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Search Results: 1 - 10 of 605310 matches for " Oliver Rúa "
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A Survey of Genetic Diversity of the Weedy Species Ipomoea lacunosa L. in the USA Mid-South  [PDF]
Nilda R. Burgos, Daniel O. Stephenson, Hesham A. Agrama, Lawrence R. Oliver, Jason A. Bond
American Journal of Plant Sciences (AJPS) , 2011, DOI: 10.4236/ajps.2011.23045
Abstract: Morningglories (Ipomoea spp.) are among the most troublesome weedy species in agroecological environments. Ipomoea lacunosa is one of the most prevalent of these species. Localized adaptations resulted in the evolution of several I. lacunosa ecotypes in North America, which could potentially impact its response to crop management practices. To evaluate the genetic diversity and population structure of I. lacunosa populations, we amplified inter-simple sequence repeats loci by polymerase chain reaction (ISSR-PCR) of 64 accessions using 14 ISSR primers for Ipomoea. Of these, 64 polymorphic fragments were scored. Analysis of Nei’s genetic distance (GD) values placed the accessions into four genotypic clusters, two of which were composed primarily of accessions from Arkansas and Mississippi with GD between clusters of 0.318. The overall GD was 0.238, indicating a narrow genetic base. Population structure analysis determined three ancestral subgroups, with the majority of Arkansas and Mississippi accessions separated into two subgroups. The existence of various genotypes and ecotypes of I. lacunosa demonstrates the evolutionary diversification of this weedy species as it adapts to new colonized environments and agricultural activities.
Prevalence of intestinal parasitosis in scholar children in a district of the Peruvian highland
Oliver Rúa,Giuliana Romero,Franco Romaní
Revista Peruana de Epidemiologia , 2010,
Abstract: Objective: To asses the prevalence of intestinal parasitic infections among students of elemental school in Llama district and describe the possible association with the most important sociodemographical and family characteristics. Methods: Two faecal samples were collected from 88 of children from 1 to 4 study year in an elementary school of Llama district, Cajamarca, Peru, following informed consent from their legal guardians. Parasitological diagnostic was made using spontaneous sedimentation method and the conventional Graham′s test. Results: Global prevalence of intestinal parasitosis was high (80.7%). The parasites most frequently found were: Blastocistis hominis (61.4%), Entamoeba coli (30.7%), Giardia lamblia (9.1%), Endolimax nana (5.7%), Hymenolepis nana (3.4%), Iodamoeba bütschlii (13.6%), Enterobius vermicularis (3.4%), Ascaris lumbricoides (1.1%) and Chilomastix mesnilii (1.1%). There was a significant association between previous 3 months treatment time and lower parasitoses (p< 0.05). Conclusions: There is a high prevalence of intestinal parasitosis in children in an elementary school of Llama district. No pathogen protozoos were the most frequent. This is the first study in this community. Programs of sanitary improvement and environmental education of coproparasites should be improved and implemented in this region of Peru.
Numerical Simulations of Magnetoacoustic-Gravity Waves in the Solar Atmosphere
K. Murawski,A. K. Srivastava,J. A. McLaughlin,R. Oliver
Physics , 2012, DOI: 10.1007/s11207-012-0202-7
Abstract: We investigate the excitation of magnetoacoustic-gravity waves generated from localized pulses in the gas pressure as well as in vertical component of velocity. These pulses are initially launched at the top of the solar photosphere that is permeated by a weak magnetic field. We investigate three different configurations of the background magnetic field lines: horizontal, vertical and oblique to the gravitational force. We numerically model magnetoacoustic-gravity waves by implementing a realistic (VAL-C) model of solar temperature. We solve two-dimensional ideal magnetohydrodynamic equations numerically with the use of the FLASH code to simulate the dynamics of the lower solar atmosphere. The initial pulses result in shocks at higher altitudes. Our numerical simulations reveal that a small-amplitude initial pulse can produce magnetoacoustic-gravity waves, which are later reflected from the transition region due to the large temperature gradient. The atmospheric cavities in the lower solar atmosphere are found to be the ideal places that may act as a resonator for various oscillations, including their trapping and leakage into the higher atmosphere. Our numerical simulations successfully model the excitation of such wave modes, their reflection and trapping, as well as the associated plasma dynamics.
Binding of Host Factors Influences Internalization and Intracellular Trafficking of Streptococcus uberis in Bovine Mammary Epithelial Cells
Raul A. Almeida,John R. Dunlap,Stephen P. Oliver
Veterinary Medicine International , 2010, DOI: 10.4061/2010/319192
Abstract: We showed that internalization of Streptococcus uberis into bovine mammary epithelial cells occurred through receptor- (RME) and caveolae-mediated endocytosis (CME). We reported also that treatment of S. uberis with host proteins including lactoferrin (LF) enhanced its internalization into host cells. Since the underlying mechanism(s) involved in such enhancement was unknown we investigated if preincubation of S. uberis with host proteins drives internalization of this pathogen into host cells through CME. Thus, experiments involving coculture of collagen-, fibronectin-, and LF-pretreated S. uberis with bovine mammary epithelial cells treated with RME and CME inhibitors were conducted. Results showed that internalization of host proteins-pretreated S. uberis into mammary epithelial cells treated with RME inhibitors was higher than that of untreated controls. These results suggest that pretreatment with selected host proteins commits S. uberis to CME, thus avoiding intracellular bactericidal mechanisms and allowing its persistence into bovine mammary epithelial cells. 1. Introduction To survive in well-protected host microenvironments, bacterial pathogens have evolved pathogenic strategies aimed to bypass host defenses mechanisms. Adherence to and internalization into host cells are bacterial-induced strategies that allow bacterial pathogens to defeat defense mechanisms functional at mucosal surfaces. However, after internalization, pathogens need to overcome intracellular bacteriostatic/bactericidal mechanisms, such as endosome acidification and endosome-lysosome fusion. Classical and nonclassical intracellular bacterial pathogens have evolved strategies to circumvent and even take advantage of bactericidal mechanisms operating in the host cell cytoplasm. Hence, while some pathogens enter host cells via receptor-mediated endocytosis (RME) and exploit acidic endosomal pH to fully express their virulence factors [1, 2], other pathogens exploit caveolae mediated endocytosis (CME), which is not linked to endosomal acidification or fusion with the lysosome [3–8]. Exploitation of CME to gain access into the host cell has been described for a growing list of pathogens, including S. uberis [9]. Binding of host proteins such as extracellular matrix proteins has been associated with enhanced adherence to and internalization into host cells by several pathogens. The mechanism by which adherence and internalization are enhanced seems to occur through a molecular bridge (or sandwich) formed by the pathogen, the host protein, and its corresponding receptor located on
The Impact of Nature Experience on Willingness to Support Conservation
Patricia A. Zaradic, Oliver R. W. Pergams, Peter Kareiva
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0007367
Abstract: We hypothesized that willingness to financially support conservation depends on one's experience with nature. In order to test this hypothesis, we used a novel time-lagged correlation analysis to look at times series data concerning nature participation, and evaluate its relationship with future conservation support (measured as contributions to conservation NGOs). Our results suggest that the type and timing of nature experience may determine future conservation investment. Time spent hiking or backpacking is correlated with increased conservation contributions 11–12 years later. On the other hand, contributions are negatively correlated with past time spent on activities such as public lands visitation or fishing. Our results suggest that each hiker or backpacker translates to $200–$300 annually in future NGO contributions. We project that the recent decline in popularity of hiking and backpacking will negatively impact conservation NGO contributions from approximately 2010–2011 through at least 2018.
Recruitment rates and reasons for community physicians' non-participation in an interdisciplinary intervention study on leg ulceration
Oliver R Herber, Wilfried Schnepp, Monika A Rieger
BMC Medical Research Methodology , 2009, DOI: 10.1186/1471-2288-9-61
Abstract: The first recruitment phase stressed the recruitment of GPs, the second the recruitment of specialists. Throughout the recruitment process data were collected through phone conversations with GP practices who indicated reasons for non-participation.Despite great efforts to recruit physicians, the recruitment rate reached only 26 out of 1549 contacted practices (1.7%) and 12 out of 273 (4.4%) practices during the first and second recruitment phase respectively. The overall recruitment rate over the 16-month recruitment period was 2%. With a target recruitment rate of n = 300, only 45 patients were enrolled in the study, not meeting study projections. Various reasons for community physicians' non-participation are presented as stated spontaneously during phone conversations that might explain low recruitment rates. The recruitment strategy utilised is discussed against the background of factors associated with high participation rates from the international literature.Time, money, and effort needed during the planning and recruitment phase of a study must not be underestimated to avoid higher than usual rates of refusal and lack of initial contact. Pilot studies prior to a study start-up may provide some evidence on whether the target recruitment rate is feasible.Current Controlled Trials ISRCTN42122226.Unlike the UK, for instance, where common leg ulcers are diagnosed, treated, and followed up in nurse-run leg ulcer clinics, in Germany these patients are solely in the hands of physicians. Traditionally, the German health care system has no gatekeeping functions; instead patients are free to select a doctor of their choice (GP or specialist) who is located in the community. Since there is no mechanism to control this "self-selected" gatekeeping, patients frequently choose specialists directly. There are only a few incentives for patients to first contact a GP in Germany; none of them apply to leg ulcer patients. For German GPs it is financially rather unattractive to
A systematic review on the impact of leg ulceration on patients' quality of life
Oliver R Herber, Wilfried Schnepp, Monika A Rieger
Health and Quality of Life Outcomes , 2007, DOI: 10.1186/1477-7525-5-44
Abstract: Original articles published in English and German between 1990 and 2006 were included if the findings were analysed at the level of patients. Articles were excluded if (1) they investigated the impact of specific treatments or settings on QoL or (2) focused mainly on arterial ulcers or diabetic foot ulcers.Twenty-four original research articles met the inclusion criteria; 11 studies used a quantitative, 11 studies a qualitative, and 2 used a mixed method approach. The findings were collapsed into 5 core domains. Quantitative studies commonly investigated the parameters of pain, sleep, social isolation, and physical mobility. Patients had significantly more pain, more restrictions regarding social functioning, less vitality, and limitations with respect to emotional roles compared to the respective controls. Other problem areas identified were restrictions in work capacity, recreation, social interaction, psychological well-being, as well as problems caused by treatment regimes. Inconclusive results were obtained regarding pain intensity, physical restrictions, and gender effects.Numerous original studies neither undertook a differentiation of participants by ulcer aetiology nor did they analyse the results according to gender differences.As leg ulceration has an impact on QoL, national guidelines on the treatment of leg ulceration need to more specifically address these far-ranging effects identified in this review.The care of patients with chronic diseases is the focus of many researchers from different academic disciplines. One question they try to answer is how health professionals can improve the life and well-being of chronically ill patients. In a co-operative research project between the medical and nursing profession we developed a nurse-led education programme that aims to enhance self-care agency in leg ulcer patients. One of the primary outcome measures of the intervention in that multi-site clinical trail (ISRCTN42122226) is the assessment of quality of
A. Wainwright,L. Edvinsson,K.R. Oliver
The Scientific World Journal , 2001, DOI: 10.1100/tsw.2001.445
Site-dependent magnetism of Ni adatoms on MgO/Ag(001)
Oliver R. Albertini,Amy Y. Liu,Barbara A. Jones
Physics , 2015, DOI: 10.1103/PhysRevB.91.214423
Abstract: We examine the adsorption of a single Ni atom on a monolayer of MgO on a Ag substrate using DFT and DFT+U computational approaches. We find that the electronic and magnetic properties vary considerably across the three binding sites of the surface. Two of the binding sites are competitive in energy, and the preferred site depends on the strength of the on-site Coulomb interaction U. These results can be understood in terms of the competition between bonding and magnetism for surface adsorbed transition metal atoms. Comparisons are made with a recent experimental and theoretical study of Co on MgO/Ag, and implications for scanning tunneling microscopy experiments on the Ni system are discussed.
Diagnostic Performance and Inter-Observer Agreement of 4-Dimensional Computed Tomography Parathyroid Scans in Patients with Primary and Secondary Hyperparathyroidism  [PDF]
Bundhit Tantiwongkosi, Frank R. Miller, Viet D. Nguyen, Kathleen E. Hands, Boyce B. Oliver, Alfredo A. Santillan, Wilson B. Altmeyer, Achint K. Singh, Fang Yu
Open Journal of Radiology (OJRad) , 2019, DOI: 10.4236/ojrad.2019.91008
Abstract: Background: 4D-CT has been used to localize the parathyroid adenomas and hyperplasia since 2006 as a second line study after TC-99 m MIBI and ultrasonography. However, multiple studies have shown that 4D-CT is a robust imaging method with high diagnostic accuracy, becoming increasingly popular among surgeons and radiologists. Purpose: To assess the diagnostic performance of 4D-CT scans to identify the pathologic gland(s), using pathology and intraoperative findings as gold standards. Methods: We analyzed patients with primary and secondary hyperparathyroidism who had intraoperative reports, pathology, parathyroid hormone levels, and preoperative 4D-CT. Histology, surgical findings, and decreased parathyroid hormone levels were used as gold standards. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy and 95% confidence interval were calculated. Fleiss’ kappa was used to assess the inter-observer agreement. Results: Sixty-seven patients were included. Sixty-two patients had a single adenoma, and five patients had a multiple gland disease (adenomas or hyperplasia). A total of 72 glands were proven to have parathyroid adenomas or hyperplasia. The sensitivity, specificity, PPV, NPV and accuracy are 85%, 97%, 96%, 87% and 91% for lateralization and 76%, 96%, 85%, 92% and 90% for quadrant localization, respectively in single-gland disease. The sensitivity, specificity, PPV, NPV and accuracy are 88%, 100%, 100%, 50% and 90% for lateralization and 71%, 100%, 100%, 60% and 80% for quadrant localization respectively in multiple-gland disease. Fleiss’ kappa value is 5.6 (moderate inter-observer agreement). Conclusion: 4D-CT is a robust method in the localization of hyperfunctioning parathyroid glands with high accuracy and at least moderate inter-observer agreement.
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