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Search Results: 1 - 10 of 448347 matches for " J. L. Fahey "
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A compact, fast UV photometer for measurement of ozone from research aircraft
R. S. Gao, J. Ballard, L. A. Watts, T. D. Thornberry, S. J. Ciciora, R. J. McLaughlin,D. W. Fahey
Atmospheric Measurement Techniques (AMT) & Discussions (AMTD) , 2012,
Abstract: In situ measurements of atmospheric ozone (O3) are performed routinely from many research aircraft platforms. The most common technique depends on the strong absorption of ultraviolet (UV) light by ozone. As atmospheric science advances to the widespread use of unmanned aircraft systems (UASs), there is an increasing requirement for minimizing instrument space, weight, and power while maintaining instrument accuracy, precision and time response. The design and use of a new, dual-beam, UV photometer instrument for in situ O3 measurements is described. A polarization optical-isolator configuration is utilized to fold the UV beam inside the absorption cells, yielding a 60-cm absorption length with a 30-cm cell. The instrument has a fast sampling rate (2 Hz at <200 hPa, 1 Hz at 200–500 hPa, and 0.5 Hz at ≥ 500 hPa), high accuracy (3% excluding operation in the 300–450 hPa range, where the accuracy may be degraded to about 5%), and excellent precision (1.1 × 1010 O3 molecules cm 3 at 2 Hz, which corresponds to 3.0 ppb at 200 K and 100 hPa, or 0.41 ppb at 273 K and 1013 hPa). The size (36 l), weight (18 kg), and power (50–200 W) make the instrument suitable for many UASs and other airborne platforms. Inlet and exhaust configurations are also described for ambient sampling in the troposphere and lower stratosphere (1000–50 hPa) that control the sample flow rate to maximize time response while minimizing loss of precision due to induced turbulence in the sample cell. In-flight and laboratory intercomparisons with existing O3 instruments show that measurement accuracy is maintained in flight.
Freed to Learn: Five Fundamental Concepts of Democratic Education
Leo J. Fahey
Journal of Unschooling and Alternative Learning , 2008,
Abstract: Children are natural learners each with distinct interests, abilities and rates of cognitive, emotional and social growth. Democratic Education institutionalizes five key concepts to free these natural instincts and individual differences to drive community self-governance and individual self-directed learning within a formal schooling environment. This paper summarizes the five concepts fundamental to Democratic Education and suggests how they can be applied within a school setting.
Laboratory evaluation of the effect of nitric acid uptake on frost point hygrometer performance
T. Thornberry, T. Gierczak, R. S. Gao, H. V mel, L. A. Watts, J. B. Burkholder,D. W. Fahey
Atmospheric Measurement Techniques (AMT) & Discussions (AMTD) , 2011,
Abstract: Chilled mirror hygrometers (CMH) are widely used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapour instruments have been observed at low water vapour mixing ratios (<5 ppm) in the upper troposphere and lower stratosphere (UT/LS). Understanding the source of the measurement discrepancies is important for a more accurate and reliable determination of water vapour abundance in this region. We have conducted a laboratory study to investigate the potential interference of gas-phase nitric acid (HNO3) with the measurement of frost point temperature, and consequently the water vapour mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 4 ppb for exposure times up to 150 min. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90–120 min), the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which corresponds to only a small fraction of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10%) in surface reflectivity by the condensate to determine H2O.
Prevalence of HIV Drug Resistance Mutations in HIV Type 1 Isolates in Antiretroviral Therapy Na?ve Population from Northern India
S. Sinha,H. Ahmad,R. C. Shekhar,N. Kumar,L. Dar,J. C. Samantaray,S. K. Sharma,A. Bhargava,R. M. Pandey,R. L. Mitsuyasu,J. L. Fahey
AIDS Research and Treatment , 2012, DOI: 10.1155/2012/905823
Abstract: Objective. The increased use of antiretroviral therapy (ART) has reduced the morbidity and mortality associated with HIV, adversely leading to the emergence of HIV drug resistance (HIVDR). In this study we aim to evaluate the prevalence of HIVDR mutations in ART-naive HIV-1 infected patients from northern India. Design. Analysis was performed using Viroseq genotyping system based on sequencing of entire protease and two-thirds of the Reverse Transcriptase (RT) region of pol gene. Results. Seventy three chronic HIV-1 infected ART na?ve patients eligible for first line ART were enrolled from April 2006 to August 2008. In 68 patients DNA was successfully amplified and sequencing was done. 97% of HIV-1 strains belonged to subtype C, and one each to subtype A1 and subtype B. The overall prevalence of primary DRMs was 2.9% [2/68, 95% confidence interval (CI), 0.3%–10.2%]. One patient had a major RT mutation M184V, known to confer resistance to lamivudine, and another had a major protease inhibitor (PI) mutation D30N that imparts resistance to nelfinavir. Conclusion. Our study shows that primary HIVDR mutations have a prevalence of 2.9% among ART-naive chronic HIV-1 infected individuals. 1. Introduction The national antiretroviral therapy (ART) program in India for treatment of human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) was started by National AIDS Control Organization (NACO), Ministry of Health and Family Welfare, Government of India, in April 2004. By the end of November 2009, more than 2, 50,000 patients infected with HIV had received ART under the program [1]. As per the latest report by Joint United Nations programe on HIV/AIDS (UNAIDS), prevalence of HIV in India is estimated to be 0.31%, that translates to approximately 2.31 million persons living with HIV/AIDS [2]. The current standard first-line treatment for HIV in India consists of two nucleoside reverse transcriptase inhibitors (NRTIs), zidovudine or stavudine plus lamivudine, and one nonnucleoside reverse transcriptase inhibitor (NNRTI), nevirapine or efavirenz. Regimens with protease inhibitors (PIs) are available as second-line treatment options upon failure of the first-line ART under the national program. As per the time trends for evolution of primary HIVDR suggested by Grant et al., it can be expected that the prevalence of drug resistance mutations (DRMs) may soon increase in India [3, 4]. The widespread use of ART has resulted in an increased prevalence of drug-resistant HIV strains, ranging from 10% to 20% among drug-naive patients in other countries
Aircraft observations of enhancement and depletion of black carbon mass in the springtime Arctic
J. R. Spackman, R. S. Gao, W. D. Neff, J. P. Schwarz, L. A. Watts, D. W. Fahey, J. S. Holloway, T. B. Ryerson, J. Peischl,C. A. Brock
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2010,
Abstract: Understanding the processes controlling black carbon (BC) in the Arctic is crucial for evaluating the impact of anthropogenic and natural sources of BC on Arctic climate. Vertical profiles of BC mass loadings were observed from the surface to near 7-km altitude in April 2008 using a Single-Particle Soot Photometer (SP2) during flights on the NOAA WP-3D research aircraft from Fairbanks, Alaska. These measurements were conducted during the NOAA-sponsored Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) project. In the free troposphere, the Arctic air mass was influenced by long-range transport from biomass-burning and anthropogenic source regions at lower latitudes especially during the latter part of the campaign. Average BC mass mixing ratios peaked at about 150 ng BC (kg dry air ) 1 near 5.5 km altitude in the aged Arctic air mass and 250 ng kg 1 at 4.5 km in biomass-burning influenced air. BC mass loadings were enhanced by up to a factor of 5 in biomass-burning influenced air compared to the aged Arctic air mass. At the bottom of some of the profiles, positive vertical gradients in BC were observed over the sea-ice. The vertical profiles generally occurred in the vicinity of open leads in the sea-ice. In the aged Arctic air mass, BC mass loadings more than doubled with increasing altitude within the ABL and across the boundary layer transition while carbon monoxide (CO) remained constant. This is evidence for depletion of BC mass in the ABL. BC mass loadings were positively correlated with O3 in ozone depletion events (ODEs) for all the observations in the ABL. Since bromine catalytically destroys ozone in the ABL after being released as molecular bromine in regions of new sea-ice formation at the surface, the BC–O3 correlation suggests that BC particles were removed by a surface process such as dry deposition. We develop a box model to estimate the dry deposition flux of BC mass to the snow constrained by the vertical profiles of BC mass in the ABL. Open leads in the sea-ice may increase vertical mixing and entrainment of pollution from the free troposphere possibly enhancing the deposition of BC aerosol to the snow.
The inter-observer agreement of examining pre-school children with acute cough: a nested study
Alastair D Hay, Andrew Wilson, Tom Fahey, Tim J Peters
BMC Family Practice , 2004, DOI: 10.1186/1471-2296-5-4
Abstract: A nested study comparing two clinical assessments within a prospective cohort of 256 pre-school children with acute cough recruited from eight general practices in Leicestershire, UK. We examined agreement (using kappa statistics) between unstandardised and standardised clinical assessments of tachypnoea, chest signs and fever.Kappa values were poor or fair for all clinical signs (range 0.12 to 0.39) with chest signs the most reliable.Primary care clinicians should be aware that clinical signs may be unreliable when making diagnosis, prognosis and treatment decisions in pre-school children with cough. Future research should aim to further our understanding of how best to identify abnormal clinical signs.Cough is the most frequently managed problem in primary care and becomes increasingly common at the extremes of age [1,2]. Cough in pre-school children is usually due to simple, self limiting respiratory tract infection, but more severe causes need to be ruled out including pneumonia, bronchiolitis, pertussis, croup and asthma[2]. The presence of clinical signs may have diagnostic, prognostic, and treatment implications. The absence of tachypnoea has been shown to be most useful for ruling out pneumonia[3], and fever is associated with poor outcome in children with cough[4] and otitis media[5]. In a study of cough in adults, antibiotics were eight times more likely to be prescribed in patients with abnormal chest signs[6], and in another study 93% of adults presenting with the combination of cough and chest signs received antibiotics[7].The reliability and accuracy of respiratory symptoms and signs have been assessed almost exclusively in secondary care[8], where relatively serious illness is more prevalent[9]. Given the diagnostic, prognostic and treatment implications of these clinical signs, we decided to examine the inter-observer agreement between a standardised and non-standardised clinical assessment in pre-school children presenting with acute cough in primar
Randomized trial evaluating the framing of cardiovascular risk and its impact on blood pressure control [ISRCTN87597585]
Tom Fahey, Alan A Montgomery, Tim J Peters
BMC Health Services Research , 2001, DOI: 10.1186/1472-6963-1-10
Abstract: We recruited 457 patients aged between 60 and 79 years with high blood pressure from 20 family practices in Avon, UK. Patients were randomized to cardiovascular risk presented either as 1) an absolute risk level (AR) or as 2) the number needed to treat to prevent an adverse event (NNT). The main outcome measures were: 1) percentage of patients in each group with a five-year cardiovascular risk ≥ 10%, 2) systolic and diastolic blood pressure, 3) intensity of prescribing of cardiovascular medication.Presenting cardiovascular risk as either an AR or NNT had no impact reducing cardiovascular risk at 12 month follow up, adjusted odds ratio 1.53 (95%CI 0.76 to 3.08). There was no difference between the two groups in systolic (adjusted difference 0.97 mmHg, 95%CI -2.34 mmHg to 4.29 mmHg) or diastolic (adjusted difference 0.70 mmHg, 95%CI -1.05 mmHg to 2.45 mmHg) blood pressure. Intensity of prescribing of blood pressure lowering drugs was not significantly different between the two groups at six months follow up.Presenting cardiovascular risk in clinical practice guidelines as either an AR or NNT had a similar influence on patient outcome and prescribing intensity. There is no difference in patient outcomes when these alternative formats of risk are used in clinical practice guidelines.The results of randomized controlled trials (RCTs) and clinical practice guidelines are based on data that estimate, in numeric terms, the benefits and risks of treatment [1]. Data can be presented in a number of different formats: as an absolute risk level (AR), an absolute risk reduction (ARR), a relative risk reduction (RRR) or as the number of patients who need to be treated in order that an adverse event is prevented (NNT) [2-4]. (see Figure 1 for an example of how different formats of risk can be calculated)Studies of self reported practice demonstrate that interpretation by physicians of numeric data may vary depending on the format or the "frame" in which they are presented [1]. In c
Pathogen detection, testing, and control in fresh broccoli sprouts
Jed W Fahey, Philippe J Ourisson, Frederick H Degnan
Nutrition Journal , 2006, DOI: 10.1186/1475-2891-5-13
Abstract: A one year program of microbial hold-and-release testing, conducted in concert with strict seed and facility cleaning procedures by 13 U.S. broccoli sprout growers was evaluated. Microbial contamination tests were performed on 6839 drums of sprouts, equivalent to about 5 million consumer packages of fresh green sprouts.Only 24 (0.75%) of the 3191 sprout samples gave an initial positive test for Escherichia coli O157:H7 or Salmonella spp., and when re-tested, 3 drums again tested positive. Composite testing (e.g., pooling up to 7 drums for pathogen testing) was equally sensitive to single drum testing.By using a "test-and-re-test" protocol, growers were able to minimize crop destruction. By pooling drums for testing, they were also able to reduce testing costs which now represent a substantial portion of the costs associated with sprout growing. The test-and-hold scheme described herein allowed those few batches of contaminated sprouts to be found prior to packaging and shipping. These events were isolated, and only safe sprouts entered the food supply.Green sprouts have been a part of the human diet for much of recorded history. Their commercial production has been a small niche industry in the U.S. for the past 30 or so years, but they are much more widely consumed in countries like Japan, where they are part of mainstream diets. In the past 8 years broccoli sprouts have gained increased scientific attention due to their high content of phytochemicals that are involved in protection against cancer and other degenerative diseases [1-7].Industry experts estimate that about 15 million pounds of fresh green sprouts are now grown in the U.S. annually and the vast majority of these are alfalfa sprouts. Sprouts are grown from seeds placed in environmentally controlled, hydroponic conditions and incubated in warm, moist, nutrient-rich conditions [1.5 m. diameter, slowly rotating "drums" charged with ca. 20 kg of seed], which are ideal environments for microbial growth. If
A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry Mechanisms
G. Sarwar,J. Godowitch,B. Henderson,K. Fahey
Atmospheric Chemistry and Physics Discussions , 2013, DOI: 10.5194/acpd-13-6923-2013
Abstract: We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2) into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU). Compared to CB05TU, RACM2 enhances the domain-wide monthly mean hydroxyl radical concentrations by 46% and nitric acid by 26%. However, it reduces hydrogen peroxide by 2%, peroxyacetic acid by 94%, methyl hydrogen peroxide by 19%, peroxyacetyl nitrate by 40%, and organic nitrate by 41%. RACM2 predictions generally agree better with the observed data than the CB05TU predictions. RACM2 enhances ozone for all ambient levels leading to higher bias at low (< 60 ppbv) concentrations but improved performance at high (>70 ppbv) concentrations. The RACM2 ozone predictions are also supported by increased ozone production efficiency that agrees better with observations. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean sulfate by 10%, nitrate by 6%, ammonium by 10%, anthropogenic secondary organic aerosols by 42%, biogenic secondary organic aerosols by 5%, and in-cloud secondary organic aerosols by 7%. Increased inorganic and organic aerosols with RACM2 agree better with observed data. While RACM2 enhances ozone and secondary aerosols by relatively large margins, control strategies developed for ozone or fine particles using the two mechanisms do not differ appreciably.
Quantification of (1→4)-β-d-Galactans in Compression Wood Using an Immuno-Dot Assay
Ramesh R. Chavan,Leona M. Fahey,Philip J. Harris
Plants , 2015, DOI: 10.3390/plants4010029
Abstract: Compression wood is a type of reaction wood formed on the underside of softwood stems when they are tilted from the vertical and on the underside of branches. Its quantification is still a matter of some scientific debate. We developed a new technique that has the potential to do this based on the higher proportions of (1→4)-β-d-galactans that occur in tracheid cell walls of compression wood. Wood was milled, partially delignified, and the non-cellulosic polysaccharides, including the (1→4)-β-d-galactans, extracted with 6 M sodium hydroxide. After neutralizing, the solution was serially diluted, and the (1→4)-β-d-galactans determined by an immuno-dot assay using the monoclonal antibody LM5, which specifically recognizes this polysaccharide. Spots were quantified using a dilution series of a commercially available (1→4)-β-d-galactan from lupin seeds. Using this method, compression and opposite woods from radiata pine ( Pinus radiata) were easily distinguished based on the amounts of (1→4)-β-d-galactans extracted. The non-cellulosic polysaccharides in the milled wood samples were also hydrolysed using 2 M trifluoroacetic acid followed by the separation and quantification of the released neutral monosaccharides by high performance anion exchange chromatography. This confirmed that the compression woods contained higher proportions of galactose-containing polysaccharides than the opposite woods.
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