Stepsize control for Newton's method in the presence of singularities

Singularities in the Jacobian matrix are an obstacle to Newton's method. We show that stepsize controls suggested by Deuflhard and Steinhoff can be used to detect and rapidly converge to such singularities.Comment: 14 pages, 4 figure

Colorectal Cancer Screening Quality Improvement: A FITKit Mailing Initiative

According to the American Cancer Society, colorectal cancers are diagnosed in 1 in 22 men and 1 in 24 women in their lifetime. Despite the wide range of effective CRC screening options available in the US, the Hudson Headwaters Health Network (HHHN) has seen little improvement in its CRC screening rates of approximately 60-63% in recent years. This places HHHN, an FQHC in Upstate New York, well below the National Colorectal Cancer Round Table 2018 goal of 80% screening in eligible, average-risk adults. This quality improvement project sought to improve HHHN’s CRC screening rates through a new FITKit direct-mailing initiative. A literature search was conducted, informing the design of a pilot mailing initiative based on recent studies of direct-mailing FITKit outreach in comparable FQHC’s and safety net institutions. In mid-January, 2019, FITKits with return address labels and postage were mailed to 362 HHHN patients’ homes. The cohort represented a population that was age 50-75, currently failing the CRC screening measure, had not seen a PCP in the last calendar year, had BMI ≥ 30, and had 0-5 comorbidities per a network-wide EMR data search in December, 2018. These mailings were preceded by an introductory email and included a second introductory letter along with the network’s usual ‘FITKit Facts and FAQ’s’ sheet. Mailings were followed by two or more automated phone reminders to complete the screening. Only one month after mailings were released, the network received 26 completed FITKits for processing, representing a 7.14% early return rate for the initiative.https://scholarworks.uvm.edu/fmclerk/1505/thumbnail.jp

Interplay of growth mode and thermally induced spin accumulation in epitaxial Al/Co2_2TiSi/Al and Al/Co2_2TiGe/Al contacts

The feasibility of thermally driven spin injectors built from half-metallic Heusler alloys inserted between aluminum leads was investigated by means of {\em ab initio} calculations of the thermodynamic equilibrium and electronic transport. We have focused on two main issues and found that: (i) the interface between Al and the closely lattice-matched Heusler alloys of type Co$_2$Ti$Z$ ($Z=$ Si or Ge) is stable under various growth conditions; and (ii) the conventional and spin-dependent Seebeck coefficients in such heterojunctions exhibit a strong dependence on both the spacer and the atomic composition of the Al/Heusler interface. The latter quantity gives a measure of the spin accumulation and varies between $+8$~$\mu$V/K and $-3$~$\mu$V/K near $300$~K, depending on whether a Ti-Ge or a Co-Co plane makes the contact between Al and Co$_2$TiGe in the trilayer. Our results show that it is in principle possible to tailor the spin-caloric effects by a targeted growth control of the samples.Comment: 16 pages, 13 figure

Structural stability, magnetic and electronic properties of Co2MnSi(001)/MgO heterostructures: A density functional theory study

A computational study of the epitaxial Co2MnSi(001)/MgO(001) interface relevant to tunneling magnetoresistive (TMR) devices is presented. Employing ab initio atomistic thermodynamics, we show that the Co- or MnSi-planes of bulk-terminated Co2MnSi form stable interfaces, while pure Si or pure Mn termination requires non-equilibrium conditions. Except for the pure Mn interface, the half-metallic property of bulk Co2MnSi is disrupted by interface bands. Even so, at homogeneous Mn or Co interfaces these bands contribute little to the minority-spin conductance through an MgO barrier, and hence such terminations could perform strongly in TMR devices.Comment: 4 pages, 3 fig