227 research outputs found
A Khandani Perspective: Room for a (Long) View
Abstract: A half century personal overview
of my study of Hindustani musicians generally, and my teacher specifically
provides the context and explanation for what I aver as the distinctive features
of Hindustani music. First, the music practice did not require colonial
reconfigurations from the perspective of its hereditary khandani practitioners.
Second, for ethnomusicologists, the relationship between the researcher-disciple
and consultant-master teacher was uniquely personal and loyal. Accordingly,
despite exponentially expanding our understanding of its music practices in the
last 50 years, ethnomusicological research in India remains remarkably free of
generational friction, other than the necessary traction to learn
more.Résumé : La vue d ’ ensemble acquise au
bout d ’ un demi-siècle d ’ étude des musiciens hindoustanis en général, et
celle transmise par mon professeur en particulier, fournissent le contexte et l
’ explication de ce que j ’ affirme être les traits distinctifs de la musique
hindoustani. Premièrement, du point de vue de ses praticiens khandani
héréditaires, la pratique musicale n ’ a pas eu besoin de reconfigurations
coloniales. Deuxièmement, pour les ethnomusicologues, la relation entre le
disciple-chercheur et l ’ enseignant maître-consultant était uniquement
personnelle et faite de loyauté. Par conséquent, bien que notre compréhension de
ces pratiques musicales ait connu une croissance exponentielle au cours des
cinquante dernières années, les frictions intergénérationnelles restent
remarquablement absentes de la recherche ethnomusicologique en Inde, à l ’
exception de la nécessaire incitation à en apprendre
davantage
Nonlocal and localized analyses of conditional mean transient flow in bounded, randomly heterogeneous porous media
We consider the numerical prediction of transient flow in bounded, randomly heterogeneous porous media driven by random sources, initial heads, and boundary conditions without resorting to Monte Carlo simulation. After applying the Laplace transform to the governing stochastic flow equations, we derive exact nonlocal (integro‐differential) equations for the mean and variance‐covariance of transformed head and flux, conditioned on measured values of log conductivity Y = ln K. Approximating these conditional moment equations recursively to second order in the standard deviation σY of Y, we solve them by finite elements for superimposed mean‐uniform and convergent flows in a two‐dimensional domain. An alternative conditional mean solution is obtained through localization of the exact moment expressions. The nonlocal and localized solutions are obtained using a highly efficient parallel algorithm and inverted numerically back into the time domain. A comparison with Monte Carlo simulations demonstrates that the moment solutions are remarkably accurate for strongly heterogeneous media with σY2 as large as 4. The nonlocal solution is only slightly more accurate than the much simpler localized solution, but the latter does not yield information about predictive uncertainty. The accuracy of each solution improves markedly with conditioning. A preliminary comparison of computational efficiency suggests that both the nonlocal and localized solutions for mean head and its variance require significantly less computer time than is required for Monte Carlo statistics to stabilize when the same direct matrix solver is used for all three (we do not presently know how using iterative solvers would have affected this conclusion). This is true whether the Laplace inversion and Monte Carlo simulations are conducted sequentially or in parallel on multiple processors and regardless of problem size. The underlying exact and recursive moment equations, as well as the proposed computational algorithm, are valid in both two and three dimensions; only the numerical implementation of our algorithm is two‐dimensional
Theoretical interpretation of a pronounced permeability scale effect in unsaturated fractured tuff
Numerous single‐hole and cross‐hole pneumatic injection tests have been conducted in unsaturated fractured tuff at the Apache Leap Research Site (ALRS) near Superior, Arizona. Single‐hole tests have yielded values of air permeability at various locations throughout the tested rock volume on a nominal scale of ∼1 m. Cross‐hole tests have yielded equivalent air permeabilities (and air‐filled porosities) for a rock volume characterized by a length scale of several tens of meters. Cross‐hole tests have also provided high‐resolution tomographic estimates of how air permeability (and air‐filled porosity), defined over grid blocks having a length scale of 1 m, vary throughout a similar rock volume. The results have revealed a highly pronounced scale effect in permeability (and porosity) at the ALRS. We examine the extent to which the permeability scale effect is amenable to interpretation by a recent stochastic scaling theory, which treats the rock as a truncated random fractal
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Concentrations and Sources of Organic Carbon Aerosol in the Free Troposphere over North America
Aircraft measurements of water-soluble organic carbon (WSOC) aerosol over NE North America during summer 2004 (ITCT-2K4) are simulated with a global chemical transport model (GEOS-Chem) to test our understanding of the sources of organic carbon (OC) aerosol in the free troposphere (FT). Elevated concentrations were observed in plumes from boreal fires in Alaska and Canada. WSOC aerosol concentrations outside of these plumes average 0.9 ± 0.9 μg C m−3 in the FT (2–6 km). The corresponding model value is 0.7 ± 0.6 μg C m−3, including 42% from biomass burning, 36% from biogenic secondary organic aerosol (SOA), and 22% from anthropogenic emissions. Previous OC aerosol observations over the NW Pacific in spring 2001 (ACE-Asia) averaged 3.3 ± 2.8 μg C m−3 in the FT, compared to a model value of 0.3 ± 0.3 μg C m−3. WSOC aerosol concentrations in the boundary layer (BL) during ITCT-2K4 are consistent with OC aerosol observed at the IMPROVE surface network. The model is low in the boundary layer by 30%, which we attribute to secondary formation at a rate comparable to primary anthropogenic emission. Observed WSOC aerosol concentrations decrease by a factor of 2 from the BL to the FT, as compared to a factor of 10 decrease for sulfate, indicating that most of the WSOC aerosol in the FT originates in situ. Despite reproducing mean observed WSOC concentrations in the FT to within 25%, the model cannot account for the variance in the observations (R = 0.21). Covariance analysis of FT WSOC aerosol with other measured chemical variables suggests an aqueous-phase mechanism for SOA generation involving biogenic precursors.Earth and Planetary SciencesEngineering and Applied Science
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Classifying Complications: Assessing Adult Spinal Deformity 2-Year Surgical Outcomes.
STUDY DESIGN: Retrospective review of prospective database.
OBJECTIVE: Complication rates for adult spinal deformity (ASD) surgery vary widely because there is no accepted system for categorization. Our objective was to identify the impact of complication occurrence, minor-major complication, and Clavien-Dindo complication classification (Cc) on clinical variables and patient-reported outcomes.
METHODS: Complications in surgical ASD patients with complete baseline and 2-year data were considered intraoperatively, perioperatively (\u3c6 \u3eweeks), and postoperatively (\u3e6 weeks). Primary outcome measures were complication timing and severity according to 3 scales: complication presence (yes/no), minor-major, and Cc score. Secondary outcomes were surgical outcomes (estimated blood loss [EBL], length of stay [LOS], reoperation) and health-related quality of life (HRQL) scores. Univariate analyses determined complication presence, type, and Cc grade impact on operative variables and on HRQL scores.
RESULTS: Of 167 patients, 30.5% (n = 51) had intraoperative, 48.5% (n = 81) had perioperative, and 58.7% (n = 98) had postoperative complications. Major intraoperative complications were associated with increased EBL (
CONCLUSION: The Cc Scale was most useful in predicting changes in patient outcomes; at 2 years, patients with raised perioperative Cc scores and postoperative complications saw reduced HRQL improvement. Intraoperative and perioperative complications were associated with worse short-term surgical and inpatient outcomes
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Surface and Lightning Sources of Nitrogen Oxides over the United States: Magnitudes, Chemical Evolution, and Outflow
We use observations from two aircraft during the ICARTT campaign over the eastern United States and North Atlantic during summer 2004, interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem) to test current understanding of regional sources, chemical evolution, and export of NOx. The boundary layer NOx data provide top-down verification of a 50% decrease in power plant and industry NOx emissions over the eastern United States between 1999 and 2004. Observed NOx concentrations at 8–12 km altitude were 0.55 ± 0.36 ppbv, much larger than in previous U.S. aircraft campaigns (ELCHEM, SUCCESS, SONEX) though consistent with data from the NOXAR program aboard commercial aircraft. We show that regional lightning is the dominant source of this upper tropospheric NOx and increases upper tropospheric ozone by 10 ppbv. Simulating ICARTT upper tropospheric NOx observations with GEOS-Chem requires a factor of 4 increase in modeled NOx yield per flash (to 500 mol/flash). Observed OH concentrations were a factor of 2 lower than can be explained from current photochemical models, for reasons that are unclear. A NOy-CO correlation analysis of the fraction f of North American NOx emissions vented to the free troposphere as NOy (sum of NOx and its oxidation products) shows observed f = 16 ± 10% and modeled f = 14 ± 9%, consistent with previous studies. Export to the lower free troposphere is mostly HNO3 but at higher altitudes is mostly PAN. The model successfully simulates NOy export efficiency and speciation, supporting previous model estimates of a large U.S. anthropogenic contribution to global tropospheric ozone through PAN export.Earth and Planetary SciencesEngineering and Applied Science
Reconstruction versus conservative treatment after rupture of the anterior cruciate ligament: cost effectiveness analysis
BACKGROUND: The decision whether to treat conservatively or reconstruct surgically a torn anterior cruciate ligament (ACL) is an ongoing subject of debate. The high prevalence and associated public health burden of torn ACL has led to continuous efforts to determine the best therapeutic approach. A critical evaluation of benefits and expenditures of both treatment options as in a cost effectiveness analysis seems well-suited to provide valuable information for treating physicians and healthcare policymakers. METHODS: A literature review identified four of 7410 searched articles providing sufficient outcome probabilities for the two treatment options for modeling. A transformation key based on the expert opinions of 25 orthopedic surgeons was used to derive utilities from available evidence. The cost data for both treatment strategies were based on average figures compiled by Orthopaedic University Hospital Balgrist and reinforced by Swiss national statistics. A decision tree was constructed to derive the cost-effectiveness of each strategy, which was then tested for robustness using Monte Carlo simulation. RESULTS: Decision tree analysis revealed a cost effectiveness of 16,038 USD/0.78 QALY for ACL reconstruction and 15,466 USD/0.66 QALY for conservative treatment, implying an incremental cost effectiveness of 4,890 USD/QALY for ACL reconstruction. Sensitivity analysis of utilities did not change the trend. CONCLUSION: ACL reconstruction for reestablishment of knee stability seems cost effective in the Swiss setting based on currently available evidence. This, however, should be reinforced with randomized controlled trials comparing the two treatment strategies
Post–COVID-19 Conditions Among Children 90 Days After SARS-CoV-2 Infection
IMPORTANCE
Little is known about the risk factors for, and the risk of, developing post-COVID-19 conditions (PCCs) among children.
OBJECTIVES
To estimate the proportion of SARS-CoV-2-positive children with PCCs 90 days after a positive test result, to compare this proportion with SARS-CoV-2-negative children, and to assess factors associated with PCCs.
DESIGN, SETTING, AND PARTICIPANTS
This prospective cohort study, conducted in 36 emergency departments (EDs) in 8 countries between March 7, 2020, and January 20, 2021, included 1884 SARS-CoV-2-positive children who completed 90-day follow-up; 1686 of these children were frequency matched by hospitalization status, country, and recruitment date with 1701 SARS-CoV-2-negative controls.
EXPOSURE
SARS-CoV-2 detected via nucleic acid testing.
MAIN OUTCOMES AND MEASURES
Post-COVID-19 conditions, defined as any persistent, new, or recurrent health problems reported in the 90-day follow-up survey.
RESULTS
Of 8642 enrolled children, 2368 (27.4%) were SARS-CoV-2 positive, among whom 2365 (99.9%) had index ED visit disposition data available; among the 1884 children (79.7%) who completed follow-up, the median age was 3 years (IQR, 0-10 years) and 994 (52.8%) were boys. A total of 110 SARS-CoV-2-positive children (5.8%; 95% CI, 4.8%-7.0%) reported PCCs, including 44 of 447 children (9.8%; 95% CI, 7.4%-13.0%) hospitalized during the acute illness and 66 of 1437 children (4.6%; 95% CI, 3.6%-5.8%) not hospitalized during the acute illness (difference. 5.3%; 95% CI, 2.5%-8.5%). Among SARS-CoV-2-positive children, the most common symptom was fatigue or weakness (21 [1.1%]). Characteristics associated with reporting at least 1 PCC at 90 days included being hospitalized 48 hours or more compared with no hospitalization (adjusted odds ratio [aOR], 2.67 [95% CI, 1.63-4.38]); having 4 or more symptoms reported at the index ED visit compared with 1 to 3 symptoms (4-6 symptoms: aOR, 2.35 [95% CI, 1.28-4.31]; >= 7 symptoms: aOR, 4.59 [95% CI, 2.50 8.44]); and being 14 years of age or older compared with younger than 1 year (aOR, 2.67 [95% CI, 1.43-4.99]). SARS-CoV-2-positive children were more likely to report PCCs at 90 days compared with those who tested negative, both among those who were not hospitalized (55 of 1295 [4.2%; 95% CI, 3.2%-5.5%] vs 35 of 1321[2.7%; 95% CI, 1.9%-3.7%]; difference, 1.6% [95% CI, 0.2%-3.0%]) and those who were hospitalized (40 of 391[10.2%; 95% CI, 7.4%-13.7%] vs 19 of 380 [5.0%; 95% CI, 3.0%-7.7%]; difference, 5.2% [95% CI, 1.5%-9.1%]). In addition, SARS-CoV-2 positivity was associated with reporting PCCs 90 days after the index ED visit (aOR, 1.63 [95% CI, 1.14-2.35]), specifically systemic health problems (eg, fatigue, weakness, fever; aOR, 2.44 [95% CI, 1.19-5.00]).
CONCLUSIONS AND RELEVANCE
In this cohort study, SARS-CoV-2 infection was associated with reporting PCCs at 90 days in children. Guidance and follow-up are particularly necessary for hospitalized children who have numerous acute symptoms and are older.This studywas supported by grants from the Canadian Institutes of Health Research (operating grant: COVID-19-clinical management); the Alberta Health Services-University of Calgary-Clinical Research Fund; the Alberta Children's Hospital Research Institute; the COVID-19 Research Accelerator Funding Track (CRAFT) Program at the University of California, Davis; and the Cincinnati Children's Hospital Medical Center Division of Emergency Medicine Small Grants Program. Dr Funk is supported by the University of Calgary Eyes-High PostDoctoral Research Fund. Dr Freedman is supported by the Alberta Children's Hospital Foundation Professorship in Child Health andWellness
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