Study of the morphology of the low-latitude D region ionosphere using the method of tweeks observed at Buon Ma Thuot, Dak Lak

Tweek is the electromagnetic waves at Extremely Low Frequency (3 - 3000 Hz) and Very Low Frequency (3-30 kHz) bands, which originates from lightning discharges and propagates about thousands of kilometers in the Earth-Ionosphere waveguide. Recording the tweeks with a maximum up to eighth harmonics using the receiver installed at Tay Nguyen University (12.65oN, 108.02oE), Buon Ma Thuot, Dak Lak, during January - June 2013, we have studied the morphology of the low-latitude D region ionosphere in the nighttime. The occurrence of  tweeks with mode number m = 2 - 3 is more dominant. Tweeks with higher modes (m ≥ 4) appear less than other tweeks due to the higher attenuation of wave energy for higher modes reflected at the ionospheric D region. The results show that electron density varies from 25.1-189.4 cm-3, corresponding to the tweeks with m = 1-8 at the reflection height from 82.2-86.5 km. The reference height h’ and electron density gradient β are higher during summer seasons as compared to those during winter and equinox seasons. The mean values of h’ and β are 82.5 km and 0.53 km-1, respectively. The electron density using the tweek method is lower by about 11-38 % than those obtained using the IRI-2012 model.References Bremer, J. and Singer W., 1977. Diurnal, seasonal, and solar-cycle variations of electron densities in the ionospheric D and E region, J. Atmos. Terr. Phys., 39,  25-34. Budden, K. G., 1961. The Wave-Guide Mode Theory of Wave Propagation, Logos Press, London, pp. 325. Budden, K. G., 1962: The influence of the earth’s magnetic field on radio propagation of wave-guide modes. Proceedings of the Royal Society A, 265, 538-553. Cannam, C., Landone C., and Sandler M., 2010. Sonic Visualiser: An Open Source Application for Viewing, Analysing, and Annotating Music Audio Files. Proceedings of the ACM Multimedia 2010 International Conference. Danilov, A. D., 1998. Solar activity effects in the ionospheric D region, Ann. Geophys., 16, 1527-1533. Davies, K., 1965. Ionospheric Radio Propagation, National Bureau of Standard Monogragh 80, Washington, pp. 487. Hargreaves, J. K., 1992. The Solar-Terrestrial Environment, Cambridge Univ. Press, pp. 420. Heaps, M. G., 1978. Parameterization of the cosmic ray ion-pair production rate above 18 km, Planet. Space Sci., 26, 513-517. Helliwell, R. A., 1965. Whistlers and Related Ionospheric Phenomena, Stanford University Press, USA, pp. 368 Inan, U. S., Cummer, S. A., and Marshall, R. A., 2010. A survey of ELF and VLF research on lightning-ionosphere interactions and causative discharges, J. Geophys. Res., 115, A00E36. Kumar, S., Deo A., and Ramachandran V., 2009: Nightime D-region equivalent electron density determined from tweek sferics observed in the South Pacific Region, Earth Planets Space, 61, 905-911. Kumar, S., Kishore A., and Ramachandran V., 2008. Higher  harmonic  tweek  sferics  observed  at  low  latitude:  estimation  of  VLF  reflection  heights  and  tweek propagation distance,  Ann. Geophys, 26, 1451-1459. Le Huy Minh, Tran Thi Lan, C. Amory -Mazaudier, R. Fleury, A. Bourdillon, J. Hu, Vu Tuan Hung, Nguyen Chien Thang, Le Truong Thanh, Nguyen Ha Thanh, 2016. Continuous GPS network in Vietnam and results of study on the total electron content in the Southeast Asian region, Vietnam Journal of  Earth Sci.,  38 (2), doi: 10.15625/0866-7187/38/2/8598. Maurya, A. K., Veenadhari, B., Singh, R., Kumar, S., et al., 2012. Nighttime D region electron density measurements from ELF-VLF tweek radio atmospherics recorded at low latitudes, J. Geophys. Res., 117. Ohya, H., Nishino M., Murayama Y., and Igarashi K., 2003. Equivalent electron density at reflection heights of tweek atmospherics in the low - middle latitude D-region ionosphere, Earth Planets Space, 55, 627-635. Ohya, H., Nishino, M., Murayama, Y., Igarashi, K., 1981. Effects of land and sea parameters on the dispersion of tweek atmospherics, J. Atmos. Terr. Phys. 43, 1271-1277. Ohya, H., Shiokawa K., and Miyoshi Y., 2008. Development of an automatic procedure to estimate the reflection height of tweek atmospherics, Earth Planets Space, 60, 837-843. Prasad, R., 1981. Effects of land and sea parameters on the dispersion of tweek atmospherics, J. Atmos. Terr. Phys., 43, 1271-1273, 1275-1277. Saini, S. and Gwal A. K., 2010. Study of variation in the lower ionospheric reflection height with polar day length at Antarctic station Maitri: Estimated with tweek atmospherics, J. Geophys. Res., 115, A05302. Shariff, K.K.M., Salut, M. M., Abdullah, M., and Graf, K. L. 2011. Investigation of the D-region ionosphere characteristics using tweek atmospherics at low latitudes.  Proceeding of the 2011 IEEE International Conference on Space Science and Communication, 12-13 July 2011, Penang, Malaysia. Shvets, A. V., and Hayakawa M., 1998. Polarization effects for tweek propagation. J. Atmos. Terr. Phys., 60, 461- 469. Tan, L. M., Thu, N. N., Ha, T. Q., 2014. Observation of the effects of solar flares on the NWC signal using the new VLF receiver at Tay Nguyen University, Sun Geosphere, 8, 27-31. Wait, J. R. and Spies K. P., 1964. Characteristics of the Earth-ionosphere waveguide for VLF radio waves. NBS Tech. Not.,  pp.300. Wood, G. T., 2004. Geo-loaction of individual lightning discharges using impulsive VLF electromagnetic waveforms. Ph.D. Thesis, Stanford University. Yamashita, M., 1978. Propagation of tweek atmospherics. J. Atmos. Terr. Phys., 40, 151-153, 155-156. http://www.ultramsk.com/software

Hemorrhagic Meningioma With Symptom of Convulsion: A Rare Presentation of Parietal Meningioma

Meningioma is the most common, extra-axial, non-glial intracranial tumor with an incidence of 2.3-5.5/100 000, accounting for 20%-30% of all primary brain tumor diagnoses in adults. Meningiomas associated with intratumoral hemorrhage are very rare occurring in 0.5%-2.4%. of individuals. Herein, we report a rare case of hemorrhagic meningioma with the symptom of convulsion. The case was a 68-year-old woman admitted to the hospital with severe headache and convulsions. Computed tomography revealed an increase in heterogeneous lesion measuring 4 × 3 × 2.5 cm at the right parietal lobe. Brain magnetic resonance imaging (MRI) showed a grossly stable homogeneously enhancing extra-axial mass measuring 43 × 33 × 28 mm, small calcified peripheral, intratumoral hemorrhage. Histopathology showed a multi-celled meningioma with bleeding areas (WHO grade I)

Enzimatska obrada iskorištenih listića zelenog čaja i njihova primjena u proizvodnji čajnog peciva s velikim udjelom prehrambenih vlakana

Research background. By-products of food industry have been studied as sources of high fibre and antioxidant ingredients for healthy food products, because of their economic and environmental benefits. However, the soluble dietary fibre content of these materials is usually lower than the recommended value that is claimed to bring positive health effects. Enzymatic treatment could be an efficient method for modifying insoluble and soluble dietary fibre contents of these materials. The purpose of this study is to investigate the effects of enzymatic treatment conditions on soluble, insoluble and total dietary fibre mass fractions in spent green tea leaves, and evaluate the quality of dough and cookies when different mass fractions of untreated and treated leaves were added to the recipe. Experimental approach. The mass fractions of soluble, insoluble and total dietary fibre in spent tea leaf powder was evaluated after the leaves were treated with cellulase amount of 0−25 U/g for 0 to 2 h. Wheat flour was replaced by untreated and treated spent tea leaf powder at 0, 10, 20, 30 and 40% in cookie formulation. Textural properties of dough, proximate composition, physical properties and overall acceptability of cookies were analysed. Results and conclusions. The appropriate conditions for enzymatic treatment were enzyme loading of 20 U/g and biocatalytic time of 1.5 h, under which the mass fraction of soluble dietary fibre in spent tea leaves increased by 144.5% compared to that of the control sample. The addition of spent tea leaves led to the increase in dough hardness. Increase in the spent tea leaf amount also enhanced fibre mass fraction, antioxidant activity and hardness of cookies but reduced their overall acceptability. Moreover, the enzymatic treatment of spent tea leaves improved the soluble to total dietary fibre ratio of the cookies, which influenced their textural properties and health benefits. The cookies with added 20% untreated or treated spent tea leaves were overall accepted by the panel. Novelty and scientific contribution. For the first time, spent tea leaves have been treated with enzymes to improve their soluble to total dietary fibre ratio. The treated spent tea leaves are a new promising high-fibre antioxidant ingredient for cookie preparation.Pozadina istraživanja. Nusproizvodi prehrambene industrije ispituju se iz ekonomskih i ekoloških razloga kao izvori sastojaka s velikim udjelom prehrambenih vlakana i antioksidacijskim učinkom koji se mogu upotrijebiti u proizvodnji zdrave hrane. Međutim, udjel topljivih prehrambenih vlakana u nusproizvodima je obično manji od preporučenih vrijednosti koje mogu imati pozitivan učinak na zdravlje. Enzimatska obrada bi mogla biti učinkovita metoda modificiranja netopljivih i topljivih prehrambenih vlakana iz otpada prehrambene industrije. Svrha je ovog rada bila ispitati utjecaj različitih uvjeta enzimatske obrade na masene udjele topljivih, netopljivih i ukupnih prehrambenih vlakana u iskorištenim listićima zelenog čaja, te procijeniti kakvoću tijesta i čajnog peciva s dodatkom različitih masenih udjela obrađenih i neobrađenih listića. Eksperimentalni pristup. Maseni udjeli topljivih, netopljivih i ukupnih prehrambenih vlakana u prahu od iskorištenih listića zelenog čaja mjereni su nakon njihove obrade s 0–25 U/g celulaze tijekom 0 do 2 h. U smjesi za čajno pecivo je pšenično brašno zamijenjeno s 0, 10, 20, 30 i 40 % obrađenog ili neobrađenog praha iskorištenih listića zelenog čaja. Ispitani su tekstura tijesta te kemijski sastav, fizikalna svojstva i ukupna prihvatljivost dobivenog čajnog peciva. Rezultati i zaključci. Pri povoljnim uvjetima enzimatske obrade, a to su 20 U/g enzima i vrijeme trajanja biokatalitičkog procesa od 1,5 sata, maseni udjel topljivih prehrambenih vlakana u iskorištenim listićima zelenog čaja porastao je za 144,5 % u usporedbi s kontrolnim uzorkom. Dodatkom iskorištenih listića zelenog čaja povećala se tvrdoća tijesta. Povećanjem količine listića čaja povećali su se i maseni udjel vlakana, antioksidacijska svojstva i tvrdoća čajnog peciva, ali se smanjila njihova prihvatljivost. Osim toga, enzimatskom se obradom iskorištenih listića zelenog čaja poboljšao omjer topljivih i ukupnih vlakana u čajnom pecivu, što je utjecalo na njegovu teksturu i pozitivan učinak na zdravlje. Panel ocjenjivača je okarakterizirao čajno pecivo s dodatkom 20 % obrađenih ili neobrađenih iskorištenih listića čaja kao prihvatljive. Novina i znanstveni doprinos. Prvi put je enzimatskom obradom iskorištenih listića zelenog čaja poboljšan njihov omjer topljivih i ukupnih prehrambenih vlakana. Obrađeni iskorišteni listići zelenog čaja novi su obećavajući sastojak s antioksidacijskim svojstvima koji se može upotrijebiti u pripremi čajnog peciva

Chemical composition and antimicrobial activity of the essential oil from twigs and leaves of Magnolia macclurei (Dandy) Figlar from Ha Giang Province, Vietnam

The chemical composition of the essential oil obtained by hydrodistillation of the twigs and leaves of Magnolia macclurei collected in Hoang Su Phi, Ha Giang Province, Vietnam was analyzed using GC/MS. A total of 38 compounds were detected in essential oil, accounting for 94.49% of the oil, in which 37 compounds were identified accounting for 93.33%. cis-β-Elemene (14,30%), bicyclogermacrene (18,57%), and 10-epi-ᵧ-eudesmol (16,86%) were the main components of essential oil. The minor components present with rather high amount were: Germacrene D (2,12%), guaiol (8,52%), hinesol (2,34%), valerianol (6,76%), and bulnesol (2,93%). Antibiotic activity of the essential oil sample was tested against a Gram positive bacteria Staphylococcus aureus, a Gram negative bacteria Escherichia coli, and a yeast Candida albicans using an agar disk diffusion method. All three microorganisms tested are resistant to the oil from twigs and leaves of M. macclurei. That is exhibited through the inhibitory zone diameters ranging from 4 to 12 mm

Beyond the homestay: women’s participation in rural tourism development in Mekong Delta, Vietnam

This study examines the impact of the homestay tourism program in Mekong Delta, Vietnam, on women’s participation and empowerment in rural tourism development. As part of this study, 22 interviews were conducted with homestay owners to explore the benefits and challenges of women’s involvement in this type of tourism. The findings show that homestay tourism program has helped women to generate extra income, strengthen family ties, and increase their social influence while reducing domestic violence. However, cultural expectations and gender roles continue to pose challenges. This study underscores the importance of women’s participation in homestay tourism program and provides suggestions for promoting gender equality and women’s empowerment in tourism development. The study highlights the potential of women’s involvement in creating a sustainable and inclusive tourism industry and calls for further research and action to promote gender equality and women’s rights in tourism. The findings have practical implications for policymakers and practitioners in the tourism sector

Direct and indirect costs of smoking in Vietnam

This study was designed to overcome limitations of two previous investigations by calculating both direct and indirect health costs of five smoking-related diseases that are responsible for almost 75% of all smoking-related deaths in Vietnam: lung cancer, cancers of the upper aerodigestive tract, chronic obstructive pulmonary disease, ischaemic heart disease and stroke. Understanding the healthcare system is crucial for calculating the actual cost of smoking in Vietnam. The total estimated economic cost of smoking for five smoking-related diseases was 24 679.9 billion VND (US$1173.2 million), not taking into account exposure to second hand smoke

COMPARISON EFFICACY OF ITS AND 18S rDNA PRIMERS FOR DETECTION OF FUNGAL DIVERSITY IN COMPOST MATERIAL BY PCR-DGGE TECHNIQUE

Through composting process, biosolid wastes are gradually transformed into compost material which can be used as soil fertilizer. Among microorganisms involved in composting process, fungi play important roles because they break down complex substrates, such as ligno-cellulose. Recently, PCR-DGGE technique has been considered as a useful tool for analysis of fungal diversity in environmental samples. Among other factors, primer set selection is necessary for successful of the PCR-DGGE analysis. There are several PCR primer sets targeting fungal variable regions of 18S ribosomal DNA (rDNA) and internal transcribed spacer (ITS) for the use in community analyses, however there exist just few reports on efficacy of these primers in studying fungal communities in compost materials. In this study, four different primer sets were tested, including EF4/Fung5 (followed by EF4/NS2-GC), EF4/ITS4 (followed by ITS1F-GC/ITS2), NS1/GC-Fung, and FF390/FR1-GC. Extracted DNA from compost materials often contains co-extracted humic substances and other PCR inhibitors. Therefore, the primers were tested for (i) tolerance to the PCR inhibitors presenting in the DNA extracted from compost materials, and (ii) efficacy and specificity of the PCR. The results showed that of the four primer sets, only FF390/FR1-GC achieved both criteria tested whereas the other three did not, i.e. primer EF4/ITS4 had low tolerance to PCR inhibitors, primers EF4/Fung5 was low in PCR amplification efficacy, whereas primers EF4/ITS4 created unspecific products. DGGE analyses of PCR products amplified with the primer set FF390/FR1-GC showed single bands for reference pure cultures Penicillium sp., Aspergillus sp., and Trichoderma sp., as well as distinctly separated bands for the fungal communities of three different composting materials. Thus, the primer set FF390/FR1-GC could be suitable for studying structure and dynamic of fungal communities in compost materials

A prospective multi-center observational study of children hospitalized with diarrhea in Ho Chi Minh City, Vietnam.

We performed a prospective multicenter study to address the lack of data on the etiology, clinical and demographic features of hospitalized pediatric diarrhea in Ho Chi Minh City (HCMC), Vietnam. Over 2,000 (1,419 symptomatic and 609 non-diarrheal control) children were enrolled in three hospitals over a 1-year period in 2009-2010. Aiming to detect a panel of pathogens, we identified a known diarrheal pathogen in stool samples from 1,067/1,419 (75.2%) children with diarrhea and from 81/609 (13.3%) children without diarrhea. Rotavirus predominated in the symptomatic children (664/1,419; 46.8%), followed by norovirus (293/1,419; 20.6%). The bacterial pathogens Salmonella, Campylobacter, and Shigella were cumulatively isolated from 204/1,419 (14.4%) diarrheal children and exhibited extensive antimicrobial resistance, most notably to fluoroquinolones and third-generation cephalosporins. We suggest renewed efforts in generation and implementation of policies to control the sale and prescription of antimicrobials to curb bacterial resistance and advise consideration of a subsidized rotavirus vaccination policy to limit the morbidity due to diarrheal disease in Vietnam

Pathogenic Escherichia coli Possess Elevated Growth Rates under Exposure to Sub-Inhibitory Concentrations of Azithromycin.

Antimicrobial resistance (AMR) has been identified by the World Health Organization (WHO) as one of the ten major threats to global health. Advances in technology, including whole-genome sequencing, have provided new insights into the origin and mechanisms of AMR. However, our understanding of the short-term impact of antimicrobial pressure and resistance on the physiology of bacterial populations is limited. We aimed to investigate morphological and physiological responses of clinical isolates of E. coli under short-term exposure to key antimicrobials. We performed whole-genome sequencing on twenty-seven E. coli isolates isolated from children with sepsis to evaluate their AMR gene content. We assessed their antimicrobial susceptibility profile and measured their growth dynamics and morphological characteristics under exposure to varying concentrations of ciprofloxacin, ceftriaxone, tetracycline, gentamicin, and azithromycin. AMR was common, with all organisms resistant to at least one antimicrobial; a total of 81.5% were multi-drug-resistant (MDR). We observed an association between resistance profile and morphological characteristics of the E. coli over a three-hour exposure to antimicrobials. Growth dynamics experiments demonstrated that resistance to tetracycline promoted the growth of E. coli under antimicrobial-free conditions, while resistance to the other antimicrobials incurred a fitness cost. Notably, antimicrobial exposure heterogeneously suppressed bacterial growth, but sub-MIC concentrations of azithromycin increased the maximum growth rate of the clinical isolates. Our results outline complex interactions between organism and antimicrobials and raise clinical concerns regarding exposure of sub-MIC concentrations of specific antimicrobials

Isolation and characterization of Rhizobium spp. and Bradyrhizobium spp. from legume nodules

Rhizobia topic has been re-focused in recent years because of new findings on their traits not only as nitrogen-fixing bacteria but also as plant growth-promoting rhizobacteria. When combing rhizobial strains with novel biological carriers (e.g., biochar) for inoculant production, it brings great potential for improving soil health in long-term. Appreciating this trend, this study is designed to isolate and characterize local rhizobial strains from legume fields using the conventional method with some modifications to increase efficiency in rhizobial identification. As a result, 17 rhizobial strains were isolated and classified biochemically that genetic identification outcome confirmed 10 strains belong to 07 different Rhizobium species as R. mayense, R. paknamense, R. pusense, R. miluonense, R. tropici, R. phaseoli, and R. multihospitium while the rest belong to 06 various Bradyrhizobium species as B. elkanii, B. centrosematis, B. guangxiense, B. liaoningense, B. yuanmingense, and B. arachidis. Thermal and saline tolerant tests together with seed germination tests also performed on these rhizobial strains to gain data on their responses to abiotic stresses. By comparing rice and mung bean GI values, we can assess the effectiveness of each rhizobial strains to help seeds at their early germination