Clock generator and OOK modulator for RFID application

The clock generator and OOK modulator for RFID (Radio Frequency Identification) presented in this paper consist of a current source and delay elements. The simple constant-gm structure is adopted in the current source design and the current consumption of the current source is only about 2 μA. The delay elements, the clock generator and OOK modulator are introduced in detail in the paper. The designed circuits are fabricated by 0.6 μm CMOS process. The area of the core circuit is only about 400 μmμ0 μm. The delay time of all three samples is in the range of 9 μs to 21 μs when the supply voltage varies from 2 V to 4 V. As the measured results satisfy the system requirements, these circuit structures are suitable for RFID application.     

Science Letters： A robust polysilicon-assisted SCR in ESD protection application

A novel polysilicon-assisted silicon-controlled rectifier (SCR) is presented and analyzed in this paper, which is fabricated in HHNEC's 0.18 μm EEPROM process. The polysilicon-assisted SCRs take advantage of polysilicon layer to help bypass electro-static discharge (ESD) current without occupying extra layout area. TLP current-voltage (I-V) measurement results show that given the same layout areas, robustness performance of polysilicon-assisted SCRs can be improved to 3 times of con- ventional MLSCR's. Moreover, one-finger such polysilicon-assisted SCRs, which occupy only 947 μm2 layout area, can undergo 7-kV HBM ESD stress. Results further demonstrate that the S-type I-V characteristics of polysilicon-assisted SCRs are adjustable to different operating conditions by changing the device dimensions. Compared with traditional SCRs, this new SCR can bypass more ESD currents and consumes smaller IC area.     

A novel low-voltage high precision current reference based on subthreshold MOSFETs

INTRODUCTION With the development of modern electronics,there is a growing trend of designing a low-voltagehigh precision current reference in many mixed-signaland analog circuits such as data converters (Mehr andSinger, 2000; Oh et al., 2004), oscillators and PLLs(Razavi, 2001; Banba and Shiga, 1999). Low-costreasons need the reference to be realized in simplestandard CMOS logic process technology, withoutresorting to the use of BiCMOS process and specialdevices such as floating-g…     

Model of Current Threshold for Perception in Testing Electrical Safety Performance*

A generalized mathematical model of human body current threshold for perception was established and the current flowing through human body could be arbitrary cyclical waveforms.The relationship between human body current threshold for perception and current frequency, true root mean square(RMS) value and influence factor was described.A test system was established based on electroencephalogram(EEG) to study the relationship between human body current threshold for perception and current waveform, frequency ...     

Effects of different concentrations of antisense oligodeoxynucleotides (ASODN) on human pancreatic cancer cell line PaTu8988s

Objective: To study the effects of different concentrations of antisense oligodeoxynucleotides (ASODN) on human pancreatic cancer cell line PaTu8988s. Method: Human pancreatic cancer cell line PaTu8988s in exponential growth stage was used to study the effect of different drug concentrations on the cell line in the presence of different concentrations (0 μg/ml, 5 μg/ml, 25 μg/ml, 50 μg/ml, 10 μg/m, 200 μg/ml) of ASODN and sense oligodeoxynucleotides (SODN). Cell counts and 3-[4,5-dimethylthiazolzyl]-2,5-diphenyl tetrazolium bromide (MTT) assays were carried out. Results: The inhibitory rate on the cell line PaTu8988s was 98.73%, 95.76%, 69.49%, 33.05% and 0 for ASODM concentrations of 200 μg/ml, 100 μg/ml, 50 μg/ml, 25 μg/ml and 5 μg/ml at 48 hours. Conclusions: K-ras complementary ASODN can inhibit the growth of human pancreatic cancer cell line PaTu8988s by 30.05% to 98.73%. This is likely to contribute to the specificity of the K-ras mRNA complementary capped ASODN sequential codon. Non-specific effect and side effect of ASOND were observed for instance, the greater the concentration is, the earlier the peak of inhibitory rate is reached. In concentration, of 25 μg/ml to 100 μg/ml ASODN showed a dose-effect correlation.     

Development of an indirect competitive ELISA for simultaneous detection of enrofloxacin and ciprofloxacin

Modified 1-ethyl-3-(3-dimethylaminopropy) carbodiimide (EDC) method was employed to synthesize the artificial antigen of enrofloxacin (ENR), and New Zealand rabbits were used to produce anti-ENR polyclonal antibody (pAb). Based on the checkerboard titration, an indirect competitive enzyme-linked immunosorbent assay (ELISA) standard curve was established. This assay was sensitive and had a linear range from 0.6 to 148.0 μg/kg (R ²=0.9567), with the half maximal inhibitory concentration (IC₅₀) and limit of detection (LOD) values of 9.4 μg/kg and 0.2 μg/kg, respectively. Of all the competitive analogues, the produced pAb exhibited a high cross-reactivity to ciprofloxacin (CIP) (87%), the main metabolite of ENR in tissues. After optimization, the matrix effects can be ignored using a 10-fold dilution in beef and 20-fold dilution in pork. The overall recoveries and coefficients of variation (CVs) were in the ranges of 86%–109% and 6.8%–13.1%, respectively. It can be concluded that the established ELISA method is suitable for simultaneous detection of ENR and CIP in animal tissues.     

Anti-allergic effects of ethanol extracts from brown seaweeds

Ethanol extracts of brown seaweeds from Pakistan and China were isolated and compared for their antiallergenic activities.They included Sargassum tennerimum (ST) and Sargassum cervicorne (SC) from Pakistan,and Sargassum graminifolium turn (SG),Sargassum thunbergii (STH),and Laminariajaponica (LJ) from China.The ethanol extracts of these brown seaweeds were optimized at 85% (v/v) ethanol for the maximum yield of phlorotannin,an inhibitor against hyaluronidase.Total phlorotannins contained in the crude extracts were measured as 1.71% (SG),0.74% (STH),0.97% (LJ),3.30% (SC),and 5.06% (ST).The 50% inhibitory concentrations (IC50) of Pakistani SC and ST were 109.5 and 21 μg/ml,respectively,lower than those of Chinese SG,STH,and LJ (134,269,and 148 μg/ml,respectively).An antiallergic drug,disodium cromoglycate (DSCG),had an IC50=39 μg/ml,and a natural inhibitor of hyaluronidase,catechin,had an IC50=20 μg/ml.The IC50 of ST extract was found similar to that of catechin (21 vs 20 μg/ml) and lower than that of DSCG (21 vs 39 μg/ml).This suggests that ST is a potent inhibitor of hyaluronidase,indicating a promising future development of natural antiallergic medicines or functional foods.     

Mechanism of action of two insect toxins huwentoxin-III and hainantoxin-VI on voltage-gated sodium channels

Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China. Their venoms contain abundant peptide toxins. Two new neurotoxic peptides, huwentoxin-III (HWTX-III) and hainantoxin-VI (HNTX-VI), were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography (RP-HPLC). The mechanism of action of HWTX-III and HNTX-VI on insect neuronal voltage-gated sodium channels (VGSCs) was studied via whole-cell patch clamp techniques. In a fashion similar to δ-atracotoxins, HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na⁺ current in cockroach dorsal unpaired median (DUM) neurons. Meanwhile, 10 μmol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel. HWTX-III inhibited VGSCs on DUM neurons (concentration of toxin at half-maximal inhibition (IC₅₀)≈1.106 μmol/L) in a way much similar to tetrodotoxin (TTX). HWTX-III had no effect on the kinetics of activation and inactivation. The shift in the steady-state inactivation curve was distinct from other depressant spider toxins. The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides.     

Non-occupational lead exposure and hypertension in Pakistani adults

INTRODUCTION Blood-Pb levels are taken as representative of dose/exposure, as all clinical symptoms resulting from the toxic effects of Pb are manifested mainly in blood. Lead exposure of children correlates with de- creased IQ, symptoms of hyper kinesis or minima brain dysfunction, poor learning, or defects in specific neuromotor tasks (Landgrin et al., 1980). Large number of observations over the years has associated lead exposure with human diseases (McMichael and Johnson, 1982). Ca…     

Students’ communicative behavior adaptability in CSCL environments

By the proliferation of online courses, the social dimension of computer supported collaborative learning (CSCL) is becoming more important than before. Research shows that communicative behavior adaptation to the computer medium is a critical issue in CSCL social relationship development. Two dominant theories in the CSCL field, social information processing theory and adaptive structuration theory, argue that individuals do not simply receive the technology passively but they adapt their behavior to increase benefits from the technology. This paper develops an instrument in order to operationalize the notion of individual’s communicative behavior adaptability in CSCL. Through an exploratory factor analysis performed on a small sample of post graduate students of an online degree in an Australian university, three factors have been unveiled: (1) individual perception of self-representation, (2) individual perception of compatibility, and (3) individual perception of the use of computer technology. Identification of these factors is expected to facilitate understanding of individuals’ social behaviors in CSCL environment, which in turn will guide the design of CSCL systems. In addition, the paper examines the relationships between the extracted factors and four environmental factors: learner’s characteristics, course characteristics, instructor characteristics, and technology characteristics. The results show that none of these characteristics strongly affect perception of self-representation or perception of the use of computer technology. On the other hand, a strong relationship was found between perception of compatibility and learner’s and course characteristics. The reliability as well as validity of the study is examined and findings are discussed. These findings will provide further insights into the design process of CSCL systems.     

Confidence and gender differences on the Mental Rotations Test

The present study examined the relation between self-reported confidence ratings, performance on the Mental Rotations Test (MRT), and guessing behavior on the MRT. Eighty undergraduate students (40 males, 40 females) completed the MRT while rating their confidence in the accuracy of their answers for each item. As expected, gender differences in favor of men were obtained. Results also indicated a positive correlation between confidence ratings and scores on the MRT, as well as negative correlations between confidence ratings and MRT outcomes presumed to reflect propensity to guess. More elaborate analyses using a measure of accuracy of predictions (the Brier score) indicated that men have a more accurate perception of their performance on the MRT than women do. Findings are discussed in terms of their implications for the interpretation of gender differences and guessing behavior on the MRT.     

A study of the relationship between expression level of TRF1 protein and telomerase activity in human acute leukemia

INTRODUCTION Telomeres are distinctive DNA-protein struc-tures that cap the ends of linear chromosomes.It is very important to keep the chromosomes stabilization.Telomerase activity is closely linked to attainment of cellular immortality,a step in carcinogenesis,while lack of such activity contributes to cellular senes-cence.Telomerase is activated in more than85%ofmalignant tumors(Hiayma et al.,1997).Human te-lomeric repeat binding factor1(TRF1)is a telomere associated with proteins a…     

Development and evaluation of immunoassay for zeranol in bovine urine

A high affinity polyclonal antibody-based enzyme linked immunosorbent assay （ELISA） was developed for the quantification of zeranol in bovine urine. On the basis of urine matrix studies, the optimized dilution factors producing insignificant matrix interference were selected as 1：5 in pretreatment. In the improved ELISA, the linear response range was between 0.02 and 1 μg/ml, and the detection limit was 0.02 μg/ml for the assay. The overall recoveries and the coefficients of variation （CVs） were in the range of 82%-127% and 3.5%-8.8%, respectively. Thirty-six bovine urine samples spiked with zeranol （ranging from 0.2 to 10 μg/ml） were detected by the ELISA and liquid chromatography （LC） method, and good correlations were obtained between the two methods （R^2=0.9643）. We conclude that this improved ELISA is suitable tool for a mass zeranol screening and can be an altemative for the conventional LC method for zeranol in bovine urine.     

Native and nonnative rater behavior in grading Korean students’ English essays

The purpose of the study is to investigate rating behavior between Korean and native English speaking (NES) raters. Five Korean English teachers and five NES teachers graded 420 essays written by Korean college freshmen and completed survey questionnaires. The grading data were analyzed with FACETS program. The results revealed Korean raters’ inferiority in measuring linguistic components. Furthermore, the Korean raters were more severe in scoring grammar, sentence structure, and organization, whereas the NES raters were stricter toward content and overall scores. In addition, the analysis of the raters’ responses on survey discovered that the NNS raters’ perception spread into content and grammar as the most difficult feature to grade, while all NES raters thought content as the most difficult. Based on these research findings, future research suggestions and implications are discussed.     

A comparative study of mothers’ beliefs and childrearing behaviour: The effect of the child’s disability and the mother’s educational level

The article presents the results of a data analysis intended to examine the relationship between children’s personality, maternal beliefs and childrearing behaviour and various disabilities on the one hand (mildly, moderate or severe mental handicap, sensorial handicap, developmental disabilities) and mothers’ educational level on the other. Data were taken from 102 mothers of disabled children between the ages of three and six. The children came from the Walloon Region of Belgium and were regularly counselled by an early intervention team (Services d’Aide Précoce — SAP). Variance analyses were performed on questionnaire data from the total sample (n=102). The questionnaires were based on the Five Factor Model of personality rating (Roskam, de Maere-Gaudissart, & Vandenplas-Holper, 2000), and on Sameroff’s levels of parental development for the rating of maternal beliefs. Factorial correspondence analyses were also performed on maternal self-reported childrearing behaviour as described in 50 interviews with mothers, analysed with a coding gird.     

Relationship between social perception and peer status in children with learning disabilities

This study was undertaken to examine the social perceptual skill deficit theory in explaining the low peer acceptance of children with learning disabilities. The quality of tests measuring social perception was also examined. Thirty 9- to 12-year-old children with learning disabilities and a matched control group were given two measures of social perception: a laboratory task and a behavior rating scale. The behavior rating scale was completed by the children's teachers. In addition, the Peer Acceptance Scale (Bruininks, Rynders, & Gross, 1974) was administered to assess peer status. Results showed that the children with learning disabilities differed significantly from their nondisabled peers on each of the three measures-the children with learning disabilities obtained lower social perception and peer acceptance scores. However, the relationships between sociometric status and social perception varied as a function of task. A small but significant correlation wa found between the behavior rating scale and peer status. The laboratory task was not correlated with either the behavior rating scale or peer status. Results are discussed in terms of the psychometric properties of laboratory versus naturalistic measures of social perception and the importance of establishing the external validity of social skill measures by correlating them with outcome measures such as peer status.     

Emotion, Confidence, Perception and Expectation Case of Mathematics

Students’ concerns about mathematics can significantly affect their ability to learn the subject. In particular, their anxieties and attitudes can greatly affect how they perceive their own mathematical competence, and in return, this may make them reluctant to pursue mathematical studies. Many researchers believe in the role of active learning environments in reshaping students’ perception of and emotions about mathematics. This paper reports the results of an investigation on the effect of one such environment. As a result of being exposed to an active learning environment, a group of 21 cohort students showed opinion changes from a pre- to post-survey statements significantly on emotion and noticeably on confidence and perception statements. There was, however, no statistically significant change observed on the opinions of a group of 41 traditional students.     

MEASURING THE CONFIDENCE OF 8TH GRADE TAIWANESE STUDENTS’ KNOWLEDGE OF ACIDS AND BASES

The present study investigated whether gender differences were present on the confidence judgments made by 8th grade Taiwanese students on the accuracy of their responses to acid–base test items. A total of 147 (76 male, 71 female) students provided item-specific confidence judgments during a test of their knowledge of acids and bases. Using the correctness of the answer responses, a confidence rating score, an unweighted rating score, and a relative confidence rating score were calculated for each respondent. The correlations between the boys and girls for each score area showed girls as scoring higher than boys in their knowledge of acids and bases, were more confident in this knowledge, and more willing to express different levels of confidence among the test items.     

流动儿童城市适应状况及过程:一项质性研究的结果

This article employs qualitative research methods to explore the urban adaptation and adaptation processes of Chinese migrant children. Through twenty-one in-depth interviews with migrant children, the researchers discovered: The participant migrant children showed a fairly high level of adaptation to the city; their process of urban adaptation emerged as three categories: the U-Type, the J-type, and the “flat line” type. Also explored were long-term acquisition of explicit behaviors, implicit notions, adaptation to the socio-cultural environment, and success in education as difficult aspects of adaptation. After comparing these three processes, the research team developed a theory of migrant children urban adaptation. It hypothesizes that during the urban adaptation process, migrant children will encounter four stages of development: excitement and curiosity, shock and resistance, exploration and adaptation, and finally integration and assimilation. __________ Translated by Amanda Weiss from Beijing Shifan Daxue Xuebao (Shehui Kexue Ban) 北京师范大学学报 (社会科学版) (Journal of Beijing Normal University (Social Sciences)), 2008, (3): 9–20, revised by Deane Neubauer, Emeritus Professor, University of Hawaii