Takamasa Koyama

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The behavioral development of a malformed male infant in a free-ranging Japanese monkey group, whose hands were completely missing and whose hind feet were distorted, was investigated during the first one year of life, by comparison with normal infants. In the first few weeks of life, the malformed infant was not able to move by himself and was almost(More)
Bisphenol A (BPA) is an environmental chemical with physiological potencies that cause adverse effects, even at environmentally relevant exposures, on the basis of a number of studies in experimental rodents. Thus, there is an increasing concern about environmental exposure of humans to BPA. In the present study, we used experimentally controlled cynomolgus(More)
We propose a parallel two-step phase-shifting digital holography technique capable of instantaneous measurement of three-dimensional objects, with a view toward measurement of dynamically moving objects. The technique is based on phase-shifting interferometry. The proposed technique carries out the two-step phase-shifting method at one time and can be(More)
Make-up may enhance or disguise facial characteristics. The influence of wearing make-up on facial recognition could be of two kinds: (i) when women do not wear make-up and then are seen with make-up, and (ii) when women wear make-up and then are seen without make-up. A study is reported which shows that light make-up makes it easier to recognise a face,(More)
Bisphenol A (BPA) is a widespread environmental contaminant, and humans are routinely exposed to BPA. We investigated whether prenatal exposure to BPA influences behavioral development in juvenile cynomolgus monkeys (Macaca fascicularis). Pregnant cynomolgus monkeys were implanted with subcutaneous pumps and exposed to 10μg/kg/day BPA or vehicle (control)(More)
The authors propose an optical-path-length-shifting digital holography as a technique capable of single-shot recording of three-dimensional information of objects. With a single image sensor, the proposed technique can simultaneously record all of the holograms required for the in-line digital holography that reconstruct the image of an object from two(More)
Pregnant rhesus monkeys (Macaca mulatta) were exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at 30 and 300 ng/kg by subcutaneous injection at gestational day 20, followed by additional injections of TCDD (1.5 and 15 ng/kg, respectively) every 30 days till 90 days after parturition. The offspring delivered from these experimentally TCDD-exposed(More)
In order to easily estimate the global cognitive ability of nonhuman primates, we developed a 4-step noncorrection-method-type finger maze (4FM) based on the standard puzzle feeder. We tested 7 experimentally naïve long-tailed macaques (Macaca fascicularis) to assess the validity of the apparatus and the testing procedure. The most notable difference(More)
Polychlorinated biphenyls (PCBs) are endocrine disrupting chemicals that disturb normal development of embryonic brains. In the present study, we evaluated the relationship between maternal plasma PCB concentration and infant behavioral characteristics in mother-infant interactions. We grouped 20 pregnant cynomolgus monkeys (Macaca fascicularis) into higher(More)
The psychological stress was evaluated in repeated and unrepeated procedures of weaning as well as forming peer group in squirrel monkeys. The repeated procedure included the process of increasing the period of separation or formation stepwise during four weeks. The plasma cortisol levels and natural killer (NK) activities were monitored during experiment(More)