卧姿人体垂直振动模型及其应用研究进展概述

1研究的意义在通常情况下，救护车中卧姿伤病员主要承受垂直（背－胸向）振动和纵向角振动，只有在救护车制动、转弯或在扭曲、迂回路面行驶的情况下，人体承受的水平振动才较为显著。另一方面，纵向角振动可以部分分解转化为垂直振动来加以考虑。因而研究卧姿人体垂直振动响应特性对分析和评价救护车的平顺性具有重要意义1。当研究卧姿人体对全身振动的响应时，弄清楚人体的振动动力学特性至关重要。人体机械激励点阻抗是描述人体生物动力学响应的重要参数，是探究人体振动动力学特性的有效手段。它是表征机械振动对人体输入的重要概念…     

纵向角振动对卧位人体的作用特性及研究必要性分析

1概述人体经常暴露于振动环境中。机械振动通过人体表面作用于人体，在人体内引起一系列生理、心理反应。轻微的振动对人体是无害的，但一定强度的振动会给人体健康造成危害，引起前庭器官、内分泌系统、循环系统和植物神经等一系列改变，并产生不协调障碍，面色苍白恶心等症状，引起疲劳和劳动能力下降。过分强烈的振动还可直接导致内脏器官的机械损伤。为了保障人体健康，提高汽车的乘座舒适性，国内外对振动对人体的影响进行了大量的研究工作，获得了一系列人体的振动的响应规律。但同时也存在不少有待研究的问题。1．1全身振动研究的主…     

全身振动对驾驶员心血管系统影响的调查

全身振动对驾驶员心血管系统影响的调查江苏省连云港市卫生防疫站白彩云全身振动对人体的危害，国内外许多资料已有报道，而有关全身振动对心血管系统的影响，研究较少。为探讨接振与心血管疾病发生关系，本文对某港口部分建港运输汽车驾驶员进行调查，现将调查情况摘要作...     

汽车司机作业对脊椎的影响

关于振动对人体的危害,以往着重于局部振动的研究。一般认为全身振动对机体的运动、消化系统、前庭及视觉,甚至对脑、心血管均有影响~[1,2]。然而,全身振动对人体脊椎影响的研究甚少,为此,我们于1991年3月以汽车司机为观察对象,进行了调查。     

全身振动环境舒适性评价

全身振动普遍地存在于各种生产活动和日常工作中,严重地危害着人们的身体健康。全身振动作为一种扩散性物理刺激物,不但直接影响人们的工作、学习和环境的舒适性,而且还会对人体产生一定的生理和病理损害。因此,全身振动的职业危害已受到各方面的关注。     

浅谈振动对机体各系统的影响

所有现代工业部门,都拥有会产生强烈振动的机器,设备及动力工具,而且这类振动还能传递给操作者。接触振动的方式可分为局部振动和全身振动。有些工种同时受到局部和全身振动的作用。当机体接触大振幅后,会产生不良影响,甚至引起病损。振幅越大,接触时间越长对人体的危害越大,振动病的发生越快。人体受振后,振动波在组织内的传播,由于各组织结构不同,其大小顺序为骨、结缔组织、软骨、肌肉、腺组织和脑组织。     

谈谈机械振动对人体的影响

研究机械振动对人体影响的一些资料说明,机械振动对人体的影响及其严重性主要决定于振动的振幅、频率、振动作用的时间、以及经受振动的人体各部分的性能。 振动对人体的第一个影响是人体感觉,感觉是通过人体的许多感受器接收的,如表皮中的末梢神经、细胞组织中的环层小体、肌肉中的肌梭和高尔基腱梭、以及前庭器官等。人体对振动的感觉有一个振幅和频率的范围,当振幅和频率在这个范围内时人体才感觉到振动。例如,人体对加到手指端的切向振动感觉的最小临界值是在频率为200～300Hz和振幅接近10~(-8)m时、而对站或坐在垂直振动平台上受到全身振动的振觉最小临界值是在1～10Hz的频率范围内。 在人体能感觉到振动的频率和振幅范围内,在振动强度相同的情况下,由于频率的不同,人体的     

全身振动对石油工人腰椎损伤的调查

全身振动是涉及工种较多的一种职业危害因素。随着工业生产和医学的发展,全身振动对人体的危害越来越受到国内外的重视〔1～3〕。为调查全身振动对石油工人腰椎的损伤,我们对辽河油田钻井、固井、压裂和钻前拖拉机作业的全身振动进行了三轴向加速度测试,并对153名全身振动作业工人和31名对照组工人进行了腰椎Ｘ线正、侧位摄片检查。结果报告如下。对象与方法　对象:振动组为153名辽河油田钻井、固井、压裂和钻前拖拉机作业工人,平均年龄335岁,平均工龄118年;对照组为31名不受全身振动危害的测量工和外线电工,平均年龄321岁,平均工龄107年,两…     

全身振动对人体的影响与防护

本文综述了全身振动对人体所产生的生物动力学效应、生理学效应、病理学效应和心理学效应;提出了对振动环境进行控制、对人体提供保护的原则和方法;从系统工程和优化设计的角度,重点研究、探讨了振动结构动态设计方法在工程实际中的可行性和有效性,为安全、经济、有效地减小振动对人体的不良影响,提高人们日常生活、工作中的舒适性和工作效率以及保证伤病员的安全运送提供了一种途径。     

全身振动对人全肾脏位置的影响

采用ＢＫ振动测量仪器对３４辆机动车振动参数进行了测量，并对２５２名司机和３２１名排振动作业人工的肾脏立卧位活动度进行了Ｂ超检测，发现机动车辆驾驶员肾脏立卧位活动度〉４ｃｍ（肾下垂）者显著高于对照组ＡＲ％６４０６。检出率卡车司机〉客车司机〉对照组，而高年龄组的检查率有所下降，表明全身振动对人体肾脏的正常位置的一定影响，活动度的大小与振动暴露强度，年龄，体重都有关系。     

Effects of Chromium on Body Composition and Weight Loss

Chromium is an essential nutrient involved in the regulation of carbohydrate and lipid metabolism. Normal dietary intake of chromium in humans and farm animals is often suboptimal. In addition to its effects on glucose, insulin, and lipid metabolism, chromium has been reported to increase lean body mass and decrease percentage body fat, which may lead to weight loss in humans. The effects of chromium on body composition are controversial but are supported by animal studies, which increase their validity. A subject's response to chromium depends on his or her chromium status, diet consumed, type and amount of supplemental chromium, and study duration. There have been no confirmed negative effects of chromium in nutritional studies. Chromium is only a small part of the puzzle in the control of weight loss and body composition, and its effects, if present, will be small compared with those of exercise and a well-balanced diet.     

Effects of birth cohort and age on body composition in a sample of community-based elderly

BACKGROUND: The effect of the recent obesity epidemic on body composition remains unknown. Furthermore, age-related changes in body composition are still unclear. OBJECTIVE: The objective was to simultaneously examine the effects of birth cohort and age on body composition. DESIGN: A total of 1786 well-functioning, community-based whites and blacks (52% women and 35% blacks) aged 70-79 y from the Health, Aging, and Body Composition Study underwent dual-energy X-ray absorptiometry annually from 1997 to 2003. RESULTS: At baseline, mean +/- SD percentage body fat, fat mass, and lean mass (bone-free) were 28 +/- 5%, 24 +/- 7 kg, and 56 +/- 7 kg, respectively, for men and 39 +/- 6%, 28 +/- 9 kg, and 40 +/- 6 kg for women. Mixed models were used to assess the effects of cohort and age-related changes on body composition. Later cohorts in men had a greater percentage body fat (0.32% per birth year, P < 0.0001) than did earlier cohorts. This cohort effect was due to a greater increase in fat mass than in lean mass (0.45 kg and 0.17 kg/birth year, respectively). With increasing age, percentage body fat in men initially increased and then leveled off. This age-related change was due to an accelerated decrease in lean mass and an initial increase and a later decrease in fat mass. Similar but less extreme effects of cohort and age were observed in women. CONCLUSIONS: The combination of effects of both birth cohort and age leads to bigger body size and less lean mass in the elderly.     

Changes in body composition of cancer patients following combined nutritional support

The effects of combined nutritional support (parenteral, enteral, and oral) were measured in cancer patients unable to maintain normal alimentation. Changes in body composition were quantified by measurement of total body levels of nitrogen, potassium, water, and fat. The protein‐calorie intake of the patients was also evaluated by dietary survey (4‐day recall). Standard anthropometric and biochemical measurements for nutritional assessment were obtained for comparison.

The dietary evaluation indicated that the dietary supplementation for all patients was more than adequate to meet their energy requirements. Almost all patients gained weight on the combined nutritional support regimens. Determination of body composition indicated that change in body weight was equal to the sum of the changes in body protein, total body water, and total body fat. The findings from the anthropometric nutrition indices (arm muscle circumference and triceps skinfold) were consistent with the results of the body composition study.

Information on the nature of the tissue gained was obtained by comparison of body composition data with the ratio of protein:water:lean body mass for normal tissue. The mean gain of protein in the cancer patients was quite small (0.3–0.6 kg). The main change in body weight appeared to be the result of gains in body water and body fat. The total body nitrogen to potassium ratio served to define the extent of tissue anabolism following hyperalimenlation. The ratio dropped in the cancer patients following hyperalimentation toward the value of the control subjects on ad libidum diets. The body compartment techniques described have demonstrated their usefulness in determining the effects of hyperalimentation on cancer patients.     

Changes in body composition of cancer patients following combined nutritional support

The effects of combined nutritional support (parenteral, enteral, and oral) were measured in cancer patients unable to maintain normal alimentation. Changes in body composition were quantified by measurement of total body levels of nitrogen, potassium, water, and fat. The protein-calorie intake of the patients was also evaluated by dietary survey (4-day recall). Standard anthropometric and biochemical measurements for nutritional assessment were obtained for comparison. The dietary evaluation indicated that the dietary supplementation for all patients was more than adequate to meet their energy requirements. Almost all patients gained weight on the combined nutritional support regimens. Determination of body composition indicated that change in body weight was equal to the sum of the changes in body protein, total body water, and total body fat. The findings from the anthropometric nutrition indices (arm muscle circumference and triceps skinfold) were consistent with the results of the body composition study. Information on the nature of the tissue gained was obtained by comparison of body composition data with the ratio of protein:water:lean body mass for normal tissue. The mean gain of protein in the cancer patients was quite small (0.3-0.6 kg). The main change in body weight appeared to be the result of gains in body water and body fat. The total body nitrogen to potassium ratio served to define the extent of tissue anabolism following hyperalimentation. The ratio dropped in the cancer patients following hyperalimentation toward the value of the control subjects on ad libidum diets. The body compartment techniques described have demonstrated their usefulness in determining the effects of hyperalimentation on cancer patients.     

The influences of ambient and body calcium on cadmium and zinc accumulation in Daphnia magna

The dissolved uptake rate constant (k(u)), dietary assimilation efficiency (AE), and efflux rate constant (k(e)) of cadmium (Cd) and zinc (Zn) were quantified in a freshwater zooplankton Daphnia magna cultured at different ambient calcium (Ca) concentrations. The animals were first acclimated to different ambient Ca levels for 7 d from birth before the biokinetic measurements at corresponding Ca levels. With increasing ambient Ca level from 0.5 to 200 mg/L, the body Ca content increased from 0.91% (as tissue dry wt) to 3.75%. The k(u) for Cd decreased by nine times; for Zn it decreased by 2.6 times; and the AE decreased from 62 to 19% and from 46 to 24% for Cd and Zn, respectively. In contrast, Ca levels did not affect significantly the efflux rates of Cd and Zn. The effects of ambient and body Ca levels were separated by measuring the biokinetic parameters in both low--(0.5 mg/L) and high--(50 mg/L) Ca environments using the daphnids containing different body Ca levels. Ambient and body Ca levels had synergistic inhibitory effects on the AEs of Cd and Zn; however, the protective effects against dissolved uptake of Cd and Zn were explained fully by the effects of ambient Ca. The body Ca either had no significant effect (for Cd) or stimulative effects (for Zn). Multiphase biokinetic modeling using the measured parameters gave reasonable predictions of the body burdens of Cd and Zn in different Ca environments. Our results better explain the role of ambient and body Ca in the accumulation of Cd and Zn in D. magna.     

Social Media Use,Body Image,and Psychological Well-Being: A Cross-Cultural Comparison of Korea and the United States

This study examined the relationships among social media use for information, self-status seeking and socializing, body image, self-esteem, and psychological well-being, and some cultural effects moderating these relationships. Americans (n = 502) and Koreans (n = 518) completed an online survey. The main findings showed that (a) social media use for information about body image is negatively related to body satisfaction in the United States and Korea, while social media use for self-status seeking regarding body image is positively related to body satisfaction only in Korea; and (b) body satisfaction has direct and indirect positive effects on psychological well-being manifested in similar ways in the United States and Korea. Implications and future research directions are discussed.     

0～16岁城乡儿童骨骼矿物质含量及影响因素的研究

使用单光子骨矿物测定仪，自１９９４年初到１９９５年底，分别在河南省扶沟县和新乡市测定了３３２名健康的０～１６岁城乡儿童右前臂１／３处桡骨和尺骨的骨矿物质含量（ＢＭＣ），采用逐步多元回归分析了多个独立变量对桡骨ＢＭＣ和测量部位骨宽度的影响。结果显示：桡骨和尺骨的ＢＭＣ、骨宽度（ＢＷ）、ＢＭＣ／ＢＷ和前臂长度均随年龄而增加，０～６岁城市儿童的ＢＭＣ高于农村儿童；桡骨ＢＭＣ与所测量部位的ＢＷ呈正相关，年龄、体重和身高对桡骨ＢＭＣ都显示出显著和独立的正影响；儿童的桡骨ＢＭＣ与年龄呈显著正相关；而桡骨ＢＭＣ与体重的比值与年龄呈显著负相关；测定部位桡骨ＢＷ和前臂长度随年龄的增加呈曲线增加。在以身高和体重调整后，性别、年龄和体重对桡骨ＢＷ的影响变得不显著，只有身高的影响显著。本研究证明儿童在０～１６岁范围，身高（而不是肥胖）是骨骼ＢＭＣ的主要决定因素。在比较儿童骨密度结果时，要参考多个变量，如ＢＭＣ、骨密度，ＢＭＣ／体重、ＢＭＣ／年龄等综合评价指标更有说明力。     

The effects of exercise on food intake and body fatness: a summary of published studies

Exercise has well-recognized health benefits, including reduction in risk factors for cardiovascular disease and type 2 diabetes. However, the extent to which exercise influences energy regulation and facilitates a reduction in body fat is less clear. This review summarizes published studies on the effects of different amounts of exercise on body fatness, energy intake, and food preferences in humans. The results show consistent effects of exercise on body fatness in the absence of prescribed dietary change, with a progressive loss of body fat associated with higher exercise energy expenditures in both men and women. In part, these effects appear to be mediated by a spontaneous reduction in hunger associated with participation in exercise. Insufficient data are available on whether there are changes in food preferences and taste perception that influence energy balance through macronutrient selection, so further studies in this area are needed.     

青少年学生体像烦恼与自尊的相关研究

目的研究青少年学生体像烦恼与自尊的关系,为制定教育对策提供理论依据。方法采用自编的《青少年学生体像烦恼问卷》和Rosenberg的《自尊量表》对随机抽取的2981名大、中学生进行调查。结果青少年学生总体像烦恼及4个具体方面与自尊都呈显著负相关,有体像烦恼的男生自尊得分显著低于女生;有体像烦恼的大学生自尊得分显著低于高中生,城市学生的自尊得分显著低于农村学生;青少年学生肥胖指数与自我对体重的主观认识呈显著正相关,肥胖指数与自我体重认识一致与不一致者的自尊得分差异无统计学意义。结论青少年学生体像烦恼对其自尊的影响会随着年龄的增长而减少;在进行青少年学生体像教育时,要注意体像烦恼对整体自我价值感的负面影响。     

Media-portrayed idealized images, body shame, and appearance anxiety

OBJECTIVE: This study was designed to determine the effects of media-portrayed idealized images on young women's body shame and appearance anxiety, and to establish whether the effects depend on advertisement type and on participant self-objectification. METHOD: Participants were 39 female university students. Twenty-four magazine advertisements comprised 12 body-related and 12 non-body-related products, one half of each with, and the other one half without, idealized images. Preexposure and post exposure body shame and appearance anxiety measures were recorded. RESULTS: Appearance anxiety increased after viewing advertisements featuring idealized images. There was also a significant interaction between self-objectification level and idealized body (presence vs. absence). No differences emerged for body-related compared with non-body-related product advertisements. The only result for body shame was a main effect for time. Participants' body shame increased after exposure to idealized images, irrespective of advertisement type. DISCUSSION: Although our findings reveal that media-portrayed idealized images detrimentally affect the body image of young women, they highlight the individual differences in vulnerability and the different effects for different components of body image. These results are discussed in terms of their implications for the prevention and early intervention of body image and dieting-related disorders. (