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Kensuke Nakata 《Biology letters》2016,12(2)
Monandry, in which a female has only one mating partner during the reproductive period, is established when a female spontaneously refrains from re-mating, or when a partner male interferes with the attempts of a female to mate again. In the latter case, however, females often have countermeasures against males, which may explain why polyandry is ubiquitous. Here, I demonstrate that the genital appendage, or scape, of the female orb-web spider (Cyclosa argenteoalba) is injured after her first mating, possibly by her first male partner. This female genital mutilation (FGM) permanently precludes copulation, and females appear to have no countermeasures. FGM is considered to confer a strong advantage to males in sexual conflicts over the number of female matings, and it may widely occur in spiders. 相似文献
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Sarwer DB Cash TF Magee L Williams EF Thompson JK Roehrig M Tantleff-Dunn S Agliata AK Wilfley DE Amidon AD Anderson DA Romanofski M 《Plastic and reconstructive surgery》2005,115(3):931-938
This large, multisite study investigated female college students' experiences with and attitudes about cosmetic surgery. The study also assessed the relationship between several aspects of body image, including appearance satisfaction and investment and symptoms of body dysmorphic disorder, and interest in cosmetic surgery. Thirty (5 percent) of the 559 women surveyed reported that they had undergone cosmetic surgery. Two thirds of respondents reported knowing someone who had received cosmetic surgery, and approximately one third indicated that a family member had undergone surgery. Overall, participants held relatively favorable attitudes about surgery. Regression analysis suggested that a greater psychological investment in physical appearance and greater internalization of mass media images of beauty predicted more favorable attitudes toward cosmetic surgery. Fourteen women (2.5 percent) screened positive for body dysmorphic disorder based on the nature and severity of their self-reported body-image concerns. Results of this study provide new information on young women's experiences and attitudes about cosmetic surgery and how these attitudes relate to body image. 相似文献
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Hoeyberghs JL 《BMJ (Clinical research ed.)》1999,318(7182):512-516
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Nephilid spiders are known for gigantic females and tiny males. Such extreme sexual dimorphism and male-biased sex ratios result in fierce male–male competition for mates. Intense sperm competition may be responsible for behaviors such as mate guarding, mate binding, opportunistic mating, genital mutilation, mating plugs and male castration (eunuchs). We studied the mating biology of two phylogenetically, behaviorally and morphologically distinct south-east Asian nephilid spider species ( Herennia multipuncta, Nephila pilipes ) in nature and in the laboratory. Specifically, we established the frequencies and effectiveness of plugging (a plug is part of the male copulatory organ), and tested for male and female copulatory organ reuse. Both in nature and in the laboratory, plug frequencies were higher in H. multipuncta (75–80% females plugged) compared with N. pilipes (45–47.4%), but the differences were not significant. Plugs were single and effective (no remating) in H. multipuncta but multiple and ineffective (remating possible) in N. pilipes . In Herennia , the males plugged when the female was aggressive and in Nephila plugging was more likely when mating with previously mated and larger females. Further differences in sexual biology are complete palpal removal and higher sexual aggressiveness in Herennia (sexual cannibalism recorded for the first time), and mate binding in Nephila . Thus, we propose the following evolutionary hypothesis: nephilid plugging was ancestrally successful and enabled males to monopolize females, but plugging became ineffective in the phylogenetically derived Nephila . If the evolution of nephilid sexual mechanisms is driven by sexual conflict, then the male mechanism to monopolize females prevailed in a part of the phylogeny, but the female resistance to evade monopolization ultimately won the arms race. 相似文献
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David B Sarwer Thomas A Wadden Linton A Whitaker 《Plastic and reconstructive surgery》2002,109(1):363-9; discussion 370-1
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Female sexual arousal: genital anatomy and orgasm in intercourse 总被引:1,自引:0,他引:1
In men and women sexual arousal culminates in orgasm, with female orgasm solely from sexual intercourse often regarded as a unique feature of human sexuality. However, orgasm from sexual intercourse occurs more reliably in men than in women, likely reflecting the different types of physical stimulation men and women require for orgasm. In men, orgasms are under strong selective pressure as orgasms are coupled with ejaculation and thus contribute to male reproductive success. By contrast, women's orgasms in intercourse are highly variable and are under little selective pressure as they are not a reproductive necessity. The proximal mechanisms producing variability in women's orgasms are little understood. In 1924 Marie Bonaparte proposed that a shorter distance between a woman's clitoris and her urethral meatus (CUMD) increased her likelihood of experiencing orgasm in intercourse. She based this on her published data that were never statistically analyzed. In 1940 Landis and colleagues published similar data suggesting the same relationship, but these data too were never fully analyzed. We analyzed raw data from these two studies and found that both demonstrate a strong inverse relationship between CUMD and orgasm during intercourse. Unresolved is whether this increased likelihood of orgasm with shorter CUMD reflects increased penile–clitoral contact during sexual intercourse or increased penile stimulation of internal aspects of the clitoris. CUMD likely reflects prenatal androgen exposure, with higher androgen levels producing larger distances. Thus these results suggest that women exposed to lower levels of prenatal androgens are more likely to experience orgasm during sexual intercourse. 相似文献
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Body dysmorphic disorder and cosmetic surgery 总被引:1,自引:0,他引:1
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Pitanguy I 《Plastic and reconstructive surgery》2000,105(4):1517-26; discussion 1527
Although traits that are specific to different social and cultural groups may express the uniqueness in what humans regard as beautiful, the quest for beauty itself is universal. It is intrinsically related to the search for harmony as a means of achieving intimate well being. Inevitably, aging brings changes that are undesirable. The face, because of its exposure and expression and the constant action of gravity, is frequently the main focus of anxiety in individuals who have attained a certain age because their face has flaccid skin, marked lines of expression, and fat deposits. Motivations for surgery for the aging face are generally deeply hidden and include personal, social, and professional factors. These motivations might not be perceived or investigated by the surgeon who, in turn, will not have done a complete and precise diagnosis. This evaluation is the most valuable tool for determining the most favorable procedure for each patient. 相似文献
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Krieger LM 《Plastic and reconstructive surgery》2002,110(2):614-619
Discount cosmetic surgery is a topic of interest to plastic surgeons. To understand this trend and its effects on plastic surgeons, it is necessary to review the economics of cosmetic surgery, plastic surgery's practice environment, and the broader business principles of service industries.Recent work looked at the economics of the plastic surgery market. This analysis demonstrated that increased local density of plastic surgeons was associated with lower adjusted fees for cosmetic procedures. A survey of plastic surgeons about their practice environment revealed that 93 percent categorized the majority of their patients as very or moderately price-sensitive. Fully 98 percent described their business climate as very or moderately competitive and most plastic surgeons thought they lost a sizable number of cosmetic patients within the last year for reasons of price.A standard industry analysis, when applied to cosmetic surgery, reveals the following: an increased number of surgeons leads to lower fees (reducing their bargaining power as suppliers), patients are price-sensitive (increasing their bargaining power as buyers), and there are few barriers to entry among providers (allowing potential new entrants into the market). Such a situation is conducive to discounting taking hold-and even becoming the industry norm.In this environment, business strategy dictates there are three protocols for success: discounting, differentiation, and focus. Discounting joins the trend toward cutting fees. Success comes from increasing volume and efficiency and thus preserving profits. Differentiation creates an industrywide perception of uniqueness; this requires broadly positioning plastic surgeons as holders of a distinct brand identity separate from other "cosmetic surgeons." The final strategy is to focus on a particular buyer group to develop a market niche, such as establishing a "Park Avenue" practice catering to patients who demand a prestigious surgeon, although this is likely a small segment of the overall patient population. Plastic surgeons that buck the trend toward discount cosmetic surgery must take concrete and potentially costly steps to implement a plausible strategy for distinguishing their practices within the crowded cosmetic surgery market. 相似文献