1,603 research outputs found
Do Childhood Cancer Survivors Meet the Diet and Physical Activity Guidelines? A Review of Guidelines and Literature
Despite advances in cancer treatment, childhood cancer survivors are at higher risk of developing chronic health conditions than peers who do not have cancer. Being overweight or obese adds to the already elevated risk of cardiovascular diseases and metabolic abnormalities that childhood cancer survivors experience. Diet and physical activity are modifiable behaviors that reduce obesity risk and have been shown to improve cancer survival in adult cancer survivors. Specific guidelines have been developed for cancer survivors that provide advice on nutrition, physical activity and weight management following cancer diagnosis and treatment. In this review, we report on existing nutrition and physical activity guidelines for cancer survivors, supplemented by available literature on diet and physical activity status of childhood cancer survivors and their associations with health-related outcomes. The 2012 American Cancer Society (ACS) and the 2008 Children's Oncology Group (COG) guidelines provide similar advice on diet but the ACS guidelines also offer specific advice on physical activity and weight management. Thirty-one observational studies and 18 intervention trials published prior to June 2012 that met the inclusion criteria were reviewed. Results suggest that a high proportion of childhood cancer survivors had poor adherence to dietary and physical activity guidelines. Although findings from existing intervention trials are preliminary due to small sample size, available evidence suggests that exercise intervention is safe and feasible for patients and survivors of childhood cancer. Childhood cancer survivors should be encouraged to engage in physical activity, adopt a healthful diet, and maintain a healthy weight throughout cancer survivorship. (word count: 250
Air/Sea Transfer of Highly Soluble Gases Over Coastal Waters
The deposition of soluble trace gases to the sea surface is not well studied due to a lack of flux measurements over the ocean. Here we report simultaneous air/sea eddy covariance flux measurements of water vapor, sulfur dioxide (SO2), and momentum from a coastal North Atlantic pier. Gas transfer velocities were on average about 20% lower for SO2 than for H2O. This difference is attributed to the difference in molecular diffusivity between the two molecules (DSO2/DH2O = 0.5), in reasonable agreement with bulk parameterizations in air/sea gas models. This study demonstrates that it is possible to observe the effect of molecular diffusivity on air-side resistance to gas transfer. The slope of observed relationship between gas transfer velocity and friction velocity is slightly smaller than predicted by gas transfer models, possibly due to wind/wave interactions that are unaccounted for in current models
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An implicit method for hyperbolic conservation laws on meshes with small cells in one dimension
In this paper we study a new method for solving hyperbolic conservation laws on a Cartesian mesh with some small cells. Our main task here is to devise a stable algorithm in the small zones. An algorithm proposed by Berger and LeVeque combines the small zones with neighboring zones and solves rotated Riemann problems. This method is very geometrically oriented. It requires knowledge of the areas of the small cells, as well as the areas of cells contained in various {open_quote}boxes{close_quotes} drawn from the edges of the small cells. Here we propose a more algebraic algorithm: we combine an implicit method with an explicit second-order conservative finite difference scheme. In section 2 the basic algorithm in one dimension is presented, as well as the slopes calculations and the iterative procedure. In section 3 we present some numerical results for the 1-D advection equation and the inviscid Burger`s equation
Flight-Determined Subsonic Lift and Drag Characteristics of Seven Lifting-Body and Wing-Body Reentry Vehicle Configurations With Truncated Bases
This paper examines flight-measured subsonic lift and drag characteristics of seven lifting-body and wing-body reentry vehicle configurations with truncated bases. The seven vehicles are the full-scale M2-F1, M2-F2, HL-10, X-24A, X-24B, and X-15 vehicles and the Space Shuttle prototype. Lift and drag data of the various vehicles are assembled under aerodynamic performance parameters and presented in several analytical and graphical formats. These formats unify the data and allow a greater understanding than studying the vehicles individually allows. Lift-curve slope data are studied with respect to aspect ratio and related to generic wind-tunnel model data and to theory for low-aspect-ratio planforms. The proper definition of reference area was critical for understanding and comparing the lift data. The drag components studied include minimum drag coefficient, lift-related drag, maximum lift-to-drag ratio, and, where available, base pressure coefficients. The effects of fineness ratio on forebody drag were also considered. The influence of forebody drag on afterbody (base) drag at low lift is shown to be related to Hoerner's compilation for body, airfoil, nacelle, and canopy drag. These analyses are intended to provide a useful analytical framework with which to compare and evaluate new vehicle configurations of the same generic family
Air/sea DMS gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed
Shipboard measurements of eddy covariance dimethylsulfide (DMS) air–sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. Gas transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s−1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air–sea gas flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near-surface water-side turbulence, and decrease interfacial gas transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air–sea exchange of DMS is controlled by interfacial rather than bubble-mediated gas transfer under high wind speed conditions
Lorenz-like systems and classical dynamical equations with memory forcing: a new point of view for singling out the origin of chaos
A novel view for the emergence of chaos in Lorenz-like systems is presented.
For such purpose, the Lorenz problem is reformulated in a classical mechanical
form and it turns out to be equivalent to the problem of a damped and forced
one dimensional motion of a particle in a two-well potential, with a forcing
term depending on the ``memory'' of the particle past motion. The dynamics of
the original Lorenz system in the new particle phase space can then be
rewritten in terms of an one-dimensional first-exit-time problem. The emergence
of chaos turns out to be due to the discontinuous solutions of the
transcendental equation ruling the time for the particle to cross the
intermediate potential wall. The whole problem is tackled analytically deriving
a piecewise linearized Lorenz-like system which preserves all the essential
properties of the original model.Comment: 48 pages, 25 figure
Yours ever (well, maybe): Studies and signposts in letter writing
Electronic mail and other digital communications technologies seemingly threaten to end the era of handwritten and typed letters, now affectionately seen as part of snail mail. In this essay, I analyze a group of popular and scholarly studies about letter writing-including examples of pundits critiquing the use of e-mail, etiquette manuals advising why the handwritten letter still possesses value, historians and literary scholars studying the role of letters in the past and what it tells us about our present attitudes about digital communications technologies, and futurists predicting how we will function as personal archivists maintaining every document including e-mail. These are useful guideposts for archivists, providing both a sense of the present and the past in the role, value and nature of letters and their successors. They also provide insights into how such documents should be studied, expanding our gaze beyond the particular letters, to the tools used to create them and the traditions dictating their form and function. We also can discern a role for archivists, both for contributing to the literature about documents and in using these studies and commentaries, suggesting not a new disciplinary realm but opportunities for new interdisciplinary work. Examining a documentary form makes us more sensitive to both the innovations and traditions as it shifts from the analog to the digital; we can learn not to be caught up in hysteria or nostalgia about one form over another and archivists can learn about what they might expect in their labors to document society and its institutions. At one time, paper was part of an innovative technology, with roles very similar to the Internet and e-mail today. It may be that the shifts are far less revolutionary than is often assumed. Reading such works also suggests, finally, that archivists ought to rethink how they view their own knowledge and how it is constructed and used. © 2010 Springer Science+Business Media B.V
Icebergs in the North Atlantic: Modelling circulation changes and glacio-marine deposition
In order to investigate meltwater events in the North Atlantic, a simple iceberg generation, drift, and melting routine was implemented in a high-resolution OGCM. Starting from the modelled last glacial state, every 25th day cylindrical model icebergs 300 meters high were released at 32 specific points along the coasts. Icebergs launched at the Barents Shelf margin spread a light meltwater lid over the Norwegian and Greenland Seas, shutting down the deep convection and the anti-clockwise circulation in this area. Due to the constraining ocean circulation, the icebergs produce a tongue of relatively cold and fresh water extending eastward from Hudson Strait that must develop at this location, regardless of iceberg origin. From the total amount of freshwater inferred by the icebergs, the thickness of the deposited IRD could be calculated in dependance of iceberg sediment concentration. In this way, typical extent and thickness of Heinrich layers could be reproduced, running the model for 250 years of steady state with constant iceberg meltwater inflow
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Near-Real-Time Measurement Of Sea-Salt Aerosol During the Seas Campaign: Comparison Of Emission-Based Sodium Detection With an Aerosol Volatility Technique
The first deployment of an emission-based aerosol sodium detector (ASD), designed to chemically characterize marine aerosols on a near-real-time basis, is reported. Deployment occurred as part of the Shoreline Environment Aerosol Study ( SEAS) from 16 April to 1 May 2000 at Bellows Air Force Base on the east side of Oahu, where the University of Hawaii\u27s Department of Oceanography maintains a tower for aerosol measurements. The instrument was operated in size-unsegregated mode and measurements were made that included two extended continuous sampling periods, each of which lasted for 24 h. During this time, the ASD was compared with measurements that used aerosol volatility coupled with optical particle counting to infer sea-salt size distributions. A reasonable agreement was obtained between the instruments when sampling in clean air, suggesting that under these conditions both approaches can provide reliable sea-salt distributions. The combination of these measurements suggested that sea salt was the dominant constituent of aerosol particles with diameters larger than 500 nm and that sulfate was the dominant constituent at smaller diameters during clean air sampling
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