The ease with which we avoid falling down belies a highly sophisticated and distributed neural network for controlling reactions to maintain upright balance. Although historically these reactions ...were considered within the sub cortical domain, mounting evidence reveals a distributed network for postural control including a potentially important role for the cerebral cortex. Support for this cortical role comes from direct measurement associated with moments of induced instability as well as indirect links between cognitive task performance and balance recovery. The cerebral cortex appears to be directly involved in the control of rapid balance reactions but also setting the central nervous system in advance to optimize balance recovery reactions even when a future threat to stability is unexpected. In this review the growing body of evidence that now firmly supports a cortical role in the postural responses to externally induced perturbations is presented. Moreover, an updated framework is advanced to help understand how cortical contributions may influence our resistance to falls and on what timescale. The implications for future studies into the neural control of balance are discussed.
A
bstract
We make a comparative study of the neutrinoless double beta decay constraints on heavy sterile neutrinos versus other direct and indirect constraints from both lepton number conserving and ...violating processes, as a sensitive probe of the extent of lepton number violation and possible interference effects in the sterile sector. We introduce a phenomenological parametrisation of the simplified one-generation seesaw model with one active and two sterile neutrino states in terms of experimentally measurable quantities, such as active-sterile neutrino mixing angles, CP phases, masses and mass splittings. This simple parametrisation enables us to analytically derive a spectrum of possible scenarios between the canonical seesaw with purely Majorana heavy neutrinos and inverse seesaw with pseudo-Dirac ones. We then go on to constrain the simplified parameters of this model from various experiments at the energy, intensity and cosmic frontiers. We emphasise that the constraints from lepton number violating processes strongly depend on the mass splitting between the two sterile states and the relative CP phase between them. This is particularly relevant for neutrinoless double beta decay, which is weakened for small mass splitting and opposite CP parities between the sterile states. On the other hand, neutrinoless double beta decay is especially sensitive for Majorana sterile neutrinos with masses around 0
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1
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10 GeV.
AbstractAn analysis is presented of a database of 67 tests on 21 clays and silts of undrained shear stress-strain data of fine-grained soils. Normalizations of secant G in terms of initial mean ...effective stress p′ (i.e., G/p′ versus log γ) or undrained shear strength cu (i.e., G/cu versus log γ) are shown to be much less successful in reducing the scatter between different clays than the approach that uses the maximum shear modulus, Gmax, a technique still not universally adopted by geotechnical researchers and constitutive modelers. Analysis of semiempirical expressions for Gmax is presented and a simple expression that uses only a void-ratio function and a confining-stress function is proposed. This is shown to be superior to a Hardin-style equation, and the void ratio function is demonstrated as an alternative to an overconsolidation ratio (OCR) function. To derive correlations that offer reliable estimates of secant stiffness at any required magnitude of working strain, secant shear modulus G is normalized with respect to its small-strain value Gmax, and shear strain γ is normalized with respect to a reference strain γref at which this stiffness has halved. The data are corrected to two standard strain rates to reduce the discrepancy between data obtained from static and cyclic testing. The reference strain γref is approximated as a function of the plasticity index. A unique normalized shear modulus reduction curve in the shape of a modified hyperbola is fitted to all the available data up to shear strains of the order of 1%. As a result, good estimates can be made of the modulus reduction G/Gmax±30% across all strain levels in approximately 90% of the cases studied. New design charts are proposed to update the commonly used design curves.
Celotno besedilo
Dostopno za:
DOBA, FGGLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Deformations of sandy soils around geotechnical structures generally involve strains in the range small (0.01%) to medium (0.5%). In this strain range the soil exhibits non-linear stress-strain ...behaviour, which should be incorporated in any deformation analysis. In order to capture the possible variability in the non-linear behaviour of various sands, a database was constructed including the secant shear modulus degradation curves of 454 tests from the literature. By obtaining a unique S-shaped curve of shear modulus degradation, a modified hyperbolic relationship was fitted. The new empirical expression for shear modulus reduction G/G... is shown to make predictions that are accurate within a factor of 1.13 for one standard deviation of random error, as determined from 3860 data points. The new expressions for non-linear deformation are easy to apply in practice, and should be useful in the analysis of geotechnical structures under static loading.
Red Book Challenge Conservation Education Madagascar is a small‐scale, arts‐based, conservation education initiative founded in 2012 by two Lemur catta researchers working in the Berenty Reserve and ...incorporated as a nonprofit organization in 2022. The target demographic is children and adults living in Southern Madagascar. The Red Book Challenge program initially consisted of providing supplementary conservation education through classroom visits at the elementary schools in Berenty village. The school children created small conservation booklets with red covers, giving the project its name. Today, the program has expanded to include the village of Besakoa Ambany and the city of Fort Dauphin, while remaining a small‐scale program. To date, the Red Book Challenge has completed seven outreach projects aimed at generating goodwill in the local community, community development, and conservation education. This retrospective analysis functions as a formative evaluation of the feasibility of future projects. This paper will focus on four projects that fall under the category of conservation education: (1) Using films to promote conservation topics (2) field trips to observe lemurs (3) a Malagasy‐run conservation club, and (4) a coloring book. These projects have been funded through small grants from the International Conservation Fund of Canada, and private donations. This paper includes the Red Book Challenge's history, results from the participant surveys, and the successes and failures in each stage of our work. Six shifts in thinking occurred: (1) use of Malagasy talent to create educational conservation films (2) more formal assessment before and after field trips (3) improvement of recruitment, training and supervision of staff to keep the conservation club self‐sufficient (4) enlistment of Malagasy illustrators and adaptation of environmentally friendly printing practices for the coloring books (5) disseminate study outcomes to international community though publication (6) reframe the program from spare‐time volunteer work to full‐time research work.
Answers from all three sites to the question “Will you share what you have learned with your family?” as part of post‐field trip assessment
Research Highlights
Positive and negative results of our operation of a small primate conservation education program as secondary to our academic research are reported with the aim of encouraging primatologists to thoughtfully take up conservation education or make their current programs a priority.
Young people who participated in a field trip to see lemurs for the first time had their misconceptions about lemurs eliminated by the experience.
Of 70 school children in three locations in Southern Madagascar who received our coloring books, 84% stated that they were very likely to share what they had learned from the book with their family.
Sexual recombination drives genetic diversity in eukaryotic genomes and fosters adaptation to novel environmental challenges. Although strictly asexual microorganisms are often considered as ...evolutionary dead ends, they comprise many devastating plant pathogens. Presently, it remains unknown how such asexual pathogens generate the genetic variation that is required for quick adaptation and evolution in the arms race with their hosts. Here, we show that extensive chromosomal rearrangements in the strictly asexual plant pathogenic fungus Verticillium dahliae establish highly dynamic lineage-specific (LS) genomic regions that act as a source for genetic variation to mediate aggressiveness. We show that such LS regions are greatly enriched for in planta-expressed effector genes encoding secreted proteins that enable host colonization. The LS regions occur at the flanks of chromosomal breakpoints and are enriched for retrotransposons and other repetitive sequence elements. Our results suggest that asexual pathogens may evolve by prompting chromosomal rearrangements, enabling rapid development of novel effector genes. Likely, chromosomal reshuffling can act as a general mechanism for adaptation in asexually propagating organisms.
AIMS: The objectives of this study were the following: (i) to investigate if Campylobacter negative flocks at first thinning remain negative at second thinning; (ii) to determine if the caecal counts ...in birds infected during first thinning remain lower than in birds that were positive at first thinning; and (iii) to determine if reducing the time between first and second thinning to a maximum of 4 days would reduce both the incidence and prevalence of broiler caecal contamination. METHODS AND RESULTS: Twenty‐two flocks were tested at first and second thinning using ISO methodologies. Of the 14 that had a 4‐day duration between first and second thinning, nine flocks were Campylobacter negative at first thinning. By second thinning, all 14 flocks were positive and Campylobacter counts ranged from 5·5 to 6·6 log₁₀ CFU g⁻¹regardless of the status at first thinning. The other eight flocks were all Campylobacter positive at first thinning with counts ranging from 0·8 to 6·1 log₁₀ CFU g⁻¹which increased to 5·1 to 6·9 log₁₀ CFU g⁻¹by second thinning (3–10 days). PCR speciation and MLST genotyping suggested the majority of isolates were Camp. jejuni belonging to STs 257, 814, 6763 and 6764. CONCLUSIONS: It was concluded that; thinning introduces Campylobacter into broiler flocks; caecal counts in birds at second thinning are similar, regardless of flock status at first thinning and reducing the time between first and second thinning to a maximum of 4 days is not an effective control strategy. SIGNIFICANCE AND IMPACT OF THE STUDY: This study informs Campylobacter control strategy at primary production, suggesting all post‐first thinning broilers should be treated as ‘high risk’ regardless of Campylobacter status at first thinning or duration between first and second thinning.
The distinction between normality and psychopathology has long been subject to debate. DSM-III and DSM-IV provided a definition of mental disorder to help clinicians address this distinction. As part ...of the process of developing DSM-V, researchers have reviewed the concept of mental disorder and emphasized the need for additional work in this area. Here we review the DSM-IV definition of mental disorder and propose some changes. The approach taken here arguably takes a middle course through some of the relevant conceptual debates. We agree with the view that no definition perfectly specifies precise boundaries for the concept of mental/psychiatric disorder, but in line with a view that the nomenclature can improve over time, we aim here for a more scientifically valid and more clinically useful definition.
Aim
The aim of this study was to apply the most sensitive molecular techniques in combination with culture‐based methods to characterize broiler farms in terms of the timeline (‘appearance’ and ...‘pattern’) of Campylobacter contamination prior to and post detection in the birds.
Methods and Results
Faecal and environmental samples were collected from three broiler farms (two flocks per farm). Real‐time PCR was used to test for the presence of Campylobacter. Culture‐based methods (enrichment and direct plating) were also applied and isolates were subject to a range of confirmatory tests before speciation (multiplex PCR). All flocks were colonized by Campylobacter before first thin and a similar pattern of Campylobacter contamination was observed; (day −1) a range of external and internal samples real‐time PCR positive but culture negative; (day 0) chicks negative; (6–9 days pre‐detection in the birds) internal samples (feeders, drinkers, barrier and/or bird weigh) culture positive and (post broiler infection) increasing concentrations of Campylobacter in internal samples but also on the tarmac apron and anteroom.
Conclusion
It was concluded that; (i) vertical transmission did not occur; (ii) the environment was a potential source of Campylobacter; (iii) testing areas frequented by all birds (e.g. feeders and drinkers), may offer an opportunity for early Campylobacter detection and (iv) once the broilers are infected with Campylobacter, these bacteria are spread from the birds, through the anteroom to the areas surrounding the broiler house, highlighting the need for improved biosecurity.
Significance and Impact of the Study
This study has established the pattern of Campylobacter contamination on broiler farms, identified an early detection opportunity, highlighted the need to better understand the role of viable but nonculturable Campylobacter in the ecology of Campylobacter on broiler farms and demonstrated the need for improved biosecurity to prevent the spread of Campylobacter from within the house to the surrounding environment.
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