Towards More Practical Linear Programming-based Techniques for Algorithmic Mechanism Design

R. Lavy and C. Swamy (FOCS 2005, J. ACM 2011) introduced a general method for obtaining truthful-in-expectation mechanisms from linear programming based approximation algorithms. Due to the use of the Ellipsoid method, a direct implementation of the method is unlikely to be efficient in practice. We propose to use the much simpler and usually faster multiplicative weights update method instead. The simplification comes at the cost of slightly weaker approximation and truthfulness guarantees

On Randomized Fictitious Play for Approximating Saddle Points Over Convex Sets

Given two bounded convex sets X\subseteq\RR^m and Y\subseteq\RR^n, specified by membership oracles, and a continuous convex-concave function F:X\times Y\to\RR, we consider the problem of computing an \eps-approximate saddle point, that is, a pair $(x^*,y^*)\in X\times Y$ such that \sup_{y\in Y} F(x^*,y)\le \inf_{x\in X}F(x,y^*)+\eps. Grigoriadis and Khachiyan (1995) gave a simple randomized variant of fictitious play for computing an \eps-approximate saddle point for matrix games, that is, when $F$ is bilinear and the sets $X$ and $Y$ are simplices. In this paper, we extend their method to the general case. In particular, we show that, for functions of constant "width", an \eps-approximate saddle point can be computed using O^*(\frac{(n+m)}{\eps^2}\ln R) random samples from log-concave distributions over the convex sets $X$ and $Y$. It is assumed that $X$ and $Y$ have inscribed balls of radius $1/R$ and circumscribing balls of radius $R$. As a consequence, we obtain a simple randomized polynomial-time algorithm that computes such an approximation faster than known methods for problems with bounded width and when \eps \in (0,1) is a fixed, but arbitrarily small constant. Our main tool for achieving this result is the combination of the randomized fictitious play with the recently developed results on sampling from convex sets

Scattering of Dirac electrons by circular mass barriers: valley filter and resonant scattering

The scattering of two-dimensional (2D) massless Dirac electrons is investigated in the presence of a random array of circular mass barriers. The inverse momentum relaxation time and the Hall factor are calculated and used to obtain parallel and perpendicular resistivity components within linear transport theory. We found a non zero perpendicular resistivity component which has opposite sign for electrons in the different K and K' valleys. This property can be used for valley filter purposes. The total cross-section for scattering on penetrable barriers exhibit resonances due to the presence of quasi-bound states in the barriers that show up as sharp gaps in the cross-section while for Schr\"{o}dinger electrons they appear as peaks.Comment: 10 pages, 11 figure

EAP-CRA for WiMAX, WLAN and 4G LTE Interoperability

Today we are moving into a “post-PC” world! Not many people sit in front of custom built PCs to do their businesses any more. Hand held devices such as iPod Touch, iPhone, Galaxy S3, iPad, Galaxy Tab, Airbook, Notepad etc. are bringing in a new paradigm as to how people use and communicate information. These devices can be thought as a theoretical “black-box”. They are for people who want to use it without wanting to know how they work. Such devices have third generation user interfaces – multi touch, physics and gestures (MPG). They need updates, but the user is not worried of how and where the files are stored. When a new application is installed, the user sees the icon and starts using it. The user is not interested in, what files were installed or where it was installed – there is no file management. The post-PC approach to dealing with software is that it’s discovered on an app store, downloaded with a single touch and deleted with another touch. Updates all come at once from the app store and it all happens behind the scene with minimal user involvement. All this is happening and adopted rapidly because people are able to do a number of things without being restricted to one place. They can download apps, watch movies, listen to news, browse the web etc. while on the move.Griffith Sciences, School of Information and Communication TechnologyFull Tex

Nonreciprocal Localization of Photons

We demonstrate that it is possible to localize photons nonreciprocally in a moving photonic lattice made by spatiotemporally modulating the atomic response, where the dispersion acquires a spectral Doppler shift with respect to the probe direction. A static defect placed in such a moving lattice produces a spatial localization of light in the band gap with a shifting frequency that depends on the direction of incident field with respect to the moving lattice. This phenomenon has an impact not only in photonics but also in broader areas such as condensed matter and acoustics, opening the doors for designing new devices such as compact isolators, circulators, nonreciprocal traps, sensors, unidirectional tunable filters, and possibly even a unidirectional laser

Efficiency measurement of cloud service providers using network data envelopment analysis

An increasing number of organizations and businesses around the world use cloud computing services to improve their performance in the competitive marketplace. However, one of the biggest challenges in using cloud computing services is performance measurement and the selection of the best cloud service providers (CSPs) based on quality of service (QoS) requirements (Duan, 2017). To address this shortcoming in this article we propose a network data envelopment analysis (DEA) method in measuring the efficiency of CSPs. When network dimensions are taken into consideration, a more comprehensive analysis is enabled where divisional efficiency is reflected in overall efficiency estimates. This helps managers and decision makers in organizations to make accurate decisions in selecting cloud services. In the current study, variable returns to scale (VRS), the non-oriented network slacks-based measure (SBM) model and input-oriented and output-oriented SBM models are applied to measure the performance of 18 CSPs. The obtained results show the superiority of the network DEA model and they also demonstrate that the proposed model can evaluate and rank CSPs much better than compared to traditional DEA models

Efficacy of a modified bier�s block in patients undergoing upper limb bone surgery

Background: Intravenous regional block, called the Bier's block, refers to an analgesic technique applied for soft tissue surgeries and closed bone manipulations of the limbs. There are a number of complications in traditional method of block, including pain in tourniquet site, immediate return of pain after tourniquet deflation, wound hemostasis and some others. Objectives: The aim of this study was to assess the outcomes and complications of our new method of blockage. Patients and Methods: In this experimental study, twenty-five patients undergoing hand surgery were prospectively studied. Induced anesthesia was a modifcation of the Bier's block with two concurrent changes including insertion of the intravenous cannula at the antecubital region rather than distal and the proximal anesthetic direction by an elastic band wrapped tightly around the proximal forearm distal to the cannulation site. The pain relief was measured by the verbal descriptive scale at intervals after block, during the operation, after deflation of the tourniquet and one hour after the operation. Results: This study showed the presence of analgesia at surgical and tourniquet sites during the operation in 96 of patients, as well as considerable pain relief at surgical site during one hour after deflation of the tourniquet. Conclusions: The study indicated advantages of this modified Bier's block compared to the traditional one including ability to perform surgery on upper limb bones and considerable pain relief at surgical and tourniquet sites during the operation until one hour thereafter. © 2015, Iranian Society of Regional Anesthesia and Pain Medicine (ISRAPM)

Pengaruh Lama Penyimpanan dan Konsentrasi Filtrat Daun Lidah Buaya (Aloe vera) Terhadap Mutu Buah Tomat (Lycopersicum esculentum)

Pembusukan merupakan salah satu masalah yang ditimbulkan setelah masa panen. Buah tomat akan terus mengalami penurunan mutu selama proses penyimpanan, pencegahan dapat dilakukan dengan pemberian edible coating. Salah satu bahan yang dapat dijadikan edible coating adalah daun lidah buaya. Lidah buaya mengandung senyawa antrakuinon, saponin dan emodin yang berfungsi sebagai antimikroba, antikuman dan antibakteri. Penelitian ini bertujuan untuk mengetahui pengaruh lama penyimpanan dan konsentrasi filtrat daun lidah buaya terhadap susut bobot, intensitas kecacatan, kandungan vitamin C dan pH selama proses penyimpanan dan untuk mengetahui berapakah konsentrasi lidah buaya yang paling efektif sebagai bahan pengawet. Kegiatan penelitian dilakukan melalui True Experimental Research. Tempat dan waktu penelitian dilaksanakan di Laboratorium Kimia Universitas Muhammadiyah Malang yang berlangsung pada tanggal 2 – 11 Agustus 2016. Rancangan penelitian yang digunakan adalah Rancangan Acak Lengkap (RAL) Terdiri dari 2 faktor yaitu lama penyimpanan dan konsentrasi filtrat dengan 3 kali ulangan. Analisis data menggunakan SPSS versi 16 dengan analisis varians satu arah dan uji Duncan pada taraf signifikansi 0,05. Hasil penelitian menunjukkan ada pengaruh lama penyimpanan dan konsentrasi filtrat daun lidah buaya terhadap susut bobot, intensitas kecacatan, dan kandungan vitamin C selama proses penyimpanan. Konsentrasi terbaik untuk perubahan susut bobot, intensitas kecacatan dan kandungan vitamin C terdapat pada konsentrasi 8%. Sedangkan untuk nilai pH tidak memiliki perbedaan pada tiap konsentrasi. Hasil penelitian dikembangkan menjadi media audiovisual materi bioteknologi pelajaran biologi SMA kelas XII