Is the use of no-till continuous or rotational? Quantifying tillage dynamics from timeordered spatially aggregated data

Understanding and documenting historical agricultural land use and farming practices is important for assessment of environmental benefits of no-till (NT). To address the need for quantitative estimates of time patterns of tillage practices, this study proposes modeling the time patterns using the Markov chains framework and estimating the probabilities of transition from one tillage-crop combination to another tillage-crop combination from time-ordered spatially aggregated data. We developed a first-order, four-state Markov chain model of tillage-crop dynamics in corn (Zea mays L.)–soybean (Glycine max L.) production systems and estimated the transition probabilities for the state of Iowa using the 1992 to 1997 data collected by the Conservation Technology Information Center. The transition probabilities strongly suggest that the majority of NT acreage is not in continuous but rather in rotational NT, i.e., NT crop production in rotation with conventional or other tillage systems. We find that the probability of two-year continuous NT is 8%, and that 70% of Iowa cropland has never used NT over two consecutive years. When three-year tillage history is considered on corn acreage, 3% is in continuous NT, 62% has never used NT, and the rest of the acreage is in rotational NT. When three-year tillage history is considered on soybean acreage, 4% is in continuous NT, 56% has never used NT, and the rest of the acreage is in rotational NT. The methodology presented is applicable to corn–soybean production systems in other regions and is generalizable to other cropping systems. Regional estimates of the use of rotational and continuous NT are likely to benefit simulation modeling for the assessment of the environmental effects of alternative tillage practices

Validation of the factor structure of the motivated strategies for learning questionnaire

In recent years, the motivated strategies for learning questionnaire (MSLQ) has been used to assess students’ motivational orientations and utilization of various learning strategies. Due to its significant effects on student outcomes such as academic performance and careers, research on the factor structure of motivated strategies for learning has received increasing attention. However, the existing literature indicates a dearth of studies focusing on the MSLQ dimensions in Vietnam. Therefore, this study aimed to ascertain the factor structure of the 31-item Student Motivation Scale (SMS), which is a subset of the larger 81-item MSLQ, in the context of Vietnam. The study utilized the Vietnamese version of the SMS to collect data from 317 high school students in Vietnam. The factorial analysis showed that the SMS has its original six-factor structure, which is made up of task value (TV), control beliefs, self-efficacy for learning and performance (SLP), test anxiety (TA), and intrinsic goal orientation (IGO). The present study recommended that school leaders and teachers should use the SMS to assess students’ motivation in the context of Vietnamese education

Formation energies of complexes of hydrogen and carbon atoms with vacancy in fcc aluminum from first-principles

The DFT calculations are performed to investigate the interactions of hydrogen and carbon atoms with vacancy in fee aluminum. The solution energies of hydrogen and carbon atoms in aluminum, the cohesive energies of these atoms with vacancy and the formation energies of impurity-vacancy complexes were calculatedyesБелгородский государственный университе

Effects of principals’ leadership styles on teachers’ commitment in Vietnam

In recent years, styles of transformational and transactional leadership have become an important area of research because of its significant impact on teachers’ outcomes such as commitment, job satisfaction, self-efficacy. However, the relationships between transformational and transactional leadership styles of school principals and teachers’ organizational commitment have been rarely investigated in the educational context in Vietnam. This study aimed to determine how transformational and transactional leadership styles influence the organizational commitment of Vietnamese high school teachers. The study employed two standardized surveys to collect data from 387 teachers at 24 public high schools in the Mekong Delta of Vietnam. The results of correlation coefficient analyses indicated that teachers’ organizational commitment was positively influenced by transformational leadership and negatively influenced by transactional leadership. In addition, the results of multiple regression analyses showed that the organizational commitment of teachers was predicted by all components of both leadership styles of principals. The present study suggested that school leaders might combine both transformational and transactional leadership styles in their leadership practices to improve teachers’ organizational commitment

Molecular weight assessment of proteins in total proteome profiles using 1D-PAGE and LC/MS/MS

BACKGROUND: The observed molecular weight of a protein on a 1D polyacrylamide gel can provide meaningful insight into its biological function. Differences between a protein's observed molecular weight and that predicted by its full length amino acid sequence can be the result of different types of post-translational events, such as alternative splicing (AS), endoproteolytic processing (EPP), and post-translational modifications (PTMs). The characterization of these events is one of the important goals of total proteome profiling (TPP). LC/MS/MS has emerged as one of the primary tools for TPP, but since this method identifies tryptic fragments of proteins, it has not generally been used for large-scale determination of the molecular weight of intact proteins in complex mixtures. RESULTS: We have developed a set of computational tools for extracting molecular weight information of intact proteins from total proteome profiles in a high throughput manner using 1D-PAGE and LC/MS/MS. We have applied this technology to the proteome profile of a human lymphoblastoid cell line under standard culture conditions. From a total of 1 × 10(7 )cells, we identified 821 proteins by at least two tryptic peptides. Additionally, these 821 proteins are well-localized on the 1D-SDS gel. 656 proteins (80%) occur in gel slices in which the observed molecular weight of the protein is consistent with its predicted full-length sequence. A total of 165 proteins (20%) are observed to have molecular weights that differ from their predicted full-length sequence. We explore these molecular-weight differences based on existing protein annotation. CONCLUSION: We demonstrate that the determination of intact protein molecular weight can be achieved in a high-throughput manner using 1D-PAGE and LC/MS/MS. The ability to determine the molecular weight of intact proteins represents a further step in our ability to characterize gene expression at the protein level. The identification of 165 proteins whose observed molecular weight differs from the molecular weight of the predicted full-length sequence provides another entry point into the high-throughput characterization of protein modification

The impact of the demographic transition on dengue in Thailand: Insights from a statistical analysis and mathematical modeling

Background: An increase in the average age of dengue hemorrhagic fever (DHF) cases has been reported in Thailand. The cause of this increase is not known. Possible explanations include a reduction in transmission due to declining mosquito populations, declining contact between human and mosquito, and changes in reporting. We propose that a demographic shift toward lower birth and death rates has reduced dengue transmission and lengthened the interval between large epidemics. Methods and Findings: Using data from each of the 72 provinces of Thailand, we looked for associations between force of infection (a measure of hazard, defined as the rate per capita at which susceptible individuals become infected) and demographic and climactic variables. We estimated the force of infection from the age distribution of cases from 1985 to 2005. We find that the force of infection has declined by 2% each year since a peak in the late 1970s and early 1980s. Contrary to recent findings suggesting that the incidence of DHF has increased in Thailand, we find a small but statistically significant decline in DHF incidence since 1985 in a majority of provinces. The strongest predictor of the change in force of infection and the mean force of infection is the median age of the population. Using mathematical simulations of dengue transmission we show that a reduced birth rate and a shift in the population's age structure can explain the shift in the age distribution of cases, reduction of the force of infection, and increase in the periodicity of multiannual oscillations of DHF incidence in the absence of other changes. Conclusions: Lower birth and death rates decrease the flow of susceptible individuals into the population and increase the longevity of immune individuals. The increase in the proportion of the population that is immune increases the likelihood that an infectious mosquito will feed on an immune individual, reducing the force of infection. Though the force of infection has decreased by half, we find that the critical vaccination fraction has not changed significantly, declining from an average of 85% to 80%. Clinical guidelines should consider the impact of continued increases in the age of dengue cases in Thailand. Countries in the region lagging behind Thailand in the demographic transition may experience the same increase as their population ages. The impact of demographic changes on the force of infection has been hypothesized for other diseases, but, to our knowledge, this is the first observation of this phenomenon

W-band Radio-over-fiber Link Based on Self-oscillating Optical Frequency Comb Generator

A 94.8 GHz radio-over-fiber link was implemented with a self-oscillating frequency comb. An LTE Advanced OFDM FDD 64-QAM signal of 20 MHz bandwidth was transmitted over 1.3 m wireless distance with an EVM of 2.23%