Characterisation of a phenomenological model for commercial pneumatic muscle actuators

This study focuses on the parameter characterisation of a three-element phenomenological model for commercially available pneumatic muscle actuators (PMAs). This model consists of a spring, damping and contractile element arranged in parallel. Data collected from static loading, contraction and relaxation experiments were fitted to theoretical solutions of the governing equation for the three-element model resulting in prediction profiles for the spring, damping and contractile force coefficient. For the spring coefficient, K N/mm, the following relationships were found: K = 32.7 ? 0.0321P for 150 ≤ P ≤ 314 kPa and K = 17 + 0.0179P for 314 ≤ P ≤ 550 kPa. For the damping coefficient, B Ns/mm, the following relationship was found during contraction: B = 2.90 for 150 ≤ P ≤ 550 kPa. During relaxation, B = 1.57 for 150 ≤ P ≤ 372 kPa and B = 0.311 + 0.00338P for 372 ≤ P ≤ 550. The following relationship for the contractile force coefficient, F _ce N, was also determined: F _ce = 2.91P+44.6 for 150 ≤ P ≤ 550 kPa. The model was then validated by reasonably predicting the response of the PMA to a triangular wave input in pressure under a constant load on a dynamic test station.     

An anatomical subject-specific FE-model for hip fracture load prediction

In order to reduce the socio-economic burden induced by osteoporotic hip fractures, finite element models have been evaluated as an additional diagnostic tool for fracture prediction. For a future clinical application, the challenge is to reach the best compromise between model relevance and computing time. Based on this consideration, the current study focused on the development and validation of a subject-specific FE-model using an original parameterised generic model and a specific personalization method. A total of 39 human femurs were tested to failure under a quasi-static compression in stance configuration. The corresponding FE- models were generated and for each specimen the numerical fracture load (FFEM) was compared with the experimental value (FEXP), resulting in a significant correlation (FEXP = 1.006 FFEM with r2 = 0.87 and SEE = 1220 N, p < 0.05) obtained with a reasonable computing time (30 mn). Further in vivo study should confirm the ability of this FE-model to improve the fracture risk prediction.     

Seven-year survey of sleep timing in Russian children and adolescents: chronic 1-h forward transition of social clock is associated with increased social jetlag and winter pattern of mood seasonality

Previous studies indicate that solar clock (daily changes in the Earth’s surface illumination) is a main zeitgeber for human circadian system. It has been shown that human biological clock is weakly adjusted to such changes in social clock as daylight saving time (DST). There are two changes of social clock in Russian Federation: on 25 March 2011, DST has been replaced by permanent DST (DSTp), which was subsequently revoked on 26 October 2014 (non-DSTp). These manipulations with social clock may lead to prolonged disturbances of human circadian system. Our hypothesis is that during period of DSTp, the dissociation between social and biological clocks was greatest as compared with DST and non-DSTp periods. Here, we examine the effects of DSTp on the sleep timing, social jetlag (SJL), academic performance, and winter and summer seasonality of mood and behavior of 10–24-year-old inhabitants of European North of Russia. A cross-sectional retrospective analysis of questionnaire data (n = 7968) was performed using chi squared-test and analysis of covariance. Our findings indicate that SJL (F_2,7967 = 31.9; p < 0.0001; η² = 0.009), and winter pattern of mood seasonality (χ²_2,7967 = 10.5; p < 0.01) were increased in adolescents during the period of DSTp as compared with DST and non-DSTp periods. The largest increase in SJL was occurred in ages between 10 and 17-year-olds. The finding suggests that increase in SJL can be attributed to a later rise time on free days (F_2,7967 = 44.9; p < 0.0001; η² = 0.012). Similar changes were observed in three subsamples obtained in Syktyvkar, Petrozavodsk, and Vorkuta. Effect sizes of studied relationships were small or very small. The greatest effect sizes (η² ～ 0.05) were observed in Arctic city of Vorkuta indicating that in polar region, solar clock is still stronger zeitgeber for human circadian system, than the social clock. In conclusion, we have shown for the first time that there is a greatest dissociation between social and biological clocks during the period of DSTp which potentially exerts a negative influence on adolescents’ sleep habits, mood, and behavior. Our data indicate that “non-DSTp” social clock system most suitable for prevention dissociation between social and biological clocks.     

Allometric equations for maximum filtration rate in blue mussels Mytilus edulis and importance of condition index

The relationship between body dry weight (W) and shell length (L) of blue mussels, Mytilus edulis, can be expressed by the condition index (CI = W/L ³) which varies from population to population and during the year. Here, we examine the influence of CI on the relationships between maximum filtration rate (F, l h^?1), W (g), and L (mm) as described by the equations: F _W  = aW ^b and F _L  = cL ^d , respectively. This is done by using available and new experimental laboratory data on M. edulis obtained by members of the same research team using different methods and controlled diets of cultivated algal cells. For all data, it was found that F _W  = 6.773W ^0.678 and F _L  = 0.00135L ^2.088 which are very similar to equations for mussels with ‘medium condition’ (CI = 4–6 mg cm^?3): F _W  = 6.567W ^0.681 and F _L  = 0.00150L ^2.051, with b- and d-values within a few percent of the theoretically expected of 2/3 and 2, respectively. Further, based on the present data, we propose a correction factor expressed by the empirical relation F _W /F _L  = 0.3562CI^2/3 which implies that F _W tends to underestimate the actual filtration rate (F _L ) when CI < 4.70 and to overestimate the filtration rate when CI > 4.70.     

Landscape discontinuities influence the population structure of Acer opalus ssp. obtusatum Waldst. & Kit. ex Willdenow

The major goal of landscape genetics is to understand how landscape structure genetic variation in natural populations. We investigated molecular diversity in Acer opalus subsp. obtusatum sampled from 95 sites using 14 nuclear microsatellite loci. The average number of alleles per nuclear microsatellite locus differed among sampling sites; the number was high (4.9 alleles) in populations from the Basilicata and Molise regions, where heterozygosity was also high (0.679, Molise; 0.669, Basilicata). Differentiation between sites was often low (mean F_ST = 0.220), indicating few genetic differences between most sites. There was a clear excess of homozygotes (mean H_o = 0.450, mean H_e = 0.513) and a relatively high F_IS (mean = 0.451), suggesting a consistent level of inbreeding in many A. opalus subsp. obtusatum populations. There was a significant pattern of isolation by distance across the study area (Mantel test; R² = 0.0662, P < 0.001). Two assignment methods (Structure and Geneland) produced some similarities in their definitions of population structure, especially for populations from the Campania and Tuscany regions. These two important genetic discontinuities were not associated with any physical barriers.     

Would you say “yes” in the evening? Time-of-day effect on response bias in four types of working memory recognition tasks

Across a wide range of tasks, cognitive functioning is affected by circadian fluctuations. In this study, we investigated diurnal variations of working memory performance, taking into account not only hits and errors rates, but also sensitivity (d’) and response bias (c) indexes (established by signal detection theory). Fifty-two healthy volunteers performed four experimental tasks twice – in the morning and in the evening (approximately 1 and 10 h after awakening). All tasks were based on Deese–Roediger–McDermott paradigm version dedicated to study working/short-term memory distortions. Participants were to memorize sets of stimuli characterized by either conceptual or perceptual similarity, and to answer if they recognized subsequent stimulus (probe) as an “old” one (i.e. presented in the preceding memory set). The probe was of three types: positive, negative or related lure. In two verbal tasks, memory sets were characterized by semantic or phonological similarity. In two visual tasks, abstract objects were characterized by a number of overlapping similarities or differed in only one detail. The type of experimental material and the participants’ diurnal preference were taken into account. The analysis showed significant effect of time of day on false alarms rate (F_(1,50) = 5.29, p = 0.03, η_p² = 0.1) and response bias (F_(1,50) = 11.16, p = 0.002, η_p² = 0.18). In other words, in the evening participants responded in more liberal way than in the morning (answering “yes” more often). As the link between variations in false alarms rate, response bias and locus coeruleus activity was indicated in literature before, we believe that our data may be interpreted as supporting the hypothesis that diurnal fluctuations in norepinephrine release have effect on cognitive functioning in terms of decision threshold.     

In silico approaches to evaluate the molecular properties of organophosphate compounds to inhibit acetylcholinesterase activity in housefly

Organophosphate compounds (OPC) have become the primary choice as insecticides and are widely used across the world. Additionally, OPCs were also commonly used as a chemical warfare agent that triggers a great challenge to public safety. Exposure of OPCs to human causes immediate excitation of cholinergic neurotransmission through transient elevation of synaptic acetylcholine (ACh) levels and accumulations. Likewise, prolonged exposure of OPCs can affect the processes in immune response, carbohydrate metabolism, cardiovascular toxicity, and several others. Studies revealed that the toxicity of OPCs was provoked by inhibition of acetylcholinesterase (AChE). Therefore, combined in silico approaches – pharmacophore-based 3D-QSAR model; docking and Molecular Dynamics (MD) – were used to assess the precise and comprehensive effects of series of known OP-derived compounds together with its ?log LD₅₀ values. The selected five-featured pharmacophore model – AAHHR.61 – displayed the highest correlation (R² = .9166), cross-validated coefficient (Q² = .8221), F = 63.2, Pearson-R = .9615 with low RMSE = .2621 values obtained using five component PLS factors. Subsequently, the well-validated model was then used as a 3D query to search novel OPCs using a high-throughput virtual screening technique. Simultaneously, the docking studies predicted the binding pose of the most active OPC in the MdAChE binding pocket. Additionally, the stability of docking was verified using MD simulation. The results revealed that OP22 and predicted lead compounds bound tightly to S315 of MdAChE through potential hydrogen bond interaction over time. Overall, this study might provide valuable insight into binding mode of OPCs and hit compounds to inhibit AChE in housefly.     

Pharmacophore mapping,molecular docking and QSAR studies of structurally diverse compounds as CYP2B6 inhibitors

Pharmacophore mapping, molecular docking and quantitative structure–activity relationship (QSAR) studies were carried out for a structurally diverse set of 48 compounds as CYP2B6 inhibitors. The generated best pharmacophore hypotheses from the three methods of conformer generation (FAST, BEST and conformer algorithm based on energy screening and recursive buildup) indicate the importance of two features, namely, hydrogen bond acceptor [electron-rich centre] and ring aromaticity. The distance between the two centres of the important features for ideal inhibitors varied from 5.82 to 6.03 Å. The chemometric tools used for the QSAR analysis were genetic function approximation (GFA) and genetic partial least squares. The developed QSAR models indicate the importance of an electron-rich centre, size of molecule, impact of branching and ring system and distribution of charges in the molecular surface. The docking study confirms the importance of an electron-rich centre for binding with the iron atom of the cytochrome enzyme. A GFA model with spline option was found to be the best model based on internal validation as well as the r ² _{m (overall)} criterion (Q ² = 0.772, r ² _{m (overall)} = 0.774). According to the external prediction statistics (R ² _pred = 0.876), another GFA-derived model with spline option outperforms the remaining models.     

Interactive graph-cut segmentation for fast creation of finite element models from clinical ct data for hip fracture prediction

In this study, we propose interactive graph cut image segmentation for fast creation of femur finite element (FE) models from clinical computed tomography scans for hip fracture prediction. Using a sample of N = 48 bone scans representing normal, osteopenic and osteoporotic subjects, the proximal femur was segmented using manual (gold standard) and graph cut segmentation. Segmentations were subsequently used to generate FE models to calculate overall stiffness and peak force in a sideways fall simulations. Results show that, comparable FE results can be obtained with the graph cut method, with a reduction from 20 to 2–5 min interaction time. Average differences between segmentation methods of 0.22 mm were not significantly correlated with differences in FE derived stiffness (R² = 0.08, p = 0.05) and weakly correlated to differences in FE derived peak force (R² = 0.16, p = 0.01). We further found that changes in automatically assigned boundary conditions as a consequence of small segmentation differences were significantly correlated with FE derived results. The proposed interactive graph cut segmentation software MITK-GEM is freely available online at https://simtk.org/home/mitk-gem.     

Coping with shift work-related circadian disruption: A mixed-methods case study on napping and caffeine use in Australian nurses and midwives

ABSTRACT

Introduction: Two of the most ubiquitous fatigue countermeasures used by shift-working nurses are napping and caffeine. This mixed-methods case study investigated the ways nurses and midwives utilised napping and caffeine countermeasures to cope with shift work, and associated sleep, physical health and psychological health outcomes.

Materials and Methods: N = 130 Australian shift-working nurses and midwives (mean age = 44 years, range = 21–67, 115F, 15M) completed the Standard Shiftwork Index. A sub-set of 22 nurses and midwives completed an in-depth interview.

Results: Nearly 70% of participants reported napping. Those who napped during night shifts had significantly less total sleep time before (F_2,75 = 5.5, p < 0.01) and between days off (F_2,82 = 3.9, p < 0.05). By the end of the night shift, average hours of time awake were significantly less for prophylactic and on-shift nappers compared to non-nappers (F_2,85 = 97.2, p < 0.001). Since starting shift work, the percentage of high caffeine consumers (>400 mg/day) increased from 15% to 33% of the sample and an average of 4 (SD = 2) caffeinated beverages per day was reported. Increased caffeine consumption was associated with greater sleep disturbance (r = 0.26, p < 0.05), psychological distress (r = 0.37, p < 0.001), abdomen pain (r = 0.27, p < 0.05) and weight gain since starting shift work (r = 0.25, p < 0.05). Interviews confirmed these relationships and revealed that caffeine consumption on night shift was common, whereas napping on night shift was dependent on a number of factors including ability to sleep during the day.

Conclusion: This study identified reasons shift workers chose to engage in or abstain from napping and consuming caffeine, and how these strategies related to poor sleep and health outcomes. Further research is required to help develop recommendations for shift workers regarding napping and caffeine consumption as fatigue countermeasures, whilst taking into account the associated hazards of each strategy.     

Habent Fata Sua: The Rise and Fall of Garden Plants

Background: Rare cactus in the Americas and other species worldwide are threatened species because of their high level of habitat specialisation, narrow distribution range and continuing population decline.

Aims: To identify management units (MUs) based on genetic variability and demographic structure in order to propose assertive conservation actions for Mammillaria crucigera and to provide a model case study for other species that are under similar threats.

Methods: We genotyped through eight microsatellite loci in 171 individuals and described demographic structures in six populations of this cactus based on plots of 1 m².

Results: Across populations with a mean density of 2.6 m^?2 and a total of ~500 individuals counted, 30% of the individuals were reproductive (diameter >2 cm). The total heterozygosity was low (H_O = 0.54), but the inbreeding coefficient (F_IS = 0.29) and the allele diversity (N_A = 20) were high. Four genetic groups were distinguished, although considering the demographic structure, we propose three MUs.

Conclusions: It is critical to maintain the genetic connectivity within and among MUs, which can only be achieved through cooperation between government authorities and local habitants to halt the degradation and further destruction of the remnant populations. Searching MUs allows the identification of critical areas for conservation issues for all species whose extant populations are in a fragmented landscape.     

Pharmacophore generation,atom-based 3D-QSAR,molecular docking and molecular dynamics simulation studies on benzamide analogues as FtsZ inhibitors

FtsZ is an appealing target for the design of antimicrobial agent that can be used to defeat the multidrug-resistant bacterial pathogens. Pharmacophore modelling, molecular docking and molecular dynamics (MD) simulation studies were performed on a series of three-substituted benzamide derivatives. In the present study a five-featured pharmacophore model with one hydrogen bond acceptors, one hydrogen bond donors, one hydrophobic and two aromatic rings was developed using 97 molecules having MIC values ranging from .07 to 957 μM. A statistically significant 3D-QSAR model was obtained using this pharmacophore hypothesis with a good correlation coefficient (R² = .8319), cross validated coefficient (Q² = .6213) and a high Fisher ratio (F = 103.9) with three component PLS factor. A good correlation between experimental and predicted activity of the training (R² = .83) and test set (R² = .67) molecules were displayed by ADHRR.1682 model. The generated model was further validated by enrichment studies using the decoy test and MAE-based criteria to measure the efficiency of the model. The docking studies of all selected inhibitors in the active site of FtsZ protein showed crucial hydrogen bond interactions with Val 207, Asn 263, Leu 209, Gly 205 and Asn-299 residues. The binding free energies of these inhibitors were calculated by the molecular mechanics/generalized born surface area VSGB 2.0 method. Finally, a 15 ns MD simulation was done to confirm the stability of the 4DXD–ligand complex. On a wider scope, the prospect of present work provides insight in designing molecules with better selective FtsZ inhibitory potential.     

Ability of the Public to Recognize Dogs Considered to Be Dangerous under the Dangerous Dogs Act in the United Kingdom

Canine aggression came into the public eye in the United Kingdom in the late 1980s prompting enactment of the UK Dangerous Dogs Act , which prohibits four breeds or “types” of dogs. The act faced strong opposition surrounding correct identification of prohibited dogs. A questionnaire was distributed to the public via an online platform, especially targetting those who have worked with dogs. The questionnaire assessed respondents’ abilities to identify the four banned types of dogs from other breeds and their capability to identify Pit Bull Terrier types from other similar dog types. Identification of both banned breeds, F(1, 20) = 57.746, p < .001, and bull breeds, F(1, 20) = 9.293, p = .006, was significantly lower than identification of other breeds. Recognition of Pit Bull Terrier types from similar types of dogs was generally poor, although people in a dog-related profession, as opposed to those in other professions, could correctly distinguish more pit bull-type dogs (U = 46,164.0, n₁ = 187, n₂ = 575, p = .003). Findings suggest public understanding of dangerous dogs is poor, and it may impact societal perceptions of dogs more widely.     

Subcellular Localization and Kinetic Characterization of a Gill (Na+, K+)-ATPase from the Giant Freshwater Prawn Macrobrachium rosenbergii

The stimulation by Mg²⁺, Na⁺, K⁺, NH₄ ⁺, and ATP of (Na⁺, K⁺)-ATPase activity in a gill microsomal fraction from the freshwater prawn Macrobrachium rosenbergii was examined. Immunofluorescence labeling revealed that the (Na⁺, K⁺)-ATPase α-subunit is distributed predominantly within the intralamellar septum, while Western blotting revealed a single α-subunit isoform of about 108 kDa M _r. Under saturating Mg²⁺, Na⁺, and K⁺ concentrations, the enzyme hydrolyzed ATP, obeying cooperative kinetics with V _M = 115.0 ± 2.3 U mg^?1, K _0.5 = 0.10 ± 0.01 mmol L^?1. Stimulation by Na⁺ (V _M = 110.0 ± 3.3 U mg^?1, K _0.5 = 1.30 ± 0.03 mmol L^?1), Mg²⁺ (V _M = 115.0 ± 4.6 U mg^?1, K _0.5 = 0.96 ± 0.03 mmol L^?1), NH₄ ⁺ (V _M = 141.0 ± 5.6 U mg^?1, K _0.5 = 1.90 ± 0.04 mmol L^?1), and K⁺ (V _M = 120.0 ± 2.4 U mg^?1, K _M = 2.74 ± 0.08 mmol L^?1) followed single saturation curves and, except for K⁺, exhibited site–site interaction kinetics. Ouabain inhibited ATPase activity by around 73 % with K _I = 12.4 ± 1.3 mol L^?1. Complementary inhibition studies suggest the presence of F₀F₁–, Na⁺-, or K⁺-ATPases, but not V(H⁺)- or Ca²⁺-ATPases, in the gill microsomal preparation. K⁺ and NH₄ ⁺ synergistically stimulated enzyme activity (≈25 %), suggesting that these ions bind to different sites on the molecule. We propose a mechanism for the stimulation by both NH₄ ⁺, and K⁺ of the gill enzyme.     

Factors Affecting Distribution of Earthworms in Kashmir Valley: A Multivariate Statistical Approach

Soil characteristics influence earthworm population dynamics, species distribution and community structure. According in the present study an attempt was made to determine the soil physiochemical factors influencing earthworms of Kashmir valley with a view to improve the soil productivity by enhancing earthworm diversity under different pedoecosystems. Data collection on 15 soil parameters from 20 earthworm inhabiting sites revealed significant variation within and among the sites in soil temperature (F_{23, 19} = 148.83, 9.71; P < 0.05), moisture (F_{23, 19} = 16.91, 46.20; P < 0.05), pH (F₁₉ = 47.21; P < 0.05), electrical conductivity (F_{23, 19} = 11.67, 87.13; P < 0.05), sodium (F_{23, 19} = 2.46, 211.25; P < 0.05), potassium (F₁₉ = 22.91; P < 0.05), calcium (F₁₉ = 15.90; P < 0.05), magnesium (F_{23, 19} = 1.76, 104.51; P < 0.05), organic carbon (F_{23, 19} = 64.60, 222.50; P < 0.05), organic nitrogen (F_{23, 19} = 4.59, 3.81; P < 0.05) and phosphorous (F_{23, 19} = 5.11, 137.87; P < 0.05). Aporrectodea caliginosa trapezoides and A. rosea rosea exhibited wide range of distribution whereas Octolasion cyaneum, A. c. trapezoides and A. parva showed restricted distribution. Hierarchical cluster analysis grouped 20 earthworm collection sites into three clusters—earthworm absent sites, low earthworm diversity sites and moderate earthworm diversity sites. Principal component analysis assisted from the data set of 20 sites, resulting into four latent factors accounting for 77.95 % of total variance, identified the factors affecting earthworm communities are mainly related to physical habitat factor, chemical factor, soil texture factor and growth factor, each accounting for 26.41, 20.16, 18.25 and 13.13 % of total variance respectively.     

Poly –N = N– linked 1,5-dihydro-1,5-diazocine,the two-dimensional polymer with Dirac insulator properties: ab initio study

A new material – the monolayered, π-conjugated, poly dinitrogen-linked 1,5-dihydro-1,5-diazocine – is proposed. Density functional theory calculations reveal that the material is a two-dimensional Dirac insulator with a direct band gap. The generalised gradient approximation (GGA) and the local density approximation (LDA) give band gaps of E _gap ^GGA = 0.045 eV and E _gap ^LDA = 0.035 eV. Anisotropy of the Dirac cones results in variation of Fermi velocities of the charge carriers: [0.85–5.30] × 10⁶ m/s (GGA) and [0.86–5.38] × 10⁶ m/s (LDA). Corresponding effective masses are ～10³ lower than that of a free electron. G₀W₀ calculations confirm the topology of density functional theory band structure and show band gap of E _gap = 0.121 eV. Cohesive energies are estimated at E _c ^GGA = 5.30 eV/atom and E _c ^LDA = 6.15 eV/atom. Thus, the results provide the first evidence for the existence of Dirac insulators among organic polymers.     

Measurement of Cerebral Glucose Utilization Using Washout After Carotid Injection in the Rat

Abstract: The carotid injection technique, used previously to quantitate the kinetics of blood-brain barrier transport of metabolic substrates, may be modified to analyze the rate of cerebral glucose utilization. A 0.2-ml solution of [¹⁴C]glucose (G_F) and [³H]methylglucose (M), an internal reference, is rapidly injected into the carotid artery, followed by microwave fixation of brain at various times up to 4 min after injection. The brain radioactivity is separated into a fraction containing neutral hexoses (G_F and M) and a fraction containing metabolites of glucose. The G_F/M ratio is related to the rate constant (k₃) of brain glucose utilization by the simple, linear equation: In(G_F/M) = In(G_F°/M°) –k₃t, where G_F°/M°= the brain uptake index of glucose, relative to methylglucose, at 5-15 s after injection, and t= the time after carotid injection, e.g., 1–4 min. It is assumed that (a) the rate of influx due to recirculation of label is minimal during the 4-min circulation period; and (b) the rate constants of glucose efflux (k₂) and methylglucose efflux (k₂*) are identical. Independent estimates of k₂ and k₂* showed these parameters to be identical: k₂= 0.14 + 0.08 min-I; k₂*= 0.14 ± 0.02 min-I. A logarithmic plot of G_F/M ratios versus time was linear (r = 0.99), and was described by the slope k₂= 0.21 ± 0.02 min^?1. Assuming glucose is uniformly distributed in brain, then the glycolytic rate = k₃× brain glucose = (0.21 min^?1) (2.6 μmol g^?1) = 0.55 μmol min^?1 g^?1 for the cortex of the barbiturate-anesthetized rat. These studies provide the basis for a simple method of measurement of regional brain glycolysis that does not require either the use of correction factors, e.g., the lumped constant, or the use of differentially labeled glucose.