Global Fits of the CKM Matrix

We report upon the present status of global fits to Cabibbo-Kobayashi-Maskawa matrix.Comment: 3 pages, 3 figures invited talk presented at EPS conference, Aachen July 17-2

Lighting as a Circadian Rhythm-Entraining and Alertness-Enhancing Stimulus in the Submarine Environment

The human brain can only accommodate a circadian rhythm that closely follows 24 hours. Thus, for a work schedule to meet the brain’s hard-wired requirement, it must employ a 24 hour-based program. However, the 6 hours on, 12 hours off (6/12) submarine watchstanding schedule creates an 18-hour “day” that Submariners must follow. Clearly, the 6/12 schedule categorically fails to meet the brain’s operational design, and no schedule other than one tuned to the brain’s 24 hour rhythm can optimize performance. Providing Submariners with a 24 hour-based watchstanding schedule—combined with effective circadian entrainment techniques using carefully-timed exposure to light—would allow crewmembers to work at the peak of their daily performance cycle and acquire more restorative sleep. In the submarine environment, where access to natural light is absent, electric lighting can play an important role in actively entraining—and closely maintaining—circadian regulation. Another area that is likely to have particular importance in the submarine environment is the potential effect of light to help restore or maintain alertness

A theoretical review of the operation of vibratory stress relief with particular reference to the stabilization of large-scale fabrications

Vibratory stress relief (VSR) is widely used on large welded fabrications to stabilize the structures so that they do not distort during further machining or during operational duty. The level of applied stress achieved during VSR on such structures is only 5–10 per cent of the yield stress. It is, therefore, not obvious how these applied loads come to modify the level of residual stress. It is suggested here that the reason for the success of VSR applied to large fabrications lies (a) in the origin of the residual stresses and (b) in the partial relief of these residual stresses by the initiation of the transformation of retained austenite particles (in the size range from 1 to 25 µm) by the movement of dislocations into positions that are favourable for the nucleation of martensite embryos. The shear deformation associated with the transformation of retained austenite into martensite will reduce the residual stress field to the point where the stability of the structure may be assured

Analytical study of a free-wing/free-trimmer concept

The free-wing/free-trimmer is a NASA-Conceived extension of the free-wing concept intended to permit the use of high-lift flaps. Wing pitching moments are balanced by a smaller, external surface attached by a boom or equivalent structure. The external trimmer is, itself, a miniature free wing, and pitch control of the wing-trimmer assembly is effected through a trailing-edge control tab on the trimmer surface. The longitudinal behavior of representative small free-wing/free-trimmer aircraft was analyzed. Aft-mounted trimmer surfaces are found to be superior to forward trimmers, although the permissible trimmer moment arm is limited, in both cases, by adverse dynamic effects. Aft-trimmer configurations provide excellent gust alleviation and meet fundamental stick-fixed stability criteria while exceeding the lift capabilities of pure free-wing configurations

Modulational instability in a layered Kerr medium: Theory and Experiment

We present the first experimental investigation of modulational instability in a layered Kerr medium. The particularly interesting and appealing feature of our configuration, consisting of alternating glass-air layers, is the piecewise-constant nature of the material properties, which allows a theoretical linear stability analysis leading to a Kronig-Penney equation whose forbidden bands correspond to the modulationally unstable regimes. We find very good {\it quantitative} agreement between theoretical, numerical, and experimental diagnostics of the modulational instability. Because of the periodicity in the evolution variable arising from the layered medium, there are multiple instability regions rather than just one as in the uniform medium.Comment: 4 pages, 4 figures, contains experimental + computational + theoretical results, to appear in Physical Review Letter

Customer mobility and congestion in supermarkets

The analysis and characterization of human mobility using population-level mobility models is important for numerous applications, ranging from the estimation of commuter flows in cities to modeling trade flows between countries. However, almost all of these applications have focused on large spatial scales, which typically range between intra-city scales to inter-country scales. In this paper, we investigate population-level human mobility models on a much smaller spatial scale by using them to estimate customer mobility flow between supermarket zones. We use anonymized, ordered customer-basket data to infer empirical mobility flow in supermarkets, and we apply variants of the gravity and intervening-opportunities models to fit this mobility flow and estimate the flow on unseen data. We find that a doubly-constrained gravity model and an extended radiation model (which is a type of intervening-opportunities model) can successfully estimate 65--70\% of the flow inside supermarkets. Using a gravity model as a case study, we then investigate how to reduce congestion in supermarkets using mobility models. We model each supermarket zone as a queue, and we use a gravity model to identify store layouts with low congestion, which we measure either by the maximum number of visits to a zone or by the total mean queue size. We then use a simulated-annealing algorithm to find store layouts with lower congestion than a supermarket's original layout. In these optimized store layouts, we find that popular zones are often in the perimeter of a store. Our research gives insight both into how customers move in supermarkets and into how retailers can arrange stores to reduce congestion. It also provides a case study of human mobility on small spatial scales