Sexuality education and young people's sexual behavior: a review of studies

Sexuality education for children and young adults is one of the most heavily debated issues facing policy-makers, national AIDS program planners, and educators, provoking arguments over how explicit education materials should be, how much of it there should be, how often it should be given, and at what age instruction should commence. In this context, the World Health Organization's Global Program on AIDS' Office of Intervention Development and Support commissioned a comprehensive literature review to assess the effects of HIV/AIDS and sexuality education upon young people's sexual behavior. 52 reports culled from a search of 12 literature databases were reviewed. The main purpose of the review is to inform policy-makers, program planners, and educators about the impact of HIV and/or sexuality education upon the sexual behavior of youth as described in the published literature. Of 47 studies which evaluated interventions, 25 reported that HIV/AIDS and sexuality education neither increased nor decreased sexual activity and attendant rates of pregnancy and sexually transmitted diseases (STDs). 17 reported that HIV and/or sexuality education delayed the onset of sexual activity, reduced the number of sex partners, or reduced unplanned pregnancy and STD rates Only 3 studies found increases in sexual behavior associated with sexuality education. Inadequacies in study design, analytic techniques, outcome indicators, and the reporting of statistics are discussed.     

The effects of periodic visual occlusion on ball catching

Four experiments were conducted to examine the effects of periodic visual occlusion on one-handed ball catching. Tennis balls were projected one at a time over distances of 8-12 m, and liquid-crystal visual occlusion spectacles provided intermittent vision by opening and closing the lens shutters at different frequencies. As well as frequency, we manipulated duty cycle, or the proportion of time that the lenses were open. Generally, catching performance deteriorated as frequency was reduced. Although longer visual samples (i.e., increased duty cycle) mediated this effect to some extent, the most potent variable was the time between visual samples; performance deteriorated rapidly when this interval was greater than 80 ms (i.e., 10 Hz with 20-ms lens open times). Presumably this occurred because subjects had difficulty integrating visual information separated by longer temporal intervals.     

Partial visual feedback and spatial end-point accuracy of discrete aiming movements

Five experiments are reported in which the effect of partial visual feedback on the accuracy of discrete target aiming was investigated. Visual feedback was manipulated through a spectacle-mounted liquid-crystal tachistoscope. The length of the visual feedback interval was varied as a percentage of the instructed movement time. In Experiment 1, the length of the vision interval was manipulated symmetrically at the beginning- and end-phase of the movement, whereas in the remaining experiments, the vision time was varied with respect to the end-phase only. The variations at the end were examined for different distances (Experiment 2), different movement speeds at the same distance (Experiment 3), and in small interstep intervals (Experiment 4). A vision time of more than 150 ms at the end-phase of the movement enhanced aiming performance in all experiments. Longer vision times monotonously improved aiming accuracy; the fifth experiment showed that a vision time of about 275 ms was sufficient for near-perfect aiming. Furthermore, the significance of vision during the first phase of a movement was demonstrated again. The results of the five experiments pointed to shorter visuomotor processing times. To explain the beneficial effects of short vision times for aiming accuracy, we propose a model of visuomotor processing that is based on the stochastic optimized submovement model of Meyer, Abrams, Kornblum, Wright, and Smith (1988).     

2001年的科学哲学

一种民主制度的最重要也是讨论最少的任务之一就是要保护它的成员免遭这种制度中的意识形态的伤害.必须正确地看待所有的意识形态.人们必须把它们当作神话故事来看待,它们能告诉人很多有趣的事,但也包含了很多谬误和令人生厌的谎言.当人们按照某一观点行动时,他们的态度也应该像密探一样,为了在一个陌生的国家里获得成功而采纳它的信仰并在细枝末节上按照这些信仰去做,但并不全盘接受.这一点适用于所有的信仰,适用于基督教上帝的存在这一信仰,适用于所有的人生来平等的信仰,也适用于科学.那么,这是否是一种陌生和荒谬的态度呢?科学当然总是处在与权威主义和迷信战斗的前沿.相对于宗教信仰而言,我们有了越来越大的思想自由,这应当归功于科学;人类从古代的僵硬思维方式中解放出来,也应当归功于科学.今天,这些思维方式仅仅是一些糟糕的     

Savings and fertility: ethical issues

... Population ethics is rightly regarded a difficult field of inquiry. Here I have tried to argue that the kinds of difficulty that have intrigued philosophers in recent years are insubstantial. Real difficulties lie elsewhere. They lie in deep conceptual problems actual people are faced with when they contemplate the desirable size of their family and the savings that should accompany it.     

Temporal discrimination learning of operant feeding in goldfish (Carassius auratus)

Operant temporal discrimination learning was investigated in goldfish. In the first experiment, there was a fixed daily change in illumination. Eight subjects were trained to operate a lever that reinforced each press with food. The period during which responses were reinforced was then progressively reduced until it was 1 hr in every 24. The final 1-hr feeding schedule was maintained over 4 weeks. The feeding period commenced at the same time each day throughout. The food dispensers were then made inactive, and a period of extinction ensued for 6 days. The pattern of responding suggested that the fish were able to exhibit temporal discrimination in anticipation of feeding time. This pattern of responding persisted for a limited number of days during the extinction procedure. The second experiment produced evidence that operant temporal discrimination could develop under continuous illumination.     

现实化的可能体与最简的量化模态逻辑

现实论(actualism)这项方案,旨在清除逻辑与模态形而上学中那些讨人嫌的本体论承诺。它从一切存在的都是现实的这个观点出发,试图重新解释语言,以避免承诺“可能体”(possibilia)的存在。所谓“可能体”,指那些可能的,但非现实的对象。量化模态逻辑(QML)似乎就要求这种对象存在。最简QML为古典量化理论与模态命题逻辑之合并,可是它使巴康(Barcan)公式(今日x由→ax令Q)有效。从而,由可能存在一头会说话的驴子这个事实,就推出了存在某物,它可能是一头会说话的驴子。这看起来在宣称一个可能实体的存在(假定每个现实的东西都不可能是会说话的驴子)。现实论者们大力主张克里普克(Kripke)所描述的语义学,以此来免除这项承诺,这种语义学采用了可变论域,因而使巴康公式归于无效。     

生命保护的推断论理由

推断论伦理学家就堕胎和安乐死的问题而提出的命题,主要是澳大利亚人P.辛格的那些命题,一直引起激烈的论战。推断论将生命保护理解为一种利益保护,它使个体的生命权利依赖于成为人的那种特性。按照推断论的观点,不是所有人类的个体都是人,因而就不能赋予非—个人的人类个体以生命权利——这在实践中是有相应的结果的。不管对P.辛格的命题在感情上的反应多么可以理解,光靠这些命题是得不到什么结果的,因为重要的是研究这些命题所引用的证据,研究那些已经决定了推断论的问题表述的前概念。只要推断论的潜在的前题不受到怀疑,人们也许将无法摆脱单纯的口头侮辱。     

世界各种宗教与世界宗教

宗教非常重要 宗教关注整个生命的终极价值,是涉及人类的非常重大的事情。 宗教起团结作用 宗教起团结联合的作用,但宗教一多则起分裂作用。因为各种宗教是分裂的,这对宗教来说是有害的。 传统的区分或分割 每一传统文化均建立它关于生命本质及其价值的原则,并且传授这些原则,使之成为人们的行为规范,因为人们相信这些原则是正确的。但是早期产生的关于生命与价值的信念,缺乏足够的知识,只是因为人们信以为真而且非常重要,这些信念便被视为神圣不可侵犯,是生命不可或缺的。这些原则在孤立环境中,甚至解释力不强时,也还可能使人们获得幸福。但当人们与其他传统的原则与实践发生冲突,另一种传统威胁到他们自己传统时,每个人都相信自己的传统正确而另一种传统错误,他一定会设法反对它。