The International Physical Activity Questionnaire-Short Form (IPAQ-SF) has been recommended as a cost-effective method to assess physical activity. Several studies validating the IPAQ-SF have been ...conducted with differing results, but no systematic review of these studies has been reported.
The keywords "IPAQ", "validation", and "validity" were searched in PubMed and Scopus. Studies published in English that validated the IPAQ-SF against an objective physical activity measuring device, doubly labeled water, or an objective fitness measure were included.
Twenty-three validation studies were included in this review. There was a great deal of variability in the methods used across studies, but the results were largely similar. Correlations between the total physical activity level measured by the IPAQ-SF and objective standards ranged from 0.09 to 0.39; none reached the minimal acceptable standard in the literature (0.50 for objective activity measuring devices, 0.40 for fitness measures). Correlations between sections of the IPAQ-SF for vigorous activity or moderate activity level/walking and an objective standard showed even greater variability (-0.18 to 0.76), yet several reached the minimal acceptable standard. Only six studies provided comparisons between physical activity levels derived from the IPAQ-SF and those obtained from objective criterion. In most studies the IPAQ-SF overestimated physical activity level by 36 to 173 percent; one study underestimated by 28 percent.
The correlation between the IPAQ-SF and objective measures of activity or fitness in the large majority of studies was lower than the acceptable standard. Furthermore, the IPAQ-SF typically overestimated physical activity as measured by objective criterion by an average of 84 percent. Hence, the evidence to support the use of the IPAQ-SF as an indicator of relative or absolute physical activity is weak.
This paper presents the stability analysis of polynomial fuzzy-model-based (PFMB) control systems using the sum-of-squares (SOS) approach. The PFMB control system under consideration requires that ...the polynomial fuzzy model and polynomial fuzzy controller share neither the same premise membership functions nor the same number of fuzzy rules. This class of PFMB control systems offers a greater design flexibility to the polynomial fuzzy controller. However, due to the imperfectly matched membership functions, it usually produces more conservative stability conditions by following the traditional stability-analysis approach for the FMB control systems. To facilitate the stability analysis, piecewise-linear membership functions (PLMFs) are proposed, which offer a nice property that the grades of membership are governed by a finite number of sample points. Thus, it allows the PLMFs to be brought to the SOS-based stability conditions, which are applied to the PFMB control systems with the specified PLMFs rather than any shapes. The system stability can be examined by checking only the PFMB control system at the sample points. It is worth mentioning that the PLMFs, which are not necessarily implemented physically, are a mathematical tool to carry out the stability analysis. To verify the stability-analysis result, a simulation example is given to demonstrate the effectiveness of the proposed approach.
The Omicron variant is rapidly becoming the dominant SARS-CoV-2 virus circulating globally. It is important to define reductions in virus neutralizing activity in the serum of convalescent or ...vaccinated individuals to understand potential loss of protection against infection by Omicron. We previously established that a 50% plaque reduction neutralization antibody titer (PRNT
) ≥25.6 in our live virus assay corresponded to the threshold for 50% protection from infection against wild-type (WT) SARS-CoV-2. Here we show markedly reduced serum antibody titers against the Omicron variant (geometric mean titer (GMT) < 10) compared to WT virus 3-5 weeks after two doses of BNT162b2 (GMT = 218.8) or CoronaVac vaccine (GMT = 32.5). A BNT162b2 booster dose elicited Omicron PRNT
titers ≥25.6 in 88% of individuals (22 of 25) who previously received 2 doses of BNT162b2 and 80% of individuals (24 of 30) who previously received CoronaVac. However, few (3%) previously infected individuals (1 of 30) or those vaccinated with three doses of CoronaVac (1 of 30) met this threshold. Our findings suggest that countries primarily using CoronaVac vaccines should consider messenger RNA vaccine boosters in response to the spread of Omicron. Studies evaluating the effectiveness of different vaccines against the Omicron variant are urgently needed.
Summary Background Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality in China, where the population is also exposed to high levels of passive smoking, yet little ...information exists on the effects of such exposure on COPD. We examined the relation between passive smoking and COPD and respiratory symptoms in an adult Chinese population. Methods We used baseline data from the Guangzhou Biobank Cohort Study. Of 20 430 men and women over the age of 50 recruited in 2003–06, 15 379 never smokers (6497 with valid spirometry) were included in this cross-sectional analysis. We measured passive smoking exposure at home and work by two self-reported measures (density and duration of exposure). Diagnosis of COPD was based on spirometry and defined according to the GOLD guidelines. Findings There was an association between risk of COPD and self-reported exposure to passive smoking at home and work (adjusted odds ratio 1·48, 95% CI 1·18–1·85 for high level exposure; equivalent to 40 h a week for more than 5 years). There were significant associations between reported respiratory symptoms and increasing passive smoking exposure (1·16, 1·07–1·25 for any symptom). Interpretation Exposure to passive smoking is associated with an increased prevalence of COPD and respiratory symptoms. If this association is causal, we estimate that 1·9 million excess deaths from COPD among never smokers could be attributable to passive smoking in the current population in China. Our findings provide strong evidence for urgent measures against passive smoking in China.
•To reflect the environmental sensitivity of Vehicle Routing Problem (VRP).•To review the studies on VRP in energy consumption, emissions, reverse logistics.•To identify Green Vehicle Routing Problem ...(GVRP) and its classification.•To suggest the future research directions in GVRP.
Green Logistics has emerged as the new agenda item in supply chain management. The traditional objective of distribution management has been upgraded to minimizing system-wide costs related to economic and environmental issues. Reflecting the environmental sensitivity of vehicle routing problems (VRP), an extensive literature review of Green Vehicle Routing Problems (GVRP) is presented. We provide a classification of GVRP that categorizes GVRP into Green-VRP, Pollution Routing Problem, VRP in Reverse Logistics, and suggest research gaps between its state and richer models describing the complexity in real-world cases. The purpose is to review the most up-to-date state-of-the-art of GVRP, discuss how the traditional VRP variants can interact with GVRP and offer an insight into the next wave of research into GVRP. It is hoped that OR/MS researchers together with logistics practitioners can be inspired and cooperate to contribute to a sustainable industry.
This paper investigates the stability of fuzzy-model-based (FMB) control systems. An alternative stability-analysis approach using an artificial fuzzy system based on the Lyapunov stability theory is ...proposed. To facilitate the stability analysis, the continuous membership functions of the Takagi-Sugeno (T-S) fuzzy model are represented by the staircase ones. With the nice property of the staircase membership functions, it turns the set of infinite number of linear-matrix-inequality (LMI) based stability conditions into a finite one. Furthermore, the staircase membership functions carrying system information can be brought to the stability conditions to relax the stability conditions. The stability of the original FMB control systems is guaranteed by the satisfaction of the LMI-based stability conditions. The proposed stability analysis is applied to the FMB control systems of which the T-S fuzzy model and fuzzy controller do not share the same premise membership functions and, thus, is able to enhance the design flexibility of the fuzzy controller. A simulation example is given to illustrate the merits of the proposed approach.
Antimicrobial resistance remains a serious problem that results in high mortality and increased healthcare costs globally. One of the major issues is that resistant pathogens decrease the efficacy of ...conventional antimicrobials. Accordingly, development of novel antimicrobial agents and therapeutic strategies is urgently needed to overcome the challenge of antimicrobial resistance. A potential strategy is to kill pathogenic microorganisms via the formation of reactive oxygen species (ROS). ROS are defined as a number of highly reactive molecules that comprise molecular oxygen (O2), superoxide anion (O2•−), hydrogen peroxide (H2O2) and hydroxyl radicals (•OH). ROS exhibit antimicrobial actions against a broad range of pathogens through the induction of oxidative stress, which is an imbalance between ROS and the ability of the antioxidant defence system to detoxify ROS. ROS-dependent oxidative stress can damage cellular macromolecules, including DNA, lipids and proteins. This article reviews the antimicrobial action of ROS, challenges to ROS hypothesis, work to solidify ROS-mediated antimicrobial lethality hypothesis, recent developments in antimicrobial agents using ROS as an antimicrobial strategy, safety concerns related to ROS, and future directions in ROS research.
•Reactive oxygen species (ROS) could combat antimicrobial resistance.•ROS are used as an antimicrobial strategy because of their toxicity to a broad range of microbial pathogens.•ROS exert antimicrobial activity via an induction of oxidative stress in microbial cells.•Oxidative stress caused by ROS leads to microbial DNA damage, and ultimately inducing cell death.
Aims/hypothesis
Intra-islet and gut–islet crosstalk are critical in orchestrating basal and postprandial metabolism. The aim of this study was to identify regulatory proteins and receptors underlying ...somatostatin secretion though the use of transcriptomic comparison of purified murine alpha, beta and delta cells.
Methods
Sst-Cre
mice crossed with fluorescent reporters were used to identify delta cells, while
Glu-Venus
(with Venus reported under the control of the
Glu
also known as
Gcg
promoter) mice were used to identify alpha and beta cells. Alpha, beta and delta cells were purified using flow cytometry and analysed by RNA sequencing. The role of the ghrelin receptor was validated by imaging delta cell calcium concentrations using islets with delta cell restricted expression of the calcium reporter GCaMP3, and in perfused mouse pancreases.
Results
A database was constructed of all genes expressed in alpha, beta and delta cells. The gene encoding the ghrelin receptor,
Ghsr
, was highlighted as being highly expressed and enriched in delta cells. Activation of the ghrelin receptor raised cytosolic calcium levels in primary pancreatic delta cells and enhanced somatostatin secretion in perfused pancreases, correlating with a decrease in insulin and glucagon release. The inhibition of insulin secretion by ghrelin was prevented by somatostatin receptor antagonism.
Conclusions/interpretation
Our transcriptomic database of genes expressed in the principal islet cell populations will facilitate rational drug design to target specific islet cell types. The present study indicates that ghrelin acts specifically on delta cells within pancreatic islets to elicit somatostatin secretion, which in turn inhibits insulin and glucagon release. This highlights a potential role for ghrelin in the control of glucose metabolism.
Human embryonic stem cells (hESCs) have great potentials for future cell-based therapeutics. However, their mechanosensitivity to biophysical signals from the cellular microenvironment is not well ...characterized. Here we introduced an effective microfabrication strategy for accurate control and patterning of nanoroughness on glass surfaces. Our results demonstrated that nanotopography could provide a potent regulatory signal over different hESC behaviors, including cell morphology, adhesion, proliferation, clonal expansion, and self-renewal. Our results indicated that topological sensing of hESCs might include feedback regulation involving mechanosensory integrin-mediated cell–matrix adhesion, myosin II, and E-cadherin. Our results also demonstrated that cellular responses to nanotopography were cell-type specific, and as such, we could generate a spatially segregated coculture system for hESCs and NIH/3T3 fibroblasts using patterned nanorough glass surfaces.
Research on human embryonic stem cells (hESCs) has attracted much attention given their great potential for tissue regenerative therapy and fundamental developmental biology studies. Yet, there is ...still limited understanding of how mechanical signals in the local cellular microenvironment of hESCs regulate their fate decisions. Here, we applied a microfabricated micromechanical platform to investigate the mechanoresponsive behaviors of hESCs. We demonstrated that hESCs are mechanosensitive, and they could increase their cytoskeleton contractility with matrix rigidity. Furthermore, rigid substrates supported maintenance of pluripotency of hESCs. Matrix mechanics-mediated cytoskeleton contractility might be functionally correlated with E-cadherin expressions in cell-cell contacts and thus involved in fate decisions of hESCs. Our results highlighted the important functional link between matrix rigidity, cellular mechanics, and pluripotency of hESCs and provided a novel approach to characterize and understand mechanotransduction and its involvement in hESC function.
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