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1.
Circulation ; 147(20): 1492-1504, 2023 05 16.
Artículo en Inglés | MEDLINE | ID: mdl-36871212

RESUMEN

BACKGROUND: Self-management education and support (SMES) interventions have modest effects on intermediate outcomes for those at risk of cardiovascular disease, but few studies have measured or demonstrated an effect on clinical end points. Advertising for commercial products is known to influence behavior, but advertising principles are not typically incorporated into SMES design. METHODS: This randomized trial studied the effect of a novel tailored SMES program designed by an advertising firm among a population of older adults with low income at high cardiovascular risk in Alberta, Canada. The intervention included health promotion messaging from a fictitious "peer" and facilitated relay of clinical information to patients' primary care provider and pharmacist. The primary outcome was the composite of death, myocardial infarction, stroke, coronary revascularization, and hospitalizations for cardiovascular-related ambulatory care-sensitive conditions. Rates of the primary outcome and its components were compared using negative binomial regression. Secondary outcomes included quality of life (EQ-5D [EuroQoL 5-dimension] index score), medication adherence, and overall health care costs. RESULTS: We randomized 4761 individuals, with a mean age of 74.4 years, of whom 46.8% were female. There was no evidence of statistical interaction (P=0.99) or of a synergistic effect between the 2 interventions in the factorial trial with respect to the primary outcome, which allowed us to evaluate the effect of each intervention separately. Over a median follow-up time of 36 months, the rate of the primary outcome was lower in the group that received SMES compared with the control group (incidence rate ratio, 0.78 [95% CI, 0.61 to 1.00]; P=0.047). No significant between-group changes in quality of life over time were observed (mean difference, 0.0001 [95% CI, -0.018 to 0.018]; P=0.99). The proportion of participants who were adherent to medications was not different between the 2 groups (P=0.199 for statins and P=0.754 for angiotensin-converting enzyme inhibitors/angiotensin receptor blockers). Overall adjusted health care costs did not differ between those receiving SMES and the control group ($2015 [95% CI, -$1953 to $5985]; P=0.320). CONCLUSIONS: For older adults with low income, a tailored SMES program using advertising principles reduced the rate of clinical outcomes compared with usual care. The mechanisms of improvement are unclear and further studies are required. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02579655.


Asunto(s)
Enfermedades Cardiovasculares , Automanejo , Humanos , Femenino , Anciano , Masculino , Enfermedades Cardiovasculares/epidemiología , Enfermedades Cardiovasculares/prevención & control , Calidad de Vida , Publicidad , Factores de Riesgo , Factores de Riesgo de Enfermedad Cardiaca , Alberta
2.
Circulation ; 147(20): 1505-1514, 2023 05 16.
Artículo en Inglés | MEDLINE | ID: mdl-36871215

RESUMEN

BACKGROUND: One in eight people with heart disease has poor medication adherence that, in part, is related to copayment costs. This study tested whether eliminating copayments for high-value medications among low-income older adults at high cardiovascular risk would improve clinical outcomes. METHODS: This randomized 2×2 factorial trial studied 2 distinct interventions in Alberta, Canada: eliminating copayments for high-value preventive medications and a self-management education and support program (reported separately). The findings for the first intervention, which waived the usual 30% copayment on 15 medication classes commonly used to reduce cardiovascular events, compared with usual copayment, is reported here. The primary outcome was the composite of death, myocardial infarction, stroke, coronary revascularization, and cardiovascular-related hospitalizations over a 3-year follow-up. Rates of the primary outcome and its components were compared using negative binomial regression. Secondary outcomes included quality of life (Euroqol 5-dimension index score), medication adherence, and overall health care costs. RESULTS: A total of 4761 individuals were randomized and followed for a median of 36 months. There was no evidence of statistical interaction (P=0.99) or of a synergistic effect between the 2 interventions in the factorial trial with respect to the primary outcome, which allowed us to evaluate the effect of each intervention separately. The rate of the primary outcome was not reduced by copayment elimination, (521 versus 533 events, incidence rate ratio 0.84 [95% CI, 0.66-1.07], P=0.162). The incidence rate ratio for nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death (0.97 [95% CI, 0.67-1.39]), death (0.94 [95% CI, 0.80 to 1.11]), and cardiovascular-related hospitalizations (0.78 [95% CI, 0.57 to 1.06]) did not differ between groups. No significant between-group changes in quality of life over time were observed (mean difference, 0.012 [95% CI, -0.006 to 0.030], P=0.19). The proportion of participants who were adherent to statins was 0.72 versus 0.69 for the copayment elimination versus usual copayment groups, respectively (mean difference, 0.03 [95% CI, 0.006-0.06], P=0.016). Overall adjusted health care costs did not differ ($3575 [95% CI, -605 to 7168], P=0.098). CONCLUSIONS: In low-income adults at high cardiovascular risk, eliminating copayments (average, $35/mo) did not improve clinical outcomes or reduce health care costs, despite a modest improvement in adherence to medications. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02579655.


Asunto(s)
Enfermedades Cardiovasculares , Infarto del Miocardio , Accidente Cerebrovascular , Humanos , Anciano , Enfermedades Cardiovasculares/tratamiento farmacológico , Enfermedades Cardiovasculares/epidemiología , Enfermedades Cardiovasculares/prevención & control , Calidad de Vida , Factores de Riesgo , Infarto del Miocardio/tratamiento farmacológico , Infarto del Miocardio/epidemiología , Infarto del Miocardio/prevención & control , Accidente Cerebrovascular/epidemiología , Accidente Cerebrovascular/prevención & control , Alberta
3.
Phys Rev Lett ; 111(5): 054801, 2013 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-23952409

RESUMEN

The microbunching instability driven by collective effects of the beam inside an accelerator can significantly degrade the final electron beam quality for free electron laser (FEL) radiation. In this Letter, we propose an inexpensive scheme to suppress such an instability in accelerators for next generation FEL light sources. Instead of using an expensive device such as a laser heater or RF deflecting cavities, this scheme uses longitudinal mixing associated with the transverse spread of the beam through bending magnets inside the accelerator transport system to suppress the instability. The final uncorrelated energy spread increases roughly by the current compression factor, which is important in seeded FEL schemes in order to achieve high harmonic short-wavelength x-ray radiation.


Asunto(s)
Electrones , Rayos Láser , Imanes/química , Modelos Teóricos
4.
Phys Rev E ; 106(6-2): 065302, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36671143

RESUMEN

Measures of discrepancy between probability distributions (statistical distance) are widely used in the fields of artificial intelligence and machine learning. We describe how certain measures of statistical distance can be implemented as numerical diagnostics for simulations involving charged-particle beams. Related measures of statistical dependence are also described. The resulting diagnostics provide sensitive measures of dynamical processes important for beams in nonlinear or high-intensity systems, which are otherwise difficult to characterize. The focus is on kernel-based methods such as maximum mean discrepancy, which have a well-developed mathematical foundation and reasonable computational complexity. Several benchmark problems and examples involving intense beams are discussed. While the focus is on charged-particle beams, these methods may also be applied to other many-body systems such as plasmas or gravitational systems.


Asunto(s)
Inteligencia Artificial , Simulación por Computador
5.
Phys Rev E ; 103(6-1): 062216, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-34271647

RESUMEN

Integrable dynamical systems play an important role in many areas of science, including accelerator and plasma physics. An integrable dynamical system with n degrees of freedom possesses n nontrivial integrals of motion, and can be solved, in principle, by covering the phase space with one or more charts in which the dynamics can be described using action-angle coordinates. To obtain the frequencies of motion, both the transformation to action-angle coordinates and its inverse must be known in explicit form. However, no general algorithm exists for constructing this transformation explicitly from a set of n known (and generally coupled) integrals of motion. In this paper we describe how one can determine the dynamical frequencies of the motion as functions of these n integrals in the absence of explicitly known action-angle variables, and we provide several examples.

6.
Phys Rev E ; 100(5-1): 053308, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31869885

RESUMEN

A numerical method is described for producing stationary solutions of the Vlasov-Poisson system describing a relativistic charged-particle beam in a constant focusing accelerator channel, confined transversely by a general (linear or nonlinear) focusing potential. The method utilizes a variant of the spectral Galerkin algorithm to solve a nonlinear partial differential equation (PDE) in two degrees of freedom for the beam space charge potential in equilibrium. Numerical convergence with an increasing number of computed spectral modes is investigated for several benchmark problems. Preservation of the stationary phase space density is verified using a strongly nonlinear focusing channel based on the Integrable Optics Test Accelerator at Fermi National Accelerator Laboratory.

7.
Radiat Meas ; 42(6-7): 1075-1084, 2007 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-18591988

RESUMEN

As a result of terrorism, accident, or war, populations potentially can be exposed to doses of ionizing radiation that could cause direct clinical effects within days or weeks. There is a critical need to determine the magnitude of the exposure to individuals so that those with significant risk have appropriate procedures initiated immediately, while those without a significant probability of acute effects can be reassured and removed from the need for further consideration in the medical/emergency system. In many of the plausible scenarios there is an urgent need to make the determination very soon after the event and while the subject is still present. In vivo EPR measurements of radiation-induced changes in the enamel of teeth is a method, perhaps the only such method, which can differentiate among doses sufficiently for classifying individuals into categories for treatment with sufficient accuracy to facilitate decisions on medical treatment. In its current state, the in vivo EPR dosimeter can provide estimates of absorbed dose with an error approximately +/- 50 cGy over the range of interest for acute biological effects of radiation, assuming repeated measurements of the tooth in the mouth of the subject. The time required for acquisition, the lower limit, and the precision are expected to improve, with improvements in the resonator and the algorithm for acquiring and calculating the dose. The magnet system that is currently used, while potentially deployable, is somewhat large and heavy, requiring that it be mounted on a small truck or trailer. Several smaller magnets, including an intraoral magnet are under development, which would extend the ease of use of this technique.

8.
Implement Sci ; 11(1): 131, 2016 Sep 26.
Artículo en Inglés | MEDLINE | ID: mdl-27671037

RESUMEN

BACKGROUND: Chronic diseases result in significant morbidity and costs. Although medications and lifestyle changes are effective for improving outcomes in chronic diseases, many patients do not receive these treatments, in part because of financial barriers, patient and provider-level knowledge gaps, and low patient motivation. The Assessing outcomes of enhanced chronic disease care through patient education and a value-based formulary study (ACCESS) will determine the impact of two interventions: (1) a value-based formulary which eliminates copayment for high-value preventive medications; and (2) a comprehensive self-management support program aimed at promoting health behavior change and medication adherence, combined with relay of information on medication use to healthcare providers, on cardiovascular events and/or mortality in low-income seniors with elevated cardiovascular risk. METHODS: The ACCESS study will use a parallel, open label, factorial randomized trial design, with blinded endpoint evaluation in 4714 participants who are over age >65 (and therefore have drug insurance provided by Alberta Blue Cross with 30 % co-payment); are at a high risk for cardiovascular events based on a history of any one of the following: coronary heart disease, prior stroke, chronic kidney disease, heart failure, or any two of the following: current cigarette smoking, diabetes mellitus, hypertension, or hypercholesterolemia; and have a household income

9.
Radiat Prot Dosimetry ; 157(4): 536-42, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23864642

RESUMEN

A straightforward method is presented to estimate peak skin doses (PSDs) delivered by computed tomography (CT) scanners. The measured PSD values are related to the well-known volume CT dose index (CTDI(vol)), displayed on the console of CT scanners. PSD measurement estimates were obtained, in four CT units, by placing radiochromic film on the surface of a CTDI head phantom. Six different X-ray tube currents including the maximum allowed value were used to irradiate the phantom. PSD and CTDI(vol) were independently measured and later related to the CTDI(vol) value displayed on the console. A scanner-specific relationship was found between the measured PSD and the associated CTDI(vol) displayed on the console. The measured PSD values varied between 27 and 136 mGy among all scanners when the routine head scan parameters were used. The results of this work allow relating the widely used CTDI(vol) to an actual radiation dose delivered to the skin of a patient.


Asunto(s)
Cabeza/diagnóstico por imagen , Fantasmas de Imagen , Piel/diagnóstico por imagen , Piel/efectos de la radiación , Tomografía Computarizada por Rayos X , Calibración , Dosimetría por Película , Humanos , Iones , Método de Montecarlo , Dosis de Radiación , Reproducibilidad de los Resultados , Tomógrafos Computarizados por Rayos X , Rayos X
10.
NMR Biomed ; 20(1): 58-68, 2007 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-17006885

RESUMEN

In this work, numerical and experimental studies of the transverse electromagnetic (TEM) resonator modes at ultrahigh-field (UHF) MRI are performed using an in-house finite difference time domain package at 340 MHz and using an 8 T whole-body MRI system. The simulations utilized anatomically detailed human head mesh and a spherical head-sized phantom, while the experiments included an electromagnetically equivalent (to simulations) phantom and in vivo human head studies. An in-depth look at the homogeneity of the transmit-and-receive fields and local and global polarization of the electromagnetic waves inside the cavity of the head coil, and also the current distribution obtained on the resonator elements, is provided for several coil modes when the coil is empty and loaded. Based on the numerical and experimental results, which are in excellent agreement, an electromagnetic characterization of loading radio-frequency (RF) head coils during a UHF MRI experiment is provided. The possibility of using the aforementioned modes for specific types of imaging application is briefly reviewed.


Asunto(s)
Imagen por Resonancia Magnética/métodos , Campos Electromagnéticos , Diseño de Equipo , Cabeza/anatomía & histología , Humanos , Imagen por Resonancia Magnética/instrumentación , Fantasmas de Imagen , Ondas de Radio
11.
J Digit Imaging ; 20(1): 42-52, 2007 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17191103

RESUMEN

An acceptable mammography film digitizer must provide high-quality images at a level of diagnostic accuracy comparable to reading conventional film examinations. The purpose of this study was to determine if there are significant differences between the interpretations of conventional film-screen mammography examinations and soft copy readings of the images produced by a mammography film digitizer. Eight radiologists interpreted 120 mammography examinations, half as original films and the other half as digital images on a soft copy work station. No radiologist read the same examination twice. The interpretations were recorded in accordance with the Breast Imaging Reporting and Data System and included other variables such as perceived image quality and diagnostic difficulty and confidence. The results provide support for the hypothesis that there are no significant differences between the interpretations of conventional film-screen mammography examinations and soft copy examinations produced by a mammography film digitizer.


Asunto(s)
Neoplasias de la Mama/diagnóstico por imagen , Presentación de Datos , Mamografía/métodos , Interpretación de Imagen Radiográfica Asistida por Computador , Neoplasias de la Mama/diagnóstico , Toma de Decisiones , Femenino , Humanos , Mamografía/normas , Variaciones Dependientes del Observador , Curva ROC , Estados Unidos
12.
Magn Reson Med ; 54(3): 683-90, 2005 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16088934

RESUMEN

In this work experimental and numerical studies of the MR signal were performed at frequencies ranging from 64 MHz to 485 MHz, utilizing three different MRI coils: a single-strut transverse electromagnetic (TEM)-based coil, a TEM resonator, and a high-pass birdcage coil. The experimental analyses were conducted using 1.5 and 8 Tesla whole-body systems and volume RF head coils. The simulation data were obtained utilizing an in-house-developed finite difference time domain (FDTD) model. Pertinent data from the numerical and experimental setups were compared, and a remarkable agreement between the two methods was found that clearly demonstrates the effectiveness of the FDTD method when it is applied rigorously. The numerical and experimental studies demonstrate the complexity of the electromagnetic (EM) fields and their role in the MR signal. These studies also reveal unique similarities and differences between the transmit and receive field distributions at various field strengths. Finally, for ultra high-field operations, it was demonstrated mathematically, numerically, and experimentally that highly asymmetric inhomogeneous images can be acquired even for linear excitation, symmetrical load geometries, and symmetrical load positioning within the coil.


Asunto(s)
Campos Electromagnéticos , Imagen por Resonancia Magnética/instrumentación , Procesamiento de Señales Asistido por Computador , Diseño de Equipo , Humanos , Fantasmas de Imagen , Ondas de Radio
13.
CMAJ ; 171(1): 39-43, 2004 Jul 06.
Artículo en Inglés | MEDLINE | ID: mdl-15238494

RESUMEN

BACKGROUND: Public insurance for testing supplies for self-monitoring of blood glucose is highly variable across Canada. We sought to determine if insured patients were more likely than uninsured patients to use self-monitoring and whether they had better glycemic control. METHODS: We used baseline survey and laboratory data from patients enrolled in a randomized controlled trial examining the effect of paying for testing supplies on glycemic control. We recruited patients through community pharmacies in Alberta and Saskatchewan from Nov. 2001 to June 2003. To avoid concerns regarding differences in provincial coverage of self-monitoring and medications, we report the analysis of Alberta patients only. RESULTS: Among our sample of 405 patients, 41% had private or public insurance coverage for self-monitoring testing supplies. Patients with insurance had significantly lower hemoglobin A(1c) concentrations than those without insurance coverage (7.1% v. 7.4%, p = 0.03). Patients with insurance were younger, had a higher income, were less likely to have a high school education and were less likely to be married or living with a partner. In multivariate analyses that controlled for these and other potential confounders, lack of insurance coverage for self-monitoring testing supplies was still significantly associated with higher hemoglobin A(1c) concentrations (adjusted difference 0.5%, p = 0.006). INTERPRETATION: Patients without insurance for self-monitoring test strips had poorer glycemic control.


Asunto(s)
Automonitorización de la Glucosa Sanguínea/economía , Diabetes Mellitus Tipo 2/sangre , Cobertura del Seguro , Seguro de Salud , Cooperación del Paciente , Anciano , Alberta , Estudios Transversales , Diabetes Mellitus Tipo 2/economía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Tiras Reactivas/economía , Análisis de Regresión
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