Universal Minimum Heat Leak on Low-Temperature Metallic Electrical Leads

Low-temperature electronic systems require electrical leads which have low electrical resistance to provide bias current I without excessive voltage drop V. But proper cryogenic design also requires high thermal resistance to maintain a minimum heat leak Q from the hot temperature T[hot] to the cold temperature T[cold]. By the Wiedemann-Franz law, these requirements are in direct conflict, and the optimal configuration takes a particularly simple universal approximate form for the common case that T[cold] << T[hot]: Q/I = V = 3.6 kT[hot]/e. This is applied here to the cryopackaging of RSFQ superconducting circuits on a 4K cryocooler, but is equally applicable to other cryogenic systems such as a superconducting sensor array at low and ultra-low temperatures.Comment: Proc. Int. Low Temp. Phys. Conf. (LT24), held in Orlando, FL, Aug. 2005. 2 pages. Minor changes in notation and references in response to reviewer

Optimally edge-colouring outerplanar graphs is in NC

We prove that every outerplanar graph can be optimally edge-coloured in polylogarithmic time using a polynomial number of processors on a parallel random access machine without write conflicts (P-RAM)

Potential Pitfalls for the Purchasing-Power-Parity Puzzle? Sampling and Specification Biases in Mean-Reversion Tests of the Law of One Price

The PPP puzzle is based on empirical evidence that international price differences for individual goods (LOOP) or baskets of goods (PPP) appear highly persistent or even non-stationary. The present consensus is these price differences have a half-life that is of the order of five years at best, and infinity at worst. This seems unreasonable in a world where transportation and transaction costs appear so low as to encourage arbitrage and the convergence of price gaps over much shorter horizons, typically days or weeks. However, current empirics rely on a particular choice of methodology, involving (i) relatively low-frequency monthly, quarterly, or annual data, and (ii) a linear model specification. In fact, these methodological choices are not innocent, and they can be shown to bias analysis to-wards findings of slow convergence and a random walk. Intuitively, if we suspect that the actual adjustment horizon is of the order of days then monthly and annual data cannot be expected to reveal it. If we suspect arbitrage costs are high enough to produce a substantial band of inaction' then a linear model will fail to support convergence if the process spends considerable time random-walking in that band. Thus, when testing for PPP or LOOP, model specification and data sampling should not proceed without consideration of the actual institutional context and logistical framework of markets.

Smoothed and Iterated Bootstrap Confidence Regions for Parameter Vectors

The construction of confidence regions for parameter vectors is a difficult problem in the nonparametric setting, particularly when the sample size is not large. The bootstrap has shown promise in solving this problem, but empirical evidence often indicates that some bootstrap methods have difficulty in maintaining the correct coverage probability, while other methods may be unstable, often resulting in very large confidence regions. One way to improve the performance of a bootstrap confidence region is to restrict the shape of the region in such a way that the error term of an expansion is as small an order as possible. To some extent, this can be achieved by using the bootstrap to construct an ellipsoidal confidence region. This paper studies the effect of using the smoothed and iterated bootstrap methods to construct an ellipsoidal confidence region for a parameter vector. The smoothed estimate is based on a multivariate kernel density estimator. This paper establishes a bandwidth matrix for the smoothed bootstrap procedure that reduces the asymptotic coverage error of the bootstrap percentile method ellipsoidal confidence region. We also provide an analytical adjustment to the nominal level to reduce the computational cost of the iterated bootstrap method. Simulations demonstrate that the methods can be successfully applied in practice

Unemployment Compensation (UC): Eligibility for Students Under State and Federal Laws

[Excerpt] Unemployment Compensation (UC) is a joint federal-state program that provides income support payments to eligible workers who lose their jobs through no fault of their own. Federal law sets out broad guidelines with regard to how the UC program operates and how it should be administered. State laws establish eligibility criteria for who qualifies for the program. In the case of a student who becomes unemployed, eligibility would depend on how their respective state treats students within the UC system. Most states disqualify students from UC benefits while they are in school or disqualify individuals from UC benefits if they leave work to attend school. This is typically due to the presumption that students would be unavailable for work during the time that they are in school. However, exceptions and variations exist from state to state. Many workers who lost their jobs and remain in school may be eligible for UC benefits depending on their circumstances and how their respective states treats students. This report describes these state variations in further detail and how states consider students within the framework of their own unique UC programs

The Gonotrophic-Age Structure of a Population of the \u3ci\u3eSimulium Venustum\u3c/i\u3e Complex (Diptera: Simuliidae) in Algonquin Park, Ontario

Eight techniques for the determination of parity and gonotrophic age were assessed for the obligatorily anautogenous blackfly-species complex, Simulium venustum Say. All females could be age-graded by the presence or absence of dilatations on the ovarioles. However, multiple dilatations on a single ovariole were not found and the Polovodova method could not be used to determine the number of completed gonotrophic cycles. Most females could be age-graded by the appearance of the Malpighian tubules, which undergo morphological changes, probably as a result of a bloodmeal. In some cases, the size of the fat body, the presence of retained (relict), mature ova and the presence of meconium in the gut could be used as accessory age-grading criteria. Insemination status, the volume of the esophageal diverticulum, and the stage of development of the terminal ovarian follicles could not be used to age-grade females. The literature of age-grading in blackflies is reviewed, with special reference to the interpretability of the Polovodova method. Seasonal changes in the gonotrophic-age structure of a population of the S. venustum complex in Algonquin Park, ON, Canada, were examined over two years. The maximal proportion of parous females in the population was 75 and 62% in the two years, respectively. There was weak evidence that parous females were more likely to host seek in the morning and nulliparous females in the afternoon. Parity declined in mid-season, due to the recruitment of newly emerged adults to the population