Detection and Diagnosis of Bacterial Pathogens in Blood Using Laser-Induced Breakdown Spectroscopy

The ability to rapidly and accurately detect and identify pathogenic bacteria in clinically-obtained blood specimens with laser-induced breakdown spectroscopy (LIBS) is evaluated. Samples of blood obtained from five patients in a local hospital were confirmed to be negative for the presence of bacteria by the pathology department and were then tested with LIBS. Specimens of blood were tested as obtained from the hospital with no other alteration as control samples and were also intentionally spiked with known aliquots of Escherichia coli, Staphylococcus aureus, Enterobacter cloacae, and Pseudomonas aeruginosa to simulate blood infections. LIBS spectra were acquired from blood deposited on nitrocellulose filters. The intensities of 15 emission lines measured in the spectra and 92 ratios of those line intensities were used as 107 independent variables in a partial least squares discriminant analysis (PLS-DA) to discriminate between sterile control samples and those spiked with bacteria. In addition, the entire LIBS spectrum from 200 nm – 590 nm was input into an artificial neural network analysis with principal component analysis pre-processing (PCA-ANN) to diagnose the bacterial species once detected. The PLS-DA test possessed a 96.3% sensitivity and a 98.6% specificity for the detection of pathogenic bacteria in blood when 776 spectra from 26 filters were tested by removing one entire filter at a time from the model and testing each spectrum individually. When all the spectra obtained from a filter were averaged to enhance the signal to noise of the spectrum, 19 of 19 filters of infected blood tested positive and 7 of 7 filters with sterile blood tested negative, yielding 100% sensitivity and 100% specificity. The PCA-ANN test performed on the entire LIBS spectrum possessed a 100% sensitivity and 100% specificity when using 80% of the data to build a model and withholding 20% for cross-validation testing. The same PCA-ANN performed on each of the 19 filters individually, using the other 18 filters to build the model, possessed an average sensitivity of 85.5%, an average specificity of 95.0%, and a classification accuracy of 92.5%. These results indicate the potential usefulness of LIBS for detecting and diagnosing blood infections in a clinical setting

Detection and Diagnosis of Bacterial Pathogens in Urine Using Laser-Induced Breakdown Spectroscopy

The presence of bacterial cells from three species has been detected in clinical specimens of human urine using laser-induced breakdown spectroscopy (LIBS) by using a partial least squares discriminant analysis (PLS-DA) of 360 spectra obtained from 12 specimens of infected urine and 239 spectra obtained from eight specimens of sterile urine. Nominally sterile urine specimens obtained from four patients at a local hospital after being screened negative for the presence of bacterial pathogens were spiked with known aliquots of Escherichia coli, Staphylococcus aureus, and Enterobacter cloacae to simulate clinical urinary tract infections. Fifteen emission line intensities measured from the LIBS spectra and 92 ratios of those line intensities were used as 107 independent variables in the PLS-DA for discrimination between bacteria-containing specimens and sterile specimens. The PLS-DA models possessed a 98.3% sensitivity and a 97.9% specificity for the detection of pathogenic cells in urine when single-shot LIBS spectra were tested. To increase the signal to noise ratio, thirty spectra acquired from a single specimen were also averaged together and the averaged spectra were used to construct a model. When each averaged spectrum was withheld from the model individually for testing, the diagnostic test possessed a 100% sensitivity and a 100% specificity for the detection of bacterial cells in urine, although the number of test spectra was necessarily reduced. The entire LIBS spectrum from 200 nm – 590 nm was input into an artificial neural network analysis with principal component analysis pre-processing (PCA-ANN) to diagnose the bacterial species once detected. This PCA-ANN test possessed an overall sensitivity of 97.2%, an overall specificity of 98.6%, and an overall classification accuracy of 97.9% when using 80% of the data to build a model and withholding 20% for crossvalidation testing. The PCA-ANN was also performed on each of the 12 bacteria-containing filters individually, using the other 11 filters to build the model. The average sensitivity of this test, calculated by averaging the sensitivities measured for each of the three bacterial species, was 70.9% and the average specificity was 85.5%. Based on these results, the average classification accuracy for the test when used to discriminate between the three microorganisms was 80.6%. These results indicate the potential usefulness of LIBS for rapidly detecting and possibly diagnosing urinary tract infections in a clinical setting

Students understanding of integral calculus

Det här arbetet har haft som syfte att ta reda på vilka uppfattningar eleverna på en Komvuxskola har om integralkalkyl. I undersökningen medverkade 28 elever och fyra av dem blev intervjuade. Jag använde mig av ett skriftligt test och kvalitativa ostrukturerade intervjuer som undersökningsmetoder. Studiens resultat visade att endast några elever tolkade begreppen primitiv funktion samt integral som ett objekt och utvecklade relationell förståelse. De andra eleverna som på det skriftliga testet kunde tillämpa reglerna för att bestämma primitiva funktioner och för att beräkna integraler, uppfattade begreppen som en process och utvecklade instrumentell förståelse. De felaktiga svaren grundade sig på svårigheter med: algebraiska manipulationer, grundläggande algebra och hantering av grafräknaren. När det gäller elevernas förståelse om sambandet mellan funktionens och primitiva funktionens graf visade eleverna svårigheter med övergången från den grafiska till den symboliska representationsformen. De eleverna som använde sig av grafräknaren på ett effektivt sätt fick bättre resultat än de andra som skrev att grafräknaren inte kom till någon användning

Samhällets kameleonter : En kvalitativ studie om andra generationens invandrares tredje identitet och mellanförskap

The overall aim of the study is to create a greater understanding of how individuals belonging to second-generation immigrants feel that their identity is shaped by living in different cultures at the same time. The purpose includes to understand these individuals' experiences of belonging and sense of identity. Furthermore, the purpose is to create a greater understanding of how their experiences can be seen in relation to social segregation and discrimination. The method for this study was semi-structured qualitative interviews with six second generation immigrants born in Malmö, with two parents born in another country than Sweden. The selection of individuals for this study has also been limited to individuals being raised in Malmö’s multicultural and segregated areas. The empirical material collected from the interviews has been analyzed with the support of theories about cultural identity, hybridity, identity construction and has also been analyzed with support from previous research. The results of this study showed that second-generation immigrants feel “in between” of cultures and they have a difficulty describing their identity. All informants stated that they constantly have to adapt to different cultures in their everyday life. However, there were times when the respondents did not have to adapt. These occasions were when they interacted with other individuals who are also second generation immigrants. They felt that they had somehow created their own culture, a common culture where they understand each other in a way that no one else does. Respondents considered that racism and discrimination in society weakened their sense of belonging and felt stigmatized in society. The fact that the respondents did not feel understood by either the community or the family contributed to the weakened sense of belonging. In this space, “in between cultures”, they have created their own culture, a culture that is not accepted or understood by the society

Improving Stroke Disability Through Neural Reorganization

Neuroscience has made strides in recent years allowing insight into the molecular and regional anatomy and function of the brain. This has given researchers an advantage in seeking novel therapies for neurological disorders, specifically stroke. This review outlines the current understanding of neurological repair after stroke and the neuroimaging techniques that enable further study. Neuronal connectivity has varying levels of complexity that allow neuronal networks to process information and give rise to our daily functioning. As stroke causes the death of groups of regional neurons, it is likely that the reestablishment of function seen in some stroke patients is related to shifting patterns of functional connectivity. This paper elucidates the timeline and limits on the amount of functional recovery, as well as the differences in organization of neuronal networks in a healthy versus post stroke brain. A long-lasting period of enhanced neuroplasticity post-stroke has been found that enables functional improvement even at late chronic stages. Finally, we discuss how the previous methods of imaging are critical in understanding the mechanisms of functional recovery. The best understood mechanism of neural repair is axonal sprouting, a process where new nerve fibres sprout from intact axons to reinnervate target cells. The three distinct types are discussed, along with potential ways of imaging them in rodents. The hope is that, with a better understanding of the mechanisms underlying brain recovery, researchers can apply this in clinical settings to better help stroke patients recover from this debilitating disease and greatly improve quality of life and autonomy

Modelling and simulation of a wind energy system

Nowadays, wind energy systems are the most efficient systems of all renewable energy production systems. Therefore, all sizes and types of this kind of systems are available, but there are few portable systems which can be temporarily mounted in certain isolated areas. We propose in this case study another solution as an alternative: an adaptable mechatronic system which can withstand even in very difficult and challenging weather conditions due to their active surfaces that have reconfigurable automatic structure

Noise assessment of the small-scale wind farm

The importance of renewable energy and especially of eolian systems is growing. For this reason, we propose the investigation of an important pollutant - the noise, which has become so important that European Commission and European Parliament introduced Directive 2002/49/CE relating to the assessment and management of environmental noise. So far, priority has been given to very large-scale systems connected to national energy systems, wind farms whose highly variable output power could be regulated by large power systems. Nowadays, with the development of small storage capacities, it is feasible to install small power wind turbines in cities of up to 10,000 inhabitants too. As a case study, we propose a simulation for a rural locality where individual wind units could be used. This specific case study is interesting because it provides a new perspective of the impact of noise on the quality of life when the use of this type of system is implemented on a large scale. This option, of distributed and small power wind turbine, can be implemented in the future as an alternative or an adding to the common systems

Researches on the development of an optical system for improving the efficiency of photovoltaic panels

The paper aims to create a unit using Fresnel lenses. This module consist of an arrangement of planar-convex Fresnel lenses, made of methyl polymethacrylate, mounted in a hexagonal raster and bent to form a dome for collecting and amplifying solar radiation at several focal points and with the possibility of adjusting the focal distance. The module has three aluminum alloy legs that are vertically adjustable. This construction using Fresnel lenses mounted in a hexagonal raster will increase the energy collected by a photovoltaic panel, thus significantly reducing energy losses and long-term costs. Compared to normal lenses, these lenses are considerably lighter because the material in the center of the lens is reduced, and for manufacturing can be used methyl polymethacrylate or polycarbonate, thus greatly reducing manufacturing costs. To show the functioning of the unit the authors presents in the paper a MATLAB simulation of the Fresnel lens model and a ray propagation