Index-Model inference with Box-Cox transformations

The single-index model is a non-parametric model that is popular in statistics for the estimation of risk assessment, thanks to its flexibility. Many studies have approached the problem of finding the best estimators for the model parameters and smooth function. However, most of the real-world data is asymmetric. In this thesis, we consider the application of a Box-Cox transformation on the response variable to improve the performances of the single-index model. Indeed, the Box-Cox transformation addresses the skewness of the response and transform it into a normally-distributed variables. We consider also the log transformation of the response variable. We show through a simulation study that the parameters of the models fitted with the transformed response have more similarity with the true parameters, which shows that the model is more reliable. Finally, we perform a study on a real-world data set from the car insurance industry, where we build a single-index model to predict the expected cost per claim based on a set of variables, that concern the demographic characteristic and the driving style of the customer. We assess the performance of the model fitted on the original data as well the models that use the log and the Box-Cox transformation, that obtain better results than the original one

Characterizing DNA Condensation and Conformational Changes in Organic Solvents

Organic solvents offer a new approach to formulate DNA into novel structures suitable for gene delivery. In this study, we examined the in situ behavior of DNA in N, N-dimethylformamide (DMF) at low concentration via laser light scattering (LLS), TEM, UV absorbance and Zeta potential analysis. Results revealed that, in DMF, a 21bp oligonucleotide remained intact, while calf thymus DNA and supercoiled plasmid DNA were condensed and denatured. During condensation and denaturation, the size was decreased by a factor of 8–10, with calf thymus DNA forming spherical globules while plasmid DNA exhibited a toroid-like conformation. In the condensed state, DNA molecules were still able to release the counterions to be negatively charged, indicating that the condensation was mainly driven by the excluded volume interactions. The condensation induced by DMF was reversible for plasmid DNA but not for calf thymus DNA. When plasmid DNA was removed from DMF and resuspended in an aqueous solution, the DNA was quickly regained a double stranded configuration. These findings provide further insight into the behavior and condensation mechanism of DNA in an organic solvent and may aid in developing more efficient non-viral gene delivery systems

Low-Level Vibrations Retain Bone Marrow's Osteogenic Potential and Augment Recovery of Trabecular Bone during Reambulation

Mechanical disuse will bias bone marrow stromal cells towards adipogenesis, ultimately compromising the regenerative capacity of the stem cell pool and impeding the rapid and full recovery of bone morphology. Here, it was tested whether brief daily exposure to high-frequency, low-magnitude vibrations can preserve the marrow environment during disuse and enhance the initiation of tissue recovery upon reambulation. Male C57BL/6J mice were subjected to hindlimb unloading (HU, n = 24), HU interrupted by weight-bearing for 15 min/d (HU+SHAM, n = 24), HU interrupted by low-level whole body vibrations (0.2 g, 90 Hz) for 15 min/d (HU+VIB, n = 24), or served as age-matched controls (AC, n = 24). Following 3 w of disuse, half of the mice in each group were released for 3 w of reambulation (RA), while the others were sacrificed. RA+VIB mice continued to receive vibrations for 15 min/d while RA+SHAM continued to receive sham loading. After disuse, HU+VIB mice had a 30% greater osteogenic marrow stromal cell population, 30% smaller osteoclast surface, 76% greater osteoblast surface but similar trabecular bone volume fraction compared to HU. After 3 w of reambulation, trabecular bone of RA+VIB mice had a 30% greater bone volume fraction, 51% greater marrow osteoprogenitor population, 83% greater osteoblast surfaces, 59% greater bone formation rates, and a 235% greater ratio of bone lining osteoblasts to marrow adipocytes than RA mice. A subsequent experiment indicated that receiving the mechanical intervention only during disuse, rather than only during reambulation, was more effective in altering trabecular morphology. These data indicate that the osteogenic potential of bone marrow cells is retained by low-magnitude vibrations during disuse, an attribute which may have contributed to an enhanced recovery of bone morphology during reambulation

Determinants of customer's apartment purchase intention: is the location dominant?

The purpose of this research is to identify and measure the factors affecting the intention to buy apartments of customers in Ho Chi Minh City, Vietnam. The survey carried out with the participation of 200 customers. The authors explore five factors which affect customer's apartment purchase intention include location, features, brand, finance, and subjective norm. The result from Exploratory Factor Analysis (EFA) shows that location, features, finance, and subjective norm have a significant effect on the intention to buy customers' apartments. In which, location in Ho Chi Minh City context is the most influential factor, so, it strongly confirm the research of Adair et al. (1996), Clark et al. (2006), Daly et al. (2003), Kaynak and Stevenson (2007), Opoku and AbdulMuhmin (2010), Sengul et al. (2010), Tu and Goldfinch (1996), Xiao and Tan (2007) and Wang and Li (2006). The study also proposes some recommendations to increase the attractiveness of the apartment. What is more, developers, marketers, real estate policymakers can use the results of this research to understand the needs of customers better and satisfy customers

SEASONAL VARIATION OF PHYTOPLANKTON FUNCTIONAL GROUPS IN TUYEN LAM RESERVOIR, CENTRAL HIGHLANDS, VIETNAM

Seasonal changes in freshwater phytoplankton assemblages at Tuyen Lam Reservoir in the Central Highlands of Vietnam were classified into 23 functional groups based on physiological, morphological, and ecological characteristics. A total of 168 species were recorded during 10 surveys from 2015 to 2019 at 7 sampling sites, with Chlorophyta dominating in number of species. Phytoplankton abundance varied from 0.18×105 to 21.2×105 cells/L during the study period, mainly due to cyanobacteria. Seven of the 23 functional groups were considered to be dominant (relative density > 5%).  The dominant functional groups were groups M and G in the dry season and groups M, G, P, and E in the rainy season. Group M (Microcystis aeruginosa) was the most common in both seasons, while group P (Closterium, Staurastrum, Aulacoseira), group E (Dinobryon, Synura), and group G (Sphaerocystis, Eudorina) were more common in the rainy season. The Shannon diversity index (H¢) showed that phytoplankton communities were relatively diverse and that most of the study sites were lightly polluted. However, the ecological status has deteriorated at some locations due to the overgrowth of group M, leading to eutrophication in this reservoir. This study highlights the usefulness of functional groups in the study of seasonal changes in phytoplankton dynamics. Functional groups are applied for the first time at Tuyen Lam Reservoir and can be used to predict early-stage cyanobacterial blooms in future studies

Village Baseline Study – Site Analysis Report Ma village-Yen Binh district, Vietnam

Ma village, Vinh Kien commune, Yen Binh district, Yen Bai province has been selected to be one of Climate Smart Villages (CSVs) under the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS) in Southeast Asia. The village baseline survey (VBS) of Ma village, was therefore conducted as part of the baseline effort. This VBS aimed to provide baseline information at the village level about some basic indicators of natural resource utilization, organizational landscapes, and information networks for weather and agricultural information, which can be compared across sites and monitored over time. The study was conducted using the method developed and provided by CCAFS. The study’s findings show that Ma Village is rich and diverse in natural resources. There are three main resources of vital importance for the local people livelihoods, namely farmland, forest and water resources. However, improper exploitation and management have caused negative impacts on these resources. As mentioned by farmers, in the past, farmland of the village used to be very fertile, but has now become severely degraded due to overexploitation and improper management. Regarding forest resources: before 1980s, natural forests existed in large areas and consisted of valuable timber and wild animals. Today, much of the forest area has been converted to production forests or to food crop production land. Water resources, including lakes, rivers and streams have been severely polluted with pollutants from processing cassava, wood and also from animal husbandry and crop production. Degradation of water, farmland and forest resources are causing increasing challenges to agricultural production and also to other human activities. Results of farmer group discussions also demonstrate that there are 34 organizations operating in the village. Most of them are governmental. Very few are private or non-governmental organizations. The number of organizations involving in food security accounts for nearly 50%, the figure for those involving food crisis is 41.6% and in natural resources management is 25%. Those organizations working in food security and food crisis focus mainly on providing support (financial, seed and agricultural inputs) to local farmers to implement some production activities. Insufficient attention and input spent for sustainable development by these 34 organizations, especially those working in the area of natural resources management, could be one of the main reasons for the degradation and erosion of natural resources. There was no activity supporting Ma Village to develop production systems which can respond well to climate change. The study findings however show that local people are very flexible and creative, especially in exploitation of information. Among media channels, television is the most popular. Nevertheless, organizations, in particular, extension networks, Farmers’ Union, local authorities, etc., also have an important role in information dissemination. Exploitation of information from the internet and mobile phones has also been given attention, but mostly by young people only

Mechanical signals as anabolic agents in bone

Aging and a sedentary lifestyle conspire to reduce bone quantity and quality, decrease muscle mass and strength, and undermine postural stability, culminating in an elevated risk of skeletal fracture. Concurrently, a marked reduction in the available bone-marrow-derived population of mesenchymal stem cells (MSCs) jeopardizes the regenerative potential that is critical to recovery from musculoskeletal injury and disease. A potential way to combat the deterioration involves harnessing the sensitivity of bone to mechanical signals, which is crucial in defining, maintaining and recovering bone mass. To effectively utilize mechanical signals in the clinic as a non-drug-based intervention for osteoporosis, it is essential to identify the components of the mechanical challenge that are critical to the anabolic process. Large, intense challenges to the skeleton are generally presumed to be the most osteogenic, but brief exposure to mechanical signals of high frequency and extremely low intensity, several orders of magnitude below those that arise during strenuous activity, have been shown to provide a significant anabolic stimulus to bone. Along with positively influencing osteoblast and osteocyte activity, these low-magnitude mechanical signals bias MSC differentiation towards osteoblastogenesis and away from adipogenesis. Mechanical targeting of the bone marrow stem-cell pool might, therefore, represent a novel, drug-free means of slowing the age-related decline of the musculoskeletal system

Validation of Mesocyclops (Copepoda) and community participation as an effective combination for Dengue control in Northern Vietnam

The “Programme Meso-Vietnam” was implemented in Vietnam from October 2007 to December 2010 to reduce dengue and dengue hemorrhagic fever incidence and to improve the quality of life in the four project communes. This dengue control project was based on biological control using Mesocyclops, a larvivorous micro-crustacean, as well as on the establishment of a strong community involvement to educate the population on dengue transmission and to reduce Aedes breeding by removal of containers. During three years, a network of collaborators was responsible for introducing Mesocyclops in all the containers defined as key breeding-sites, and regular activities such as community training workshops, school programmes, clean-up campaigns and health promotion through IEC programmess were performed. To make this programme sustainable, local leadership has been strengthened as well. The use of these larvivorous micro-crustaceans as a biological control strategy against dengue over the medium and long term, when combined with community participation and effective health promotion, demonstrated a significant reduction in dengue vector populations and dengue cases.  In Vietnam, this study reconfirms that there is an ecological alternative to systematic use of insecticides to control dengue vector population. (Abstract word count: 186)Le " Programme Meso-Vietnam " a été mis en œuvre au Vietnam entre octobre 2007 et décembre 2010. Ce programme vise à réduire l'incidence de la dengue et de la fièvre hémorragique de la dengue et à améliorer la qualité de vie dans les quatre communes sélectionnées pour le projet. Ce projet de lutte contre la dengue était basé sur un contrôle biologique assuré par des Mésocyclopes, micro-crustacés larvivores, et sur l'établissement d'une forte implication de la communauté pour éduquer la population sur la transmission de la dengue et pour réduire la reproduction des moustiques Aedes par élimination des conteneurs leur servant de site de ponte. Pendant trois ans, un réseau de collaborateurs a été chargé d'introduire des Mésocyclopes dans tous les conteneurs définis comme des sites de reproduction clés, et des activités régulières telles que des ateliers de formation communautaires, des programmes scolaires, des campagnes de nettoyage et des activités de promotion de la santé via les programmes IEC ont été mises en place. En outre, pour assurer la pérennité de ce programme, le leadership local a été renforcé. L'utilisation de ces micro-crustacés larvivores comme stratégie de contrôle biologique de la dengue à moyen et long terme, associée à une participation communautaire et à une promotion efficace de la santé, a permis d'aboutir à une réduction significative des populations vecteurs de la dengue et des cas de dengue. Au Vietnam, cette étude confirme une fois de plus qu'il existe une alternative écologique à l'utilisation systématique d'insecticides pour lutter contre les vecteurs de la dengue.El “Programa Meso-Vietnam” se implementó en Vietnam desde octubre de 2007 hasta diciembre de 2010 para reducir la incidencia del dengue y la fiebre hemorrágica del dengue y para mejorar la calidad de vida en los cuatro municipios del proyecto. Este proyecto de control del dengue se basaba en el control biológico usando Mesocyclops, un microcrustáceo larvívoro, así como en el establecimiento de una fuerte implicación comunitaria para educar a la población sobre la transmisión del dengue y para reducir la cría de Aedes mediante la eliminación de recipientes. Durante tres años, una red de colaboradores fue responsable de la introducción de Mesocyclops en todos los recipientes definidos como sitios clave para la cría, y se realizaron actividades regulares tales como talleres de formación comunitaria, programas escolares, campañas de limpieza y promoción de la salud a través de programas de IEC. Para hacer sostenible este programa, también se reforzó el liderazgo local. El uso de estos microcrustáceos larvívoros como estrategia de control biológico contra el dengue a medio y largo plazo demostró una reducción significativa de las poblaciones de vectores del dengue y los casos de dengue cuando se combinaba con la participación comunitaria y la promoción eficaz de la salud. En Vietnam, este estudio vuelve a confirmar que existe una alternativa ecológica al uso sistemático de insecticidas para controlar la población de vectores del dengue