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This study examined the antecedents of teachers' use of motivational strategies in the classroom using self-determination theory. It was found that teachers' autonomous causality orientation, perceived job pressure, and perception of student self-determined motivation influenced their need satisfaction. In turn, their need satisfaction had a positive direct impact on autonomous motivation. In addition, teachers' perception of their students' self-determined motivation directly predicted teachers' use of three motivational strategies in the classroom. Finally, their autonomous motivation positively predicted providing instrumental help and support and meaningful rationale, whereas controlled motivation negatively predicted providing instrumental help and support. [ABSTRACT FROM AUTHOR]

Reports on a study on the time-dependent behavior of quantum cellular automata (QCA) with imperfections. Variations of intercellular distances; Variations of intercell tunneling strengths; Effect of stray charges.

Examines the time-dependent behavioral pattern of quantum cellular automata (QCA) chains of quantum-dot cells. Consistency of each cell; Interactions of cells with nearby cells through Coulomb potentials; Proposal of QCA; Discussion of two different approaches concerning QCA.

Remote sensing of percentage residue cover (PRC) is required to manage crop residue and to provide a key parameter for several biogeochemistry models. However, the growth of the next crop, crop residue decomposition, and precipitation or irrigation can affect the spectral features of crop residue and decrease the spectral difference between crop residue and soil. These factors limit the time window of image acquisition for estimating PRC, especially for double cropping systems (two crops harvested in one year). Remote sensing sensors with a short revisit interval allow imagery to be captured for a specific period (e.g., soon after harvest) when these effects are minimal. SPOT imagery has a short revisit interval of two to three days because of its oblique viewing capacity, and provides balance between high resolution and wide-area coverage. The study aimed to investigate the potential of SPOT 5 imagery for predicting PRC in a typical area of China with a wheat (Triticum aestivum)-corn (Zea mays L.) double cropping system. A SPOT 5 image was acquired with three visible and near infrared bands and one shortwave infrared (SWIR) band, from which six normalized difference indices (NDI) were built. Wheat PRC values (n = 94) were measured immediately after wheat harvest using ground vertical photographs and divided into a calibration set (n = 62) and a validation set (n = 32). To estimate PRC, linear spectral analysis and three regression methods were used. Simple linear regression (SLR) was used for its simplicity, and stepwise regression (SR) and principal component regression (PCR) were used because they could exploit the spectral information from all available image bands. Besides, the bootstrap was used to assess the prediction uncertainty of the regression methods. The results demonstrated that the NDI41 index (derived from SWIR and green bands) performed the best among the four bands and the six indices for estimating PRC when using the SLR method, with a coefficient of determination (R²) of 0.588 and a root mean square error (RMSE) of 0.114 for the validation set. This estimation accuracy was similar to that observed for the SR and PCR models and much better than that for the linear spectral analysis (R² and RMSE were 0.326 and 0.208, respectively). However, NDI41 accompanied by SLR was the optimal choice for estimating PRC because of its simplicity. These results indicate that SPOT 5 imagery could be used to estimate PRC. Therefore, this study should contribute to crop residue management. [ABSTRACT FROM AUTHOR]

The purpose of this study was to identify student clusters with homogenous profiles in perceptions of task- and ego-involving, autonomy, and social relatedness supporting motivational climate in school physical education. Additionally, we investigated whether different motivational climate groups differed in their enjoyment in PE. Participants of the study were 2 594 girls and 1 803 boys, aged 14 -15 years. Students responded to questionnaires assessing their perception of motivational climate and enjoyment in physical education. Latent profile analyses produced a five-cluster solution labeled 1) ‘low autonomy, relatedness, task, and moderate ego climate’ group', 2) ‘low autonomy, relatedness, and high task and ego climate, 3) ‘moderate autonomy, relatedness, task and ego climate’ group 4) ‘high autonomy, relatedness, task, and moderate ego climate’ group, and 5) ‘high relatedness and task but moderate autonomy and ego climate’ group. Analyses of variance showed that students in clusters 4 and 5 perceived the highest level of enjoyment whereas students in cluster 1 experienced the lowest level of enjoyment. The results showed that the students' perceptions of various motivational climates created differential levels of enjoyment in PE classes. [ABSTRACT FROM AUTHOR]

The effect of piezoelectric polarization on GaN-based light emitting diodes (LEDs) with different kinds of prestrain layers between the multiple quantum wells (MQWs) and n-GaN layer is studied and demonstrated. Compared with the conventional LED, more than 10% enhancement in the output power of the LED with prestrain layer can be attributed to the reduction of polarization field within MQWs region. In this study, we reported a simple method to provide useful comparison of polarization fields within active region in GaN-based LEDs by using temperature-dependent electroluminescence (EL) measurement. The results pointed out that the polarization field of conventional LED was stronger than that of the others due to larger variation of the wavelength transition position (i.e., blue-shift change to red-shift) from 300 to 350 K, and thus the larger polarization field must be effectively screened by injecting more carriers into the MQWs region. [ABSTRACT FROM AUTHOR]

In this study, the effect of quantum barrier thickness in the multi-quantum wells active region on electrical and optical properties of nitride-based light emitting diodes (LEDs) were investigated and demonstrated. The forward voltage decreased as the thickness of quantum barrier decreased owing to the reduction of series resistance. The external quantum efficiency (EQE) and droop effect can be effectively improved by decreasing the barrier thickness which was attributed to the enhancement of the holes injection and uniform distribution in the active region. However, if barrier was too thin, it would get the opposite effect due to the influence of electron overflow. Regarding the hot/cold factor, the thinner quantum barrier of LEDs achieved a better performance. The reason is that the thicker quantum barrier with poor holes distribution resulted in the holes accumulation of a few MQWs near the p-side layer was more easily influenced by thermal effect and escaped from the QWs. [ABSTRACT FROM AUTHOR]

In this work, the InGaN/AlGaN multiple-quantum-well (MQW) near-ultraviolet (UV) light-emitting diodes (LEDs) with different aluminum compositions in the barrier layers are investigated and fabricated. The aluminum compositions of LED I, II, and III are 0, 2.5, and 3.85%, respectively. The light output powers of LED I, II, and III at an injection current of 350 mA are 95.46, 135.48 mW, and 179.54 mW, respectively. The light output power measured from LED III was 88% larger than that of LED I. The peak external quantum efficiency was enhanced from 9.24 to 17.26%. This result was attributed to the improvement of carrier confinement in the active region by using AlGaN-based barrier layers. The hot-cold effect of LEDs as functions of junction temperature currently is a very important key issue for actual application to LEDs. As the temperature increased, the injected carriers became excited and easily escaped from the active layer. Thus, the light output power of the LED decreased as the temperature increased. Compared with LED I and LED II, the light output power of LED III with better carrier confinement was decreased more slowly with increasing temperature. [ABSTRACT FROM AUTHOR]

Whether playing video games with prosocial content has an influence on empathy among players remains contentious in the research literature. Some evidence suggests playing cooperatively with other gamers enhances empathy, but data have not conclusively linked prosocial content with empathy. Further, mechanisms of this potential relationship are unclear, and little work has been conducted on how cognitive skills, such as fluid reasoning, may mediate this relationship. The current study examines these relationships with a large sample of 3034 youth (27.2% female, Mage = 11.2; range 8–17 at time 1) in Singapore. Data were considered longitudinally across two years in three waves. Ultimately, no evidence emerged that prosocial content in video games had any impact on empathy related outcomes, nor was fluid reasoning a mediator variable for any relationship. However, variables such as social competence and depression and anxiety symptoms were highly related to empathy measures. This evidence adds to the growing debate in the field that video games may not dramatically alter, whether positively or negatively, the development of emotional and behavioral outcomes for youth. [ABSTRACT FROM AUTHOR]

We present a realization of the sinusoidal transmission function using a series of zigzag-profiled strips where the transmission takes on the binary values 0 and 1 in a two-dimensional distribution. A zigzag transmission grating of 1000 line/mm has been fabricated and demonstrated on the soft x-ray beam of synchrotron radiation. The axial single-order diffraction indicates that the zigzag transmission grating is adequate for spectroscopic application. [ABSTRACT FROM AUTHOR]

Our students today face a knowledge-based economy, which requires the ability to learn independently, to be innovative in using and synthesizing knowledge, and to adapt fast to the changing world. Project Work (PW) is introduced as one of the instructional models for a more student-centered approach of learning in Singapore. The purpose of this study was to examine the impact of project work (PW) and study the motivational processes of PW using a self-determination theory (SDT) framework. A total of 435 students from Normal Academic stream (NA) and Normal Technical stream (NT) were recruited from four secondary schools in Singapore. Students? perceptions of the values of PW, basic psychological needs, relative autonomy, enjoyment, and grades were measured across three time points. Results showed that students valued the PW experience. However, their enjoyment, needs, and relative autonomy decreased significantly in the 10 to 12 weeks of PW experience. Multiple regression analyses revealed that post-PW enjoyment negatively predicted PW grades, while psychological needs, relative autonomy and pre-PW enjoyment positively predicted post-PW enjoyment. After 6-month PW, post-PW enjoyment emerged as a stronger predictor than grades in predicting the perceived skills learned from PW. The study applies selfdetermination theory to the PW context and highlights the importance of facilitating the three psychological needs in the PW context to enhance students? motivation and achievement in PW. [ABSTRACT FROM AUTHOR]

This study examined the relationships between the approach-avoidance dimension, as well as the mastery-performance dimension of achievement goals, implicit theory of intelligence, and behavioral regulations among engineering students in a polytechnic in the academic domain. Polytechnic students (n = 1359) from Singapore participated in the survey. They were assessed on achievement goal orientations, implicit beliefs, behavioral regulations, values, effort and enjoyment towards their course of study using questionnaires. Cluster analysis was conducted and the results showed that five distinct clusters could differentiate the students in terms of their achievement goals profiles. Follow-up tests between the clusters showed that the five clusters had differing psychological characteristics, and differing values, effort, and enjoyment towards their course of study. Taken together, the present study offers some insights into intraindividual's differences in achievement goals and its impact and offers some useful implications for interventions. [ABSTRACT FROM AUTHOR]

Abstract: Radiobiological models are used in modern radiotherapy to evaluate the biological effects of different treatment plans or modalities. A radiobiological model typically converts a physical quantity (e.g. absorbed dose) to a biological quantity (e.g. cell survival fraction). Currently, the linear-quadratic model (LQM) is the most widely used model. Since it is a deterministic model, the LQM naturally ignores the uncertainties arising from the stochastic randomness of energy depositions along radiation tracks and the inherent unpredictable nature of biological systems. Recently, many studies have revealed the detailed spatial and temporal distributions of DNA damages, e.g. the DNA double strand breaks (DSBs), along various types of radiation tracks traversing a cell nucleus. Studies have also been conducted to unravel the biological pathways that involve in how cells and tissues process DNA damages. As such, the author proposes to start developing a new multi-scale radiobiological model based on the “bottom-up” approach. The model includes a Monte Carlo procedure to treat the stochastic randomness of radiation-induced DNA damages, and it also includes the relevant intercellular and intracellular pathways to allow the DNA damages to evolve into higher-order biological endpoints, e.g. chromosome aberrations, cell death, or tumorigenesis. Because of its stochastic nature, the new model inherently addresses the uncertainty issue being ignored by LQM. More importantly perhaps is that the model opens a new way to study radiation effects that involve biological pathways, and therefore, may have a profound impact on radiotherapy in the future. [Copyright &y& Elsevier]

The authors report findings from a study into students' and teachers' perceptions of the effectiveness of group project work (PW) in promoting students' motivation and learning. The authors gathered students' views on whether PW satisfied their basic psychological needs, affected their motivation, and created opportunities for life skills development. In addition, the authors interviewed 13 of the teachers to assess the extent to which their perceptions matched those of their students. The findings showed that, in general, the students recognized the benefits of PW and perceived themselves as fairly motivated to do PW. However, some of the teachers felt that their students' lack of motivation and competence hindered their performance in PW. Nevertheless, when teachers and students were able to reconcile their differences and reciprocate each other's expectations, PW was carried out effectively, with students and teachers benefiting from the experience. [ABSTRACT FROM AUTHOR]

Kaposiform haemangioendothelioma is a rare soft-tissue tumour of infants and children, and presents as a moderately aggressive malignancy. We present the MRI findings of a histologically proven case of Kaposiform haemangioendothelioma without Kasabach-Merritt phenomenon or typical skin changes. Our case also reveals that the multiple foci of the cutaneous tumour have different MRI morphologies. These findings have not been reported in the literature to date. [ABSTRACT FROM AUTHOR]

Background. The project work (PW) initiative was launched in 2000 by the Ministry of Education, Singapore, to encourage application of knowledge across disciplines, and to develop thinking, communication, collaboration, and metacognitive skills. Although PW has been introduced for a few years, few studies have examined the motivation of students in PW, especially with the use of the recently proposed 2 × 2 achievement goal framework. Aim. To use a cluster analytic approach to identify students' achievement goal profiles at an intra-individual level, and to examine their links to various psychological characteristics and perceived outcomes in PW. Sample. Participants were 491 Secondary 2 students (meanage = 13:78, SD = 0:77) from two government coeducational schools. Method. Cluster analysis was performed to identify distinct subgroups of students with similar achievement goal profiles. One-way MANOVAs, followed by post hoc Tukey HSD tests for pairwise comparisons were used to determine whether there was any significant difference amongst clusters in terms of the psychological characteristics and perceived outcomes in PW. Results. Four distinct clusters of students were identified. The cluster with high achievement goals and the cluster with moderately high goals had the most positive psychological characteristics and perceived outcomes. In contrast, the cluster with very low scores for all four achievement goals had the most maladaptive profile. Conclusion. The study provides support for the 2 × 2 achievement goal framework, and demonstrates that multiple goals can operate simultaneously. However, it highlights the need for cross-cultural studies to look into the approach-avoidance dimension in the 2 × 2 achievement goal framework. [ABSTRACT FROM AUTHOR]

This study examined the network of relationships between sport ability beliefs, achievement goals, self-determination and female students' enjoyment in school physical education (PE). Female secondary students (n = 343) from a single-sex secondary school in Singapore participated in the survey. They were assessed on sport ability beliefs, goal orientations, relative autonomy, perceived competence and enjoyment in PE. The findings established that incremental belief predicted task orientation. In addition, relative autonomy, task orientation and perceived competence had strong and direct impact on enjoyment Overall, the present study offers some insightful thoughts for promoting enjoyment for girls in PE and physical activity. [ABSTRACT FROM AUTHOR]

Increased α-synuclein expression may be involved in the pathogenesis of Parkinson’s disease (PD). We investigated the association of Rep1 microsatellite and RsaI T-to-C substitution in the α-synuclein promoter region with the risk of PD by a case-control study. The RsaI C/C genotype and C allele were found less frequently in PD patients than in controls. A reduced risk of the Rep1- RsaI 0-C haplotype (OR = 0.57, 95% CI = 0.36–0.90) with PD was evident. The quantitative real-time PCR study showed that the α-synuclein mRNA expression was increased (although not significantly) in PD patients with RsaI T/T genotype or Rep1- RsaI 0-T haplotype as compared to T/C genotype or 0-C haplotype. Reporter constructs containing the RsaI C allele drove significantly lower transcriptional activity compared with the RsaI T allele in both IMR32 and 293 cells. The findings suggest that the RsaI T-to-C substitution may have a functional relevance to the susceptibility to PD. [ABSTRACT FROM AUTHOR]

This paper presents an experimental test of two contemporary motivation theories in the physical domain. The study combined experimentally-induced achievement goal involvement with autonomous and controlling communication styles based on self determination theory to examine young people's enjoyment, free-choice behavior and performance in relation to a golf task. Results showed that those in the autonomous condition, regardless of their goal involvement, reported greater enjoyment, persisted longer at the task and performed better than those in the controlling communication condition. Participants in the task involved condition performed better than those in the ego involved condition. Findings point to the need for further studies that test multiple theories in sport. The motivational impact of goal involvement may be better understood when considered concurrently with the autonomous or controlling nature of the context. Promoting autonomy and task involvement is likely to enhance positive affect and adaptive behaviors in sport among young people. [ABSTRACT FROM AUTHOR]

GaN metal-semiconductor-metal (MSM) ultraviolet photodetectors with titanium tungsten (TiW) transparent electrodes were fabricated and characterized. It was found that the 10-nm-thick TiW film deposited with a 300-W RF power can still provide a reasonably high transmittance of 75.1% at 300 nm, a low resistivity of 1.7 × 10-3 Ω·cm and an effective Schottky barrier height of 0.773 eV on u-CaN. We also achieved a peak responsivity of 0.192 A/W and a quantum efficiency of 66.4% from the GaN ultraviolet MSM photodetector with TiW electrodes. With a 3-V applied bias, it was found that minimum noise equivalent power and maximum D* of our detector were 1.987 × 10-10 W and 6.365 × 109 cmHz0.5W-1, respectively. [ABSTRACT FROM AUTHOR]

Background. Although several studies support the existence of a negative stream effect on lower-ability stream students' academic self-concept, there is not enough longitudinal research evidence to preclude the possibility that the stream effect may only be temporary. In addition, not much is known about the effect of streaming on changes in students' academic self-concept over time. Aims. The main aims of the study were to examine the effect of streaming on (a) the students' academic self-concept immediately after the streaming process, and at yearly intervals for 3 consecutive years, and (b) the changes in students' academic self-concept over a 3 year period. Sample. The sample comprised 495 Secondary 1 students (approximate age 13) from three government coeducational schools in Singapore. Method. A longitudinal survey using a self-reported questionnaire. Results. Results showed that the lower-ability stream students had a more negative academic self-concept than the higher-ability stream students immediately after streaming, but they had a more positive academic self-concept 3 years after being streamed. In addition, it was established that the students' academic self-concept declined from Secondary 1 to Secondary 3. Nonetheless, the decline was more pronounced for the higher-ability stream students than the lower-ability stream students. Conclusions. Streaming may have a short-term negative impact on lower-ability stream students' academic self-concept. However, in the long run, being in the lower-ability stream may not be detrimental to their academic self-concept. [ABSTRACT FROM AUTHOR]

There has been a plethora of studies in the past decade investigating task and ego achievement goal orientations in physical activity settings and how they might be associated with various cognitive, affective and behavioral variables. Although comprehensive narrative reviews of the field exist, no systematic review has been reported except one meta-analysis on only goals and affect. The present paper, therefore, reports a systematic review of 10 correlates of achievement goal orientations across 98 studies and 110 independent samples (total N = 21,076). Studies are invariably cross-sectional, leading to an inability to conclude causal effects, and are biased towards young people. Frequencies and effect size calculations show associations of varying magnitude between a task orientation and (a) beliefs that effort produces success (positive association: +); (b) motives of skill development and team membership (+); (c) beliefs that the purpose of sport/PE is for fostering mastery, fitness, and self-esteem (+); (d) perceptions of competence (+); (e) positive affect (+); (f) negative affect (negative association: -); (g) parental task orientation (+); and (h) various measures or markers of behavior (+). Associations of varying magnitude were found between an ego orientation and (a) beliefs that possessing ability produces success (+); (b) motives of status/recognition and competition (+); (c) beliefs that the purpose of sport/PE is for social status (+); (d) perceptions of competence (+); (e) unsportspersonlike attitudes, endorsement of intentionally aggressive sport acts, and the display of aggressive behaviors in sport (+); and (f) parental ego orientation (+). [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the vascularity in dysplastic nodules and well-differentiated and moderately to poorly differentiated hepatocellular carcinomas (HCCs) less than 2 cm using carbon-dioxide (CO2) US and angiography.Material and Methods: A total of 115 pathologically proven small liver tumors (0.7 approximately 2.0 cm) were included in the study. There were 31 dysplastic nodules, 49 well-differentiated HCCs and 35 moderately to poorly differentiated HCCs. A comparative study of angiography and CO2 US was carried out.Results: Of the dysplastic nodules, 28 out of 31 tumors were hypo- or isovascular at CO2 US. Twenty-seven out of 31 tumors were hypovascular at angiography. Of the well-differentiated HCCs, 38/49 showed hypervascularity at CO2 US while 24/49 tumors were hypervascular at angiography. All moderately to poorly differentiated HCCs showed hypervascularity at CO2 US, compared to 30/35 tumors at angiography.Conclusion: Most of the dysplastic nodules were hypovascular and most of the moderately to poorly differentiated HCCs were hypervascular. The vascularity of well-differentiated HCCs was in between the above tumors. Both CO2 US and angiography were equally effective in demonstrating the vascularities in dysplastic nodules and moderately to poorly differentiated HCCs. CO2 US was significantly superior to angiography when identifying the vascularity in well-differentiated HCCs. [ABSTRACT FROM AUTHOR]

The effect of strain relaxation in a relaxed InAs quantum dot (QD) capped with InGaAs is investigated by admittance and deep-level transient spectroscopy (DLTS). Strain relaxation markedly increases the emission time in the QD region and extends carrier depletion to the bottom GaAs layer. The experimental data show the presence of relaxation traps in the QD region and the neighboring bottom GaAs layer. The electron emission from the QD region is governed by a trap located at 0.17–0.21 eV below the QD ground state. The electron-escape process is identified as thermal activation at high temperatures and direct tunneling at low temperatures from the trap. In the bottom GaAs layer near the QD, DLTS reveals a relaxation trap at 0.37–0.41 eV relative to the GaAs conduction band. The energy difference between these two traps is comparable to the QD ground-state energy relative to the GaAs conduction-band edge, suggesting that the two traps may be the same trap which is pinned to the GaAs conduction band. The considerable difference between their properties may result from different atoms surrounding the trap. [ABSTRACT FROM AUTHOR]

Purpose: In this study, we investigated computationally and experimentally a hexagonal‐pattern array of spatially fractionated proton minibeams produced by proton pencil beam scanning (PBS) technique. Spatial fractionation of dose delivery with millimeter or submillimeter beam size has proven to be a promising approach to significantly increase the normal tissue tolerance. Our goals are to obtain an optimized minibeam design and to show that it is feasible to implement the optimized minibeams at the existing proton clinics. Methods: An optimized minibeam arrangement is one that would produce high peak‐to‐valley dose ratios (PVDRs) in normal tissues and a PVDR approaching unity at the Bragg peak. Using Monte Carlo (MC) code TOPAS we simulated proton pencil beams that mimic those available at the existing proton therapy facilities and obtained a hexagonal‐pattern array of minibeams by collimating the proton pencil beams through the 1–3 mm diameter pinholes of a collimator. We optimized the minibeam design by considering different combinations of parameters including collimator material and thickness (t), center‐to‐center (c‐t‐c) distance, and beam size. The optimized minibeam design was then evaluated for normal tissue sparing against the uniform pencil beam scanning (PBS) by calculating the therapeutic advantage (TA) in terms of cell survival fraction. Verification measurements using radiochromic films were performed at the Emory proton therapy center (EPTC). Results: Optimized hexagonal‐pattern minibeams having PVDRs of >10 at phantom surface and of >3 at depths up to 6 cm were achieved with 2 mm diameter modulated proton minibeams (with proton energies between 120 and 140 MeV) corresponding to a spread‐out‐Bragg‐peak (SOBP) over the depth of 10–14 cm. The results of the film measurements agree with the MC results within 10%. The TA of the 2 mm minibeams against the uniform PBS is >3 from phantom surface to the depth of 5 cm and then smoothly drops to ~1.5 as it approaches the proximal edge of the SOBP. For 2 mm minibeams and 6 mm c‐t‐c distance, we delivered 1.72 Gy at SOBP for 7.2 × 7.2 × 4 cm3 volume in 48 s. Conclusions: We conclude that it is feasible to implement the optimized hexagonal‐pattern 2 mm proton minibeam radiotherapy at the existing proton clinics, because desirable PVDRs and TAs are achievable and the treatment time is reasonable. [ABSTRACT FROM AUTHOR]

A new generation of medical grade 252Cf sources was developed in 2002 at the Oak Ridge National Laboratory. The combination of small size and large activity of 252Cf makes the new source suitable to be used with the conventional high-dose-rate remote afterload-ing system for interstitial brachy therapy. A recent in-water calibration experiment showed that the measured gamma dose rates near the new source are slightly greater than the neutron dose rates, contradicting the well established neutron-to-gamma dose ratio of approximately 2:1 at locations near a 252Cf brachytherapy source. Specifically, the MCNP-predicted gamma dose rate is a factor of two lower than the measured gamma dose rate at the distance of 1 cm, and the differences between the two results gradually diminish at distances farther away from the source. To resolve this discrepancy, we updated the source gamma spectrum by including in the ORIGEN-S data library the experimentally measured 252Cf prompt gamma spectrum as well as the true 252Cf spontaneous fission yield data to explicitly model delayed gamma emissions from fission products. We also investigated the bremsstrahlung X-rays produced by the beta particles emitted from fission product decays. The results show that the discrepancy of gamma dose rates is mainly caused by the omission of the bremsstrahlung X-rays in the MCNP runs. By including the bremsstrahlung X-rays, the MCNP results show that the gamma dose rates near a new 252Cf source agree well with the measured results and that the gamma dose rates are indeed greater than the neutron dose rates. [ABSTRACT FROM AUTHOR]

It has been claimed that young children in schools in Scotland cannot relate to the activities that are taught in the more traditional' PE curriculum, activities that predominately include team invasion games (TIG) such as basketball, soccer and hockey (Scottish Executive, 2004). However, one of the issues with this claim is that it does not appear to derive from any empirical, Scottish-based, research. The purpose of this study, therefore, was to investigate pupils' perceptions of and experiences in TIG within the PE curriculum in Scotland, specifically their perception of competence, enjoyment and the value they attach to games such as soccer and basketball. We gathered data from three year groups, primary 7 (P7) (age = 11 ± 0.8 yrs), secondary 2 (S2) (age 13.5 ± 0.5 yrs) and secondary 4 (S4) (age = 15 ± 0.4 yrs) from one urban state school in Edinburgh and its three feeder primary schools (n = 285). All of the pupils in this study completed a questionnaire and a sample from each year group took part in a focus group interview. We found that P7 pupils valued the role of TIG within their PE curriculum more highly than the 54 pupils. For all of the year groups in this study, there was a positive relationship between their perception of competence and enjoyment of TIG and the value they attached to them. These findings warrant further research into the ways in which TIG are delivered in Scottish schools to understand more fully why pupils in Scottish schools value the role of TIG less as they move from P7 to S4. [ABSTRACT FROM AUTHOR]

Regular physical activity is associated with numerous health benefits; yet, most adults do not engage in recommended amounts of physical activity. Understanding the personality of unmotivated individuals could assist in exercise program prescription. Hence, the purpose of this investigation was to determine whether personality differences existed among clusters of exercise motivated individuals. Participants (N = 609) completed a measure of goal orientations, perceptions of physical ability, personality, and self-reported engagement in moderate and strenuous exercise. Gender differences existed; thus, separate analyses were conducted. Results revealed 4 and 3 distinct motivated clusters for male and female participants, respectively. The lowest motivated cluster for men and women scored significantly lower on extraversion and conscientiousness as well as self-reported physical activity compared to the more motivated clusters. Future lines of intervention research are discussed based on the results. [ABSTRACT FROM AUTHOR]

This study tests the generalizability of the factor pattern, structural parameters, and latent mean structure of a multidimensional, hierarchical model of physical self-concept in adolescents across gender and grade. A children's version of the Physical Self-Perception profile (C-PSPP) was administered to seventh-, eighth- and ninth-grade high school students (N = 2,969). Two a priori models were proposed: a confirmatory factor-analytic model that hypothesized a multidimensional model of physical self-concept; and a structural equation model that proposed a multidimensional, hierarchical structure with global self-concept as a superordinate construct and physical self-concept as a domain- level construct that explained the covariances among the subdomains of the C-PSPR Both models satisfied multiple criteria for goodness-of-fit with the data in each individual gender and grade sample. Tests of the invariance of the factor pattern and structural parameters for both models across gender and grade were supported. Consistent with findings from other contexts, latent means analysis suggests that physical self-concept scores was higher in boys. [ABSTRACT FROM AUTHOR]

pp. 133–145 In recent years, people have bred freshwater pearls as a substitute for natural pearls that occur in seawater, and they have also developed water-soluble pearl powder (P-w) and ultra-micro (P-μ) and ultra-nano pearl powder (P-n) products. However, neither the scientific value of pearl powder, nor the differences in efficiencies of different pearl powder products is still unknown. In this study, the effectiveness of three kinds of pearl powder products in various applications was compared. Tests for transepidermal water loss (TEWL) and evaluations of the skin surface hydration of test subjects showed that pearl powder has a satisfactory moisturizing effect on skin and that P-μ has a distinctly stronger moisturizing effect than P-w. The three pearl powder products can also significantly reduce the activation of tyrosinase and free radicals. In tests for reducing power and 1,1-diphenyl-2-picrylhydrazyl (DPPH) for scavenging free radicals, P-n and P-μ showed better performance than P-w. These results provide a reliable scientific basis for the use of pearl powder in beauty treatment, resistance to aging, and clinical medical treatment. [ABSTRACT FROM AUTHOR]

This study was designed to investigate effects of xanthophylls on serum lipid profile (triglyceride, TG; cholesterol, CHO; high-density lipoprotein cholesterol, HDLC; and low-density lipoprotein cholesterol, LDLC) and nuclear factor (peroxisome proliferator-activated receptor gamma, PPARγ; PPAR gamma coactivator 1 alpha, PGC1α; retinoid X receptor gamma, RXRγ; and retinoic acid receptor alpha, RARα) gene expression of breeding hens and chicks. In experiment 1, 432 hens were divided into three groups and fed diets supplemented with 0 (as control group), 20 or 40 mg/kg xanthophylls. Blood was sampled at 7, 14, 21, 28 and 35 days of trial. Liver, duodenum, jejunum and ileum were sampled at 35 days of trial. Results showed that serum HDLC level of hens was increased after dietary 40 mg/kg xanthophyll addition for 21, 28 and 35 days, while serum TG, CHO and LDLC were not affected. Xanthophyll addition also increased PPARγ expression in jejunum, RXRγ expression in duodenum and jejunum, and RARα expression in liver and duodenum. Experiment 2 was a 2 × 2 factorial design. Male chicks hatched from 0 or 40 mg/kg xanthophyll diet of hens were fed diet containing either 0 or 40 mg/kg xanthophylls. Liver, duodenum, jejunum and ileum were sampled at 0, 7, 14 and 21 days after hatching. Blood samples were also collected at 21 days. Results showed that in ovo xanthophylls elevated PPARγ in duodenum and jejunum, and RXRγ and RARα in liver of chicks mainly within 1 week after hatching, while dietary xanthophylls increased serum HDLC level and PPARγ and RXRγ in liver from 2 weeks onwards. In conclusion, our research suggested xanthophylls can regulate serum lipid profile and nuclear factor expression in hens and chicks. [ABSTRACT FROM AUTHOR]

A novel global potential energy surface for H2S+(X 4A″) based on accurateab initiocalculations is presented. Energies are calculated at the multi-reference configuration interaction level with Davidson correction using aug-cc-pVQZ basis set plus core-polarisation high-exponent d functions. A grid of 4552 points is used for the least-square fitting procedure in the frame of a many-body expansion. The topographical features of the new potential energy surface are here discussed in detail. Such a surface is then employed for dynamic studies of the S(4S) + H2(X 1Σ+g) →SH+(X 3Σ−) + H(2S) reaction using the quasi-classical trajectory method. State specific trajectories are calculated, for both ground and ro-vibrationally excited initial states of H2(X 1Σ+g). Corrections to the zero point energy leakage of the classical calculations are also presented. Calculated reaction cross sections and rate constants are here reported and compared with available literature. [ABSTRACT FROM PUBLISHER]

The major objective of this research is to determine engineering GAC adsorber design criteria for removal of various organic contaminants found in the 3 drinking water sources in the Keum river basin. Dissolved Organic Carbon (DOC) and UV absorbance at 254 mm were chosen as parameters for overall organics level in raw and owed water. Removal of micropollutants including organophosphorus pesticides, MBAS, volatile organic chemicals (VOCs), phenol and NH3-N were also taken into consideration in bench and/or pilot studies, Treatment efficiencies for target contaminants in three different pilot plants with different raw water quality in the same Keum river basin were compared. Identification and decision of the treatment objectives were found to be important factors for determining design parameters such as GAC bed depth. Range of appropriate bed depth and reactivationfrequency for different treatment levels were suggested based on pilot studies. [ABSTRACT FROM AUTHOR]

This study investigated effects of xanthophylls (containing 40% lutein and 60% zeaxanthin) on gene expression of inflammatory mediators (cyclooxygenase-2 [COX-2] and induced nitric oxide synthase [iNOS]) and apoptosis (B cell lymphoma/leukemia-2 [Bcl-2] and caspase-3) of breeding hens and chicks. In Exp. 1, 432 hens were divided into 3 groups and fed diets supplemented with 0 (as the control group), 20, or 40 mg/kg xanthophylls. The liver, duodenum, jejunum, and ileum were sampled after 35 d. Results showed that 40 mg/kg of xanthophyll addition decreased COX-2 in the liver, iNOS in the liver and duodenum, and caspase-3 in the liver and jejunum while increasing Bcl-2 level in the liver and jejunum. Experiment 2 was a 2 x 2 factorial design. Male chicks hatched from hens fed 0 or 40 mg/kg xanthophyll diets were fed diets containing either 0 or 40 mg/kg xanthophylls. The liver, duodenum, jejunum, and ileum were sampled at 0, 7, 14, and 21 d after hatching. Results showed that in ovo xanthophylls reduced inflammatory mediators and apoptosis in the liver, duodenum, and jejunum of chicks mainly within 1 wk after hatching, whereas dietary xanthophylls only decreased iNOS expression in the liver from 2 wk onward. These results underlined important anti-inflammatory and antiapoptotic effects of maternal but not progeny dietary xanthophylls. In conclusion, xanthophylls can suppress inflammatory mediators and apoptosis in different tissues of hens and chicks. [ABSTRACT FROM AUTHOR]

Background: We conducted a retrospective analysis on 884 patients who were diagnosed with esophageal squamous cell carcinoma (ESCC) and treated with either the neutron brachytherapy in combination with external beam radiotherapy (NBT + EBRT) or 3-dimensional conformal radiation therapy (3D-CRT) to determine the differences in efficacy and morbidity between the two treatment groups.Methods: The 884 ESCC patients treated with either NBT + EBRT or 3D-CRT between 2002 and 2012 were retrospectively reviewed and analyzed. Multivariable Cox regression was used to compare oncologic outcomes of the two groups of patients in the context of other clinically relevant variables. The acute and chronic toxicities associated with the two groups were compared using Fisher exact and log-rank tests, respectively.Results: Among the 884 patients, 545 received NBT + EBRT and 339 received 3D-CRT (i.e. EBRT-only). The age range is 39-95 years (median 66). The follow-up time range is 3-145 months (median 32). The analysis shows that the NBT + EBRT group has higher overall survival rate and local control rate than that of the 3D-CRT group. The acute toxicity effects were acceptable for both groups of patients with the NBT + EBRT group showing higher rates of leukopenia and thrombocytopenia and the 3D-CRT group showing higher rates on fistula and massive bleeding.Conclusions: The patients treated with NBT + EBRT showed better oncologic outcomes than those treated with 3D-CRT. The toxicity effects were acceptable for both groups with the NBT + EBRT group showing higher rates on the acute effects and the 3D-CRT group showing higher rates on the late effects. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to retrospectively observe and analyze the long-term treatment outcomes for a total of 952 esophageal cancer patients who were treated with 252Cf neutron brachytherapy (NBT) in combination with external beam radiotherapy (EBRT). Methods and Materials: From November 2001 to March 2012, 952 patients with esophageal cancer underwent NBT in combination with EBRT. The patient numbers distributed over various cancer Stages I, IIA, IIB, III, and IVA were 9, 290, 51, 579, and 23, respectively. The total radiation dose to the reference point via NBT was 8-25 Gy-eq in three to five fractions with one fraction/week. The total dose via EBRT was 40-60 Gy delivered over a period of 5-6 weeks with normal fractionation. Results: The overall median survival time was 20.3 months. The 1-, 3-, and 5-year survival rates were 67.1%, 36.3%, and 26.6%, respectively. These results compare favorably with the results obtained from conventional high-dose rate in combination with EBRT. Although a majority of the patients (860 or 90.3%) developed Grades 1 and 2 esophagitis during treatment, the symptoms were effectively relieved after the application of antacid and surface anesthesia. Conclusions: The clinical data show that NBT in combination with EBRT produced favorable local control and long-term survival rates for patients with esophageal cancer and that the side effects are tolerable. As such, we conclude that this dual-modality method is an effective and safe way for treating esophageal cancer. [ABSTRACT FROM AUTHOR]

Purpose: The efficacy of a boron-containing cholesteryl ester compound (BCH) as a boron neutron capture therapy (BNCT) agent for the targeted irradiation of PC-3 human prostate cancer cells was examined. Materials and methods: Liposome-based delivery of BCH was quantified with inductively coupled plasma-mass spectrometry (ICP-MS) and high-performance liquid chromatography (HPLC). Cytotoxicity of the BCH-containing liposomes was evaluated with neutral red, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-suIfophenyl)-2H-tetrazolium (MTS), and lactate dehydrogenase assays. Colony formation assays were utilized to evaluate the decrease in cell survival due to high-linear energy transfer (LET) particles resulting from 10 B thermal neutron capture. Results: BCH delivery by means of encapsulation in a lipid bilayer resulted in a boron uptake of 35.2 ±4.3 µg/109 cells, with minimal cytotoxic effects. PC-3 cells treated with BCH and exposed to a 9.4x1011 n/cm² thermal neutron fluence yielded a 20-25% decrease in clonogenic capacity. The decreased survival is attributed to the generation of high-LET α particles and 7Li nuclei that deposit energy in densely ionizing radiation tracks. Conclusion: Liposome-based delivery of BCH is capable of introducing sufficient boron to PC-3 cells for BNCT. High-LET α particles and 7Li nuclei generated from 10B thermal neutron capture significantly decrease colony formation ability in the targeted PC-3 cells. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of longitudinal baffles on particles settling performance within a full-scale sedimentation basin with a flow rate of 1,000 m3/hr. Comparative experiments on turbidity removal efficiency and sludge deposit distribution were performed in longitudinally baffled and non-baffled sedimentation basins. The turbidity removal rate in the baffled sedimentation basin was observed to be higher than that in the non-baffled basin. In addition, the depth of the sludge deposit in the baffled sedimentation basin was approximately 20% less than that in the non-baffled sedimentation basin, and the sludge concentration was 10% higher. To explain these results and to further investigate the effects of longitudinal baffles, the authors performed computational fluid dynamics (CFD) simulation for both basin types. The results of this CFD simulation indicated that the flow, particularly near the outlet orifice, was more stable in the longitudinally baffled sedimentation basin. Moreover, it could be concluded that the longitudinal baffle enables a fully developed flow and is thus more effective for sedimentation. [ABSTRACT FROM AUTHOR]

We report on large ab initio calculation for the $4s^2$- 4s4p transitions in the Zinc-like sequence, using the multi-configuration Dirac-Hartree-Fock method. Results for fine-structure energy levels, the wavelengths, transition rates and lifetimes between Z = 70 (Yb) and Z= 92 (U) are presented and compared with other theories and experiments. The calculated values including core-valence correlation are found to be similar and to compare very well with other theories and experiments values. We believe that our extensive calculated values can guide experimentalists in identifying the fine-structure levels in their future work. [ABSTRACT FROM AUTHOR]

Abstract: We present a dynamical theory of nonlinear absorption and propagation of a laser pulse train that contains 20 subpulses with an individual pulse width of 100ps. It is shown that the accumulative nonlinearity and the reverse saturation absorption play important roles in the optical limiting performance and pulse shaping. When the incident field is not too strong, the population transfer reveals a slow response process, and the periodic sequence of short light pulses can be regarded as a continuous long pulse. The general theory is applied to fullerence , which is a popular reverse saturable absorption material and a good limiter because of its larger excited-state absorption cross-section compared with that of the ground state. The propagation of the front subpulses is mainly affected by the linear transition between the ground state and the first excited singlet state, while the latter subpulses are attenuated by the excited-state absorption. Moreover, these two different kinds of absorption mechanisms result in different radial distributions for different subpulses. The pulse propagation is studied by solving numerically the coupled rate equations and the propagation equation of the optical pulse intensity, using experimental parameters as input. We suggest a new method to measure the lifetime of the triplet state. [Copyright &y& Elsevier]

Objective:Obese patients with schizophrenia being treated with clozapine and non-psychiatric obese are often assumed to share the same physiological changes in obesity. The aim of this study was to identify possible metabolic and hormonal differences between non-psychiatric obese subjects (OB) and obese patients with schizophrenia being treated with clozapine (OSC).Subjects:Fifty-one normal healthy subjects (Nor, body mass index (BMI):23.2±0.3), 50 OB (BMI:31.7±0.7) and 71 OSC (BMI:30.4±0.5).Measurements:Anthropometric, metabolic and hormonal parameters were determined by anthropometry, enzyme autoanalyzer, immunoassay and enzyme-linked immunosorbent assay.Results:Triglyceride, total cholesterol divided by high-density lipoprotein (HDL) cholesterol (TC/HDL) and leptin levels were significantly higher whereas the HDL and the molar ratio of insulin-like growth factor-1 (IGF-1), and insulin-like growth factor binding protein (IGFBP)-3 levels were significantly lower in both OB and OSC groups than those in the Nor group. Compared to normal subjects, insulin and homeostasis model assessment (HOMA) index levels were significantly higher in OSC, and, in OSC, insulin sensitivity and insulin-like growth factor (IGF)-1 were significantly lower. Although the anthropometric parameters in the OB and OSC groups were similar, in the OSC group the waist-to-hip ratio (WHR), insulin levels and HOMA index were significantly higher, while insulin sensitivity, cholesterol, low-density lipoprotein (LDL) cholesterol, TC/HDL, LDL/HDL, IGF-1 and IGF-1/IGFBP-3 molar ratio were lower, than those of the OB group.Conclusion:Insulin homeostasis and lipid profiles in clozapine-treated schizophrenic obesity were different from those in non-psychiatric obesity with similar anthropometric parameters, body weight and BMI. Among the three groups, the highest fasting insulin, the lowest insulin sensitivity and the highest HOMA index occurred in the OSC group. The OSC group was characterized by impaired glucose–insulin homeostasis, abnormal lipid profiles and hormonal changes in the GH-IGF-IGFBP axis and in leptin.International Journal of Obesity (2008) 32, 436–442; doi:10.1038/sj.ijo.0803750; published online 23 October 2007 [ABSTRACT FROM AUTHOR]

We compared four different skin surface landmarks, the lower margin of the right 2nd costo-sternal junction (point A); the upper margin of the right 3rd costo-sternal junction (point B); the lower margin of the right 3rd costo-sternal junction (point C); and a point 5 cm below the manubrio-sternal junction (point D), in 20 cancer patients undergoing insertion of permanent central venous catheters whose tips were placed near the superior vena cava – right atrium (SVC-RA) junction under transoesophageal echocardiography guidance. The landmark was satisfactory if it was located within 1 cm of the SVC-RA junction. Points C and D were closer to the SVC-RA junction than points A and B (p < 0.0001). However, point C had the highest incidence (C: 70%, A: 0%, B: 20%, D: 30%, p < 0.0001) of being within 1 cm of the SVC-RA junction. [ABSTRACT FROM AUTHOR]

Dissolved air flotation (DAF) is a solid-liquid separation system that uses fine bubbles rising from the bottom to remove particles in water. In this study, we investigated the effect of L/W (L; length, W; width) on the hydrodynamic behavior in a DAF system using CFD (computational fluid dynamics) and ADV (acoustic Doppler velocimetry) technique. The factual full-scale DAF system, L/W ratio of 1:1, was selected and various L/W ratio conditions (2:1, 3:1, 4:1 and 5:1) were simulated with CFD. For modelling, 2-phase (gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using a Eulerian-Eulerian approach based on the assumption that a very small particle is applied in the DAF system. Also, for verification of CFD simulation results, we measured the actual velocity at some points in the full-scale DAF system with the ADV technique. Both the simulation and the measurement results were in good accordance with each other. We concluded that the L/W ratio and outlet geometry play an important role for flow pattern and fine bubble distribution in the flotation zone. In the ratio of 1:1, the dead zone is less than those in other cases. On the other hand, in the ratio of 5:1, the fine bubbles were more evenly distributed. [ABSTRACT FROM AUTHOR]

Fourteen microsatellite markers with a coverage of 63.5 cM on bovine chromosome 6 were selected, and 26 sire families with 2,260 daughters were analyzed for mapping quantitative trait loci (QTL) affecting 5 milk production traits in a Chinese Holstein population. In the analyses across 26 families and within the largest significant families with a one-QTL model fitted, a QTL near BMS470 was detected that affected fat yield at the 5% experiment-wide significance level. When a 2-QTL model was fitted in the across-family analysis, it was found that there might exist 2 QTL affecting the 3 yield traits, although the exact or empirical thresholds for the significance testing were unknown. In all analyses, the results for milk yield and protein yield were generally consistent, which might have resulted from the same genetic background for milk and protein yield. [ABSTRACT FROM AUTHOR]

This study tested the replicability and cross-cultural invariance of a trans-contextual model of motivation across 4 samples from diverse cultures. The model proposes a motivational sequence in which perceived autonomy support (PAS) in physical education (PE) predicts autonomous motivation, intentions, and behavior in a leisure-time (LT) physical activity context. High-school pupils from Britain, Greece, Poland, and Singapore completed measures of PAS and autonomous motives in a PE context. Good- fitting path-analytic models supported the main hypotheses of the trans-contextual model in the British, Greek, and Singaporean samples. PAS in PE had significant total effects on autonomous motives in LT, except in the Polish sample. The effect of autonomous motives in LT on physical activity intentions and behavior was mediated by theory of planned behavior constructs in all samples. Results supported the main hypotheses of the trans-contextual model across cultures, although the effect of PAS was not pervasive in the Polish sample. [ABSTRACT FROM AUTHOR]

A DAF (Dissolved-Air-Flotation) process has been designed considering raw water quality characteristics in Korea. Although direct filtration is usually operated, DAF is operated when freshwater algae blooms occur or raw water turbidity becomes high. Pre-sedimentation is operated in case when the raw water turbidity is very high due to rainstorms. A main feature of this plant is that the operation mode can be changed (controlled) based on the characteristics of the raw water to optimize the effluent quality and the operation costs. Treatment capacity (surface loading rate) and efficiency of DAF was found to be better than the conventional sedimentation process. Moreover, low-density particles (algae and alum flocs) are easily separated while the removal of them by sedimentation is more difficult. One of the main concerns for DAF operation is a high raw water turbidity. DAF is not adequate for raw water, which is more turbid than 100 NTU. In order to avoid this problem, pre-sedimentation basins are installed in the DAF plant to decrease the turbidity of the DAF inflow. For simulation of the actual operation, bench and full-scale tests were performed for highly turbid water conditions. Consequently, it is suggested that pre-sedimentation with optimum coagulation prior to DAF is the appropriate treatment scheme. [ABSTRACT FROM AUTHOR]

Purpose: To compare i.v. contrast-enhanced sonography (CEUS), power Doppler sonography (PDUS) and i.a. carbon dioxide-enhanced sonography (CO2US) in assessing hepatocellular carcinoma (HCC) vascularities before and after treatment. Differences between PDUS and CEUS with the aid of CO2US were also observed.Material and Methods: In all, 43 patients with 67 histologically proved HCCs were examined with PDUS, CEUS, and CO2US. Among these tumors, 36 were HCCs before treatment and 31 were HCCs treated by transcatheter arterial chemoembolization or percutaneous ethanol injection or a combination of these two treatments. CO2US was used as the gold standard when comparing the PDUS and CEUS.Results: Of the 36 untreated HCC tumors, 20 (55.6%) were hypervascular compared with the liver parenchyma at PDUS, 28 (77.8%) at CEUS, 31 (86.1%) at the early phase of CO2US and 32 (88.9%) at the late phase of CO2US. Of the 31 post-treatment HCCs, 11 (35.5%) showed hypervascularity at PDUS, 25 (80.6%) at CEUS, 25 (80.6%) at the early phase of CO2US and 26 (83.9%) at the late phase of CO2US.Conclusion: CO2US was superior to CEUS and CEUS was superior to PDUS for the detection of tumor vascularity in both untreated and treated HCCs. The duration of enhancement at CEUS was shorter than at CO2US. The ability of CO2US to detect additional small tumors was not possible with PDUS and CEUS. [ABSTRACT FROM AUTHOR]

Smooth motion generation is an important issue in the computer animation and virtual reality (VR) area. In general, the motion of a rigid body consists of translation and orientation. The former is described by a space curve in 3-dimensional Euclidean space, while the latter is represented by a curve in the unit quaternion space. Although there are well-known techniques for smoothing the translation curve in the Euclidean space, few results have been reported for smoothing motion as a whole. This paper improves the previous study and provides a more robust algorithm, which seeks to minimize the weighted sum of the strain-energy and the sum of the squared errors. [ABSTRACT FROM AUTHOR]

The rectifying direction of diblock co-oligomer molecular diodes is investigated theoretically by analyzing the asymmetric bias effects on the molecular orbitals. The results reveal two competitive mechanisms in determining the rectifying direction, asymmetric energy shift of eigenstates and asymmetric spatial localization of wave functions upon the reversal of bias voltage. It is demonstrated that the dominated mechanism may be converted between the two mechanisms by changing the molecular length, which induces an inversion of the rectification. This work indicates the relative orientation of the two moieties is not sufficient to decide the rectifying direction of co-oligomer diodes. [ABSTRACT FROM AUTHOR]