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Sex differences in fatigue resistance of the adductor pollicis (AP) muscle were studied in 24 older adults who were divided into three groups: 12 older men (69.8 +/- 4.60 years), 6 older women not on hormone replacement therapy (HRT) (70.2 +/- 4.02 years), and 6 older women on HRT (68.7 +/- 6.47 years). Fatigue in the AP muscle was induced using an intermittent (5 s contraction, 5 s rest) submaximal voluntary contraction (50% of maximal voluntary contraction (MVC)) protocol, which was continued until exhaustion (i.e., when subjects could either no longer maintain a 5-s contraction at 50% MVC or when the MVC was deemed to be lower than the target force). There was no effect of HRT on MVC or time to fatigue (TTF); therefore, the older women were pooled as one subject group. At baseline, men were stronger than women for MVC (75.9 +/- 18.8 N in men vs. 56.8 +/- 10.0 N in women; P < 0.05) and evoked twitch force (7.3 +/- 1.7 N in men vs. 5.2 +/- 0.8 N in women; P < 0.05). There was no difference in TTF between men and women (14.77 +/- 7.06 min in men vs. 11.53 +/- 4.91 min in women; P > 0.20), nor was there a significant relationship between baseline muscle force and TTF (r = 0.14). There was also no difference in the pattern of fatigue and recovery between the men and women. These results suggest that there is no difference in endurance or fatigue characteristics of the AP muscle in men and women over the age of 65 years, and that baseline muscle force does not predict fatigue resistance in this muscle.  相似文献   

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Any realistic model of human fertility should encompass the distributions and interactions of three time intervals a fecund married woman may experience repeatedly in her childbearing period: (1) waiting time for a conception, (2) gestation period, and (3) period of postpartum amenorrhea. Perrin & Sheps (1964) presented a model in which human reproduction is viewed as a Markov renewal process with a finite number of states. Das Gupta (1973b) presented a general probability model of fertility along the lines suggested by Perrin & Sheps which removes two limitations of their model. First, it does not assume that the distributions of durations of stay in the fertility states are independent of each other. Second, it allows us to study the effect of breast-feeding on demographic characteristics, such as interval between live births or birth rate. Results derived in Das Gupta (1973b) include the distributions of time intervals and the exact probabilities of different states at a particular time. The present paper includes additional results pertaining to the same general model, such as the distribution of number of conceptions in a fixed period of time, the distribution of time needed for a fixed number of conceptions, pregnancy rate and fertility rate, and the distribution of the time elapsed since last live birth. The general results are applied to specific models to obtain some known results.  相似文献   

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Summary A major objective of the CIMMYT Maize Program is to develop open-pollinated varieties of maize (Zea mays L.) that are well adapted to a wide range of environments. To achieve this breeding goal, it is essential that the program use a stability technique that will identify high-yielding, stable genotypes accurately in international trials conducted under different environmental conditions. The objective of this study was to compare a spatial method with a modified conventional regression analysis method to determine the yield stability of 27 CIMMYT maize varieties evaluated at 37 locations. The methods also were compared on the basis of their consistency in assessing the stability of varieties when certain locations were omitted, and when subsets of varieties were analyzed. The varieties found to be stable by the spatial method with all sites included in the analysis were also stable (1) when the lowest and highest yielding sites were excluded from the analyses, and (2) when the varieties were considered, along with others, as a subset of the original group of materials. Stability parameters determined by regression analysis, however, varied for some varieties when (1) extreme sites were excluded, and (2) a subset of entries was considered in isolation. Because the spatial method was more consistent in identifying high-yielding stable varieties, it was considered the more useful of the two methods.  相似文献   

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The objective of the study was to compare the level of dissatisfaction with body image of men and women of the social elite in the Wielkopolska region, Poland, in the light of anthropometric indicators.  相似文献   

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Muscle power, the product of force × velocity, is a critical determinant of function in older adults. Resistance training (RT) at high speed has been shown to improve peak muscle power in this population; however, different functional tasks may benefit from the improvement of power at values other than "peak" values, for example, tasks that require a greater velocity component or a greater force component. This study compared the effect of high-speed RT on muscle performance (peak power [PP] and its components [PP force and PP velocity] and overall peak velocity [VEL]) across a broad range of external resistances. Thirty-eight older men and women were randomized to high-speed power training at 40% of the 1-repetition maximum (1RM) (n = 13 [74.1 ± 6.4 years]); traditional RT at 80% 1RM (n = 13 [70.1 ± 7.0 years]); or control (n = 12 [72.8 ± 4.1 years]). Measures of muscle performance were obtained at baseline and after the 12-week training intervention. Muscle power and 1RM strength improved similarly with both high-speed and traditional slow-speed RT. However, speed-related muscle performance characteristics, PP velocity and overall VEL, were most positively impacted by high-speed power training, especially at lower external resistances. Because gains in speed-related measures with high-speed training compared to traditional RT do not come at the expense of other muscle performance outcomes, we recommend using an RT protocol in older adults that emphasizes high-speed movements at low external resistances.  相似文献   

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It has been found that fertility alpha 2-microglobulin content in male and female serum does not exceed 20 ng/ml and 40 ng/ml, respectively. A high level of fertility alpha 2-microglobulin was found in the serum in early pregnancy, with its concentration decreased by parturition.  相似文献   

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A survey of the fertility of Icelandic stallions   总被引:1,自引:0,他引:1  
Very limited information is available on the breeding performance of Icelandic stallions, let alone the effect that management practices may have had on such performance. As an extensively kept, largely genetically isolated breed of horse it provides a good model for the study of factors that affect reproductive performance without the additional complication of selective breeding, infectious infertility and breed effect. A survey was conducted using 27 Icelandic stallions covering 1590 mares within the normal Icelandic breeding system (May to September). During the season, stallions cover mares within three periods of time, each period being of a similar length (average 35.5 days). During period 1, mares are covered in hand and at pasture. During periods 2 and 3, all mares are covered at pasture. The overall fertility rate for Icelandic stallions was calculated. The effect of a range of variables on fertility was investigated statistically using a number of models in an attempt to minimise the effect of confounding factors. An overall adjusted fertility rate for Icelandic stallions of 67.7% was obtained. The following factors were shown to have a significant effect on fertility: age of mare (P<0.001), training level of stallion (P<0.05) and method of breeding (P<0.05). For some individual stallions reproductive status of the mare also had a significant (P<0.001) effect. Many of these factors have been observed to effect FR in other more intensively managed equine populations. However, the less dramatic detrimental effect of age and the lack of a significant effect of mare reproductive status in most stallions suggests that infertility problems are less evident in Icelandic mares, possibly due to less emphasis on selection for athletic performance and the accepted culling of subfertile stock.  相似文献   

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Multicenter studies involved 1449 male and 131 female patients operated for the atherosclerotic ischemia of the lower limbs. About 50% of all limbs were in the III or IV stage of ischemia (according to Fontaine's classification) before surgery. Atherosclerotic lesions involved mainly aortoiliac segment in the majority of patients. Early results of surgery were similar in both men and women. An improvement during a 5-year follow up period was noted more frequently in women than in men--86% and 68.5% of limbs respectively. Late result of lumbar sympathectomy was similar in both groups. Limb amputation and mortality rates were similar in both groups in the early postoperative period and during a 5-year follow up as well.  相似文献   

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We measured detailed regional depositionpatterns of inhaled particles in healthy adult male(n = 11; 25 ± 4 yr of age) and female (n = 11; 25 ± 3 yr of age)subjects by means of a serial bolus aerosol delivery technique formonodisperse fine [particle diameter(Dp) = 1 µm] and coarse aerosols(Dp = 3 and 5 µm). The bolus aerosol (40 ml half-width) was delivered to a specificvolumetric depth (Vp) of the lung ranging from 100 to 500 ml with a50-ml increment, and local deposition fraction (LDF) was assessed for each of the 10 local volumetric regions. In all subjects, the deposition distribution pattern was very uneven with respect to Vp,showing characteristic unimodal curves with respect to particle sizeand flow rate. However, the unevenness was more pronounced in women.LDF tended to be greater in all regions of the lung in women than inmen for Dp = 1 µm. For Dp = 3 and 5 µm, LDF showed a marked enhancement in the shallow region of Vp  200 ml in women compared with men(P < 0.05). LDF in women wascomparable to or smaller than those of men in deep lung regions of Vp > 200 ml. Total lung deposition was comparable between men and womenfor fine particles but was consistently greater in women than men forcoarse particles regardless of flow rates used: the difference rangedfrom 9 to 31% and was greater with higher flow rates(P < 0.05). The results indicatethat 1) particledeposition characteristics differ between healthy men and women undercontrolled breathing conditions and2) deposition in women is greaterthan that in men.

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Androphilia refers to sexual attraction and arousal to adult males, whereas gynephilia refers to sexual attraction and arousal to adult females. The kin selection hypothesis for male androphilia suggests that androphilic males have been selected to act as “helpers-in-the-nest,” caring for nieces and nephews and, by extension, increasing their indirect fitness. Previous research has demonstrated that Samoan male androphiles (known locally as fa'afafine) exhibit significantly higher altruistic tendencies toward nieces and nephews compared to Samoan women and gynephilic men. Elevated avuncular tendencies must translate into real-world avuncular behavior if they are to have any impact on the fitness of nieces and nephews and the uncles themselves. The present study examined whether Samoan fa'afafine exhibit higher altruistic behavior toward nieces and nephews compared to women and gynephilic men. We used money given to, and received from, oldest and youngest siblings' sons and daughters as a behavioral assay of kin altruism. Compared to women and gynephilic men, fa'afafine gave significantly more money to their youngest siblings' daughters. No group differences were observed for money received from nieces and/or nephews. There were no correlations between number of children parented and monetary exchanges with the niece and nephew categories examined, suggesting that childlessness cannot account for why fa'afafine give more money to their youngest siblings' daughters. These findings are consistent with the kin selection hypothesis for male androphilia.  相似文献   

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OBJECTIVE: To evaluate the efficacy of INFORM HPV using the SurePath collection method in women whose Pap tests indicated abnormal results. STUDY DESIGN: Ninety-two women from the gynecology clinics at The University of Texas M.D. Anderson Cancer Center who had Pap tests and underwent follow-up biopsies were selected for the study. This included 51 women with atypical squamous cells of undetermined significance (ASCUS), 23 women with low-grade squamous intraepithelial lesion (LSIL), 15 women with high-grade squamous intraepithelial lesion (HSIL) and 3 women with negative Pap results. The INFORM HPV, an in situ hybridization assay, testing for oncogenic types of HPV was performed, and the results were compared with follow-up biopsies. RESULTS: The positive rate of the INFORM HPV increased with higher grades of cytology diagnoses. The sensitivity of the INFORM HPV testing for predicting high-grade cervical intraepithelial neoplasia (CIN 2/3) also increased with higher grades of cytology diagnoses. A negative predictive value (NPV) of 94.9% and a specificity of 80.4% for predicting CIN 2/3 were observed in the ASCUS group. CONCLUSION: Using SurePath Pap specimens, the INFORM HPV lacks sufficient sensitivity and NPV for predicting CIN 2/3 in women with ASCUS. Therefore, use of the test as a triage tool is limited.  相似文献   

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John  Bancroft 《Journal of Zoology》1987,213(3):445-454
The extent to which the sexuality of women shows a predictable menstrual cyclicity varies considerably from woman to woman, though the most common times for peaks of sexual interest are the pre- and post-menstrual weeks, not the middle of the cycle. Evidence is presented suggesting that mood is an important determinant of the post-menstrual peak of sexuality, whereas the pre-menstrual peak may depend on other mechanisms such as a delayed effect of the mid-cycle rise in testosterone.
Generally, the evidence for a relationship between hormones and sexual behaviour is much more variable and inconsistent in women than in men. Various explanations for this difference have been proposed, including a greater genetic variability of hormone-behaviour relationships in women. Evidence, relevant to this hypothesis, of a relationship between frequency of sexual activity and the fertility of the ovarian cycle is reviewed and alternative explanations for the findings are considered.  相似文献   

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