielded a coating that was 1.22 ± 0.06 mm thick, with a hardness of 364.5 ± 8.5 HV and porosity of 6.8 ± 0.6%. With a multi-parameter process, the system response is affected by both the variation in the individual parameters and the interaction of the parameters with each other. It was also concluded that the interaction between the parameters significantly affected the coating hardness. These results suggest that variation of the selected parameters produce statistically significant effects on the coating quality of WC-17Ni coatings using a low-pressure cold spray system. [ABSTRACT FROM AUTHOR]

Current rates of habitat degradation and climate change are causing unprecedented declines in global biodiversity. Studies on vertebrates highlight how conservation genomics can be effective in identifying and managing threatened populations, but it is unclear how vertebrate‐derived metrics of genomic erosion translate to invertebrates, with their markedly different population sizes and life histories. The Black‐veined White butterfly (Aporia crataegi) was extirpated from Britain in the 1920s. Here, we sequenced historical DNA from 17 specimens collected between 1854 and 1924 to reconstruct demography and compare levels of genomic erosion between extirpated British and extant European mainland populations. We contrast these results using modern samples of the Common Blue butterfly (Polyommatus icarus); a species with relatively stable demographic trends in Great Britain. We provide evidence for bottlenecks in both these species around the period of post‐glacial colonization of the British Isles. Our results reveal different demographic histories and Ne for both species, consistent with their fates in Britain, likely driven by differences in life history, ecology and genome size. Despite a difference, by an order of magnitude, in historical effective population sizes (Ne), reduction in genome‐wide heterozygosity in A. crataegi was comparable to that in P. icarus. Symptomatic of A. crataegi's disappearance were marked increases in runs‐of‐homozygosity (RoH), potentially indicative of recent inbreeding, and accumulation of putatively mildly and weakly deleterious variants. Our results provide a rare glimpse of genomic erosion in a regionally extinct insect and support the potential use of genomic erosion metrics in identifying invertebrate populations or species in decline. [ABSTRACT FROM AUTHOR]

Mesh size dependency caused by strain localization is an ongoing problem in numerical simulations using the finite element method. In order to solve this problem, the concept of including the characteristic element length for regularization is used in the literature. The estimation of the characteristic element length is not a straightforward task since normally the characteristic element length differs from one element to another in the simulation and depends not only on element geometry but also on fracture plane orientation and material orientation. In this paper, an innovative method is proposed to estimate the characteristic element length which works on the orthogonal projection of elements on the fracture plane. The method is implemented in Abaqus/Explicit finite element solver and is verified using simple and more complex load cases such as tensile specimens, open hole specimens, and low-velocity impact. A good correlation between the numerical and experimental results in all of the studied cases was achieved and the proposed method proved to be effective in reducing mesh sensitivity. The use of the volumetric method from the literature for the simulation of open-hole tensile specimens led to more than 25% increase in the estimation of specimen strength while similar values of strength for different element aspect ratios were achieved with the proposed method. [ABSTRACT FROM AUTHOR]

Abstract: Interannual changes in global climate and weather disturbances may influence reproduction in tropical forests. Phenomena such as the El Niño Southern Oscillation (ENSO) are known to produce interannual variation in reproduction, as do severe storms such as hurricanes. Using stationary trap‐based phenology data collected fortnightly from 1993 to 2014 from a hurricane‐affected (1989 Hugo, 1998 Georges) subtropical wet forest in northeastern Puerto Rico, we conducted a time series analysis of flowering and seed production. We addressed (1) the degree to which interannual variation in flower and seed production was influenced by global climate drivers and time since hurricane disturbance, and (2) how long‐term trends in reproduction varied with plant lifeform. The seasonally de‐trended number of species in flower fluctuated over time while the number of species producing seed exhibited a declining trend, one that was particularly evident during the second half of the study period. Lagged El Niño indices and time series hurricane disturbance jointly influenced the trends in numbers of flowering and fruiting species, suggesting complex global influences on tropical forest reproduction with variable periodicities. Lag times affecting flowering tended to be longer than those affecting fruiting. Long‐term patterns of reproduction in individual lifeforms paralleled the community‐wide patterns, with most groups of lifeform exhibiting a long‐term decline in seed but not flower production. Exceptions were found for hemiepiphytes, small trees, and lianas whose seed reproduction increased and then declined over time. There was no long‐term increase in flower production as reported in other Neotropical sites. [ABSTRACT FROM AUTHOR]

Cystathionine-γ-lyase (CSE) is a multifunctional enzyme, and hydrogen sulfide (H 2 S) is one of its products. CSE and H 2 S have recently been proposed to be critical signaling molecules in hypoxia-induced excitation of carotid body (CB) glomus cells and the chemosensory response. Because the role of H 2 S in arterial chemoreception is still debated, we further examined the role of CSE by studying the effects of hypoxia on TASK K + channel activity, cell depolarization, [Ca 2+ ] i and ventilation using CSE +/+ and CSE −/− mice. As predicted, hypoxia reduced TASK activity and depolarized glomus cells isolated from CSE +/+ mice. These effects of hypoxia were not significantly altered in glomus cells from CSE −/− mice. Basal [Ca 2+ ] i and hypoxia-induced elevation of [Ca 2+ ] were also not significantly different in glomus cells from CSE +/+ and CSE −/− mice. In whole-body plethysmography, hypoxia (10%O 2 ) increased minute ventilation in both CSE +/+ and CSE −/− mice equally well, and no significant differences were found in either males or females when adjusted by body weight. Together, these results show that deletion of the CSE gene has no effects on hypoxia-induced changes in TASK, cell depolarization, [Ca 2+ ] i and ventilation, and therefore do not support the idea that CSE/H 2 S signaling is important for CB chemoreceptor activity in mice. [ABSTRACT FROM AUTHOR]

This research article investigated the stress-state and strain-rate-dependent mechanical properties and failure of alumina ceramic. Compression–shear testing was carried out using a split-Hopkinson pressure bar under equivalent strain rates ranging from 1 0 1 s−1 to 1 0 3 s−1. Ultra-high-speed images coupled with digital image correlation were used to investigate the in situ time-evolving strain field and the failure process (e.g., crack growth). Experimental results showed equivalent strength reduced from 4.27 ± 0.23 GPa for the uniaxial compression tests to 3.75 GPa and 2.00 GPa for compression–shear tests across the strain rates and shear angles (5 ° to 25 °), with the strength decreasing with an increasing shear angle. The crack speed ranged from 908 m/s to 3208 m/s across the range of strain rates and shear angles, with a positive correlation noted for crack speeds with strain rate and increasing sensitivity with an increasing shear angle. The extent of localization of shear strain in alumina under compression–shear deformation was observed to be strain-rate-dependent, and it increased with an increasing strain rate of deformation. Furthermore, axial and shear strain localization increased with the increasing shear angle, contributing to local shear failure before the complete failure of the specimen. Overall, this paper provides new insights and measurements of the strain-rate-dependent and shear-dependent strength and crack speeds of alumina under compression–shear loading, and these serve as vital inputs for future computational model development and validation. [ABSTRACT FROM AUTHOR]

Ten distinctive new species of the taxonomically difficult braconine wasp genusGammabraconQuicke, 1984 are described:G. apicoluteussp. nov. from Malaysia (Negri);G. curticornissp. nov. from Malaysia (Negri);G. philippinensissp. nov. from the Philippines;G. siamensissp. nov. from Thailand;G. striatussp. nov. from West Malaysia;G. strandorumsp. nov. from Indonesia (Java),G. subvenasp. nov. from Malaysia (Negri and Sabah);G. townesorumsp. nov. from the Philippines;G. variipennissp. nov. from Thailand; andG. wegenerisp. nov. from Indonesia.Myosoma forticarinataCameron, 1902 is transferred toGammabracon, henceGammabracon forticarinatacomb. nov. A lectotype is designated forGammabracon erythroura(Cameron). The status ofCratobracon strandiellus(Cameron) is discussed and a new combination proposed,Shelfordia strandiellusCameron, 1910 comb. nov. (=Bracon strandiellusCameron). Paucity of discrete morphological variation makes separation of most of the species with orange-red mesosoma, black metasoma and conspicuous back setae currently unrealistic and it may be that there is a single widespread and morphologically variable species. http://zoobank.org/urn:lsid:zoobank.org:pub:56B8884E-99C8-4B53-9747-D011F552312D [ABSTRACT FROM PUBLISHER]

In this paper, the impact-induced fragmentation of a commercially available hot-pressed boron carbide is explored. Fragmentation has been noted previously by many authors to be important in the impact performance of advanced ceramics, and so this paper seeks to provide some of the first near-complete and detailed measurements of individual fragment size and shape distributions available in the literature. Fragment size and shapes are quantified using methods developed in previous papers by the authors, and results reveal that two distinct fragmentation mechanisms exist as a consequence of the impact failure of boron carbide: one mechanism that creates small fragments that is associated with the coalescence of fractures originating from carbonaceous defects in the material, and one that creates larger fragments that is associated with structural failure (e.g., radial and circumferential cracking). While these mechanisms are similar to those noted for uniaxial compressive failure, results presented here highlight the importance of fragment shape as a consequence of impact failure. Namely, results indicate that both blocky and shard fragments are formed during impact into a boron carbide plate. Blocky and shard fragment types span across both the small and large fragmentation mechanisms. Using Scanning Electron Microscopy, blocky fragments were found to be associated with the predominant growth of cracks parallel to the impact direction, while shard fragments contain fracture surfaces that are associated with crack growth and coalescence in a direction perpendicular to the impact direction. The shards are, thus, believed to be a consequence of structural bending. No amorphous features were found on any blocky or shard fragments observed in this study (determined using Raman Spectroscopy), suggesting brittle fracture may be the dominant mechanisms that creates the shard fragments. Altogether, the implications of these results is that one can control fragment size and shape by controlling the carbonaceous defects population in boron carbide. This should help in the design of next-generation advanced ceramics for personal protection. [ABSTRACT FROM AUTHOR]

A recent study showed that hypoxia activates a Ca 2+ -sensitive, Na + -permeable non-selective cation channel (NSC) in carotid body glomus cells. We studied the effects of mitochondrial inhibitors that increase Ca 2+ influx via Ca 2+ channel (Ca v ), and receptor agonists that release Ca 2+ from endoplasmic reticulum (ER) on NSC. Mitochondrial inhibitors (NaCN, FCCP, H 2 S, NO) elevated [Ca 2+ ] i and activated NSC. Angiotensin II and acetylcholine that elevate [Ca 2+ ] i via the Gq-IP 3 pathway activated NSC. However, endothelin-1 (Gq) and 5-HT (Gq) showed little or no effect on [Ca 2+ ] i and did not activate NSC. Adenosine (Gs) caused a weak rise in [Ca 2+ ] i but did not activate NSC. Dopamine (Gs) and γ-aminobytyric acid (Gi) were ineffective in raising [Ca 2+ ] i and failed to activate NSC. Store-operated Ca 2+ entry (SOCE) produced by depletion of Ca 2+ stores with cyclopiazonic acid activated NSC. Our results show that Ca 2+ entry via Ca v , ER Ca 2+ release and SOCE can activate NSC. Thus, NSC contributes to both voltage- and receptor-mediated excitation of glomus cells. [ABSTRACT FROM AUTHOR]

Effects of microstructure and material properties on the mechanical behavior of hot-pressed boron carbide are presented. The microstructure and intrinsic microstructural inhomogeneities have been characterized using scanning electron microscopy characterization techniques (SEM/EDS/EBSD). In situ mechanical characterizations of the boron carbide microstructure and its larger inhomogeneities have been performed by nanoindentation. Macroscopic dynamic and quasi-static compressive responses have been studied in two characteristic orientations (parallel and perpendicular to the hot-pressing direction) using a modified compression Kolsky bar setup (strain rates of [ABSTRACT FROM AUTHOR]

Environmental heterogeneity influences the species composition of tropical forests, with implications for patterns of diversity and species coexistence in these hyperdiverse communities. Many studies have examined how variability in soil nutrients and topography influence plant community composition, with differing results. None have quantified the relative contribution of environmental heterogeneity versus endogenous processes to variability in forest community composition over time and with respect to successional recovery., Using five consecutive trees censuses of a forest plot in Puerto Rico, conducted between 1990 and 2011, we evaluated the influence of edaphic and topographic variability on community composition. The plot has a well-documented land-use history and is subject to periodic hurricane disturbance. Using multiple canonical distance-based redundancy analyses, we studied how spatial heterogeneity in soil nutrients and topography structure community composition over time, as the forest recovers from long-term land-use effects and two major hurricanes in 1989 and 1998., For the entire plot, spatial variables (principle coordinates of neighbourhood matrices), representing the autocorrelation of tree species in the community, explained the majority (49-57%) of the variability in tree community composition. The explanatory power of spatial variables decreased over time, as forest structure recovered from hurricane damage and the stems in the understorey died. Soil nutrients and topography, collectively, explained a moderate portion (33-37%) of the species compositional variation and were slightly more robust in explaining compositional differences in areas of more intense past land use., Areas of less-intense past land use showed weaker community-environmental trends overall, illustrating a tendency for stronger resource competition (i.e. light, water and soil nutrients) between species in these areas. This illustrates how environmental-plant community interactions are strengthened by the lasting effects of human land-use legacies, which persist for decades to centuries., Synthesis. Our findings confirm past land use to be a fundamental driver of the structure and composition of secondary forests through its impacts on the tree community, the abiotic terrestrial environment and their interaction. Since the extent of second-growth tropical forests continues to increase, our findings highlight the importance of understanding the processes that determine the rate and nature of their succession. [ABSTRACT FROM AUTHOR]

In the present study, ejecta dynamics techniques are used to investigate the ballistic response of shear thickening particle suspensions as a means of assessing the particle hardness and the role of interparticle friction during penetration. Through particle material variations, the role of particle material strength is discussed primarily through the ratio of the total lateral to total axial kinetic energy of the ejecta field at increasing impact velocities. Two dominant trends are observed in the relation between this ratio of kinetic energy and impact velocity, which are attributed to the properties of the suspended particles. A qualitative model of particle fracture and deformation is proposed to account for the experimental observations. The results of analytical particle strain estimates and computational discrete element modelling of impact ejecta are used to inform the model and discuss the role of interparticle friction in the ejecta field. [ABSTRACT FROM AUTHOR]

Dynamic brittle fragmentation is typically described using analytical and computational approaches for tensile stress-states. However, most fragmentation applications (e.g., impact, blast) involve very large initial compressive stresses and deformations. In this study, the compressive fragmentation of brittle materials is investigated experimentally across a range of materials: silicon carbide, boron carbide, spinel, basalt and a stony meteorite. Analysis of our experimental results suggests that there exists two different regimes in the fragment size distributions, based on two brittle fragmentation mechanisms. The first is a mechanism that produces larger fragments and is associated with the structural failure of the sample being tested. This mechanism is influenced by the loading conditions (rate, stress state) and sample geometry. The second fragmentation mechanism produces comparatively smaller fragments and arises from the coalescence of fractures initiating and coalescence between defects in regions of large stresses and contact forces (e.g., between two fractured surfaces from the larger fragments). A framework is developed for comparing experimental compressive fragmentation results with tensile fragmentation theories. The compressive experimental results are shown to be adequately described by the theories using the new framework. [ABSTRACT FROM AUTHOR]

This study investigates the effects of the processing-induced defect population on the dynamic compressive strength and failure of a hot-pressed boron carbide. Quantitative microscopic analysis was used to determine the distributions of three types of processing-induced inhomogeneities: aluminum nitride, small graphitic particles and pores, and larger graphitic disks. Scanning electron microscopy of fracture surfaces identifies the graphitic disks as fracture initiation sites. The size, orientation and number density of the graphitic disks are then quantified using image processing techniques. We use these defect statistics, in conjunction with recent scaling models, to explore our experimentally measured dynamic compressive strength results. [ABSTRACT FROM AUTHOR]

Knowledge of the relationships between microstructure, stress-state and failure mechanisms is important in the development and validation of numerical models simulating large-scale impact events. In this study, we investigate the effects of microstructural constituent phases and defects on the compressive and tensile strength, failure, and fragmentation of a stony meteorite (GRO 85209). In the first part of the paper we consider the effect of defects on the strength and failure. Strengths are measured and linked with detailed quantification of the important defects in this material. We use the defect statistic measurements in conjunction with our current understanding of rate-dependent strengths to discuss the uniaxial compressive strength measurements of this ordinary chondrite with those of another ordinary chondrite, with a different defect population. In the second part of the paper, we consider the effects of the microstructure and defects on the fragmentation of GRO 85209. Fragment size distributions are measured using image processing techniques and fragments were found to result from two distinct fragmentation mechanisms. The first is a mechanism that is associated with relatively smaller fragments arising from individual defect grains and the coalescence of fractures initiating from microstructure defects. This mechanism becomes more dominant as the strain-rate is increased. The second mechanism is associated with larger fragments that are polyphase and polygrain in character and is dependent on the structural failure mechanisms that are activated during load. In turn, these are dependent on (for example) the strain-rate, stress state, and specimen geometry. The implications of these results are briefly discussed in terms of regolith generation and catastrophic disruption. [ABSTRACT FROM AUTHOR]

Although a number of cytoskeletal derangements have been described in the setting of traumatic axonal injury (TAI), little is known of early structural changes that may serve to initiate a cascade of further axonal degeneration. Recent work by the authors has examined conformational changes in cytoskeletal constituents of neuronal axons undergoing traumatic axonal injury (TAI) following focal compression through confocal imaging data taken in vitro and in situ. The present study uses electron microscopy to understand and quantify in vitro alterations in the ultrastructural composition of microtubules and neurofilaments within neuronal axons of rats following focal compression. Standard transmission electron microscopy processing methods are used to identify microtubules, while neurofilament identification is performed using antibody labeling through gold nanoparticles. The number, density, and spacing of microtubules and neurofilaments are quantified for specimens in sham Control and Crushed groups with fixation at <1min following load. Our results indicate that the axon caliber dependency known to exist for microtubule and neurofilament metrics extends to axons undergoing TAI, with the exception of neurofilament spacing, which appears to remain constant across all Crushed axon diameters. Confidence interval comparisons between Control and Crushed cytoskeletal measures suggests early changes in the neurofilament spatial distributions within axons undergoing TAI may precede microtubule changes in response to applied loads. This may serve as a trigger for further secondary damage to the axon, representing a key insight into the temporal aspects of cytoskeletal degeneration at the component level, and suggests the rapid removal of neurofilament sidearms as one possible mechanism. [ABSTRACT FROM AUTHOR]

We investigate the rate-dependent compressive failure and fragmentation of a hot-pressed boron carbide, under both uniaxial and confined biaxial compression, using quantitative fragment analysis coupled with quantitative microstructural analysis. Two distinct fragmentation regimes are observed, one of which appears to be more sensitive to the microstructural length scales in the material, while the second is more sensitive to the structural character and boundary conditions of the compressed sample. The first regime, which we refer to as "microstructuredependent," appears to be associated with smaller fragments arising from the coalescence of fractures initiating from graphitic inclusions. This regime appears to become more dominant as the strain rate is increased and as the stress-state becomes more confined. The second regime generates larger fragments with the resulting fragment size distribution dependent on the specific structural mechanisms that are activated during macroscopic failure (e.g., buckling of local columns developed during the compression). The average fragment size in the latter regime appears to be reasonably predicted by current fragmentation models. This improved understanding of the effects of microstructure and confinement on fragmentation then provides new insights into prior ballistic studies involving boron carbide. [ABSTRACT FROM AUTHOR]

Modeling of catastrophic disruption requires understanding the processes of dynamic failure and fragmentation. This paper summarizes current mechanisms and models for dynamic failure, strength, and fragmentation, reviewing these from a mechanics perspective and with an emphasis on making links to the developing advances in these areas in the engineering and computational mechanics communities. We describe dynamic failure processes, examine size and rate effects, articulate the scaling concepts that arise naturally from these processes, and examine the influences of these processes on effective strength and fragmentation. [ABSTRACT FROM AUTHOR]

The goal of this study was to determine the molecular identity of a small-conductance (~5-pS) background K channel expressed in trigeminal ganglion (TG) neurons. We tested the hypothesis that the 5-pS channel is a K channel by comparing the pharmacological and single-channel properties of THIK-1 expressed in HEK293 cells. As reported earlier, whole-cell THIK-1 current was inhibited by halothane and activated by arachidonic acid. Among 25 additional modulators tested, bupivacaine (100 μM), quinidine (50 μM) and Ba (3 mM) and cold (10 °C) were most effective inhibitors of THIK-1 current (>50 % inhibition). In cell-attached patches with high KCl in the pipette and bath solutions, THIK-1 produced a small-conductance (~5 pS) channel with a weak inwardly rectifying current-voltage relationship. Halothane, bupivacaine and cold inhibited the single-channel activities of both THIK-1 and the 5-pS channel in TG neurons, whereas arachidonic acid augmented them. THIK-1 expressed in HEK293 cells and the 5-pS channels in TG neurons were insensitive to hypoxia. Reverse transcriptase-PCR, Western blot and immunocytochemical analyses suggested that THIK-1 mRNA and protein were expressed in TG neurons. These results show that THIK-1 is functionally expressed in TG neurons and contributes to the background K conductance. [ABSTRACT FROM AUTHOR]

Abstract: The dynamic fragmentation of planetary materials during impact into finite targets has been examined. A particle tracking algorithm was implemented to estimate the size and velocity of fragments ejected from the rear of the target. A total of 76 experiments were performed for four materials, target thicknesses of 7 mm–55 mm, and impact energies of 10 J–6810 J. Semi-empirical models were developed from non-dimensional groups to predict key experimental results. This includes the transformation of incoming projectile kinetic energy to the ejecta kinetic energy. The amount of impact energy converted to kinetic energy of ejecta was found to increase from 2% to 18% over the range of test conditions. Energy dissipated into expanding the field laterally was found to be small in comparison to the streamwise direction (∑KE y /∑KE x = 4%). Percentiles of the distribution of mass, momentum and kinetic energy with respect to ejecta lengths were also examined. Percentile ejecta lengths decrease for increasing normalized impact energy. Fits of the non-dimensional ejecta lengths provide reasonable collapse for the percentile values. Lastly, the cumulative distributions of mass, momentum and kinetic energy among normalized 50% length values were quantified. Exponential function forms were found to fit all of the data over the range over normalized length scales of 0.3–4. When integrated, this predicts the probability density distribution of mass, momentum, and kinetic energy among ejecta lengths for the range of experimental conditions in this study. This data is important in the development and validation of numerical models. [Copyright &y& Elsevier]

R4744 --> 717.5 --> Sex differences in obesity‐induced microvascular dysfunction have been reported, however, the mechanisms are poorly understood. We previously identified macrophages as key cells that mediate microvascular dysfunction in obesity. Interestingly, sex differences in the inflammatory response to obesity have also been described. The current aim was to define the interaction between biological sex and macrophages on obesity‐dependent microvascular dysfunction. We placed male and female mice (C57BL/6) on either a high‐fat diet to induce obesity or a low‐fat control diet. After twelve weeks mice were treated with either clodronate‐containing liposomes to deplete macrophages or PBS‐containing control liposomes. Macrophage depletion had no effect on body weight, glycemia, or mean arterial pressure, which were all increased by obesity in both male and female. Obesity also caused an expansion of the macrophage population in both male and female mesenteric perivascular adipose tissue, as quantified by flow cytometry, which was similarly attenuated by clodronate treatment. We then assessed microvascular function in third order mesenteric arterioles using pressure myography. The sensitivity of vasoconstriction to norepinephrine was increased by obesity in both male and female. Macrophage depletion dramatically attenuated vasoconstriction in male but only minimally affected vessels from females. In contrast, macrophage depletion had no effect on acetylcholine‐dependent vasodilation in either male or female. Taken together, these data show that macrophages contribute to obesity‐dependent microvascular hypercontractility in males but not females. [ABSTRACT FROM AUTHOR]

R2543 --> 616.2 --> Carotid body (CB) glomus cells serve as peripheral chemoreceptors that detect changes in arterial O2 pressure (pO2) and pH, and adjust the level of ventilation to help maintain a normal level of blood pO2 and pH. Severe levels of hypoxia and acidosis are well known to cause sustained rise in cytosolic Ca2+ concentration ([Ca2+]c) in CB glomus cells. We showed recently that isolated gloms cells exhibit spontaneous [Ca2+]c oscillations and that mild levels of hypoxia increase the frequency and amplitude of Ca2+oscillations to augment the secretory response. To understand how mild levels of acidosis regulate Ca2+signaling in glomus cells, we studied the effects of small changes in extracellular pH (pHo) on the kinetics of Ca2+oscillations and the roles of Cav, ASIC and TASK. A decrease in pHo from 7.4 to 7.3 (mild acidosis) and 7.2 (moderate acidosis) produced significant increases in the frequency and amplitude of Ca2+ oscillations without affecting the resting basal [Ca2+]c. These effects on Ca2+ oscillations were not blocked by 0.1 mM amiloride (an ASIC inhibitor) that blocked Na‐H exchange in glomus cells. Mild acidosis was associated with a small but significant inhibition of TASK current and cell depolarization. The increase in Ca2+oscillations produced by mild acidosis was strongly inhibited by nifedipine (1 µM; L‐type Cav inhibitor), as well as by TTA‐P2 (20 µM; T‐type Cav inhibitor). Mild acidosis (0.1 pH unit decrease) and mild hypoxia (~5% O2) produced similar levels of change in the kinetics of Ca2+oscillations and produced an additive effect on Ca2+oscillations. Our study shows that mild to moderate levels of acidosis inhibit TASK to increase Ca2+ influx via both L‐ and T‐type Cav, resulting in increased frequency and amplitude of Ca2+ oscillations. Our study also indicate that ASICs are not involved in the stimulatory effects of mild acidosis on Ca2+oscillations. [ABSTRACT FROM AUTHOR]

Abstract: Ejecta velocity measurements were made during impacts into solid planetary materials. Ejecta velocity fields overlie each other when normalized by , , and ; these correspond to the maximum velocity and median values of mass and kinetic energy among ejecta velocities. Semi-empirical models were developed to provide predictive capabilities of 10th, 50th, and 90th percentiles of the distributions of mass, momentum and kinetic energy with respect to ejecta velocity. Lastly, a functional equation describing the probability density distribution of mass, momentum and kinetic energy among ejecta velocities was derived. Data and predictive models are valuable in the development and validation of numerical models, where comparison between experiments and simulations rely on well characterized measurements. [Copyright &y& Elsevier]

Abstract: Velocity and size measurements of ejecta derived from impacts of railgun-launched projectiles into 10 mm thick gabbro tiles are examined. Fragmentation of the target and the ejecta velocity field are found to be governed by Hertzian fracture and the transfer of kinetic energy to the target. Over 90% of the total kinetic energy is contained above the average ejecta velocity and greater than 95% in angles bounded by Hertzian fracture. Log-normal distributions of the ejecta reveal that the kinetic energy transfer from projectile to ejecta is an organized process that spans over four orders of magnitude. The ejection angle that contains the most total kinetic energy coincides with the primary ejection angle, indicating the importance of larger plate-like fragments in the fragmentation process. Approximately 11–16% of energy to the target (initial − final kinetic energy of the projectile) is converted to the kinetic energy of fragments when the projectile does not perforate the target (≤52 J). The conversion to fragment kinetic energy increases near-linearly to ∼50% at an incoming projectile energy of 305 J. This reveals the importance of this energy conversion mechanism under these experimental conditions. [Copyright &y& Elsevier]

Abstract: The dynamic fragmentation of gabbro and granitoid tiles, and coarser and finer grained granitoid blocks have been examined for impact energies of 21–6180J. Intra-grain fragmentation and inter-granular frictional melting were observed to be common features of the fragmentation process. Consideration of analytical models indicate these temperatures are achievable under these moderate impact conditions. Median values of the number-based sub-10μm fines, and the number- and volume-based 10μm to 2mm fragments were compared with existing theoretical models predicting dominant fragment size. The simplistic model proposed by Grady predicts reasonably well the median fragment size for the volume-based distribution. More complex models are able to predict reasonably well median values for number-based distributions. Ultra-fine production was not predictable. These results suggest there are two distinct fragment-forming mechanisms during impact testing of natural materials. One mechanism is based on energy considerations of the bulk material, which produces the larger fragment sizes, and the other is associated with micro-scale comminution, which produces sub-10μm fines. [Copyright &y& Elsevier]

Abstract: Material-removal phenomena in quartz and albite under single-diamond contact conditions are examined. Results indicate that the fracture behaviour of albite is associated with thermal- and fracture-dominated micro-scale processes, leading to larger forces in the primary scratch direction, more energetic acoustic emission events, enhanced comminution, and smaller fragment sizes. Quartz was observed to have pressure and strength dominant micro-scale processes, with more blocky fracture surfaces, larger fragments, larger tensile z-forces, and more high-pressure-related phenomena. The results can be related to material properties (i.e., fracture toughness, hardness, and melting temperature). [Copyright &y& Elsevier]

A numerical approach combining finite element modeling and machine learning is used to inform the material performance of an alumina ceramic tile undergoing high-velocity impact. In this study, the alumina ceramic tile is simulated by incorporating a user-defined Johnson–Holmquist–Beissel (JHB) material model within the framework of smoothed particle hydrodynamics (SPH) in LS-DYNA finite element software. The implementation of the JHB model is verified by comparing equivalent stress–pressure responses through a single element simulation test. After implementation, the computational framework is simulated across our chosen range of conditions by matching the results from both plate impact experiments and ballistic testing from the literature. The computational model is then used to generate training data sets for an artificial neural network (ANN) to predict the residual velocity and projectile erosion for an alumina ceramic tile undergoing high-velocity impact in the SPH framework. The ANN is then used to perform a sensitivity analysis involving exploring the effect of mechanical properties (e.g., strength and shear modulus) and impact simulation geometries (e.g., thickness of ceramic tile) on material performance (i.e., residual projectile velocity and erosion). Overall, this study shows the capability of the FEM-ANN approach in studying the high-velocity impact on ceramic tiles and is applicable to guide the structural-scale design of ceramic-based protection systems. [ABSTRACT FROM AUTHOR]

This study explores the role of porosity in the impact deposition of a ceramic-reinforced metal-matrix (i.e., Al/B 4 C) composite coating fabricated via cold spraying. The Johnson–Holmquist–Beissel constitutive law and the modified Gurson–Tvergaard–Needleman model were used to describe the high strain-rate behavior of the boron carbide and the aluminum metal matrix during impact deposition, respectively. Within a finite element model framework, the Arbitrary Lagrangian–Eulerian technique is implemented to explore the roles of reinforcement particle size and velocity, and pore size and depth in particle retention by examining the post-impact crater morphology, penetration depth, and localized plastic deformation of the aluminum substrate. Results reveal that some degree of matrix porosity may improve particle retention. In particular, porosity near the surface facilitates particle retention at lower impact velocities, while kinetic energy dominates particle retention at higher deposition velocities. Altogether, these results provide insights into the effect of deposition variables (i.e., particle size, impact velocity, pore size, and pore depth) on particle retention that improves coating quality. [ABSTRACT FROM AUTHOR]

Abstract: The role of plastic deformation and fracture during small-scale, low-rate contact scenarios in gypsum is investigated. Results indicate that the hardness decreases with increasing load, on all axes, ranging from 216kg/mm2 at 0.25N to 91kg/mm2 at 4.91N on the (010) plane and from 122kg/mm2 at 0.98N to 75kg/mm2 at 4.91N on the (011) and (110) cleavage planes. Higher hardness values for lower loads are attributed to dislocation saturation and localized necking, which leads to densification and work-hardening. Transmitted light microscopy reveals that the decrease in hardness for increasing load is related to an increase in subsurface cracking along the (010) and (011) cleavage planes, enabling the indenter to penetrate deeper into the crystal. Coupled with an increase in subsurface cracking is an increase in surface smoothness as a result of increased plastic material flow beneath the indenter, with crack densities decreasing from 34% at a 0.25N load to 6% at a 4.91N loading. Raman spectroscopy reveals that the higher-hardness material comprises water-reduced forms of calcium sulphate: hemihydrate and α-CaSO4. Local temperatures required for the dehydration of gypsum range from 118 to 142°C, indicating such temperatures were reached during plastic flow, and related heat generation, of the material beneath the indenter under relatively quasi-static conditions. Evaporated water generates voids in the original crystal structure and enables the sulphate to deform more easily. [Copyright &y& Elsevier]

Abstract: The dynamic fragmentation of granite at impact energies of 6–28J is examined in this paper. Results indicate that more dense materials, or those with a higher quartz content, produce less fractured mass, and have larger dominant fragment sizes and smaller aspect ratios in their fragment probability distributions. Values of the peaks in fragment size distributions are in agreement with theoretical predictions. Examination of the fracture surfaces reveals information concerning transgranular cracking, crack bifurcation mechanisms and evidence of comminution of sub-micron K-feldspar and plagioclase fragments. Fractal dimensions of the cumulative distribution of fragment sizes were ≃2, indicating that comminution was a dominant fragmentation mechanism in these tests. Peaks in the probability distributions of sub-micron fragments on fracture surfaces reveal a limit of coherent fragments of approximately 0.60μm for plagioclase and K-feldspar. The smallest fragments found on the surfaces were approximately 0.30μm and this is considered to be the comminution limit for these materials. [Copyright &y& Elsevier]

Abstract: The dynamic fracture of natural polyphase ceramic (granite) blocks by high-speed impact at 207 m/s, 420 m/s and 537 m/s has been investigated. An electromagnetic railgun was used as the launch system. Results reveal that the number of fragments increases substantially, and the dominant length scale in their probability distributions decreases, as the impact energy is increased. Micro-scale studies of the fracture surfaces reveals evidence of localized temperatures in excess of 2000 K brought on by frictional melting via fracturing and slip along grain boundaries in orthoclase and plagioclase, and via transgranular fracture (micro-cracking) in quartz. The formation of SiO2- and TiO2-rich spheroids on fracture surfaces indicates that temperatures in excess of 3500 K are reached during fracture. [Copyright &y& Elsevier]

Multipoint fluctuating wall pressure measurements are used to examine the spanwise characteristics of the vortex shedding from yawed circular cylinders for yaw angles from α = 60 to 90° and for Reynolds numbers from 2.81 x 10 4to 5.61 x 10 4. The results indicate that yawing the cylinder to the mean flow direction causes the vortex shedding in the wake to become more disorderly. This, in turn, reduces the correlation length of the cylinder and causes the acoustic dipole sources in the cylinder wake to change from strongly tonal for α = 90 °to largely broadband for α = 60° Low-frequency pressure fluctuations were found to be associated with reasonably well- organized structures that develop on the upstream end of the cylinder and span several cylinder diameters in length. These structures appear to disrupt the vortex shedding process along the span of the cylinder. [ABSTRACT FROM AUTHOR]

Analysis of a typical semiarid mountain system recharge (MSR) setting demonstrates that geochemical tracers help resolve the location, rate, and seasonality of recharge as well as ground water flowpaths and residence times. MSR is defined as the recharge at the mountain front that dominates many semiarid basins plus the often-overlooked recharge through the mountain block that may be a significant ground water resource; thus, geochemical measurements that integrate signals from all flowpaths are advantageous. Ground water fluxes determined from carbon-14 (14C) age gradients imply MSR rates between 2 × 106 and 9 × 106 m3/year in the Upper San Pedro Basin, Arizona, USA. This estimated range is within an order of magnitude of, but lower than, prior independent estimates. Stable isotopic signatures indicate that MSR has a 65% ± 25% contribution from winter precipitation and a 35% ± 25% contribution from summer precipitation. Chloride and stable isotope results confirm that transpiration is the dominant component of evapotranspiration (ET) in the basin with typical loss of more than 90% of precipitation-less runoff to ET. Such geochemical constraints can be used to further refine hydrogeologic models in similar high-elevation relief basins and can provide practical first estimates of MSR rates for basins lacking extensive prior hydrogeologic measurements. [ABSTRACT FROM AUTHOR]

Semi-arid and arid rivers typically exhibit increasing salinity levels downstream, a trend often attributed to irrigated agriculture, primarily due to evapotranspiration. In contrast, the results of our investigations in one salinized river suggest that geological sources of salt added by groundwater discharge are more important than agricultural effects. We performed detailed synoptic sampling of the Upper Rio Grande—Rio Bravo, an arid-climate river with significant irrigated agriculture, and identified a series of salinity increases localized at the distal ends of sedimentary basins. Using Cl/Br, Ca/Sr, 87Sr/86Sr, and 36Cl/Cl ratios and δ234U values as environmental tracers, we show that these increases result from localized discharge of high-salinity groundwater of a sedimentary brine source. These groundwater fluxes, while very small (<1 m3s-1), are the dominant solute input and, combined with downstream evapotranspirative concentration, result in salinization. Furthermore, 36Cl/Cl ratios and δ234U values for these brines are close to secular equilibrium, indicating brine ages on the order of millions of years. The recognition of a substantial geologic salinity source for the Rio Grande implies that alternative salinity management solutions, such as interception of saline groundwater, might be more effective in reducing salinity than changes in agricultural practices. [ABSTRACT FROM AUTHOR]

A study was conducted at the Fresh Kills landfill, Staten Island, New York to investigate the use of B and Li isotopes as tracers of mixing and flow in the groundwater environment. Four end-member waters are present at the Fresh Kills: freshwater, seawater, a geochemically distinct transitional groundwater (that occurs in the zone of mixing between seawater and freshwater) and landfill leachate. The δ11B and δ6Li values of end-member waters are distinct and have isotopic compositions that reflect the solute sources: freshwater δ11B∼+30‰, δ6Li∼−22‰; transition zone groundwaters δ11B∼+20‰, δ6Li∼−27‰; seawater δ11B+40 to +75‰, δ6Li−37 to−44‰; leachate δ11B∼+10‰ (δ6Li not determined). Those wells influenced by seawater exhibited a clear chemical mixing trend, with seawater contributions ranging from 3 to 85%. Well waters with a high percentage of seawater (>30%) had δ11B values that were within 1‰ of the seawater value (+40‰), whereas a trend of increasing δ11B values (+55 to +75‰) was observed for wells with a lower percentage of seawater (<30%). δ6Li values for well waters impacted by mixing with seawater ranged from−37 to−44‰, significantly more negative than pure seawater (−31‰). This deviation from the isotopic composition of seawater, for both δ11B and δ6Li values, represents non-conservative behavior and is likely the result of isotopic fractionation during ion exchange reactions. The wide range of δ11B and δ6Li values and the distinct isotopic compositions of end-member waters makes B and Li isotopes useful for recognizing solute sources, however isotopic fractionation may limit their use as simple tracers of groundwater flow and mixing. [Copyright &y& Elsevier]

Several families in the beetle suborder Adephaga have an aquatic life style and are commonly grouped in the “Hydradephaga,” but their monophyly is contentious and relationships between and within these families are poorly understood. Here we present full-length 18S rRNA sequence for 84 species of Hydradephaga, including representatives of most major groups down to the tribal level, and a total of 68 species of the largest family, Dytiscidae. Using a direct optimization method for the alignment of length-variable regions, the preferred tree topology was obtained when the cost of gaps and the cost of nucleotide changes were equal, and three hypervariable regions of 18S rRNA were downweighted by a factor of five. Confirming recent molecular studies, the Hydradephaga were found to be monophyletic, indicating a single colonization of the aquatic medium. The most basal group within Hydradephaga is Gyrinidae, followed in a comb-like arrangement by families Haliplidae, Noteridae, Amphizoidae, and Hygrobiidae plus Dytiscidae. Under most alignment parameters, Hygrobiidae is placed amid Dytiscidae in an unstable position, suggesting a possible data artifact. Basal relationships within Dytiscidae are not well established, nor is the monophyly of subfamilies Hydroporinae and Colymbetinae. In contrast, relationships at the genus level appear generally well supported. Despite the great differences in the rates of change and the significant incongruence of the phylogenetic signal in conserved vs hypervariable regions of the 18S rRNA gene, both contribute to establish relationships at all taxonomic levels. [Copyright &y& Elsevier]

This work presents a new class of neural network models constrained by biological levels of sparsity and weight-precision, and employing only local weight updates. Concept learning is accomplished through the rapid recruitment of existing network knowledge — complex knowledge being realised as a combination of existing basis concepts. Prior network knowledge is here obtained through the random generation of feed-forward networks, with the resulting concept library tailored through distributional bias to suit a particular target class. Learning is exclusively local — through supervised Hebbian and Winnow updates — avoiding the necessity for back-propagation of error and allowing remarkably rapid learning. The approach is demonstrated upon concepts of varying difficulty, culminating in the well-known Monks and LED benchmark problems. [ABSTRACT FROM AUTHOR]

Provides common sense measures in the detection and prevention of cheating on multiple-choice examinations. Computer program generating multiple version exams; Typical data on errors of student pairs; Random seating; Widely-spaced seatings.

Reports on the preparation of L-lactate dehydrogenase. Catalytic behavior toward the representative gamma-keto acid substrates; Comparison of the level of protein expression; Resistance to thermal denaturation; Support of the validity of ion-pairing approach.

Crater cataloging is an important yet time-consuming part of geological mapping. We present an automated Crater Detection Algorithm (CDA) that is competitive with expert-human researchers and hundreds of times faster. The CDA uses multiple neural networks to process digital terrain model and thermal infra-red imagery to identify and locate craters across the surface of Mars. We use additional post-processing filters to refine and remove potential false crater detections, improving our precision and recall by 10% compared to Lee (2019). We now find 80% of known craters above 3km in diameter, and identify 7,000 potentially new craters (13% of the identified craters). The median differences between our catalog and other independent catalogs is 2%–4% in location and diameter, in-line with other inter-catalog comparisons. The CDA has been used to process global terrain maps and infra-red imagery for Mars, and the software and generated global catalog are available at https://doi.org/10.5683/SP2/CFUNII. • We developed a new automated crater detection algorithm using ResUNET neural networks. • The crater detection algorithm processes digital terrain model data and optical imagery data. • The performance of the algorithm is on-par with expert human researchers. [ABSTRACT FROM AUTHOR]

This study improves upon understanding of the effects of reinforcing particle content and microstructure on the mechanical properties and failure of low-pressure cold spray fabricated tungsten carbide-nickel (WC-Ni) metal matrix composite (MMC) coatings. Image analyses were performed on scanning electron microscope (SEM) micrographs of the coatings to characterize the microstructure and measure the total interfacial area between the reinforcing WC particles and the Ni metal matrix, the mean free path between the particles, the average particle size, and the porosity of the coating. Uni-axial quasi-static tensile testing was conducted on the as-sprayed coatings. The tensile stresses that were measured were coupled with the evolving strains that were calculated by using the digital image correlation (DIC) technique. The results showed that mechanical properties, namely tensile strength and Young's modulus, of the composite coatings increased with increasing WC content in the coatings. The increases were due to the refined microstructural features that occurred with the decrease in the porosity of the coating that was caused by significant consolidation of the Ni metal matrix. Furthermore, this increase in strength and Young's modulus was also related to the increase in the interfacial area between the reinforcing carbide particles and the metal matrix that was caused by the increase in carbide content in the coating, a decrease in the average size of the carbides in the coating, and a reduction of the mean free path between the carbide particles. A framework was presented to elicit the micro-macro relationships between the microstructure and the tensile strength of the cold-sprayed composite coatings. Based on the developed framework, two distinct coating mechanical strength regimes were observed, indicating a significant increase in the tensile strength of the coatings that were comprised of more than 30 wt% WC due to the refined microstructure of the coatings. The higher value tensile strength regime was also confirmed by the larger average mechanical energy absorbed to failure under tensile loading and lower damage accumulation. This collection of data of mechanical properties and the microstructures presented in this study are important to validate numerical-based failure models for cold-sprayed composite coatings. Altogether, the results of this study will enhance understanding of the sensitivity of mechanical response of a composite coating to microstructural changes. • Properties of cold-sprayed metal matrix composite coatings • Micro-macro relationships between coating microstructure and the tensile strength • Understanding mechanical response of a composite coating to microstructural changes [ABSTRACT FROM AUTHOR]

Cyclonic windstorms profoundly affect forest structure and function throughout the tropics and subtropics. Remote sensing techniques and vegetation indices (VIs) have improved our ability to characterize cyclone impacts over broad spatial scales. Although VIs are useful for understanding changes in forest cover, their consistency on detecting changes in vegetation cover is not well understood. A better understanding of the similarities and differences in commonly used VIs across disturbance events and forest types is needed to reconcile the results from different studies. Using Landsat imagery, we analyzed the change between pre- and post-typhoon VI values (ΔVIs) of four VIs for five typhoons (local name of cyclones in the North Pacific) that affected the Fushan Experimental Forest of Taiwan. We found that typhoons varied in their effect on forest canopy cover even when they had comparable trajectories, wind speeds, and rainfall. Most VIs measured a decrease in forest cover following typhoons, ranging from −1.18% to −19.87%; however, the direction of ΔVI–topography relationships varied among events. All typhoons significantly increased vegetation heterogeneity, and ΔVI was negatively related to pre-typhoon VI across all typhoons. Four of the five typhoons showed that more frequently affected sites had greater VI decreases. VIs ranged in their sensitivity to detect typhoon-induced changes in canopy coverage, and no single VI was most sensitive across all typhoons. Therefore, we recommend using VIs in combination—for example Normalized Difference Infrared Index (NDII) and Enhanced Vegetation Index (EVI), when comparing cyclone-disturbance-induced changes in vegetation cover among disturbances and across forests. [ABSTRACT FROM AUTHOR]

Permanent forest dynamics plots have provided valuable insights into many aspects of forest ecology. The evaluation of their representativeness within the landscape is necessary to understanding the limitations of findings from permanent plots at larger spatial scales. Studies on the representativeness of forest plots with respect to landscape heterogeneity and disturbance effect have already been carried out, but knowledge of how multiple disturbances affect plot representativeness is lacking—particularly in sites where several disturbances can occur between forest plot censuses. This study explores the effects of five typhoon disturbances on the Fushan Forest Dynamics Plot (FFDP) and its surrounding landscape, the Fushan Experimental Forest (FEF), in Taiwan where typhoons occur annually. The representativeness of the FFDP for the FEF was studied using four topographical variables derived from a digital elevation model and two vegetation indices (VIs), Normalized Difference Vegetation Index (NDVI) and Normalized Difference Infrared Index (NDII), calculated from Landsat-5 TM, Landsat-7 ETM+, and Landsat-8 OLI data. Representativeness of four alternative plot designs were tested by dividing the FFDP into subplots over wider elevational ranges. Results showed that the FFDP neither represents landscape elevational range (<10%) nor vegetation cover (<7% of the interquartile range, IQR). Although disturbance effects (i.e., ΔVIs) were also different between the FFDP and the FEF, comparisons showed no under- or over-exposure to typhoon damage frequency or intensity within the FFDP. In addition, the ΔVIs were of the same magnitudes in the plots and the reserve, and the plot covered 30% to 75.9% of IQRs of the reserve ΔVIs. Unexpectedly, the alternative plot designs did not lead to increased representation of damage for 3 out of the 4 tested typhoons and they did not suggest higher representativeness of rectangular vs. square plots. Based on the comparison of mean Euclidian distances, two rectangular plots had smaller distances than four square or four rectangular plots of the same area. Therefore, this study suggests that the current FFDP provides a better representation of its landscape disturbances than alternatives, which contained wider topographical variation and would be more difficult to conduct ground surveys. However, upscaling needs to be done with caution as, in the case of the FEF, plot representativeness varied among typhoons. [ABSTRACT FROM AUTHOR]

Understanding the structure–property relationship of the human cranium is crucial for enhancing personalized head protection design and improving injury prevention criteria. This study presents a thorough spatial analysis of cranial morphology at both the macro- and micro-scale through micro-CT scanning. Two statistical quantifiers (i.e., Cortico-trabecular thickness (CoTb.Th) and Cortico-trabecular spacing (CoTb.Sp)) are defined here to characterize the micro-structural morphology in both the cortical and cancellous tables. A new adaptive layer segmentation method is proposed that considers the micro-structural variation to quantify the porosity threshold between the inner table, the diploë and the outer table. Then, statistical analysis was employed to investigate the interaction between donor information (e.g., age, sex, and sample extraction location) and structural characteristics (maximum and average porosity, CoTb.Th and CoTb.Sp). The morphological results revealed that the peak parallel porosity of 55 ± 30% can be found in the diploë region, while the perpendicular porosity remained essentially stable and fluctuated between a range of 10–15%. Furthermore, the layer segmentation results demonstrated that the porosity threshold between the inner table and the diploë was 29.14 ± 3.93%, and 46.50 ± 4.80% between the diploë and the outer table. In addition, the statistical analyses indicated that age ( p < 0.01 ) and sex ( p < 0.05 ) were the most influential factors affecting maximum and average porosity. The novelty of this work stems from the comprehensive understanding of the morphological features of human crania, which is needed to advance the physical surrogate models of human skull, contributing to the mechanical testing of head protection devices and improvement of injury criteria. [ABSTRACT FROM AUTHOR]

This study compares the fatigue life of a 7475-T7351 aluminum alloy lower wall plate in an aircraft beam structure under alternating corrosion and fatigue conditions to universal fatigue life. It incorporates a corrosive environment and variable amplitude fatigue loads. The current study uses the "beach marking" technique and visual inspection to monitor crack propagation and evaluate the corrosive environment's impact on fatigue life and damage tolerance. The experimental results indicate that during the fatigue crack initiation and penetration stages, the corrosion environment does not significantly impact the fatigue life of the beam structure because of the protection from uniform oxide films, epoxy primer, and sealants at joints. In the crack propagation stage, the corrosive environment speeds up crack growth compared to universal fatigue tests. Additionally, a "hysteresis effect" in alternating corrosion and fatigue tests shows the fatigue crack growth rate changing discontinuously, caused mainly by corrosion dissolving slip bands at the crack tip. Altogether, this study provides new insights into the influence of alternating corrosion and variable amplitude load on an aircraft beam structure's fatigue life and damage tolerance. [ABSTRACT FROM AUTHOR]

Presents a method for assigning likely culpability for the cheating which occurs on multiple-choice exams and describes campus reaction to updated university regulations governing exam security. Description of prior method of demonstrating copying was taking place; Use of errors in common, exact errors in common and differences ratio; What analyses of different examinations found.

This study offers novel insights into the Mode I tensile response of an alumina ceramic through the use of computational modeling and the flattened Brazilian disk (FBD) experiments. A modified hybrid finite-discrete element method (HFDEM) is developed, integrating a coupled damage and friction cohesive model and a microscopic stochastic fracture model with a Weibull strength distribution by Monte Carlo simulation. The model is used to simulate direct tensile failure processes under quasi-static loading conditions, providing qualitative and quantitative predictions of direct tensile failure processes of an alumina ceramic. Concurrently, quasi-static flattened Brazilian disk tests (indirect tensile tests) are performed on a standard MTS machine coupled with a high-speed camera. The modified HFDEM model is also applied to reproduce the FBD experiments, and our simulated tensile strength is consistent with the experimental results. The results of the modified HFDEM model show three kinds of phenomena (i.e. , "underestimation", "reasonable estimation", and "overestimation" of the indirect tensile strength) and four different types of associated fracture and fragment patterns of FBD testing. The integration of simulation and experimental results reveal relationships between fracture patterns, fragment geometry, tensile strength, and indirect tensile strength. The fracture and fragmentation patterns derived from our modified HFDEM model can be utilized to analyze the "tensile strength" measured in BD testing. Overall, this research offers important insights and direction for future Brazilian disk experiments and tensile strength assessments, enhancing our comprehension of ceramic failure mechanisms under tensile loadings. • Hybrid finite-discrete element method is modified by incorporating friction and flaws. • Our model probes over, reasonable, and underestimation in tensile strength. • Simulations and tests reveal links between fracture patterns, fragment geometry and tensile strength. • Study offers insights for Brazilian disk tests and tensile strength measurements in brittle materials. [ABSTRACT FROM AUTHOR]