Why Is There So Little Money in Politics?

In this paper, we argue that campaign contributions are not a form of policy-buying, but are rather a form of political participation and consumption. We summarize the data on campaign spending, and show through our descriptive statistics and our econometric analysis that individuals, not special interests, are the main source of campaign contributions. Moreover, we demonstrate that campaign giving is a normal good, dependent upon income, and campaign contributions as a percent of GDP have not risen appreciably in over 100 years: if anything, they have probably fallen. We then show that only one in four studies from the previous literature support the popular notion that contributions buy legislators' votes. Finally, we illustrate that when one controls for unobserved constituent and legislator effects, there is little relationship between money and legislator votes. Thus, the question is not why there is so little money politics, but rather why organized interests give at all. We conclude by offering potential answers to this question.

Improving Low Order, Linear, Positive Spatial Quadratures for the Partial Current Neutron Transport Method

AFIT researchers have developed a new approach to solving Discrete Ordinates equations, which approximate the linear Boltzmann Transport Equation (BTE). The usual approach is von Neumann iteration on the scattering source, which requires repeated sweeps through the spatial-angular grid. Acceptable convergence requires complicated and expensive acceleration schemes. The new approach, Partial-Current Transport (PCT) with Adaptive Distribution Iteration, eliminates scattering source iteration through matrix inversions and a reduced-size global linear algebra problem. It creates the needed matrices directly from the standard spatial quadratures used in the sweeping. Positivity, linearity, and (higher-than-first-order) accuracy are the key desirable qualities with all Discrete Ordinates methods, but all three, according to Lathrop [8], cannot be achieved simultaneously. If a high order accurate, linear method is used, it can produce negative fluxes. Non-linear methods have been developed that are high-order accurate and positive, but these methods are not widely accepted because the BTE is itself a linear equation. Positive, linear methods are available, but are only first-order accurate. The latter can achieve needed accuracy by using optically-thin cells, but with Source Iteration (SI), this requires a fine grid of many cells, hence large computational expense. My new approach is to partition an optically thick cell into 2N identical sub-cells. Each sub-cell is optically thin enough that first-order accurate spatial quadrature methods are sufficiently accurate as well as being linear and positive. The needed matrices are computed as before for a (thinnest) sub-cell. My algorithm combines the matrices for a pair of sub-cells to get the matrices for a single (merged) sub-cell twice as thick. Merging N times yields the matrices for the original cell. This allows PCT to solve the discrete ordinates equations with linearity, positivity, and sufficient accuracy without the high computational cost of increasing the number of cells by a factor of 2N

Convex Hulls of Random Walks

Features related to the perimeter of the convex hull C„ of a random walk in R2 are studied, with particular attention given to its length L„. Bounds on the variance of Ln are obtained to show that, for walks with drift, L„ obeys a strong law. Exponential bounds on the tail probabilities of L„ under special conditions are also obtained. We then develop simple expressions for the expected values of other features of Cn, including the number of faces, the sum of the lengths and squared lengths of the faces, and the number of faces of length t or less

A Priori Bounds on the Euclidean Traveling Salesman

It is proved that there are constants $c_{1}$, $c_{2}$, and $c_{3}$ such that for any set S of n points in the unit square and for any minimum-length tour T of S the sum of squares of the edge lengths of T is bounded by $c_{1} \log n$. (2) the number of edges having length t or greater in T is at most $c_{2}/t^{2}$, and (3) the sum of edge lengths of any subset E of T is bounded by $c_{3}|E|^{1/2}$. The second and third bounds are independent of the number of points in S, as well as their locations. Extensions to dimensions $d \u3e 2$ are also sketched. The presence of the logarithmic term in (1) is engaging because such a term is not needed in the case of the minimum spanning tree and several analogous problems, and, furthermore, we know that there always exists some tour of S (which perhaps does not have minimal length) for which the sum of squared edges is bounded independently of n

Equidistribution of Point Sets for the Traveling Salesman and Related Problems

Given a set S of n points in the unit square [0, 1)2, an optimal traveling salesman tour of S is a tour of S that is of minimum length. A worst-case point set for the Traveling Salesman Problem in the unit square is a point set S(n) whose optimal traveling salesman tour achieves the maximum possible length among all point sets S C [0, 1)2, where JSI = n. An open problem is to determine the structure of S(n). We show that for any rectangle R contained in [0, 1 F, the number of points in S(n) n R is asymptotic to n times the area of R. One corollary of this result is an 0( n log n) approximation algorithm for the worst-case Euclidean TSP. Analogous results are proved for the minimum spanning tree, minimum-weight matching, and rectilinear Steiner minimum tree. These equidistribution theorems are the first results concerning the structure of worst-case point sets like S(n)

On-board demux/demod

To make satellite channels cost competitive with optical cables, the use of small, inexpensive earth stations with reduced antenna size and high powered amplifier (HPA) power will be needed. This will necessitate the use of high e.i.r.p. and gain-to-noise temperature ratio (G/T) multibeam satellites. For a multibeam satellite, onboard switching is required in order to maintain the needed connectivity between beams. This switching function can be realized by either an receive frequency (RF) or a baseband unit. The baseband switching approach has the additional advantage of decoupling the up-link and down-link, thus enabling rate and format conversion as well as improving the link performance. A baseband switching satellite requires the demultiplexing and demodulation of the up-link carriers before they can be switched to their assigned down-link beams. Principles of operation, design and implementation issues of such an onboard demultiplexer/demodulator (bulk demodulator) that was recently built at COMSAT Labs. are discussed

Loss of intranetwork and internetwork resting state functional connections with Alzheimer\u27s disease progression

Alzheimer\u27s disease (AD) is the most common cause of dementia. Much is known concerning AD pathophysiology but our understanding of the disease at the systems level remains incomplete. Previous AD research has used resting-state functional connectivity magnetic resonance imaging (rs-fcMRI) to assess the integrity of functional networks within the brain. Most studies have focused on the default-mode network (DMN), a primary locus of AD pathology. However, other brain regions are inevitably affected with disease progression. We studied rs-fcMRI in five functionally defined brain networks within a large cohort of human participants of either gender (n = 510) that ranged in AD severity from unaffected [clinical dementia rating (CDR) 0] to very mild (CDR 0.5) to mild (CDR 1). We observed loss of correlations within not only the DMN but other networks at CDR 0.5. Within the salience network (SAL), increases were seen between CDR 0 and CDR 0.5. However, at CDR 1, all networks, including SAL, exhibited reduced correlations. Specific networks were preferentially affected at certain CDR stages. In addition, cross-network relations were consistently lost with increasing AD severity. Our results demonstrate that AD is associated with widespread loss of both intranetwork and internetwork correlations. These results provide insight into AD pathophysiology and reinforce an integrative view of the brain\u27s functional organization