198 research outputs found

    Two Trees: Asset Price Dynamics Induced by Market Clearing

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    If stocks go up, investors may want to rebalance their portfolios. But investors cannot all rebalance. Expected returns may need to change so that the average investor is still happy to hold the market portfolio despite its changed composition. In this way, simple market clearing can give rise to complex asset market dynamics. We study this phenomenon in a very simple model. Our model has two Lucas trees.' Each tree has i.i.d.dividend growth, and the representative investor has log utility. We are able to give analytical solutions to the model. Despite this simple setup, price-dividend ratios, expected returns, and return variances vary through time. A dividend shock leads to underreaction' in some states, as expected returns rise and prices slowly adjust, and overreaction' in others. Expected returns and excess returns are predictable by price-dividend ratios in the time series and in the cross section, roughly matching value effects and return forecasting regressions. Returns generally display positive serial correlation and negative cross-serial correlation, leading to 'momentuem,' but the opposite signs are possible as well. A shock to one asset's dividend a.ects the price and expected return of the other asset, leading to substantial correlation of returns even when there is no correlation of cash flows and giving the appearance of contagion.' Market clearing allows the inverse portfolio' problem to be solved, in which the weights of the assets in the market portfolio are inverted' to solve for the parameters of the assets' return generating process.

    International Risk Sharing is Better Than You Think (or Exchange Rates are Much Too Smooth)

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    Exchange rates depreciate by the difference between the domestic and foreign marginal utility growths. Exchange rates vary a lot , as much as 10% per year. However, equity premia imply that marginal utility growths vary much more, by at least 50% per year. This means that marginal utility growths must be highly correlated across countries -- international risk sharing is better than you think. Conversely, if risks really are not shared internationally, exchange rates should vary more than they do -- exchange rates are much too smooth. We calculate an index of international risk sharing that formalizes this intuition in the context of both complete and incomplete capital markets. Our results suggest that risk sharing is indeed very high across several pairs of countries.

    Impact of Combined Exercise on Chronic Obstructive Pulmonary Patients' State of Health

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    AIM: The aim of the study was to evaluate the effectiveness of a 10-week combined training programme (aerobic and strength exercise) compared to an aerobic training programme, and respiratory physiotherapy on COPD patients' health. METHODS: Fifty subjects with moderate to severe COPD were randomly assigned to two groups. Combined group (CG, n=25) who underwent combined training, and aerobic group (AG, n=25) who underwent aerobic training. These were compared with fifty COPD subjects who underwent respiratory physiotherapy, breathing control and bronchial clearance techniques (RP group, n = 50). We evaluated health state through two questionnaires, St. George's Respiratory Questionnaire (SGRQ) and SF-36, at the beginning and at the end of the programme. RESULTS: The CG group showed differences (p<0.0001) in modification rates in state of health compared to the AG and RP groups in the activity (64 ± 9%, 19 ± 7%, 1 ± 15%) , impact (35 ± 5%, 20 ± 18%, 1 ± 14%) and total (41 ± 9%, 26 ± 17%, 1 ± 15%) domains assessed by the SGRQ, and the physical function (109 ± 74%, 22 ± 12%, 0.1 ± 18%), physical role (52 ± 36%, 11 ± 15%, 1.3 ± 21%) and vitality (83 ± 39%, 14 ± 38%) domains assessed by SF-36. CONCLUSION: These results suggest that combined training in subjects with COPD appears to be a more effective method, with better clinical changes, and improvements in health state perception

    Atividade FĂ­sica e ExercĂ­cio FĂ­sico: Especificidades no Doente CardĂ­aco

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    A atividade fĂ­sica Ă© atualmente um comportamento de grande importĂąncia para a promoção de um estilo de vida saudĂĄvel, contudo vĂĄrios estudos tĂȘm demonstrado elevada prevalĂȘncia de inatividade e comportamentos sedentĂĄrios nas pessoas com doença cardiovascular. Uma prĂĄtica regular de atividade fĂ­sica e de exercĂ­cio fĂ­sico em nĂ­veis adequados assegura diversos benefĂ­cios para a pessoa com doença cardiovascular. Programas de reabilitação cardĂ­aca e de prevenção secundĂĄria tĂȘm como um dos principais objetivos o incentivo Ă  adoção de estilos de vida mais ativos. Neste artigo de revisĂŁo, os conceitos e recomendaçÔes sobre a atividade fĂ­sica e o exercĂ­cio fĂ­sico estruturado em pessoas com doença cardiovascular, vĂŁo ser abordados

    A Post Hoc Analysis on Rhythm and High Intensity Interval Training in Cardiac Resynchronization Therapy

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    Objectives. Evaluate the effects of a 6-month High Intensity Interval Training (HIIT) program on (1) functional capacity and health-related quality of life, (2) multiple blood biomarkers, (3) echocardiographic parameters, and (4) exercise performance, in patients in cardiac resynchronization therapy (CRT) stratified by the presence of atrial fibrillation (AF), targeting the following questions: (1) Does CRT provide similar benefits in patients in AF and sinus rhythm (SR)?; and (2) Does HIIT provides similar benefits in patients in AF and SR? Design. Estimates were available at baseline and 6 months after CRT implantation in 37 patients with heart failure. Patients were randomized after CRT to a 24-week HIIT group or to a usual care group (CON). In this sub-analysis, HIIT (AF = 7; SR = 11) and CON (AF = 9; SR = 10) were stratified by the presence of AF. Results. Patients in AF benefitted to a lesser degree from CRT in functional status than patients in SR (23.8-46.0%). However, HIIT induced superior improvements in patients in AF compared to CON (23.9-61.0%). Decreases in TNF-α (8.5-42.9%), BNP (15.3-34.6%) and left ventricular mass (9.6-26.2%) were only observed in patients in SR, whereas increases in peak oxygen uptake were only observed in patients in AF (19.5-23.2%). HIIT improved exercise capacity (8.8-59.4%) in patients in SR. Conclusions. Patients in AF or SR undergoing CRT demonstrated distinct benefits from device implantation and from HIIT as an adjunctive therapeutic strategy. This suggests that both mainstay and adjunctive therapeutics may need to be managed differently in patients in AF and SR.info:eu-repo/semantics/publishedVersio

    High-Intensity Interval Training in Cardiac Resynchronization Therapy: a Randomized Control Trial

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    AIMS: To determine the effects of high-intensity interval training (HIIT) following cardiac resynchronization therapy (CRT) implantation in patients with chronic heart failure (CHF), on noninvasive estimates of systolic ventricular function, exercise performance, severity of symptoms and quality of life. METHODS: Cardiopulmonary exercise testing, resting transthoracic echocardiogram and health-related quality of life assessment were obtained before and at 6 months after CRT implantation in 37 patients with moderate-to-severe CHF. Patients were randomized after CRT to either a 24-week HIIT group (90-95% peak heart rate, 2 days per week) or to a usual care group (CON). Mixed design 2 × 2 repeated measures ANOVA were used to test for differences within and in-between groups. RESULTS: Improvements in health-related quality of life (HIIT = 98.54%, CON = 123.47%), NYHA class (HIIT = 43.44%, CON = 38.30%) HR recovery at minute 1 (HIIT = 32.32%, CON = 42.94%), pulse pressure at peak effort (HIIT = 14.06%, CON = 9.52%, LVEF (HIIT = 42.17%, CON = 51.10%) and LV Mass (HIIT = 13.26%, CON = 11.88%) were similar in both groups (p > 0.05). Significant increases in CPET duration in the HIIT group (25.94%), and increases in peak VO2 (HIIT = 8.64%, CON = 4.85%) and percent-predicted VO2 (HIIT = 10.57%, CON = 4.26%) in both groups, were observed in the intention-to-treat analysis. CONCLUSION: Six months of HIIT in patients in CRT did not further improved indices of functional capacity and health-related quality of life, and LV structure and function, compared to CRT alone. However, HIIT led to further improvements in exercise performance. It remains unclear whether HIIT benefits patients in CRT to a similar degree as more conventional forms of exercise training previously shown to maximize benefits in CRT.info:eu-repo/semantics/publishedVersio

    Critérios Mandatórios para Programas de Reabilitação Cardíaca: Normas da Sociedade Portuguesa de Cardiologia 2018

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    Cardiac rehabilitation (CR) is a multidisciplinary process for patients recovering after an acute cardiac event or with chronic cardiovascular disease that reduces mortality and morbidity and improves quality of life. It is considered a cost-effective intervention and is expressly indicated in the guidelines of the major medical societies. In Portugal, only 8% of patients discharged from hospital after myocardial infarction are included in CR programs. In Europe overall, the percentage admitted to CR programs is 30%, while in the USA it is 20-30%. In view of the underuse of CR in Portugal, we call the attention of the health authorities to the need to increase the number and national coverage of CR programs, while maintaining high quality standards. The aim is for all patients resident in Portugal who are eligible for CR programs to have the same opportunities for access and attendance. In order to preserve the benefits and safety of this intervention, CR needs to be performed according to international guidelines. The fact that various initiatives in this field have been developed by different professional groups, some of them non-medical, that do not follow the European guidelines, has prompted us to prepare a series of norms defining mandatory criteria for CR, based on current knowledge and evidence. In this way we aim to ensure that the required increase in the number of CR programs, linked in a national network of CR centers, does not detract from the need to maintain their efficacy and quality. These criteria should serve as the basis for the future accreditation of CR centers in Portugal.info:eu-repo/semantics/publishedVersio

    Relationship of Left Ventricular Global Longitudinal Strain with Cardiac Autonomic Denervation As Assessed by 123I-mIBG Scintigraphy in Patients with Heart Failure with Reduced Ejection Fraction Submitted to Cardiac Resynchronization Therapy: Assessment of Cardiac Autonomic Denervation by GLS in Patients with Heart Failure with Reduced Ejection Fraction Submitted to CRT

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    BACKGROUND: Heart failure (HF) is associated with cardiac autonomic denervation (AD), which can be non-invasively assessed by 123I-metaiodobenzylguanidine (123I-mIBG) scintigraphy and has prognostic implications. We aimed to study the relationship between myocardial contractility assessed by global longitudinal strain (GLS) and AD assessed by 123I-mIBG scintigraphy in advanced HF. METHODS/RESULTS: BETTER-HF is a prospective randomized clinical trial including HF patients (pts) submitted to cardiac resynchronization therapy (CRT) who are submitted to a clinical, echocardiographic, and scintigraphic assessment before and 6 months after CRT. 81 pts were included. An echocardiographic response (absolute increase in left ventricular ejection fraction ≄ 10%) was observed in 73.7% of pts. A higher baseline late heart-to-mediastinum ratio (HMR) was associated with a better echocardiographic response. There was a significant association between late HMR and GLS at baseline and 6 months. At baseline, GLS had an AUC of 0.715 for discrimination for a late HMR < 1.6. A GLS cut-off of - 9% maximized the likelihood of correctly classifying a pt as having severe AD (HMR < 1.6). CONCLUSION: Myocardial contractility as assessed by GLS is moderately correlated with AD as assessed by 123I-mIBG scintigraphy and has a good discrimination for the identification of severe cardiac denervation. GLS may allow for a more readily accessible estimation of the degree of AD in advanced HF pts.info:eu-repo/semantics/publishedVersio

    Two-photon Lithography for 3D Magnetic Nanostructure Fabrication

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    Ferromagnetic materials have been utilised as recording media within data storage devices for many decades. Confinement of the material to a two dimensional plane is a significant bottleneck in achieving ultra-high recording densities and this has led to the proposition of three dimensional (3D) racetrack memories that utilise domain wall propagation along nanowires. However, the fabrication of 3D magnetic nanostructures of complex geometry is highly challenging and not easily achievable with standard lithography techniques. Here, by using a combination of two-photon lithography and electrochemical deposition, we show a new approach to construct 3D magnetic nanostructures of complex geometry. The magnetic properties are found to be intimately related to the 3D geometry of the structure and magnetic imaging experiments provide evidence of domain wall pinning at a 3D nanostructured junction

    Body composition and body fat distribution are related to cardiac autonomic control in non-alcoholic fatty liver disease patients

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    BACKGROUND/OBJECTIVES: Heart rate recovery (HRR), a cardiac autonomic control marker, was shown to be related to body composition (BC), yet this was not tested in non-alcoholic fatty liver disease (NAFLD) patients. The aim of this study was to determine if, and to what extent, markers of BC and body fat (BF) distribution are related to cardiac autonomic control in NAFLD patients. SUBJECTS/METHODS: BC was assessed with dual-energy X-ray absorptiometry in 28 NAFLD patients (19 men, 51±13 years, and 9 women, 47±13 years). BF depots ratios were calculated to assess BF distribution. Subjects’ HRR was recorded 1 (HRR1) and 2 min (HRR2) immediately after a maximum graded exercise test. RESULTS: BC and BF distribution were related to HRR; particularly weight, trunk BF and trunk BF-to-appendicular BF ratio showed a negative relation with HRR1 (r 1⁄4 0.613, r 1⁄4 0.597 and r 1⁄4 0.547, respectively, Po0.01) and HRR2 (r 1⁄4 0.484, r 1⁄4 0.446, Po0.05, and r 1⁄4 0.590, Po0.01, respectively). Age seems to be related to both HRR1 and HRR2 except when controlled for BF distribution. The preferred model in multiple regression should include trunk BF-to-appendicular BF ratio and BF to predict HRR1 (r2 1⁄4 0.549; Po0.05), and trunk BF-to-appendicular BF ratio alone to predict HRR2 (r2 1⁄4 0.430; Po0.001). CONCLUSIONS: BC and BF distribution were related to HRR in NAFLD patients. Trunk BF-to-appendicular BF ratio was the best independent predictor of HRR and therefore may be best related to cardiovascular increased risk, and possibly act as a mediator in age-related cardiac autonomic control variation.info:eu-repo/semantics/publishedVersio
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