排序方式: 共有50条查询结果,搜索用时 453 毫秒
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LoSecco JM Bionta RM Biewitt G Bratton CB Casper D Chrysicopoulou P Claus R Cortez BG Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Haines TJ Jones TW Kielczewska D Kropp WR Learned JG Lehmann E Park HS Reines F Schultz J Seidel S Shumard E Sinclair D Sobel HW Stone JL Sulak L Svoboda R van der Velde JC Wuest C 《Physical review letters》1985,54(21):2299-2301
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John?F?StinsEmail author G?Caroline?M?van Baal Tinca?JC?Polderman Frank?C?Verhulst Dorret?I?Boomsma 《BMC neuroscience》2004,5(1):49
Background
There is great interest in appropriate phenotypes that serve as indicator of genetically transmitted frontal (dys)function, such as ADHD. Here we investigate the ability to deal with response conflict, and we ask to what extent performance variation on response interference tasks is caused by genetic variation. We tested a large sample of 12-year old monozygotic and dizygotic twins on two well-known and closely related response interference tasks; the color Stroop task and the Eriksen flanker task. Using structural equation modelling we assessed the heritability of several performance indices derived from those tasks. 相似文献6.
Sakari Leino Patrick JC May Paavo Alku Lassi A Liikkanen Hannu Tiitinen 《BMC neuroscience》2007,8(1):78
Background
In the field of auditory neuroscience, much research has focused on the neural processes underlying human sound localization. A recent magnetoencephalography (MEG) study investigated localization-related brain activity by measuring the N1m event-related response originating in the auditory cortex. It was found that the dynamic range of the right-hemispheric N1m response, defined as the mean difference in response magnitude between contralateral and ipsilateral stimulation, reflects cortical activity related to the discrimination of horizontal sound direction. Interestingly, the results also suggested that the presence of realistic spectral information within horizontally located spatial sounds resulted in a larger right-hemispheric N1m dynamic range. Spectral cues being predominant at high frequencies, the present study further investigated the issue by removing frequencies from the spatial stimuli with low-pass filtering. This resulted in a stepwise elimination of direction-specific spectral information. Interaural time and level differences were kept constant. The original, unfiltered stimuli were broadband noise signals presented from five frontal horizontal directions and binaurally recorded for eight human subjects with miniature microphones placed in each subject's ear canals. Stimuli were presented to the subjects during MEG registration and in a behavioral listening experiment. 相似文献7.
Recently, Nielsen et al. [J. Chem. Phys. 130, 154508 (2009); Philos. Mag. 88, 4101 (2008)] demonstrated a universal pattern for the high frequency wing of the loss curve for primary relaxation time on approaching the glass transition for organic liquids. In this contribution it is presented that a similar universality occurs for glass-forming liquid crystals and orientationally disordered crystals (plastic crystals). Empirical correlations of the found behavior are also briefly discussed. 相似文献
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Abstract A synchrotron X-ray diffraction study on hexagonal graphite-like boron nitride (h-BN) was performed under high pressures and temperatures. From the measured P-V-Trelation for h-BN (with a three-dimensional ordering parameter P3 = 0.9) in the temperature range from 298 to 1273 K and up to 6.7 GPa, the thermoelastic parameters are derived by fitting a modified high temperature Birch-Murnaghan equation of state. The results are: bulk modulus B0[GPa] = 27.6-0.0081(T[K]-298) and its pressure derivative B1 = 10.5 + 0.0016(T [K] - 298). These values are for samples with P3 = 0.9 and are quite different for samples with different values of the order parameter. This parameter is shown to have a leading role in the determination of the thermoelastic properties of h-BN, which explains and reconciles the differences between previous results. 相似文献
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DC Muddiman AP Null JC Hannis 《Rapid communications in mass spectrometry : RCM》1999,13(12):1201-1204
Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) has been used to determine the mass of a double-stranded 500 base-pair (bp) polymerase chain reaction (PCR) product with an average theoretical mass of the blunt-ended (i.e. unadenylated) species of 308 859.35 Da. The PCR product was generated from the linearized bacteriophage Lambda genome which is a double-stranded template. Utilization of ethanol precipitation in tandem with a rapid microdialysis step to purify and desalt the PCR product was crucial to obtain a precise mass measurement. The PCR product (0.8 pmol/μL) was electrosprayed from a solution containing 75% acetonitrile, 25 mM piperidine, and 25 mM imidazole and was infused at a rate of 200 nL/min. The average molecular mass and the corresponding precision were determined using the charge-states ranging from 172 to 235 net negative charges. The experimental mass and corresponding precision (reported as the 95% confidence interval of the mean) was 309 406 +/- 27 Da (87 ppm). The mass accuracy was compromised due to the fact that the PCR generates multiple products when using Taq polymerase due to the non-template directed 3'-adenylation. This results in a mixture of three PCR products with nearly identical mass (i.e. blunt-ended, mono-adenylated and di-adenylated) with unknown relative abundances that were not resolved in the spectrum. Thus, the experimental mass will be a weighted average of the three species which, under our experimental conditions, reflects a nearly equal concentration of the mono- and di-adenylated species. This report demonstrates that precise mass measurements of PCR products up to 309 kDa (500 bp) can be routinely obtained by ESI-FTICR requiring low femtomole amounts. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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This paper introduces Cárnico-ICSPEA2, a metaheuristic co-evolutionary navigator designed by its end-user as an aid for the analysis and multi-objective optimisation of a beef cattle enterprise running on temperate pastures and fodder crops in Chalco, Mexico State, in the central plateau of Mexico. By combining simulation routines and a multi-objective evolutionary algorithm with a deterministic and stochastic framework, the software imitates the evolutionary behaviour of the system of interest, helping the farm manager to ‘navigate’ through his system’s dynamic phase space. The ultimate goal was to enhance the manager’s decision-making process and co-evolutionary skills, through an increased understanding of his system and the discovery of new, improved heuristics. This paper describes the numerical simulation and optimisation resulting from the application of Cárnico-ICSPEA2 to solve a specific multi-objective optimisation problem, along with implications for the management of the system of interest. 相似文献