Flexible Function Research Articles

Weibull Regression and Stratified Cox Regression in Modelling Exclusive Breastfeeding Duration

Survival analysis has three approaches, parametric, non-parametric, and semi-parametric. The parametric model requires the distribution of survival time to be known. Weibull regression is one of the most popular forms of parametric approaches with advantages in flexibility and simplicity of hazard functions and survival functions. Stratified Cox regression is a semi-parametric approach method that is rightly used when the proportional hazard assumption is violated. The comparison between Weibull regression and stratified Cox regression was applied in the case of the duration of exclusive breastfeeding in infants aged 0-6 months in Indonesia. Before the model was formed, the data were tested for the Weibull distribution and the results were met properly. Whereas for testing proportional hazard assumptions the results are not fulfilled so that semi-parametric models can be used. Based on the results of the study, the Weibull regression is better than the stratified Cox regression.

MOLECULAR DOCKING: AN EXPLANATORY APPROACH IN STRUCTURE-BASED DRUG DESIGNING AND DISCOVERY

Molecular docking is a modeling tool of Bioinformatics which includes two or more molecules which interact to provide a stable product in the form of a complex. Molecular docking is helpful in predicting the 3-d structure of a complex which depends on the binding characteristics of Ligand and target. Also, it is a structure-based virtual screening (SBVS) utilized to keep the 3-d structures of small molecule which are generated by computers into a target structure in various types of conformations, positions and orientations. This molecular docking has come out to be a novel concept with various types of advantages. It behaves as a highly exploring domain due to its significant structure-based drug design (SBDD), Assessment of Biochemical pathways, Lead Optimization and in De Novo drug design. In spite of all potential approaches, there are certain challenges which are-scoring function (differentiate the true binding mode), ligand chemistry (tautomerism and ionization) and receptor flexibility (single conformation of rigid receptor). The area of computer-aided drug design and discovery (CADDD) has achieved large favorable outcomes in the past few years. CADD has been adopted by various big pharmaceutical companies for leading discoveries of drugs. Many researchers have worked in order to examine different docking algorithms and to predict molecules' active site. Hence, this Review article depicts the whole sole of Molecular Docking.

Intercooperation, flexicurity and their impact on workers: The case of Fagor Electrodomésticos

AbstractMondragon cooperatives have used flexible employment, training and labour protection policies to deal with economic crises since the 1970s. These policies were also used in 2013 to alleviate the social consequences of the demise of their biggest industrial cooperative, Fagor Electrodomésticos. This article aims to analyze—through 40 interviews with different stakeholders—the advantages and limitations of wage, working time and functional flexibility policies by framing them under the flexicurity concept. In contrast with previous research on Mondragon cooperatives, this study has found a strong worker‐owner resistance to flexicurity policies, mainly before the firm's bankruptcy. The study has also found the main reasons for worker resistance and for some successful Mondragon cooperatives’ reluctance to offer permanent relocations to redundant Fagor Electrodomésticos’ members. This research will help cooperatives to maintain and improve their flexicurity policies and their resilience. Some findings can be extrapolated to the growing number of firms that aim to implement flexicurity policies without harming their workers’ social welfare.

Examining the Impact of a Mobile Health App on Functional Movement and Physical Fitness: Pilot Pragmatic Randomized Controlled Trial.

BackgroundNumerous mobile apps available for download are geared toward health and fitness; however, limited research has evaluated the real-world effectiveness of such apps. The movr app is a mobile health app designed to enhance physical functioning by prescribing functional movement training based on individualized movement assessments. The influence of the movr app on functional movement and physical fitness (flexibility, strength, and cardiovascular fitness) has not yet been established empirically.ObjectiveThis study aims to examine the real-world impact of the movr app on functional movement, flexibility, strength, and cardiovascular fitness.MethodsA total of 48 healthy adults (24 women and 24 men; mean age 24, SD 5 years) completed an 8-week pilot pragmatic randomized controlled trial in which they were randomly assigned to either 8-week use of the movr app (n=24) or 8-week waitlist control (n=24). Measures of functional movement (Functional Movement Screen [FMS]), strength (push-ups, handgrip strength, and countermovement jump), flexibility (shoulder flexibility, sit and reach, active straight leg raise [ASLR], and half-kneeling dorsiflexion), and cardiovascular fitness (maximal oxygen uptake []) were collected at baseline and the 8-week follow-up.ResultsRepeated measures analyses of variance revealed significant group-by-time interactions for the 100-point FMS (P<.001), shoulder flexibility (P=.01), ASLR (P=.001), half-kneeling dorsiflexion (P<.001), and push-up tests (P=.03). Pairwise comparisons showed that FMS scores increased from pre- to postintervention for those in the movr group (P<.001) and significantly decreased for those in the control group (P=.04). For shoulder flexibility, ASLR, half-kneeling dorsiflexion, and push-up tests, improvements from pre- to postintervention were found in the movr group (all values of P<.05) but not in the control group (all values of P>.05). There were no changes in the sit and reach or handgrip strength test scores for either group (all values of P>.05). A significant main effect of time was found for the countermovement jump (P=.02), such that scores decreased from pre- to postintervention in the control group (P=.02) but not in the movr group (P=.38). Finally, a significant group-by-time interaction was found for (P=.001), revealing that scores decreased pre- to postintervention in the control group (P<.001), but not in the movr group (P=.54).ConclusionsThe findings revealed that movr improved indices of functional movement (FMS), flexibility (shoulder, ASLR, and dorsiflexion), and muscular endurance (push-ups) over an 8-week period compared with the control group while maintaining handgrip strength, lower body power (countermovement jump), and cardiovascular fitness (). Thus, this study provides initial evidence of the effectiveness of the movr app for enhancing functional movement and physical fitness among healthy adults.Trial RegistrationClinicalTrials.gov NCT04865666; https://clinicaltrials.gov/ct2/show/NCT04865666

Dissociable plasticity of visual-motor system in functional specialization and flexibility in expert table tennis players.

Specialization and flexibility are two basic attributes of functional brain organization, enabling efficient cognition and behavior. However, it is largely unknown what plastic changes in specialization and flexibility in visual-motor areas occur in support of extraordinary motor skills in expert athletes and how the selective adaptability of the visual-motor system affects general perceptual or cognitive domains. Here, we used a dynamic network framework to investigate intrinsic functional specialization and flexibility of visual-motor system in expert table tennis players (TTP). Our results showed that sensorimotor areas increased intrinsic functional flexibility, whereas visual areas increased intrinsic functional specialization in expert TTP compared to nonathletes. Moreover, the flexibility of the left putamen was positively correlated with skill level, and that of the left lingual gyrus was positively correlated with behavioral accuracy of a sport-unrelated attention task. This study has uncovered dissociable plasticity of the visual-motor system and their predictions of individual differences in skill level and general attention processing. Furthermore, our time-resolved analytic approach is applicable across other professional athletes for understanding their brain plasticity and superior behavior.

Viewing SARS-CoV-2 Nucleocapsid Protein in Terms of Molecular Flexibility.

Simple SummaryNucleocapsid protein is one of the essential proteins for viral replication including the coronavirus SARS-CoV-2, which causes coronavirus disease 2019 (COVID-19) pneumonia leading to the ongoing pandemic. Whereas this protein has emerged as a potential drug target, its physicochemical properties and the molecular mechanism of how this protein is involved in viral replication remain unclear. In this review, structural and dynamical aspects of the SARS-CoV-2 nucleocapsid protein (NCoV2), which should play a key role in a new drug development and in the interaction with RNA and other proteins are summarized. The structural feature of NCoV2 is first described. Next, simulation studies on the interaction between potential drug molecules and NCoV2 are summarized, which show the importance of molecular flexibility. Then, liquid-liquid phase separation phenomenon involving NCoV2, which has recently been reported, is described. This phenomenon also suggests the importance of molecular flexibility of NCoV2. Finally, a promising method using neutron scattering to characterize the structure and structural fluctuation of the droplets, which are formed through this phenomenon, is presented.The latest coronavirus SARS-CoV-2, which causes coronavirus disease 2019 (COVID-19) pneumonia leading to the pandemic, contains 29 proteins. Among them, nucleocapsid protein (NCoV2) is one of the abundant proteins and shows multiple functions including packaging the RNA genome during the infection cycle. It has also emerged as a potential drug target. In this review, the current status of the research of NCoV2 is described in terms of molecular structure and dynamics. NCoV2 consists of two domains, i.e., the N-terminal domain (NTD) and the C-terminal domain (CTD) with a disordered region between them. Recent simulation studies have identified several potential drugs that can bind to NTD or CTD with high affinity. Moreover, it was shown that the degree of flexibility in the disordered region has a large effect on drug binding rate, suggesting the importance of molecular flexibility for the NCoV2 function. Molecular flexibility has also been shown to be integral to the formation of droplets, where NCoV2, RNA and/or other viral proteins gather through liquid-liquid phase separation and considered important for viral replication. Finally, as one of the future research directions, a strategy for obtaining the structural and dynamical information on the proteins contained in droplets is presented.

Sensory, somatomotor and internal mentation networks emerge dynamically in the resting brain with internal mentation predominating in older age

Age-related changes in the brain are associated with a decline in functional flexibility. Intrinsic functional flexibility is evident in the brain's dynamic ability to switch between alternative spatiotemporal states during resting state. However, the relationship between brain connectivity states, associated psychological functions during resting state, and the changes in normal aging remain poorly understood. In this study, we analyzed resting-state functional magnetic resonance imaging (rsfMRI) data from the Human Connectome Project (HCP; N = 812) and the UK Biobank (UKB; N = 6,716). Using signed community clustering to identify distinct states of dynamic functional connectivity, and text-mining of a large existing literature for functional annotation of each state, our findings from the HCP dataset indicated that the resting brain spontaneously transitions between three functionally specialized states: sensory, somatomotor, and internal mentation networks. The occurrence, transition-rate, and persistence-time parameters for each state were correlated with behavioural scores using canonical correlation analysis. We estimated the same brain states and parameters in the UKB dataset, subdivided into three distinct age ranges: 50–55, 56–67, and 68–78 years. We found that the internal mentation network was more frequently expressed in people aged 71 and older, whereas people younger than 55 more frequently expressed sensory and somatomotor networks. Furthermore, analysis of the functional entropy — a measure of uncertainty of functional connectivity — also supported this finding across the three age ranges. Our study demonstrates that dynamic functional connectivity analysis can expose the time-varying patterns of transition between functionally specialized brain states, which are strongly tied to increasing age.

Sexual dimorphism in adipose tissue mitochondrial function and metabolic flexibility in obesity

ObjectiveThe prevalence of obesity is growing globally. Adiposity increases the risk for metabolic syndrome, type 2 diabetes and cardiovascular disease. Adipose tissue distribution influences systemic metabolism and impacts metabolic disease risk. The link between sexual dimorphisms of adiposity and metabolism is poorly defined. We hypothesise that depot-specific adipose tissue mitochondrial function contributes to the sexual dimorphism of metabolic flexibility in obesity.MethodsMale and female mice fed high fat diet (HFD) or standard diet (STD) from 8–18 weeks of age underwent whole animal calorimetry and high-resolution mitochondrial respirometry analysis on adipose tissue depots. To determine translatability we used RT-qPCR to examine key brown adipocyte-associated gene expression: peroxisome proliferator-activated receptor co-activator 1α, Uncoupling protein 1 and cell death inducing DFFA like effector a in brown adipose tissue (BAT) and subcutaneous adipose tissue (sWAT) of 18-week-old mice and sWAT from human volunteers.ResultsMale mice exhibited greater weight gain compared to female mice when challenged with HFD. Relative to increased body mass, the adipose to body weight ratio for BAT and sWAT depots was increased in HFD-fed males compared to female HFD-fed mice. Oxygen consumption, energy expenditure, respiratory exchange ratio and food consumption did not differ between males and females fed HFD. BAT mitochondria from obese females showed increased Complex I & II respiration and maximal respiration compared to lean females whereas obese males did not exhibit adaptive mitochondrial BAT respiration. Sexual dimorphism in BAT-associated gene expression in sWAT was also associated with Body Mass Index in humans.ConclusionsWe show that sexual dimorphism of weight gain is reflected in mitochondrial respiration analysis. Female mice have increased metabolic flexibility to adapt to changes in energy intake by regulating energy expenditure through increased complex II and maximal mitochondrial respiration within BAT when HFD challenged and increased proton leak in sWAT mitochondria.

Testing the Disgust-Based Mechanism of Homonegative Attitudes in the Context of the COVID-19 Pandemic.

Negative attitudes and stigmatization can originate from the perception of a disease-related threat. Following the spread of the COVID-19 pandemic, it is often suggested that incidents of discriminatory behavior are the result of defense mechanisms aimed at avoiding pathogens. According to the behavioral immune system theory, people are motivated to distance themselves from individuals who show signs of infection, or who are only heuristically associated with a disease, primarily because of the disgust they evoke. In this paper we focus on negative attitudes toward gay men and lesbians who are among social groups that have been persistently framed as “unclean.” In our correlational study (N = 500 heterosexual participants; Polish sample data collected during the first COVID-19 lockdown in Poland, in March/April 2020) we tested moderation models derived from the behavioral immune system theory. Specifically, we investigated whether perceived vulnerability to disease and perceived threat of contracting COVID-19 moderate the relation between disgust and homonegativity. We found that sexual disgust (but not pathogen nor moral disgust) predicted homonegative attitudes. This effect was stronger for participants expressing higher levels of perceived vulnerability to disease but was not dependent on the perception of the COVID-19 threat. The results reaffirm previous evidence indicating a pivotal role of disgust in disease-avoidance mechanisms. They also point to functional flexibility of the behavioral immune system by demonstrating the moderating role of perceived vulnerability to disease in shaping homonegative attitudes. Finally, they show that the threat of COVID-19 does not strengthen the relationship between disgust and homonegativity.

An Elastic System Architecture for Edge Based Low Latency Interactive Video Applications

5G and edge computing have brought great changes to video industry. Interactive video is becoming an emerging application form of multimedia service, which provides attraction beyond typical scenarios like cloud gaming and remote virtual reality (VR), and puts forward great challenges in resource capacity, response latency, and function flexibility to its service system. In this paper, we propose an elastic system architecture with low latency features to accommodate generic interactive video applications on near user edges. To increase system flexibility, we firstly design a dynamic Directed Acyclic Graph (dDAG) model for efficient task representation. Secondly, based on the model, we present the elastic architecture together with its scalable workflow pipeline. Thirdly, we propose a set of novel latency measurement metrics to analyze and optimize the performance of an interactive video system. Based on the proposed approaches, we disassemble a real world free-viewpoint synthesis application and benchmark its performance with the metrics. Extensive experimental results show the flexibility of our system to handle the stochastic human interactions during a video service session, with less than 5 ms additional scheduling latency introduced. End to end latency is kept within 43 ms for complex functions, and 28 ms for simpler scenarios, which satisfies the restrictions of most interactive video applications provided by an edge. Client of the architecture serves as a pure video player, which is also friendly to power limited terminals such as 5G phones. Efficiency and stability analyses of the system show superiorities over existing work, and also reveal potential optimization directions for future research.

Formins

Actin is one of the most abundant proteins in eukaryotes. Discovered in muscle and described as far back as 1887, actin was first purified in 1942. It plays myriad roles in essentially every eukaryotic cell. Actin is central to development, muscle contraction, and cell motility, and it also functions in the nucleus, to name a spectrum of examples. The flexibility of actin function stems from two factors: firstly, it is dynamic, transitioning between monomer and filament, and, secondly, there are hundreds of actin-binding proteins that build and organize specific actin-based structures. Of prime importance are actin nucleators - proteins that stimulate de novo formation of actin filaments. There are three known classes of actin nucleators: the Arp2/3 complex, formins, and tandem WASP homology 2 (WH2) nucleators. Each class nucleates by a distinct mechanism that contributes to the organization of the larger structure being built. Evidence shows that the Arp2/3 complex produces branched actin filaments, remaining bound at the branch point, while formins create linear actin filaments, remaining bound at the growing end. Here, we focus on the formin family of actin nucleators.

Relationship between cognitive performance and social rank in male and female cynomolgus macaques: Implications for the role of cognition in vulnerability to cocaine use disorder

Cocaine use disorder (CUD) currently has no FDA-approved pharmacological treatment. One of the most promising behavioral interventions is cognitive behavioral therapy. Still, there is a continuing need to understanding what makes an individual susceptible to CUD. A major goal of this study is to determine if cognitive performance can serve as a behavioral biomarker related to vulnerability to cocaine abuse. Previous studies have shown sex differences in vulnerability to cocaine based on social rank (Morgan et al., 2002; Nader et al., 2012). The goal of the present study is to evaluate cognitive performance as a potential biomarker for vulnerability to cocaine abuse, in socially housed cocaine-naïve female and male monkeys. In an earlier study involving newly formed social groups of female monkeys, performance on one cognitive domain, working memory using a delayed-match-to-sample task, showed social rank differences only during establishment of the social hierarchy; once the hierarchies were stable, there were no differences in working memory across social ranks (Kromrey et al., 2016). The present study differs from our earlier work by studying several cognitive domains in well-established, same-sex, male and female social groups (N=8/sex). Monkeys were trained to complete a battery of cognitive tasks which evaluated learning and memory (stimulus discrimination; SD and compound discrimination; CD), executive function (reversal learning; SDR) and behavioral flexibility (interdimensional shifting; ID, extradimensional shifting; and reversal, ED, EDR). The test battery consisted of monkeys performing all tasks (SD/SDR, CD, ID, ED/EDR) in 1-3 sessions; criteria for moving to the next task was 12/15 trials correct. All studies were performed in accordance with the FASEB Statement of Principles for the Use of Vertebrate Animals in Research and Education and Wake Forest's IACUC. We hypothesized that because earlier work had shown subordinate males and dominant females were more vulnerable to cocaine reinforcement, that they would show poorer cognitive performance relative to dominant males and subordinate females. In preliminary findings, dominant male and female monkeys made fewer total errors and required less trials to complete the battery compared with subordinate animals, in contrast to our hypothesis. Next, acquisition of cocaine reinforcement will be examined in an effort to replicate earlier findings and then the test battery will be repeated at various timepoints in order to evaluate the effects of cocaine on cognitive performance as a function of sex and social rank.

Iterative Exponential Growth of Oxygen-Linked Aromatic Polymers Driven by Nucleophilic Aromatic Substitution Reactions.

This work presents the first transition metal-free synthesis of oxygen-linked aromatic polymers by integrating iterative exponential polymer growth (IEG) with nucleophilic aromatic substitution (SNAr) reactions. Our approach applies methyl sulfones as the leaving groups, which eliminate the need for a transition metal catalyst, while also providing flexibility in functionality and configuration of the building blocks used. As indicated by 1) 1H-1H NOESY NMR spectroscopy, 2) single-crystal X-ray crystallography, and 3) density functional theory (DFT) calculations, the unimolecular polymers obtained are folded by nonclassical hydrogen bonds formed between the oxygens of the electron-rich aromatic rings and the positively polarized C–H bonds of the electron-poor pyrimidine functions. Our results not only introduce a transition metal-free synthetic methodology to access precision polymers but also demonstrate how interactions between relatively small, neutral aromatic units in the polymers can be utilized as new supramolecular interaction pairs to control the folding of precision macromolecules.

Moving towards multi-layered, mixed-species forests in riparian buffers will enhance their long-term function in boreal landscapes

Riparian buffers are the primary tool in forest management for protecting the habitat structure and function of streams. They help protect against biogeochemical perturbation, filter sediments and nutrients, prevent erosion, contribute food to aquatic organisms, regulate light and hence water temperature, contribute deadwood, and preserve biodiversity. However, in production forests of Sweden and Finland, many headwater streams have been straightened, ditched, and/or channelized, resulting in altered hydrology and reduced natural disturbance by floods, which in turn affects important riparian functions. Furthermore, in even-aged management systems as practiced in much of Fennoscandia, understory trees have usually been cleared right up to the stream’s edge during thinning operations, especially around small, headwater streams. Fire suppression has further favored succession towards shade tolerant species. In the regions within Fennoscandia that have experienced this combination of intensive management and lack of natural disturbance, riparian zones are now dominated by single-storied, native Norway spruce. When the adjacent forest is cut, thin (5 - 15m) conifer-dominated riparian buffers are typically left. These buffers do not provide the protection and subsidies, in terms of leaf litter quality, needed to maintain water quality or support riparian or aquatic biodiversity. Based on a literature review, we found compelling evidence that the ecological benefits of multi-layered, mixed-species riparian forest with a large component of broadleaved species are higher than what is now commonly found in the managed stands of Fennoscandia. To improve the functionality of riparian zones, and hence the protection of streams in managed forest landscapes, we present some basic principles that could be used to enhance the ecological function of these interfaces. These management actions should be prioritized on streams and streamside stands that have been affected by simplification either through forest management or hydrological modification. Key to these principles is the planning and managing of buffer zones as early as possible in the rotation to ensure improved function throughout the rotation cycle and not only at final felling. This is well in line with EU and national legislation which can be interpreted as requiring landscape planning at all forest ages to meet biodiversity and other environmental goals. However, it is still rare that planning for conservation is done other than at the final felling stage. Implementing this new strategy is likely to have long-term positive effects and improve the protection of surface waters from negative forestry effects and a history of fire suppression. By following these suggested management principles, there will be a longer time period with high function and greater future management flexibility in addition to the benefits provided by leaving riparian buffers at the final felling stage.

Observing spontaneous, accelerated substrate binding in molecular dynamics simulations of glutamate transporters.

Glutamate transporters are essential for removing the neurotransmitter glutamate from the synaptic cleft. Glutamate transport across the membrane is associated with elevator-like structural changes of the transport domain. These structural changes require initial binding of the organic substrate to the transporter. Studying the binding pathway of ligands to their protein binding sites using molecular dynamics (MD) simulations requires micro-second level simulation times. Here, we used three methods to accelerate aspartate binding to the glutamate transporter homologue Gltph and to investigate the binding pathway. 1) Two methods using user-defined forces to prevent the substrate from diffusing too far from the binding site. 2) Conventional MD simulations using very high substrate concentrations in the 0.1 M range. The final, substrate bound states from these methods are comparable to the binding pose observed in crystallographic studies, although they show more flexibility in the side chain carboxylate function. We also captured an intermediate on the binding pathway, where conserved residues D390 and D394 stabilize the aspartate molecule. Finally, we investigated glutamate binding to the mammalian glutamate transporter, excitatory amino acid transporter 1 (EAAT1), for which a crystal structure is known, but not in the glutamate-bound state. Overall, the results obtained in this study reveal new insights into the pathway of substrate binding to glutamate transporters, highlighting intermediates on the binding pathway and flexible conformational states of the side chain, which most likely become locked in once the hairpin loop 2 closes to occlude the substrate.

Neuroplastic effects of a selective serotonin reuptake inhibitor in relearning and retrieval

Animal studies using selective serotonin reuptake inhibitors (SSRIs) and learning paradigms have demonstrated that serotonin is important for flexibility in executive functions and learning. SSRIs might facilitate relearning through neuroplastic processes and thus exert their clinical effects in psychiatric diseases where cognitive functioning is affected. However, translation of these mechanisms to humans is missing. In this randomized placebo-controlled trial, we assessed functional brain activation during learning and memory retrieval in healthy volunteers performing associative learning tasks aiming to translate facilitated relearning by SSRIs.To this extent, seventy-six participants underwent three MRI scanning sessions: (1) at baseline, (2) after three weeks of daily associative learning and subsequent retrieval (face-matching or Chinese character–noun matching) and (3) after three weeks of relearning under escitalopram (10 mg/day) or placebo. Associative learning and retrieval tasks were performed during each functional MRI (fMRI) session. Statistical modeling was done using a repeated-measures ANOVA, to test for content-by-treatment-by-time interaction effects.During the learning task, a significant substance-by-time interaction was found in the right insula showing a greater deactivation in the SSRI cohort after 21 days of relearning compared to the learning phase. In the retrieval task, there was a significant content-by-time interaction in the left angular gyrus (AG) with an increased activation in face-matching compared to Chinese-character matching for both learning and relearning phases. A further substance-by-time interaction was found in task performance after 21 days of relearning, indicating a greater decrease of performance in the placebo group.Our findings that escitalopram modulate insula activation demonstrates successful translation of relearning as a mechanism of SSRIs in human. Furthermore, we show that the left AG is an active component of correct memory retrieval, which coincides with previous literature. We extend the function of this region by demonstrating its activation is not only stimulus dependent but also time constrained. Finally, we were able to show that escitalopram aids in relearning, irrespective of content.

Associations between social burden, perceived stress, and diurnal cortisol profiles in older adults: implications for cognitive aging

Stress can be a risk factor for mental and physical health. We investigated the role of social burden as a potential stressor in older age and its associations with cognitive aging (i.e., within the domains inhibition and cognitive flexibility of executive functioning). Eighty-three older adults (N = 38 male, mean age = 74.0 ± 5.7 years, body-mass index = 25.5 ± 4.1 kg/m2) aged 64 years or older participated. Cognitive flexibility and inhibition were assessed by means of a Trail-Making Test (TMT) and a Stroop task. Perceived levels of social burden and perceived stress in general were assessed via standardized questionnaires. Furthermore, diurnal cortisol profiles were assessed. Overall, older participants showed lower cognitive performance than the younger (both inhibition and cognitive flexibility; p < .044). However, this association did not remain significant when adjusting for multiple comparisons. Social burden was highly correlated with perceived stress, highlighting its importance as a stressor (p < .001). Furthermore, participants who reported higher levels of perceived stress showed lower performance in the TMT as a measure for cognitive flexibility (p < .001). Moreover, social burden was associated with cognitive flexibility, which was assessed by means of the TMT (p = .031). However, this association did not remain significant when using the adjusted α-level. Furthermore, we found that total diurnal cortisol output was a mediator for the relationship between age and inhibition, which was assessed by means of a Stroop task. At last, we found that the mediating role of cortisol interacts with social burden in the way that especially in younger age, high levels of social burden are associated with higher cortisol levels and, therefore, with lower cognitive performance. We conclude that it is important to consider social burden as an additional stressor in older age which is associated with cognitive aging.

Human resources flexibility as a mediating mechanism between high-performance work systems and organizational performance: a multilevel quasi-longitudinal study

PurposeThe purpose of this study is to investigate the impact of high-performance work systems (HPWS) on organizational performance through the mediating role of human resources (HR) flexibility (expressed by functional flexibility, skills malleability and behavioural flexibility).Design/methodology/approachThe study examines theoretical relationships in the Greek context, which reflects changing economic and financial crisis, based on multilevel structural equation modelling estimation, using three waves of sample data collected in years 2014, 2016 and 2018 from organizations operating in the private sector.FindingsThe study finds that although HPWS positively influences all three HR flexibility dimensions, this positive effect is not transferred equally to organizational performance. The dominant effect on organizational performance is attributed to skills malleability, a smaller effect to behavioural flexibility and a negligible effect to functional flexibility.Research limitations/implicationsAlthough the data collected refer to three different years, most of the companies and individuals responded to sampling were different. As such, the study does not allow for dynamic causal inferences due to its quasi-longitudinal nature.Practical implicationsThe findings of this study may influence managerial decisions in developing bundles of HPWS policies and practices in relation to HR flexibility attributes.Originality/valueSince most studies consider HR flexibility as an aggregated construct, this study is possibly one of the very few studies that is examining the differential impact of the HR flexibility dimensions on organizational performance in turbulent times.

Curvature sensing amphipathic helix in the C-terminus of RTNLB13 is conserved in all endoplasmic reticulum shaping reticulons in Arabidopsis thaliana

The reticulon family of integral membrane proteins are conserved across all eukaryotes and typically localize to the endoplasmic reticulum (ER), where they are involved in generating highly-curved tubules. We recently demonstrated that Reticulon-like protein B13 (RTNLB13) from Arabidopsis thaliana contains a curvature-responsive amphipathic helix (APH) important for the proteins’ ability to induce curvature in the ER membrane, but incapable of generating curvature by itself. We suggested it acts as a feedback element, only folding/binding once a sufficient degree of curvature has been achieved, and stabilizes curvature without disrupting the bilayer. However, it remains unclear whether this is unique to RTNLB13 or is conserved across all reticulons—to date, experimental evidence has only been reported for two reticulons. Here we used biophysical methods to characterize a minimal library of putative APH peptides from across the 21 A. thaliana isoforms. We found that reticulons with the closest evolutionary relationship to RTNLB13 contain curvature-sensing APHs in the same location with sequence conservation. Our data reveal that a more distantly-related branch of reticulons developed a ~ 20-residue linker between the transmembrane domain and APH. This may facilitate functional flexibility as previous studies have linked these isoforms not only to ER remodeling but other cellular activities.

Multifunctional sensing activities toward heavy metals of three luminescent complexes: Effect of N-donor coligands and sensing medium

The functional groups and flexibility of organic building blocks were crucial for regulating the structure and luminescence as well as detecting activity of MOFs. Three Complexes of a flexible carboxylate ligand with –CH2-O- groups, namely, [Cd3(L)2(DMF)4]n (1), {[Cd3(L)2(bpea)3(H2O)4]∙2H2O∙4DMF}n (2), and [Cd3(L)2(bpy)]n (3) (H3L = 3,5-bis[(3-carboxyphenyl)oxy]benzoic acid, bpea = bis(pyridyl)ethane, and bpy = 4,4′-bipyridine), were synthesized under solventhermal conditions. Both complexes 1 and 2 exhibit interesting 2-D trilayer structures with (3,6)- and (3,4,6)-connected topology, respectively. Complex 3 displays 3-D complicated framework, in which Cd2+ ions are connected by the carboxylate groups of L3− ligands into 3-D motifs and further linked by bpy ligands. The flexible carboxylate ligand adopts three different coordination modes with the aromatic rings forming diverse dihedral angles. Luminescence measurements reveal that both the frameworks and the solvents play an important role on the sensing activities. Three complexes can selectively and sensitively detect Fe3+ and Cr2O72− in DMF through luminescence quenching (turn-off) with the latter two showing high water stability and sensing activities toward Fe3+ and Cr(VI) (Cr2O72− and CrO42−). The detection limits are in the range of 0.21–2.05 μM, comparable or superior to those of previous luminescence sensors. Specially, complex 3 could also detect Pb2+ in H2O with detection limit of 1.43 μM (0.30 ppm). The building units, the structures, the sensing media all have an effect on the sensing activities. Possible quenching mechanisms for detection of these ions were carefully investigated and proposed based on luminescence inner filter effect (IFE) and weak interactions between the target ions and frameworks. Moreover, the recoveries of 96.7–103.4% for the detection of above ions in tap water samples are achieved, suggesting practical application.