46 research outputs found

    Distributed opportunistic scheduling algorithms for wireless communications.

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    In this thesis, we propose a number of distributed schemes for wireless communications in the cross layer design context, considering an uplink random access network in which multiple users communicate with a common base station. In addition, we perform a comprehensive study on a splitting based multiuser selection algorithm which is simple, effective, and scales with the network size. First, we investigate a reservation-type protocol in a channel aware ALOHA system. Various Markovian models are used to describe the system and to capture the temporal correlation of the channel evolution. The average throughput of the system is obtained using the Markov Analysis technique and we show that the reservation protocol can achieve better performance than the original channel-aware ALOHA by reducing the collision probability. Second, for better resource utilization in the Opportunistic Multichannel ALOHA scheme, we propose a simple extension to the transmission policy that exploits the idle channels. Performance analysis shows that, theoretically, the maximum system throughput can be improved by up to 63% in the asymptotic case. Through numerical results, it can be seen that a significant gain is achieved even when the system consists of a small number of users. Third, we consider a splitting based multiuser selection algorithm in a probabilistic view. Asymptotic analysis leads to a functional equation, similar to that encountered in the analysis of the collision resolution algorithm. Subject to some conditions, the solution of the functional equation can be obtained, which provides the approximations for the expected number of slots and the expected number of transmissions required by the algorithm in a large system. These results shed light on open design problems in choosing parameters for the algorithm when considering the delay and the overhead jointly. A typical example is to optimize the parameters that minimize the weighted sum of these measures of interest

    Multi-faceted insights of entrepreneurship facing a fast-growing economy: A literature review

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    This study explores entrepreneurship research in Vietnam, a lower-middle-income country in Southeast Asia that has witnessed rapid economic growth since the 1990s but has nonetheless been absent in the relevant Western-centric literature. Using an exclusively developed software, the study presents a structured dataset on entrepreneurship research in Vietnam from 2008 to 2018, highlighting: low research output, low creativity level, inattention to entrepreneurship theories, and instead, a focus on practical business matters. The scholarship remains limited due to the detachment between the academic and entrepreneur communities. More important are the findings that Vietnamese research on entrepreneurship, still in its infancy, diverges significantly from those in developed and emerging economies in terms of their content and methods. These studies are contextualized to a large extent to reflect the concerns of a developing economy still burdened by the high financial and nonfinancial costs

    On how religions could accidentally incite lies and violence: Folktales as a cultural transmitter

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    This research employs the Bayesian network modeling approach, and the Markov chain Monte Carlo technique, to learn about the role of lies and violence in teachings of major religions, using a unique dataset extracted from long-standing Vietnamese folktales. The results indicate that, although lying and violent acts augur negative consequences for those who commit them, their associations with core religious values diverge in the final outcome for the folktale characters. Lying that serves a religious mission of either Confucianism or Taoism (but not Buddhism) brings a positive outcome to a character (βT_and_Lie_O= 2.23; βC_and_Lie_O= 1.47; βT_and_Lie_O= 2.23). A violent act committed to serving Buddhist missions results in a happy ending for the committer (βB_and_Viol_O= 2.55). What is highlighted here is a glaring double standard in the interpretation and practice of the three teachings: the very virtuous outcomes being preached, whether that be compassion and meditation in Buddhism, societal order in Confucianism, or natural harmony in Taoism, appear to accommodate two universal vices—violence in Buddhism and lying in the latter two. These findings contribute to a host of studies aimed at making sense of contradictory human behaviors, adding the role of religious teachings in addition to cognition in belief maintenance and motivated reasoning in discounting counterargument

    Factors affecting the competition of an irrigation construction project using state budget funds

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    The objective of this paper is to evaluate factors affecting the progress of completing construction of irrigation projects using state budget funds. To achieve the goal, to research and conduct surveys of investors, contractors, managers of irrigation construction investment projects. Analysis results from 269 valid questionnaires using SmartPLS 3.6 software showed that all 6 factors: Investor, Peripheral, Capital, Contractors, Consultant, Convenience, all factors have a positive impact on progress of completing irrigation construction projects using state budget funds in Thai Binh province, Vietnam

    Policy Response, Social Media and Science Journalism for the Sustainability of the Public Health System Amid the COVID-19 Outbreak: The Vietnam Lessons

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    Vietnam, with a geographical proximity and a high volume of trade with China, was the first country to record an outbreak of the new Coronavirus disease (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus 2 or SARS-CoV-2. While the country was expected to have a high risk of transmission, as of April 4, 2020—in comparison to attempts to contain the disease around the world—responses from Vietnam are being seen as prompt and effective in protecting the interests of its citizens, with 239 confirmed cases and no fatalities. This study analyzes the situation in terms of Vietnam’s policy response, social media and science journalism. A self-made web crawl engine was used to scan and collect official media news related to COVID-19 between the beginning of January and April 4, yielding a comprehensive dataset of 14,952 news items. The findings shed light on how Vietnam—despite being under-resourced—has demonstrated political readiness to combat the emerging pandemic since the earliest days. Timely communication on any developments of the outbreak from the government and the media, combined with up-to-date research on the new virus by the Vietnamese science community, have altogether provided reliable sources of information. By emphasizing the need for immediate and genuine cooperation between government, civil society and private individuals, the case study offers valuable lessons for other nations concerning not only the concurrent fight against the COVID-19 pandemic but also the overall responses to a public health crisis

    Agrobacterium-mediated transformation of Nang Thom Cho Dao, an indica rice variety

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    Agrobacterium-mediated transformation is the most efficient method to transfer gene of interest into the plant genome. However, the transformation efficiency of this method with indica rice varieties is still low and needs to be improved. In this study, the Agrobacterium-mediated method was used to transfer reporter genes into the Nang Thom Cho Dao, an indica rice variety. Different transformation parameters, such as selection to used hygromycin at concentrations of 0, 25, 30, 40, and 50 mg/L, bacterial density, and infected duration, were tested and optimized. The results showed that 30 mg/L of hygromycin was the most appropriate concentration for selecting transgenic callus in Nang Thom Cho Dao. In addition, the highest transformation efficiency of this Nang Thom Cho Dao rice cultivar was observed at the bacterial suspension density OD600nm of 0.1, the infected duration of 20 minutes, and the 3-day co-culture period. The presence and expression of transgenes were confirmed by gus staining and PCR with specific primers for hptII and gus genes. This transformation procedure should be used for further studies in genetic engineering of Nang Thom Cho Dao and other indica rice varieties

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

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    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

    Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

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    Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

    Vegetarian market research in Southern Ho Chi Minh City : First step to open a vegetarian restaurant

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    People are more and more aware of their health care, they go exercising more often, take healthy food, and avoid harmful intake such as sugar, red meat, processed food, etc. Vegetarian food is widely spoken as a healthy diet and eco-friendly. Vietnamese also goes with the trend, especially among the youth. There is already a good vegetarian community in Vietnam, especially Ho Chi Minh City. The market is growing, there are new vegetarian restaurants with good investment in design, theme, and food. They are still crowded, meaning that the offer can be low, especially in Southern area of Ho Chi Minh city, where the thesis focused on. The writer has been interested in the diet for 3 years, now he wants to join and explore the market. However, there is not much information about people diet habit in Vietnam, how they aware of vegetarian food and restaurants, as well as their favor in choosing eating place. Hence, this thesis aimed to research about the people’s behaviors in their diet as well as opinions on vegetarian in Southern Ho Chi Minh City. The target audience is office employees, as the thesis writer found some problems that he wants to solve. The thesis was structured with 5 main parts. First thing first, all the information and background of this thesis in details. Then it comes to the theoretical chapter with related theories and information from books, organizations, or journals, etc. Third part is the research, containing 3 parts: Benchmarking vegetarian restaurants, including 1 restaurants observation; a Questionnaire survey among 142 office employees in Southern Ho Chi Minh City, mainly District 7 and Nha Be; and Result analysis. The number 5 chapter will conclude all the findings along with suggestions for the next step of opening the restaurant. All the sources are listed at Reference Chapter, and the Questionnaire is shown at the Appendix 2

    Energy efficient distributed beamforming with sensor selection in wireless sensor networks

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