A Perspective is presented on the history and current understanding of molecular gels and the factors that must be considered to characterize them. The abilities of the most important structural, ...dynamic, and rheological tools available currently to provide the information necessary to follow the formation of a molecular gel from its initial sol phase and then to define it at different distance and time scales are discussed. Approaches to determining a priori when a molecule will gelate a selected liquid, as well as possible methodologies for overcoming current limitations in understanding molecular gels, are presented. Finally, some of the many potential and realized applications for these materials are enumerated.
Human coronaviruses (HCoVs) have been considered to be relatively harmless respiratory pathogens in the past. However, after the outbreak of the severe acute respiratory syndrome (SARS) and emergence ...of the Middle East respiratory syndrome (MERS), HCoVs have received worldwide attention as important pathogens in respiratory tract infection. This review focuses on the epidemiology, pathogenesis and clinical characteristics among SARS-coronaviruses (CoV), MERS-CoV and other HCoV infections.
Demonstrations that grip strength has predictive power in relation to a range of health conditions—even when these are assessed decades later—has motivated claims that hand-grip dynamometry has the ...potential to serve as a “vital sign” for middle-aged and older adults. Central to this belief has been the assumption that grip strength is a simple measure of physical performance that provides a marker of muscle status in general, and sarcopenia in particular. It is now evident that while differences in grip strength between individuals are influenced by musculoskeletal factors, “lifespan” changes in grip strength within individuals are exquisitely sensitive to integrity of neural systems that mediate the control of coordinated movement. The close and pervasive relationships between age-related declines in maximum grip strength and expressions of cognitive dysfunction can therefore be understood in terms of the convergent functional and structural mediation of cognitive and motor processes by the human brain. In the context of aging, maximum grip strength is a discriminating measure of neurological function and brain health.
Key message
The number of SNPs required for QTL discovery is justified by the distance at which linkage disequilibrium has decayed. Simulations and real potato SNP data showed how to estimate and ...interpret LD decay.
The magnitude of linkage disequilibrium (LD) and its decay with genetic distance determine the resolution of association mapping, and are useful for assessing the desired numbers of SNPs on arrays. To study LD and LD decay in tetraploid potato, we simulated autotetraploid genotypes and used it to explore the dependence on: (1) the number of haplotypes in the population (the amount of genetic variation) and (2) the percentage of haplotype specific SNPs (hs-SNPs). Several estimators for short-range LD were explored, such as the average
r
2
, median
r
2
, and other percentiles of
r
2
(80, 90, and 95 %). For LD decay, we looked at LD
½,90
, the distance at which the short-range LD is halved when using the 90 % percentile of
r
2
at short range, as estimator for LD. Simulations showed that the performance of various estimators for LD decay strongly depended on the number of haplotypes, although the real value of LD decay was not influenced very much by this number. The estimator LD
½,90
was chosen to evaluate LD decay in 537 tetraploid varieties. LD
½,90
values were 1.5 Mb for varieties released before 1945 and 0.6 Mb in varieties released after 2005. LD
½,90
values within three different subpopulations ranged from 0.7 to 0.9 Mb. LD
½,90
was 2.5 Mb for introgressed regions, indicating large haplotype blocks. In pericentromeric heterochromatin, LD decay was negligible. This study demonstrates that several related factors influencing LD decay could be disentangled, that no universal approach can be suggested, and that the estimation of LD decay has to be performed with great care and knowledge of the sampled material.
‘Inter‐hemispheric inhibition’ is used frequently to describe the action of one hemisphere in suppressing or impeding processing in its counterpart. It is widely believed that this is required in ...order to prevent a bilateral cerebrum giving rise to simultaneous and potentially competing outputs. It is argued here that a fundamental role of inter‐hemispheric inhibition is to support contrast enhancing and integrative functions by co‐opting the capacities of the two cerebral hemispheres. Drawing upon an extensive body of empirical data, derived largely from animal models, and associated theoretical modelling, it is demonstrated that inter‐hemispheric projections act via mechanisms such as surround/lateral inhibition. The principal functional unit of callosal influence comprises a facilitatory centre and a depressing peripheral zone, which together shape the influence of converging inputs to pyramidal neurons. Inter‐hemispheric inhibition is an instance of a more general feature of mammalian neural systems, whereby inhibitory interneurons act not simply to prevent over‐excitation but to sculpt the output of specific circuits. The narrowing of the excitatory focus that occurs through crossed surround inhibition is a highly conserved motif of transcallosal interactions in mammalian sensory and motor cortices. A case is presented that the ‘inter‐hemispheric competition’ model has been sustained, and its clinical derivatives promoted, by erroneous assumptions concerning that revealed by investigative techniques such as transcranial magnetic stimulation (TMS). The alternative perspective offered here is also shown to be consistent with known associations between the structural integrity of callosal projections and the magnitude of the motor deficits that are exhibited following stroke.
figure legend The principal functional unit of callosal influence comprises a facilitatory centre and a depressing peripheral zone, that together shape the influence of converging inputs to pyramidal neurons. This organization serves to sculpt and focus the output of neural circuits. In this schematic representation, cells that generate excitatory postsynaptic potentials (EPSPs) are represented in black. Callosal projections (excitatory) are represented in cyan. Inhibitory interneurons are represented in red. An inhibitory influence upon pyramidal tract cells in the surround region of the opposite hemisphere may arise from either local feed‐forward inhibitory circuits or recurrent inhibitory circuits. Although the patterns of inhibition elicited by callosal projections are in part an emergent property of these local networks, the actuating excitatory drive (from the opposite hemisphere) is necessarily also selective and highly differentiated. A key assumption is that such inter‐hemispheric interactions are reciprocal, and thus integrative. Figure redrawn and adapted from the author's original artwork, which is available at: https://commons.wikimedia.org/wiki/File:Functional_unit_of_callosal_influence.jpg. The original artwork contains elements derived from the following sources: https://upload.wikimedia.org/wikipedia/commons/f/f3/Muscle_fascicles_and_cells.png; https://commons.wikimedia.org/wiki/File:Corpus_callosum.gif. All of the artwork was published under either a Creative Commons Attribution‐Share Alike license or a Creative Commons CC0 Universal Public Domain Dedication.
Tuberculosis (TB) case notification rates are usually higher in men than in women, but notification data are insufficient to measure sex differences in disease burden. This review set out to ...systematically investigate whether sex ratios in case notifications reflect differences in disease prevalence and to identify gaps in access to and/or utilisation of diagnostic services.
In accordance with the published protocol (CRD42015022163), TB prevalence surveys in nationally representative and sub-national adult populations (age ≥ 15 y) in low- and middle-income countries published between 1 January 1993 and 15 March 2016 were identified through searches of PubMed, Embase, Global Health, and the Cochrane Database of Systematic Reviews; review of abstracts; and correspondence with the World Health Organization. Random-effects meta-analyses examined male-to-female (M:F) ratios in TB prevalence and prevalence-to-notification (P:N) ratios for smear-positive TB. Meta-regression was done to identify factors associated with higher M:F ratios in prevalence and higher P:N ratios. Eighty-three publications describing 88 surveys with over 3.1 million participants in 28 countries were identified (36 surveys in Africa, three in the Americas, four in the Eastern Mediterranean, 28 in South-East Asia and 17 in the Western Pacific). Fifty-six surveys reported in 53 publications were included in quantitative analyses. Overall random-effects weighted M:F prevalence ratios were 2.21 (95% CI 1.92-2.54; 56 surveys) for bacteriologically positive TB and 2.51 (95% CI 2.07-3.04; 40 surveys) for smear-positive TB. M:F prevalence ratios were highest in South-East Asia and in surveys that did not require self-report of signs/symptoms in initial screening procedures. The summary random-effects weighted M:F ratio for P:N ratios was 1.55 (95% CI 1.25-1.91; 34 surveys). We intended to stratify the analyses by age, HIV status, and rural or urban setting; however, few studies reported such data.
TB prevalence is significantly higher among men than women in low- and middle-income countries, with strong evidence that men are disadvantaged in seeking and/or accessing TB care in many settings. Global strategies and national TB programmes should recognise men as an underserved high-risk group and improve men's access to diagnostic and screening services to reduce the overall burden of TB more effectively and ensure gender equity in TB care.
Social anxiety disorder (SAD) and major depressive disorder (MDD) are highly comorbid, and together they result in greater functional impairment and a poorer prognosis than either condition alone. ...Theoretical models implicate impairments in emotion regulation in the development and maintenance of internalizing disorders, yet there has been no systematic comparison of emotion regulation in social anxiety and depression. The current review presents an in-depth examination of the literature on two widely-studied emotion regulation strategies, expressive suppression (ES) and cognitive reappraisal (CR), in SAD and MDD. Our review indicated that SAD is broadly characterized by an overreliance on ES, which is associated with negative social and emotional consequences. SAD is also characterized by ineffective utilization of CR, which inhibits the potential positive emotional benefits of this adaptive emotion regulation strategy. In contrast, MDD is broadly characterized by an underutilization of CR, which may be particularly detrimental in stressful or uncontrollable situations. For both SAD and MDD, treatment intervention appears to address deficits in CR but not ES. After reviewing the literature, we propose multiple pathways by which impairments in ES and CR may increase risk for the co-occurrence of SAD and MDD. Clinical implications and future research directions are also discussed.
•Social anxiety is characterized by an overreliance on expressive suppression.•Social anxiety is also connected to ineffective use of cognitive reappraisal.•Evidence is mixed regarding the role of expressive suppression in depression.•Depression is strongly associated with an underutilization of cognitive reappraisal.•Emotion regulation may play a role in co-occurring social anxiety and depression.
Summary
1. The R package ‘diversitree’ contains a number of classical and contemporary comparative phylogenetic methods. Key included methods are BiSSE (binary state speciation and extinction), MuSSE ...(a multistate extension of BiSSE), and QuaSSE (quantitative state speciation and extinction). Diversitree also includes methods for analysing trait evolution and estimating speciation/extinction rates independently.
2. In this note, I describe the features and demonstrate use of the package, using a new method, MuSSE (multistate speciation and extinction), to examine the joint effects of two traits on speciation.
3. Using simulations, I found that MuSSE could reliably detect that a binary trait that affected speciation rates when simultaneously accounting for additional thats that had no effect on speciation rates.
4. Diversitree is an open source and available on the Comprehensive R Archive Network (cran). A tutorial and worked examples can be downloaded from http://www.zoology.ubc.ca/prog/diversitree.
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