A built-in self-test technique for high speed analog-to-digital converters

Fundação para a Ciência e a Tecnologia (FCT) - PhD grant (SFRH/BD/62568/2009)

Standardization of an ELISA test using a recombinant nucleoprotein from the Junin virus as the antigen and serological screening for arenavirus among the population of Nova Xavantina, State of Mato Grosso

INTRODUCTION: Arenavirus hemorrhagic fever is a severe emerging disease. METHODS: Considering that the levels of antibodies against arenavirus in the Brazilian population are completely unknown, we have standardized an ELISA test for detecting IgG antibodies using a recombinant nucleoprotein from the Junin virus as the antigen. This protein was obtained by inserting the gene of the Junin virus nucleoprotein into the genome of Autographa californica nucleopolyhedrovirus, using the Bac-to-Bac baculovirus expression system. This recombinant baculovirus was used to infect S. frugiperda cells (SF9). RESULTS: The infection resulted in synthesis of high concentrations of recombinant protein. This protein was detected on 12.5% polyacrylamide gel and by means of Western blot. Using the standardized ELISA test, 343 samples from the population of Nova Xavantina were analyzed. We observed that 1.4% of the serum samples (five samples) presented antibody titers against arenavirus. CONCLUSIONS: These results show the population studied may present exposure to arenavirus infection.

Evaluation of the six-minute walk test in patients with chronic heart failure associated with Chagas' disease and systemic arterial hypertension

INTRODUCTION: To evaluate physical capacity as determined by the six-minute walk test (6MWT) in patients with chronic heart failure due to Chagas' disease associated with systemic arterial hypertension (Chagas-SAH). METHODS: A total of 98 patients routinely followed at the Cardiomyopathy Outpatient Service were recruited. Of these, 60 (61%) were diagnosed with Chagas disease and 38 (39%) with Chagas-SAH. RESULTS: The distance walked during 6 min was 357.9 ±98 m for Chagas-SAH patients and 395.8 ± 121m for Chagas cardiomyopathy patients (p >0.05). In patients with Chagas-SAH, a negative correlation occurred between the 6MWT and the total score of the Minnesota Living with Heart Failure Questionnaire (r= -0.51; p=0.001). No other correlations were determined between 6MWT values and continuous variables in patients with Chagas-SAH. CONCLUSIONS: The results of the 6MWT in Chagas-SAH patients are similar to those verified in Chagas cardiomyopathy patients with chronic heart failure. Coexistence of SAH does not seem to affect the functional capacity of Chagas cardiomyopathy patients with chronic heart failure.

Creation of a web application for smart park system and parking prediction study for system integration

In the last few years, we have observed an exponential increasing of the information systems, and parking information is one more example of them. The needs of obtaining reliable and updated information of parking slots availability are very important in the goal of traffic reduction. Also parking slot prediction is a new topic that has already started to be applied. San Francisco in America and Santander in Spain are examples of such projects carried out to obtain this kind of information. The aim of this thesis is the study and evaluation of methodologies for parking slot prediction and the integration in a web application, where all kind of users will be able to know the current parking status and also future status according to parking model predictions. The source of the data is ancillary in this work but it needs to be understood anyway to understand the parking behaviour. Actually, there are many modelling techniques used for this purpose such as time series analysis, decision trees, neural networks and clustering. In this work, the author explains the best techniques at this work, analyzes the result and points out the advantages and disadvantages of each one. The model will learn the periodic and seasonal patterns of the parking status behaviour, and with this knowledge it can predict future status values given a date. The data used comes from the Smart Park Ontinyent and it is about parking occupancy status together with timestamps and it is stored in a database. After data acquisition, data analysis and pre-processing was needed for model implementations. The first test done was with the boosting ensemble classifier, employed over a set of decision trees, created with C5.0 algorithm from a set of training samples, to assign a prediction value to each object. In addition to the predictions, this work has got measurements error that indicates the reliability of the outcome predictions being correct. The second test was done using the function fitting seasonal exponential smoothing tbats model. Finally as the last test, it has been tried a model that is actually a combination of the previous two models, just to see the result of this combination. The results were quite good for all of them, having error averages of 6.2, 6.6 and 5.4 in vacancies predictions for the three models respectively. This means from a parking of 47 places a 10% average error in parking slot predictions. This result could be even better with longer data available. In order to make this kind of information visible and reachable from everyone having a device with internet connection, a web application was made for this purpose. Beside the data displaying, this application also offers different functions to improve the task of searching for parking. The new functions, apart from parking prediction, were: - Park distances from user location. It provides all the distances to user current location to the different parks in the city. - Geocoding. The service for matching a literal description or an address to a concrete location. - Geolocation. The service for positioning the user. - Parking list panel. This is not a service neither a function, is just a better visualization and better handling of the information.

Improvement of a PCR test to diagnose infection by Mansonella ozzardi

INTRODUCTION: Mansonelliasis is caused by Mansonella ozzardi. It is widespread in the Amazon region, with a high prevalence. The common exam of thick blood smears stained with Giemsa shows low efficacy levels and has been an obstacle to diagnosing individuals with low blood parasitemia. METHODS: In order to increase diagnosis efficacy, the PCR technique was improved. RESULTS AND CONCLUSIONS: PCR demonstrated the best performance, with sensitivity and negative predictive values (NPV) of 100%, followed by blood filtration through membrane filters, which showed a sensitivity of 88.9% and a NPV of 84.6%, when compared to thick blood smears.

Digital microfluidics on paper

This thesis is one of the first reports of digital microfluidics on paper and the first in which the chip’s circuit was screen printed unto the paper. The use of the screen printing technique, being a low cost and fast method for electrodes deposition, makes the all chip processing much more aligned with the low cost choice of paper as a substrate. Functioning chips were developed that were capable of working at as low as 50 V, performing all the digital microfluidics operations: movement, dispensing, merging and splitting of the droplets. Silver ink electrodes were screen printed unto paper substrates, covered by Parylene-C (through vapor deposition) as dielectric and Teflon AF 1600 (through spin coating) as hydrophobic layer. The morphology of different paper substrates, silver inks (with different annealing conditions) and Parylene deposition conditions were studied by optical microscopy, AFM, SEM and 3D profilometry. Resolution tests for the printing process and electrical characterization of the silver electrodes were also made. As a showcase of the applications potential of these chips as a biosensing device, a colorimetric peroxidase detection test was successfully done on chip, using 200 nL to 350 nL droplets dispensed from 1 μL drops.

Interpretation of the presence of IgM and IgG antibodies in a rapid test for dengue: analysis of dengue antibody prevalence in Fortaleza City in the 20th year of the epidemic

INTRODUCTION: The diagnosis of dengue and the differentiation between primary and secondary infections are important for monitoring the spread of the epidemic and identifying the risk of severe forms of the disease. The detection of immunoglobulin (Ig)M and IgG antibodies is the main technique for the laboratory diagnosis of dengue. The present study assessed the application of a rapid test for dengue concerning detection of new cases, reinfection recognition, and estimation of the epidemic attack rate. METHODS: This was a retrospective, cross-sectional, descriptive study on dengue using the Fortaleza Health Municipal Department database. The results from 1,530 tested samples, from 2005-2006, were compared with data from epidemiological studies of dengue outbreaks in 1996, 2003, and 2010. RESULTS: The rapid test confirmed 52% recent infections in the tested patients with clinical suspicion of dengue: 40% detected using IgM and 12% of new cases using IgG in the non-reactive IgM results. The positive IgM plus negative IgG (IgM+ plus IgG-) results showed that 38% of those patients had a recent primary dengue infection, while the positive IgG plus either positive or negative IgM (IgG+ plus IgM+/-) results indicated that 62% had dengue for at least a second time (recent secondary infections). This proportion of reinfections permitted us to estimate the attack rate as >62% of the population sample. CONCLUSIONS: The rapid test for dengue has enhanced our ability to detect new infections and to characterize them into primary and secondary infections, permitting the estimation of the minimal attack rate for a population during an outbreak.

Insurance segmentation as unfair discrimination: what to expect next in the wake of Test-Achats

Proceedings of the 16th Annual Conference organized by the Insurance Law Association of Serbia and German Foundation for International Legal Co-Operation (IRZ), entitled "Insurance law, governance and transparency: basics of the legal certainty" Palic Serbia, 17-19 April 2015.

Evaluation of the diagnostic value of the tourniquet test in predicting severe dengue cases in a population from Belo Horizonte, State of Minas Gerais, Brazil

Introduction Dengue is prevalent in many tropical and sub-tropical regions. The clinical diagnosis of dengue is still complex, and not much data are available. This work aimed at assessing the diagnostic accuracy of the tourniquet test in patients with suspected dengue infection and its positivity in different classifications of this disease as reported to the Information System for Notifiable Disease in Belo Horizonte, State of Minas Gerais, Brazil between 2001 and 2006. Methods Cross-section analysis of the diagnostic accuracy of the tourniquet test for dengue, using IgM-anti-DENV ELISA as a gold standard. Results We selected 9,836 suspected cases, of which 41.1% were confirmed to be dengue. Classic dengue was present in 95.8%, dengue with complications in 2.5% and dengue hemorrhagic fever in 1.7%. The tourniquet test was positive in 16.9% of classic dengue cases, 61.7% of dengue cases with complications and 82.9% of cases of dengue hemorrhagic fever. The sensitivity and specificity of the tourniquet test were 19.1% and 86.4%, respectively. Conclusions A positive tourniquet test can be a valuable tool to support diagnosis of dengue where laboratory tests are not available. However, the absence of a positive test should not be read as the absence of infection. In addition, the tourniquet test was demonstrated to be an indicator of dengue severity.

Effects of quantitative easing on the USA economy: A test for policy effectiveness

The catastrophic disruption in the USA financial system in the wake of the financial crisis prompted the Federal Reserve to launch a Quantitative Easing (QE) programme in late 2008. In line with Pesaran and Smith (2014), I use a policy effectiveness test to assess whether this massive asset purchase programme was effective in stimulating the economic activity in the USA. Specifically, I employ an Autoregressive Distributed Lag Model (ARDL), in order to obtain a counterfactual for the USA real GDP growth rate. Using data from 1983Q1 to 2009Q4, the results show that the beneficial effects of QE appear to be weak and rather short-lived. The null hypothesis of policy ineffectiveness is not rejected, which suggests that QE did not have a meaningful impact on output growth.

Performance of a rapid diagnostic test for the detection of visceral leishmaniasis in a large urban setting

Introduction Rapid diagnostic tests (RDTs) may improve the early detection of visceral leishmaniasis (VL), but their real-world performance requires additional study. Therefore, we evaluated the performance of an rK39-based RDT (Kalazar Detect™) for the detection of VL in an endemic, large urban area. Methods Data were collected from a registry of rK39 RDT performed at 11 emergency care units in Belo Horizonte, Brazil, and from a national database of reportable communicable diseases of the Sistema de Informação de Agravos de Notificação (SINAN). Results The rapid rK39 test was performed in 476 patients, with 114 (23.9%) positive results. The analysis of rK39 RDT performance was based on 381 (80%) cases reported to the SINAN database, of which 145 (38.1%) were confirmed cases. Estimates for sensitivity and specificity were 72.4% (95% CI: 64.6-79%) and 99.6% (95%CI: 97.6-99.9%), respectively. Positive and negative predictive values were estimated at 99.1% (95%CI: 94.9-99.8%) and 85.5% (95%CI: 80.8-89.1%), respectively. In addition, close agreement between the rK39 RDT and indirect immunofluorescence was observed. Conclusions In summary, the rK39 RDT showed a high specificity but only moderate sensitivity. In endemic areas for VL, treatment may be considered in cases with clinical manifestations and a positive rK39 RDT, but those with a negative test should be subjected to further investigation.

Using an LED as a sensor and visible light communication device in a smart illumination system

The need for more efficient illumination systems has led to the proliferation of Solid-State Lighting (SSL) systems, which offer optimized power consumption. SSL systems are comprised of LED devices which are intrinsically fast devices and permit very fast light modulation. This, along with the congestion of the radio frequency spectrum has paved the path for the emergence of Visible Light Communication (VLC) systems. VLC uses free space to convey information by using light modulation. Notwithstanding, as VLC systems proliferate and cost competitiveness ensues, there are two important aspects to be considered. State-of-the-art VLC implementations use power demanding PAs, and thus it is important to investigate if regular, existent Switched-Mode Power Supply (SMPS) circuits can be adapted for VLC use. A 28 W buck regulator was implemented using a off-the-shelf LED Driver integrated circuit, using both series and parallel dimming techniques. Results show that optical clock frequencies up to 500 kHz are achievable without any major modification besides adequate component sizing. The use of an LED as a sensor was investigated, in a short-range, low-data-rate perspective. Results show successful communication in an LED-to-LED configuration, with enhanced range when using LED strings as sensors. Besides, LEDs present spectral selective sensitivity, which makes them good contenders for a multi-colour LED-to-LED system, such as in the use of RGB displays and lamps. Ultimately, the present work shows evidence that LEDs can be used as a dual-purpose device, enabling not only illumination, but also bi-directional data communication.

Performance of the Vitek 2 system software version 5.03 in the bacterial identification and antimicrobial susceptibility test: evaluation study of clinical and reference strains of Gram-positive cocci

Introduction. The genera Enterococcus, Staphylococcus and Streptococcus are recognized as important Gram-positive human pathogens. The aim of this study was to evaluate the performance of Vitek 2 in identifying Gram-positive cocci and their antimicrobial susceptibilities. Methods. One hundred four isolates were analyzed to determine the accuracy of the automated system for identifying the bacteria and their susceptibility to oxacillin and vancomycin. Results. The system correctly identified 77.9% and 97.1% of the isolates at the species and genus levels, respectively. Additionally, 81.8% of the Vitek 2 results agreed with the known antimicrobial susceptibility profiles. Conclusion. Vitek 2 correctly identified the commonly isolated strains; however, the limitations of the method may lead to ambiguous findings.

Evaluation of three enzyme immunoassays and a nucleic acid amplification test for the diagnosis of Clostridium difficile-associated diarrhea at a university hospital in Brazil

Introduction Despite the known importance of Clostridium difficile as a nosocomial pathogen, few studies regarding Clostridium difficile infection (CDI) in Brazil have been conducted. To date, the diagnostic tests that are available on the Brazilian market for the diagnosis of CDI have not been evaluated. The aim of this study was to compare the performances of four commercial methods for the diagnosis of CDI in patients from a university hospital in Brazil. Methods Three enzyme immunoassays (EIAs) and one nucleic acid amplification test (NAAT) were evaluated against a cytotoxicity assay (CTA) and toxigenic culture (TC). Stool samples from 92 patients with suspected CDI were used in this study. Results Twenty-five (27.2%) of 92 samples were positive according to the CTA, and 23 (25%) were positive according to the TC. All EIAs and the NAAT test demonstrated sensitivities between 59 and 68% and specificities greater than 91%. Conclusions All four methods exhibited low sensitivities for the diagnosis of CDI, which could lead to a large number of false-negative results, an increased risk of cross-infection to other patients, and overtreatment with empirical antibiotics.

Construct and diagnostic validities of the Free and Cued Selective Reminding Test in the alzheimer’s disease spectrum

The Free and Cued Selective Reminding Test (FCSRT) is a memory test that controls attention and acquisition, by providing category cues in the learning process. Because it enables an assessment of memory not confounded by normal age-related changes in cognition and a high accuracy on Alzheimer's disease (AD) evaluation, it has been suggested by the International Working Group on AD. Our aim was to assess the construct related validity of the FCSRT in the AD spectrum disorders.