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"HADLEY, David"
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Comparison of QT Interval Measurement Methods and Correction Formulas in Atrial Fibrillation
2019
Antiarrhythmic drugs used in atrial fibrillation (AF) cause QT prolongation and are associated with torsades de pointes, a deadly ventricular arrhythmia. No consensus exists on the optimal method of QT measurement or correction in AF. Therefore, we compared common methods to measure and correct QT in AF to identify the most accurate approach. We identified patients who had electrocardiograms done at Stanford Hospital (Stanford, California) between January 2014 and October 2016 with conversion from AF to sinus rhythm (SR) within a 24-hour period. QT intervals were determined using different measurement methods and corrected using the Bazett's, Framingham, Fridericia, or Hodges formulas for heart rate (HR). Comparisons were made between QT in a patient's last instance of AF to SR. Computerized measurements were taken from 715 patients. Manual measurements were taken from a 50-patient subset. Bazett's formula produced the longest corrected QT in AF compared with other formulas (p <0.005). Measuring QT as an average over multiple beats resulted in a smaller difference between AF and SR than choosing a single beat. Determining QT from a 5-beat average resulted in a QTc that was 19.0 ms higher (interquartile range 0.30 to 43.7) in AF than SR. After correcting for residual effect of HR on QTc, there was not a significant difference between QTc in AF to SR. In conclusion, measuring QT over multiple beats produces a more accurate measurement of QT in AF. Differences between QTc in AF and SR exist because of imperfect HR correction formula and not due to an independent effect of AF.
Journal Article
ECOSYSTEM SERVICES AND ECONOMIC THEORY: INTEGRATION FOR POLICY-RELEVANT RESEARCH
by
Ferraro, Paul
,
Green, Rhys
,
Fisher, Brendan
in
benefits capture
,
conservation
,
Conservation of Natural Resources
2008
It has become essential in policy and decision-making circles to think about the economic benefits (in addition to moral and scientific motivations) humans derive from well-functioning ecosystems. The concept of ecosystem services has been developed to address this link between ecosystems and human welfare. Since policy decisions are often evaluated through cost—benefit assessments, an economic analysis can help make ecosystem service research operational. In this paper we provide some simple economic analyses to discuss key concepts involved in formalizing ecosystem service research. These include the distinction between services and benefits, understanding the importance of marginal ecosystem changes, formalizing the idea of a safe minimum standard for ecosystem service provision, and discussing how to capture the public benefits of ecosystem services. We discuss how the integration of economic concepts and ecosystem services can provide policy and decision makers with a fuller spectrum of information for making conservation—conversion trade-offs. We include the results from a survey of the literature and a questionnaire of researchers regarding how ecosystem service research can be integrated into the policy process. We feel this discussion of economic concepts will be a practical aid for ecosystem service research to become more immediately policy relevant.
Journal Article
Options for Forest Sector Participation in International Carbon Markets: Unlocking the Carbon Market Potential of Australia’s Forest Sector
by
Ximenes, Fabiano
,
Hadley, David
,
Suitor, Shaun
in
Air quality management
,
Australian Carbon Credit Units Scheme
,
Biodiversity
2025
Carbon markets have emerged as a central component of international climate change policies. Within these markets, forest carbon offset projects have become a key nature-based solution due to their low cost, large scale, and co-benefits. However, despite Australia’s vast forest estate, forest sector-specific offsets remain nascent in the Australian Carbon Market, the ACCU Scheme. Only 3.27% of Australian Carbon Credit Units have been issued to forest sector projects. This limited participation can be attributed to several constraints within the ACCU Scheme, principally the limited number of methods available for the forest sector to engage in. As a result, less than 1% of Australia’s current forest estate, both plantation and native forests, is considered eligible to participate in the ACCU Scheme. This limited eligibility is further compounded by the complexity and cost of participation, which act as significant barriers for forest projects within the ACCU Scheme. This paper explores the potential to expand forest sector involvement in the Australian carbon market through a comprehensive literature review of forest sector involvement in international carbon markets. The review found extensive participation by the forest sector in international carbon markets, with various methods available across 20 markets, including the largest voluntary and compliance markets. These methods cover plantation forests, native forests, the bioeconomy, and the built environment. Key results indicate that revising existing methods, developing new ones through the ACCU Scheme’s proponent-led method development process, and increasing participation in international voluntary methods could significantly expand the types of forest sector projects contributing to emissions reductions through carbon markets. Broader conclusions suggest that by embracing lessons from international practises and addressing current methodological constraints, Australia can realise this potential. Doing so would not only bolster the nation’s climate change mitigation efforts, but also unlock the co-benefits of biodiversity, water quality, soil productivity, and ecosystem resilience, ultimately contributing to a sustainable and resilient bioeconomy.
Journal Article
Patterns and prognosis of all components of the J-wave pattern in multiethnic athletes and ambulatory patients
2014
Despite recent concern about the significance of the J-wave pattern (also often referred to as early repolarization) and the importance of screening in athletes, there are limited rigorous prognostic data characterizing the 3 components of the J-wave pattern (ST elevation, J waves, and QRS slurs). We aim to assess the prevalence, patterns, and prognosis of the J-wave pattern among both stable clinical and athlete populations.
We retrospectively studied 4,041 electrocardiograms from a multiethnic clinical population from 1997 to 1999 at the Veterans Affairs Palo Alto Health Care System. We also examined preparticipation electrocardiograms of 1,114 Stanford University varsity athletes from 2007 to 2008. Strictly defined criteria for components of the J-wave pattern were examined. In clinical subjects, prognosis was assessed using the end point of cardiovascular death after 7 years of follow-up.
Components of the J-wave pattern were most prevalent in males; African Americans; and, particularly, athletes, with the greatest variations demonstrated in the lateral leads. ST elevation was the most common. Inferior J waves and slurs, previously linked to cardiovascular risk, were observed in 9.6% of clinical subjects and 12.3% of athletes. J waves, slurs, or ST elevation was not associated with time to cardiovascular death in clinical subjects, and ST-segment slope abnormalities were not prevalent enough in conjunction with them to reach significance.
J waves, slurs, or ST elevation was not associated with increased hazard of cardiovascular death in our large multiethnic, ambulatory population. Even subsets of J-wave patterns, recently proposed to pose a risk of arrhythmic death, occurred at such a high prevalence as to negate their utility in screening.
Journal Article
Identification of Non-HLA Genes Associated with Celiac Disease and Country-Specific Differences in a Large, International Pediatric Cohort
2016
There are significant geographical differences in the prevalence and incidence of celiac disease that cannot be explained by HLA alone. More than 40 loci outside of the HLA region have been associated with celiac disease. We investigated the roles of these non-HLA genes in the development of tissue transglutaminase autoantibodies (tTGA) and celiac disease in a large international prospective cohort study.
A total of 424,788 newborns from the US and European general populations and first-degree relatives with type 1 diabetes were screened for specific HLA genotypes. Of these, 21,589 carried 1 of the 9 HLA genotypes associated with increased risk for type 1 diabetes and celiac disease; we followed 8676 of the children in a 15 y prospective follow-up study. Genotype analyses were performed on 6010 children using the Illumina ImmunoChip. Levels of tTGA were measured in serum samples using radio-ligand binding assays; diagnoses of celiac disease were made based on persistent detection of tTGA and biopsy analysis. Data were analyzed using Cox proportional hazards analyses.
We found 54 single-nucleotide polymorphisms (SNPs) in 5 genes associated with celiac disease (TAGAP, IL18R1, RGS21, PLEK, and CCR9) in time to celiac disease analyses (10-4>P>5.8x10-6). The hazard ratios (HR) for the SNPs with the smallest P values in each region were 1.59, 1.45, 2.23, 2.64, and 1.40, respectively. Outside of regions previously associated with celiac disease, we identified 10 SNPs in 8 regions that could also be associated with the disease (P<10-4). A SNP near PKIA (rs117128341, P = 6.5x10-8, HR = 2.8) and a SNP near PFKFB3 (rs117139146, P<2.8x10-7, HR = 4.9) reached the genome-wide association threshold in subjects from Sweden. Analyses of time to detection of tTGA identified 29 SNPs in 2 regions previously associated with celiac disease (CTLA4, P = 1.3x10-6, HR = 0.76 and LPP, P = 2.8x10-5, HR = .80) and 6 SNPs in 5 regions not previously associated with celiac disease (P<10-4); non-HLA genes are therefore involved in development of tTGA.
In conclusion, using a genetic analysis of a large international cohort of children, we associated celiac disease development with 5 non-HLA regions previously associated with the disease and 8 regions not previously associated with celiac disease. We identified 5 regions associated with development of tTGA. Two loci associated with celiac disease progression reached a genome-wide association threshold in subjects from Sweden.
Journal Article
Open reconstruction of recurrent vesicourethral anastomotic stricture after radical prostatectomy
by
Knoll, Paul
,
Blakely, Stephen A.
,
Windsperger, Andrew P.
in
Aged
,
Anastomosis, Surgical - adverse effects
,
Follow-Up Studies
2014
Objectives
To determine the outcomes of open vesicourethral anastomotic reconstruction (VUAR) for outlet stenosis following radical prostatectomy (RP).
Methods
Review of all cases of VUAR within an IRB-approved database was performed. Preoperative factors assessed included cancer treatment modality, duration of symptoms, prior treatments, and length of defect. Outcomes reviewed included length-of-stay (LOS), complications, maintenance of patency, continence, and need for additional procedures.
Results
Twelve cases of VUAR performed by a single surgeon (BJF) from 2004 to 2012 were identified. Surgical approaches were either abdominal (7), perineal (3), or abdominoperineal (2). All patients underwent prior RP, with 25 % having subsequent radiotherapy. Among patients with stenosis, 43 % were completely obliterated. Two cases had prior anastomotic disruption in the early postoperative period after RP. The median length of stenosis was 2.5 cm (range 1–5 cm) and median LOS was 3.0 days (range 1–7 days). At a median follow-up of 75.5 months (range 14–120 months), 92 % of men retained patency; only 25 % were continent.
Conclusion
In experienced hands, VUAR can restore durable patency for men afflicted with outlet stenosis after RP. Despite anatomic restoration, incontinence is likely.
Journal Article
Effect of Financial Inclusion on Poverty and Vulnerability to Poverty: Evidence Using a Multidimensional Measure of Financial Inclusion
by
Villano, Renato A.
,
Hadley, David
,
Koomson, Isaac
in
Banking
,
Correspondence analysis
,
Developing countries
2020
This study examines the effect of financial inclusion on poverty and vulnerability to poverty of Ghanaian households. Using data extracted from the seventh round of the Ghana Living Standards Survey in 2016/17, a multiple correspondence analysis is employed to generate a financial inclusion index, and three-stage feasible least squares is used to estimate households’ vulnerability to poverty. Endogeneity associated with financial inclusion is resolved using distance to the nearest bank as an instrument in an instrumental variables probit technique. Results showed that while 23.4% of Ghanaians are considered poor, about 51% are vulnerable to poverty. We found that an increase in financial inclusion has two effects on household poverty. First, it is associated with a decline in a household’s likelihood of being poor by 27%. Second, it prevents a household’s exposure to future poverty by 28%. Female-headed households have a greater chance of experiencing a larger reduction in poverty and vulnerability to poverty through enhanced financial inclusion than do male-headed households. Furthermore, financial inclusion reduces poverty and vulnerability to poverty more in rural than in urban areas. Governments are encouraged to design or enhance policies that provide an enabling environment for the private sector to innovate and expand financial services to more distant places. Government investment in, and regulation of, the mobile money industry will be a necessary step to enhancing financial inclusion in developing countries.
Journal Article
Effects of exercise training on heart rate recovery in patients with chronic heart failure
by
Myers, Jonathan
,
Kottman, Wilhard
,
Hadley, David
in
Analysis of Variance
,
Biological and medical sciences
,
Blood pressure
2007
Heart rate recovery (HRR) is a marker of vagal tone that is associated with survival, but little is known about the effects of exercise training on HRR in patients with heart failure (HF).
Twenty-four patients with HF were randomized to a 2-month residential rehabilitation program or to usual care. Symptom-limited exercise testing was performed at baseline and at discharge from the program. Heart rate recovery was expressed as the decline in heart rate from peak exercise through 6 minutes into recovery. In addition, HRR recovery curves were normalized to a range of 1 at peak heart rate and 0 at 6 minutes and adjusted for differences in heart rate reserve, facilitating the comparison of recovery curve shapes between groups.
Mean peak oxygen uptake and oxygen uptake at the lactate threshold increased 26% (
P < .05) and 39% (
P < .001), respectively, in the exercise group, whereas neither of these responses changed significantly among controls. Heart rate recovery was significantly more rapid in the exercise group after training (main effect 12.6 vs 2.6 beat/min in the trained and control groups, respectively,
P = .005). The normalized curves showed that the largest improvement in recovery curve shape occurred in the exercise group, but most of the HRR improvement was accounted for by a widening of the difference between peak and resting heart rate.
Exercise training results in a faster HRR in patients with HF. Heart rate recovery, as a simple marker of autonomic function, is an easily acquired response that may be useful for evaluating patient outcomes in cardiac rehabilitation.
Journal Article
Impact of the distance from the chest wall to the heart on surface ECG voltage in athletes
by
Hedman, Kristofer
,
Froelicher, Victor
,
Christle, Jeffrey W
in
Athletes
,
athlete’s heart
,
Electrocardiography
2020
ObjectiveAvailable ECG criteria for detection of left ventricular (LV) hypertrophy have been reported to have limited diagnostic capability. Our goal was to describe how the distance between the chest wall and the left ventricle determined by echocardiography affected the relationship between ECG voltage and LV mass (LVM) in athletes.MethodsWe retrospectively evaluated digitised ECG data from college athletes undergoing routine echocardiography as part of their preparticipation evaluation. Along with LV mass and volume, we determined the chest wall–LV distance in the parasternal short-axis and long-axis views from two-dimensional transthoracic echocardiographic images and explored the relation with ECG QRS voltages in all leads, as well as summed voltages as included in six major ECG-LVH criteria.Results239 athletes (43 women) were included (age 19±1 years). In men, greater LV–chest wall distance was associated with higher R-wave amplitudes in leads aVL and I (R=0.20 and R=0.25, both p<0.01), while in women greater distance was associated with higher R-amplitudes in V5 and V6 (R=0.42 and R=0.34, both p<0.01). In women, the chest wall–LV distance was the only variable independently (and positively) associated with R V5 voltage, while LVM, height and weight contributed to the relationship in men.ConclusionsThe chest wall–LV distance was weakly associated with ECG voltage in athletes. Inconsistent associations in men and women imply different intrathoracic factors affecting impedance and conductance between sexes. This may help explain the poor relationship between QRS voltage and LVM in athletes.
Journal Article
Bringing Ecosystem Services into Economic Decision-Making: Land Use in the United Kingdom
by
Haines-Young, Roy
,
Fezzi, Carlo
,
Day, Brett H.
in
Agricultural ecosystems
,
Agricultural policy
,
Agricultural production
2013
Landscapes generate a wide range of valuable ecosystem services, yet land-use decisions often ignore the value of these services. Using the example of the United Kingdom, we show the significance of land-use change not only for agricultural production but also for emissions and sequestration of greenhouse gases, open-access recreational visits, urban green space, and wild-species diversity. We use spatially explicit models in conjunction with valuation methods to estimate comparable economic values for these services, taking account of climate change impacts. We show that, although decisions that focus solely on agriculture reduce overall ecosystem service values, highly significant value increases can be obtained from targeted planning by incorporating all potential services and their values and that this approach also conserves wild-species diversity.
Journal Article