Optimal Service-Based Competition with Heterogeneous Suppliers

We investigate how a competition can be designed to maximize expected profit for a buyer who wishes to allocate demand among a diverse set of suppliers when his profit is dependent on the supplier’s service levels. The candidate suppliers are heterogeneous in their capacities and cost structures, and compete for shares of the buyer’s demand based on their promised service levels. To characterize the optimal competition, we first identify a family of allocation functions that are service maximizing, meaning they can intensify the competition to a point where each supplier provides its maximum feasible service level and the outcome of the competition is a predefined set of demand shares. We show that using a service maximizing allocation function is a necessary condition for solving the buyer’s problem. We then characterize the optimal demand allocation set and, when they are endogenous, the optimal procurement prices. When both demand allocation and procurement prices can be chosen by the buyer, we find that the competition also maximizes supply chain profit. Through a set of numerical examples, we show that the benefit of using this optimal competition design, including its specified demand allocation function and suggested procurement prices, can be significant

A rare complication of radiofrequency treatment for cellulite of the lower leg

Radiofrequency (RF) is increasingly used as an aesthetic treatment for a variety of purposes ranging from the treatment of acne scarring, cellulite correction and skin and soft tissue rejuvenation. The majority of patients experience no complications, and the treatment is therefore also frequently administered by non-medically trained staff. We present a patient, who developed severe 3rd degree burn after RF treatment requiring reconstructive surgery with a split thickness skin graft

SoK: Making Sense of Censorship Resistance Systems

An increasing number of countries implement Internet censorship at different scales and for a variety of reasons. Several censorship resistance systems (CRSs) have emerged to help bypass such blocks. The diversity of the censor’s attack landscape has led to an arms race, leading to a dramatic speed of evolution of CRSs. The inherent complexity of CRSs and the breadth of work in this area makes it hard to contextualize the censor’s capabilities and censorship resistance strategies. To address these challenges, we conducted a comprehensive survey of CRSs-deployed tools as well as those discussed in academic literature-to systematize censorship resistance systems by their threat model and corresponding defenses. To this end, we first sketch a comprehensive attack model to set out the censor’s capabilities, coupled with discussion on the scope of censorship, and the dynamics that influence the censor’s decision. Next, we present an evaluation framework to systematize censorship resistance systems by their security, privacy, performance and deployability properties, and show how these systems map to the attack model. We do this for each of the functional phases that we identify for censorship resistance systems: communication establishment, which involves distribution and retrieval of information necessary for a client to join the censorship resistance system; and conversation, where actual exchange of information takes place. Our evaluation leads us to identify gaps in the literature, question the assumptions at play, and explore possible mitigations

Prediction of pulse-to-pulse intensity fluctuation characteristics of high power ultrafast fiber amplifiers

Cataloged from PDF version of article.We report on the experimental characterization and theoretical prediction of pulse-to-pulse intensity fluctuations, namely, intensity noise, for ultrafast fiber amplifiers. We present a theoretical model with which the intensity noise of a Yb-doped fiber amplifier can be predicted with high accuracy, taking into account seed and pump noise, as well as generation of amplified spontaneous emission. Transfer of pump and seed signal modulations to the amplified output during fiber amplification are investigated thoroughly. Practically, our model enables design and optimization of fiber amplifiers with regards to their intensity noise performance. As a route to reducing noise imparted by pump diodes in a double-clad amplifier, we show the use of multiple, low-power diodes is more beneficial compared to a single, high-power diode due to the largely uncorrelated nature of their individual noise contributions. (C) 2014 AIP Publishing LLC

Performance evaluation of a piezoelectric energy harvester based on flag-flutter

In the last few decades, piezoelectric (PZT) materials have played a vital role in the aerospace industry because of their energy harvesting capability. PZT energy harvesters (PEH) absorb the energy from an operational environment and can transform it into useful energy to drive nano/micro-electronic components. In this research work, a PEH based on the flag-flutter mechanism is presented. This mechanism is based on fluid-structure interaction (FSI). The flag is subjected to the axial airflow in the subsonic wind tunnel. The performance evaluation of the harvester and aeroelastic analysis is investigated numerically and experimentally. A novel solution is presented to extract energy from Limit Cycle Oscillations (LCOs) phenomenon by means of PZT transduction. The PZT patch absorbs the flow-induced structural vibrations and transforms it into electrical energy. Furthermore, the optimal resistance and length of the flag is predicted to maximize the energy harvesting. Different configurations of flag i.e., with Aluminium (Al) patch and PZT patch for flutter mode vibration mode are studied numerically and experimentally. The bifurcation diagram is constructed for the experimental campaign for the flutter instability of a cantilevered flag in subsonic wind-tunnel. Moreover, the flutter boundary conditions are analysed for reduced critical velocity and frequency. The designed PZT energy harvester via flag-flutter mechanism is suitable for energy harvesting in aerospace engineering applications to drive wireless sensors. The maximum output power that can be generated from the designed harvester is 6.72 mW and the optimal resistance is predicted to be 0.33 MΩ

Recovering the state sequence of hidden Markov models using mean-field approximations

Inferring the sequence of states from observations is one of the most fundamental problems in Hidden Markov Models. In statistical physics language, this problem is equivalent to computing the marginals of a one-dimensional model with a random external field. While this task can be accomplished through transfer matrix methods, it becomes quickly intractable when the underlying state space is large. This paper develops several low-complexity approximate algorithms to address this inference problem when the state space becomes large. The new algorithms are based on various mean-field approximations of the transfer matrix. Their performances are studied in detail on a simple realistic model for DNA pyrosequencing.Comment: 43 pages, 41 figure

Addressing Food Insecurity Within New American Communities in Vermont

Food insecurity is defined as not having safe, nutritious, or culturally appropriate foods available, or having limited ability to acquire these foods/uncertainty as to when one can acquire these foods. Reasons for food insecurity can be multifactorial such as language barriers, unfamiliar foods, and limited information about food environments.As a result, many turn to processed and energy- dense foods, contributing to the development of chronic diseases. Food banks and local food shelves provide supplemental food assistance to residents and communities in need. However, with diverse New American populations living within the same community, it is challenging to determine which foods best fit their needs. Vermont has welcomed 535 refugees in the last 4 years. Many of these new Americans currently reside in Winooski and Burlington. This study seeks to address the issues of mental health, food insecurity, access to the food shelf, and food preferences within the New American communities located in Winooski, Vermont.https://scholarworks.uvm.edu/comphp_gallery/1320/thumbnail.jp

Free Versus Pedicled Anterolateral Thigh Flap for Abdominal Wall Reconstruction.

Large full thickness abdominal wall defects following malignancies can be a reconstructive challenge. The purpose of this study was to analyze long-term outcomes and complications following abdominal wall reconstruction using composite antero-lateral thigh (ALT) flaps. The study retrospectively investigated 16 consecutive patients who underwent abdominal wall reconstruction with autologous flap between May 2003 and March 2018. Volumetric flap analysis was used to assess flap atrophy over time, evaluating the role of denervation and reinnervation. The long-term outcome was assessed to compare the two groups (free vs. pedicled ALT flap reconstructions). All flaps successfully covered the defects. We found a significant increase in flap resorption in free flaps when compared to pedicled ones. Abdominal bulging was seen in 3 out of 16 (19%) patients after more than 12 months follow-up, in close correlation with mesh absence. Free flaps were shown to be equally effective as their pedicled counterparts, without significant increase in complication rate