U-statistics and random subgraph counts: Multivariate normal approximation via exchangeable pairs and embedding

In a recent paper by the authors, a new approach--called the "embedding method"--was introduced, which allows to make use of exchangeable pairs for normal and multivariate normal approximation with Stein's method in cases where the corresponding couplings do not satisfy a certain linearity condition. The key idea is to embed the problem into a higher dimensional space in such a way that the linearity condition is then satisfied. Here we apply the embedding to U-statistics as well as to subgraph counts in random graphs

Joint Transmit and Receive Filter Optimization for Sub-Nyquist Delay-Doppler Estimation

In this article, a framework is presented for the joint optimization of the analog transmit and receive filter with respect to a parameter estimation problem. At the receiver, conventional signal processing systems restrict the two-sided bandwidth of the analog pre-filter $B$ to the rate of the analog-to-digital converter $f_s$ to comply with the well-known Nyquist-Shannon sampling theorem. In contrast, here we consider a transceiver that by design violates the common paradigm $B\leq f_s$. To this end, at the receiver, we allow for a higher pre-filter bandwidth $B>f_s$ and study the achievable parameter estimation accuracy under a fixed sampling rate when the transmit and receive filter are jointly optimized with respect to the Bayesian Cram\'{e}r-Rao lower bound. For the case of delay-Doppler estimation, we propose to approximate the required Fisher information matrix and solve the transceiver design problem by an alternating optimization algorithm. The presented approach allows us to explore the Pareto-optimal region spanned by transmit and receive filters which are favorable under a weighted mean squared error criterion. We also discuss the computational complexity of the obtained transceiver design by visualizing the resulting ambiguity function. Finally, we verify the performance of the optimized designs by Monte-Carlo simulations of a likelihood-based estimator.Comment: 15 pages, 16 figure

Extending Producer Responsibility: An Evaluation Framework for Product Take-Back Policies

Manufacturers are increasingly being required to adhere to product take-back regulations that require them to manage their products at the end of life. Such regulations seek to internalize products' entire life cycle costs into market prices, with the ultimate objective of reducing their environmental burden. This article provides a framework to evaluate the potential for take-back regulations to actually lead to reduced environmental impacts and to stimulate product design changes. It describes trade-offs associated with several major policy decisions, including whether to hold firms physically or financially responsible for the recovery of their products, when to impose recycling fees, whether to include disposal and hazardous substance bans, and whether to mandate product design features to foster reuse and recycling of components and materials. The framework also addresses policy elements that can significantly affect the cost efficiency and occupational safety hazards of end-of-life product recovery operations. The evaluation framework is illustrated with examples drawn from take-back regulations promulgated in Europe, Japan, and the United States governing waste electrical and electronic equipment (WEEE).

HOXA10 controls osteoblastogenesis by directly activating bone regulatory and phenotypic genes

HOXA10 is necessary for embryonic patterning of skeletal elements, but its function in bone formation beyond this early developmental stage is unknown. Here we show that HOXA10 contributes to osteogenic lineage determination through activation of Runx2 and directly regulates osteoblastic phenotypic genes. In response to bone morphogenic protein BMP2, Hoxa10 is rapidly induced and functions to activate the Runx2 transcription factor essential for bone formation. A functional element with the Hox core motif was characterized for the bone-related Runx2 P1 promoter. HOXA10 also activates other osteogenic genes, including the alkaline phosphatase, osteocalcin, and bone sialoprotein genes, and temporally associates with these target gene promoters during stages of osteoblast differentiation prior to the recruitment of RUNX2. Exogenous expression and small interfering RNA knockdown studies establish that HOXA10 mediates chromatin hyperacetylation and trimethyl histone K4 (H3K4) methylation of these genes, correlating to active transcription. HOXA10 therefore contributes to early expression of osteogenic genes through chromatin remodeling. Importantly, HOXA10 can induce osteoblast genes in Runx2 null cells, providing evidence for a direct role in mediating osteoblast differentiation independent of RUNX2. We propose that HOXA10 activates RUNX2 in mesenchymal cells, contributing to the onset of osteogenesis, and that HOXA10 subsequently supports bone formation by direct regulation of osteoblast phenotypic genes. <br/

Gauged Q-balls

Classical non-topological soliton configurations are considered within the theory of a complex scalar field with a gauged U symmetry. Their existence and stability against dispersion are demonstrated and some of their properties are investigated analytically and numerically. The soliton configuration is such that inside the soliton the local U symmetry is broken, the gauge field becomes massive and for a range of values of the coupling constants the soliton becomes a superconductor pushing the charge to the surface. Furthermore, because of the repulsive Coulomb force, there is a maximum size for these objects, making impossible the existence of Q-matter in bulk form. Also briefly discussed are solitons with fermions in a U gauge theory

Computational implementation of the Kubo formula for the static conductance: application to two-dimensional quantum dots

Kubo formula is used to get the d.c conductance of a statistical ensemble of two-dimensional clusters of the square lattice in the presence of standard diagonal disorder, a uniform magnetic field and random magnetic fluxes. Working within a one-band tight-binding approach the calculation is quite general. The shape of the cluster is rectangular with ideal leads attached to opposite corners. Both geometrical characteristics and physical parameters can be easily selected. The output is just the conductance of a system of given parameters or a statistical ensemble of conductances measured for different disorder realizations.Comment: 14 pages, one table, no figures, RevTeX styl

SBIR/STTR Grants: Application Guidance

Small Business Innovation Research (SBIR)/Small Business Technology Transfer (STTR) grants provide a valuable opportunity to receive non-diluting capital. The process of applying for an SBIR/STTR grant has several steps and can take months to complete. SBIR/STTR proposals take the form of typical grant proposals, except the former are shorter and have a lower requirement for preliminary data. An academic entrepreneur should not expect to receive SBIR/STTR funding on their first attempt at a proposal. There are several common pitfalls during the application process, and careful consideration of these issues can substantially improve an application

Meeting national response time targets for priority 1 incidents in an urban emergency medical services system : more ambulances won’t help

Abstract: Objective: To determine the effect of increased emergency vehicle numbers on response time performance for priority 1 incidents in an urban Emergency Medical Services system using discrete-event computer simulation. Method: A simulation model was created, based on input data from part of the Emergency Medical Services operations in Cape Town. Two different versions of the model were used, one with primary response vehicles and ambulances and one with only ambulances. In both cases the models were run in seven different scenarios. The first scenario used the actual number of emergency vehicles in the real system and in each subsequent scenario vehicle numbers were increased by adding the baseline number to the cumulative total. Results: The model using only ambulances had shorter response times and a greater number of responses meeting national response time targets than models using primary response vehicles and ambulances. In both cases an improvement in response times and the number of responses meeting national response time targets was observed with the first incremental addition of vehicles. After this the improvements rapidly diminished and eventually became negligible with each successive increase in vehicle numbers. The national response time target for urban areas was never met, even with a seven-fold increase in vehicle numbers. Conclusion: This study showed that the addition of emergency vehicles to an urban Emergency Medical Services system improves response times in priority 1 incidents but alone is not capable of the magnitude of response time improvement needed to meet the national response time targets