Mice are one of the most commonly used laboratory animals, with an extensive array of disease models in existence, including for many neuromuscular diseases. The hindlimb is of particular interest ...due to several close muscle analogues/homologues to humans and other species. A detailed anatomical study describing the adult morphology is lacking, however. This study describes in detail the musculoskeletal geometry and skeletal muscle architecture of the mouse hindlimb and pelvis, determining the extent to which the muscles are adapted for their function, as inferred from their architecture. Using I2KI enhanced microCT scanning and digital segmentation, it was possible to identify 39 distinct muscles of the hindlimb and pelvis belonging to nine functional groups. The architecture of each of these muscles was determined through microdissections, revealing strong architectural specialisations between the functional groups. The hip extensors and hip adductors showed significantly stronger adaptations towards high contraction velocities and joint control relative to the distal functional groups, which exhibited larger physiological cross sectional areas and longer tendons, adaptations for high force output and elastic energy savings. These results suggest that a proximo-distal gradient in muscle architecture exists in the mouse hindlimb. Such a gradient has been purported to function in aiding locomotor stability and efficiency. The data presented here will be especially valuable to any research with a focus on the architecture or gross anatomy of the mouse hindlimb and pelvis musculature, but also of use to anyone interested in the functional significance of muscle design in relation to quadrupedal locomotion.
Retention harvests are preferred over traditional clear‐cuts for sustainable forest management because maintenance and re‐establishment of native forest biodiversity is a priority. However, few ...studies have examined long‐term responses of biotic assemblages to retention harvest at particular sites.
We studied the effects of decreasing initial harvest intensities (clear‐cut, 10%, 20%, 50% and 75% dispersed green‐tree retention) on carabid beetle assemblages relative to assemblage changes in un‐harvested control stands in four successionally ordered cover‐types of boreal mixedwood forest. We also studied temporal effects by comparing assemblages over a 16‐year pre‐ and post‐harvest period, using data collected through monitoring of the EMEND (Ecosystem Management Emulating Natural Disturbance) experiment in NW Alberta, Canada.
Retention harvests affected assemblages differently across cover‐types. Assemblages in compartments harvested in the earlier forest successional stages of ‘deciduous’ or ‘deciduous with spruce understorey’ converged towards the pre‐harvest structure of corresponding controls over time. In contrast, beetle assemblages in ‘mixed’ or ‘conifer’ compartments, that represent later successional forest, moved steadily away from their pre‐harvest structures during the first post‐harvest decade. These latter assemblages became strikingly more similar to those under deciduous canopies by 15‐year post‐harvest.
Synthesis and applications. Variable retention harvests will promote and maintain biodiversity better than clear‐cutting. Higher retention levels promote faster recovery, but towards fauna typical of early successional forest in all cover‐types. Carabids associated with conifer habitats are less resistant to impact from harvesting than are those from broadleaf deciduous forest. Therefore, conifer‐dominated stands present the most significant management challenge and higher retention levels are required to promote rapid and effective faunal recovery in such late successional stands.
Variable retention harvests will promote and maintain biodiversity better than clear‐cutting. Higher retention levels promote faster recovery, but towards fauna typical of early successional forest in all cover‐types. Carabids associated with conifer habitats are less resistant to impact from harvesting than are those from broadleaf deciduous forest. Therefore, conifer‐dominated stands present the most significant management challenge and higher retention levels are required to promote rapid and effective faunal recovery in such late successional stands.
Clear-cutting alters natural ecosystem processes by reducing landscape heterogeneity. It is the dominant harvesting technique across the boreal zone, yet understanding of how environmental ...heterogeneity and beta diversity are structured in forest ecosystems and post-clear cut is lacking. We use ground-dwelling arthropods as models to determine how natural succession (progression from deciduous to mixed to coniferous cover types) and clear-cutting change boreal forests, exploring the role of environmental heterogeneity in shaping beta diversity across multiple spatial scales (between-cover types and between-stands of the same cover type (1600 to 8500 m), between-plots (100 to 400 m) and within-plots (20 to 40 m)). We characterise environmental heterogeneity as variability in combined structural, vegetational and soil parameters, and beta diversity, as variability in assemblage composition. Clear-cutting homogenised forest environments across all spatial scales, reducing total environmental heterogeneity by 35%. Arthropod beta diversity reflected these changes at larger scales suggesting that environmental heterogeneity is useful in explaining beta diversity both between-cover types and between-stands of the same cover type. However, at smaller scales, within- and between-plots spider beta diversity reflected the lower environmental heterogeneity in regenerating stands, whereas staphylinid and carabids assemblages were not homogenised 12 years post-harvest. Differences in environmental heterogeneity and staphylinid beta diversity between cover types were also important at small scales. In regenerating stands, we detected a subtle yet notable effect of pre-felling cover type on environmental heterogeneity and arthropods, where pre-felling cover type accounted for a significant amount of variance in beta diversity, indicating that biological legacies (e.g. soil pH reflecting pre-harvest conditions) may have a role in driving beta diversity even 12 years post-harvest. This study highlights the importance of understanding site history when predicting impacts of change in forest ecosystems. Further, to understand drivers of beta diversity we must identify biological legacies shaping community structure.
Evidence from model organisms and clinical genetics suggests coordination between the developing brain and face, but the role of this link in common genetic variation remains unknown. We performed a ...multivariate genome-wide association study of cortical surface morphology in 19,644 individuals of European ancestry, identifying 472 genomic loci influencing brain shape, of which 76 are also linked to face shape. Shared loci include transcription factors involved in craniofacial development, as well as members of signaling pathways implicated in brain-face cross-talk. Brain shape heritability is equivalently enriched near regulatory regions active in either forebrain organoids or facial progenitors. However, we do not detect significant overlap between shared brain-face genome-wide association study signals and variants affecting behavioral-cognitive traits. These results suggest that early in embryogenesis, the face and brain mutually shape each other through both structural effects and paracrine signaling, but this interplay may not impact later brain development associated with cognitive function.
Patients with ischemic stroke or transient ischemic attack (TIA) are at increased risk for future cardiovascular events despite current preventive therapies. The identification of insulin resistance ...as a risk factor for stroke and myocardial infarction raised the possibility that pioglitazone, which improves insulin sensitivity, might benefit patients with cerebrovascular disease.
In this multicenter, double-blind trial, we randomly assigned 3876 patients who had had a recent ischemic stroke or TIA to receive either pioglitazone (target dose, 45 mg daily) or placebo. Eligible patients did not have diabetes but were found to have insulin resistance on the basis of a score of more than 3.0 on the homeostasis model assessment of insulin resistance (HOMA-IR) index. The primary outcome was fatal or nonfatal stroke or myocardial infarction.
By 4.8 years, a primary outcome had occurred in 175 of 1939 patients (9.0%) in the pioglitazone group and in 228 of 1937 (11.8%) in the placebo group (hazard ratio in the pioglitazone group, 0.76; 95% confidence interval CI, 0.62 to 0.93; P=0.007). Diabetes developed in 73 patients (3.8%) and 149 patients (7.7%), respectively (hazard ratio, 0.48; 95% CI, 0.33 to 0.69; P<0.001). There was no significant between-group difference in all-cause mortality (hazard ratio, 0.93; 95% CI, 0.73 to 1.17; P=0.52). Pioglitazone was associated with a greater frequency of weight gain exceeding 4.5 kg than was placebo (52.2% vs. 33.7%, P<0.001), edema (35.6% vs. 24.9%, P<0.001), and bone fracture requiring surgery or hospitalization (5.1% vs. 3.2%, P=0.003).
In this trial involving patients without diabetes who had insulin resistance along with a recent history of ischemic stroke or TIA, the risk of stroke or myocardial infarction was lower among patients who received pioglitazone than among those who received placebo. Pioglitazone was also associated with a lower risk of diabetes but with higher risks of weight gain, edema, and fracture. (Funded by the National Institute of Neurological Disorders and Stroke; ClinicalTrials.gov number, NCT00091949.).
The background cold electron density plays an important role in plasma and wave dynamics. Here, we investigate an event with clear modulation of the particle fluxes and wave intensities by background ...electron density irregularities based on Van Allen Probes observations. The energies at the peak fluxes of protons and Helium ions of 100 eV to several keV are well correlated with the total electron density variation. Intense electromagnetic ion cyclotron (EMIC) and magnetosonic (MS) waves are simultaneously observed in the high‐density regions and disappear in low‐density regions. Based on the linear theory of wave growth, the EMIC waves are generated by the ~10 keV protons, while most MS waves are generated by the positive gradient of proton phase space density at several hundred eV in the high‐density regions. Our results indicate the importance of background plasma density structures in generation of plasma waves by unstable ion distributions.
Plain Language Summary
The background electron density decreases away from the Earth with a sharp boundary in the density profile, which is defined as the plasmapause. Density irregularities are frequently observed near the plasmapause, and these density structures are believed to play an important role in the generation and propagation of plasma waves. In this letter, we report an event with clear modulation of particle fluxes and electromagnetic ion cyclotron (EMIC), MS as well as the electrostatic waves by the background plasma density structure at a plasmapause crossing near the postdusk magnetic equator based on Van Allen Probe B observation on 9 October 2013. It is shown that the energies of peak fluxes for proton and helium suprathermal populations are well correlated with the background electron density variations. In addition, EMIC and MS waves are simultaneously observed in high plasma density regions but vanish in low‐density regions. Furthermore, the broadband electrostatic waves occur in the density depletion regions. Our simulations indicate that the variations of electromagnetic waves are caused by the wave generation conditions in association with the density irregularities.
Key Points
Van Allen Probe B observed an electron density structure near the plasmaspheric plume region at the postdusk sector
The suprathermal ion fluxes were modulated by the electron density structure showing evidence of transverse ion heating
EMIC and MS waves were simultaneously observed in the high‐density regions while electrostatic waves were present in the low‐density regions
A preliminary study of the genus
Rosulabryum
J.R. Spence in Chile is presented, with brief species descriptions, notes on ecology and distributions, and a taxonomic key. The following 12 species are ...confirmed with vouchered specimens;
Rosulabryum andicola
(Hook.) Ochyra,
Rosulabryum billarderii
(Schwägr.) J.R. Spence,
Rosulabryum campylothecium
(Taylor) J.R. Spence,
Rosulabryum capillare
(Hedw.) J.R. Spence,
Rosulabryum coloratum
(Müll. Hal.) J.R. Spence,
Rosulabryum densifolium
(Brid.) Ochyra,
Rosulabryum longidens
(Thér.) J.R. Spence,
Rosulabryum macrophyllum
(Cardot & Broth.) Ochyra,
Rosulabryum perlimbatum
(Cardot) Ochyra,
Rosulabryum puconense
(Herzog & Thér.) J.R. Spence,
Rosulabryum rubens
(Mitt.) J.R. Spence, and
Rosulabryum torquescens
(Bruch
ex
De Not.) J.R. Spence.
Rosulabryum canariense
(Brid.) Ochyra is tentatively excluded as the Chilean material can be referred to
R. coloratum
. Similarly,
Rosulabryum viridescens
(Welw. & Duby) Ochyra is tentatively excluded since the Chilean plants do not match the African type, but instead appear to be atypical plants of
R. campylothecium
.
Drift‐resonance wave‐particle interaction is a fundamental collisionless plasma process studied extensively in theory. Using cross‐spectral analysis of electric field, magnetic field, and ion flux ...data from the Van Allen Probe (Radiation Belt Storm Probes) spacecraft, we present direct evidence identifying the generation of a fundamental mode standing poloidal wave through drift‐resonance interactions in the inner magnetosphere. Intense azimuthal electric field (Eφ) oscillations as large as 10mV/m are observed, associated with radial magnetic field (Br) oscillations in the dawn‐noon sector near but south of the magnetic equator at L∼5. The observed wave period, Eφ/Br ratio and the 90° phase lag between Br and Eφ are all consistent with fundamental mode standing Poloidal waves. Phase shifts between particle fluxes and wave electric fields clearly demonstrate a drift resonance with ∼90 keV ring current ions. The estimated earthward gradient of ion phase space density provides a free energy source for wave generation through the drift‐resonance instability. A similar drift‐resonance process should occur ubiquitously in collisionless plasma systems. One specific example is the “fishbone” instability in fusion plasma devices. In addition, our observations have important implications for the long‐standing mysterious origin of Giant Pulsations.
Key Points
Unambiguous identification of drift‐resonance in magnetosphere
Broad implications for ring current and ground observations
Drift‐resonance similar to fishbone instability in Tokamak
Life-history traits influence colonization, persistence, and extinction of species on islands and are important aspects of theories predicting the geographical distribution and evolution of species. ...We used data collected from a large freshwater lake (1,413 km2) in central Canada to test the effects of island area and isolation on species richness and abundance of carabid beetles as a function of body size, wing length, and breeding season. A total of 10,018 individual beetles from 37 species were collected during the frost-free period of 2013 using transects of pitfall traps on 30 forested islands ranging in area from 0.2 to 980.7 ha. Life-history traits improved the predictive ability and significantly modified the shape of species-area and abundance-area curves. Abundance and richness of small-bodied (< 13.9 mm), macropterous (winged), and spring-breeding species decreased with island area and increased with isolation. In contrast, richness and abundance of larger-bodied (> 14.0 mm) and flightless species increased with area, but not isolation. Body size of female Carabus taedatus Fabricius, the largest-bodied species, was positively related to island area, while body size on the adjacent mainland was most similar to that on smaller islands. Overall, species with large body size and low dispersal ability, as indicated by flightlessness, were most sensitive to reductions in area. We suggest that large-bodied, flightless species are rare on small islands because habitat is less suitable for them and immigration rates are lower because they depend on freshwater drift for dispersal to islands.
Although natural disturbance has been widely adopted as a template for forest management that protects biodiversity, this hypothesis has not been adequately tested. We compared litter-dwelling ...arthropod assemblages (Coleoptera: Carabidae and Staphylinidae; Araneae) in aspen-dominated stands originating as clear-cuts or wildfires across three age classes (1–2, 14–15, and 28–29 years old) to test whether the post-harvest and post-fire assemblages converged following disturbances, and to compare faunal succession. These findings were compared to data about epigaeic arthropods in old and mature pyrogenic aspen stands (>70 years old) to determine whether diversity and community composition of arthropods from the younger age-classes approached what may have been typical pre-disturbance conditions. The resulting data-set of almost 27,000 arthropods and 230 species showed convergence in most taxa, and some general similarities between 28- and 29-year-old stands and old and mature stands. However, not all taxa responded similarly, and faunal succession following clear-cutting appeared to progress more rapidly than following wildfire. Rarefaction-estimated diversity was elevated in 1–2-year-old stands, compared to unharvested stands, reflecting a mix of closed-canopy and open-habitat species. Non-metric multi-dimensional scaling ordinations showed that samples from young wildfire disturbed stands (1–2 years old) included more variable assemblages than all other study sites, and contained species that may depend on unique post-fire habitat characteristics. The fauna of old and mature stands exhibited low diversity, but contained species with limited dispersal abilities, and species tied to old-growth habitats such as dead wood. Harvesting systems that do not allow adequate recovery following a first harvesting pass, or do not maintain microhabitat features associated with older fire-origin forests, may threaten persistence of some elements of boreal arthropod faunas.
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