Lesker PVD75 E-beam/Thermal Evaporator (PVD-02) Standard Operating Procedure

Standard Operating Procedure for the Lesker PVD75 E-beam/Thermal Evaporator (PVD-02) located at the Quattrone Nanofabrication Facility within the Singh Center for Nanotechnology at the University of Pennsylvaniahttps://repository.upenn.edu/scn_sop/1027/thumbnail.jp

Matter and dynamics in closed cosmologies

To systematically analyze the dynamical implications of the matter content in cosmology, we generalize earlier dynamical systems approaches so that perfect fluids with a general barotropic equation of state can be treated. We focus on locally rotationally symmetric Bianchi type IX and Kantowski-Sachs orthogonal perfect fluid models, since such models exhibit a particularly rich dynamical structure and also illustrate typical features of more general cases. For these models, we recast Einstein's field equations into a regular system on a compact state space, which is the basis for our analysis. We prove that models expand from a singularity and recollapse to a singularity when the perfect fluid satisfies the strong energy condition. When the matter source admits Einstein's static model, we present a comprehensive dynamical description, which includes asymptotic behavior, of models in the neighborhood of the Einstein model; these results make earlier claims about ``homoclinic phenomena and chaos'' highly questionable. We also discuss aspects of the global asymptotic dynamics, in particular, we give criteria for the collapse to a singularity, and we describe when models expand forever to a state of infinite dilution; possible initial and final states are analyzed. Numerical investigations complement the analytical results.Comment: 23 pages, 24 figures (compressed), LaTe

New explicit spike solution -- non-local component of the generalized Mixmaster attractor

By applying a standard solution-generating transformation to an arbitrary vacuum Bianchi type II solution, one generates a new solution with spikes commonly observed in numerical simulations. It is conjectured that the spike solution is part of the generalized Mixmaster attractor.Comment: Significantly revised. Colour figures simplified to accommodate non-colour printin

Social factors and the prevalence of social isolation in a population-based adult cohort

Purpose: Social isolation has negative effects on physical and brain health across the lifespan. However, the prevalence of social isolation, specifically with regard to sociodemographic and socioeconomic factors, is not well known. Methods: Database was the Leipzig population-based study of adults (LIFE-Adult Study, n = 10,000). The short form of the Lubben Social Network Scale (LSNS-6) was used to assess social isolation (cutoff < 12 points). Sampling weights were applied to account for differences in sampling fractions. Results: Data were available for 9392 study participants; 51.6% were women, the mean age was 45.2 years (SD = 17.3). The prevalence of social isolation was 12.3% (95% CI 11.6-13.0) across ages 18-79 years. Social isolation was more prevalent in men (13.8%, 95% CI 12.8-14.8) compared to women (10.9%, 95% CI 10.0-11.8; [Formula: see text] (1) = 18.83, p < .001), and it showed an increase with increasing age from 5.4% (95% CI 4.7-6.0) in the youngest age group (18-39 years) to 21.7% (95% CI 19.5-24.0) in the oldest age group (70-79 years; [Formula: see text] (4) = 389.51, p < .001). Prevalence differed largely with regard to socioeconomic status (SES); showing lower prevalence in high SES (7.2%, 95% CI 6.0-8.4) and higher prevalence in low SES (18.6%, 95% CI 16.9-20.3; [Formula: see text] (2) = 115.78; p < .001). Conclusion: More than one in ten individuals in the adult population reported social isolation, and prevalence varied strongly with regard to sociodemographic and socioeconomic factors. Social isolation was particularly frequent in disadvantaged socioeconomic groups. From a public health perspective, effective prevention of and intervention against social isolation should be a desired target as social isolation leads to poor health. Countermeasures should especially take into account the socioeconomic determinants of social isolation, applying a life-course perspective

Quantum-Logic Gate between Two Optical Photons with an Average Efficiency above 40%

Optical qubits uniquely combine information transfer in optical fibers with a good processing capability and are therefore attractive tools for quantum technologies. A large challenge, however, is to overcome the low efficiency of two-qubit logic gates. The experimentally achieved efficiency in an optical controlled NOT (CNOT) gate reached approximately 11% in 2003 and has seen no increase since. Here we report on a new platform that was designed to surpass this long-standing record. The new scheme avoids inherently probabilistic protocols and, instead, combines aspects of two established quantum nonlinear systems: atom-cavity systems and Rydberg electromagnetically induced transparency. We demonstrate a CNOT gate between two optical photons with an average efficiency of 41.7(5)% at a postselected process fidelity of 81(2)%. Moreover, we extend the scheme to a CNOT gate with multiple target qubits and produce entangled states of presently up to five photons. All these achievements are promising and have the potential to advance optical quantum information processing in which almost all advanced protocols would profit from high-efficiency logic gates.Comment: In this revision, we extend the discussion of the efficiency in Sec. IV.C and we add models in appendices B, E, and L-

Dynamics of Bianchi type I elastic spacetimes

We study the global dynamical behavior of spatially homogeneous solutions of the Einstein equations in Bianchi type I symmetry, where we use non-tilted elastic matter as an anisotropic matter model that naturally generalizes perfect fluids. Based on our dynamical systems formulation of the equations we are able to prove that (i) toward the future all solutions isotropize; (ii) toward the initial singularity all solutions display oscillatory behavior; solutions do not converge to Kasner solutions but oscillate between different Kasner states. This behavior is associated with energy condition violation as the singularity is approached.Comment: 28 pages, 11 figure

Conformal regularization of Einstein's field equations

To study asymptotic structures, we regularize Einstein's field equations by means of conformal transformations. The conformal factor is chosen so that it carries a dimensional scale that captures crucial asymptotic features. By choosing a conformal orthonormal frame we obtain a coupled system of differential equations for a set of dimensionless variables, associated with the conformal dimensionless metric, where the variables describe ratios with respect to the chosen asymptotic scale structure. As examples, we describe some explicit choices of conformal factors and coordinates appropriate for the situation of a timelike congruence approaching a singularity. One choice is shown to just slightly modify the so-called Hubble-normalized approach, and one leads to dimensionless first order symmetric hyperbolic equations. We also discuss differences and similarities with other conformal approaches in the literature, as regards, e.g., isotropic singularities.Comment: New title plus corrections and text added. To appear in CQ