Calculating quench propagation with ANSYS®

A commercial Finite-Element-Analysis program, ANSYS®, is widely used in structural and thermal analysis. With the program's ability to include nonlinear material properties and import complex CAD files, one can generate coil geometries and simulate quench propagation in superconducting magnets. A "proof-of-principle" finite element model was developed assuming a resistivity that increases linearly from zero to its normal value at a temperature consistent with the assumed B magnetic field. More sophisticated models could easily include finer-grained coil, cable, structural, and circuit details. A quench is provoked by raising the temperature of an arbitrary superconducting element above its T . The time response to this perturbation is calculated using small time-steps to allow convergence between steps. Snapshots of the temperature and voltage distributions allow examination of longitudinal and turn-to-turn quench propagation, quench-front annihilation, and cryo-stability. Modeling details are discussed, and a computed voltage history was compared with measurements from a recent magnet test.

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

The Effect Of Income Taxes On Household Income

Research on the distribution of income during the 1980s has identified a trend towards increasing inequality, which may be the continuation and acceleration of trends spanning several decades. This paper explores to what extent behavioral responses to the tax changes during the 1980s may also explain the rising inequality. The 1986 Tax Reform Act is used as a natural experiment to explore the roles played by both taxes and a variety of nontax factors. Our principal finding is that both tax rates and nontax factors appear to have had significant effects on relative income growth during the late 1980s. © 2000 by the President and Fellows of Harvard College and the Massachusetts Institute of Technology

A superconducting quadrupole magnet array for a heavy ion fusion driver

A multi-channel quadrupole array has been proposed to increase beam intensity and reduce space charge effects in a Heavy Ion Fusion Driver. A single array unit composed of several quadrupole magnets, each with its own beam line, will be placed within a ferromagnetic accelerating core whose cost is directly affected by the array size. A large number of focusing arrays will be needed along the accelerating path. The use of a superconducting quadrupole magnet array will increase the field and reduce overall cost. We report here on the design of a compact 3 x 3 superconducting quadrupole magnet array. The overall array diameter and length including the cryostat is 900 x 700 mm. Each of the 9 quadrupole magnets has a 78 mm warm bore and an operating gradient of 50 T/m over an effective magnetic length of 320 mm

Sampling Techniques for Big Data Analysis

In analysing big data for finite population inference, it is critical to adjust for the selection bias in the big data. In this paper, we propose two methods of reducing the selection bias associated with the big data sample. The first method uses a version of inverse sampling by incorporating auxiliary information from external sources, and the second one borrows the idea of data integration by combining the big data sample with an independent probability sample. Two simulation studies show that the proposed methods are unbiased and have better coverage rates than their alternatives. In addition, the proposed methods are easy to implement in practice.This is a manuscript of an article published as J.K. Kim and Z. Wang (2019). "Sampling Techniques for Big Data Analysis," International Statistical Review, 87, S177-S191. doi: 10.1111/insr.12290. Posted with permission.</p

Use of a rapid electronic survey methodology to estimate blood donors' potential exposure to emerging infectious diseases: Application of a statistically representative sampling methodology to assess risk in US blood centers

UNLABELLED: Risk assessments of transfusion-transmitted emerging infectious diseases (EIDs) are complicated by the fact that blood donors demographics and behaviors can be different from the general population. Therefore, when assessing potential blood donor exposure to EIDs, the use of general population characteristics, such as U.S. travel statistics, may invoke uncertainties that result in inaccurate estimates of blood donor exposure. This may, in turn, lead to the creation of donor deferral policies that do not match actual risk. STUDY DESIGN AND METHODS: This article reports on the development of a system to rapidly assess EID risks for a nationally representative portion of the U.S. blood donor population. To assess the effectiveness of this system, a test survey was developed and deployed to a statistically representative sample frame of blood donors from five blood collecting organizations. Donors were directed to an online survey to ascertain their recent travel and potential exposure to Middle East respiratory syndrome coronavirus (MERS-CoV). RESULTS: A total of 7128 responses were received from 54 256 invitations. The age-adjusted estimated total number of blood donors potentially exposed to MERS-CoV was approximately 15 640 blood donors compared to a lower U.S. general population-based estimate of 9610 blood donors. CONCLUSION: The structured donor demographic sample-based data provided an assessment of blood donors potential exposure to an emerging pathogen that was 63% larger than the U.S. population-based estimate. This illustrates the need for tailored blood donor-based EID risk assessments that provide more specific demographic risk intelligence and can inform appropriate regulatory decision making