2,550 research outputs found
Achievements in hypertension: A 25 year overview
AbstractOnly 25 years ago, the field of hypertension was challenged by retrospective clinical data and epidemiologic information suggesting that an elevated arterial pressure is a major risk factor for enhanced cardiovascular morbidity and mortality. Not only was antihypertensive therapy looked on by many as dangerous and fraught with severe and undesirable side effects, but its validity in reversing the course of disease was not yet demonstrated. This review discusses the dramatic new information amassed over the past 25 years that points to the new physiologic and clinical concepts concerning hypertension. It considers impressive new diagnostic techniques and methods designed to identify secondary forms of hypertension and target organ involvement. In summary, it outlines the feasibility of reversing overall (and cardiovascular) morbidity and mortality with an array of antihypertensive agents that provide the therapeutic ability to suppress most pathophysiologic pressor mechanisms of hypertensive disease. The lesson is clear: hypertension provides the greatest available challenge to the new era of preventive cardiology in the 21st century
Quantum spacetime and the renormalization group: Progress and visions
The quest for a consistent theory which describes the quantum microstructure
of spacetime seems to require some departure from the paradigms that have been
followed in the construction of quantum theories for the other fundamental
interactions. In this contribution we briefly review two approaches to quantum
gravity, namely, asymptotically safe quantum gravity and tensor models, based
on different theoretical assumptions. Nevertheless, the main goal is to find a
universal continuum limit for such theories and we explain how coarse-graining
techniques should be adapted to each case. Finally, we argue that although
seemingly different, such approaches might be just two sides of the same coin.Comment: 14 pages, 4 figures, Proceedings of "Progress and Visions in Quantum
Theory in View of Gravity: Bridging foundations of physics and mathematics",
Leipzig, 201
Family memories in the home: contrasting physical and digital mementos
We carried out fieldwork to characterise and compare physical and digital mementos in the home. Physical mementos are highly valued, heterogeneous and support different types of recollection. Contrary to expectations, we found physical mementos are not purely representational, and can involve appropriating common objects and more idiosyncratic forms. In contrast, digital mementos were initially perceived as less valuable, although participants later reconsidered this. Digital mementos were somewhat limited in function and expression, largely involving representational photos and videos, and infrequently accessed. We explain these digital limitations and conclude with design guidelines for digital mementos, including better techniques for accessing and integrating these into everyday life, allowing them to acquire the symbolic associations and lasting value that characterise their physical counterparts
Variations in Solar Luminosity from Time Scales of Minutes to Months
We present the power spectrum of solar irradiance during 1985 and 1987
obtained from the ACRIM project from time scales of minutes to months. At low
frequency the spectra are Lorentzian. At higher frequencies they are
proportional to . A linear, stochastic model of the turbulent heat
transfer between the granulation layer (modeled as a homogeneous thin layer
with a radiative boundary condition) and the rest of the convection zone
(modeled as a homogeneous thick layer with thermal and diffusion constants
appropriate the lower convection zone) predicts the observed spectrum.Comment: latex file, 1 figur
Reconstructing Cetacean Brain Evolution Using Computed Tomography
Until recently, there have been relatively few studies of brain mass and morphology in fossil cetaceans (dolphins, whales, and porpoises) because of difficulty accessing the matrix that fills the endocranial cavity of fossil cetacean skulls. As a result, our knowledge about cetacean brain evolution has been quite limited. By applying the noninvasive technique of computed tomography (CT) to visualize, measure, and reconstruct the endocranial morphology of fossil cetacean skulls, we can gain vastly more information at an unprecedented rate about cetacean brain evolution. Here, we discuss our method and demonstrate it with several examples from our fossil cetacean database. This approach will provide new insights into the little-known evolutionary history of cetacean brain evolution
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