Universality in odd-even harmonic generation and application in terahertz waveform sampling

Odd-even harmonics emitted from a laser-target system imprint rich, subtle information characterizing the system's dynamical asymmetry, which is desirable to decipher. In this Letter, we discover a simple universal relation between the odd-even harmonics and the asymmetry of the THz-assisted laser-atomic system -- atoms in a fundamental mid-IR laser pulse combined with a THz laser. First, we demonstrate numerically and then analytically formulize the harmonic even-to-odd ratio as a function of the THz electric field, the source of the system's asymmetry. Notably, we suggest a scaling that makes the obtained rule universal, independent of the parameters of both the fundamental pulse and atomic target. This universality facilitates us to propose a general pump-probe scheme for THz waveform sampling from the even-to-odd ratio, measurable within a conventional compact setup

Undergraduate Medical Education Reform in Viet Nam for a Primary Health Care Workforce

Strong primary health care (PHC) systems require a robust PHC workforce. Traditionally, medical education takes place in academic medical centres that favour subspecialty care rather than PHC settings. This may undervalue primary care as a career and contribute to a shortage of PHC workers. However, designing undergraduate medical education curricula that incorporate early experiences in clinical care delivery at PHC sites remains a challenge, including in many low- and middle-income countries (LMICs). This paper describes how a collaboration between Harvard Medical School and five medical schools in Vietnam, and in-country collaborations among the Vietnamese medical schools, facilitated curricular innovation and co-creation of coursework relevant to PHC through the development of a Practice of Medicine (POM) course. The collaboration implemented a technical assistance strategy consisting of in-person workshops, focused virtual consultations, on-site ‘office hours’, site visits and observations to each of the five medical universities, and immersion trips to support the creation and implementation of the POM course. A pilot program was started at a single site and then scaled nationally using local customisation, experience, and expertise utilising a train-the-trainers approach. As a result, five new POM courses have been developed by five Vietnamese institutions. Fifty Vietnamese faculty received training to lead the POM course development, and 228 community-based preceptors have been trained to teach students at PHC sites. A total of 52 new PHC and community-based clinical training sites have been added, and 3,615 students have completed or are currently going through a POM course. This experience can serve as a model for future academic collaborations to support the development of a robust PHC workforce for the 21st century

Delays in the diagnosis and treatment of tuberculosis patients in Vietnam: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Treatment delay is an important indicator of access to tuberculosis diagnosis and treatment. Analyses of patient delay (i.e. time interval between onset of symptoms and first consultation of a health care provider) and health care delay (i.e. time interval between first consultation and start of treatment) can inform policies to improve access. This study assesses the patient, health care provider and total delay in diagnosis and treatment of new smear-positive pulmonary tuberculosis patients, and the risk factors for long delay, in Vietnam.</p> <p>Methods</p> <p>A cross-sectional survey of new patients treated by the National Tuberculosis Control Programme was conducted in 70 randomly selected districts in Vietnam. All consecutively registered patients in one quarter of 2002 were interviewed using a pre-coded structured questionnaire.</p> <p>Results</p> <p>Median (range) delay was 4 weeks (1–48) for total, 3 (1–48) weeks for patient and 1 (0–25) week for health care delay. Patients with long total delay (≥ 12 weeks, 15%) accounted for 49% of the cumulative number of delay-weeks. Independent risk factors (p < 0.05) for long total delay were female sex, middle age, remote setting, residence in the northern or central area, and initial visit to the private sector. For long patient delay (≥ 6 weeks) this was female sex, belonging to an ethnic minority, and living at > 5 km distance from a health facility or in the northern area. For long health care delay (≥ 6 weeks) this was urban setting, residence in the central area and initial visit to a communal health post, TB hospital or the private sector.</p> <p>Conclusion</p> <p>Analyses of patient and treatment delays can indicate target groups and areas for health education and strengthening of the referral system, in particular between the private sector and the NTP.</p

Molecular epidemiology of Japanese encephalitis in northern Vietnam, 1964?2011: genotype replacement

Background: Japanese encephalitis virus (JEV) is an arthropod-borne virus causing serious public health issues in Asia. JEV consists of five genotypes and recent studies have shown the emergence of JEV genotype I (GI) and its replacement of genotype III (GIII). Using an archival JEV collection, we investigated the molecular evolution of JEV in Vietnam over the last 48 years (1964-2012) in humans, mosquitoes, and pigs, within the global context. Methods: The nine JEV isolates from humans, pigs, and mosquitoes sequenced in this study and 29 sequences available in GenBank were used to analyze the envelope (E) protein of the Vietnamese JEVs. A collection of 225 cerebrospinal fluid specimens from patients with suspected Japanese encephalitis (JE) was also tested and genotyped with real-time RT-PCR. Results: The 38 E genes identified with sequencing and nine Vietnamese JEV strains genotyped with real-time RT-PCR, belonging to two lineages, evolved in accordance with those in the rest of the world. The first GIII strain was detected in humans in Vietnam in 1964, and in mosquitoes in 1979, whereas GI strains were first detected in humans and mosquitoes in 1990 and 1994, respectively. After 2004, GI was the only genotype detected in Vietnam, demonstrating that the GIIII strains had been displaced by GI strains. Five haplotypes were identified in the Vietnamese JEVs, with SKSS predominant. The S123N and S123R substitutions in the E protein were already present in the Vietnamese JEVs. Conclusion: This study describes the long evolutionary history of JEV in Vietnam over 34 years, which correlates well with the global evolution of JEV. The Vietnamese GIII strains have been replaced by GI strains in mosquitoes, pigs, and humans. The predominant haplotypes of the Vietnamese strains support this genotype displacement in Vietnam. Further surveillance is required to confirm the disappearance of the GIII strains in nature and the emergence of new pathogens causing encephalitis in Vietnam, after the long-term use of JEV vaccines in that country

Using Market Variables in Financial Distress Prediction for Vietnamese Listed Companies

This paper aims to investigate the classification power of market variables as predictors in the financial distress prediction model for listed companies in a frontier market as Vietnam securities market. Data is collected from 70 financially distressed companies that suffer a loss in 3 consecutive years and 156 non-financially distressed companies in Vietnam from 2010 to 2017. Four different models have been constructed using Logit regression and SVM analysis technique to make a prediction in 1 to 3-year ahead. The analysis results show that combining accounting ratios with market variables such as price volatility and P/E can improve the classification ability of the ex-ante model. In addition, contrary to the results of related previous researches in emerging markets, in this study, Logit models outperform SVM models. Therefore, for future research, models that apply other machine learning classifiers such as Decision Tree (DT) or Neural Network (NN) should be investigated

Distal Hydrophobic Loop Modulates the Copper Active Site and Reaction of AA13 Polysaccharide Monooxygenases

Polysaccharide monooxygenases (PMOs) use a type-2 copper center to activate O2 for the selective hydroxylation of one of the two C–H bonds of glycosidic linkages. Our electron paramagnetic resonance (EPR) analysis and molecular dynamics (MD) simulations suggest the unprecedented dynamic roles of the loop containing the residue G89 (G89 loop) on the active site structure and reaction cycle of starch-active PMOs (AA13 PMOs). In the Cu(II) state, the G89 loop could switch between an “open” and “closed” conformation, which is associated with the binding and dissociation of an aqueous ligand in the distal site, respectively. The conformation of the G89 loop influences the positioning of the copper center on the preferred substrate of AA13 PMOs. The dissociation of the distal ligand results in the bending of the T-shaped core of the Cu(II) active site, which could help facilitate its reduction to the active Cu(I) state. In the Cu(I) state, the G89 loop is in the “closed” conformation with a confined copper center, which could allow for efficient O2 binding. In addition, the G89 loop remains in the “closed” conformation in the Cu(II)-superoxo intermediate, which could prevent off-pathway superoxide release via exchange with the distal aqueous ligand. Finally, at the end of the reaction cycle, aqueous ligand binding to the distal site could switch the G89 loop to the “open” conformation and facilitate product release

Distal Hydrophobic Loop Modulates the Copper Active Site and Reaction of AA13 Polysaccharide Monooxygenases

Polysaccharide monooxygenases (PMOs) use a type-2 copper center to activate O2 for the selective hydroxylation of one of the two C–H bonds of glycosidic linkages. Our electron paramagnetic resonance (EPR) analysis and molecular dynamics (MD) simulations suggest the unprecedented dynamic roles of the loop containing the residue G89 (G89 loop) on the active site structure and reaction cycle of starch-active PMOs (AA13 PMOs). In the Cu(II) state, the G89 loop could switch between an “open” and “closed” conformation, which is associated with the binding and dissociation of an aqueous ligand in the distal site, respectively. The conformation of the G89 loop influences the positioning of the copper center on the preferred substrate of AA13 PMOs. The dissociation of the distal ligand results in the bending of the T-shaped core of the Cu(II) active site, which could help facilitate its reduction to the active Cu(I) state. In the Cu(I) state, the G89 loop is in the “closed” conformation with a confined copper center, which could allow for efficient O2 binding. In addition, the G89 loop remains in the “closed” conformation in the Cu(II)-superoxo intermediate, which could prevent off-pathway superoxide release via exchange with the distal aqueous ligand. Finally, at the end of the reaction cycle, aqueous ligand binding to the distal site could switch the G89 loop to the “open” conformation and facilitate product release

Diversity of Fusarium associated banana wilt in northern Viet Nam

Fusarium is one of the most important fungal genera of plant pathogens that affect the cultivation of a wide range of crops. Agricultural losses caused by Fusarium oxysporum f. sp. cubense (Foc) directly affect the income, subsistence, and nourishment of thousands of farmers worldwide. For Viet Nam, predictions on the impact of Foc for the future are dramatic, with an estimated loss in the banana production area of 8% within the next five years and up to 71% within the next 25 years. In the current study, we applied a combined morphological-molecular approach to assess the taxonomic identity and phylogenetic position of the different Foc isolates collected in northern Viet Nam. In addition, we aimed to estimate the proportion of the different Fusarium races infecting bananas in northern Viet Nam. The morphology of the isolates was investigated by growing the collected Fusarium isolates on four distinct nutritious media (PDA, SNA, CLA, and OMA). Molecular phylogenetic relationships were inferred by sequencing partial rpb1, rpb2, and tef1a genes and adding the obtained sequences into a phylogenetic framework. Molecular characterization shows that c. 74% of the Fusarium isolates obtained from infected banana pseudostem tissue belong to F. tardichlamydosporum. Compared to F. tardichlamydosporum, F. odoratissimum accounts for c.10% of the Fusarium wilt in northern Viet Nam, demonstrating that Foc TR4 is not yet a dominant strain in the region. Fusarium cugenangense – considered to cause Race 2 infections among bananas – is only found in c. 10% of the tissue material that was obtained from infected Vietnamese bananas. Additionally, one of the isolates cultured from diseased bananas was phylogenetically not positioned within the F. oxysporum species complex (FOSC), but in contrast, fell within the Fusarium fujikuroi species complex (FFSC). As a result, a possible new pathogen for bananas may have been found. Besides being present on several ABB ‘Tay banana’, F. tardichlamydosporum was also derived from infected tissue of a wild Musa lutea, showing the importance of wild bananas as a possible sink for Foc