oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Achievements and Challenges in Molecular Conductors  [PDF]
Hidetoshi Fukuyama
Crystals , 2012, DOI: 10.3390/cryst2030875
Abstract: Molecular solids are generally highly insulating. The creation of conducting molecular solids proved to be a major scientific challenge. As in the case of Si technology, the challenge started as impurity doping in band insulators and then developed into highly doped polymers, which are not crystalline. More conducting materials in crystalline forms have been realized in charge transfer (CT) complexes with two different kinds of molecules, where electrons are transferred between them in solids. In such CT complexes, not only conducting, but also even superconducting systems were achieved in 1980 and today more than 100 different superconductors are known. The most remarkable achievement in this direction was the realization of a truly metallic state in molecular solids based on a single kind of molecule. These are called single component molecular metals (SCMM) and consist of a rich variety of electronic properties. In these conducting molecular solids, CT and SCMM, many interesting electronic properties resulting from mutual Coulomb interactions and electron-phonon interactions have been explored so far, and these will be reviewed briefly in this article from a theoretical viewpoint. Challenges to come, based on these achievements, are also discussed at the end of this review.
Molecular epidemiology of tuberculosis: methodology and applications
Burgos,Marcos V; Méndez,Juan Camilo; Ribon,Wellman;
Biomédica , 2004,
Abstract: the resurgence of tuberculosis around the world has renewed interest in understanding the epidemiology and pathogenesis of this disease. a revolutionary advance in the field of tuberculosis research has been the development of molecular techniques that permit identification and tracking of individual strains of mycobacterium tuberculosis. with these techniques, molecular epidemiology has been established as a new discipline that adds another dimension to the classical epidemiology of tuberculosis and has increased our understanding of the transmission dynamics of m. tuberculosis. the increased epidemiological knowledge has led to discovery of inadequacies in tuberculosis control programs; this information has helped garner resources for program improvement and has highlighted the need for the continuous surveillance of tuberculosis. additional genetic methods are being developed based on the knowledge of the genome sequence of m. tuberculosis. these simpler and less costly genotyping techniques promise to expand the application of molecular epidemiology to developing nations (where 90% of the disease burden occurs) in support of national tuberculosis programs. further more, these tools permit ever more effective probes into the dynamics of transmission, the population structure, evolution and pathogenesis of m. tuberculosis.
Epidemiology of anti-tuberculosis drug resistance in a chinese population: current situation and challenges ahead
Yan Shao, Dandan Yang, Weiguo Xu, Wei Lu, Honghuan Song, Yaoyao Dai, Hongbing Shen, Jianming Wang
BMC Public Health , 2011, DOI: 10.1186/1471-2458-11-110
Abstract: Strains were collected from 1824 diagnosed sputum smear positive pulmonary TB patients in Jiangsu province of China and then tested for drug susceptibility against rifampicin, isoniazid, ethambutol and streptomycin. The prevalence and patterns of drug resistance in mycobacterium tuberculosis (MTB) isolates were investigated. Multiple logistic regression analysis was performed to identify the risk factors for multidrug resistant (MDR) bacterial infection. The strength of association was estimated by odds ratio (OR) and 95% confidence interval (95% CI).The drug susceptibility tests showed that 1077(59.05%) MTB strains were sensitive to all the four antibiotics and the other 747(40.95%) strains were resistant to at least one drug. The proportions of mono-drug resistance were 28.73% for isoniazid, 19.41% for rifampicin, 29.33% for streptomycin, and 13.98% for ethambutol, respectively. The prevalence of MDR-TB was 16.61%, which was significantly different between new cases (7.63%) and those with previous treatment history (33.07%). Geographical variation of drug resistance was observed, where the proportion of MDR-TB among new cases was higher in the central (9.50%) or north part (9.57%) than that in the south area (4.91%) of Jiangsu province. The age of patients was significantly associated with the risk of drug resistance (P < 0.001) and the adjusted OR (95% CI) was 1.88(1.26-2.81) for patients aged 35-44 years when compared with those 65 years or older. Patients with previous treatment history had a more than 5-fold increased risk of MDR-TB (adjusted OR: 6.14, 95% CI: 4.61-8.17), compared with those previously not having been treated.The high prevalence of drug resistance has been a major challenge for TB control. Prevention and control of drug-resistant TB should be emphasized by the revised DOTS (direct observed therapy, short course) program through prompt case detection, routine and quality-assured drug susceptibility test for patients at high risk of resistance,
Investigación sobre epidemiología convencional y molecular de tuberculosis en Orizaba, Veracruz, 1995-2008
Jiménez-Corona,Ma Eugenia; García-García,Lourdes; León,Alfredo Ponce de; Bobadilla-del Valle,Miriam; Torres,Martha; Canizales-Quintero,Sergio; Palacios-Merino,Carmen; Molina-Hernández,Susana; Martínez-Gamboa,Rosa Areli; Juárez-Sandino,Luis; Cano-Arellano,Bulmaro; Ferreyra-Reyes,Leticia; Cruz-Hervert,Luis Pablo; Báez-Salda?a,Renata; Ferreira-Guerrero,Elizabeth; Sada,Eduardo; Marquina,Brenda; Sifuentes-Osornio,José;
Salud Pública de México , 2009, DOI: 10.1590/S0036-36342009000900013
Abstract: this study describes the achievements of the mexican consortium against tuberculosis, in the sanitary district of orizaba, veracruz, mexico between 1995 and 2008. in brief, the main results can be classified as follows: 1) conventional and molecular epidemiology (measurement of burden of disease, trends, risk factors and vulnerable groups, consequences of drug resistance, identification of factors that favor nosocomial and community transmission); 2) development of diagnostic techniques to detect drug resistance, description of circulating clones and adaptation of simple techniques to be used in the field; 3) evaluation of usefulness of tuberculin skin test, immunologic responses to bcg, impact of directly observed therapy for tuberculosis (dots), and study of immunological biomarkers and 4) comments on ethical aspects of tuberculosis research. additionally, we describe the impact on public policies, transference of technology, capacity building and future perspectives.
Database Research: Achievements and Challenges
Shan Wang,Xiao-Yong Du,Xiao-Feng Meng,Hong Chen,
Shan Wang
,Xiao-Yong Du,Xiao-Feng Meng,and Hong Chen

计算机科学技术学报 , 2006,
Abstract: Database system is the infrastructure of the modern information system. The R&D in the database system and its technologies is one of the important research topics in the field. The database R&D in China took off later but it moves along by giant steps. This report presents the achievements Renmin University of China (RUC) has made in the past 25 years and at the same time addresses some of the research projects we, RUC, are currently working on. The National Natural Science Foundation of China supports and initiates most of our research projects and these successfully conducted projects have produced fruitful results.
The Achievements and Challenges of Silicon Photonics  [PDF]
Richard Soref
Advances in Optical Technologies , 2008, DOI: 10.1155/2008/472305
Abstract: A brief overview of silicon photonics is given here in order to provide a context for invited and contributed papers in this special issue. Recent progress on silicon-based photonic components, photonic integrated circuits, and optoelectronic integrated circuits is surveyed. Present and potential applications are identified along with the scientific and engineering challenges that must be met in order to actualize applications. Some on-going government-sponsored projects in silicon optoelectronics are also described.
Epidemiología de la tuberculosis Epidemiology of tuberculosis  [cached]
M. C. Bermejo,I. Clavera,F. J. Michel de la Rosa,B. Marín
Anales del Sistema Sanitario de Navarra , 2007,
Abstract: La tuberculosis, "vieja conocida de la Neumología", constituye todavía una enfermedad con una alta morbimortalidad en el mundo lo que hace que, pese a estar en el siglo XXI, continúe recabando nuestra atención, se planteen grandes retos como el control de la misma y surgan nuevos problemas como la emergencia de la tuberculosis multirresistente. Así pues, constituye para la Organización Mundial de la Salud una enfermedad de gran interés que le ha llevado a desarrollar un programa específico y ambicioso que pretende su erradicación para el a o 2050. En este capítulo detallamos algunos de los aspectos más interesantes de la epidemiología de esta enfermedad, con una atención especial para el problema de la tuberculosis multirresistente y se exponen datos actualizados de la morbimortalidad tuberculosa en el mundo. Tuberculosis, that "old acquaintance of Pneumology", is still a disease with a high morbidity and mortality in the world. This is why, in spite of our having entered the XXI century, it continues to demand our attention, great challenges continue to be faced, such as bringing it under control, and new problems continue to arise, such as the emergence of multiresistant tuberculosis. Thus, for the World Health Organisation, it represents a disease of great importance that has led this body to develop a specific and ambitious program that aims at its eradication by the year 2050. In this article we detail some of the most interesting aspects of the epidemiology of this disease, with special attention paid to the problem of multiresistant tuberculosis, and we present up to date data on the morbidity and mortality of tuberculosis in the world.
Communicable Diseases: Achievements and Challenges for Public Health  [cached]
Schlipk?ter Ursula,Flahault Antoine
Public Health Reviews , 2010,
Abstract: The past two centuries have seen enormous achievements in control of infectious diseases, previously the leading cause of death, in large measure due to sanitation and food safety, vaccines, antibiotics and improved nutrition. This has led people to put their faith in the notion that medical science would succeed in overcoming the remaining obstacles. Vaccination has eradicated smallpox, nearly eradicated poliomyelitis and greatly reduced many other highly dangerous infections such as diphtheria, tetanus and measles. New diseases such as HIV and new forms of influenza have taken both professional and popular opinion by surprise and have renewed the challenges before the world public health community. Emergence of antibiotic-resistant strains of common organisms due to overuse of antibiotics and lack of vaccines for many dangerous microorganisms poses problems to humanity. This stresses the need for new vaccines, effective antibiotics and strengthened environmental control measures. New knowledge of the microbiological origins of cancers such as that of the cervix, stomach and liver have strengthened primary prevention and brought hope that new cures will be found for other chronic diseases of infectious origin. Tragically long delays in adopting “new” and cost effective vaccines cause hundreds of thousands of preventable deaths each year in developing and mid-level developed countries. Gains are being made in control of many tropical diseases, but malaria, tuberculosis and other infectious diseases remain enormous global problems. Research and acquisition of new knowledge, risk communication, application of currently available means and fair distribution will be great challenges to public health in the coming decades.
Marine biodiversity in Colombia: Achievements, status of knowledge, and challenges
Díaz,Juan M; Acero,Arturo;
Gayana (Concepción) , 2003, DOI: 10.4067/S0717-65382003000200011
Abstract: colombia is recognized as a megadiverse country on the basis of the number of terrestrial animal and plant species occurring within its boundaries. however, due to the circumstance that it possesses coasts on both the caribbean sea and the pacific ocean, each of them exhibiting distinct geological, oceanographic, and climatic features, colombia is perhaps the country with the highest marine biological diversity in south america and one of the most biodiverse in the new world. although scientific research concerning marine biodiversity of colombia has a very short history, considerable knowledge has been achieved in the last 10 years, particularly in regard to species inventories and ecosystem characterizations, including thematic mapping. relatively accurate estimates about the numbers of species of fishes, birds, mammals, reptiles, and some marine invertebrate groups occurring in colombian waters are now available, as well as the location, extent, and structure of the major coastal-marine ecosystems, including coral reefs, mangroves, and seagrass meadows. according to their geologic, hydrographic, climatic, and biological features, the coastal and oceanic realms of colombia have been subdivided into 18 natural ecoregions, nine in the caribbean and nine in the pacific. considering the current scientific capacity of colombia, including financial and logistic limitations, short and mid-term research plans and programs have been designed in order to orient marine biodiversity studies toward prioritary issues and geographic areas according to the responsibilities imposed by the biodiversity convention and the national biodiversity plan.
Malawi's contribution to "3 by 5": achievements and challenges
Libamba,Edwin; Makombe,Simon D; Harries,Anthony D; Schouten,Erik J; Yu,Joseph Kwong-Leung; Pasulani,Olesi; Mhango,Eustice; Aberle-Grasse,John; Hochgesang,Mindy; Limbambala,Eddie; Lungu,Douglas;
Bulletin of the World Health Organization , 2007, DOI: 10.1590/S0042-96862007000200015
Abstract: problem: many resource-poor countries have started scaling up antiretroviral therapy (art). while reports from individual clinics point to successful implementation, there is limited information about progress in government institutions at a national level. approach: malawi started national art scale-up in 2004 using a structured approach. there is a focus on one generic, fixed-dose combination treatment with stavudine, lamivudine and nevirapine. treatment is delivered free of charge to eligible patients with hiv and there is a standardized system for recruiting patients, monthly follow-up, registration, monitoring and reporting of cases and outcomes. all treatment sites receive quarterly supervision and evaluation. local setting: in january 2004, there were nine public sector facilities delivering art to an estimated 4 000 patients. by december 2005, there were 60 public sector facilities providing free art to 37 840 patients using national standardized systems. analysis of quarterly cohort treatment outcomes at 12 months showed 80% of patients were alive, 10% dead, 9% lost to follow-up and 1% had stopped treatment. lessons learned: achievements were the result of clear national art guidelines, implementing partners working together, an intensive training schedule focused on clinical officers and nurses, a structured system of accrediting facilities for art delivery, quarterly supervision and monitoring, and no stock-outs of antiretroviral drugs. the main challenges are to increase the numbers of children, pregnant women and patients with tuberculosis being started on art, and to avert high early mortality and losses to follow-up. the capacity of the health sector to cope with escalating case loads and to scale up prevention alongside treatment will determine the future success of art delivery in malawi.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.