Multilevel Coding Schemes for Compute-and-Forward with Flexible Decoding

We consider the design of coding schemes for the wireless two-way relaying channel when there is no channel state information at the transmitter. In the spirit of the compute and forward paradigm, we present a multilevel coding scheme that permits computation (or, decoding) of a class of functions at the relay. The function to be computed (or, decoded) is then chosen depending on the channel realization. We define such a class of functions which can be decoded at the relay using the proposed coding scheme and derive rates that are universally achievable over a set of channel gains when this class of functions is used at the relay. We develop our framework with general modulation formats in mind, but numerical results are presented for the case where each node transmits using the QPSK constellation. Numerical results with QPSK show that the flexibility afforded by our proposed scheme results in substantially higher rates than those achievable by always using a fixed function or by adapting the function at the relay but coding over GF(4).Comment: This paper was submitted to IEEE Transactions on Information Theory in July 2011. A shorter version also appeared in the proceedings of the International Symposium on Information Theory in August 2011 without the proof of the main theore

Multilevel Coding Schemes for Compute-and-Forward

We investigate techniques for designing modulation/coding schemes for the wireless two-way relaying channel. The relay is assumed to have perfect channel state information, but the transmitters are assumed to have no channel state information. We consider physical layer network coding based on multilevel coding techniques. Our multilevel coding framework is inspired by the compute-and-forward relaying protocol. Indeed, we show that the framework developed here naturally facilitates decoding of linear combinations of codewords for forwarding by the relay node. We develop our framework with general modulation formats in mind, but numerical results are presented for the case where each node transmits using the QPSK constellation with gray labeling. We focus our discussion on the rates at which the relay may reliably decode linear combinations of codewords transmitted from the end nodes

A discrete integrability test based on multiscale analysis

In this article we present the results obtained applying the multiple scale expansion up to the order \epsilon^6 to a dispersive multilinear class of equations on a square lattice depending on 13 parameters. We show that the integrability conditions given by the multiple scale expansion give rise to 4 nonlinear equations, 3 of which are new, depending at most on 2 parameters and containing integrable sub cases. Moreover at least one sub case provides an example of a new integrable system

Joint Compute and Forward for the Two Way Relay Channel with Spatially Coupled LDPC Codes

We consider the design and analysis of coding schemes for the binary input two way relay channel with erasure noise. We are particularly interested in reliable physical layer network coding in which the relay performs perfect error correction prior to forwarding messages. The best known achievable rates for this problem can be achieved through either decode and forward or compute and forward relaying. We consider a decoding paradigm called joint compute and forward which we numerically show can achieve the best of these rates with a single encoder and decoder. This is accomplished by deriving the exact performance of a message passing decoder based on joint compute and forward for spatially coupled LDPC ensembles.Comment: This paper was submitted to IEEE Global Communications Conference 201

On Modulo-Sum Computation over an Erasure Multiple Access Channel

We study computation of a modulo-sum of two binary source sequences over a two-user erasure multiple access channel. The channel is modeled as a binary-input, erasure multiple access channel, which can be in one of three states - either the channel output is a modulo-sum of the two input symbols, or the channel output equals the input symbol on the first link and an erasure on the second link, or vice versa. The associated state sequence is independent and identically distributed. We develop a new upper bound on the sum-rate by revealing only part of the state sequence to the transmitters. Our coding scheme is based on the compute and forward and the decode and forward techniques. When a (strictly) causal feedback of the channel state is available to the encoders, we show that the modulo-sum capacity is increased. Extensions to the case of lossy reconstruction of the modulo-sum and to channels involving additional states are also treated briefly.Comment: Shorter Version will Appear at ISIT 201

Penempatan La (dan Ac) Serta Lu (dan Lr) dalam Sisitem Periodik Unsur

Sistem Periodik Unsur adalah suatu bentuk pengelompokanunsur-unsur secara sistematis, berdasarkan kemiripan sifat unsur~unsur tersebut sehingga mudah untuk dipelajari. Suatu unsur dalamSistem Periodik Unsur kedudukannya dinyatakan dengan menyebutkanblok. golongan serta periodenya.Sampai saat ini unsur La dan Ac dalam Sistem PeriodikUnsur banyak diletakkan pada golongan I1IB di bawah deret Lantanidaserta Aktinida. JBerdasarkan kemiripan sifat-sifat yang ada sebenarnyaunSUi Lu dan Lr lebib sesuai untuk diletakkan pada golongan lIIB dibawah unsur Sc dan Y. Sifat-sifat terscbut, antara lain: jari-jariatom. potensial iooisasi. titik leIch, keelcktronegatifan. strukturkristal. dan sifat super konduktivitasnya. Sedangkan La dan Lc lebihcepat hila ditempatkan sebagai anggota pertaffia dan deret Lantanidadan aktinid

INFLUENCIA DE LAS ESTRATEGIAS INSTRUCCIONALES BASADAS EN SIMULACIONES SOBRE EL NIVEL DE APRENDIZAJE

El prop\uf3sito de este estudio cuantitativo experimental fue introducir una estrategia instruccional basada en el Aprendizaje por Simulaci\uf3n, con la intenci\uf3n de evaluar su efecto sobre el nivel de aprendizaje de los sujetos participantes. Un t\uf3pico sencillo sobre procesamiento de datos fue utilizado en dos variantes: La primera utiliz\uf3 una metodolog\ueda tradicional de instrucci\uf3n presencial y la segunda se aplicaron herramientas de simulaci\uf3n para suministrar el mismo contenido instruccional. Los participantes fueron asignados a un grupo experimental o a un grupo control y luego de la aplicaci\uf3n de pruebas antes y despu\ue9s de la intervenci\uf3n, los resultados fueron sometidos a un an\ue1lisis estad\uedstico (evaluaci\uf3n de hip\uf3tesis). Seg\ufan los resultados obtenidos, se determino que las herramientas multimedia no demostraron ser estad\uedsticamente significativas en el proceso de aprendizaje. Se plantearon lineamientos sobre las fortalezas y debilidades de la estrategia en cuesti\uf3n. The intention of this quantitative experimental study was to introduce a instruccional strategy based on Learning by Simulation, with the intention of evaluating its effect on the learning level achieved by participants. A topic on data processing was used in two variants: The first one used a traditional methodology or approach for instruction and the second one applied tools based on simulation to deliver the same instruccional content. The randomly selected participants were either assigned to an experimental group or to a control group. After the application of tests before and after the intervention, the results were submitted to a statistical analysis (evaluation of hypothesis). Learning by Simulation did not significantly improve performance. Using the obtained results, strengths and weaknesses of the strategy in question were stated and discussed. Palabras claves: ense\uf1anza universitaria; aprendizaje significativo; rendimiento acad\ue9mico; sistemas de simulaci\uf3n.ABSTRACT INFLUENCE OF INSTRUCCIONAL STRATEGIES BASED ON SIMULATIONS ON THE LEARNING LEVEL The purpose of this study was to introduce a quantitative experimental instructional strategy based Learning by Simulation, with the intention of evaluating its effect on the learning level of the participating subjects. A single topic on data processing was used in two variants: The first used a traditional method of classroom instruction and the second simulation tools were applied to provide the same instructional content. Participants were assigned to an experimental group or a control group and after application of tests before and after the intervention, the results were subjected to statistical analysis (hypothesis testing). According to the results, it was determined that the multimedia tools did not prove statistically significant in the learning process. Guidelines were raised about the strengths and weaknesses of the strategy in question. The intention of This quantitative experimental study introduces WAS to instructional strategy based on Learning by Simulation, With the intention of Evaluating STI effect on the learning level Achieved by Participants. A topic on data processing in two variants WAS USED: The first one or Methodology Used to traditional approach for instruction and the second one based on simulation tools Applied to Deliver the Same instructional content. The randomly selected Were Either Participants Assigned to an experimental group or to a control group. After the application of tests Before and After the intervention, the results Were Submitted to a statistical analysis (evaluation of hypothesis). Learning by Simulation did not Significantly Improve Performance. Obtained Using the results, Strengths and Weaknesses of the strategy in question Were State and discussed. Key words: university education, meaningful learning, academic performance simulation systems

Characteristics of Staphylococcus aureus infections to consider in designing an effective vaccine.

_Staphylococcus aureus_ is a very versatile and adaptable microorganism. It can potentially infect virtually any host tissue. Given the appropriate conditions it can become a life-threatening pathogen, or a commensal colonizer of the nose. Extensive antibiotic use for infection control facilitated the rise of antibiotic resistance, stressing the need for alternate forms of control. Vaccine efforts in other pathogens have proved successful, but so far _S. aureus_ candidate vaccines have not been as effective. Here we review _S. aureus_ factors involved in pathogenesis that could help develop a successful vaccine, like host nasal colonization and immune evasion factors. An effective multicomponent vaccine could incorporate antigenic fragments from several _S. aureus_ proteins, preferably involved in colonization, immune evasion and/or toxicity

Prevalencia y caracterizaci?n molecular de Salmonella spp, en granjas av?colas de postura comercial en el departamento del Tolima

99 P?ginasRecurso Electr?nicoLa Salmonelosis es una de las enfermedades trasmitida por alimentos que afecta con mayor frecuencia a humanos y causa grandes p?rdidas econ?micas en la industria av?cola. Con el objeto de estimar la prevalencia y caracterizar los aislamientos de Salmonella spp., se llev? a cabo un estudio epidemiol?gico de corte transversal en granjas de gallinas ponedoras comerciales localizadas en el departamento del Tolima, Colombia. Para este estudio se muestrearon 15 granjas, en las cuales se tomaron 589 muestras para cultivo microbiol?gico de Salmonella spp, caracterizaci?n bioqu?mica, serotipificaci?n y electroforesis en campo pulsado (PFGE). Se analizaron diferentes variables a nivel de granja para determinar los potenciales factores de riesgo. La prevalencia de Salmonella spp., fue de 33.33% (95%, CI=14 - 53%) en granja, y se aislaron 14 cepas de las 589 muestras analizadas, provenientes de cascara de huevo, alimento y zapatones. El an?lisis de serotipificaci?n permiti? identificar los serotipos S. Enteritidis (n=6) y S. Shannon (n=8). Las variables, producci?n propia de alimento balanceado (OR=24), el almacenamiento del huevo en el galp?n (OR=11.25), la presentaci?n del alimento (OR=7.64) y la estructura del galp?n en guadua (OR=5.24), se asociaron significativamente (p<0.05) con la presencia de Salmonella spp., y constituyen potenciales factores de riesgo para la contaminaci?n de este microorganismo en granja. La t?cnica de electroforesis en campo pulsado mostr? tres diferentes patrones de macro restricci?n con XbaI, correspondientes a dos serovares S. Shannon y S. Enteritidis. Estos resultados indican que la Salmonella spp, puede ser aislada de varias fuentes en granjas de ponedoras comerciales, en la cual la superficie del huevo necesita una atenci?n especial para evitar la contaminaci?n en humanos.ABSTRACT. Salmonellosis is the most frequent foodborne disease causing human disease and severe economic losses in the poultry industry. A cross-sectional study was carried out to estimate the prevalence of Salmonella spp, in laying hens farms located at the Tolima region, Colombia. Fifteen egg-laying hen farms were sampled and a total of 589 samples were cultured for Salmonella spp., isolation. The prevalence of Salmonella spp., was 33.33% (95%, CI=14 - 53%) at the farm level. A total of fourteen isolates were recovered from the egg? shells (57.15%, n=8), followed by feed samples (28.57%, n=4) and environmental (14.29%, n=2) samples. Farm?s practices were significantly (p<0.05) associated with Salmonella spp., and variables such as the own feed mill (OR=24), egg stored on hen houses (OR=11.25), feed form (OR=7.64), and facility?s structure in bamboo (OR=5.24) were identified as potential risk factors for Salmonella contamination. S. Enteritidis (n=6) and S. Shannon (n=8) showed three different XbaI macrorestriction patterns by PFGE. The results indicate that Salmonella spp, could be recovered from various sources in laying-hen farms and egg shell contamination needs special attention to impede it transmission to humans.INTRODUCCION 6 1. REVISION DEL TEMA 14 1.1 SALMONELLA 14 1.2 CARACTER?STICAS DEL G?NERO SALMONELLA 15 1.2.1 Caracter?sticas fenot?picas y bioqu?micas 15 1.2.2 Taxonom?a 16 1.3 DETECCI?N E IDENTIFICACI?N DE SALMONELLA SPP 18 1.3.1 Tipos de muestra para la detecci?n de Salmonella spp., en avicultura 18 1.3.2 Aislamiento bacteriol?gico e identificaci?n 21 1.4 SALMONELLA EN HUMANOS: RELACI?N CON AVES Y PRODUCTOS AV?COLAS 26 1.5 SALMONELLA EN AVES COMERCIALES 30 1.5.1 Patogenia 34 1.5.2 Salmonella en aves del Mundo 37 1.5.3 Salmonella en granjas av?colas en Colombia 40 1.6 FACTORES DE RIESGO PARA SALMONELLA 41 1.7 FACTORES DE RIESGO EN GRANJAS DE POLLOS DE ENGORDE 41 1.8 FACTORES DE RIESGO EN GRANJAS DE GALLINAS PONEDORAS 43 2. ESTUDIO DE CASO: CARACTERIZACI?N DE SALMONELLA EN GRANJAS DE GALLINAS DE POSTURA COMERCIAL EN EL DEPARTAMENTO DEL TOLIMA 46 2.1. ANTECEDENTES 50 2.2 MATERIALES Y M?TODOS 51 2.2.1 Poblaci?n de estudio 51 2.2.2 Estudio y an?lisis estad?stico 52 2.2.3 Toma de muestras 52 2.3 AISLAMIENTO E IDENTIFICACI?N DE SALMONELLA 53 2.3.1 Serotipificaci?n de Salmonella 54 2.4 AN?LISIS DE LAS VARIABLES EPIDEMIOL?GICAS 55 2.5 PRUEBA PILOTO 57 2.5.1 An?lisis de datos 58 2.5.2 Caracterizaci?n molecular 58 2.6 RESULTADOS 59 2.6.1 Salmonella spp., en granjas de postura comercial 59 3. FACTORES DE RIESGO DE SALMONELLA SPP., EN GRANJAS AV?COLAS DE POSTURA COMERCIAL EN EL DEPARTAMENTO DEL TOLIMA.60 3.1 AN?LISIS DE ELECTROFORESIS EN CAMPO PULSADO 61 3.2 DISCUSI?N 64 3.2 DISCUSI?N 64 3.3 CONCLUSIONES 69 4. CONCLUSI?NES GENERALES 71 RECOMENDACIONES 72 REFERENCIAS 73 ANEXOS 9