学习者学习的软件——“学件”

“学件”是用于学习者学习的软件。学件与课件不仅在概念上不同,更重要的是它们在服务对象、 使用目的、解决问题与制作要求的侧重点都有很大的不同。本文对学件的设计和制作提出了应该遵循的6个 原则,而对它的发展则预测性提出4个趋向。

Population Pharmacokinetics of Propofol Administered by TCI in Chinese Elderly Patients

Aim To investigate the population pharmacokinetics of propofol administered by TCI in Chinese elderly patients. Methods Thirty-two patients with ASA Ⅰ - Ⅱ , 65 - 82 years old, undergoing selective lower abdominal operation were studied. Propofol was administered by target-controlled infusion with Marsh parameter. The target plasma concentration was 3 μg＇ mL^-1. Radial arterial blood samples were collected and analyzed by reversed phase HPLC with fluorescence detection. Population pharmacokinetic modeling was performed using NONMEM. Inter-individual variability and intra-individual variability of propofol were estimated for clearances and volumes of distribution. The effects of age, body weight, lean body mass, gender, height, hemoglobin, total protein, albumin, creatinine, alanine aminotrans ferase （ALT）, and aspartate aminotransferase （AST） were investigated. The effects of coadministered opioid drugs were also studied. Results The pharmacokinetics of propofol in the Chinese elderly patients was best described by a three-compartment open model. Lean body mass was found to be a covariate for system clearance at significant level （ P 〈 0.005）. The clearance decreased linearly with age as well （ P 〈 0. 005）. The apparent volume of distribution for deep peripheral compartment （V3） was influenced by gender. Elderly female patients showed a higher value for V3. Conclusion The pharmacokinetics of propofol administered by TCI in Chinese elderly patients can be well described by a three-compartment open model. Inclusion of age, lean body mass and gender as covariates significantly improved the model. To ensure the accuracy and precision of target-controlled infusion, the population pharmacokinetic model applied to the individual patient should be adjusted reasonably.

Tree shrew models:A chronic social defeat model of depression and a one-trial captive conditioning model of learning and memory

Recent genome studies indicate that tree shrew is in the order or a closest sister of primates,and thus may be one of the best animals to model human diseases.In this paper,we report on a social defeat model of depression in tree shrew（Tupaia belangeri chinensis）.Two male tree shrews were housed in a pair-cage consisting of two independent cages separated by a wire mesh partition with a door connecting the two cages.After one week adaptation,the connecting door was opened and a brief fighting occurs between the two male tree shrews and this social conflict session consisted of 1 h direct conflict（fighting） and 23 h indirect influence（e.g.smell,visual cues） per day for 21 days.The defeated tree shrew was considered the subordinate.Compared with na？ve animals,subordinate tree shrews at the final week of social conflict session showed alterations in body weight,locomotion,avoidance behavior and urinary cortisol levels.Remarkably,these alterations persisted for over two weeks.We also report on a novel captive conditioning model of learning and memory in tree shrew.An automatic trapping cage was placed in a small closed room with a freely-moving tree shrew.For the first four trials,the tree shrew was not trapped when it entered the cage and ate the bait apple,but it was trapped and kept in the cage for 1 h on the fifth trial.Latency was defined as the time between release of the tree shrew and when it entered the captive cage.Latencies during the five trials indicated adaptation.A test trial 24 h later was used to measure whether the one-trial trapping during the fifth trial could form captive memory.Tree shrews showed much longer trapping latencies in the test trial than the adaptation trials.The N-methyl-d-aspartate（NMDA） receptor antagonist MK-801（0.2 mg/kg,i.p.）,known to prevent the formation of memory,did not affect latencies in the adaptation trails,but did block captive memory as it led to much shorter trapping latencies compared to saline treatment in the test trial.These results demonstrate a chronic social defeat model of depression and a novel one-trial captive conditioning model for learning and memory in tree shrews,which are important for mechanism studies of depression,learning,memory,and preclinical evaluation for new antidepressants.

Prediction of Secondary Structure and B Cell Epitope of GH Protein from Acipenser sinensis

[ Objective] The aim was to predict the secondary structure and B cell epitope of growth hormone （GH） protein from Acipenser sinensis. [Method] With the amino acid sequence of GH protein from A. sinensis as the base, the secondary structure of GH protein from A. sinensis was predicted by the method of Gamier-Robson, Chou-Fasman and Karpius-Schulz, and its cell epitope was predicted by the method of Kyte- Doolittle, Emini and Jameson-Wolf. [Result] The sections of 18 -23, 55 -55, 67 -73, 83 -86,112 -114,151 -157 and 209 -211 in the N terminal of GH protein molecule had softer structure and these sections could sway or fold to produce more complex tertiary structure. The sections of 19 -23, 51 -71,84 -95, 128 -139, 164 -176 and 189 -195 in the N terminal of GH protein could be the epitope of B cell and there were flexible regions in these sections or near these sections of GH protein molecule. So the dominant regions could be in these sections or near these sections. [ Conclusion] The research provided the basis for the preparation of monoctonal antibody of GH protein from A. sinensis and provided the reference for the discussion for the molecular regulation mechanism of A. sinensis.

On the Models of the Bilingual Education and Their Implementation Conditions

This paper carefully probes into the main models of the bilingual education in the world, deeply analyses the conditions and requirements on the implementation of the bilingual education in our schools, and clearly differentiates TEFL and TESL as well as bilingual education. The writer thinks that in China we teach English as a foreign language instead of a second language, that the bilingual education is the supreme level of the foreign language acquisition, and that the final goal of the bilingual education is to make learners simultaneously think and use Chinese and English in both ways as well as communicate with one another in two languages according to the situational context. Therefore, it is not easy to practice the bilingual education in a country like China, which is still poor in the English language context. But the situation will change as China enters WTO and the globalization speeds up.

VIBRATION IN HIGH-SPEED MILLING OF THIN-WALLED COMPONENTS

To investigate the vibration principle in machining thin-walled components, a dynamic model for end milling of flexible structures is built based on considering the variations in the dynamic chip thickness and the differences between up-milling and down-milling. Two milling experiments verify the model. Experimental results show that the model can predict the milling force and displacements simultaneously in the dynamic milling process.

Linearity of Removal in the Proeess of Optical Element Polishing

In the light of some assumptions that are very close to the practical working conditions,a very complicated polishing process of optical element can be simplified as a linear and shift invariant system that is relatd only to the speed,pres- sure and time of processing.In polishing,the removed material can be represented and entreated by the convolution of the removal function of polishing head and the dwell function.The properties of removal function are presented.The assumptions and methods given by the author have been shown to be correct and applicable by experiments using a ring lap to polish the optical surfac.

Construction of retroviral vector carrying HSV tk gene under control of human AFP enhancer core sequence and human pgk promotor *

AIM Tenstruct retroviral vector bringing HSV tk gene under control by human AFP enhancer core sequence and human pgk promotor.

Three 5’-flanking Regions of crtO Encoding β-carotene Oxygenase in Haematococcus pluvialis

Three separate 5＇-flanking regions （1.1 kb, 1.9 kb and 2.2 kb） of crtO were cloned through walking upstream. Results of sequence analysis show that three 5＇-flanking regions of crtO might have some similar putative cis-acting elements such as ABA （abscisic acid）-responsive element （ABRE）, C-repeat/dehydration responsive element （C-repeat/DRE）, light-responsive element （G-box, GAG-motif, I-box and ATC-motif）, wound-responsive element （WUN-motif）, auxin-responsive element （TGA-element）, MeJA-responsive element （TGACG-element） and MYB binding site （MBS）, except for typical TATA box or CCAAT box. These findings might mean diversiform regulatory patterns of crtO being in astaxanthin biosynthesis of Haematococcus pluvialis.

Poisson Theory of Generalized Birkhoff Systems

To study the Poisson theory of the generalized Birkhoff systems, the Lie algebra and the Poisson brackets were used to establish the Poisson theorem. The generalized Poisson condition for the first integral and the generalized Poisson theorem of the generalized Birkhoff systems are obtained. An example is given to illustrate the application of the result.

New type gate electrode of CNT-FED fabricated by chemical corrosive method

To obtain a triode structure canbon nanotube field emission display （CNT-FED）, the glass plate which contains a glass channels matrix is designed and used as the triode part of the CNT-FED. Normally, the gate electrode can be fabricated with screen printing methods and a channels matrix can be fabricated by two- faced chemical corrosion. By adjusting the etch time and the concentration of acid in the process, different shapes of the tunnels can be obtained. The size and morphology of channels are observed by a scanning electron microscope （SEM）, and the ingredients of the corrosion solution are detected by infrared ray （IR） analysis. Voltage is added to the triode structure for obtaining the brightness image of the spot on the screen. Eventually, the electron trace pulling from cathode to anode under an electric field is obtained by simulation. It is concluded that the simulation results accord with the experimental results which realize the optimized triode structure.

The Bipolar Theory of the Field-Effect Transistor:X.The Fundamental Physics and Theory(All Device Structures)

This paper describes the foundation underlying the device physics and theory of the semiconductor field effect transistor which is applicable to any devices with two carrier species in an electric field. The importance of the boundary conditions on the device current-voltage characteristics is discussed. An illustration is given of the transfer DCIV characteristics computed for two boundary conditions,one on electrical potential,giving much higher drift-limited parabolic current through the intrinsic transistor, and the other on the electrochemical potentials, giving much lower injection-over-thebarrier diffusion-limited current with ideal 60mV per decade exponential subthreshold roll-off, simulating electron and hole contacts. The two-MOS-gates on thin pure-body silicon field-effect transistor is used as examples

Effects of moulding sands and wall thickness on microstructure and mechanical properties of Sr-modified A356 aluminum casting alloy

The effects of different cooling conditions on the mechanical properties and microstructures of a Sr-modified A356 （Al-7Si-0.3Mg） aluminum casting alloy were comparatively investigated using three moulding sands including quartz, alumina and chromite into multi-step blocks. The results show that the mechanical properties and microstructures using chromite sand are the best. As the cooling speed increases, the dendrite arm spacing （DAS） decreases significantly and the mechanical properties are improved, and the elongation is more sensitive to the cooling speed as compared with the tensile strength. The increase of the properties is primarily attributed to the decrease of the DAS and the increase of the free strontium atoms in the matrix. In particular, the regression models for predicting both the tensile strength and the elongation for Sr-modified A356 aluminum casting alloy were established based on the experimental data.

Regulatory Analysis of IPP Isomerase Gene in Haematococcus pluvialis

The unicellular green alga Haematococcus pluvia/is uniquely accumulates carotenoids in the cytoplasm and in late developmental stages turns deep-red in color because of accumulation of astaxanthin in the cytosol. The enzyme, isopentenyl pyrophosphate （IPP） isomerase, plays a key role in astaxanthin biosynthesis of H. pluvialis. In this paper, two separate 5＇-flanking regions （1.8 kb and 2.5 kb） of IPP isomerase gene was cloned through walking upstream firstly. Results of sequence analysis =showed that two separate 5＇-flanking regions of IPP isomerase gene might have similar putative cis-acting elements such as ABA （abscisic acid）-responsive element （ABRE）, drought-responsive element （DRE/C-repeat）, light-responsive element （G-box, GAG-motif, I-box and ATC-motif）, heat-shock element （HSE）, wound-responsive element （WUN-motif）, SA （salicylic acid）-responsive element （TCA-element）, auxin-responsive element （TGA-element）, MeJA （methyl jasmonate）-responsive element （TGACG-element）, enhancer-like element involved in anoxic specific inducibility （GC-motif） and MYB binding sites （MBS and MRE）, except for typical TATA box or CCAAT box, which exhibit diversiform transcriptional patterns of IPP isomerase gene in astaxanthin biosynthesis of Haematococcus pluvialis.

Thermodynamics for chemical vapor synthesis of Nb nanopowder in NbCl_5-H_2-Ar system

Thermodynamics for chemical vapor synthesis （CVS） of Nb nanopowder in NbCl5-H2-Ar system was investigated by using FactSage software. The validation experiments were conducted to confirm the thermodynamics points. The results indicate that under the atmospheric pressure, the reduction approach from NbCl5（g） to Nb（s） is a stage-wise process with the formation of complex sub-chlorides, and is controllable at low hydrogen ratio （mole ratio of n（NbCl5）：n（H2）＆lt;1：180） and low temperature （＆lt;1050 ＆#176;C）. Furthermore, a reasonable amount of inert loading gas is favorable to increase the reduction ratio of NbCl5 and the powder yield. The as-synthesized Nb nanopowder with the homogeneous size of 30-50 nm and the powder yield of 85% （mass fraction） is obtained by the CVS process under n（NbCl5）：n（H2）：n（Ar）=1：120：1 and 950 ＆#176;C with the NbCl5 reduction rate of 96.1%.

Influence of gut microbiota on neuropsychiatric disorders

The last decade has witnessed a growing appreciation of the fundamental role played by an early assembly of a diverse and balanced gut microbiota and its subsequent maintenance for future health of the host. Gut microbiota is currently viewed as a key regulator of a fluent bidirectional dialogue between the gut and the brain(gut-brain axis). A number of preclinical studies have suggested that the microbiota and its genome(microbiome) may play a key role in neurodevelopmental and neurodegenerative disorders. Furthermore, alterations in the gut microbiota composition in humans have also been linked to a variety of neuropsychiatric conditions, including depression, autism and Parkinson's disease. However, it is not yet clear whether these changes in the microbiome are causally related to such diseases or are secondary effects thereof. In this respect, recent studies in animals have indicated that gut microbiota transplantation can transfer a behavioral phenotype, suggesting that the gut microbiota may be a modifiable factor modulating the development or pathogenesis of neuropsychiatric conditions. Further studies are warranted to establish whether or not the findings of preclinical animal experiments can be generalized to humans. Moreover, although different communication routes between the microbiota and brain have been identified, further studies must elucidate all the underlying mechanisms involved. Such research is expected to contribute to the design of strategies to modulate the gut microbiota and its functions with a view to improving mental health, and thus provide opportunities to improve the management of psychiatric diseases. Here, we review the evidence supporting a role of the gut microbiota in neuropsychiatric disorders and the state of the art regarding the mechanisms underlying its contribution to mental illness and health. We also consider the stages of life where the gut microbiota is more susceptible to the effects of environmental stressors, and the possible microbiota-targeted intervention strategies that could improve health status and prevent psychiatric disorders in the near future.

Experimental investigation of subsurface damage depth of lapped optics by fluorescent method

Subsurface defects were fluorescently tagged with nanoscale quantum dots and scanned layer by layer using confocal fluorescence microscopy to obtain images at various depths. Subsurface damage depths of fused silica optics were characterized quantitatively by changes in the fluorescence intensity of feature points. The fluorescence intensity vs scan depth revealed that the maximum fluorescence intensity decreases sharply when the scan depth exceeds a critical value. The subsurface damage depth could be determined by the actual embedded depth of the quantum dots. Taper polishing and magnetorheological finishing were performed under the same conditions to verify the effectiveness of the nondestructive fluorescence method. The results indicated that the quantum dots effectively tagged subsurface defects of fused-silica optics, and that the nondestructive detection method could effectively evaluate subsurface damage depths.

A Review of Colloid Transport in Fractured Rocks

Recent recognition of colloid and colloidassociated transport of strongly sorbing contaminants in fractured rocks highlights the importance of exploring the transport behavior of colloids under conditions prevailing in the field.The rapid transport of colloids through fractured rocks-as affected by the hydraulic properties of the flow system,the properties of fracture surface and the geochemical conditionshas not been sufficiently elucidated,and predictions of colloid transport through fractures have encountered difficulties,particularly at the field scale.This article reviews the current understanding of the mechanisms and modeling of colloid transport and retention in fractured rocks.Commonly used experimental techniques and approaches for conducting colloid transport experiments at different scales,ranging from the laboratory to the field scale,are summarized and commented upon.The importance of various interactions(e.g.,dissolution,colloid deposition,generation,mobilization and deposition of filling materials within fractures) between the flowing solution and the fracture walls(in many cases,with skin or coating on the host rock at the liquid-solid interface) has been stressed.Colloid transport through fractures of high heterogeneity has not yet been well understood and modeled at the field scale.Here,we summarize the current knowledge and understanding accumulated in the last two decades in regard to colloid and colloidassociated transport through fractures.Future research needs are also discussed.

A Fourteen-Year Climatology of the Southwest Vortex in Summer

Statistical studies were conducted on the southwest vortex(SWV) during the summers of 2000–13 using high-resolution reanalysis data with a horizontal resolution of 0.5°× 0.5°. A total of 578 SWVs were detected, with a maximum interannual frequency of 55. The variation of the interannual frequency featured a period of around six years. The most active period of SWVs was early July and the maximum occurrence of SWVs appeared in early morning(0200–0800 Beijing Standard Time(BST)). Most of the SWVs were short-lived, with only 66 cases(11.4%) lasting for more than 24 h. In addition, the moving tracks and three-dimensional shape of long-lived(≥ 36 h) SWVs are also presented. For those SWVs that lasted for more than 12 h, four types of SWVs(Types I–IV) were identified using a new method, and the results indicated that the dynamical and thermodynamical conditions before the formation of SWVs are effective indicators of the subsequent evolution of the vortex and associated severe weathers. Moreover, a further level of classification was also constructed for Type II SWVs, which accounted for the largest proportion out of Types I–IV, and the results indicated that the lifespan, radius and maximum 6-h precipitation were all closely related to the intensity of precipitation before the formation of SWVs.

High power collimated diode laser stack

A high power collimated diode laser stack is carried out based on fast-axis collimation and stack packaging techniques. The module includes ten typical continuous wave （cw） bars and the total output power can be up to 368W at 48.6A. Using a cylindrical lens as the collimation elements,we can make the fast-axis divergence and the slow-axis divergence are 0. 926 4° and 8. 206° respectively. The light emitting area is limited in a square area of 18.3 mm × 11 mm. The module has the advantage of high power density and offers a wide potential applications in pumping and material processing.