492 research outputs found
Land of Addicts? An Empirical Investigation of Habit-Based Asset Pricing Models
A popular explanation of aggregate stock market behavior suggests that assets are priced as if there were a representative investor whose utility is a power function of the difference between aggregate consumption and a “habit” level, where the habit is some function of lagged and (possibly) contemporaneous consumption. But theory does not provide precise guidelines about the parametric functional relationship between the habit and aggregate consumption. This makes for- mal estimation and testing challenging; at the same time, it raises an empirical question about the functional form of the habit that best explains asset pricing data. This paper studies the ability of a general class of habit-based asset pricing models to match the conditional moment restrictions implied by asset pricing theory. Our approach is to treat the functional form of the habit as unknown, and to estimate it along with the rest of the model’s finite dimensional parameters. This semiparametric approach allows us to empirically evaluate a number of interesting hypotheses about the specification of habit-based asset pricing models. Using stationary quarterly data on consumption growth, assets returns and instruments, our empirical results indicate that the estimated habit function is nonlinear, the habit formation is internal, and the estimated time-preference parameter and the power utility parameter are sensible. In addition, our estimated habit function generates a positive stochastic discount factor (SDF) proxy and performs well in explaining cross-sectional stock return data. We find that an internal habit SDF proxy can explain a cross-section of size and book-market sorted portfolio equity returns better than (i) the Fama and French (1993) three-factor model, (ii) the Lettau and Ludvigson (2001b) scaled consumption CAPM model, (iii) an external habit SDF proxy, (iv) the classic CAPM, and (v) the classic consumption CAPM
A review, timeline, and categorization of learning design tools
Enabling teachers to define or portray efficient teaching ideas for
sharing, reuse or adaptation has attracted the interest of Learning Design
researchers and has led to the development of a variety of learning design tools.
In this paper, we introduce a multi-dimensional framework for the analysis of
learning design tools and use it to review twenty-nine tools currently available to
researchers and practitioners. Lastly, we categorise these tools according to the
main functionality that they offer
Cell walls of the dimorphic fungal pathogens Sporothrix schenckii and Sporothrix brasiliensis exhibit bilaminate structures and sloughing of extensive and intact layers
This work was supported by the Fundação Carlos Chagas de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), grants E-26/202.974/2015 and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), grants 229755/2013-5, Brazil. LMLB is a senior research fellow of CNPq and Faperj. NG acknowledged support from the Wellcome Trust (Trust (097377, 101873, 200208) and MRC Centre for Medical Mycology (MR/N006364/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
International Veterinary Epilepsy Task Force recommendations for systematic sampling and processing of brains from epileptic dogs and cats
Traditionally, histological investigations of the epileptic brain are required to identify epileptogenic brain lesions, to evaluate the impact of seizure activity, to search for mechanisms of drug-resistance and to look for comorbidities. For many instances, however, neuropathological studies fail to add substantial data on patients with complete clinical work-up. This may be due to sparse training in epilepsy pathology and or due to lack of neuropathological guidelines for companion animals.
The protocols introduced herein shall facilitate systematic sampling and processing of epileptic brains and therefore increase the efficacy, reliability and reproducibility of morphological studies in animals suffering from seizures.
Brain dissection protocols of two neuropathological centres with research focus in epilepsy have been optimised with regards to their diagnostic yield and accuracy, their practicability and their feasibility concerning clinical research requirements.
The recommended guidelines allow for easy, standardised and ubiquitous collection of brain regions, relevant for seizure generation. Tissues harvested the prescribed way will increase the diagnostic efficacy and provide reliable material for scientific investigations
Neuroprotection or Increased Brain Damage Mediated by Temperature in Stroke Is Time Dependent
The control of temperature during the acute phase of stroke may be a new therapeutic target that can be applied in all stroke patients, however therapeutic window or timecourse of the temperature effect is not well established. Our aim is to study the association between changes in body temperature in the first 72 hours and outcome in patients with ischemic (IS) and hemorrhagic (ICH) stroke. We prospectively studied 2931 consecutive patients (2468 with IS and 463 with ICH). Temperature was obtained at admission, and at 24, 48 and 72 hours after admission. Temperature was categorized as low (<36°C), normal (36–37°C) and high (>37°C). As the main variable, we studied functional outcome at 3 months determined by modified Rankin Scale
A Doctor Facing Turbulent Times: Antoni Tomasz Jurasz, Citizen of the World
The eponymous of the Jurasz procedure is Antoni Tomasz Jurasz (1882–1961). The procedure is a standard approach to treating mature pancreatic pseudocysts that are in contact with the stomach, although recent advances in instrumentation have empowered surgeons to perform pseudocystogastrostomy laparoscopically for this problem. Dr. Jurasz was born in Germany but felt himself as Polish as his ancestors. He graduated from Heidelberg with a degree in medicine. Over the following years, he developed a German surgery school, especially helping with the achievements of Erich Lexer and Erwin Payr. During the period between World Wars I and II, Jurasz chaired and led the Surgery Clinic of Poznan University in Poland; and he gave lectures and performed public operations abroad. These activities, together with articles published in German-, French-, and English-language medical journals, made him a world-renowned figure in the field of abdominal and thyroid surgery. During World War II, he revealed exceptional traits, taking part in the September Campaign in Poland as a surgeon. He then organized the Polish School of Medicine and the Paderewski Hospital in Edinburgh. Despite his outstanding mind, generosity, and merits, A. T. Jurasz became persona non grata in Communist Poland, which ultimately persuaded him to emigrate to the United States
Prevalence and correlates of frailty in an older rural African population:findings from the HAALSI cohort study
Background: Frailty is a key predictor of death and dependency, yet little is known about frailty in sub-Saharan Africa despite rapid population ageing. We describe the prevalence and correlates of phenotypic frailty using data from the Health and Aging in Africa: Longitudinal Studies of an INDEPTH Community cohort. Methods: We analysed data from rural South Africans aged 40 and over. We used low grip strength, slow gait speed, low body mass index, and combinations of self-reported exhaustion, decline in health, low physical activity and high self-reported sedentariness to derive nine variants of a phenotypic frailty score. Each frailty category was compared with self-reported health, subjective wellbeing, impairment in activities of daily living and the presence of multimorbidity. Cox regression analyses were used to compare subsequent all-cause mortality for non-frail (score 0), pre-frail (score 1–2) and frail participants (score 3+). Results: Five thousand fifty nine individuals (mean age 61.7 years, 2714 female) were included in the analyses. The nine frailty score variants yielded a range of frailty prevalences (5.4% to 13.2%). For all variants, rates were higher in women than in men, and rose steeply with age. Frailty was associated with worse subjective wellbeing, and worse self-reported health. Both prefrailty and frailty were associated with a higher risk of death during a mean 17 month follow up for all score variants (hazard ratios 1.29 to 2.41 for pre-frail vs non-frail; hazard ratios 2.65 to 8.91 for frail vs non-frail). Conclusions: Phenotypic frailty could be measured in this older South African population, and was associated with worse health, wellbeing and earlier death
Gating a single-molecule transistor with individual atoms
Transistors, regardless of their size, rely on electrical gates to control the
conductance between source and drain contacts. In atomic-scale transistors,
this conductance is sensitive to single electrons hopping via individual
orbitals1, 2. Single-electron transport in molecular transistors has been
previously studied using top-down approaches to gating, such as lithography
and break junctions1, 3, 4, 5, 6, 7, 8, 9, 10, 11. But atomically precise
control of the gate—which is crucial to transistor action at the smallest size
scales—is not possible with these approaches. Here, we used individual charged
atoms, manipulated by a scanning tunnelling microscope12, to create the
electrical gates for a single-molecule transistor. This degree of control
allowed us to tune the molecule into the regime of sequential single-electron
tunnelling, albeit with a conductance gap more than one order of magnitude
larger than observed previously8, 11, 13, 14. This unexpected behaviour arises
from the existence of two different orientational conformations of the
molecule, depending on its charge state. Our results show that strong coupling
between these charge and conformational degrees of freedom leads to new
behaviour beyond the established picture of single-electron transport in
atomic-scale transistors
Isospora araponga sp. n. (Apicomplexa: Eimeriidae), a new species of Isospora Schneider from a bare-throated bellbird, Procnias nudicollis (Vieillot, 1817) (Passeriformes: Cotingidae) from Brazil
Rosmarinic Acid, Active Component of Dansam-Eum Attenuates Ototoxicity of Cochlear Hair Cells through Blockage of Caspase-1 Activity
Cisplatin causes auditory impairment due to the apoptosis of auditory hair cells. There is no strategy to regulate ototoxicity by cisplatin thus far. Dansam-Eum (DSE) has been used for treating the central nerve system injury including hearing loss in Korea. However, disease-related scientific investigation by DSE has not been elucidated. Here, we demonstrated that DSE and its component rosmarinic acid (RA) were shown to inhibit apoptosis of the primary organ of Corti explants as well as the auditory cells. Administration of DSE and RA reduced the thresholds of the auditory brainstem response in cisplatin-injected mice. A molecular docking simulation and a kinetic assay show that RA controls the activity of caspase-1 by interaction with the active site of caspase-1. Pretreatment of RA inhibited caspase-1 downstream signal pathway, such as the activation of caspase-3 and 9, release of cytochrome c, translocation of apoptosis-inducing factor, up-regulation of Bax, down-regulation of Bcl-2, generation of reactive oxygen species, and activation of nuclear factor-κB. Anticancer activity by cisplatin was not affected by treatment with RA in SNU668, A549, HCT116, and HeLa cells but not B16F10 cells. These findings show that blocking a critical step by RA in apoptosis may be useful strategy to prevent harmful side effects of ototoxicity in patients with having to undergo chemotherapy
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