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A series of experiments examined the abilities of infants to form categorical representations for the spatial relations above and below. Exp 1 provided evidence that 3–4 mo olds can form categorical representations for above and below when a diamond shape was presented above or below a horizontal bar. Exps 2 and 3 showed that 3- and 4-mo olds did not form categorical representations for above and below when a number of discriminably different shapes (e.g., a diamond, a triangle, a dot) appeared above or below the bar. These more abstract categorical representations for above and below were formed by 6- to 7-mo olds (Exp 4). The findings suggest an experientially or maturationally based trend, from concrete to abstract, in the categorical representation of common spatial relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
3.
This paper describes a method for the design of discrete-time model matching control systems for a multivariable plant with measurement noise. This method uses a new parametrization for model matching controllers. Simulation results are presented which confirm the validity of the design method  相似文献   
4.
The influence of transient circulatory arrest on the healing of closed tibial fractures was investigated in rats by the use of a hindlimb tourniquet technique. Twenty-four animals were randomly divided into three groups. In all animals, the left lower leg was fractured and fixed with an intramedullary nail system. In the ischemic group, complete acute transient ischemia for 4.5 h and neurapraxia of the sciatic and femoral nerves were induced prior to fracture. In the neurapraxia group, the sciatic and femoral nerves were crushed with forceps before fracture. In the control group, no other intervention than fracture was made. The rats of the control group ambulated normally 3-4 days after the operation. The animals of the ischemic and neurapraxia groups resumed normal weight-bearing after about 3 weeks. After 6 weeks, all animals were killed, and mechanical strength and bone mineral turnover of the healing tibia as well as blood flow of the bone and musculature were evaluated. The weight of the tibia and the corresponding anterior tibial muscle in the ischemic and neurapraxia animals were reduced compared with the control rats. Bone mineral turnover was found to be lower in the ischemic group. There were no differences between the groups in mechanical strength nor in blood circulation of bone and muscle. In conclusion, complete, acute hindlimb ischemia for 4.5 h in rats did not cause delayed healing of closed tibial fractures.  相似文献   
5.
The angular distribution of K-REC for 45.7 and 51.9 MeV Ar4+ + C has been measured and found to be consistent with sin2θlab.  相似文献   
6.
A drive-current enhancement in NMOS with a compressively strained SiGe structure, which had been a difficult challenge for CMOS integration with strained SiGe high-hole-mobility PMOS, was successfully achieved using a Si-SiGe heterostructure low electric field channel of optimum thickness. A 4-nm-thick Si low-field-channel NMOS with a 4-nm-thick Si/sub 0.8/Ge/sub 0.2/ layer improved drive current by 10% with a 20% reduction in gate leakage current compared with Si-control, while suppressing threshold-voltage rolloff characteristic degradation, and demonstrated excellent I/sub on/--I/sub off/ characteristics of I/sub on/ = 1 mA//spl mu/m for I/sub off/ = 100 nA//spl mu/m. These results are the best in ever reported NMOS with a compressively strained SiGe structure and indicate that a Si-SiGe heterostructure low-field-channel NMOS integrated with a compressively strained SiGe channel PMOS is a promising candidate for high-speed CMOS in 65-nm node logic technology.  相似文献   
7.
The partial sequences of the mitochondrial (mt) cytochrome b gene (402 bp) were determined for species of Aspergillus section Flavi. On the basis of identities of DNA sequences, 77 strains were divided into seven DNA types, from D-1 to D-7. The type strains of A. sojae, A. parasiticus, A. flavus and A. oryzae together, A. tamarii, and A. nomius were placed in DNA types D-1. D-2, D-4, D-5 and D-7, respectively. These species could be differentiated from each other. Furthermore, two other DNA types, D-3 and D-6 were found. DNA type D-3 was closely related to A. parasiticus (D-2) and included one strain that deposited as A. flatus var. flavus and produced aflatoxins B and G. DNA types D-6 included one strain named A. flavus and closely related to A. tamarii. The observations of conidial wall texture by SEM (Scanning Electron Microscopy) supported the relationships derived from the cytochrome b gene. The production of aflatoxins was also examined. Using the DNA sequence of cytochrome b gene, several strains were reidentified. The derived amino acids sequences were all the same in the studied strains. The mt cytochrome b gene is useful and reliable in distinguishing and identifying the species in Aspergillus section Flavi.  相似文献   
8.
Meiotic recombination of S. cerevisiae contains two temporally coupled processes, formation and processing of double-strand breaks (DSBs). Mre11 forms a complex with Rad50 and Xrs2, acting as the binding core, and participates in DSB processing. Although these proteins are also involved in DSB formation, Mre11 is not necessarily holding them. The C-terminal region of Mre11 is required only for DSB formation and binds to some meiotic proteins. The N-terminal half specifies nuclease activities that are collectively required for DSB processing. Mre11 has a DNA-binding site for DSB formation and another site for DSB processing. It has two regions to bind to Rad50. Mre11 repairs methyl methanesulfonate-induced DSBs by reactions that require the nuclease activities and those that do not.  相似文献   
9.
In a three-phase, three-leg core of a core-type power transformer, the yokes are magnetically connected to all three phases so as to ease the flow of the magnetic flux (generally by means of lap joints of yokes and legs), and at the same time to smooth the magnetic flux between phase legs through yokes. It has generally been assumed that a split core with full separation at the center of the leg including yokes is unsuitable for use in power transformers owing to core losses, local heating, and noise resulting from the imbalance and distortion of magnetic flux, even though it can be used in distribution transformers with wound cores. But since the split core has many advantages from the manufacturing viewpoint, the magnetic characteristics of small core models were studied in detail. Studies with a full-scale 1500/3 MVA model transformer core indicate that the degradation of magnetic characteristics compares favorably with conventional cores.  相似文献   
10.
Vitamin A (VA) deficiency is the leading cause of blindness in children in developing countries. Dietary intervention with foods rich in provitamin A carotenoids, such as beta-carotene (betaC), has been suggested as one solution to this problem. The objective of the two studies described in this paper was to examine the utilization of betaC as a source of VA at different stages of VA depletion using the Mongolian gerbil as a model. Male 4- to 5-wk-old Mongolian gerbils were fed powdered betaC-free semipurified diets either with or without VA for 26 d (Study 1), or without VA for 8-10 wk (Study 2). Gerbils were then fed diets with or without VA (20.9 nmol/g diet) and/or betaC [(67.0 micromol/g diet (Study 1) and 145.9 micromol/g diet (Study 2)] for variable periods. Two (Study 1) or three (Study 2) days before termination of the study, 3-4 gerbils per group were dosed orally with 14C-betaC. Tissues were evaluated for VA and betaC content by HPLC. Liver was extracted with and without saponification to evaluate 14C-betaC and 14C-VA content. The results demonstrate the following: 1) the gerbil is an appropriate animal model to study betaC utilization; 2) 20.9 nmol VA/g diet is more than sufficient for this species; 3) the daily VA utilization rate for this species is calculated to be 3.1 microg/100 g body weight; 4) a highly bioavailable source of betaC at a 6:1 weight ratio of betaC:VA is sufficient to reverse marginal VA status in this model; and 5) a highly bioavailable source of betaC fed between a 6:1 and 13:1 weight ratio to VA provides equivalent VA status as preformed VA in Mongolian gerbils.  相似文献   
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