Função materna e a constituição subjetiva na condição de prematuridade

Estudos sobre a relação mãe-bebê revelam que o laço que envolve essa dupla, no caso de nascimento prematuro, apresenta especificidades, sendo necessário investigar o efeito da prematuridade nesta relação, uma vez que pesquisas em diversas áreas mostram que os efeitos desse laço primordial repercutem no desenvolvimento posterior da criança. Nesta perspectiva, esta dissertação trata de uma investigação acerca do exercício da função materna em uma situação crítica que é o nascimento prematuro. Uma das questões específicas da prematuridade encontradas no trabalho com a mãe é a dificuldade de investimento libidinal em uma criança pequena, magra e frágil, devido a sua condição orgânica, que em nada se assemelha ao filho imaginário. A questão é analisada numa perspectiva que articula teoria psicanalítica e prática clínica, colocando em cena as influências recíprocas entre prematuridade, perturbação do laço mãe-bebê, função materna, psicopatologia do bebê e constituição subjetiva. O material clínico constitui-se de fragmentos de estudos de casos articulados ao material teórico, a escuta das mães e observação (leitura) de bebês. Os fragmentos permitem a cada leitor fazer sua própria construção ainda que seja para contestar a autora, pois, como diz Derrida (2002), é necessário desconstruir um conhecimento para haver novas construções, o que corrobora Lacan (1993) ao referir que o saber é sempre não-todo. O interesse em investigar o tema está na possibilidade de reflexões que possam ser úteis ao trabalho de outros profissionais envolvidos com a saúde e o desenvolvimento de bebês e crianças.

Influence of light curing units and fluoride mouthrinse on morphological surface and color stability of a nanofilled composite resin

Composite resin is a dental material susceptible to color change over time which limits the longevity of restorations made with this material. The influence of light curing units and different fluoride mouthrinses on superficial morphology and color stability of a nanofilled composite resin was evaluated. Specimens (N = 150) were prepared and polished. The experimental groups were divided according to the type of light source (halogen and LED) and immersion media (artificial saliva, 0.05% sodium fluoride solution-manipulated, Fluordent Reach, Oral B, Fluorgard). Specimens remained in artificial saliva for 24-h baseline. For 60 days, they were immersed in solutions for 1 min. Color readout was taken at baseline and after 60 days of immersion. Surface morphology was analyzed by Scanning Electron Microscopy (SEM) after 60 days of immersion. Color change data were submitted to two-way Analysis of Variance and Tukey tests (α = 0.05). Surface morphology was qualitatively analyzed. The factor light source presented no significant variability (P = 0.281), the immersion media, significant variability (P < 0.001) and interaction between factors, no significant variability (P = 0.050). According to SEM observations, no difference was noted in the surface of the specimens polymerized by different light sources, irrespective of the immersion medium. It was concluded that the light source did not influence the color stability of composite, irrespective of the immersion media, and among the fluoride solutions analyzed, Fluorgard was the one that promoted the greatest color change, however, this was not clinically perceptible. The immersion media did not influence the morphology of the studied resin. Microsc. Res. Tech. 77:941–946, 2014. © 2014 Wiley Periodicals, Inc.

Compact setup for reflection holography with Bi12TiO 20 crystals

A novel optical setup for imaging through reflection holography with Bi12TiO20 (BTO) sillenite photorefractive crystals is proposed. Aiming a compact, robust and simple optical setup the lensless Denisiuk arrangement was chosen, using a He-Ne red laser as light source. In this setup the holographic medium is placed between the light source and the object. The beam impinging the crystal front face is the reference one, while the light scattered by the surface is the object beam in a holographic recording by diffusion. In order to allow the readout of the diffracted wave only and to keep the setup simplicity a polarizing beam splitter cube (PBS) was positioned at the BTO input. The reference beam is s-polarized (polarization direction perpendicular to the table top) and the crystal. 〈001〉-axis is rotated by an angle γ with respect to the input polarization in order to make the transmitted object beam and the diffracted beam to have orthogonal polarizations. While the transmitted wave is reflected by the PBS at a right angle, the diffracted wave carrying the holographic reconstruction of the object passes through the PBS, being collected by a positive lens in order to form the holographic image at a CCD camera. The holographic recording with the grating vector is parallel to the 〈100〉-axis. An expression for the diffracted wave intensity as a function of γ was derived, and this relation was experimentally investigated. © 2008 American Institute of Physics.

Influence of artificial accelerated ageing on the colour stability of paints used for ocular prosthesis iris painting

Objectives: To evaluate the colour stability of paints used for ocular prosthesis iris painting submitted for accelerated artificial ageing (AAA). Materials and methods: Forty specimens of acrylic resin for sclera (16 x 2 mm) were made and separated into eight groups (n = 10) according to the type of paint (gouache, GP; oil, OP; acrylic AP; and composite resin for characterisation, CR) and the colours used (blue/brown). After drying (72 h), a new layer of colourless acrylic resin was applied and the initial colour readout was performed (Spectrophotometer PCB 6807). New colour readouts were performed after AAA, and Delta E was calculated. Results: Statistical analysis (two-way ANOVA-Bonferroni, p < 0.05) demonstrated that the brown colour showed lower Delta E means in comparison with the blue colour, with statistically significant difference for AP only. Blue colour showed no statistically significant difference with regard to the type of paint used. Brown AP showed lower Delta E than the other groups, with significant difference for OP and GP. GP showed greater alteration in Delta E for the brown colour, being statistically similar only to OP. Conclusions: Only the AP group for brown pigment shows clinically acceptable values for colour stability after AAA.

Color stability of modern composites subjected to different periods of accelerated artificial aging

The aim of this study was to evaluate the color stability of composites subjected to different periods of accelerated artificial aging (AAA). A polytetrafluorethylene matrix (10 x 2 mm) was used to fabricate 24 test specimens of three different composites (n=8): Tetric Ceram (Ivoclar/Vivadent); Filtek P90 and Z250 (3M ESPE), shade A3. After light activation for 20 s (FlashLite 1401), polishing and initial color readout (Spectrophotometer PCB 687; BYK Gardner), the test specimens were subjected to AAA (C-UV; Comexim), in 8-h cycles: 4 h exposure to UV-B rays at 50°C and 4 h condensation at 50°C. At the end of each cycle, color readouts were taken and the test ended when the mean value of ΔE attained a level ≥3.30. Tetric Ceram presented alteration in ΔE equal to 3.33 in the first aging cycle. For Filtek P90 and Z250, two (ΔE=3.60) and four (ΔE=3.42) AAA cycles were necessary. After each cycle, there was a reduction of luminosity in all the samples (ΔL). It was concluded that a short period of AAA was sufficient to promote clinically unacceptable color alteration in composites, and that this alteration was material-dependent.

Primary stability in cementless total hip replacement: measurement techniques and aided-surgery

Primary stability of stems in cementless total hip replacements is recognized to play a critical role for long-term survival and thus for the success of the overall surgical procedure. In Literature, several studies addressed this important issue. Different approaches have been explored aiming to evaluate the extent of stability achieved during surgery. Some of these are in-vitro protocols while other tools are coinceived for the post-operative assessment of prosthesis migration relative to the host bone. In vitro protocols reported in the literature are not exportable to the operating room. Anyway most of them show a good overall accuracy. The RSA, EBRA and the radiographic analysis are currently used to check the healing process of the implanted femur at different follow-ups, evaluating implant migration, occurance of bone resorption or osteolysis at the interface. These methods are important for follow up and clinical study but do not assist the surgeon during implantation. At the time I started my Ph.D Study in Bioengineering, only one study had been undertaken to measure stability intra-operatively. No follow-up was presented to describe further results obtained with that device. In this scenario, it was believed that an instrument that could measure intra-operatively the stability achieved by an implanted stem would consistently improve the rate of success. This instrument should be accurate and should give to the surgeon during implantation a quick answer concerning the stability of the implanted stem. With this aim, an intra-operative device was designed, developed and validated. The device is meant to help the surgeon to decide how much to press-fit the implant. It is essentially made of a torsional load cell, able to measure the extent of torque applied by the surgeon to test primary stability, an angular sensor that measure the relative angular displacement between stem and femur, a rigid connector that enable connecting the device to the stem, and all the electronics for signals conditioning. The device was successfully validated in-vitro, showing a good overall accuracy in discriminating stable from unstable implants. Repeatability tests showed that the device was reliable. A calibration procedure was then performed in order to convert the angular readout into a linear displacement measurement, which is an information clinically relevant and simple to read in real-time by the surgeon. The second study reported in my thesis, concerns the evaluation of the possibility to have predictive information regarding the primary stability of a cementless stem, by measuring the micromotion of the last rasp used by the surgeon to prepare the femoral canal. This information would be really useful to the surgeon, who could check prior to the implantation process if the planned stem size can achieve a sufficient degree of primary stability, under optimal press fitting conditions. An intra-operative tool was developed to this aim. It was derived from a previously validated device, which was adapted for the specific purpose. The device is able to measure the relative micromotion between the femur and the rasp, when a torsional load is applied. An in-vitro protocol was developed and validated on both composite and cadaveric specimens. High correlation was observed between one of the parameters extracted form the acquisitions made on the rasp and the stability of the corresponding stem, when optimally press-fitted by the surgeon. After tuning in-vitro the protocol as in a closed loop, verification was made on two hip patients, confirming the results obtained in-vitro and highlighting the independence of the rasp indicator from the bone quality, anatomy and preserving conditions of the tested specimens, and from the sharpening of the rasp blades. The third study is related to an approach that have been recently explored in the orthopaedic community, but that was already in use in other scientific fields. It is based on the vibration analysis technique. This method has been successfully used to investigate the mechanical properties of the bone and its application to evaluate the extent of fixation of dental implants has been explored, even if its validity in this field is still under discussion. Several studies have been published recently on the stability assessment of hip implants by vibration analysis. The aim of the reported study was to develop and validate a prototype device based on the vibration analysis technique to measure intra-operatively the extent of implant stability. The expected advantages of a vibration-based device are easier clinical use, smaller dimensions and minor overall cost with respect to other devices based on direct micromotion measurement. The prototype developed consists of a piezoelectric exciter connected to the stem and an accelerometer attached to the femur. Preliminary tests were performed on four composite femurs implanted with a conventional stem. The results showed that the input signal was repeatable and the output could be recorded accurately. The fourth study concerns the application of the device based on the vibration analysis technique to several cases, considering both composite and cadaveric specimens. Different degrees of bone quality were tested, as well as different femur anatomies and several levels of press-fitting were considered. The aim of the study was to verify if it is possible to discriminate between stable and quasi-stable implants, because this is the most challenging detection for the surgeon in the operation room. Moreover, it was possible to validate the measurement protocol by comparing the results of the acquisitions made with the vibration-based tool to two reference measurements made by means of a validated technique, and a validated device. The results highlighted that the most sensitive parameter to stability is the shift in resonance frequency of the stem-bone system, showing high correlation with residual micromotion on all the tested specimens. Thus, it seems possible to discriminate between many levels of stability, from the grossly loosened implant, through the quasi-stable implants, to the definitely stable one. Finally, an additional study was performed on a different type of hip prosthesis, which has recently gained great interest thus becoming fairly popular in some countries in the last few years: the hip resurfacing prosthesis. The study was motivated by the following rationale: although bone-prosthesis micromotion is known to influence the stability of total hip replacement, its effect on the outcome of resurfacing implants has not been investigated in-vitro yet, but only clinically. Thus the work was aimed at verifying if it was possible to apply to the resurfacing prosthesis one of the intraoperative devices just validated for the measurement of the micromotion in the resurfacing implants. To do that, a preliminary study was performed in order to evaluate the extent of migration and the typical elastic movement for an epiphyseal prosthesis. An in-vitro procedure was developed to measure micromotions of resurfacing implants. This included a set of in-vitro loading scenarios that covers the range of directions covered by hip resultant forces in the most typical motor-tasks. The applicability of the protocol was assessed on two different commercial designs and on different head sizes. The repeatability and reproducibility were excellent (comparable to the best previously published protocols for standard cemented hip stems). Results showed that the procedure is accurate enough to detect micromotions of the order of few microns. The protocol proposed was thus completely validated. The results of the study demonstrated that the application of an intra-operative device to the resurfacing implants is not necessary, as the typical micromovement associated to this type of prosthesis could be considered negligible and thus not critical for the stabilization process. Concluding, four intra-operative tools have been developed and fully validated during these three years of research activity. The use in the clinical setting was tested for one of the devices, which could be used right now by the surgeon to evaluate the degree of stability achieved through the press-fitting procedure. The tool adapted to be used on the rasp was a good predictor of the stability of the stem. Thus it could be useful for the surgeon while checking if the pre-operative planning was correct. The device based on the vibration technique showed great accuracy, small dimensions, and thus has a great potential to become an instrument appreciated by the surgeon. It still need a clinical evaluation, and must be industrialized as well. The in-vitro tool worked very well, and can be applied for assessing resurfacing implants pre-clinically.

Regulation of SRC-3 localization and dynamics by phosphorylation during ERα-dependent transcriptional activation

Transcription is controlled by promoter-selective transcriptional factors (TFs), which bind to cis-regulatory enhancers elements, termed hormone response elements (HREs), in a specific subset of genes. Regulation by these factors involves either the recruitment of coactivators or corepressors and direct interaction with the basal transcriptional machinery (1). Hormone-activated nuclear receptors (NRs) are well characterized transcriptional factors (2) that bind to the promoters of their target genes and recruit primary and secondary coactivator proteins which possess many enzymatic activities required for gene expression (1,3,4). In the present study, using single-cell high-resolution fluorescent microscopy and high throughput microscopy (HTM) coupled to computational imaging analysis, we investigated transcriptional regulation controlled by the estrogen receptor alpha (ERalpha), in terms of large scale chromatin remodeling and interaction with the associated coactivator SRC-3 (Steroid Receptor Coactivator-3), a member of p160 family (28) primary coactivators. ERalpha is a steroid-dependent transcriptional factor (16) that belongs to the NRs superfamily (2,3) and, in response to the hormone 17-ß estradiol (E2), regulates transcription of distinct target genes involved in development, puberty, and homeostasis (8,16). ERalpha spends most of its lifetime in the nucleus and undergoes a rapid (within minutes) intranuclear redistribution following the addition of either agonist or antagonist (17,18,19). We designed a HeLa cell line (PRL-HeLa), engineered with a chromosomeintegrated reporter gene array (PRL-array) containing multicopy hormone response-binding elements for ERalpha that are derived from the physiological enhancer/promoter region of the prolactin gene. Following GFP-ER transfection of PRL-HeLa cells, we were able to observe in situ ligand dependent (i) recruitment to the array of the receptor and associated coregulators, (ii) chromatin remodeling, and (iii) direct transcriptional readout of the reporter gene. Addition of E2 causes a visible opening (decondensation) of the PRL-array, colocalization of RNA Polymerase II, and transcriptional readout of the reporter gene, detected by mRNA FISH. On the contrary, when cells were treated with an ERalpha antagonist (Tamoxifen or ICI), a dramatic condensation of the PRL-array was observed, displacement of RNA Polymerase II, and complete decreasing in the transcriptional FISH signal. All p160 family coactivators (28) colocalize with ERalpha at the PRL-array. Steroid Receptor Coactivator-3 (SRC-3/AIB1/ACTR/pCIP/RAC3/TRAM1) is a p160 family member and a known oncogenic protein (4,34). SRC-3 is regulated by a variety of posttranslational modifications, including methylation, phosphorylation, acetylation, ubiquitination and sumoylation (4,35). These events have been shown to be important for its interaction with other coactivator proteins and NRs and for its oncogenic potential (37,39). A number of extracellular signaling molecules, like steroid hormones, growth factors and cytokines, induce SRC-3 phosphorylation (40). These actions are mediated by a wide range of kinases, including extracellular-regulated kinase 1 and 2 (ERK1-2), c-Jun N-terminal kinase, p38 MAPK, and IkB kinases (IKKs) (41,42,43). Here, we report SRC-3 to be a nucleocytoplasmic shuttling protein, whose cellular localization is regulated by phosphorylation and interaction with ERalpha. Using a combination of high throughput and fluorescence microscopy, we show that both chemical inhibition (with U0126) and siRNA downregulation of the MAP/ERK1/2 kinase (MEK1/2) pathway induce a cytoplasmic shift in SRC-3 localization, whereas stimulation by EGF signaling enhances its nuclear localization by inducing phosphorylation at T24, S857, and S860, known partecipants in the regulation of SRC-3 activity (39). Accordingly, the cytoplasmic localization of a non-phosphorylatable SRC-3 mutant further supports these results. In the presence of ERalpha, U0126 also dramatically reduces: hormone-dependent colocalization of ERalpha and SRC-3 in the nucleus; formation of ER-SRC-3 coimmunoprecipitation complex in cell lysates; localization of SRC-3 at the ER-targeted prolactin promoter array (PRL-array) and transcriptional activity. Finally, we show that SRC-3 can also function as a cotransporter, facilitating the nuclear-cytoplasmic shuttling of estrogen receptor. While a wealth of studies have revealed the molecular functions of NRs and coregulators, there is a paucity of data on how these functions are spatiotemporally organized in the cellular context. Technically and conceptually, our findings have a new impact upon evaluating gene transcriptional control and mechanisms of action of gene regulators.

Applications of High Speed Configurable Logic Devices in Modern Particle Physics Experiments

Several activities were conducted during my PhD activity. For the NEMO experiment a collaboration between the INFN/University groups of Catania and Bologna led to the development and production of a mixed signal acquisition board for the Nemo Km3 telescope. The research concerned the feasibility study for a different acquisition technique quite far from that adopted in the NEMO Phase 1 telescope. The DAQ board that we realized exploits the LIRA06 front-end chip for the analog acquisition of anodic an dynodic sources of a PMT (Photo-Multiplier Tube). The low-power analog acquisition allows to sample contemporaneously multiple channels of the PMT at different gain factors in order to increase the signal response linearity over a wider dynamic range. Also the auto triggering and self-event-classification features help to improve the acquisition performance and the knowledge on the neutrino event. A fully functional interface towards the first level data concentrator, the Floor Control Module, has been integrated as well on the board, and a specific firmware has been realized to comply with the present communication protocols. This stage of the project foresees the use of an FPGA, a high speed configurable device, to provide the board with a flexible digital logic control core. After the validation of the whole front-end architecture this feature would be probably integrated in a common mixed-signal ASIC (Application Specific Integrated Circuit). The volatile nature of the configuration memory of the FPGA implied the integration of a flash ISP (In System Programming) memory and a smart architecture for a safe remote reconfiguration of it. All the integrated features of the board have been tested. At the Catania laboratory the behavior of the LIRA chip has been investigated in the digital environment of the DAQ board and we succeeded in driving the acquisition with the FPGA. The PMT pulses generated with an arbitrary waveform generator were correctly triggered and acquired by the analog chip, and successively they were digitized by the on board ADC under the supervision of the FPGA. For the communication towards the data concentrator a test bench has been realized in Bologna where, thanks to a lending of the Roma University and INFN, a full readout chain equivalent to that present in the NEMO phase-1 was installed. These tests showed a good behavior of the digital electronic that was able to receive and to execute command imparted by the PC console and to answer back with a reply. The remotely configurable logic behaved well too and demonstrated, at least in principle, the validity of this technique. A new prototype board is now under development at the Catania laboratory as an evolution of the one described above. This board is going to be deployed within the NEMO Phase-2 tower in one of its floors dedicated to new front-end proposals. This board will integrate a new analog acquisition chip called SAS (Smart Auto-triggering Sampler) introducing thus a new analog front-end but inheriting most of the digital logic present in the current DAQ board discussed in this thesis. For what concern the activity on high-resolution vertex detectors, I worked within the SLIM5 collaboration for the characterization of a MAPS (Monolithic Active Pixel Sensor) device called APSEL-4D. The mentioned chip is a matrix of 4096 active pixel sensors with deep N-well implantations meant for charge collection and to shield the analog electronics from digital noise. The chip integrates the full-custom sensors matrix and the sparsifification/readout logic realized with standard-cells in STM CMOS technology 130 nm. For the chip characterization a test-beam has been set up on the 12 GeV PS (Proton Synchrotron) line facility at CERN of Geneva (CH). The collaboration prepared a silicon strip telescope and a DAQ system (hardware and software) for data acquisition and control of the telescope that allowed to store about 90 million events in 7 equivalent days of live-time of the beam. My activities concerned basically the realization of a firmware interface towards and from the MAPS chip in order to integrate it on the general DAQ system. Thereafter I worked on the DAQ software to implement on it a proper Slow Control interface of the APSEL4D. Several APSEL4D chips with different thinning have been tested during the test beam. Those with 100 and 300 um presented an overall efficiency of about 90% imparting a threshold of 450 electrons. The test-beam allowed to estimate also the resolution of the pixel sensor providing good results consistent with the pitch/sqrt(12) formula. The MAPS intrinsic resolution has been extracted from the width of the residual plot taking into account the multiple scattering effect.

Molecular architecture of fur binding to iron-induced and - repressed genes in Helicobacter pylori

The ferric uptake regulator protein Fur regulates iron-dependent gene expression in bacteria. In the human pathogen Helicobacter pylori, Fur has been shown to regulate iron-induced and iron-repressed genes. Herein we investigate the molecular mechanisms that control this differential iron-responsive Fur regulation. Hydroxyl radical footprinting showed that Fur has different binding architectures, which characterize distinct operator typologies. On operators recognized with higher affinity by holo-Fur, the protein binds to a continuous AT-rich stretch of about 20 bp, displaying an extended protection pattern. This is indicative of protein wrapping around the DNA helix. DNA binding interference assays with the minor groove binding drug distamycin A, point out that the recognition of the holo-operators occurs through the minor groove of the DNA. By contrast, on the apo-operators, Fur binds primarily to thymine dimers within a newly identified TCATTn10TT consensus element, indicative of Fur binding to one side of the DNA, in the major groove of the double helix. Reconstitution of the TCATTn10TT motif within a holo-operator results in a feature binding swap from an holo-Fur- to an apo-Fur-recognized operator, affecting both affinity and binding architecture of Fur, and conferring apo-Fur repression features in vivo. Size exclusion chromatography indicated that Fur is a dimer in solution. However, in the presence of divalent metal ions the protein is able to multimerize. Accordingly, apo-Fur binds DNA as a dimer in gel shift assays, while in presence of iron, higher order complexes are formed. Stoichiometric Ferguson analysis indicates that these complexes correspond to one or two Fur tetramers, each bound to an operator element. Together these data suggest that the apo- and holo-Fur repression mechanisms apparently rely on two distinctive modes of operator-recognition, involving respectively the readout of a specific nucleotide consensus motif in the major groove for apo-operators, and the recognition of AT-rich stretches in the minor groove for holo-operators, whereas the iron-responsive binding affinity is controlled through metal-dependent shaping of the protein structure in order to match preferentially the major or the minor groove.

A hybrid technology for parallel recording of single ion channels

Hybrid technologies, thanks to the convergence of integrated microelectronic devices and new class of microfluidic structures could open new perspectives to the way how nanoscale events are discovered, monitored and controlled. The key point of this thesis is to evaluate the impact of such an approach into applications of ion-channel High Throughput Screening (HTS)platforms. This approach offers promising opportunities for the development of new classes of sensitive, reliable and cheap sensors. There are numerous advantages of embedding microelectronic readout structures strictly coupled to sensing elements. On the one hand the signal-to-noise-ratio is increased as a result of scaling. On the other, the readout miniaturization allows organization of sensors into arrays, increasing the capability of the platform in terms of number of acquired data, as required in the HTS approach, to improve sensing accuracy and reliabiity. However, accurate interface design is required to establish efficient communication between ionic-based and electronic-based signals. The work made in this thesis will show a first example of a complete parallel readout system with single ion channel resolution, using a compact and scalable hybrid architecture suitable to be interfaced to large array of sensors, ensuring simultaneous signal recording and smart control of the signal-to-noise ratio and bandwidth trade off. More specifically, an array of microfluidic polymer structures, hosting artificial lipid bilayers blocks where single ion channel pores are embededed, is coupled with an array of ultra-low noise current amplifiers for signal amplification and data processing. As demonstrating working example, the platform was used to acquire ultra small currents derived by single non-covalent molecular binding between alpha-hemolysin pores and beta-cyclodextrin molecules in artificial lipid membranes.

Aufbau und Simulation des KAOS-Spektrometers für Koinzidenzmessungen in der assoziierten Kaonproduktion

Mit der Erweiterung des Elektronenbeschleunigers MAMI um eine dritte Stufe ist es möglich geworden, am Institut für Kernphysik Teilchen mit offener Strangeness zu produzieren. Für deren Nachweis ist die Drei-Spektrometeranlage der Kollaboration A1 um das von der GSI in Darmstadt übernommene KAOS-Spektrometer erweitert worden. Untersucht wird damit die elementare Reaktion p(e,e' K+)Lambda/Sigma0 wobei das auslaufende Elektron und das Kaon nachgewiesen werden müssen. Wird als Target nicht Wasserstoff verwendet, besteht die Möglichkeit dass sich ein Hyperkern bildet. Spektroskopische Untersuchungen an diesen bieten die Möglichkeit das Potential von Hyperonen in Atomkernen und die Hyperon-Nukleon-Wechselwirkung zu untersuchen. Aufgrund der hervorragenden Strahlqualität bei der Elektroproduktion können hier Massenauflösungen von einigen hundert keV/c² erreicht werden. Mit Hilfe von GEANT4 wurden die Detektoren und die Abbildungseigenschaften des Spektrometers simuliert. Geeignete Ereignisgeneratoren wurden implementiert. Es wurde untersucht, wie mögliche Treffermuster in den Detektoren aussehen, die von einem Trigger auf FPGA-Basis selektiert werden müssen. Ebenso konnte hieraus eine erste Abbildung der Spurkoordinaten auf die Targetkoordinaten und den Teilchenimpuls gewonnen werden. Für das Hyperkernprogramm muss KAOS unter 0° Vorwärtsrichung betrieben werden und der Primärstrahl mit Hilfe einer Schikane durch den Dipol gelenkt werden. Die Simulation zeigt hier eine nur moderate Erhöhung der Strahlenbelastung, vor allem im Bereich des Strahlfängers. Somit ist es möglich, KAOS als doppelseitiges Spektrometer in der Spektrometerhalle zu betreiben. Im Rahmen dieser Arbeit wurden die für sämtliche Detektoren nötige Auslese- und Steuerungselektronik in das vorhandene Datenerfassungssystem und das Steuerungssystem eingebunden. In zwei Strahlzeiten im Herbst 2008 wurden Kaonen im Winkelbereich von 20°-40° mit Impulsen zwischen 400MeV/c und 600MeV/c nachgewiesen. Die aus der Simulation gewonnenen Daten zum Trigger und zur Abbildung kamen zum Einsatz. Es konnte die für eine gute Teilchenidentifikation nötige Zeitauflösung von ca. 1ns FWHM erreicht werden. Die erreichte Winkel- und Impulsauflösung war ausreichend um Lambda und Sigma0-Hyperonen im Spektrum der fehlenden Masse leicht trennen zu können.

Bestimmung der fehlenden transversalen Energie auf der ersten Triggerstufe beim ATLAS-Experiment und Optimierung der Triggerselektion von supersymmetrischen Ereignissen

Das Standardmodell der Teilchenphysik, das drei der vier fundamentalen Wechselwirkungen beschreibt, stimmt bisher sehr gut mit den Messergebnissen der Experimente am CERN, dem Fermilab und anderen Forschungseinrichtungen überein. rnAllerdings können im Rahmen dieses Modells nicht alle Fragen der Teilchenphysik beantwortet werden. So lässt sich z.B. die vierte fundamentale Kraft, die Gravitation, nicht in das Standardmodell einbauen.rnDarüber hinaus hat das Standardmodell auch keinen Kandidaten für dunkle Materie, die nach kosmologischen Messungen etwa 25 % unseres Universum ausmacht.rnAls eine der vielversprechendsten Lösungen für diese offenen Fragen wird die Supersymmetrie angesehen, die eine Symmetrie zwischen Fermionen und Bosonen einführt. rnAus diesem Modell ergeben sich sogenannte supersymmetrische Teilchen, denen jeweils ein Standardmodell-Teilchen als Partner zugeordnet sind.rnEin mögliches Modell dieser Symmetrie ist das R-Paritätserhaltende mSUGRA-Modell, falls Supersymmetrie in der Natur realisiert ist.rnIn diesem Modell ist das leichteste supersymmetrische Teilchen (LSP) neutral und schwach wechselwirkend, sodass es nicht direkt im Detektor nachgewiesen werden kann, sondern indirekt über die vom LSP fortgetragene Energie, die fehlende transversale Energie (etmiss), nachgewiesen werden muss.rnrnDas ATLAS-Experiment wird 2010 mit Hilfe des pp-Beschleunigers LHC mit einer Schwerpunktenergie von sqrt(s)=7-10 TeV mit einer Luminosität von 10^32 #/(cm^2*s) mit der Suche nach neuer Physik starten.rnDurch die sehr hohe Datenrate, resultierend aus den etwa 10^8 Auslesekanälen des ATLAS-Detektors bei einer Bunchcrossingrate von 40 MHz, wird ein Triggersystem benötigt, um die zu speichernde Datenmenge zu reduzieren.rnDabei muss ein Kompromiss zwischen der verfügbaren Triggerrate und einer sehr hohen Triggereffizienz für die interessanten Ereignisse geschlossen werden, da etwa nur jedes 10^8-te Ereignisse für die Suche nach neuer Physik interessant ist.rnZur Erfüllung der Anforderungen an das Triggersystem wird im Experiment ein dreistufiges System verwendet, bei dem auf der ersten Triggerstufe mit Abstand die höchste Datenreduktion stattfindet.rnrnIm Rahmen dieser Arbeit rn%, die vollständig auf Monte-Carlo-Simulationen basiert, rnist zum einen ein wesentlicher Beitrag zum grundlegenden Verständnis der Eigenschaft der fehlenden transversalen Energie auf der ersten Triggerstufe geleistet worden.rnZum anderen werden Methoden vorgestellt, mit denen es möglich ist, die etmiss-Triggereffizienz für Standardmodellprozesse und mögliche mSUGRA-Szenarien aus Daten zu bestimmen. rnBei der Optimierung der etmiss-Triggerschwellen für die erste Triggerstufe ist die Triggerrate bei einer Luminosität von 10^33 #/(cm^2*s) auf 100 Hz festgelegt worden.rnFür die Triggeroptimierung wurden verschiedene Simulationen benötigt, bei denen eigene Entwicklungsarbeit eingeflossen ist.rnMit Hilfe dieser Simulationen und den entwickelten Optimierungsalgorithmen wird gezeigt, dass trotz der niedrigen Triggerrate das Entdeckungspotential (für eine Signalsignifikanz von mindestens 5 sigma) durch Kombinationen der etmiss-Schwelle mit Lepton bzw. Jet-Triggerschwellen gegenüber dem bestehenden ATLAS-Triggermenü auf der ersten Triggerstufe um bis zu 66 % erhöht wird.

Hybrid portable systems for bio-nanosensors

The promising development in the routine nanofabrication and the increasing knowledge of the working principles of new classes of highly sensitive, label-free and possibly cost-effective bio-nanosensors for the detection of molecules in liquid environment, has rapidly increased the possibility to develop portable sensor devices that could have a great impact on many application fields, such as health-care, environment and food production, thanks to the intrinsic ability of these biosensors to detect, monitor and study events at the nanoscale. Moreover, there is a growing demand for low-cost, compact readout structures able to perform accurate preliminary tests on biosensors and/or to perform routine tests with respect to experimental conditions avoiding skilled personnel and bulky laboratory instruments. This thesis focuses on analysing, designing and testing novel implementation of bio-nanosensors in layered hybrid systems where microfluidic devices and microelectronic systems are fused in compact printed circuit board (PCB) technology. In particular the manuscript presents hybrid systems in two validating cases using nanopore and nanowire technology, demonstrating new features not covered by state of the art technologies and based on the use of two custom integrated circuits (ICs). As far as the nanopores interface system is concerned, an automatic setup has been developed for the concurrent formation of bilayer lipid membranes combined with a custom parallel readout electronic system creating a complete portable platform for nanopores or ion channels studies. On the other hand, referring to the nanowire readout hybrid interface, two systems enabling to perform parallel, real-time, complex impedance measurements based on lock-in technique, as well as impedance spectroscopy measurements have been developed. This feature enable to experimentally investigate the possibility to enrich informations on the bio-nanosensors concurrently acquiring impedance magnitude and phase thus investigating capacitive contributions of bioanalytical interactions on biosensor surface.

Development and testing of the atlas ibl rod pre production boards

Il lavoro di questa tesi riguarda principalmente la progettazione, simulazione e test di laboratorio di tre versioni successive di schede VME, chiamate Read Out Driver (ROD), che sono state fabbricate per l'upgrade del 2014 dell'esperimento ATLAS Insertable B-Layer (IBL) al CERN. IBL è un nuovo layer che diverrà parte del Pixel Detector di ATLAS. Questa tesi si compone di una panoramica descrittiva dell'esperimento ATLAS in generale per poi concentrarsi sulla descrizione del layer specifico IBL. Inoltre tratta in dettaglio aspetti fisici e tecnici: specifiche di progetto, percorso realizzativo delle schede e test conseguenti. Le schede sono state dapprima prodotte in due prototipi per testare le prestazioni del sistema. Queste sono state fabbricate al fine di valutare le caratteristiche e prestazioni complessive del sistema di readout. Un secondo lotto di produzione, composto di cinque schede, è stato orientato alla correzione fine delle criticità emerse dai test del primo lotto. Un'indagine fine e approfondita del sistema ha messo a punto le schede per la fabbricazione di un terzo lotto di altre cinque schede. Attualmente la produzione è finita e complessivamente sono state realizzate 20 schede definitive che sono in fase di test. La produzione sarà validata prossimamente e le 20 schede verranno consegnate al CERN per essere inserite nel sistema di acquisizione dati del rivelatore. Al momento, il Dipartimento di Fisica ed Astronomia dell'Università di Bologna è coinvolto in un esperimento a pixel solamente attravers IBL descritto in questa tesi. In conclusione, il lavoro di tesi è stato prevalentemente focalizzato sui test delle schede e sul progetto del firmware necessario per la calibrazione e per la presa dati del rivelatore.

The new Beam Halo Monitor for the CMS experiment at the LHC

In the context of increasing beam energy and luminosity of the LHC accelerator at CERN, it will be important to accurately measure the Machine Induced Background. A new monitoring system will be installed in the CMS cavern for measuring the beam background at high radius. This detector, called the Beam Halo Monitor, will provide an online, bunch-by-bunch measurement of background induced by beam halo interactions, separately for each beam. The detector is composed of synthetic quartz Cherenkov radiators, coupled to fast UV sensitive photomultiplier tubes. The directional and fast response of the system allows the discrimination of the background particles from the dominant flux in the cavern induced by pp collision debris, produced within the 25 ns bunch spacing. The readout electronics of this detector will make use of many components developed for the upgrade of the CMS Hadron Calorimeter electronics, with a dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal will be digitized by a charge integrating ASIC, providing both the signal rise time and the charge integrated over one bunch crossing. The backend electronics will record bunch-by-bunch histograms, which will be published to CMS and the LHC using the newly designed CMS beam instrumentation specific DAQ. A calibration and monitoring system has been designed to generate triggered pulses of UV light to monitor the efficiency of the system. The experimental results validating the design of the detector, the calibration system and the electronics will be presented.