Publications by authors named "Jim Burch"

4 Publications

  • Page 1 of 1

Turbulence-Driven Ion Beams in the Magnetospheric Kelvin-Helmholtz Instability.

Phys Rev Lett 2019 Jan;122(3):035102

Swedish Institute of Space Physics, Uppsala SE-751 05, Sweden.

The description of the local turbulent energy transfer and the high-resolution ion distributions measured by the Magnetospheric Multiscale mission together provide a formidable tool to explore the cross-scale connection between the fluid-scale energy cascade and plasma processes at subion scales. When the small-scale energy transfer is dominated by Alfvénic, correlated velocity, and magnetic field fluctuations, beams of accelerated particles are more likely observed. Here, for the first time, we report observations suggesting the nonlinear wave-particle interaction as one possible mechanism for the energy dissipation in space plasmas.
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http://dx.doi.org/10.1103/PhysRevLett.122.035102DOI Listing
January 2019

Incidence and predictive factors of Balkan endemic nephropathy: a longitudinal study.

Saudi J Kidney Dis Transpl 2014 Mar;25(2):343-52

Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, South Carolina, USA.

Balkan endemic nephropathy (BEN) is a chronic kidney disease that progresses slowly. There are no known clinical markers to identify an early disease development. We evaluated the relationship between parental history of BEN and clinical markers as predictors of new occurrences of BEN. A 5-year prospective study in the offsprings of BEN and control patients was conducted in Vratza, Bulgaria, between 2003 and 2009 using markers in years one and three to predict new cases of BEN in the year five. We defined incident cases of BEN based on parental history, reduced kidney size and reduced kidney function, distinguishing probable and definite BEN, both combined as total incidence. The data were analyzed by Cox regression models using age as time scale and controlling for gender. We estimated hazard ratios and their 95% confidence intervals. The incidence of BEN was 17.4%. Paternal history was strongly associated with all three incidence groups (hazards ratio: 27-68, P <0.05). A reduction of kidney size of 1 mm resulted in a 5% increased hazard. However, taking parental history of BEN into account, these associations lost their significance. No kidney function measures were associated with new onset of BEN. A parental history of BEN is more important than clinical markers predicting the incidence of BEN. Without this information, kidney length forecasts probable BEN and the total incidence, while none of any clinical markers was related to definite BEN.
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http://dx.doi.org/10.4103/1319-2442.128539DOI Listing
March 2014

A case-referent study: light at night and breast cancer risk in Georgia.

Int J Health Geogr 2013 Apr 17;12:23. Epub 2013 Apr 17.

Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, Athens, GA, USA.

Background: Literature has identified detrimental health effects from the indiscriminate use of artificial nighttime light. We examined the co-distribution of light at night (LAN) and breast cancer (BC) incidence in Georgia, with the goal to contribute to the accumulating evidence that exposure to LAN increases risk of BC.

Methods: Using Georgia Comprehensive Cancer Registry data (2000-2007), we conducted a case-referent study among 34,053 BC cases and 14,458 lung cancer referents. Individuals with lung cancer were used as referents to control for other cancer risk factors that may be associated with elevated LAN, such as air pollution, and since this cancer type was not previously associated with LAN or circadian rhythm disruption. DMSP-OLS Nighttime Light Time Series satellite images (1992-2007) were used to estimate LAN levels; low (0-20 watts per sterradian cm(2)), medium (21-41 watts per sterradian cm(2)), high (>41 watts per sterradian cm(2)). LAN levels were extracted for each year of exposure prior to case/referent diagnosis in ArcGIS.

Results: Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression models controlling for individual-level year of diagnosis, race, age at diagnosis, tumor grade, stage; and population-level determinants including metropolitan statistical area (MSA) status, births per 1,000 women aged 15-50, percentage of female smokers, MSA population mobility, and percentage of population over 16 in the labor force. We found that overall BC incidence was associated with high LAN exposure (OR = 1.12, 95% CI [1.04, 1.20]). When stratified by race, LAN exposure was associated with increased BC risk among whites (OR = 1.13, 95% CI [1.05, 1.22]), but not among blacks (OR = 1.02, 95% CI [0.82, 1.28]).

Conclusions: Our results suggest positive associations between LAN and BC incidence, especially among whites. The consistency of our findings with previous studies suggests that there could be fundamental biological links between exposure to artificial LAN and increased BC incidence, although additional research using exposure metrics at the individual level is required to confirm or refute these findings.
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http://dx.doi.org/10.1186/1476-072X-12-23DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3651306PMC
April 2013

The role of a parental history of Balkan endemic nephropathy in the occurrence of BEN: a prospective study.

Int J Nephrol Renovasc Dis 2012 4;5:61-8. Epub 2012 Apr 4.

Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA.

Balkan endemic nephropathy (BEN) is a chronic kidney disease that affects persons living in the Balkans. Despite the unique geographical specificity of this disease, its etiology has remained unclear. Even if a positive family history of BEN has been identified, it is still uncertain how the disease develops in offspring. In this paper, we examine clinical mechanisms related to the onset of BEN in individuals who have a parental history of BEN to identify early detection of the disease and formulate interventions. We conducted a 5-year prospective study, using markers in years one and three to predict new cases of BEN in year five. New cases of BEN were defined based on three criteria: parental history of BEN, reduced kidney size, and reduced kidney function. Incident cases were divided into (1) probable, (2) definite, and (3) combined labeled total incidence. We evaluated parental history in relation to BEN and tested the potentially intervening effects of kidney length, kidney cortex width, β(2)-microglobulin, C-reactive protein, and creatinine clearance, using path analyses. The findings of the path analyses suggested that parental history of BEN had both direct and indirect effects. The direct effect was significant for all three modes of parental history (biparental, maternal, and paternal; odds ratios 71.5, 52.3, and 50.1, respectively). The indirect effects of maternal BEN acted via kidney length and creatinine clearance. Biparental BEN was mediated by (1) kidney length and creatinine clearance, and (2) creatinine clearance alone. Paternal BEN had three indirect effects: (1) through kidney length and creatinine clearance, (2) via kidney cortex width and creatinine clearance, and (3) via kidney cortex width only. In conclusion, a family history of BEN led to reduced kidney length and cortex width, and a decline in creatinine clearance, which in turn predicted the onset of BEN.
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http://dx.doi.org/10.2147/IJNRD.S30615DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3333804PMC
October 2012