8,989 research outputs found
Communications platform payload definition study, executive summary
Large geostationary communications platforms have been investigated in a number of studies since 1974 as a possible means to more effectively utilize the geostationary orbital arc and electromagnetic spectrum and to reduce overall satellite communications system costs. This NASA Lewis sponsored study addresses the commercial feasibility of various communications platform payload concepts circa 1998. It defines promising payload concepts, estimates recurring costs and identifies critical technologies needed to permit eventual commercialization. Ten communications service aggregation scenarios describing potential groupings of services were developed for a range of conditions. Payload concepts were defined for four of these scenarios: (1) Land Mobile Satellite Service (LMSS), meet 100% of CONUS plus Canada demand with a single platform; (2) Fixed Satellite Service (FSS) (Trunking + Customer Premises Service (CPS), meet 20% of CONUS demands; (3) FSS (Trunking + video distribution), 10 to 13% of CONUS demand; and (4) FSS (20% of demand) + Inter Satellite Links (ISL) + TDRSS/TDAS Data Distribution
Fas (CD95) induces rapid, TLR4/IRAK4-dependent release of pro-inflammatory HMGB1 from macrophages
Although Fas (CD95) is recognized as a death receptor that induces apoptosis, recent studies indicate that the Fas/FasL system can induce pro-inflammatory cytokine production by macrophages independent of conventional caspase-mediated apoptotic signaling. The precise mechanism(s) by which Fas activates macrophage inflammation is unknown. We hypothesized that Fas stimulates rapid release of high mobility group box 1 (HMGB1) that acts in an autocrine and/or paracrine manner to stimulate pro-inflammatory cytokine production via a Toll-like receptor-4 (TLR4)/Interleukin-1 receptor associated kinase-4 (IRAK4)-dependent mechanism. Following Fas activation, HMGB1 was released within 1 hr from viable RAW267.4 cells and primary murine peritoneal macrophages. HMGB1 release was more rapid following Fas activation compared to LPS stimulation. Neutralization of HMGB1 with an inhibitory anti-HMGB1 monoclonal antibody strongly inhibited Fas-induced production of tumor necrosis factor (TNF) and macrophage inflammatory protein-2 (MIP-2). Both Fas-induced HMGB1 release and associated pro-inflammatory cytokine production were significantly decreased from Tlr4-/- and Irak4-/- macrophages, but not Tlr2-/- macrophages. These findings reveal a novel mechanism underlying Fas-mediated pro-inflammatory physiological responses in macrophages. We conclude that Fas activation induces rapid, TLR4/IRAK4-dependent release of HMGB1 that contributes to Fas-mediated pro-inflammatory cytokine production by viable macrophages
Modeling, Reduction, and Control of a Helically Actuated Inertial Soft Robotic Arm via the Koopman Operator
Soft robots promise improved safety and capability over rigid robots when
deployed in complex, delicate, and dynamic environments. However, the infinite
degrees of freedom and highly nonlinear dynamics of these systems severely
complicate their modeling and control. As a step toward addressing this open
challenge, we apply the data-driven, Hankel Dynamic Mode Decomposition (HDMD)
with time delay observables to the model identification of a highly inertial,
helical soft robotic arm with a high number of underactuated degrees of
freedom. The resulting model is linear and hence amenable to control via a
Linear Quadratic Regulator (LQR). Using our test bed device, a dynamic,
lightweight pneumatic fabric arm with an inertial mass at the tip, we show that
the combination of HDMD and LQR allows us to command our robot to achieve
arbitrary poses using only open loop control. We further show that Koopman
spectral analysis gives us a dimensionally reduced basis of modes which
decreases computational complexity without sacrificing predictive power.Comment: Submitted to IEEE International Conference on Robotics and
Automation, 202
On the criticality of inferred models
Advanced inference techniques allow one to reconstruct the pattern of
interaction from high dimensional data sets. We focus here on the statistical
properties of inferred models and argue that inference procedures are likely to
yield models which are close to a phase transition. On one side, we show that
the reparameterization invariant metrics in the space of probability
distributions of these models (the Fisher Information) is directly related to
the model's susceptibility. As a result, distinguishable models tend to
accumulate close to critical points, where the susceptibility diverges in
infinite systems. On the other, this region is the one where the estimate of
inferred parameters is most stable. In order to illustrate these points, we
discuss inference of interacting point processes with application to financial
data and show that sensible choices of observation time-scales naturally yield
models which are close to criticality.Comment: 6 pages, 2 figures, version to appear in JSTA
Monitoring the impacts of trade agreements on food environments
The liberalization of international trade and foreign direct investment through
multilateral, regional and bilateral agreements has had profound implications
for the structure and nature of food systems, and therefore, for the availability,
nutritional quality, accessibility, price and promotion of foods in different
locations. Public health attention has only relatively recently turned to the links
between trade and investment agreements, diets and health, and there is currently
no systematic monitoring of this area. This paper reviews the available evidence on the links between trade agreements, food environments and diets from an obesity and non-communicable disease (NCD) perspective. Based on the key issues identified through the review, the paper outlines an approach for monitoring the potential impact of trade agreements on food environments and
obesity/NCD risks. The proposed monitoring approach encompasses a set of guiding principles, recommended procedures for data collection and analysis, and quantifiable âminimalâ, âexpandedâ and âoptimalâ measurement indicators to be tailored to national priorities, capacity and resources. Formal risk assessment processes of existing and evolving trade and investment agreements,
which focus on their impacts on food environments will help inform the development of healthy trade policy, strengthen domestic nutrition and health
policy space and ultimately protect population nutrition.The following organizations provided funding support for the travel of participants
to Italy for this meeting and the preparation of background research papers: The Rockefeller Foundation, International Obesity Taskforce (IOTF), University of
Auckland, Deakin University, The George Institute, University of Sydney, Queensland University of Technology, University
of Oxford, University of Pennsylvania Perelman School of Medicine, World Cancer Research Fund International, University of Toronto, and The Australian National
University. The Faculty of Health at Deakin University kindly supported the costs for open access availability of this paper,
and the Australian National Health and Medical Research Council Centre for Research Excellence in Obesity Policy and Food Systems (APP1041020) supported the coordination and finalizing of INFORMAS manuscripts
A proposed approach to monitor private-sector policies and practices related to food environments, obesity and non-communicable disease prevention
Private-sector organizations play a critical role in shaping the food environments
of individuals and populations. However, there is currently
very limited independent monitoring of private-sector actions related to
food environments. This paper reviews previous efforts to monitor the
private sector in this area, and outlines a proposed approach to monitor
private-sector policies and practices related to food environments, and
their influence on obesity and non-communicable disease (NCD) prevention.
A step-wise approach to data collection is recommended, in which
the first (âminimalâ) step is the collation of publicly available food and
nutrition-related policies of selected private-sector organizations. The
second (âexpandedâ) step assesses the nutritional composition of each
organizationâs products, their promotions to children, their labelling
practices, and the accessibility, availability and affordability of their
products. The third (âoptimalâ) step includes data on other commercial
activities that may influence food environments, such as political lobbying
and corporate philanthropy. The proposed approach will be further
developed and piloted in countries of varying size and income levels.
There is potential for this approach to enable national and international
benchmarking of private-sector policies and practices, and to inform
efforts to hold the private sector to account for their role in obesity and
NCD prevention
Principles behind evaluations of national food and beverage taxes and other regulatory efforts
Non-PRIFPRI3; ISIPHN
Report of the Working Group on `W Mass and QCD' (Phenomenology Workshop on LEP2 Physics, Oxford, April 1997)
The W Mass and QCD Working Group discussed a wide variety of topics relating
to present and future measurements of M(W) at LEP2, including QCD backgrounds
to W+W- production. Particular attention was focused on experimental issues
concerning the direct reconstruction and threshold mass measurements, and on
theoretical and experimental issues concerning the four jet final state. This
report summarises the main conclusions.Comment: 43 pages LaTeX and 15 encapsulated postscript figures. Uses epsfig
and ioplppt macros. Full Proceedings to be published in Journal of Physics
Academic self-concept, gender and single-sex schooling
This paper assesses gender differences in academic self-concept for a cohort of children born in 1958 (the National Child Development Study). We address the question of whether attending single-sex or co-educational schools affected studentsâ perceptions of their own academic abilities (academic self-concept). Academic selfconcept was found to be highly gendered, even controlling for prior test scores. Boys had higher self-concepts in maths and science, and girls in English. Single-sex schooling reduced the gender gap in self-concept, while selective schooling was linked to lower academic self-concept overall
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