Using bootstrap to assess uncertainties of VLBI results I. The method and image-based errors

Very Long Baseline Interferometric (VLBI) observations of quasar jets enable one to measure many theoretically expected effects. Estimating the significance of observational findings is complicated by the correlated noise in the image plane. A reliable and well justified approach to estimate the uncertainties of VLBI results is needed as well as significance testing criteria. We propose to use bootstrap for both tasks. Using simulations we find that bootstrap-based errors for the full intensity, rotation measure, and spectral index maps have coverage closer to the nominal values than conventionally obtained errors. The proposed method naturally takes into account heterogeneous interferometric arrays (such as Space VLBI) and can be easily extended to account for instrumental calibration factors.Comment: Accepted for publication in MNRAS. 11 pages, 16 figure

Zero-Parity Stabbing Information

Everett et al. introduced several varieties of stabbing information for the lines determined by pairs of vertices of a simple polygon P, and established their relationships to vertex visibility and other combinatorial data. In the same spirit, we define the ``zero-parity (ZP) stabbing information'' to be a natural weakening of their ``weak stabbing information,'' retaining only the distinction among {zero, odd, even>0} in the number of polygon edges stabbed. Whereas the weak stabbing information's relation to visibility remains an open problem, we completely settle the analogous questions for zero-parity information, with three results: (1) ZP information is insufficient to distinguish internal from external visibility graph edges; (2) but it does suffice for all polygons that avoid a certain complex substructure; and (3) the natural generalization of ZP information to the continuous case of smooth curves does distinguish internal from external visibility

Getting sick and paying for it

In certain situations, Americans who become chronically ill have to pay higher rates to continue their health insurance coverage. Indeed, although the majority of Americans are insured, hardly anyone is fully protected against the risk that their next insurance policy will cost considerably more than their current one.Insurance, Health

Quantitative Analysis of Health Insurance Reform: Separating Community Rating from Income Redistribution

Two key components of the upcoming health reform are a reorganization of the individual health insurance market and an increase in income redistribution in the economy. Which component contributes more to the welfare outcome of the reform? We address this question by constructing a general equilibrium life cycle model that incorporates both medical expenses and labor income risks. We replicate the key features of the current health insurance system in the U.S. and calibrate the model using the Medical Expenditures Panel Survey dataset. We find that the reform decreases the number of uninsured more than four times. It also brings significant welfare gains equivalent to almost one percent of the annual consumption. However, these welfare gains mostly come from the redistributive measures embedded in the reform. If the reform only reorganizes the individual market, introduces individual mandates but does not include any income-based transfers, the welfare gains are much smaller. This result is mostly driven by the fact that most uninsured people have low income. High burdens of health insurance premiums for this group are relieved disproportionately more by income-based measures than by the new rules in the individual market.health insurance, health reform, risk sharing, general equilibrium

Accounting for non-annuitization

Why don't people buy annuities? Several explanations have been provided by the previous literature: large fraction of preannuitized wealth in retirees' portfolios; adverse selection; bequest motives; and medical expense uncertainty. This paper uses a quantitative model to assess the importance of these impediments to annuitization and also studies three newer explanations: government safety net in terms of means-tested transfers; illiquidity of housing wealth; and restrictions on minimum amount of investment in annuities. This paper shows that quantitatively the last three explanations play a big role in reducing annuity demand. The minimum consumption floor turns out to be important to explain the lack of annuitization, especially for people in lower income quintiles, who are well insured by this provision. The minimum annuity purchase requirement involves big upfront investment and is binding for many, especially if housing wealth cannot be easily annuitized. Among the traditional explanations, preannuitized wealth has the largest quantitative contribution to the annuity puzzle.Accounting

Influence of physic-mechanical properties on a choice of metallurgical slags processing technology

Проаналізовано фізико-механічні властивості шлаків після первинної переробки – тер-мічного (термоудар) і механічного впливу на розплав, схильність відвальних шлаків до розпаду – структурним перетворенням, і можливі види механічної переробки для отримання різних видів шлакової продукції. Наводиться технологічна схема переробки відвальних шлаків (можливе застосування також і для шлаків поточного випуску) з витяганням металу і отриманням широкого спектру шлакової продукції, включаючи в'яжучі матеріали.Проанализированы физико-механические свойства шлаков после первичной переработки – термического (термоудар) и механического воздействия на расплав, склонность отвальных шлаков к распаду – структурным превращениям, и возможные виды механической переработки для получения разных видов шлаковой продукции. Приводится технологическая схема переработки отвальных шлаков (применимо и для шлаков текущего выпуска) с извлечением металла и получением широкого спектра шлаковой продукции, включая вяжущие материалы.Physical and mechanical properties of the slag after the initial processing – thermal (thermal shock) and mechanical impact on the melt, the dump slag inclination to disintegration – structural transformations and the possible kinds of mechanical processing to produce different types of slag products were analyzed. Technological scheme of dump slag (it can also be applied to the current release slags) with metal extraction and of slag products wide range, including cementations materials were given

Vulnerable Open Source Dependencies: Counting Those That Matter

BACKGROUND: Vulnerable dependencies are a known problem in today's open-source software ecosystems because OSS libraries are highly interconnected and developers do not always update their dependencies. AIMS: In this paper we aim to present a precise methodology, that combines the code-based analysis of patches with information on build, test, update dates, and group extracted from the very code repository, and therefore, caters to the needs of industrial practice for correct allocation of development and audit resources. METHOD: To understand the industrial impact of the proposed methodology, we considered the 200 most popular OSS Java libraries used by SAP in its own software. Our analysis included 10905 distinct GAVs (group, artifact, version) when considering all the library versions. RESULTS: We found that about 20% of the dependencies affected by a known vulnerability are not deployed, and therefore, they do not represent a danger to the analyzed library because they cannot be exploited in practice. Developers of the analyzed libraries are able to fix (and actually responsible for) 82% of the deployed vulnerable dependencies. The vast majority (81%) of vulnerable dependencies may be fixed by simply updating to a new version, while 1% of the vulnerable dependencies in our sample are halted, and therefore, potentially require a costly mitigation strategy. CONCLUSIONS: Our case study shows that the correct counting allows software development companies to receive actionable information about their library dependencies, and therefore, correctly allocate costly development and audit resources, which is spent inefficiently in case of distorted measurements.Comment: This is a pre-print of the paper that appears, with the same title, in the proceedings of the 12th International Symposium on Empirical Software Engineering and Measurement, 201

The Source of Maser Emission W33C (G12.8-0.2)

Results of observations of the maser sources toward the W33C region (G12.8-0.2) carried out on the 22-m radio telescope of the Pushchino Radio Astronomy Observatory in the 1.35-cm H2O line and on the Large radio telescope in Nancay (France) in the main (1665 and 1667 MHz) and satellite (1612 and 1720 MHz) OH lines are reported. Multiple, strongly variable short-lived H2O emission features were detected in a broad interval of radial velocities, from -7 to 55 km/s. OH maser emission in the 1667-MHz line was discovered in a velocity range of 35-41 km/s. Stokes parameters of maser emission in the main OH lines 1665 and 1667 MHz were measured. Zeeman splitting was detected in the 1665-MHz line at 33.4 and 39.4 km/s and in the 1667 MHz line only at 39.4 km/s. The magnetic field intensity was estimated. A appreciable variability of Zeeman splitting components was observed at 39 and 39.8 km/s in both main lines. The extended spectrum and fast variability of the H2O maser emission together with the variability of the Zeeman splitting components in the main OH lines can be due to the composite clumpy structure of the molecular cloud and to the presence in it of large-scale rotation and bipolar outflow as well as of turbulent motions of material.Comment: 7 pages, 2 tables, 8 figures, accepted by Astronomicheskii Zhurnal (Astronomy Reports

SUBSTANTIATION OF MUD PREPARATION TECHNOLOGY

To study the advantages of hydrodynamic cavitation, to calculate the frequency of cavitation oscillations by the device parameters, to obtain a formula for determining the dispersion time of the material, and to study the flow of the drilling fluid in the device using the SolidWorks program