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Passive materials in human skeletal muscle tissues play an important role in force output of skeletal muscles. This paper introduces a multiscale modeling framework to investigate how age‐associated variations on microscale passive muscle components, including microstructural geometry (e.g., connective tissue thickness) and material properties (e.g., anisotropy), influence the force output and deformations of the continuum skeletal muscle. We first define a representative volume element (RVE) for the microstructure of muscle and determine the homogenized macroscale mechanical properties of the RVE from the separate mechanical properties of the individual components of the RVE, including muscle fibers and connective tissue with its associated collagen fibers. The homogenized properties of the RVE are then used to define the elements of the continuum muscle model to evaluate the force output and deformations of the whole muscle. Conversely, the regional deformations of the continuum model are fed back to the RVE model to determine the responses of the individual microscale components. Simulations of muscle isometric contractions at a range of muscle lengths are performed to investigate the effects of muscle architectural changes (e.g., pennation angles) due to aging on force output and muscle deformation. The correlations between the pennation angle, the shear deformation in the microscale connective tissue (an indicator for the lateral force transmission), the angle difference between the fiber direction and principal strain direction and the resulting shear deformation at the continuum scale, as well as the force output of the skeletal muscle are also discussed. [ABSTRACT FROM AUTHOR]

Plant allometries help us to understand resource allocation in plants and provide insight into how communities are structured. For woody species, a triangular allometric relationship between seed size and leaf size occurs in which all combinations are all possible, except for species with big seeds and small leaves (Cornelissen ). This relationship is thought to be a consequence of between-habitat variation in abiotic conditions., In this study, we tested if the triangular relationship between seed mass and leaf area holds for annual species, and if variation in soil productivity and light (measured as Ellenberg indicator values: EIVs) is driving this relationship., We show that the triangular relationship also holds for annuals, which suggests that the allometric combinations between leaf area and seed mass are conserved across life-forms., The triangular relationship was driven by between habitat variation in soil productivity. This means that as soil productivity increases, plants with bigger leaves could have either big or small seeds. However, in low soil productivity habitats, plants are constrained in their options, and plants with small leaves can only have small seeds., A is available for this article. [ABSTRACT FROM AUTHOR]

Reliable modelling of above-ground net primary production ( aNPP) at fine resolution is a significant challenge. A promising avenue for improving process models is to include response and effect trait relationships. However, uncertainties remain over which leaf traits are correlated most strongly with aNPP., We compared abundance-weighted values of two of the most widely used traits from the leaf economics spectrum (specific leaf area and leaf dry matter content) with measured aNPP across a temperate ecosystem gradient., We found that leaf dry matter content ( LDMC) as opposed to specific leaf area ( SLA) was the superior predictor of aNPP ( R2 = 0·55)., Directly measured in situ trait values for the dominant species improved estimation of aNPP significantly. Introducing intraspecific trait variation by including the effect of replicated trait values from published databases did not improve the estimation of aNPP., Our results support the prospect of greater scientific understanding for less cost because LDMC is much easier to measure than SLA., A is available for this article. [ABSTRACT FROM AUTHOR]

Questions How has vegetation species diversity and species composition changed between 1965 and 2012/13 in acidic and calcareous grasslands? What has driven this change in vegetation? Location A 2400-km2 area around Sheffield, northern England. Methods In 1965 a survey was conducted to describe grassland vegetation of the Sheffield region. We repeated this survey in 2012/13, revisiting acidic and calcareous grassland sites (455 quadrats). Climate, N and sulphur deposition, cattle and sheep stocking rates, soil pH, altitude, aspect and slope were considered to be potential drivers of variation in vegetation. We analysed temporal changes in vegetation and examined relationships with spatial and temporal variation in driver variables. Results Both acidic and calcareous grasslands showed clear changes in species composition between the two time periods. In acidic grasslands there was no significant change in richness but there were declines in diversity. There were significant increases in Ellenberg N. Nitrogen deposition and grazing were identified as potential drivers of spatial and temporal patterns but it was not possible to discriminate the respective impacts of potential drivers. In calcareous grasslands there were declines in species richness, diversity and appropriate diversity indices. Climate and soil pH were identified as potential drivers of spatial and temporal patterns. Conclusions Despite only small site losses compared to other surveys in the UK, especially within the national park, both calcareous and acidic grasslands showed very clear changes in species composition. In acidic grasslands, high abundance of Pteridium aquilinum was a particular problem and had increased considerably between the two survey periods. Atmospheric N deposition and grazing were identified as drivers of species diversity. A number of calcareous grasslands showed signs of reduced management intensity leading to scrub invasion. [ABSTRACT FROM AUTHOR]

We describe a novel method for quantifying ecosystem drivers that potentially compromise the effectiveness of agri-environment schemes. We use three sources of data that for many countries are already in the public domain: governmental agricultural statistics, which provide a quantitative assessment of farming intensity in the 'working landscape', data on threat status and species distribution for plants and butterflies from conservation agencies and similar bodies and functional traits of plant species abstracted from published data bases., Changes in land use alter ecosystem processes which in turn modify both biodiversity and representation of functional types at the landscape scale. We interpret functional shifts to quantify important ecological drivers of floristic and faunal change and their causal land use origins., We illustrate the power of this approach by means of a worked example. We demonstrate that despite conservation policies to counteract them, eutrophication, identified by leaf nitrogen content, and abandonment, correlated with plant canopy height, are still causing biodiversity loss to native higher plants and butterflies in the English countryside., We use our analyses to suggest how conservation policies can be made more effective and discuss how similar approaches could be applied elsewhere. [ABSTRACT FROM AUTHOR]

The recognition that colorectal cancer ( CRC) is a heterogeneous disease in terms of clinical behaviour and response to therapy translates into an urgent need for robust molecular disease subclassifiers that can explain this heterogeneity beyond current parameters ( MSI, KRAS, BRAF). Attempts to fill this gap are emerging. The Cancer Genome Atlas ( TGCA) reported two main CRC groups, based on the incidence and spectrum of mutated genes, and another paper reported an EMT expression signature defined subgroup. We performed a prior free analysis of CRC heterogeneity on 1113 CRC gene expression profiles and confronted our findings to established molecular determinants and clinical, histopathological and survival data. Unsupervised clustering based on gene modules allowed us to distinguish at least five different gene expression CRC subtypes, which we call surface crypt-like, lower crypt-like, CIMP-H-like, mesenchymal and mixed. A gene set enrichment analysis combined with literature search of gene module members identified distinct biological motifs in different subtypes. The subtypes, which were not derived based on outcome, nonetheless showed differences in prognosis. Known gene copy number variations and mutations in key cancer-associated genes differed between subtypes, but the subtypes provided molecular information beyond that contained in these variables. Morphological features significantly differed between subtypes. The objective existence of the subtypes and their clinical and molecular characteristics were validated in an independent set of 720 CRC expression profiles. Our subtypes provide a novel perspective on the heterogeneity of CRC. The proposed subtypes should be further explored retrospectively on existing clinical trial datasets and, when sufficiently robust, be prospectively assessed for clinical relevance in terms of prognosis and treatment response predictive capacity. Original microarray data were uploaded to the ArrayExpress database (http://www.ebi.ac.uk/arrayexpress/ ) under Accession Nos E- MTAB-990 and E- MTAB-1026. © 2013 Swiss Institute of Bioinformatics. Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Purpose: To design a computer-controlled, magnetic resonance (MR)-compatible foot pedal device that allows in vivo mapping of changes in morphology and in strain of different musculoskeletal components of the lower leg under passive, isometric, concentric, and eccentric contractions. Materials and Methods: A programmable servomotor in the control room pumped hydraulic fluid to rotate a foot-pedal inside the magnet. To validate the performance of the device, six subjects were imaged with gated velocity-encoded phase-contrast (VE-PC) imaging to investigate the dynamics of muscle and aponeurotic structures. Results: Artifact-free VE-PC imaging clearly delineated different muscle compartments by differences in distribution of mechanical strains. High repeatability of contraction cycles allowed establishing that fascicles lengthened 6.1% more during passive compared with eccentric contractions. Aponeurosis separation during passive (range between three locations: −2.6≈1.3 mm) and active (range: −2.4≈1.6 mm) contractions were similar but significantly different from concentric (range: −0.9≈3.3 mm), with proximal and distal regions showing mostly negative values for the first two modes, but positive for the last. Conclusion: The device was sufficiently robust and artifact-free to accurately assess, using VE-PC imaging, physiologically important structure and dynamics of the musculotendon complex. J. Magn. Reson. Imaging 2012;36:405-410. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Purpose To devise a method using velocity encoded phase contrast MRI and MR-compatible dynamometry, for in vivo estimation of elastic properties of the human Achilles tendon and to assess within-session and day-to-day repeatability of this technique. Materials and Methods Achilles tendon force and calcaneus-movement-adjusted displacement were measured during a submaximal isometric plantarflexion in 4 healthy subjects, four repeated trials each. The measured force-length (F-L) relationship was least-squares fitted to a cubic polynomial. Typical error was calculated for tendon displacement at multiple force levels, stiffness from the 'linear region,' and transition point from the displacement point separating the linear and nonlinear parts of the curve. Results Displacements of the tendon were determined up to a maximum force of 500N, with mean stiffness of 234 ± 53 N/mm, mean transition point of 2.70 ± 0.23 mm and maximum tendon displacement of 3.38 mm. Variability of tendon displacement was not dependent on the force level. Overall typical errors were 0.09 mm and 0.16 mm for within-session and between days, respectively. Typical error of transition point was 0.05 mm and 0.14 mm. Stiffness had typical errors of 47.24 N/mm and 51.95 N/mm. The tendon cross-sectional area and calcaneus displacement were found to be very significant factors in minimizing the individual differences in F-L curves. Conclusion The method yielded F-L relationships, stiffness, and transition point values that showed good within and day-to-day repeatability. The technique compared well with the more conventional one using ultrasonography. Its reliability indicates potential for measuring tendon structural changes after an injury, disease, and altered loading. J. Magn. Reson. Imaging 2008;28:1039-1045. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Purpose To develop and compare phase-contrast (PC) and spin-tag (ST) MR imaging techniques for accurate quantification of velocity and displacement distribution in the muscle tendon complex of the lower leg during isometric contractions under in vivo conditions, in healthy subjects and subjects with atrophy. Materials and Methods Techniques were developed to acquire PC and ST dynamic images, gated to the force exerted by a subject during isometric contraction. Algorithms were optimized for correction of phase shading errors. Flow velocity quantification was validated in phantoms and ex vivo rabbit muscles. Trajectories of pixels calculated from PC images were compared with those in ST images. Velocity distributions were determined in healthy muscles, those atrophied by four weeks of suspension, and during physiotherapy-induced recovery. Results The technique developed allowed acquisition of images retrospectively gated to the isometric contraction performed with the subject in the scanner. Significant phase shading errors in PC images (≈3 cm/second over the field of view) were reduced to the background noise level by the correction algorithm. Tissue trajectories calculated from PC images agreed very well with those from ST images both in human and excised animal tissues. Peak velocities in atrophied muscles were significantly lower compared to the preatrophy state but recovered to baseline values after six weeks of therapy. Conclusion We show the feasibility of monitoring muscle velocity and tissue displacement during voluntary contractions in humans under in vivo conditions using MR tissue motion mapping methods. The clinical feasibility of this technique in monitoring atrophied muscle is also demonstrated. J. Magn. Reson. Imaging 2004;20:1008-1019. © 2004 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Question: How do lawn floras compare with those of semi-natural grasslands? Are the compositions of lawn toms determined by local, within-garden factors (e.g. lawn management and size) or by regional factors (e.g. climate and location)? Are lawn floras nested (like semi-natural grasslands) or not (like cultivated parts of gardens)? Are there gradients of species composition within lawns? Location: Sheffield, UK. Methods: We examined the composition of the floras of entire lawns and of two 1-m² lawn quadrats in 52 gardens. Results: A total of 159 species of vascular plants was recorded, 60 of them only once. Most lawn species were forbs, but most lawn cover consisted of grasses. Lawn species were predominantly natives. Bigger lawns had more species, but richness was not closely linked to other environmental or management variables. Composition of lawn floras varied with altitude, with woodland and wetland plants more common in the higher west of the city, and weeds of waste ground in the east. The species-area curve derived from 1-m² lawn quadrats was very similar to that of semi-natural grasslands. Lawn quadrats were significantly nested, with rarer species mostly confined to more species-rich quadrats. Trampling-tolerant Poa annua was more abundant in the part of the lawn nearer the house. Conclusions: In most respects, lawns behaved much more like semi-natural grasslands than like cultivated flower beds and borders. Species composition of lawns is strongly influenced by local climate. Most lawns show an internal gradient of composition, linked to a gradient of intensity of use. [ABSTRACT FROM AUTHOR]

1. To determine whether rarity and decline is linked to organism ecology, associations have been examined between butterfly larval host-plant competitive, stress-tolerant, ruderal ( C-S-R) strategies and butterfly biology. 2. Associations have been sought between mean C-S-R scores for larval host plants with butterfly life history, morphology and physiology variables, resource use, population attributes, geography, and conservation status. Comparisons are carried out across species and controlled for phylogenetic patterning. 3. Butterfly biology is linked to host-plant strategies. An increasing tendency of a butterfly's host plants to a particular strategy biases that butterfly species to functionally linked life-history attributes and resource breadth and type. In turn, population attributes and geography are significantly and substantially affected by host choice and the strategies of these host plants. 4. The greatest contrast is between butterfly species whose host plants are labelled C and R strategists and those whose host plants are labelled S strategists. Increasingly high host-plant C and R strategy scores bias butterflies to rapid development, short early stages, multivoltinism, long flight periods, early seasonal emergence, higher mobility, polyphagy, wide resource availability and biotope occupancy, open, areally expansive, patchy population structures, denser distributions, wider geographical ranges, resistance to range retractions as well as to increasing rarity in the face of environmental changes. Increasing host-plant S strategy scores have reversed tendencies, biasing those butterfly species to extended development times, fewer broods, short flight periods, smaller wing expanse and lower mobility, monophagy, restricted resource exploitation and biotope occupancy, closed, areally limited populations with typical metapopulation structures, sparse distributions, and limited geographical ranges, range retractions, and increased rarity. 5. Species with S strategy host plants are species vulnerable to current environmental changes and species of conservation concern. [ABSTRACT FROM AUTHOR]

Summary • Associations between specific leaf area (SLA), leaf water content (LWC) and leaf thickness (LT) in 77 species were analysed to identify which of these traits gave a better indicator value of general plant resource-use strategy within the flora of central-western Argentina, in which succulent species are common. • When all species were considered together, SLA and LWC were not significantly correlated. All high-SLA tender-leafed species showed high LWC. Low SLA, however, was associated both with low LWC (sclerophyllous species) and with high LWC (succulents). When succulents were excluded, the association between SLA and LWC was significant and positive. A similar trend was found for a mixed set of nonsucculent species from other floras of the world. • In the Argentine data set, SLA and LT, but not LWC, were significantly correlated with species’ scores along a multivariate axis of plant resource-use strategy. • Because of its clearer ecological interpretation and its applicability across different floras, SLA appears to be the best candidate for inclusion in large comparative databases. [ABSTRACT FROM AUTHOR]

Examines the role of productivity and disturbance on the invisibility of plant communities. Identification of the functional characteristics of invaders to the different type of invasion; Identity and distribution of plant invaders on consolidation stage; Enhancement of invasion on the availability of the resources by the resident vegetation.

A key element of most recently proposed plant strategy schemes is an axis of resources capture, usage and availability. In the search for a simple, robust plant trait (or traits that will allow plants to be located on this axis, specific leaf area and other leaf traits, the relationships between them, and their ability to predict position on the resource use axis. Specific leaf area is found to suffer from a number of drawbacks: it is both very variable between replicates and much influenced by leaf thickness. Leaf dry-matter content (sometimes referred to as tissue density) is much less variable, largely independent of leaf thickness and a better predictor of location on an axis of resource capture, usage and availability. However, it is not clear how useful dry matter content will be outside northwest Europe, usage and availability. However, it is not clear how useful dry matter content will be outside northwest Europe, and in particular in dry climates with many succulents. [ABSTRACT FROM AUTHOR]

1 Using data from a survey of over 10 000 1-m2 quadrats in a 3000-km2 area, we examined the relationship between abundance and range for the vascular plant flora of central England. 2 At the level of the whole landscape, abundance was not related to local, regional or national range. Local, regional and national range were closely related to each other. 3 At the level of the whole landscape, range was significantly and positively related to both niche breadth (expressed as the range of habitats exploited) and to habitat availability, although niche breadth appeared to be more important. Abundance was not related to niche breadth or habitat availability. Since specialist species are mainly confined to uncommon habitats (especially wetlands), we conclude that the relationship between range and niche breadth is not an artefact of widespread species passively sampling more habitats. 4 At the level of individual habitat types, significant positive relationships between range and abundance were common. These relationships remained after controlling for the effects of phylogeny. For predominantly annual weed communities, the relationship was linear, but for perennial communities it was markedly ‘upper triangular’, i.e. all combinations of range and abundance were found except wide range/low abundance. The evidence suggests that this difference can be attributed to the greater mobility of annual weeds. [ABSTRACT FROM AUTHOR]

Commonness and rarity among British butterflies have been examined by relating features of biology and ecology to geographical distribution. No single attribute totally differentiates between common and rare species. However, several characteristics which are correlated with abundance appear likely to influence the capacity of species to exploit the artificial, disturbed and productive habitats which have been created by modern land-use and now occupy much of the landscape. Several features of geographical distribution, perhaps indicative of climatic tolerance are also correlated with abundance. Species of butterfly which are recorded from the greatest number of 10-km squares in England, Scotland and Wales are relatively large, form ‘open’ or migratory populations, exploit larval food plants of productive habitats, have rapidly maturing larvae, hibernate as a pupa or an amigo and extend into parts of NW Europe with relatively low summer temperatures. Two grouping of common butterflies are distinguished: (a) those which produce several broods per year, are polyphagous, utilize larval food plants of disturbed habitats and have a short-lived imago (Pieridae subfamily Pierinae); (b) single-brooded, monophagous species in which the imago is long-lived and the larvae exploit species of food plants of undisturbed habitats (Nymphalidale sub-family Nymphalini). By contrast, the rarest species of butterfly are variously large or small, tend to occur in ‘closed’ populations, produce a single brood per year, exploit larval food plants of unproductive habitats and produce long-lived larvae, with a life span exceeding that of the imago. Typically, these larvae feed on only one species or genus of food plant. Butterflies and higher plants appear to have exhibited a similar range of reactions to modern land-use; changes in the length and quality for food capture, development and reproduction provide a common explanation for these parallel responses. It is argued that the classification of butterflies will be useful as a prediction of the ecology and changing abundance of individual species and will assist in recognizing conservation priorities. The criteria used for butterflies are applicable to other major animal taxa, and provide a conceptual link to theories already applied to vascular plants. [ABSTRACT FROM AUTHOR]

This paper has examined the stability of the relationship between monetary magnitudes and exchange market pressure. First a single, general estimating equation was derived and applied to seven advanced countries. In the 2SLS estimates, the coefficients of the money demand variables were generally not significant. Of the money supply variables, coefficients of the rates of change in the home money multiplier and domestic credit were almost always significant and had signs predicted by the monetary approach.
Tests for stability suggest that the relationship between exchange-market pressure and the excess demand for money within an economy may not be stable over time, at least under the present specification. This seems to be especially true during periods of severe disruption in international monetary relations. In two of the countries, the coefficient specifically relating exchange market pressure to growth in domestic credit underwent wide variations during the breakdown of the Bretton Woods system between 1971 and 1973. For two others, shifts coincided with the monetary crises of 1968-69. There is some evidence that shifts in the level of this coefficient accompanied changes in sterilization policy or shifts in the demand for money. Evidence of this kind suggests that the relationship between monetary variables and exchange market pressure is more consistent with a weak than with a strong version of the monetary approach. [ABSTRACT FROM AUTHOR]

1 Using the data in a recently published seed bank database for north-west Europe, we describe how a species’ seed bank behaviour can be characterized by a single ‘longevity index’, and investigate how representative the information in the database is of the north-west European flora. We also test the hypotheses that seeds of short-lived species are more persistent than those of long-lived species, and long-lived seeds are characteristic of species living in disturbed habitats. 2 The data are not representative of the north-west European flora as a whole; they are a fair reflection of a research effort that has been largely directed towards grassland and arable weeds. Data for rare species, non-agricultural habitats in general and wetlands, rocky habitats and native woodland in particular, are scarce or absent. 3 Annuals and biennials almost always have more persistent seeds than related perennials, and this difference is most striking when, as in Anagallis arvensis and Aphanes arvensis, the short-lived species have moved well away from the ‘core’ habitat of the family. Confamilial monocarps and polycarps do not differ consistently in seed mass. 4 Gradients of habitat disturbance are accompanied by predictable changes in seed persistence, which are themselves often (but not always) accompanied by parallel shifts in seed size. These results suggest that increasing habitat disturbance (i.e. increasing density-independent mortality) always selects for increased seed persistence, confirming both theory and previous analyses. However, increased seed persistence is not always associated with reduced seed size. This is because persistence depends not only on seed size, but on other traits, many of them physiological. In many habitats the probability of seed burial is strongly linked to seed size and shape, but in arable habitats cultural practices have broken this link. [ABSTRACT FROM AUTHOR]

This paper analyzes the relationship between the dollar and the pound-sterling during one of the most volatile episodes in the history of floating currencies: March 1919 to April 1925. The pound had been the international vehicle currency prior to World War I and retained this characteristic in large measure during the inter-war period. The dollar, on the other hand, was the currency of the strongest and most stable economy of the day and was rising in importance in international finance. As the only major currency that remained tied to gold throughout the period, the U. S. dollar became the standard by which the worth of other currencies was measured. [ABSTRACT FROM AUTHOR]

Human aging results in a progressive decline in the active force generation capability of skeletal muscle. While many factors related to the changes of morphological and structural properties in muscle fibers and the extracellular matrix (ECM) have been considered as possible reasons for causing age‐related force reduction, it is still not fully understood why the decrease in force generation under eccentric contraction (lengthening) is much less than that under concentric contraction (shortening). Biomechanically, it was observed that connective tissues (endomysium) stiffen as ages, and the volume ratio of connective tissues exhibits an age‐related increase. However, limited skeletal muscle models take into account the microstructural characteristics as well as the volume fraction of tissue material. This study aims to provide a numerical investigation in which the muscle fibers and the ECM are explicitly represented to allow quantitative assessment of the age‐related force reduction mechanism. To this end, a fiber‐level honeycomb‐like microstructure is constructed and modeled by a pixel‐based Reproducing Kernel Particle Method (RKPM), which allows modeling of smooth transition in biomaterial properties across material interfaces. The numerical investigation reveals that the increased stiffness of the passive materials of muscle tissue reduces the force generation capability under concentric contraction while maintains the force generation capability under eccentric contraction. The proposed RKPM microscopic model provides effective means for the cellular‐scale numerical investigation of skeletal muscle physiology. Novelty Statement: A cellular‐scale honeycomb‐like microstructural muscle model constructed from a histological cross‐sectional image of muscle is employed to study the causal relations between age‐associated microstructural changes and age‐related force loss using Reproducing Kernel Particle Method (RKPM).The employed RKPM offers an effective means for modeling biological materials based on pixel points in the medical images and allow modeling of smooth transition in the material properties across interfaces.The proposed microstructure‐informed muscle model enables quantitative evaluation on how cellular‐scale compositions contribute to muscle functionality and explain differences in age‐related force changes during concentric, isometric and eccentric contractions. [ABSTRACT FROM AUTHOR]