1,373 research outputs found
Treatment utilization and outcomes in elderly patients with locally advanced esophageal carcinoma: A review of the National Cancer Database
For elderly patients with locally advanced esophageal cancer, therapeutic approaches and outcomes in a modern cohort are not well characterized. Patients ≥70 years old with clinical stage II and III esophageal cancer diagnosed between 1998 and 2012 were identified from the National Cancer Database and stratified based on treatment type. Variables associated with treatment utilization were evaluated using logistic regression and survival evaluated using Cox proportional hazards analysis. Propensity matching (1:1) was performed to help account for selection bias. A total of 21,593 patients were identified. Median and maximum ages were 77 and 90, respectively. Treatment included palliative therapy (24.3%), chemoradiation (37.1%), trimodality therapy (10.0%), esophagectomy alone (5.6%), or no therapy (12.9%). Age ≥80 (OR 0.73), female gender (OR 0.81), Charlson-Deyo comorbidity score ≥2 (OR 0.82), and high-volume centers (OR 0.83) were associated with a decreased likelihood of palliative therapy versus no treatment. Age ≥80 (OR 0.79) and Clinical Stage III (OR 0.33) were associated with a decreased likelihood, while adenocarcinoma histology (OR 1.33) and nonacademic cancer centers (OR 3.9), an increased likelihood of esophagectomy alone compared to definitive chemoradiation. Age ≥80 (OR 0.15), female gender (OR 0.80), and non-Caucasian race (OR 0.63) were associated with a decreased likelihood, while adenocarcinoma histology (OR 2.10) and high-volume centers (OR 2.34), an increased likelihood of trimodality therapy compared to definitive chemoradiation. Each treatment type demonstrated improved survival compared to no therapy: palliative treatment (HR 0.49) to trimodality therapy (HR 0.25) with significance between all groups. Any therapy, including palliative care, was associated with improved survival; however, subsets of elderly patients with locally advanced esophageal cancer are less likely to receive aggressive therapy. Care should be taken to not unnecessarily deprive these individuals of treatment that may improve survival
Acoustic Energy and Momentum in a Moving Medium
By exploiting the mathematical analogy between the propagation of sound in a
non-homogeneous potential flow and the propagation of a scalar field in a
background gravitational field, various wave ``energy'' and wave ``momentum''
conservation laws are established in a systematic manner. In particular the
acoustic energy conservation law due to Blokhintsev appears as the result of
the conservation of a mixed co- and contravariant energy-momentum tensor, while
the exchange of relative energy between the wave and the mean flow mediated by
the radiation stress tensor, first noted by Longuet-Higgins and Stewart in the
context of ocean waves, appears as the covariant conservation of the doubly
contravariant form of the same energy-momentum tensor.Comment: 25 Pages, Late
Trade Implications of the Food Security Act of 1985
One of the central themes of the Food Security Act of 1985 (FSA85) is to make the United States more competitive in exporting agricultural commodities. The means to achieve this objective include lower loan rates, marketing loan provisions, and export credits and subsidies. The comprehensive analysis of the FSA85 (Womack et. al.) has taken these programs into account in making estimates of U.S. prices, exports and other performance variables. The purpose of this paper is to focus attention on the foreign import demand and competitor supplies that underlie the U.S. export estimates and to evaluate the responsiveness of trade patterns to the changes in U.S. policies
GREAT3 results I: systematic errors in shear estimation and the impact of real galaxy morphology
We present first results from the third GRavitational lEnsing Accuracy
Testing (GREAT3) challenge, the third in a sequence of challenges for testing
methods of inferring weak gravitational lensing shear distortions from
simulated galaxy images. GREAT3 was divided into experiments to test three
specific questions, and included simulated space- and ground-based data with
constant or cosmologically-varying shear fields. The simplest (control)
experiment included parametric galaxies with a realistic distribution of
signal-to-noise, size, and ellipticity, and a complex point spread function
(PSF). The other experiments tested the additional impact of realistic galaxy
morphology, multiple exposure imaging, and the uncertainty about a
spatially-varying PSF; the last two questions will be explored in Paper II. The
24 participating teams competed to estimate lensing shears to within systematic
error tolerances for upcoming Stage-IV dark energy surveys, making 1525
submissions overall. GREAT3 saw considerable variety and innovation in the
types of methods applied. Several teams now meet or exceed the targets in many
of the tests conducted (to within the statistical errors). We conclude that the
presence of realistic galaxy morphology in simulations changes shear
calibration biases by per cent for a wide range of methods. Other
effects such as truncation biases due to finite galaxy postage stamps, and the
impact of galaxy type as measured by the S\'{e}rsic index, are quantified for
the first time. Our results generalize previous studies regarding sensitivities
to galaxy size and signal-to-noise, and to PSF properties such as seeing and
defocus. Almost all methods' results support the simple model in which additive
shear biases depend linearly on PSF ellipticity.Comment: 32 pages + 15 pages of technical appendices; 28 figures; submitted to
MNRAS; latest version has minor updates in presentation of 4 figures, no
changes in content or conclusion
Financing Direct Democracy: Revisiting the Research on Campaign Spending and Citizen Initiatives
The conventional view in the direct democracy literature is that spending against a measure is more effective than spending in favor of a measure, but the empirical results underlying this conclusion have been questioned by recent research. We argue that the conventional finding is driven by the endogenous nature of campaign spending: initiative proponents spend more when their ballot measure is likely to fail. We address this endogeneity by using an instrumental variables approach to analyze a comprehensive dataset of ballot propositions in California from 1976 to 2004. We find that both support and opposition spending on citizen initiatives have strong, statistically significant, and countervailing effects. We confirm this finding by looking at time series data from early polling on a subset of these measures. Both analyses show that spending in favor of citizen initiatives substantially increases their chances of passage, just as opposition spending decreases this likelihood
The World Feed-Grains Trade Model: Specification, Estimation, and Validation
The feed-grains trade model is one of the three models in the world trade modeling system developed, updated, and maintained by the Center for Agricultural and Rural Development (CARD). The other two commodity trade models are for wheat and the soybeans complex. The three world models are related through cross-price linkages in the supply and demand components of these models, yet each model can be solved independently. In general, however, all three trade models are solved iteratively to obtain a simultaneous solution. Equilibrium prices, quantities of supply and demand, and net trade are determined by equating excess demands and supplies across regions and explicitly linking prices in each region to a world reference price
FAPRI Trade Model for the Soybean Sector: Specification, Estimation, and Validation
The international components and the overall structure of this model are based on recent work by Huyser (1983). The U.S. Structure and components of the model are based on recent work by Ash (1984) and earlier work by Baumes and Meyers (1980) and Meyers and Hacklander (1979). The roots of all these models trace back to the seminal work on the soybean industry by Houck, Ryan, and Subotnik (1972). A review of related modeling work in the soybean sector can be found in Huyser and Ash
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