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211.
Discusses neurological development underlying the emergence of symmetrical optokinetic nystagmus (OKN). During early infancy and following visual deprivation early in life, humans show asymmetrical OKN that is likely due to nonfunctioning projections through the visual cortex to the midbrain. However, the ability of the newborn to discriminate shape, orientation, and color suggests that some part of the geniculo-striate pathway is functional at birth. Limitations may be due to immaturities in the magnocellular pathway; abilities appear to be mediated by the parvocellular pathway, in conjunction with direct projections to other areas of the midbrain. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
212.
Several species of snakes aggregate in areas previously marked by conspecifics. However, species differences and sources of such chemical signals have received little attention. Methylene chloride-soluble substances from shed epidermis of adult plains garter snakes attracted neonate conspecifics, whereas similar extracts from a congener and a viperid did not. The functional significance of such conspecific aggregation may relate to location of hibernacula, foraging areas, osmoregulation, or predation avoidance. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
213.
Junwu Zhao Jan S. Koontz Brent L. Adams 《Metallurgical and Materials Transactions A》1988,19(5):1179-1185
The intercrystalline structure distribution function (ISDF) describes the probability density for the occurrence of grain
boundaries in the polycrystalline medium with five specified geometrical parameters: three describing intercrystalline lattice
misorientation and two describing the orientation of the grain boundary plane. This paper extends the ISDF analysis to Bunge’s
formalism which represents the distribution in terms of a series expansion of symmetric generalized spherical harmonics. An
exemplary calculation of the ISDF is illustrated for alloy 304 stainless steel tubing. The results confirm the observation
that gS3 and gS9 boundaries, arising from twinning, are prevalent in the structure. The distribution of twinning boundaries
and other special boundaries is represented by Euler plots in the five geometrical parameters defining boundary structure.
One remarkable feature of this material is a nearly isotropic distribution of boundary misorientation in the two parameters
defining the boundary plane orientation. These results are compared with other published experimental data and theoretical
calculations for the distribution of special boundaries. 相似文献
214.
Roberts Brent W.; Walton Kate E.; Viechtbauer Wolfgang 《Canadian Metallurgical Quarterly》2006,132(1):1
The present study used meta-analytic techniques (number of samples = 92) to determine the patterns of mean-level change in personality traits across the life course. Results showed that people increase in measures of social dominance (a facet of extraversion), conscientiousness, and emotional stability, especially in young adulthood (age 20 to 40). In contrast, people increase on measures of social vitality (a 2nd facet of extraversion) and openness in adolescence but then decrease in both of these domains in old age. Agreeableness changed only in old age. Of the 6 trait categories, 4 demonstrated significant change in middle and old age. Gender and attrition had minimal effects on change, whereas longer studies and studies based on younger cohorts showed greater change. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
215.
I. Brent Heath 《Journal of microscopy》1984,135(1):75-82
A liquid helium cooled copper block device has been designed for the rapid freezing of biological material. The apparatus differs from previous designs in being easily constructed from readily available components. It incorporates a novel and simplified specimen carrying system. Construction of this apparatus is possible for any laboratory and makes the advantages of freeze substitution reliably available for many cell types at minimal cost. 相似文献
216.
Nutrient simulations of a municipal wastewater land treatment system were performed using the ground-water loading effects of agricultural management systems model. A total of 33 best management practices (BMPs) were simulated and compared to a baseline simulation of the current reed canary grass management practice. BMPs consisted of various combinations of crop types and cropping practices. Effectiveness of BMPs was compared based on the amount of nitrogen leached through the root zone and the harvested market value of each crop. Based on the model predictions and local market conditions, recommendations for the facility were given as the following: reed canary grass cut four times per year, orchard grass cut three or four times per year, or silage corn with a winter cover crop under low wastewater loading. Overloading the reed canary grass and orchard grass, especially for short periods of time, was simulated to have no adverse effects on the ground water. The ground-water loading effects of agricultural management systems model was demonstrated as a useful tool for the optimization of a municipal wastewater land treatment facility. 相似文献
217.
We have applied real time spectroscopic ellipsometry and secondary ion mass spectrometry to study the growth of amorphous silicon by hot-wire chemical vapor deposition. Differences in temperature and hydrogen content affect the optical properties of the film. These effects provide valuable insight into the growth process. We have compared a-Si:H films grown at two different temperatures to better understand these effects. Our studies reveal the presence of a distinct 100–200-thick layer at the top of the growing film. The properties of this layer are primarily determined by the ambient conditions in the growth chamber and appear relatively independent of substrate temperature. In contrast, the properties of the bulk of the film are strongly influenced by substrate temperature. These results imply that differences in film properties associated with substrate temperature are the result of subsurface reconstruction and diffusion processes. 相似文献
218.
Christian Struebing Meredith Brooke Beckert Jason H. Nadler Bernd Kahn Brent Wagner Zhitao Kang 《Journal of the American Ceramic Society》2018,101(3):1116-1121
A transparent gadolinium‐rich oxyhalide glass scintillator was developed for gamma ray spectroscopy with an energy resolution of 14.0% at 662 keV. To the best of our knowledge, this is the highest energy resolution reported for a glass‐based scintillator. The high gadolinium content facilitated a scintillator density of 4.4 g/cm3. The high fluorine and bromine incorporation is advantageous for better uniformity and a good light output of ~3200 Ph/MeV. The peak emission at 431 nm with a FWHM of 90 nm, resulting from the fast Ce3+ transitions, yielded pulse‐height spectra with distinctive peaks from 122 keV to 1.33 keV for gamma radiation from different nuclides. 相似文献
219.
Ahmed Elwakil Brent Maundy Mohammed Balla Elamien Leonid Belostotski 《Analog Integrated Circuits and Signal Processing》2018,95(1):173-179
We propose a four quadrant six transistor current multiplier cell based on the translinear principle. The cell is further modified by using resistive feedback to remove two PNP transistors hence reducing the total transistor count to four NPN transistors only. This not only eliminates the problem of mismatch between the two transistor types but allows the cell to operate both as a current multiplier/divider depending on the resistive feedback ratio. The modified cell can also multiply mixed current/voltage signals and operates equally well with NMOS transistors instead of bipolar ones. Experimental results using discrete transistors confirming the correct operation of the cell are provided. 相似文献
220.
This paper reports the results of two experiments investigating differences in comprehensibility of textual and graphical notations for representing decision statements. The first experiment was a replication of a prior experiment that found textual notations to be better than particular graphical notations. After replicating this study, two other hypotheses were investigated in a second experiment. Our first claim is that graphics may be better for technical, non-programmers than they are for programmers because of the great amount of experience that programmers have with textual notations in programming languages. The second is that modifications to graphical forms may improve their usefulness. The results support both of these hypotheses. 相似文献