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1.
Objective: The aim of this study was to evaluate the relationship between objectively measured physical activity (ACT), particularly intensity of physical activity (iACT), and body fat percentage (BF%) in 278 middle‐aged women. Secondary purposes were to ascertain the association between physical activity duration (dACT) and BF% and the extent to which potentially confounding factors, including total ACT, energy intake, body weight, and season of assessment, influenced the relationship between iACT and BF%. Research Methods and Procedures: A cross‐sectional design was used. Subjects were apparently healthy, 35 to 45 years old, premenopausal, nonsmokers, with BMIs < 30 kg/m2. Approximately 90 percent were white, 81% were married, and 37% were college graduates. ACT was assessed using Computer Science and Application accelerometers worn for 7 consecutive days. The accelerometers recorded movement continuously, and activity counts were collapsed into 10‐minute epochs. Intensity was indexed using seven activity count cut‐off points, and duration was based on the number of 10‐minute epochs at each intensity level. BF% was assessed using multiple measurements in the Bod Pod. Energy intake was measured using 7‐day weighed diet records during the same week subjects wore the accelerometers. Results: BF% was strongly and inversely associated with iACT and dACT. Controlling for energy intake and body weight strengthened the relationships among iACT, dACT, and BF%. Control of total ACT weakened the association. Discussion: Engaging in higher intensity and/or longer duration ACT is associated with lower BF% compared with lower intensity and/or shorter durations of activity.  相似文献   

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The continuously increasing usage of cell phones has raised concerns about the adverse effects of microwave radiation (MWR) emitted by cell phones on health. Several in vitro and in vivo studies have claimed that MWR may cause various kinds of damage in tissues. The aim of this study is to examine the possible effects of exposure to low‐intensity MWR on DNA and oxidative damage in the livers of rats. Eighteen Sprague–Dawley male rats were divided into three equal groups randomly (n = 6). Group 1 (Sham‐control): rats were kept under conditions the same as those of other groups, except for MWR exposure. Group 2: rats exposed to 1800 MHz (SAR: 0.62 W/kg) at 0.127 ± 0.04 mW/cm2 power density, and Group 3: rats exposed to 2,100 MHz (SAR: 0.2 W/kg) at 0.038 ± 0.03 mW/cm2 power density. Microwave application groups were exposed to MWR 2 h/day for 7 months. At the end of the exposure period, the rats were sacrificed and DNA damage, malondialdehyde (MDA), 8‐hydroxydeoxyguanosine (8‐OHdG), and total oxidant‐antioxidant parameter analyses were conducted in their liver tissue samples. It was found that 1800 and 2100 MHz low‐intensity MWR caused a significant increase in MDA, 8‐OHdG, total oxidant status, oxidative stress index, and comet assay tail intensity (P < 0.05), while total antioxidant status levels (P < 0.05) decreased. The results of our study showed that whole‐body exposure to 1800 and 2100 MHz low‐intensity MWR emitted by cell phones can induce oxidative stress by altering oxidant‐antioxidant parameters and lead to DNA strand breaks and oxidative DNA damage in the liver of rats. Bioelectromagnetics. 2021;42:76–85. © 2020 Bioelectromagnetics Society  相似文献   

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Guozhen Wu  Peijie Wang 《Chirality》2015,27(11):820-825
A bond polarizability algorithm was developed and applied to interpret the Raman optical activity (ROA) intensity. It is demonstrated that for the chiral molecule such as S(+)2,2‐dimethyl‐1,3‐dioxolane‐4‐methanol there exists approximate (or symmetry breaking) mirror reflection that reverses the signs of the differential bond polarizabilities of the pair bond coordinates that are related to each other by the mirror reflection, just like that between the right and left enantiomers. The magnitude difference of the differential bond polarizabilities of the pair bond coordinates becomes smaller as they are farther away from the asymmetric atom. Hence, that the asymmetric atom (center) plays a central role in ROA is confirmed from a spectroscopic viewpoint. Meanwhile, the concept of intramolecular enantiomerism is proposed. Chirality 27:820–825, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   

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Young adults (YA) are underrepresented in behavioral weight loss programs and achieve poorer outcomes than older adults (OA). There has been a call to develop programs specifically targeting this age group. This study examined the performance of YA enrolled in a low‐intensity, team‐based weight loss campaign and compared their outcomes to OA to determine the utility of such an approach for weight loss in this population. Shape Up Rhode Island (SURI) 2009 was a 12‐week online team‐based weight loss and exercise competition (N = 6,795, 81% female, 94% white, age = 44.7 ± 11.2, BMI = 29.4 ± 5.9). YA was defined as 18–35 years and OA as >35 years; YA and OA were compared on enrollment, retention, weight loss, and change in steps. A total of 1,562 YA enrolled and 715 completed the program. Fewer YA completed compared with OA (46 vs. 62%, P < 0.001). However, among completers, YA achieved greater percent weight loss (‐4.5 ± 4.0 vs. ?3.8 ± 3.2%) and greater daily step change (+1,578.2 ± 3,877.2 vs. +1,342.2 ± 3,645.7) than OA (P's < 0.001). Further, more YA completers achieved a ≥5% weight loss (40 vs. 29%, P < 0.001). Findings were consistent in the overweight/obese (OW/OB) subsample, and using ≤25 years of age as the cut off for YA. Weight losses among YA in this low‐intensity weight loss campaign were quite promising, with over 700 YA completing the program and on average achieving a 4.5% weight loss. Indeed, the potential public health impact of such an approach is substantial; future efforts to develop programs for this age group may benefit from using a low‐intensity, team‐based approach.  相似文献   

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At least 60 min of daily physical activity (PA) are recommended for weight control, a target achieved by only 3% of obese (OB) women. The purposes of this study were to examine (i) the affective responses of normal‐weight (NW), overweight (OW), and OB middle‐aged sedentary women to exercise of increasing intensity and (ii) the relationship of affective responses to self‐efficacy and social physique anxiety. The women participated in a graded treadmill protocol to volitional exhaustion while providing ratings of pleasure–displeasure and perceived activation each minute. The Activation Deactivation Adjective Check List (AD ACL) was also completed before and after exercise. The affective responses of NW and OW women did not differ. However OB women gave lower pleasure ratings during the incremental protocol and reported lower Energy scores immediately after the protocol. Social physique anxiety, but not self‐efficacy, was inversely related to pleasure and energy. The lower levels of pleasure and energy experienced by OB than nonobese women could account in part for their dramatically low levels of PA participation. Modifying the cognitive antecedents of social physique anxiety might be a useful intervention strategy.  相似文献   

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Summary In individually matched case–control studies, when some covariates are incomplete, an analysis based on the complete data may result in a large loss of information both in the missing and completely observed variables. This usually results in a bias and loss of efficiency. In this article, we propose a new method for handling the problem of missing covariate data based on a missing‐data‐induced intensity approach when the missingness mechanism does not depend on case–control status and show that this leads to a generalization of the missing indicator method. We derive the asymptotic properties of the estimates from the proposed method and, using an extensive simulation study, assess the finite sample performance in terms of bias, efficiency, and 95% confidence coverage under several missing data scenarios. We also make comparisons with complete‐case analysis (CCA) and some missing data methods that have been proposed previously. Our results indicate that, under the assumption of predictable missingness, the suggested method provides valid estimation of parameters, is more efficient than CCA, and is competitive with other, more complex methods of analysis. A case–control study of multiple myeloma risk and a polymorphism in the receptor Inter‐Leukin‐6 (IL‐6‐α) is used to illustrate our findings.  相似文献   

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Objective: Previous studies have shown that fat metabolism is different in upper body (UB) and lower body (LB) obese women. The present study investigated whether the effect of low‐intensity exercise training on fat metabolism is different in UB and LB obese premenopausal women. Research Methods and Procedures: Twenty‐one healthy, premenopausal women with either LB obesity (waist‐to‐hip ratio of ≤0.79; n = 8) or UB obesity (waist‐to‐hip ratio of ≥0.85; n = 13) participated in the present study. The UB obese women were matched and randomly divided in an exercise training group (UB) and a nonexercising control group (UB‐C). Subjects in the UB and LB groups participated in a low‐intensity exercise training program (40% Vo 2max) three times per week for 12 weeks. Before and after the intervention, measurements of fat metabolism at rest and during exercise, body composition, and maximal aerobic capacity were performed. Results: Exercise training did not change the respiratory exchange ratio at rest in the UB and LB groups. During exercise, relative fat oxidation increased in the UB group by 19% (p < 0.05), whereas no change in the LB and UB‐C groups was found. Plasma free fatty acid oxidation did not change by exercise training, and nonplasma fatty acid oxidation tended to increase in the UB group compared with the UB‐C group (p = 0.08). Discussion: Low‐intensity exercise training increased the contribution of fat oxidation to total energy expenditure during exercise but not at rest in UB obese women. Exercise training had no significant effect on fat metabolism in the LB obese women.  相似文献   

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Sexual selection is one of the main processes involved in the emergence and maintenance of heritable color polymorphisms in a variety of taxa. Here, we test whether the intensity of sexual selection, estimated from population sex ratio, predicts morph diversity in Podarcis muralis, a color polymorphic lizard with discrete white, yellow, orange, white‐orange, and yellow‐orange male and female phenotypes (i.e., morphs). In a sample of 116 Pyrenean populations and 5421 lizards, sex ratios (m/f) vary from 0.29 to 2.5, with the number of morphs for each sex ranging from 2 to 5. Male‐biased sex ratios are associated with increased morph diversity as measured with Shannon's diversity index. The main factor accounting for this relationship is male morph richness (i.e., the number of morphs). In contrast, female morph diversity is not related to sex ratio. These results suggest a relationship between the intensity of male intrasexual competition and male morph diversity. While other selective forces may interact with sexual selection in maintaining the color polymorphisms in P. muralis, this evidence suggests a complex evolutionary scenario possibly involving frequency‐dependent selection of alternative reproductive tactics and/or complex balancing selection.  相似文献   

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Drip‐tips are a common feature of the leaves of rain forest trees, but their functional significance remains contested. The most widely accepted hypothesis is that drip‐tips assist drainage of the lamina thereby aiding drying of the leaf surface and reducing the rate of colonization and abundance of epiphyllic organisms. The drying action of drip‐tips may also enhance transpiration and reduce the need for investment in support structures. Furthermore, drip‐tips may help prevent splash erosion around the base of the tree. Data from 130 forest Amazonian plots are used to investigate the abundance and distribution of drip‐tips and, through regression methods that incorporate spatial autocorrelation, seek to identify associations between the frequency of drip‐tips and a range of climatic variables. The average frequency of species and trees with drip‐tips across all plots was 32 and 33 percent, respectively. Trees and species with drip‐tips were significantly more prevalent in the Central‐East Amazon than the other regions. Drip‐tips were also associated with tree species that have smaller maximum heights and with trees with smaller trunk diameters. The proportion of species and individuals with drip‐tips was more strongly correlated with precipitation of the wettest trimester than with total annual precipitation or length of the dry season. Our results extend and provide support for both existing hypotheses for the functional benefit of possessing a drip‐tip. Moreover, the currently unrecognized macrogeographic association between the frequency of drip‐tips in trees of the tropical forest understory and areas of heavy precipitation suggests a new function for this trait.  相似文献   

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Guozhen Wu  Peijie Wang 《Chirality》2014,26(5):255-259
The bond polarizability and differential bond polarizability are introduced to interpret the Raman and Raman optical activity (ROA) intensities, calculated by the ab initio method. Chiral S 2‐amino 1‐propanol is taken as a model molecule. Through these bond polarizabilities, we observe that symmetric and antisymmetric coordinates are, respectively, more significant in Raman and ROA. It is noted that in S 2‐amino 1‐propanol those bonds lying on a common plane share the same differential bond polarizability sign while that of the asymmetric C‐H bond which protrudes out of the plane possesses the opposite sign. We conclude that ROA can offer more stereostructural implications than Raman and that the differential bond polarizability is potentially the appropriate parameter in interpreting the 3D configuration of a molecule. Chirality 26:255–259, 2014. © 2014 Wiley Periodicals, Inc.  相似文献   

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Home range (HR) size variation is often linked to resource abundance, with sex differences expected to relate to sex‐specific fitness consequences. However, studies generally fail to disentangle the effects of the two main drivers of HR size variation, food and conspecific density, and rarely consider how their relative influence change over spatiotemporal scales. We used location data from 77 Eurasian lynx (Lynx lynx) from a 16‐year Scandinavian study to examine HR sizes variation relative to prey and conspecific density at different spatiotemporal scales. By varying the isopleth parameter (intensity of use) defining the HR, we show that sex‐specific effects were conditional on the spatial scale considered. Males had larger HRs than females in all seasons. Females' total HR size declined as prey and conspecific density increased, whereas males' total HR was only affected by conspecific density. However, as the intensity of use within the HR increased (from 90% to 50% isopleth), the relationship between prey density and area showed opposing patterns for females and males; for females, the prey density effect was reduced, while for males, prey became increasingly important. Thus, prey influenced the size of key regions within male HRs, despite total HR size being independent of prey density. Males reduced their HR size during the mating season, likely to remain close to individual females in estrous. Females reduced their HR size postreproduction probably because of movement constrains imposed by dependent young. Our findings highlight the importance of simultaneously considering resources and intraspecific interactions as HR size determinants. We show that sex‐specific demands influence the importance of prey and conspecific density on space use at different spatiotemporal scales. Thus, unless a gradient of space use intensity is examined, factors not related to total HR size might be disregarded despite their importance in determining size of key regions within the HR.  相似文献   

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The dawn chorus is a period of peak singing activity of many songbirds. Numerous studies have sought to understand this widespread phenomenon, and many hypotheses have been proposed to explain the dawn chorus. The social dynamics hypothesis proposes that dawn singing plays an important role in the announcement of territorial occupancy and the regulation of social relationships between males; it predicts that the dawn chorus vocal behavior varies with changes in social relationships. In this study, we tested the influence of territorial insertions and the number of neighbors, on the intensity of the brownish‐flanked bush warbler (Cettia fortipes)'s dawn singing. We found that simulated territorial insertions (playback) caused the males to increase their dawn singing significantly the next day, and males that had many neighbors exhibited more intense dawn singing than did males with few neighbors. Our study provides evidence that dawn singing plays an important role in the announcement of territorial occupancy and the regulation of the social relationships between the males.  相似文献   

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The acetylcholinesterase inhibition by enantiomers of exo‐ and endo‐2‐norbornyl‐Nn‐butylcarbamates shows high stereoselelectivity. For the acetylcholinesterase inhibitions by (R)‐(+)‐ and (S)‐(?)‐exo‐2‐norbornyl‐Nn‐butylcarbamates, the R‐enantiomer is more potent than the S‐enantiomer. But, for the acetylcholinesterase inhibitions by (R)‐(+)‐ and (S)‐(?)‐endo‐2‐norbornyl‐Nn‐butylcarbamates, the S‐enantiomer is more potent than the R‐enantiomer. Optically pure (R)‐(+)‐exo‐, (S)‐(?)‐exo‐, (R)‐(+)‐endo‐, and (S)‐(?)‐endo‐2‐norbornyl‐Nn‐butylcarbamates are synthesized from condensations of optically pure (R)‐(+)‐exo‐, (S)‐(?)‐exo‐, (R)‐(+)‐endo‐, and (S)‐(?)‐endo‐2‐norborneols with n‐butyl isocyanate, respectively. Optically pure norborneols are obtained from kinetic resolutions of their racemic esters by lipase catalysis in organic solvent. Chirality 2010. © 2009 Wiley‐Liss, Inc.  相似文献   

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A sub‐acute electromagnetic field (EMF) biological effect study was carried out on rats exposed in the Transverse ElectroMagnetic exposure chamber at 171 MHz Continuous Wave (CW). The experiments involved three exposure levels (15, 25, and 35 V/m) for 15 days with triplicate parallel sham‐exposed controls in each series. All exposure conditions were simulated for the evaluation of the electromagnetic energy distribution and specific absorption rate (SAR) in the rat phantoms. Studies have shown a biphasic biological response depending on time and absorbed electromagnetic energy. Under low SAR, approximately 0.006 W/kg, EMF exposure leads to the stimulation of adrenal gland activity. This process is accompanied by an initial increase of daily excretion of corticosterone and Na+, which is seen as a higher Na+/K+ ratio, followed by a decrease of these parameters over time. It is possible that EMF exposure causes a stress response in animals, which is seen as an increased adrenal activity. Bioelectromagnetics. 2019;40:578–587. © 2019 Bioelectromagnetics Society.  相似文献   

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Since the future of anthropology in Australia is clouded, the address takes a look at where it has been coming from. Rather than a distinctive regional school, the discipline in Australia has been part of anthropology in the UK and the USA. In common with anthropology elsewhere, it lacks a distinctive theoretical stance, but draws on the theory current in the other social sciences. Recognising that what makes anthropology ‘special’ is the field work experience, the address reflects on the history and nature of this practice.  相似文献   

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