Attitude measurement: Principles and sensors

Tools used in the measurement of satellite attitude are described. Attention is given to the elements that characterize an attitude sensor, the references employed (stars, moon, Sun, Earth, magnetic fields, etc.), and the detectors (optical, magnetic, and inertial). Several examples of attitude sensors are described, including sun sensors, star sensors, earth sensors, triaxial magnetometers, and gyrometers. Finally, sensor combinations that make it possible to determine a complete attitude are considered; the SPOT attitude measurement system and a combined CCD star sensor-gyrometer system are discussed

Dynamics of Race, Culture and Key Indicators of Health in the Nation's 100 Largest Cities and Their Suburbs

Profiles the 2000 status of, and changes since 1990, in rates of health and health-related measures to identify patterns in race/ethnicity, foreign-born status, language use, poverty, income, low birth weight, teen births, prenatal care, and tuberculosis

High resolution imaging with Fresnel interferometric arrays: suitability for exoplanet detection

We propose a new kind of interferometric array that yields images of high dynamic range and large field. The numerous individual apertures in this array form a pattern related to a Fresnel zone plate. This array can be used for astrophysical imaging over a broad spectral bandwidth spanning from the U.V. (50 nanometers) to the I.R. (20 microns). Due to the long focal lengths involved, this instrument requires formation-flying of two space borne vessels. We present the concept and study the S/N ratio in different situations, then apply these results to probe the suitability of this concept to detect exoplanets.Comment: 12 pages, 19 figures, to be published in A&

Local 4/5-Law and Energy Dissipation Anomaly in Turbulence

A strong local form of the ``4/3-law'' in turbulent flow has been proved recently by Duchon and Robert for a triple moment of velocity increments averaged over both a bounded spacetime region and separation vector directions, and for energy dissipation averaged over the same spacetime region. Under precisely stated hypotheses, the two are proved to be proportional, by a constant 4/3, and to appear as a nonnegative defect measure in the local energy balance of singular (distributional) solutions of the incompressible Euler equations. Here we prove that the energy defect measure can be represented also by a triple moment of purely longitudinal velocity increments and by a mixed moment with one longitudinal and two tranverse velocity increments. Thus, we prove that the traditional 4/5- and 4/15-laws of Kolmogorov hold in the same local sense as demonstrated for the 4/3-law by Duchon-Robert.Comment: 14 page

PATIENT PROTECTION AND AFFORDABLE CARE ACT OF 2010: Advancing Health Equity for Racially and Ethnically Diverse Populations

Racial/ethnic disparities in health and health care in the United States are persistent and well documented. Communities of color fare far worse than their white counterparts across a range of health indicators: life expectancy, infant mortality, prevalence of chronic diseases, self-rated health status, insurance coverage, and many others.1 As the nation’s population continues to become increasingly diverse—people of color are projected to comprise 54% of the U.S. population by 2050 and more than half of U.S. children by 20232— these disparities are likely to grow if left unaddressed. Recent health care reform legislation, while not a panacea for eliminating health disparities, off ers an important fi rst step and an unprecedented opportunity to improve health equity in the United States. Reforming the nation’s health care system was President Obama’s top domestic priority when he was sworn into offi ce in January 2009. Th e road to reform was complex and unoffi cially started in summer of 2009 when House and Senate committees began to draft legislation. On November 7, 2009, the House of Representatives passed its health care reform proposal, Th e Aff ordable Health Choices Act of 2009 (H.R. 3962). On December 24, 2009, the Senate passed its own proposal for health care reform, Th e Patient Protection and Aff ordable Care Act (H.R. 3590)*, which was a merged version of the Senate Finance Committee’s America’s Health Future Act (S.1796) and the Senate Committee on Health, Education, Labor, and Pensions’ Aff ordable Health Choices Act (S. 1697).† Eff orts to reconcile diff erences between the Senate and House bills were stymied by the death of Senator Edward Kennedy (D-MA), a lifelong proponent of health care reform and critical force in securing a proposal’s passage in the Senate. Faced with limited options and expecting that a compromise bill could not get Senate support, the House passed the Senate’s proposal and Th e Patient Protection and Aff ordable Care Act (ACA) was signed into law by President Obama on March 23, 2010 (Pub. L. No. 111-148).‡ On March 30, 2010, the ACA was amended by Th e Health Care and Education Reconciliation Act of 2010 (H.R. 4872). According to Congressional Budget Offi ce (CBO) estimates, the ACA, as reconciled by H.R. 4872, will reduce the defi cit by $143 billion over the next decade and decrease the number of non-elderly uninsured by 32 million, leaving 23 million uninsured— approximately one-third of whom would be undocumented immigrants.3 Th is report provides a comprehensive review of general and specifi c ACA provisions with the potential to signifi cantly improve health and health care for millions of diverse populations and their communities. Th e narrative that follows identifi es these provisions, discusses why they are important, and considers challenges that may lie ahead in implementing them. We have organized this presentation in three major sections. Th e next section discusses provisions that explicitly address health disparities, such as those concerning data collection by race/ethnicity, workforce diversity, cultural competence, health disparities research, health disparities initiatives in prevention, and health equity in health insurance reform, and discusses their implications for racially and ethnically diverse communities. Section III describes general provisions, including health insurance reforms, access to care, quality improvement, cost containment, public health and social determinants of health, all of which are likely to have major implications for diverse communities. An accompanying appendix identifi es these provisions, provides a timetable and, where identifi ed in the legislation, the federal agencies responsible for implementation, as well as allocations as of June 30, 2010. Section IV discusses issues that will be critical in realizing the full potential of health care reform and highlights questions and directions for the future, particularly in context of important priorities for reducing racial/ethnic health disparities that were left unaddressed

Simple Systems with Anomalous Dissipation and Energy Cascade

We analyze a class of linear shell models subject to stochastic forcing in finitely many degrees of freedom. The unforced systems considered formally conserve energy. Despite being formally conservative, we show that these dynamical systems support dissipative solutions (suitably defined) and, as a result, may admit unique (statistical) steady states when the forcing term is nonzero. This claim is demonstrated via the complete characterization of the solutions of the system above for specific choices of the coupling coefficients. The mechanism of anomalous dissipations is shown to arise via a cascade of the energy towards the modes ($a_n$) with higher $n$; this is responsible for solutions with interesting energy spectra, namely \EE |a_n|^2 scales as $n^{-\alpha}$ as $n\to\infty$. Here the exponents $\alpha$ depend on the coupling coefficients $c_n$ and \EE denotes expectation with respect to the equilibrium measure. This is reminiscent of the conjectured properties of the solutions of the Navier-Stokes equations in the inviscid limit and their accepted relationship with fully developed turbulence. Hence, these simple models illustrate some of the heuristic ideas that have been advanced to characterize turbulence, similar in that respect to the random passive scalar or random Burgers equation, but even simpler and fully solvable.Comment: 32 Page

Uniform generation in trace monoids

We consider the problem of random uniform generation of traces (the elements of a free partially commutative monoid) in light of the uniform measure on the boundary at infinity of the associated monoid. We obtain a product decomposition of the uniform measure at infinity if the trace monoid has several irreducible components-a case where other notions such as Parry measures, are not defined. Random generation algorithms are then examined.Comment: Full version of the paper in MFCS 2015 with the same titl

Navigability is a Robust Property

The Small World phenomenon has inspired researchers across a number of fields. A breakthrough in its understanding was made by Kleinberg who introduced Rank Based Augmentation (RBA): add to each vertex independently an arc to a random destination selected from a carefully crafted probability distribution. Kleinberg proved that RBA makes many networks navigable, i.e., it allows greedy routing to successfully deliver messages between any two vertices in a polylogarithmic number of steps. We prove that navigability is an inherent property of many random networks, arising without coordination, or even independence assumptions

Networks become navigable as nodes move and forget

We propose a dynamical process for network evolution, aiming at explaining the emergence of the small world phenomenon, i.e., the statistical observation that any pair of individuals are linked by a short chain of acquaintances computable by a simple decentralized routing algorithm, known as greedy routing. Previously proposed dynamical processes enabled to demonstrate experimentally (by simulations) that the small world phenomenon can emerge from local dynamics. However, the analysis of greedy routing using the probability distributions arising from these dynamics is quite complex because of mutual dependencies. In contrast, our process enables complete formal analysis. It is based on the combination of two simple processes: a random walk process, and an harmonic forgetting process. Both processes reflect natural behaviors of the individuals, viewed as nodes in the network of inter-individual acquaintances. We prove that, in k-dimensional lattices, the combination of these two processes generates long-range links mutually independently distributed as a k-harmonic distribution. We analyze the performances of greedy routing at the stationary regime of our process, and prove that the expected number of steps for routing from any source to any target in any multidimensional lattice is a polylogarithmic function of the distance between the two nodes in the lattice. Up to our knowledge, these results are the first formal proof that navigability in small worlds can emerge from a dynamical process for network evolution. Our dynamical process can find practical applications to the design of spatial gossip and resource location protocols.Comment: 21 pages, 1 figur

A geometric condition implying energy equality for solutions of 3D Navier-Stokes equation

We prove that every weak solution $u$ to the 3D Navier-Stokes equation that belongs to the class $L^3L^{9/2}$ and \n u belongs to $L^3L^{9/5}$ localy away from a 1/2-H\"{o}lder continuous curve in time satisfies the generalized energy equality. In particular every such solution is suitable.Comment: 10 page