Comparação entre metodologias de controle de qualidade em mamografia digital

The best way to detect breast cancer is by screening mammography. The mammography equipments are dedicated and require a rigorous quality control in order to have a good quality image and to early detect this disease. The digital equipment is relatively new in the market and there isn’t a national rule for quality control for several types of digital detectors. This study has proposed to compare two different tests manuals for quality control provided by the manufacturers of digital mammography equipments, and also compare them to the “European guidelines for quality assurance in breast cancer screening and diagnosis “(2006). The studied equipments were: Senographe 2000D from General Electric (GE) and the Hologic Selenia Lorad. Both were digital mammography equipments, the GE unit presents an indirect digital system and the other presents a direct digital system. Physical parameters of the image have been studied, such as spatial resolution, contrast resolution, noise, signal-tonoise ratio, contrast-to-noise ratio and modulation transfer function. After that, a study of the importance of quality control and the requirement to implement a Quality Assurance Program has been done. One data collection was done to compare those manual, it was done by checking which tests are indicated and the minimum frequency which they should be conducted in accordance with each manufacturer. The tests were performed by different methodologies and the results were compared. The examined tests were: the breast entrance skin dose, mean glandular dose, contrast-to-noise ratio, signal-to-noise ratio, automatic exposure control and automatic control of density, modulation transfer function, equipment resolution, homogeneity and ghost

A pesquisa em televisão digital no Brasil: apontamento sobre o levantamento bibliográfico realizado de 1995-2008 sobre o assunto

In Brazil, the discussion about thereplacement of analog television signals to digitaland its impact on society, in media companies andgovernment began in the 90s. Embryonic steps towardsdigitalisation of the television signal ground were thegovernment of Fernando Collor de Mello (1990-1992),with advances during the government of FernandoHenrique Cardoso (1994-2001) and in the governmentof Luiz Inacio Lula da Silva (2002). The academy startsthe discussion in 1996. This article aims to bring to lightthe results obtained from the survey Digital television:a historical perspective , which received the supportof CNPq for funding of two scholarships for scientifi cinitiation between August 2008 and July 2009. Theproject sought to identify what has been published onthe subject in the fi eld of Social Sciences and from threemacrodescritores (information management, publicpolicy and value chain), providing the li ing of a virtualcollection Zotero bibliographic innovative platform.The mapping serves to show the growing interest anddevelopment of research in the country during theperiod - when the number jumped to three works inthe fi rst seven years (1995-2001) to 198 in the last sevenyears (2002-2008). The research sought to identify themajor authors and works related to digital televisionand published in the country. The survey took intoaccount books, articles published in books, journals,Annals of Compós and Intercom, and dissertations andtheses. Data and refl ections on the survey are containedin this communication.

Televisão digital móvel e portátil

The digital television system adopted by Brazil allows the signal reception of broadcast TV on mobile devices and laptops. This paper aims to analyze issues related to the transmission of free and open TV signals for reception in portable and mobile devices enabled by 1SEG system. We will evaluate the behavior of the user, tv schedule, prime time and experiences in Japan.

A estética da imagem na TV digital

This text reflects on the techniques and the process of image production and its artistic composition to digital television in high defini- tion, whereas the 4:3 and 16:9 formats will exist until shutdown of the analog signal. Within this period, consumers of television programming that have analog receivers will continue to see the images in 4:3 format. That fact determines that the productions in high definition, while capturing images with larger viewing area and have high contrast ratio (>1000:1) must be main- tain the elements of visual storytelling within the smallest area and with the contrast ratio of the analog tv (30:1), at the risk of distorting visually the messages produced by the directors.

Introduction to the Software-defined Radio Approach

Telecommunications have been in constant evolution during past decades. Among the technological innovations, the use of digital technologies is very relevant. Digital communication systems have proven their efficiency and brought a new element in the chain of signal transmitting and receiving, the digital processor. This device offers to new radio equipments the flexibility of a programmable system. Nowadays, the behavior of a communication system can be modified by simply changing its software. This gave rising to a new radio model called Software Defined Radio (or Software-Defined Radio - SDR). In this new model, one moves to the software the task to set radio behavior, leaving to hardware only the implementation of RF front-end. Thus, the radio is no longer static, defined by their circuits and becomes a dynamic element, which may change their operating characteristics, such as bandwidth, modulation, coding rate, even modified during runtime according to software configuration. This article aims to present the use of GNU Radio software, an open-source solution for SDR specific applications, as a tool for development configurable digital radio.

Experimental evidence for the sensitivity of the air-shower radio signal to the longitudinal shower development

We observe a correlation between the slope of radio lateral distributions and the mean muon pseudorapidity of 59 individual cosmic-ray-air-shower events. The radio lateral distributions are measured with LOPES, a digital radio interferometer colocated with the multidetector-air-shower array KASCADE-Grande, which includes a muon-tracking detector. The result proves experimentally that radio measurements are sensitive to the longitudinal development of cosmic-ray air showers. This is one of the main prerequisites for using radio arrays for ultra-high-energy particle physics and astrophysics.

A Unitary Approach to Information and Estimation Theory in Digital Communication Systems

This thesis presents the outcomes of a Ph.D. course in telecommunications engineering. It is focused on the optimization of the physical layer of digital communication systems and it provides innovations for both multi- and single-carrier systems. For the former type we have first addressed the problem of the capacity in presence of several nuisances. Moreover, we have extended the concept of Single Frequency Network to the satellite scenario, and then we have introduced a novel concept in subcarrier data mapping, resulting in a very low PAPR of the OFDM signal. For single carrier systems we have proposed a method to optimize constellation design in presence of a strong distortion, such as the non linear distortion provided by satellites' on board high power amplifier, then we developed a method to calculate the bit/symbol error rate related to a given constellation, achieving an improved accuracy with respect to the traditional Union Bound with no additional complexity. Finally we have designed a low complexity SNR estimator, which saves one-half of multiplication with respect to the ML estimator, and it has similar estimation accuracy.

Performance evaluation of detector for digital radiography

Lo scopo di questo lavoro è la caratterizzazione fisica del flat panel PaxScan4030CB Varian, rivelatore di raggi X impiegato in un ampio spettro di applicazioni cliniche, dalla radiografia generale alla radiologia interventistica. Nell’ambito clinico, al fine di una diagnosi accurata, è necessario avere una buona qualità dell’immagine radiologica mantenendo il più basso livello di dose rilasciata al paziente. Elemento fondamentale per ottenere questo risultato è la scelta del rivelatore di radiazione X, che deve garantire prestazioni fisiche (contrasto, risoluzione spaziale e rumore) adeguati alla specifica procedura. Le metriche oggettive che misurano queste caratteristiche sono SNR (Signal-to-Noise Ratio), MTF (Modulation Transfer Function) ed NPS (Noise Power Spectrum), che insieme contribuiscono alla misura della DQE (Detective Quantum Efficiency), il parametro più completo e adatto a stabilire le performance di un sistema di imaging. L’oggettività di queste misure consente anche di mettere a confronto tra loro diversi sistemi di rivelazione. La misura di questi parametri deve essere effettuata seguendo precisi protocolli di fisica medica, che sono stati applicati al rivelatore PaxScan4030CB presente nel laboratorio del Centro di Coordinamento di Fisica Medica, Policlinico S.Orsola. I risultati ottenuti, conformi a quelli dichiarati dal costruttore, sono stati confrontati con successo con alcuni lavori presenti in letteratura e costituiscono la base necessaria per la verifica di procedure di ottimizzazione dell’immagine radiologica attraverso interventi sul processo di emissione dei raggi X e sul trattamento informatico dell’immagine (Digital Subtraction Angiography).

Performance Tuning Non-Uniform Sampling for Sensitivity Enhancement of Signal-Limited Biological NMR

Non-uniform sampling (NUS) has been established as a route to obtaining true sensitivity enhancements when recording indirect dimensions of decaying signals in the same total experimental time as traditional uniform incrementation of the indirect evolution period. Theory and experiments have shown that NUS can yield up to two-fold improvements in the intrinsic signal-to-noise ratio (SNR) of each dimension, while even conservative protocols can yield 20-40 % improvements in the intrinsic SNR of NMR data. Applications of biological NMR that can benefit from these improvements are emerging, and in this work we develop some practical aspects of applying NUS nD-NMR to studies that approach the traditional detection limit of nD-NMR spectroscopy. Conditions for obtaining high NUS sensitivity enhancements are considered here in the context of enabling H-1,N-15-HSQC experiments on natural abundance protein samples and H-1,C-13-HMBC experiments on a challenging natural product. Through systematic studies we arrive at more precise guidelines to contrast sensitivity enhancements with reduced line shape constraints, and report an alternative sampling density based on a quarter-wave sinusoidal distribution that returns the highest fidelity we have seen to date in line shapes obtained by maximum entropy processing of non-uniformly sampled data.

A Closed-Form Solution for the Optimal Time Evolution of an Exponentially Decaying Signal with Thermal Noise

The signal-to-noise ratio of a monoexponentially decaying signal exhibits a maximum at an evolution time of approximately 1.26 T-2. It has previously been thought that there is no closed-form solution to express this maximum. We report in this note that this maximum can be represented in a specific, analytical closed form in terms of the negative real branch of an inverse function known as the Lambert W function. The Lambert function is finding increasing use in the solution of problems in a variety of areas in the physical sciences. (C) 2014 Wiley Periodicals, Inc.

Communicating Severity of Hazard with the Signal Word on a Safety Sign

An experiment examined five signal words on safety signs for effectiveness at communicating information about severity of a hazard. Perceived severity was rated by 59 college students for the signal words Deadly, Danger, Warning, Caution, and Notice. Results indicated that Deadly communicated the highest ratings for severity. Danger was second. Warning and Caution were tied for third. The lowest ratings were for Notice.

Comparison of Student Versus Employee Test Populations for Warning Sign Research Based on Severity Ratings for Signal Words

Most studies of warning signs involve undergraduate students as subjects. This paper reports a direct comparison of findings from an undergraduate population and an employed population. The 48 employed subjects from this study were compared with 59 undergraduate subjects from a companion study. Subjects from both populations were shown the same signs and asked to rate the severity level connoted by each sign. The signs differed only in signal word. Results for each population indicated that signal word had a highly significant effect on severity ratings. When the two populations were compared for ratings of each signal word, the only significant difference was for Caution. Median ratings of each population were the same: Deadly (4), Danger (3), Warning (2), Caution (1), and Notice (0).

Photonics Crystals: The Future of Microwave Signal Processing

The ability of cryogenic photonic crystals to carry out high performance microwave signal processing operations has been developed into systems that can: rapidly record broadband microwave spectra with fine resolution and high dynamic range; search for patterns in 40 gigabits per second data streams; and communicate via spread- spectrum signals that are well below the noise floor. The basic concepts of the technology and its many applications, along with an overview of university-industry partnerships and the growing photonics industry in Bozeman, will be presented.

TV Signal Delivery to Cable Operators and DTH Platform Operators

The paper discusses new business models of transmission of television programs in the context of definitions of broadcasting and retransmission. Typically the whole process of supplying content to the end user has two stages: a media service provider supplies a signal assigned to a given TV channel to the cable operators and satellite DTH platform operators (dedicated transmission), and cable operators and satellite DTH platform operators transmit this signal to end users. In each stage the signals are encoded and are not available for the general public without the intervention of cable/platform operators. The services relating to the supply and transmission of the content are operated by different business entities: each earns money separately and each uses the content protected by copyright. We should determine how to define the actions of the entity supplying the signal with the TV program directly to the cable/digital platform operator and the actions of the entity providing the end user with the signal. The author criticizes the approach presented in the Chellomedia and Norma rulings, arguing that they lead to a significant level of legal uncertainty, and poses the basic questions concerning the notion of “public” in copyright.