Rydberg-Rydberg interaction profile from the excitation dynamics of ultracold atoms in lattices

We propose a method for the determination of the interaction potential of Rydberg atoms. Specifically, we consider a laser-driven Rydberg gas confined in a one-dimensional lattice and demonstrate that the Rydberg atom number after a laser excitation cycle as a function of the laser detuning provides a measure for the Rydberg interaction coefficient. With the lattice spacing precisely known, the proposed scheme only relies on the measurement of the number of Rydberg atoms and thus circumvents the necessity to map the interaction potential by varying the interparticle separation.Comment: 4 pages, 2 figure

Spectra and ground states of one- and two-dimensional laser-driven lattices of ultracold Rydberg atoms

We investigate static properties of laser-driven, ultracold Rydberg atoms confined to one- and two-dimensional uniform lattices in the limit of vanishing laser coupling. The spectral structure of square lattices is compared to those of linear chains and similarities as well as differences are pointed out. Furthermore, we employ a method based on elements of graph theory to numerically determine the laser detuning-dependent ground states of various lattice geometries. Ground states for chains as well as square and rectangular lattices are provided and discussed.Comment: 15 pages, 11 Figure

Primary Hemiarthroplasty for Proximal Humeral Fractures in the Elderly: Long-Term Functional Outcome and Social Implications

Background:: Primary shoulder hemiarthroplasty is an established treatment modality for complex fractures of the proximal humerus. Long-term functional outcome is often disappointing. However, little is known about social implications particularly in the elderly. Methods:: A single-institution case series of consecutive geriatric patients (age > 70 years) treated with shoulder hemiarthroplasty for complex fractures of the proximal humerus between 1994 and 1997 was analysed. Postoperative morbidity, long-term function, radiological outcome and social implications were evaluated. Results:: Seventy-seven patients fulfilled the study criteria. Median age at the time of operation was 80 years (range 70-93 years). Systemic and local postoperative complications were observed in 8% including 2 patients (3%) with revision surgery. Postoperative mortality was 1%. Forty-eight patients (62%) were available for follow-up (median 49 months, range 25-80 months), 22 (29%) died from causes unrelated to hemiarthroplasty before follow-up and 7 patients (9%) did not attend follow-up examination. Median Constant-Murley score was 41 points (range 17-77 points). Long-term results concerning pain were satisfying. The Oxford shoulder score ranged from 14 to 40 (median 30). Forty-one patients (85%) still lived in their original environment and managed their daily life independently despite poor shoulder function. Four patients (8%) lived in a retirement home and 3 (6%) in a nursery home. Eighty percent of our patients were still able to use public transportation, do the daily shopping and wash their whole body by themselves. Conclusion:: Most patients managed their daily life independently despite poor shoulder functio

Little evidence for a selective advantage of armour-reduced threespined stickleback individuals in an invertebrate predation experiment

The repeated colonization of freshwater habitats by the ancestrally marine threespined stickleback Gasterosteus aculeatus has been associated with many instances of parallel reduction in armour traits, most notably number of lateral plates. The change in predation regime from marine systems, dominated by gape-limited predators such as piscivorous fishes, to freshwater habitats where grappling invertebrate predators such as insect larvae can dominate the predation regime, has been hypothesized as a driving force. Here we experimentally test the hypothesis that stickleback with reduced armour possess a selective advantage in the face of predation by invertebrates, using a natural population of stickleback that is highly polymorphic for armour traits and a common invertebrate predator from the same location. Our results provide no compelling evidence for selection in this particular predator-prey interaction. We suggest that the postulated selective advantage of low armour in the face of invertebrate predation may not be universa

Invisible Z-Boson Decays at e+e- Colliders

The measurement of the invisible Z-boson decay width at e+e- colliders can be done "indirectly", by subtracting the Z-boson visible partial widths from the Z-boson total width, or "directly", from the process e+e- -> \gamma \nu \bar{\nu}. Both procedures are sensitive to different types of new physics and provide information about the couplings of the neutrinos to the Z-boson. At present, measurements at LEP and CHARM II are capable of constraining the left-handed Z\nu\nu-coupling, 0.45 <~ g_L <~ 0.5, while the right-handed one is only mildly bounded, |g_R| <= 0.2. We show that measurements at a future e+e- linear collider at different center-of-mass energies, \sqrt{s} = MZ and \sqrt{s}s ~ 170 GeV, would translate into a markedly more precise measurement of the Z\nu\nu-couplings. A statistically significant deviation from Standard Model predictions will point toward different new physics mechanisms, depending on whether the discrepancy appears in the direct or the indirect measurement of the invisible Z-width. We discuss some scenarios which illustrate the ability of different invisible Z-boson decay measurements to constrain new physics beyond the Standard Model

Parameterization of a Next Generation In-Vivo Forward Solution Physiological Model of the Human Lower Limb to Simulate and Predict Demographic and Pathology Specific Knee Mechanics

The human knee from a mechanical perspective is arguably one of the more complex of the joints of the human body and for this very reason there are a number of pathological factors that can adversely affect knee function, leading to pain, stiffness and an overall reduced quality of life. To rectify these disease conditions, a variety of intervention techniques exist, all of which are predicated on a thorough understanding of the forces and motions that occur at the knee.Various techniques have been developed to further the understanding of how the knee functions; however, many of these strategies involve time and cost consuming processes in order to assess functionality of the knee. Mathematical modeling is a methodology that uses mathematical equations of motion to solve for forces, or in the case of forward modeling, motions given a known set of forces. Such a model is capable of replicating the functionality of the knee in vivo.One application of such a model is in the context of total knee arthroplasty design. Intended for the restoration of functionality after late stage osteoarthritis, total knee arthroplasty devices are highly dependent on their associated design features and the use of a theoretical model affords the opportunity to test the performance of a device without ever needing to manufacture or implant it.In addition, there are also surgical applications where a mathematical model can test joints that otherwise cannot be evaluated under conventional means. This includes modeling of the healthy knee, as well as various functionality-limiting pathological conditions. Perhaps more importantly is the ability to evaluate different intervention techniques to determine the effectiveness in doing so identify which technique most effectively resolves the pathological issues.Advances to the model have focused on parameterization while contributing to a validated normal knee model, an enhancement on the efficiency of the muscles that drive flexion, facilitated methods to evaluate articular geometries and enhancements providing more realistic physiological motions. The model has also been enhanced to account for demographics, as well as abnormal pathology with additional parameters added to better understand gait mechanics at the knee

Landslides in mountainous regions of Northern Vietnam : causes, protection strategies and the assessment of economic losses

Landslides are a severe problem during the rainy season in many mountainous regions in Asia where forests have been cut so that mountain slopes are destabilized. In this study we analyze the extent and causes of landslides in a mountainous area in Northern Vietnam as viewed from the perspective of the concerned population. We also scrutinize the ideas of these people regarding suitable landslide protection measures and their willingness to contribute to the practical implementation of these measures. It shows that nearly all people living in this area feel highly concerned about the frequent landslide events and that they support the idea of government programs to mitigate the danger of future landslides. We measure the utility they expect from such a landslide protection program, i. e. the social value of such a program, in terms of their willingness to contribute personally to its implementation. Since budgets are tight in these rural areas where subsistence farming still prevails we also analyze the possibilities to measure these expected utility gains in terms of people's willingness to contribute working time instead of money to the proposed landslide protection program. The prospect of employing such an alternative means of contribution is, however, seen rather critical

EPA’S Value Engineering Approach for Gypsum Stack Closure

EPA’s Value Engineering Approach for Gypsum Stack Closure Authors Mr. Michael Ayers - United States - Watershed Geo Mr. Craig Zeller - United States - US EPA Abstract In February 2017, US EPA Region 4 assumed responsibility for water treatment and daily operations for an unlined and open 350-acre gypsum stack located in Pascagoula, Mississippi. The gypsum stack contains approximately 15M cubic yards of phosphogypsum with elevated levels of nutrients and acidic pH. To the immediate east of the facility is one of the most biologically productive estuarine ecosystems in the Gulf of Mexico region. An uncontrolled and untreated release of contact water or leachate from the stack could have catastrophic effects on the Gulf of Mexico and its ecosystem. As a result of these potential risks, the US EPA endeavored to close the gypsum stack as quickly, cost effectively and with minimal impact to the surrounding environment. The two primary closure systems were evaluated and included a soil‐protected geomembrane cover (Traditional Cap) and synthetic turf geomembrane cover (ClosureTurf®). A value engineering study was performed to assess construction costs, operation and maintenance (O&M), environmental impacts, and constructability and ultimately resulted in the selection and installation of ClosureTurf®. The presentation will provide the results of the EPA’s study, key lessons learned from design through installation and discussion of how these same criteria apply to CCR projects