Landau analog levels for dipoles in non-commutative space and phase space - Landau analog levels for dipoles

We investigate the analog of Landau quantization, for a neutral polarized particle in the presence of homogeneous electric and magnetic external fields, in the context of non-commutative quantum mechanics. This particle, possessing electric and magnetic dipole moments, interacts with the fields via the Aharonov-Casher and He-McKellar-Wilkens effects. For this model we obtain the Landau energy spectrum and the radial eigenfunctions of the non-commutative space coordinates and non-commutative phase space coordinates. Also we show that the case of non-commutative phase space can be treated as a special case of the usual non-commutative space coordinates.

Influence of interlayer tunneling on the quantized Hall phases in intentionally disordered multilayer structures

Stability of the quantized Hall phases is studied in weakly coupled multilayers as a function of the interlayer correlations controlled by the interlayer tunneling and by the random variation of the well thicknesses. A strong enough interlayer disorder destroys the symmetry responsible for the quantization of the Hall conductivity, resulting in the breakdown of the quantum Hall effect. A clear difference between the dimensionalities of the metallic and insulating quantum Hall phases is demonstrated. The sharpness of the quantized Hall steps obtained in the coupled multilayers with different degrees of randomization was found consistent with the calculated interlayer tunneling energies. The observed width of the transition between the quantized Hall states in random multilayers is explained in terms of the local fluctuations of the electron density.

Compressibility of electron liquid in the quantized Hall phase of GaAs/AlGaAs multi-layers

Magneto-capacitance was studied in narrow miniband GaAs/AlGaAs superlattices where quasi-two dimensional electrons revealed the integer quantum Hall effect. The interwell tunneling was shown to reduce the effect of the quantization of the density of states on the capacitance of the superlattices. In such case the minimum of the capacitance observed at the filling factor nu = 2 was attributed to the decrease of the electron compressibility due to the formation of the incompressible quantized Hall phase. In accord with the theory this phase was found strongly inhomogeneous. The incompressible fraction of the quantized Hall phase was demonstrated to rapidly disappear with the increasing temperature. (C) 2008 Elsevier B.V. All rights reserved.

The Hilbert space of the Chern-Simons theory on a cylinder: a loop quantum gravity approach

As a laboratory for loop quantum gravity, we consider the canonical quantization of the three-dimensional Chern-Simons theory on a noncompact space with the topology of a cylinder. Working within the loop quantization formalism, we define at the quantum level the constraints appearing in the canonical approach and completely solve them, thus constructing a gauge and diffeomorphism invariant physical Hilbert space for the theory. This space turns out to be infinite dimensional, but separable.

The Gelfand-Kirillov conjecture and Gelfand-Tsetlin modules for finite W-algebras

We address two problems with the structure and representation theory of finite W-algebras associated with general linear Lie algebras. Finite W-algebras can be defined using either Kostant`s Whittaker modules or a quantum Hamiltonian reduction. Our first main result is a proof of the Gelfand-Kirillov conjecture for the skew fields of fractions of finite W-algebras. The second main result is a parameterization of finite families of irreducible Gelfand-Tsetlin modules using Gelfand-Tsetlin subalgebra. As a corollary, we obtain a complete classification of generic irreducible Gelfand-Tsetlin modules for finite W-algebras. (C) 2009 Elsevier Inc. All rights reserved.

Döden i Falun 1750 till 1770 : Gruvhanteringen och miljön i ett jämförande perspektiv

Syftet med denna uppsats är att utröna om risken att avlida i förtid var större i Falun än på tre andra jämnstora orter i Mellansverige med i övrigt likartade miljömässiga förutsättningar, mellan åren 1750 till 1770. Det använda källmaterialet är Tabellverkets folkbokförings- och mortalitetstabeller för åren 1750 till 1770. Dödsfall i miljörelaterade sjukdomar för Falun har jämförts med orterna Mora, Gefle och Hedemora. Miljön i Falun skiljde sig från de andra orterna främst på grund av den massiva exponeringen av svaveldioxid och metallhaltiga partiklar, som förekom som ett resultat av gruvverksamheten och den efterföljande kopparframställningen. Gefle var en tätort med stadens problem medan Mora var ett agrart samhälle och Hedemora var både och. Resultatet visar, att risken att avlida i bröst- och lungrelaterade sjukdomar var signifikant högre i Falun än i Mora och Hedemora. Även i Gävle var risken mindre än i Falun, dock ej lika tydligt, vilket sannolikt är en följd av att Gävle var en tätort, som allmänt gav en högre dödlighet. Även den allmänna risken att avlida i förtid var högre i Falun än för de andra orterna. Undersökningen visar också på den risk, som fanns, att avlida i förtid, som de olika epidemierna gav upphov till och den stora inverkan det får. Medelåldern var högre i Falun än för de andra undersökta orterna men detta förklaras främst och rimligast av demografiska skillnader

Amningsvänlig vård enligt UNICEF/WHOs riktlinjer : Nyförlösta mammors perspektiv : Utvärdering av en empirisk studie

Syftet med denna studie var att beskriva i vilken utsträckning mammor vid ett regionsjukhus i Mellansverige ansåg sig vårdats under förlossnings- och BB-tiden i enlighet med några av UNICEF/WHOs riktlinjer (”Tio steg till lyckad amning”) för en amningsvänlig vård. Syftet var vidare att undersöka vilket samband bakgrundsvariablerna mammans ålder, utbildning och paritet hade med deras upplevelser av vården. Studien ingår som en del i en större undersökning där datainsamlingen har genomförts med hjälp av telefonintervjuer utifrån en enkät då barnet var omkring 9 månader. Resultatet visade att mammorna ansåg sig blivit vårdade i enlighet med riktlinjerna när det gällde steg 4 (att låta barnet suga på mammans bröst inom två timmar efter förlossning), steg 6 (att endast ge tillägg på medicinsk indikation), steg 7 (tillämpa samvård), steg 8 (uppmuntra fri amning), steg 9 (inte ge sug- eller dinappar), steg 10 (uppmuntra till att bilda amningshjälpsgrupper) samt delvis med steg 3 (informera alla gravida om amning och dess fördelar). Mammans ålder var ej relaterat till någon av riktlinjerna, medan paritet var relaterat till steg 3 och utbildningsnivå till steg 7 och 9. Förstföderskor ansåg i högre grad än omföderskor att de fått amningsråd under förlossnings- och BB-tiden. Omföderskor ansåg i större omfattning än förstföderskor att de fått stöd och hjälp vid amningsstund under BB-tiden, dock ej under förlossningstiden. Mammor med lägre utbildningsnivå hade i högre grad varit åtskilda från sina nyfödda barn än de med högre utbildningsnivå. Däremot gav de högutbildade mammorna sina barn napp i högre utsträckning. De statistiskt säkerställda sambanden visade att mammans utbildningsnivå, samt om hon är förstföderska eller omföderska hade en viss betydelse för hur hon upplevde vården.

Bröstcancer : Kvinnors upplevelser och behov av stöd efter radikal mastektomi

Syftet med denna systematiska litteraturstudie var att beskriva de bröstcancerdrabbade kvinnornas upplevelser efter radikal mastektomi och deras behov av stöd efter operationen. Studien baserades på 20 vetenskapliga artiklar med både kvalitativ och kvantitativ ansats. Urvalet av artiklar genomfördes genom att använda Högskolan Dalarnas databaser där olika sökord kombinerades. Även manuell sökning genomfördes. Granskningen av artiklarna utfördes med hjälp av en modifierad granskningsmall. Resultatet visade att en mängd olika reaktioner uppstod efter operationen. Kvinnorna upplevde en negativ bild av sig själva vilket medförde att de inte accepterade sin nya kropp och identitet. Det var även vanligt att de bröstcanceropererade isolerade sig från omgivningen och skylde sin bröstförlust inför andra. Kvinnors bröst var ofta förknippat med sexualitet och när de miste sitt bröst efter mastektomin påverkade det även relationen till partnern. Efter operationen var de bröstcancerdrabbade i stort behov av stöd. Det sociala och emotionella stödet innebar för kvinnorna att de hade någon som lyssnade och stöttade dem. Genom att erbjuda dem informativt stöd upplevde de en större trygghet inför framtiden. Även det praktiska stödet var betydelsefullt för kvinnorna då de fick hjälp av familj och vänner med olika göromål.

Metoder för att främja amning av prematura barn : en systematisk litteraturstudie

Syftet med denna studie var att beskriva vilka metoder som användes på en neonatalavdelning för att främja amningen hos prematura barn. Arbetet är en systematisk litteraturstudie där 15 vetenskapliga artiklar användes. Litteratursökningen gjordes i databaserna Blackwell Synergy, CINAHL, Elin@dalarna, PubMed och Medline. Litteraturgenomgången visade att det fanns ett flertal metoder för att främja amning av prematura barn på neonatalavdelningen. Föräldrarna behöver få hjälp av personalen att skapa sociala band till sitt barn och med att förstå att det är dem som är av största betydelse för barnet. NIDCAP-vård var en omvårdnadsmodell som underlättade för samspelet mellan mor och barn. Mamman behöver ständig uppmuntran av personalen och pappan för att lyckas med sin amning. Studier har visat att känguruvård har positiva effekter på amningen och för att utveckla ett tidigt sugbeteende. Barnets tidiga kontakt vid mammas bröst och att mamman så snart som möjligt efter förlossningen börjar pumpa ur bröstmjölk främjar amningen. Andra metoder som främjar amning är att barnet fått känna doften av mammans mjölk och att mamman fått tillgång till en personlig ”amningsexpert”. Tillmatning med kopp eller användning av amningsnapp var metoder som visade sig öka chansen till amning samt bröstmjölkskonsumtionen hos prematura barn.

Uma fundamentação para sinais e sistemas intervalares

In this work we use Interval Mathematics to establish interval counterparts for the main tools used in digital signal processing. More specifically, the approach developed here is oriented to signals, systems, sampling, quantization, coding and Fourier transforms. A detailed study for some interval arithmetics which handle with complex numbers is provided; they are: complex interval arithmetic (or rectangular), circular complex arithmetic, and interval arithmetic for polar sectors. This lead us to investigate some properties that are relevant for the development of a theory of interval digital signal processing. It is shown that the sets IR and R(C) endowed with any correct arithmetic is not an algebraic field, meaning that those sets do not behave like real and complex numbers. An alternative to the notion of interval complex width is also provided and the Kulisch- Miranker order is used in order to write complex numbers in the interval form enabling operations on endpoints. The use of interval signals and systems is possible thanks to the representation of complex values into floating point systems. That is, if a number x 2 R is not representable in a floating point system F then it is mapped to an interval [x;x], such that x is the largest number in F which is smaller than x and x is the smallest one in F which is greater than x. This interval representation is the starting point for definitions like interval signals and systems which take real or complex values. It provides the extension for notions like: causality, stability, time invariance, homogeneity, additivity and linearity to interval systems. The process of quantization is extended to its interval counterpart. Thereafter the interval versions for: quantization levels, quantization error and encoded signal are provided. It is shown that the interval levels of quantization represent complex quantization levels and the classical quantization error ranges over the interval quantization error. An estimation for the interval quantization error and an interval version for Z-transform (and hence Fourier transform) is provided. Finally, the results of an Matlab implementation is given

Contribuições aos Processos de Clustering com Base em Métricas não-Euclidianas

In this work we present a new clustering method that groups up points of a data set in classes. The method is based in a algorithm to link auxiliary clusters that are obtained using traditional vector quantization techniques. It is described some approaches during the development of the work that are based in measures of distances or dissimilarities (divergence) between the auxiliary clusters. This new method uses only two a priori information, the number of auxiliary clusters Na and a threshold distance dt that will be used to decide about the linkage or not of the auxiliary clusters. The number os classes could be automatically found by the method, that do it based in the chosen threshold distance dt, or it is given as additional information to help in the choice of the correct threshold. Some analysis are made and the results are compared with traditional clustering methods. In this work different dissimilarities metrics are analyzed and a new one is proposed based on the concept of negentropy. Besides grouping points of a set in classes, it is proposed a method to statistical modeling the classes aiming to obtain a expression to the probability of a point to belong to one of the classes. Experiments with several values of Na e dt are made in tests sets and the results are analyzed aiming to study the robustness of the method and to consider heuristics to the choice of the correct threshold. During this work it is explored the aspects of information theory applied to the calculation of the divergences. It will be explored specifically the different measures of information and divergence using the Rényi entropy. The results using the different metrics are compared and commented. The work also has appendix where are exposed real applications using the proposed method

Técnicas neuronais de agrupamentos aplicadas à detecção de anomalias em mamogramas digitais

This work proposes the development of an intelligent system for analysis of digital mammograms, capable to detect and to classify masses and microcalcifications. The digital mammograms will be pre-processed through techniques of digital processing of images with the purpose of adapting the image to the detection system and automatic classification of the existent calcifications in the suckles. The model adopted for the detection and classification of the mammograms uses the neural network of Kohonen by the algorithm Self Organization Map - SOM. The algorithm of Vector quantization, Kmeans it is also used with the same purpose of the SOM. An analysis of the performance of the two algorithms in the automatic classification of digital mammograms is developed. The developed system will aid the radiologist in the diagnosis and accompaniment of the development of abnormalities

Algoritmo SOM com estrutura hierárquica e dinâmica aplicado a compressão de imagens

ln this work the implementation of the SOM (Self Organizing Maps) algorithm or Kohonen neural network is presented in the form of hierarchical structures, applied to the compression of images. The main objective of this approach is to develop an Hierarchical SOM algorithm with static structure and another one with dynamic structure to generate codebooks (books of codes) in the process of the image Vector Quantization (VQ), reducing the time of processing and obtaining a good rate of compression of images with a minimum degradation of the quality in relation to the original image. Both self-organizing neural networks developed here, were denominated HSOM, for static case, and DHSOM, for the dynamic case. ln the first form, the hierarchical structure is previously defined and in the later this structure grows in an automatic way in agreement with heuristic rules that explore the data of the training group without use of external parameters. For the network, the heuristic mIes determine the dynamics of growth, the pruning of ramifications criteria, the flexibility and the size of children maps. The LBO (Linde-Buzo-Oray) algorithm or K-means, one ofthe more used algorithms to develop codebook for Vector Quantization, was used together with the algorithm of Kohonen in its basic form, that is, not hierarchical, as a reference to compare the performance of the algorithms here proposed. A performance analysis between the two hierarchical structures is also accomplished in this work. The efficiency of the proposed processing is verified by the reduction in the complexity computational compared to the traditional algorithms, as well as, through the quantitative analysis of the images reconstructed in function of the parameters: (PSNR) peak signal-to-noise ratio and (MSE) medium squared error

Modulação quantizada para sistemas com codificação wavelet sujeitos ao desvanecimento rayleigh

Wavelet coding is an efficient technique to overcome the multipath fading effects, which are characterized by fluctuations in the intensity of the transmitted signals over wireless channels. Since the wavelet symbols are non-equiprobable, modulation schemes play a significant role in the overall performance of wavelet systems. Thus the development of an efficient design method is crucial to obtain modulation schemes suitable for wavelet systems, principally when these systems employ wavelet encoding matrixes of great dimensions. In this work, it is proposed a design methodology to obtain sub-optimum modulation schemes for wavelet systems over Rayleigh fading channels. In this context, novels signal constellations and quantization schemes are obtained via genetic algorithm and mathematical tools. Numerical results obtained from simulations show that the wavelet-coded systems derived here have very good performance characteristics over fading channels

Contribuições a técnicas de agrupamento e visualização de dados multivariados utilizando mapas auto-organizáveis

Self-organizing maps (SOM) are artificial neural networks widely used in the data mining field, mainly because they constitute a dimensionality reduction technique given the fixed grid of neurons associated with the network. In order to properly the partition and visualize the SOM network, the various methods available in the literature must be applied in a post-processing stage, that consists of inferring, through its neurons, relevant characteristics of the data set. In general, such processing applied to the network neurons, instead of the entire database, reduces the computational costs due to vector quantization. This work proposes a post-processing of the SOM neurons in the input and output spaces, combining visualization techniques with algorithms based on gravitational forces and the search for the shortest path with the greatest reward. Such methods take into account the connection strength between neighbouring neurons and characteristics of pattern density and distances among neurons, both associated with the position that the neurons occupy in the data space after training the network. Thus, the goal consists of defining more clearly the arrangement of the clusters present in the data. Experiments were carried out so as to evaluate the proposed methods using various artificially generated data sets, as well as real world data sets. The results obtained were compared with those from a number of well-known methods existent in the literature