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At least 631 records · Page 35Linked to original sources

PubMed1998

A microsatellite-based multilocus phylogeny of the Drosophila melanogaster species complex.

Uncovering the genealogy of closely related species remains a major challenge for phylogenetic reconstruction. It is unlikely that the phylogeny of a single gene will represent the phylogeny of a species as a whole [1], but DNA sequence data across a large number of loci can be combined in order to obtain a consensus tree [2]. Long sequences are needed, however, to minimize the effect of (infrequent) base substitutions, and sufficient individuals must be sequenced per species to account for intraspecific polymorphisms, an overwhelming task using current DNA sequencing technology. By contrast, microsatellites are easy to type [3], allowing the analysis of many loci in multiple individuals. Despite their successful use in mapping [4,5], behavioural ecology [6] and population genetics [7], their usefulness for the phylogenetic reconstruction of closely related taxa has never been demonstrated, even though microsatellites are often conserved across species [8-10]. One drawback to microsatellite use is their high mutation rate (10(-4)-10(-2)), combined with an incomplete understanding of their mutation patterns. Many microsatellites are available for Drosophila melanogaster, and they are distributed throughout the genome [11]. Most can be amplified in the D. melanogaster species complex [12,13] and have low mutation rates [14, 15]. We show that microsatellite-specific distance measurements [16] correlate with other multilocus distances, such as those obtained from DNA-DNA hybridization data. Thus microsatellites may provide an ideal tool for building multilocus phylogenies. Our phylogenetic reconstruction of the D. melanogaster complex provides strong evidence that D. sechellia arose first, followed by a split between D. simulans and D. mauritiana.

Animals↗

PubMed1998

Latex allergy.

Natural latex from the rubber tree Hevea brasiliensis is an allergen in persons with significant cumulative latex exposure, such as those in the health care and rubber industries, as well as those undergoing repeated surgeries, especially if they undergo surgeries early in life. Symptoms of latex allergy may progress rapidly and unpredictably to anaphylaxis. The prevalence of latex allergy has increased as the use of rubber gloves in health care settings has increased. Airborne latex particles that adhere to the cornstarch used to powder gloves are a significant cause of respiratory symptoms and a source of sensitization. Once an individual has become sensitized, he or she may experience allergic symptoms when exposed to any product containing latex. Diagnosis is made initially by the history. Latex-specific IgE testing and skin prick testing may confirm the suspicion. The most effective strategy in the treatment of latex allergy is avoidance; however, there is a large group of sensitized people who have not been identified and who do not recognize that their symptoms are caused by latex allergy. Physicians caring for latex-sensitive persons must act as their advocates in building awareness of the problem and developing protocols for their safe care. Latex-sensitized persons should be educated about the latex content of common objects.

Adult↗

PubMed2001

Learning to solve planning problems efficiently by means of genetic programming.

Declarative problem solving, such as planning, poses interesting challenges for Genetic Programming (GP). There have been recent attempts to apply GP to planning that fit two approaches: (a) using GP to search in plan space or (b) to evolve a planner. In this article, we propose to evolve only the heuristics to make a particular planner more efficient. This approach is more feasible than (b) because it does not have to build a planner from scratch but can take advantage of already existing planning systems. It is also more efficient than (a) because once the heuristics have been evolved, they can be used to solve a whole class of different planning problems in a planning domain, instead of running GP for every new planning problem. Empirical results show that our approach (EvoCK) is able to evolve heuristics in two planning domains (the blocks world and the logistics domain) that improve PRODIGY4.0 performance. Additionally, we experiment with a new genetic operator --Instance-Based Crossover--that is able to use traces of the base planner as raw genetic material to be injected into the evolving population.

Algorithms↗

PubMed2003

Building syntactic structures in speaking: a bilingual exploration.

In a series of three experiments we investigated syntactic priming using a sentence recall task. Participants read and memorized a target sentence for later recall. After reading a prime sentence and engaging in a distraction task, they were asked to produce the target sentence aloud. Earlier investigations have shown that this task is sensitive to a syntactic priming effect. That is, the syntactic form of the prime sentence sometimes influences the syntactic form of the recalled target. In this paper we report on a variation on this task, using Spanish-English bilingual participants. In the first two experiments we replicated the prepositional phrase priming effect using English target sentences and Spanish prime sentences. In the final experiment we investigated two additional syntactic forms, using Spanish target sentences and English prime sentences. Implications for models of syntax generation and bilingual speech production are discussed.

Humans↗

PubMed2006

[Ecological factors linked to the presence of Aedes aegypti larvae in highly infested areas of Playa, a municipality belonging to Ciudad de La Habana, Cuba].

OBJECTIVES: To identify local ecological factors that might have had an impact on the higher infestation rates by the vector mosquito Aedes aegypti seen in four urban health districts of Ciudad de La Habana, Cuba, and to determine the type of containers with the highest number of larvae. METHODS: This is a descriptive study that was carried out in four health areas (Docente, 28 de Enero, 26 de Julio, and 1. degrees de Enero) within Playa, a municipality belonging to Ciudad de La Habana, Cuba. These areas were chosen because of the persistent presence of the dengue vector throughout 2003. All buildings on the selected blocks were inspected between April 2004 and March 2005, and note was taken of existing water deposits (type, number, and location) and of surrounding ecological factors (existence of a patio and shade, the way tanks were covered, the presence of organic matter inside them, and the overall cleanliness of the dwelling). Using filtration, the mosquito larvae and pupae in each deposit were counted. Pupae were typified as to their taxonomic species under a stereoscopic microscope. RESULTS: The types of deposits where larvae and pupae of A. aegypti were most often found in all areas were low tanks and small artificial containers. In three of the study areas the greatest numbers of pupae were found in low tanks (88.6%, 100%, and 56.6%), 90.9% of which were uncovered or only partially covered. On the other hand, in the fourth study area small artificial deposits were the most commonly infested (85.7%). A correlation was noted between the number of deposits in infested houses and the presence of a patio (chi(2) = 29.59; P = 0.0001), partial shade (chi(2) = 4.108; P = 0.0001), shrubbery (chi(2) = 43.59; P = 0.0001) and trees (chi(2) = 101.459; P = 0.0001), as well as poor hygiene (chi(2) = 53.76; P = 0.0001). CONCLUSIONS: Artificial deposits, especially low tanks and small containers, are the most frequent breeding sites for A. aegypti and are therefore risk factors for infestation with this vector species. Uncovered tanks containing organic matter and located in the shade on the outside of homes were found to present the highest risk in this respect.

Aedes↗

PubMed2006

[Classification method of deciduous-conifer mixed forest in jilin province based on GIS-TM remote sensing image].

To improve the accuracy of automatic classification and identification of TM remote sensing images in forest area, an expert system for automatically classifying and identifying deciduous-conifer mixed forest was built up, based on the GIS technique, quantitative analysis on the internal relations between geographic factors such as DEM and slope aspect and environment factors like soil type, and qualitative analysis on the spectrum information and preclassification information of sensing images, aimed to build a classification knowledge system. Taking the TM remote sensing image of Wangqing Forest Bureau in Jilin Province as an example, the study showed that this expert system could obviously reduce the influence of mixed pixel and terrain shadow. The classification precision of this system was increased by 14.22%, compared with that of Iterative Self-Organizing Data Analysis Techniques Algorithm (ISODATA) unsupervised classification, and the Kappa index was 0.7556, which could help to classify needle, deciduous and mixed forests. Introducing GIS data into the expert system could also solve the problem that TM remote sensing image could not do, due to the loss of correct spectrum value in cloudy and shady area.

China↗

PubMed1994

Modification of lignin biosynthesis in transgenic Nicotiana through expression of an antisense O-methyltransferase gene from Populus.

An aspen lignin-specific O-methyltransferase (bi-OMT; S-adenosyl-L-methionine: caffeic acid/5-hydroxyferulic acid 3/5-O-methyltransferase, EC 2.1.1.68) antisense sequence in the form of a synthetic gene containing the cauliflower mosaic virus 35S gene sequences for enhancer elements, promoter and terminator was stably integrated into the tobacco genome and inherited in transgenic plants with a normal phenotype. Leaves and stems of the transgenes expressed the antisense RNA and the endogenous tobacco bi-OMT mRNA was suppressed in the stems. Bi-OMT activity of stems was decreased by an average of 29% in the four transgenic plants analyzed. Chemical analysis of woody tissue of stems for lignin building units indicated a reduced content of syringyl units in most of the transgenic plants, which corresponds well with the reduced activity of bi-OMT. Transgenic plants with a suppressed level of syringyl units and a level of guaiacyl units similar to control plants were presumed to have lignins of distinctly different structure than control plants. We concluded that regulation of the level of bi-OMT expression by an antisense mechanism could be a useful tool for genetically engineering plants with modified lignin without altering normal growth and development.

Base Sequence↗

PubMed2006

[Evaluation of sandfly control in Lobato municipality, Paraná State, southern Brazil].

Sandfly control measures were evaluated at the Da Barra Ranch, Lobato municipality, Paraná State, Brazil. The insects were captured with Falcão traps in houses, a cattle corral, and a forest area from July to November 1999 and from February to June 2000. In December 1999 and January 2000 the following measures were taken to decrease the sandfly density in peridomiciliary areas and domiciles: (i) screens were placed on windows of buildings (domiciles, dormitory, cafeteria); (ii) all organic material was cleaned from the peridomiciliary area; and (iii) buildings were sprayed for insects. There were more Nyssomyia whitmani, Pintomyia fischeri, P. monticola, and Brumptomyia brumpti specimens in the former period, while N. neivai, Migonemyia migonei, and N. pessoai predominated in the latter. In the initial period most of the sandflies were captured in the forest and in the latter period in the houses. The sandfly control measures did not reduce the sandfly population on the Da Barra Ranch, but they led to significant proportional changes in the insect fauna composition.

Animals↗

PubMed2006

Saving costs using an ounce of prevention: introduction of a regional stroke prevention clinic.

Trillium Health Centre (THC) is one of Canada's largest community hospitals and a regional provider of tertiary-level cardiac, neuroscience, and orthopedic care. In 2001, it was named one of nine Regional Stroke Centres in Ontario, with a mandate to coordinate stroke services across the continuum of care in keeping with best practices in the west Greater Toronto Area (GTA). Within its role as a Regional Stroke Centre, THC has successfully implemented an innovative approach to the delivery of stroke prevention services in its regional catchment area. Building on best practices, it has introduced a specialized and interdisciplinary team to provide timely and effective primary and secondary prevention services. The rapid growth in utilization to more than 2000 patients in the last fiscal year (2004-2005), suggests that the clinic is meeting a real need in the community for stroke prevention services. Many of these patients now benefit from appropriate medical management, stroke awareness education, lifestyle counselling, and expedited referrals to other specialists. The Regional Stroke Prevention Clinic (RSPC) may be the first step in preventing a stroke, thus avoiding the social costs to people with strokes and their families, and the financial burden on the health care system.

Benchmarking↗

PubMedDate not supplied

Identifying the characteristic secondary ions of lignin polymer using ToF-SIMS.

The chemical structure of lignin, a complex, irregular polymer of phenylpropane units that occurs in plant cell walls, was investigated using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The positive ToF-SIMS spectra of lignin isolated from pine and beech wood showed prominent secondary ions possessing guaiacyl (at m/z 137 and 151) or syringyl (at m/z 167 and 181) rings, which are the basic building units of lignin polymer. This shows that ToF-SIMS is a useful tool for lignin structural analysis. The peaks at m/z 137 and 167 were assigned as the C6-C1 ion, and the peaks at m/z 151 and 181 may be double-component, the C6-C1 ion and the C6-C2 ion. We confirmed the characteristic guaiacyl ions using a synthetic lignin model compound, dehydrogenation polymer (DHP), which was formed by polymerizing of unlabeled and deuterium-labeled coniferyl alcohols. The formation mechanism of the main secondary ions was deduced by labeling specific positions of coniferyl alcohols with a stable isotope to study the relationship between chemical structure and secondary ion formation in ToF-SIMS.

Deuterium↗

PubMed2002

Assuring the safety of genetically modified (GM) foods: the importance of an holistic, integrative approach.

Genes change continuously by natural mutation and recombination enabling man to select and breed crops having the most desirable traits such as yield or flavour. Genetic modification (GM) is a recent development which allows specific genes to be identified, isolated, copied and inserted into other plants with a high level of specificity. The food safety considerations for GM crops are basically the same as those arising from conventionally bred crops, very few of which have been subject to any testing yet are generally regarded as being safe to eat. In contrast a rigorous safety testing paradigm has been developed for GM crops, which utilises a systematic, stepwise and holistic approach. The resultant science based process, focuses on a classical evaluation of the toxic potential of the introduced novel trait and the wholesomeness of the transformed crop. In addition, detailed consideration is given to the history and safe use of the parent crop as well as that of the gene donor. The overall safety evaluation is conducted under the concept known as substantial equivalence which is enshrined in all international crop biotechnology guidelines. This provides the framework for a comparative approach to identify the similarities and differences between the GM product and its comparator which has a known history of safe use. By building a detailed profile on each step in the transformation process, from parent to new crop, and by thoroughly evaluating the significance from a safety perspective, of any differences that may be detected, a very comprehensive matrix of information is constructed which enables the conclusion as to whether the GM crop, derived food or feed is as safe as its traditional counterpart. Using this approach in the evaluation of more than 50 GM crops which have been approved worldwide, the conclusion has been that foods and feeds derived from genetically modified crops are as safe and nutritious as those derived from traditional crops. The lack of any adverse effects resulting from the production and consumption of GM crops grown on more than 300 million cumulative acres over the last 5 years supports these safety conclusions.

Algorithms↗

PubMed2001

[Risk management in the hospital milieu: needs and implications].

Medicine can be dangerous for the patients, the caregivers, the visitors and the environment. Technological progress provides devices and drugs that are always more powerful, more efficacious, but at the same time able to lead to severe side effects. This paper describes the system set up in a university hospital to fulfill legal requirements. Specialists in specific fields build up commissions, which are united in a coordination office. A general policy for the hospital has been decided, but each commission is responsible for managing the risks in its field. The overall philosophy moved from a quality assurance to a quality management system, in which the employee involved in an incident or an accident is no longer considered the only culprit except in cases of obvious violation of established procedures. In order to be efficient, the system must be as simple as possible, and well known, so that collaborators gain confidence in it. Once this cultural revolution is accomplished, quality but also security of the procedures will be improved. Its impact on cost is more questionable, as the system generates running costs which might be higher than the savings it might bring.

Algorithms↗

PubMed2006

Building bridges across differences to meet social action goals: being and creating allies among People of Color.

Although challenges of anti-racist work are most commonly framed in relation to White people and People of Color, there are significant challenges involved in creating allies across minority racial groups. This article describes our experiences within a community organization aimed at training anti-racist culturally sensitive K-12 educators. As Asian American and Native American facilitators within a group of facilitators of color who were predominantly Black, we describe our experiences of relative marginalization and our (mostly failed) attempts to create change within the organization to be more inclusive of the perspectives, experiences, and needs of non-Black people/students of color. We contextualize these experienced conflicts in relation to race hierarchies, the "divide and conquer strategy" and the maintenance of White privilege. We offer reflections for how racial minorities engaged in anti-racist education could be better allies and how organizations might better foster environments that contribute to the creation of these alliances.

Community Networks↗

PubMed1998

Conceptual development of an information systems framework for improving continuity in epidemiological research.

Lack of continuity is a problem for survey-based epidemiological research. Poor access to experience and inadequate retention of information means new projects seldom build on successful predecessors to the maximum possible extent. We have designed a data management framework which addresses this problem using a well-known information systems approach. Our ideas provide a means of storing data in a manner which reflects the original research concepts. This makes collected data accessible and understandable without reference to the questionnaire, and allows new questionnaires to be designed quickly and easily. Our framework provides a means for recording developmental, conceptual and other supporting information and documentation which is traditionally poorly conserved. We illustrate the components of the framework using a major Australian epidemiological project as a case study. Once the necessary software is developed, our framework will improve organisational memory within individual research units and has the potential to become a valuable support tool for survey-based research.

Australia↗

PubMed2004

Gene mining: a novel and powerful ensemble decision approach to hunting for disease genes using microarray expression profiling.

Current applications of microarrays focus on precise classification or discovery of biological types, for example tumor versus normal phenotypes in cancer research. Several challenging scientific tasks in the post-genomic epoch, like hunting for the genes underlying complex diseases from genome-wide gene expression profiles and thereby building the corresponding gene networks, are largely overlooked because of the lack of an efficient analysis approach. We have thus developed an innovative ensemble decision approach, which can efficiently perform multiple gene mining tasks. An application of this approach to analyze two publicly available data sets (colon data and leukemia data) identified 20 highly significant colon cancer genes and 23 highly significant molecular signatures for refining the acute leukemia phenotype, most of which have been verified either by biological experiments or by alternative analysis approaches. Furthermore, the globally optimal gene subsets identified by the novel approach have so far achieved the highest accuracy for classification of colon cancer tissue types. Establishment of this analysis strategy has offered the promise of advancing microarray technology as a means of deciphering the involved genetic complexities of complex diseases.

Acute Disease↗

PubMed2004

A decision chart for assessing and improving the transferability of economic evaluation results between countries.

OBJECTIVE: To develop a user-friendly tool for managing the transfer of economic evaluation results. METHODS: Factors that may influence the transfer of health economic study results were systematically identified and the way they impact on transferability was investigated. A transferability decision chart was developed that includes: knock-out criteria; a checklist based on the transferability factors; and methods for improving transferability and for assessing the uncertainty of transferred results. This approach was tested on various international cost-effectiveness studies in the areas of interventional cardiology, vaccination and screening. RESULTS: The transfer of study results is possible pending the outcomes of the transferability check and necessary adjustments. Transferability factors can be grouped into areas of methodological, healthcare system and population characteristics. Different levels of effort are required for analysis of factors, ranging from very low (e.g. discount rate) to very high (e.g. practice variation). The impact of differences of most transferability factors can be estimated via the key health economic determinants: capacity utilisation, effectiveness, productivity loss and returns to scale. Depending on the outcomes of the transferability check a correction of the study results for inflation and for differences related to currencies or purchasing power might be sufficient. Otherwise, modelling-based adjustments might be necessary, requiring the (re-)building and sometimes structural modification of the study model. For determination of the most essential adjustments, a univariate sensitivity analysis seems appropriate. If not all relevant study parameters can be substituted with country-specific ones, multivariate or probabilistic sensitivity analysis seems to be a promising way to quantify the uncertainty associated with a transfer. If study results cannot be transferred, the transfer of study models or designs should be investigated as this can significantly save time when conducting a new study. CONCLUSIONS: Our transferability decision chart is a transparent and user-friendly tool for assessing and improving the transferability of economic evaluation results. A state of the art description of the methodology in a study, providing detailed components for calculation, is not only essential for determining its transferability but also for improving it via modelling adjustments.

Cost-Benefit Analysis↗

PubMed1993

Measurements of year-long exposure to tree nursery workers using multiple pesticides.

A year-long nurseryworker pesticide exposure study was designed to measure and evaluate the exposure occurring to workers who had the potential for simultaneous exposure to multiple pesticides. This four-State study was conducted in five nurseries (four USDA Forest Service and one State) involved in conifer seedling production. Primary comparisons were made among nursery workers in the Pacific northwest and south central United States. Worker exposure was assessed by using patches attached to clothing, handrinse samples and urine excreted from potentially exposed workers. In addition, dislodgeable residue in rinsate from a water wash of pesticide-treated seedlings was also evaluated. Four different groups of field workers, designated as applicators, weeders, scouts and packers, were included. The pesticide absorbed dose, assessed by urine analysis of pesticide metabolites and the deposition of pesticide on patches attached to the clothing of field workers, was monitored as they performed their duties under normal conditions (e.g., typical clothing, pesticide application). Monitoring was performed for the 14 different pesticides which were used in these nurseries. Seven pesticides were studied in more detail using biological monitoring. For these compounds, metabolites known to be excreted in the urine of exposed humans or other mammals were used to estimate the dose of pesticide absorbed by the exposed workers. The highest percentage of positive samples came from dislodgeable residue samples (8.3%) followed by patch samples (3.2%), handrinse (2.9%), and urine samples (1.3%). To summarize the conclusions from the urinary excretion data, 12 of the 73 nursery workers in the study received a low absorbed dose of pesticide. Biological monitoring revealed that three pesticides (benomyl, bifenox and carbaryl) were found in the urine of some of the workers. Of the 3,134 urine samples analyzed there were 42 positive; 11 urine samples were positive for benomyl, while bifenox was responsible for 13 positives and carbaryl accounted for the remaining 18. The 12-week continuous monitoring of urine showed that metabolites of these materials were rapidly excreted; thus, no build-up in the body is anticipated. Margins of Safety (MOS) calculations were made to provide an assessment of the significance of the exposure. Based on the low frequency of positive urine samples in the study, the low levels of metabolites when they were found, their apparent rapid excretion rate and the No Observed Effect Level (NOEL) data, furnished from other sources, nursery worker exposure to pesticides in these conifer nurseries is below health threatening levels.

Adult↗

PubMedDate not supplied

Interrupting Chagas disease transmission in Venezuela.

The interruption of vectorial transmission of Chagas disease in Venezuela is attributed to the combined effects of ongoing entomoepidemiological surveillance, ongoing house spraying with residual insecticides and the concurrent building and modification of rural houses in endemic areas during almost five decades. The original endemic areas which totaled 750,000 km(2), have been reduced to 365,000 km(2). During 1958-1968, initial entomological evaluations carried out showed that the house infestation index ranged between 60-80%, the house infection index at 8-11% and a house density index of 30-50 triatomine bugs per house. By 1990-98, these indexes were further reduced to 1.6-4.0%, 0.01-0.6% and 3-4 bugs per house respectively. The overall rural population seroprevalence has declined from 44.5% (95% C.I.: 43.4-45.3%) to 9.2% (95% C.I.: 9.0-9.4%) for successive grouped periods from 1958 to 1998. The annual blood donor prevalence is firmly established below 1%. The population at risk of infection has been estimated to be less than four million. Given that prevalence rates are stable and appropriate for public health programmes, consideration has been given to potential biases that may distort results such as: a) geographical differences in illness or longevity of patients; b) variations in levels of ascertainment; c) variations in diagnostic criteria; and d) variations in population structure, mainly due to appreciable population migration. The endemic areas with continuous transmission are now mainly confined to piedmonts, as well as patchy foci in higher mountainous ranges, where the exclusive vector is Rhodnius prolixus. There is also an unstable area, of which landscapes are made up of grasslands with scattered broad-leaved evergreen trees and costal plains, where transmission is very low and occasional outbreaks are reported.

Adolescent↗