Fatty acid composition of plasma lipids in healthy Portuguese children: Is the Mediterranean diet disappearing?

Background: Adults and children in Mediterranean countries are believed to consume a Mediterranean-type diet wh ich is h ig her in monounsaturated a nd n-3 polyunsaturated fatty acids than compared to central and northern parts of Europe and has preventive effects for cardiovascular risks. Subjects and Methods: in preschool children from Porto, Portugal (n = 35) and Munich, Germany (n = 18) we determined the plasma phospholipid fatty acid composition considered as a biomarker for dietary fat intake. Results: The plasma phospholipid contents of total saturated fatty acids are similar in both groups, but the Portuguese children have lower values of monounsaturated and n-3 polyunsaturated fatty acids. The results indicate that the food habits of Portuguese children are even less close to the traditional Mediterranean diet than those of German children, Conclusions: Efforts should be made to encourage young families as well as manufacturers and distributors of food products in Portugal to emphasize traditional Mediterranean food habits, especially in young children. Copyright (C) 2001 S. Karger AG. Basel

Characterizing the Hadley circulation response through regional climate feedbacks

The robust weakening of the tropical atmospheric circulation in projections of anthropogenic warming is associated with substantial changes in regional and global climate. The present study focuses on understanding the response of the annual-mean Hadley circulation from a perspective of interactions between climate feedbacks and tropical circulation. Simulations from an ensemble of coupled ocean–atmosphere models are used to quantify changes in Hadley cell strength in terms of feedbacks, radiative forcing, ocean heat uptake, atmospheric eddies, and gross moist stability. Climate feedbacks are calculated for the model integrations from phase 5 of CMIP (CMIP5) using radiative kernels. Tropical mean circulation is found to be reduced by up to 2.6% K^(−1) for an abrupt quadrupling of carbon dioxide concentration. The weakening is characterized by an increase in gross moist stability, by an increase in eddy heat flux, and by positive extratropical feedbacks, such as those associated with lapse rate and sea ice response. Understanding the impact of radiative feedbacks on the large-scale circulation provides a framework for constraining uncertainty in the dynamic climate response, including the hydrological cycle

Fatty acid composition of plasma lipids in healthy Portuguese children: Is the Mediterranean diet disappearing?

Background: Adults and children in Mediterranean countries are believed to consume a Mediterranean-type diet wh ich is h ig her in monounsaturated a nd n-3 polyunsaturated fatty acids than compared to central and northern parts of Europe and has preventive effects for cardiovascular risks. Subjects and Methods: in preschool children from Porto, Portugal (n = 35) and Munich, Germany (n = 18) we determined the plasma phospholipid fatty acid composition considered as a biomarker for dietary fat intake. Results: The plasma phospholipid contents of total saturated fatty acids are similar in both groups, but the Portuguese children have lower values of monounsaturated and n-3 polyunsaturated fatty acids. The results indicate that the food habits of Portuguese children are even less close to the traditional Mediterranean diet than those of German children, Conclusions: Efforts should be made to encourage young families as well as manufacturers and distributors of food products in Portugal to emphasize traditional Mediterranean food habits, especially in young children. Copyright (C) 2001 S. Karger AG. Basel

Coupled High-Latitude Climate Feedbacks and Their Impact on Atmospheric Heat Transport

The response of atmospheric heat transport to anthropogenic warming is determined by the anomalous meridional energy gradient. Feedback analysis offers a characterization of that gradient and hence reveals how uncertainty in physical processes may translate into uncertainty in the circulation response. However, individual feedbacks do not act in isolation. Anomalies associated with one feedback may be compensated by another, as is the case for the positive water vapor and negative lapse rate feedbacks in the tropics. Here a set of idealized experiments are performed in an aquaplanet model to evaluate the coupling between the surface albedo feedback and other feedbacks, including the impact on atmospheric heat transport. In the tropics, the dynamical response manifests as changes in the intensity and structure of the overturning Hadley circulation. Only half of the range of Hadley cell weakening exhibited in these experiments is found to be attributable to imposed, systematic variations in the surface albedo feedback. Changes in extratropical clouds that accompany the albedo changes explain the remaining spread. The feedback-driven circulation changes are compensated by eddy energy flux changes, which reduce the overall spread among experiments. These findings have implications for the efficiency with which the climate system, including tropical circulation and the hydrological cycle, adjusts to high-latitude feedbacks over climate states that range from perennial or seasonal ice to ice-free conditions in the Arctic

The influence of regional feedbacks on circulation sensitivity

Weakening of the tropical overturning circulation in a warmer world is a robust feature in climate models. Here an idealized representation of ocean heat flux drives a Walker cell in an aquaplanet simulation. A goal of the study is to assess the influence of the Walker circulation on the magnitude and structure of climate feedbacks, as well as to global sensitivity. We compare two CO_2 perturbation experiments, one with and one without a Walker circulation, to isolate the differences attributable to tropical circulation and associated zonal asymmetries. For an imposed Walker circulation, the subtropical shortwave cloud feedback is reduced, which manifests as a weaker tropical-subtropical anomalous energy gradient and consequently a weaker slow down of the Hadley circulation, relative to the case without a Walker circulation. By focusing on the coupled feedback circulation system, these results offer insights into understanding changes in atmospheric circulation and hence the hydrological cycle under global warming

Coupled High-Latitude Climate Feedbacks and Their Impact on Atmospheric Heat Transport

The response of atmospheric heat transport to anthropogenic warming is determined by the anomalous meridional energy gradient. Feedback analysis offers a characterization of that gradient and hence reveals how uncertainty in physical processes may translate into uncertainty in the circulation response. However, individual feedbacks do not act in isolation. Anomalies associated with one feedback may be compensated by another, as is the case for the positive water vapor and negative lapse rate feedbacks in the tropics. Here a set of idealized experiments are performed in an aquaplanet model to evaluate the coupling between the surface albedo feedback and other feedbacks, including the impact on atmospheric heat transport. In the tropics, the dynamical response manifests as changes in the intensity and structure of the overturning Hadley circulation. Only half of the range of Hadley cell weakening exhibited in these experiments is found to be attributable to imposed, systematic variations in the surface albedo feedback. Changes in extratropical clouds that accompany the albedo changes explain the remaining spread. The feedback-driven circulation changes are compensated by eddy energy flux changes, which reduce the overall spread among experiments. These findings have implications for the efficiency with which the climate system, including tropical circulation and the hydrological cycle, adjusts to high-latitude feedbacks over climate states that range from perennial or seasonal ice to ice-free conditions in the Arctic

High power beam profile monitor with optical transition radiation

A simple monitor has been built to measure the profile of the high power beam (800 kW) delivered by the CEBAF accelerator at Jefferson Lab. The monitor uses the optical part of the forward transition radiation emitted from a thin carbon foil. The small beam size to be measured, about 100 {mu}m, is challenging not only for the power density involved but also for the resolution the instrument must achieve. An important part of the beam instrumentation community believes the radiation being emitted into a cone of characteristic angle 1/{gamma} is originated from a region of transverse dimension roughly {lambda}{gamma}; thus the apparent size of the source of transition radiation would become very large for highly relativistic particles. This monitor measures 100 {mu}m beam sizes that are much smaller than the 3.2 mm {lambda}{gamma} limit; it confirms the statement of Rule and Fiorito that optical transition radiation can be used to image small beams at high energy. The present paper describes the instrument and its performance. The authors tested the foil in, up to 180 {mu}A of CW beam without causing noticeable beam loss, even at 800 MeV, the lowest CEBAF energy