An fMRI study of magnitude comparison and exact addition in children

By contrast to the adult literature, in which a consistent parietofrontal network for number processing has been identified, the data from studies of number processing in children have been less consistent, probably due to differences in study design and control conditions. Number processing was examined using functional magnetic resonance imaging in 18 right-handed children (8–12 years) from the Cape Coloured community in Cape Town, South Africa, using Proximity Judgment and Exact Addition (EA) tasks. The findings were consistent with the hypothesis that, as in adults, the anterior horizontal intraparietal sulcus (HIPS) plays a major role in the representation and manipulation of quantity in children. The posterior medial frontal cortex, believed to be involved in performance monitoring in more complex arithmetic manipulations in adults, was extensively activated even for relatively simple symbolic number processing in the children. Other areas activated to a greater degree in the children included the left precentral sulcus, which may mediate number knowledge and, for EA, the head of the caudate nucleus, which is part of a fronto-subcortical circuit involved in the behavioral execution of sequences. Two regions that have been linked to number processing in adults — the angular gyrus and posterior superior parietal lobule — were not activated in the children. The data are consistent with the inference that although the functional specialization of the anterior HIPS may increase as symbolic number processing becomes increasingly automatic, this region and other elements of the parietofrontal network identified in adults are already reliably and robustly activated by middle childhood.     

气体钻水平井环空冲蚀能量分析

在建立水平井流动方程的基础上,通过气固两相流动基本数学模型的求解数值模拟不同工况条件下的气固混合物冲蚀能量,得出了冲蚀能量的变化规律。算例数值模拟显示:环空速度剖面主要由注气量大小决定,机械钻速的影响不大;相同注气量条件下,机械钻速降低与井下岩屑浓度等比例下降;注气量的增加能提高井眼净化程度,但不如降低机械钻速效果明显;环空总冲蚀能中气体冲蚀能量占绝对主要地位,岩屑冲蚀能量只占极小部分,在相同注气量条件下总冲蚀能量基本相同;岩屑冲蚀能量主要取决于机械钻速,机械钻速越大井底产生岩屑越多冲蚀能力越强,相同机械钻速条件下,较大注气量能提供较大岩屑运移速度,提高了岩屑冲蚀能量。     

An analytical method for prohexadione in Chinese cabbage and apple

A residual determination method as a regulatory residue method was developed using HPLC‐UVD for prohexadione residues in Chinese cabbage (Brassica pekinensis) and apple (Malus domestica). The developed method consisted of solid–liquid extraction with acidic acetonitrile and ion‐suppression liquid–liquid partitioning, followed by anion exchange cartridge cleanup. The limits of detection and quantitation for the method were 0.005 and 0.02 mg/kg, respectively. The method gave good linearity in the range of 0.02–2.5 mg/kg. Accuracy and precision ranged from 84.1 to 94.1% and from 2.4 to 6.9%, respectively. Additionally, the confirmative conditions of LC‐MS/MS for prohexadione were set in negative electrospray ionization mode with transitions of m/z 211.4 → 167.5 and m/z 211.4 → 123.5 in the selected reaction monitoring mode. The applicability of the method was demonstrated by analyzing real samples collected from local markets in Seoul, Republic of Korea. This developed method fully deserves consideration in accordance with its sensitivity, accuracy and precision required for residue analysis of prohexadione in Chinese cabbages and apples. Copyright © 2010 John Wiley & Sons, Ltd.     

The effect of vertical angular subtense on perception of slant from horizontal size disparity

The slant from horizontal size disparity is geometrically predictable. The apparent slant, however, is usually not equivalent to the prediction as numerous visual factors affect it. The aim of this study is to examine whether the vertical angular subtense of a stimulus with horizontal size disparity alters the magnitude of perceived slant for a given horizontal angular subtense. The results indicate that a smaller angular subtense of display produces a smaller magnitude of slant perception.     

Study of indoor radon and thoron progeny levels in surrounding areas of Nalbari, Assam, India

With the growing understanding of the role of radon and its daughter products as major sources of radiation exposure, the importance of large number of estimation of radon concentration in various parts of the country is realized. Inhalation of radon, thoron and their decay products is the major source of the total radioactive dose received by the human population from natural radiation. The indoor radon and thoron progeny levels in Nalbari area of Assam are studied by using the LR-115 (type II) Solid State Nuclear Track Detector in Plastic Twin Chamber dosimeter. Radon and thoron progeny levels in different types of dwellings for one full calendar year are presented in this paper. For Assam Type (A.T.) houses, indoor radon progeny concentrations vary from 0.17 to 0.64 mWL with an annual geometric mean of 0.27 mWL and that for Reinforced Cement Concrete (R.C.C.) houses vary from 0.22 mWL to 0.60 mWL with the annual geometric mean of 0.37 mWL. The thoron progeny levels in A.T. houses also vary from 0.01 to of 0.05 mWL with an annual geometric mean of 0.02 mWL and that for R.C.C. houses vary from 0.02 to 0.08 mWL with the annual geometric mean of 0.04 mWL.      

A Simple X-ray Spectrometer and PC-based Data Acquisition System for Newly Developed X-ray Source Based on Laser Compton Scattering

A simple X-ray spectrometer and a PC-Based Data Acquisition System(DAS) have been developed newly in Shanghai Institute of Applied Physics(SINAP),Chinese Academy of Sciences (CAS) for the measurement of the X-ray source generated using laser Compton scattering.The system consists of liquid nitrogen cooled high resolution Si(Li) detector,electronics and a DAQ.The Si(Li) detector was designed and made by Center of Advanced Instruments in SINAP,CAS,it allows us to measure X-rays with the energy up to 60 keV and the energy resolution(FWHM) of 184 eV at 5.9 keV.We measured the system uncertainty was 0.2 eV and time drifting of detector was 0.05% both at 5.9 keV.The DAQ was based on Object-Oriented software LabVIEW 7.1,it has data on-line analysis and original data saved functions.     

A Practical Interfacing of HPLC with Electron Capture Detection (HPLC-ECD)

Abstract

Conventional HPLC can be simply, conveniently, and inexpensively interfaced to the electron capture detector within any GC. Various parameters have been evaluated to determine the suitability of this approach for the selective trace analysis of aliphatic and aromatic nitro derivatives.     

Infrared chemical imaging: Spatial resolution evaluation and super-resolution concept

Chemical imaging systems help to solve many challenges in various scientific fields. Able to deliver rapid spatial and chemical information, modern infrared spectrometers using Focal Plane Array detectors (FPA) are of great interest. Considering conventional infrared spectrometers with a single element detector, we can consider that the diffraction-limited spatial resolution is more or less equal to the wavelength of the light (i.e. 2.5-25 μm). Unfortunately, the spatial resolution of FPA spectroscopic setup is even lower due to the detector pixel size. This becomes a real constraint when micron-sized samples are analysed. New chemometrics methods are thus of great interest to overcome such resolution drawback, while keeping our far-field infrared imaging spectrometers. The aim of the present work is to evaluate the super-resolution concept in order to increase the spatial resolution of infrared imaging spectrometers using FPA detectors. The main idea of super-resolution is the fusion of several low-resolution images of the same sample to obtain a higher-resolution image. Applying the super-resolution concept on a relatively low number of FPA acquisitions, it was possible to observe a 30% decrease in spatial resolution.     

Superheated drops of R114—as a neutron spectrometer

The basic principle that has been used in the application of superheated drops in neutron spectrometry is its dependence of threshold energy of nucleation on temperature. In the present work, superheated drops of R114 suspended in a visco-elastic gel were irradiated at different temperatures by neutrons obtained from an ²⁴¹Am–Be source. The temperature of the detector was converted to the energy of the incident neutrons following the method developed by us to unfold the neutron energy spectrum. The threshold energy obtained by us agrees well with other results obtained using monochromatic neutron sources, clearly demonstrating the validity of our principle of spectrometry.     

A New Capillary Electrophoresis Apparatus with Piezoelectric Ceramics High Voltage Source and Amperometric Detector

IntroductionHighperformancecapiliar}'electrophoresis(HPCE)isanewanalyticaltechnology'rapidly'developedinrecentyears.Withtheadvantagesofsmallsample.highsensitivity,highresolution.rapidanalysisandverycheaprunning,ithasbeenappliedinchemistry'.lifescienc...