4,071 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
High diagnostic yield of tuberculosis from screening urine samples from HIV-infected patients with advanced immunodeficiency using the Xpert MTB/RIF assay.
No full text: ABSTRACT:: We determined the diagnostic yield of the Xpert MTB/RIF assay for tuberculosis (TB) when testing small volumes of urine from ambulatory HIV-infected patients prior to starting antiretroviral therapy (ART) in South Africa. Compared to a gold standard of sputum culture, the sensitivity of urine Xpert among those with CD4 cell counts of <50, 50-100 and >100 cells/?L were 44.4%, 25.0% and 2.7% (P=0.001), respectively. Urine Xpert testing provides a means of rapid TB diagnosis in patients with advanced immunodeficiency and poor prognosis. These data are indicative of high rates of TB dissemination and renal involvement in this clinical population
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Andrew D. White Professors-At-Large lectures.
No full textRecorded in Ithaca, NY by Cornell University., Sponsored by: Andrew D. White Professors-At-Large Program., Speaker(s): Well-known author., Reading, March 27, 1985.43 minutesWelty reads her short story, The Wide Net.1_1b7n8g9v1_hknzm40
The Life of the Author: D. H. Lawrence
No full textThe Life of the Author: D. H. Lawrence is a focused exploration of the whole of the author’s life and writing career. Combining biographical detail and close readings of works in different genres, the book illuminates the complexities of Lawrence’s writing through a careful, questioning approach to biographical sources and recent scholarship. Andrew Harrison provides original insights into Lawrence’s relationship to working-class experience, his anti-suffragist feminist views, his reaction to the Great War, his responses to racial and cultural difference, his attitudes towards sex, sexuality, and sexual identity, and much more
Mechanics of elastic networks
No full textWe consider a periodic lattice structure in d=2 or 3 dimensions with unit cell comprising Z thin elastic members emanating from a similarly situated central node. A general theoretical approach provides an algebraic formula for the effective elasticity of such frameworks. The method yields the effective cubic elastic constants for three-dimensional space-filling lattices with Z=4, 6, 8, 12 and 14, the last being the ‘stiffest’ lattice proposed by Gurtner & Durand (Gurtner & Durand 2014 Proc. R. Soc. A 470, 20130611. (doi:10.1098/rspa.2013.0611)). The analytical expressions provide explicit formulae for the effective properties of pentamode materials, both isotropic and anisotropic, obtained from the general formulation in the stretch-dominated limit for Z=d+1.Peer reviewe
High sensitivity of ultrasound for the diagnosis of tuberculosis in adults in South Africa: A proof-of-concept study.
No full textBACKGROUND: There are limited data on the performance characteristics of ultrasound for the diagnosis of pulmonary tuberculosis in both HIV-positive and HIV-negative persons. The objective of this proof-of-concept study was to determine the sensitivity and specificity of ultrasound for the diagnosis of tuberculosis in adults. METHODS: Comprehensive thoracic and focused abdominal ultrasound examinations were performed by trained radiologists and pulmonologists on adults recruited from a community multimorbidity survey and a primary healthcare clinic in KwaZulu-Natal Province, South Africa. Sputum samples were systematically collected from all participants. Sensitivity and specificity of ultrasound to detect tuberculosis were calculated compared to a reference standard of i) bacteriologically-confirmed tuberculosis, and ii) either bacteriologically-confirmed or radiologic tuberculosis. RESULTS: Among 92 patients (53 [58%] male, mean age 41.9 [standard deviation 13.7] years, 49 [53%] HIV positive), 34 (37%) had bacteriologically-confirmed tuberculosis, 8 (9%) had radiologic tuberculosis with negative bacteriologic studies, and 50 (54%) had no evidence of active tuberculosis. Ultrasound abnormalities on either thoracic or abdominal exams were detected in 31 (91%) participants with bacteriologic tuberculosis and 27 (54%) of those without tuberculosis. Sensitivity and specificity of any ultrasound abnormality for bacteriologically-confirmed tuberculosis were 91% (95% confidence interval [CI] 76%-98%) and 46% (95% CI 32%-61%). Sensitivity and specificity of any ultrasound abnormality for either bacteriologically-confirmed or radiologic tuberculosis were 86% (95% CI 71%-95%) and 46% (95% CI 32%-61%). Overall performance did not appear to differ markedly between participants with and without HIV. CONCLUSION: A comprehensive ultrasound scanning protocol in adults in a high TB burden setting had high sensitivity but low specificity to identify bacteriologically-confirmed tuberculosis
Clinic presentation delay and tuberculosis treatment outcomes in the Lake Victoria region of East Africa: A multi-site prospective cohort study.
No full textIn the Lake Victoria region of East Africa, little is known about delays between tuberculosis (TB) symptom onset and presentation at a clinic. Associations between clinic presentation delay and TB treatment outcomes are also poorly understood. In 2019, we abstracted data from routine TB treatment records for all adults (n = 776) initiating TB treatment in a 6-month period across 12 health facilities near Lake Victoria. We interviewed 301 cohort members and assessed whether they experienced a clinic presentation delay longer than 6 weeks. We investigated potential clinical and demographic correlates of clinic presentation delay and examined the association between clinic presentation delay and an unfavorable TB treatment outcome (death, loss to follow-up, or treatment failure). Clinic presentation delay was common, occurring among an estimated 54.7% (95% CI: 48.9%, 61.2%) of cohort members, though no specific correlates were identified. Clinic presentation delay was slightly associated with unfavorable TB treatment outcomes. The 180-day risk of an unfavorable outcome was 14.2% (95% CI: 8.0%, 20.4%) among those with clinic presentation delay, compared to 12.7% (95% CI: 5.1%, 20.3%) among those presenting earlier. Multi-level community-based interventions may be necessary to reduce clinic presentation delays in communities near Lake Victoria
Factors associated with antiretroviral therapy adherence among adolescents living with HIV in the era of isoniazid preventive therapy as part of HIV care
No full textHigh levels of adherence to antiretroviral therapy (ART) are essential to promoting viral suppression and consequential good treatment outcomes. Adolescents living with HIV (ALHIV) in sub-Saharan Africa are less adherent to ART compared to adults, leading to lower rates of viral suppression and immunological recovery. We conducted a mixed-method study utilizing a convergent parallel approach to explore factors associated with ART adherence among ALHIV in the era of isoniazid preventive therapy (IPT) as part of HIV care. The quantitative data were collected from patient records from the period between 1 February 2017 and 31 January 2018 (6 months before and after IPT introduction), while qualitative data was collected from purposively selected patients and healthcare workers by in-depth interviews through a pretested interview guide. A total of 385 patient records (age 10–19 years) were analyzed in the two time periods, while 16 ALHIV (age 10–19 years) and three healthcare workers directly involved in adolescent care were interviewed. Quantitative data utilized logistic regression to measure the strength of association between IPT addition and ART adherence, whereas, qualitative data were analyzed using a thematic analysis approach. The mean age of participants in the quantitative section was 14.3 years (SD 2.7) and 178 were females, while the median age for adolescents interviewed was 14 (IQR 12–17) and 8 were females. Overall, we found an interaction of factors that influenced ART adherence. Added pill burden, on its own, did not affect ART adherence. Commonly reported factors that led to poor adherence were lack of status disclosure within the family, school pressure, and inadequate support from guardians and parents. According to retrospective patient records, complex ART regimens also worsened adherence (p = 0.0462). ART regimen was independently associated with adherence (OR 2.11 95% CI 0.97–4.53). Being on ART for a longer duration, enrolment into teen clubs, clinical psychosocial support, and self-reinforcement techniques were suggested to improve ART adherence. The interplay of multiple factors leads to poor rates of adherence. The introduction of IPT to ART packages may not independently affect ART adherence. Readily available psychosocial services and the presence of peer and guardian support is critical to optimal ART adherence. There is a need for ART centers that provide HIV care to adolescents to consider integrating psychosocial and other youth-friendly services into day-to-day clinic operations
Geophysical estimation of free-phase gas content and distribution in peatlands
No full textEmissions of methane and carbon dioxide gases from organic soils contribute to the global carbon cycle and may influence climate change. Revealing where these gases accumulate in the subsurface of saturated peat soils is a critical step towards understanding carbon cycling through peatlands. This dissertation presents field and laboratory geophysical investigations of free-phase gas contained within peatlands. Ground-penetrating radar (GPR) was used to estimate the vertical distribution of free- phase gas (FPG) in sites within the Glacial Lake Agassiz Peatland, MN. Bog-crest landforms were characterized by vertical variability in FPG and accumulations up to 24% FPG within the intervals 2-4 m deep. Lawn sites show lower volumes up to 12% FPG and a more even vertical gas distribution. These results demonstrate that spatial distribution of FPG varies vertically in the peat of Glacial Lake Agassiz peatlands depending on landform type. A second study was designed to elucidate spatial variability in FPG two-dimensionally along a transect crossing a bog crest, mid-slope lawn, and fen peat landforms. Variability in gas content and distribution was observed using GPR as a function of peat landform type. Estimated gas content up to 25% was observed in landforms dominated by woody surface vegetation. In the lawn, estimated gas content was > 15%, while estimated gas contents between 0% - 7% were found in the fen. Changes in gas content of up to 20% were observed over a transition between a stand of 10 m tall trees and a fen. These results support conceptual models based on accumulation and storage of FPG. Models relating geophysical measurements to pore water content limit the accuracy of FPG estimates. To improve these models, the dielectric properties of peat samples were measured in response to changes in water content. Dielectric permittivity was measured using GPR at water contents between 0.87 and 0.95 m3 m-3 on four samples with varying levels of humification. The resulting relationships indicate that there are differences in the permittivity-water content relationships between peat samples. Behavior of parameters in the dielectric mixing model indicates that variability in dielectric relationships may be attributed to peat structure.Ph.D.Includes bibliographical referencesIncludes vitaby Andrew D Parsekia
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