Velocity accelerator for particles

Sheet explosive and metal tube, fitted to the inner periphery of a cam-shaped chamber, accelerate particles to velocities nearing 20 km/sec to evaluate efficacy of spacecraft meteoroid shields

The New Economy: State Governments and Education

The New Economy: State Governments and EducationBureau of Business Researc

High current compensation network for dc logarithmic amplifiers

Circuit voltage output is reduced by voltage equivalent to ampere resistance drop of nonlogarithmic resistances of practical diodes; therefore, output is same as circuit using ideal diode. Circuit applies to meter and electronic recorder movements, and improves performance of radiation detectors and several microbiological monitoring device

Temporary Protected Status: Overview and Current Issues

When civil unrest, violence, or natural disasters erupt in countries around the world, concerns arise over the ability of foreign nationals in the United States from those countries to safely return. Provisions exist in the Immigration and Nationality Act (INA) to offer temporary protected status (TPS) and other forms of relief from removal under specified circumstances. The Secretary of Homeland Security has the discretion to issue TPS for periods of 6 to 18 months and can extend these periods if conditions leading to the designating of TPS do not change. Congress has also provided TPS legislatively. A foreign national who is granted TPS receives a registration document and employment authorization for the duration of a given TPS designation. The United States currently provides TPS to approximately 437,000 foreign nationals from 10 countries: El Salvador, Haiti, Honduras, Nepal, Nicaragua, Somalia, Sudan, South Sudan, Syria, and Yemen. TPS for Guinea, Liberia, and Sierra Leone expired in May 2017, but certain Liberians maintain relief under an administrative mechanism known as Deferred Enforced Departure (DED). Haiti’s TPS designation was extended for an additional six months from July 22, 2017, to January 22, 2018. In September 2017, the Secretary of Homeland Security announced plans to terminate Sudan’s designation on November 2, 2018, while extending South Sudan’s designation by 18 months to May 2, 2019. T here is ongoing debate about whether migrants who have been living in the United States for long periods of time with TPS should receive a pathway to legal permanent resident (LPR) status. Recent policy debates have also focused on whether the Administration should extend TPS for migrants from Central America because of crime and security challenges in the region, as well as for countries in the Caribbean due to recent hurricanes and, in the case of Haiti, ongoing recovery from natural disasters. In addition, Venezuela’s political and economic strife have prompted some U.S. lawmakers to call for its designation for TPS

Some geometry and combinatorics for the S-invariant of ternary cubics

Given a real cubic form f(x,y,z), there is a pseudo-Riemannian metric given by its Hessian matrix, defined on the open subset of R^3 where the Hessian determinant h is non-zero. We determine the full curvature tensor of this metric in terms of h and the S-invariant of f, obtaining in the process various different characterizations of S. Motivated by the case of intersection forms associated with complete intersection threefolds in the product of three projective spaces, we then study ternary cubic forms which arise as follows: we choose positive integers d1, d2, d3, set r = d1 + d2 + d3 - 3, and consider the coefficient F(x,y,z) of H1^d1 H2^d2 H3^d3 in the product (x H1 + y H2 + z H3)^3 (a_1 H1 + b_1 H2 + c_1 H3) ... (a_r H1 + b_r H2 + c_r H3), the a_j, b_j and c_j denoting non-negative real numbers; we assume also that F is non-degenerate. Previous work of the author on sectional curvatures of Kahler moduli suggests a number of combinatorial conjectures concerning the invariants of F. It is proved here for instance that the Hessian determinant, considered as a polynomial in x,y,z and the a_j, b_j, c_j, has only positive coefficients. The same property is also conjectured to hold for the S-invariant; the evidence and background to this conjecture is explained in detail in the paper.Comment: 23 pages, plain Tex, updated and shortened, final versio

Research instrumentation for tornado electromagnetics emissions detection

Instrumentation for receiving, processing, and recording HF/VHF electromagnetic emissions from severe weather activity is described. Both airborne and ground-based instrumentation units are described on system and subsystem levels. Design considerations, design decisions, and the rationale behind the decisions are given. Performance characteristics are summarized and recommendations for improvements are given. The objectives, procedures, and test results of the following are presented: (1) airborne flight test in the Midwest U.S.A. (Spring 1975) and at the Kennedy Space Center, Florida (Summer 1975); (2) ground-based data collected in North Georgia (Summer/Fall 1975); and (3) airborne flight test in the Midwest (late Spring 1976) and at the Kennedy Space Center, Florida (Summer 1976). The Midwest tests concentrated on severe weather with tornadic activity; the Florida and Georgia tests monitored air mass convective thunderstorm characteristics. Supporting ground truth data from weather radars and sferics DF nets are described

Modelling of oedemous limbs and venous ulcers using partial differential equations

BACKGROUND: Oedema, commonly known as tissue swelling, occurs mainly on the leg and the arm. The condition may be associated with a range of causes such as venous diseases, trauma, infection, joint disease and orthopaedic surgery. Oedema is caused by both lymphatic and chronic venous insufficiency, which leads to pooling of blood and fluid in the extremities. This results in swelling, mild redness and scaling of the skin, all of which can culminate in ulceration. METHODS: We present a method to model a wide variety of geometries of limbs affected by oedema and venous ulcers. The shape modelling is based on the PDE method where a set of boundary curves are extracted from 3D scan data and are utilised as boundary conditions to solve a PDE, which provides the geometry of an affected limb. For this work we utilise a mixture of fourth order and sixth order PDEs, the solutions of which enable us to obtain a good representative shape of the limb and associated ulcers in question. RESULTS: A series of examples are discussed demonstrating the capability of the method to produce good representative shapes of limbs by utilising a series of curves extracted from the scan data. In particular we show how the method could be used to model the shape of an arm and a leg with an associated ulcer. CONCLUSION: We show how PDE based shape modelling techniques can be utilised to generate a variety of limb shapes and associated ulcers by means of a series of curves extracted from scan data. We also discuss how the method could be used to manipulate a generic shape of a limb and an associated wound so that the model could be fine-tuned for a particular patient