Performance and Methodological Aspects in Positron Emission Tomography

Performance standards for Positron emission tomography (PET) were developed to be able to compare systems from different generations and manufacturers. This resulted in the NEMA methodology in North America and the IEC in Europe. In practices, the NEMA NU 2- 2001 is the method of choice today. These standardized methods allow assessment of the physical performance of new commercial dedicated PET/CT tomographs. The point spread in image formation is one of the factors that blur the image. The phenomenon is often called the partial volume effect. Several methods for correcting for partial volume are under research but no real agreement exists on how to solve it. The influence of the effect varies in different clinical settings and it is likely that new methods are needed to solve this problem. Most of the clinical PET work is done in the field of oncology. The whole body PET combined with a CT is the standard investigation today in oncology. Despite the progress in PET imaging technique visualization, especially quantification of small lesions is a challenge. In addition to partial volume, the movement of the object is a significant source of error. The main causes of movement are respiratory and cardiac motions. Most of the new commercial scanners are in addition to cardiac gating, also capable of respiratory gating and this technique has been used in patients with cancer of the thoracic region and patients being studied for the planning of radiation therapy. For routine cardiac applications such as assessment of viability and perfusion only cardiac gating has been used. However, the new targets such as plaque or molecular imaging of new therapies require better control of the cardiac motion also caused by respiratory motion. To overcome these problems in cardiac work, a dual gating approach has been proposed. In this study we investigated the physical performance of a new whole body PET/CT scanner with NEMA standard, compared methods for partial volume correction in PET studies of the brain and developed and tested a new robust method for dual cardiac-respiratory gated PET with phantom, animal and human data. Results from performance measurements showed the feasibility of the new scanner design in 2D and 3D whole body studies. Partial volume was corrected, but there is no best method among those tested as the correction also depends on the radiotracer and its distribution. New methods need to be developed for proper correction. The dual gating algorithm generated is shown to handle dual-gated data, preserving quantification and clearly eliminating the majority of contraction and respiration movement

DFM(A)- aspects for a fixed electrical attenuator design

The goal of this paper is to describe a complete and extensive prototype design of a fixed electrical attenuator. The paper starts by describing the function and by giving some basic information about the attenuators. After a comprehensive description of the component, the facts of reverse engineering are discussed. The method itself is applied to ease manufacturing and design stages of this component. Information about materials and applied manufacturing technologies are also included in this report. By applying some specified DFMA-aspects the final design turned out to be a potential prototype device to be manufactured and for further analyse.

DFM(A)- aspects for a microwave waveguide ring resonator design

In this research manufacturability analysis is made for an E-plane waveguide ring resonator. About the electrical characteristics of the waveguide ring resonator is discussed. Possibilities to utilize concurrent engineering method both for designing and making manufacturability analysis for MW- and RF-components are discussed. For helping to establish the necessary guidelines for easy manufacturing and assembly of the waveguide ring resonator a specialised DFM(A)-questionnaire is generated. The questionnaire gives also new information for collaborative designing approach in MW-/RF- engineering. The advantages and disadvantages of the concurrent engineering design method are evaluated in the research.

DFM(A)- aspects for a horn antenna design

In this paper aspects of design for manufacturability and assembly (DFMA) are applied to the design of coaxially fed standard gain horn antenna for 1.70 - 2.60 GHz. Possibilities to utilize cross-technological approach method is examined. Methods of DFMA for laser processing are covered and practical design guides and methods are developed. Antenna construction for easy manufacturing and specialized performance is shown. Required dimensions and tolerances are discussed and suitable materials for laser processing are selected.

DFM(A)- aspects for an sma connector design

In this research, manufacturability analysis is made for an SMA connector. Analysis and aspects of applying virtual prototyping for an SMA connector design and manufacturing are also investigated. Special questionnaires for the component and machining are made in order to enable necessary information to ensure DFM(A) –aspects of products. The aspects of easy manufacturing for machining the SMA connector are collected. Material selection is discussed, and manufacturing stages of prototype manufacturing are presented. The main focus of this research is on prototype manufacturing, but also aspects considering volume production are discussed. A special purpose SMA connector is designed for printed circuit board edge mounting.

DFM/DFMA(A) – analysis and aspects of applying systematic engineering for a microwave testfixture design

In this paper, manufacturability analysis and collection of design aspects is made for a microwave test-fixture. Aspects of applying systematic design for a microwave test-fixture design and manufacturing are also analysed. Special questionnaires for the component and machining are made in order to enable necessary information to ensure DFM(A) – aspects of the component. The aspects of easy manufacturing for machining the microwave test-fixture are collected. Material selection is discussed and manufacturing stages of prototype manufacturing are presented.

Pathétique Sonata : a study of musical aspects in subjection of aesthetic aims

This study makes an attempt to capture some of the aesthetic ideas prospering in the latter half of the eighteenth century and investigates in what way these are possibly being manifested in different musical aspects in Beethoven's early work, and most specifically in his eight sonata, often referred to as the Pathétique sonata. Beginning the first chapter with an introduction to aesthetic notions in Beethoven's age, the second chapter is mostly concerned with anecdotes regarding the Pathétique sonata. Further the third chapter exhibits possible influences between Cherubini, Beethoven and Wagner, and the last three chapters treat different musical and aesthetic aspects like Beethoven's relation to the C minor tonality, the German Sturm und Drang movement, and finally some parallels that can be found between literature and music.

Espectrometria de massas com ionização por "electrospray" aplicada ao estudo de espécies inorgânicas e organometálicas

Although electrospray ionization mass spectrometry (ES-MS) has been extensively applied to study organic and biochemical species, it is also specially suitable to study inorganic and organo-metallic species. Such species, even those that are low-volatile or thermo-unstable, can be easily ionized or simply transferred from liquid to gas phase by electrospray. However, chemical transformations frequently occur during the process. This paper discusses the fundamental aspects of electrospray ionization as well as its analytical applicability to inorganic and organo-metallic species in order to spread the technique and make its characteristics more familiar to potential users.

Queijos: aspectos químicos, bioquímicos e microbiológicos

This article presents a brief historical outline of cheese manufacture. Chemical, biochemical and microbiological aspects are presented: the main constituents of curd, the reactions involved in the development of flavour, and the role of micro-organisms and enzymes in the fermentation and maturation processes. A brief description of the characteristics of some cheeses is also given.

Amyloid Beta Precursor Protein: Proper Credit for the Basic Biochemical Properties of the Most Studied Protein in the 21st Century

The amyloid precursor protein (APP) is mainly known for being the precursor of the ß-amyloid peptide, which accumulates in plaques found in the brain of Alzheimer's disease patients. Expression in different tissues and the degree of sequence identity among mammals indicate an essential and non-tissue specific physiological function. APP is anchored to the membrane and displays a single C-terminal intracellular domain and a longer N-terminal extracellular domain. The basic biochemical properties and the scattered data on research, not related to production of beta-amyloid peptide, suggest that the protein and the molecules resulting from APP proteolytic cleavage may act as adhesion factors, enzymes, hormones/neurotransmitters and/or protease inhibitors. APP deserves to be known for its quite notable properties and its physiological role(s).

Biochemical differentiation between Ophidion Barbatum and o. Rochei (Pisces, Ophidiidae)

El gènere Ophidion esta representat al Mediterrani per dues espècies, 0. barbatum L. i O.rochei Müller. Són dues espècies molt similars en aspecte i difícils d'identificar només apartir dels seus caràcters morfològics externs. El treball descriu en primer lloc, i a partir de dades obtingudes per tècniques electroforètiques, alguns marcadors bioquímics que permetendiferenciar les dues espècies. En segon lloc, i a partir del càlcul de la 'Distància Genèticade Nei', es fa una estimació del temps de divergència entre O. barbatum i 0. rochei

Counteracting incentive sensitization in severe alcohol dependence using deep brain stimulation of the nucleus accumbens: clinical and basic science aspects

The ventral striatum / nucleus accumbens has been implicated in the craving for drugs and alcohol which is a major reason for relapse of addicted people. Craving might be induced by drug-related cues. This suggests that disruption of craving-related neural activity in the nucleus accumbens may significantly reduce craving in alcohol-dependent patients. Here we report on preliminary clinical and neurophysiological evidence in three male patients who were treated with high frequency deep brain stimulation of the nucleus accumbens bilaterally. All three had been alcohol dependent for many years, unable to abstain from drinking, and had experienced repeated relapses prior to the stimulation. After the operation, craving was greatly reduced and all three patients were able to abstain from drinking for extended periods of time. Immediately after the operation but prior to connection of the stimulation electrodes to the stimulator, local field potentials were obtained from the externalized cables in two patients while they performed cognitive tasks addressing action monitoring and incentive salience of drug related cues. LFPs in the action monitoring task provided further evidence for a role of the nucleus accumbens in goal-directed behaviors. Importantly, alcohol related cue stimuli in the incentive salience task modulated LFPs even though these cues were presented outside of the attentional focus. This implies that cue-related craving involves the nucleus accumbens and is highly automatic.

Extraction, purification and biochemical characterization of a peroxidase from Copaifera langsdorffii leaves

The aim of this work is to obtain, purify and characterize biochemically a peroxidase from Copaifera langsdorffii leaves (COP). COP was obtained by acetone precipitation followed by ion-exchange chromatography. Purification yielded 3.5% of peroxidase with the purification factor of 46.86. The COP optimum pH is 6.0 and the temperature is 35 ºC. COP was stable in the pH range of 4.5 to 9.3 and at temperatures below 50.0 ºC. The apparent Michaelis-Menten constants (Km) for guaiacol and H2O2 were 0.04 mM and 0.39 mM respectively. Enzyme turnover was 0.075 s-1 for guaiacol and 0.28 s-1 for hydrogen peroxide. Copaifera langsdorffii leaves showed to be a rich source of active peroxidase (COP) during the whole year. COP could replace HRP, the most used peroxidase, in analytical determinations and treatment of industrial effluents at low cost.

Importance of the lipid peroxidation biomarkers and methodological aspects FOR malondialdehyde quantification

Free radicals induce lipid peroxidation, playing an important role in pathological processes. The injury mediated by free radicals can be measured by conjugated dienes, malondialdehyde, 4-hydroxynonenal, and others. However, malondialdehyde has been pointed out as the main product to evaluate lipid peroxidation. Most assays determine malondialdehyde by its reaction with thiobarbituric acid, which can be measured by indirect (spectrometry) and direct methodologies (chromatography). Though there is some controversy among the methodologies, the selective HPLC-based assays provide a more reliable lipid peroxidation measure. This review describes significant aspects about MDA determination, its importance in pathologies and biological samples treatment.

Las habilidades motrices básicas en educación primaria: aspectos de su desarrollo = Key motor skills in primary education: developmental aspects

The physical education curriculum stresses the importance of improving students’ key motor skills. This idea agrees with the contributions of research into motor development concerning the important role these skills play in child development. In order to facilitate this improvement is essential to know the different basic aspects of how these key motor skills evolve as well as the essential factors related to the characteristics and conditions of educational practice