Essays on radiology services utilization in the United States

This dissertation investigates how policies and financial incentives may affect the use of services within the United States health care system. The research consists of two distinct parts: Part I comprises two studies examining the impact of recently enacted state legislation regarding dense breast tissue on the use of downstream imaging; Part II delves into changes in physician reimbursement and their effect on health care delivery. Dense breast tissue is a common finding that decreases the sensitivity of mammography in detecting cancer. Some states have passed legislation requiring health care providers to notify patients with dense breast tissue that identification of early cancers may be compromised. Others have also aimed to increase access to supplemental screening tests by requiring health plans to include such follow-up options in covered benefits. The legislation has been controversial because supplemental imaging following a negative screening mammogram for patients with no other risk factors provides little benefit compared to its substantial cost. In the first study, we analyzed whether the dense breast tissue notification laws affected the probability of screening mammography follow-up by ultrasound and magnetic resonance imaging (MRI). We found strong evidence that implementing the notification legislation led to an increase in the probability of downstream breast ultrasound imaging in most states, and to an increase in the probability of downstream breast MRI in some states. In the second study, we identified specific characteristics of various state-level dense breast policies that were associated with increased use of downstream breast ultrasound imaging. In Part II of the dissertation, we assessed the extent to which changes in health care prices affect the provision of health services by physicians in various medical and surgical specialties in both Medicare and the private sector. We exploited the considerable changes in the Medicare Physician Fee schedule due to procedural code bundling that happened between 2010 and 2014 as the source of variation in health care prices. Our results showed that volume responses to changes in health care prices are inelastic and vary in both direction and magnitude by specialty and sector.2019-10-31T00:00:00

Advanced Medical Imaging in Privately Insured Patients Recent Trends in Utilization and Payments

Boston University Health Policy Institut

Ab Initio Study of Some Persistent Nitroxide Radicals

Stable free radicals have a variety of applications. Particularly, the aminoxyl group is frequently used in spin-labeling experiments. Nitroxides may also exhibit intriguing chiral and magnetic properties, and can be of interest for studies of molecular parity violation. We present results for three different groups of persistent nitroxide radicals: i) acyclic: dimethylaminoxyl (Me2NO), bis(trifluoromethyl)aminoxyl (CF3)2NO, and di-tert-butyl nitroxyl [(Me3C)2NO]; ii) cyclic: aziridine-N-oxyl, azetidine-N-oxyl, pyrrolidine-N-oxyl and piperidine-N-oxyl; and iii) imino nitroxides. We used density functional and ab initio (MP2, coupled cluster) methods to obtain insight into the underlying chemistry. The molecular structures, harmonic vibrational frequencies, inversion barriers, and hyperfine coupling constants are reported. The cyclic aziridine-N-oxyl exhibits a considerable inversion barrier of ?hc 3500 cm–1 compared to only ?hc 500 cm–1 for the other examples. Stable imino nitroxides are theoretically characterized for the first time in our work. We discuss the possibilities that some of the chiral derivatives may be dominated by molecular parity violation in their dynamics

Generation of attosecond electron bunches and X-ray pulses from few-cycle femtosecond laser pulses

Laser-plasma electron accelerators can be used to produce high-intensity X-rays, as electrons accelerated in wakefields emit radiation due to betatron oscillations.Such X-ray sources inherit the features of the electron beam; sub-femtosecond electron bunches produce betatron sources of the same duration, which in turn allow probing matter on ultrashort time scales. In this paper we show, via Particle-in-Cell simulations, that attosecond electron bunches can be obtained using low-energy, ultra-short laser beams both in the self-injection and the controlled injection regimes at low plasma densities. However, only in the controlled regime does the electron injection lead to a stable, isolated attosecond electron bunch. Such ultrashort electron bunches are shown to emit attosecond X-ray bursts with high brillianceComment: 12 pages, 5 figure

MECHANICAL AND STRUCTURAL PROPERTIES OF COLLAGEN NANOFRIBROUS LAYERS UNDER SIMULATED BODY CONDITIONS

The theme of this paper is the analysis of mechanical and structural properties of nanofibrous COL under simulated body conditions and in the presence of osteoblasts and dermal fibroblasts. COL were prepared by electrostatic spinning of 8wt% collagen type I dispersion with 8wt% (to COL) of PEG in phosphate buffer/ethanol solution (1/1vol). The stability of COL was enhanced by means of cross-linking with EDC and NHS at a molar ratio of 4:1. COL were exposed in culture medium for 21 days and human SAOS-2 human dermal fibroblasts and osteoblasts were cultured therein for 21 days as well. The cell culture on COL was assessed by fluorescence microscopy and metabolic activity. Then the metabolic activity of both cell types grown on COL and PS were measured after 1, 7, 14 and 21 days using the Alamar Blue assay method. Mechanical properties were determined using an tensile test. The influence of the cell activity on secondary structure of COL was verified by IR spectroscopy. Furthermore, the influence of cells on COL was evaluated by SEM

INFLUENCE STRES ON THE TRAINING PROCESS OF THE HORSES

Etological and physiological tests were realized on 48 horses. There were observed following activities: spontaneous kinetic activity, voice display; the elimination behavior (excretion and urination) and motionless standing. The horses were observed in 40 minute periods during the morning hours. The horses were classed into the following groups: EHB+ - crossing more than 220 sq. per 40 min. (high sensitiveness to stress), EHB+/- - crossing 131 - 220 sq. per 40 min. (mean sensitiveness to stress), EHB- - crossing 130 and less sq. per 40 min. (low sensitiveness to stress). After the evaluating of mineral, energetic, lipid, nitrogen, and enzymatic profile of sport horses there were not observed significant differences from the reference values

ANALYSIS OF FAMILIES OF NONIUS BREED IN SLOVAKIA

Cieľom práce bolo uskutočniť analýzu génovej rezervy plemena Nonius z hľadiska uplatnenia jednotlivých rodín v chove tohto plemena na Slovensku. Pri vyhodnocovaní uplatnenia jednotlivých rodín sme hodnotili dĺžku pôsobenia konkrétnej rodiny v chove, počet chovných kobýl v rodine do súčasnosti, počet generácií v rodine do súčasnosti a počet chovných kobýl rodiny zaradených v súčasnosti do génovej rezervy. Ďalej sme porovnávali hodnoty základných telových mier a výsledky skúšok výkonnosti dosiahnuté v konkrétnych rodinách. Z dosiahnutých výsledkov sme zistili, že na Slovensku pôsobí 14 rodín plemena Nonius, v chove bolo zaradených 34 kobýl. Najlepšie hodnotenie mala rodina 597 Nonius XVI-15. Z výsledkov môžeme konštatovať, že úroveň chovu tohto plemena za posledné desaťročie výrazne vzrástla, čím sa odvrátila cesta likvidácie Noniusa na Slovensku.The aim of study was to analyze gene reserve of Nonius breed, from a point of families´ used in breeding in Slovakia. In evaluation of separated families, the length of impact of family in breed, number of breeding mares in family to present, number of generations in family to present and the number of breeding mares inserted to gene reserve was measured. Also the basic body measurements and the results of exams of performance in families were evaluated. From our results it could be concluded that in Slovakia 14 families of breed Nonius are effective and 34 mares are inserted in breeding. The family 597 Nonius XVI - 15 has the best evaluation. From the results, we can state, that the level of this breed has increased in last 10 years. On the other hand, destroy of Nonius was warded off in Slovakia