Minimizing Circulating Current in Parallel-Connected Photovoltaic Inverters

Parallel-connected photovoltaic inverters are required in large solar plants where it is not economically or technically reasonable to use a single inverter. Currently, parallel inverters require individual isolating transformers to cut the path for the circulating current. In this doctoral dissertation, the problem is approached by attempting to minimize the generated circulating current. The circulating current is a function of the generated common-mode voltages of the parallel inverters and can be minimized by synchronizing the inverters. The synchronization has previously been achieved by a communication link. However, in photovoltaic systems the inverters may be located far apart from each other. Thus, a control free of communication is desired. It is shown in this doctoral dissertation that the circulating current can also be obtained by a common-mode voltage measurement. A control method based on a short-time switching frequency transition is developed and tested with an actual photovoltaic environment of two parallel inverters connected to two 5 kW solar arrays. Controls based on the measurement of the circulating current and the common-mode voltage are generated and tested. A communication-free method of controlling the circulating current between parallelconnected inverters is developed and verified.

Tuoteportfolion hallinnointiprosessin erityispiirteet lääketeollisuusyrityksessä – tapaustutkimus

Tämän pro gradu -tutkielman tarkoituksena oli selvittää, miten lääketeollisuusyritys toteuttaa tuoteportfolioidensa hallinnointia ja miten tämän caseyrityksen portfolioprosessi vastaa kirjallisuuden näkemystä tuoteportfolion hallinnoinnista. Tutkimusongelmaa lähestyttiin tapaustutkimuksella caseyrityksen portfolioprosessista, ja tätä prosessia verrattiin kirjallisuuden näkemykseen aiheesta. Empiiristä aineistoa kerättiin pääosin teema- ja lomakehaastatteluilla caseyrityksen projektin avainhenkilöiltä. Tutkimuksessa havaittiin portfolioprosessin olevan vaiheittainen toimintamalli, jonka tavoitteena on hankkia mahdollisimman kannattava tuotevalikoima. Caseyrityksen portfolioprosessi vastasi pääosin aiheen teorian kuvaamaa mallia, mutta prosessia ja etenkin karsintakriteereitä monipuolistamalla voidaan tulevaisuudessa saavuttaa parempia tuloksia. Lääketeollisuudella toimialana on tiettyjä ominaispiirteitä, mutta nämä eivät suoraan näy varsinaisessa portfolioprosessissa. Kuitenkin esimerkiksi erityyppisten liiketoimintayksiköiden tarpeet olisi syytä huomioida tuoteportfolion hallinnointiprosessissa.

Rapid, reliable and inexpensive quality assessment of biotinylated cRNA

The interpretation of oligonucleotide array experiments depends on the quality of the target cRNA used. cRNA target quality is assessed by quantitative analysis of the representation of 5' and 3' sequences of control genes using commercially available Test arrays. The Test array provides an economically priced means of determining the quality of labeled target prior to analysis on whole genome expression arrays. This manuscript validates the use of a duplex RT-PCR assay as a faster (6 h) and less expensive (arrays in determining biotinylated cRNA quality. Forty-one different cRNA samples were hybridized to HG-U133A microarrays from Affymetrix. Ten cRNA samples with a ß-actin 3'/5' ratio >6 were chosen and classified as degraded cRNAs, and 31 samples with a ß-actin 3'/5' ratio <6 were selected as good quality cRNAs. Blinded samples were then used for the RT-PCR assay. After gel electrophoresis, optical densities of the amplified 3' and 5' fragments of ß-actin were measured and the 3'/5' ratio was calculated. There was a strong correlation (r² = 0.6802) between the array and the RT-PCR ß-actin 3'/5' ratios. Moreover, the RT-PCR 3'/5' ratio was significantly different (P < 0.0001) between undegraded (mean ± SD, 0.34 ± 0.09) and degraded (1.71 ± 0.83) samples. None of the other parameters analyzed, such as i) the starting amount of RNA, ii) RNA quality assessed using the Bioanalyzer Chip technology, or iii) the concentration and OD260/OD280 ratio of the purified biotinylated cRNA, correlated with cRNA quality.

Intrinsic bent DNA sites in the chromosomal replication origin of Xylella fastidiosa 9a5c

The features of the nucleotide sequences in both replication and promoter regions have been investigated in many organisms. Intrinsically bent DNA sites associated with transcription have been described in several prokaryotic organisms. The aim of the present study was to investigate intrinsic bent DNA sites in the segment that holds the chromosomal replication origin, oriC, of Xylella fastidiosa 9a5c. Electrophoretic behavior analyses, as well as in silico analyses of both the 2-D projection and helical parameters, were performed. The chromosomal segment analyzed contains the initial sequence of the rpmH gene, an intergenic region, the dnaA gene, the oriC sequence, and the 5' partial sequence of the dnaN gene. The analysis revealed fragments with reduced electrophoretic mobility, which indicates the presence of curved DNA segments. The analysis of the helical parameter ENDS ratio revealed three bent DNA sites (b1, b2, and b3) located in the rpmH-dnaA intergenic region, the dnaA gene, and the oriC 5' end, respectively. The chromosomal segment of X. fastidiosa analyzed here is rich in phased AT tracts and in CAnT motifs. The 2-D projection indicated a segment whose structure was determined by the cumulative effect of all bent DNA sites. Further, the in silico analysis of the three different bacterial oriC sequences indicated similar negative roll and twist >34.00° values. The DnaA box sequences, and other motifs in them, may be associated with the intrinsic DNA curvature.

Performance assessment of the single photon emission microscope: high spatial resolution SPECT imaging of small animal organs

The single photon emission microscope (SPEM) is an instrument developed to obtain high spatial resolution single photon emission computed tomography (SPECT) images of small structures inside the mouse brain. SPEM consists of two independent imaging devices, which combine a multipinhole collimator, a high-resolution, thallium-doped cesium iodide [CsI(Tl)] columnar scintillator, a demagnifying/intensifier tube, and an electron-multiplying charge-coupling device (CCD). Collimators have 300- and 450-µm diameter pinholes on tungsten slabs, in hexagonal arrays of 19 and 7 holes. Projection data are acquired in a photon-counting strategy, where CCD frames are stored at 50 frames per second, with a radius of rotation of 35 mm and magnification factor of one. The image reconstruction software tool is based on the maximum likelihood algorithm. Our aim was to evaluate the spatial resolution and sensitivity attainable with the seven-pinhole imaging device, together with the linearity for quantification on the tomographic images, and to test the instrument in obtaining tomographic images of different mouse organs. A spatial resolution better than 500 µm and a sensitivity of 21.6 counts·s-1·MBq-1 were reached, as well as a correlation coefficient between activity and intensity better than 0.99, when imaging 99mTc sources. Images of the thyroid, heart, lungs, and bones of mice were registered using 99mTc-labeled radiopharmaceuticals in times appropriate for routine preclinical experimentation of <1 h per projection data set. Detailed experimental protocols and images of the aforementioned organs are shown. We plan to extend the instrument's field of view to fix larger animals and to combine data from both detectors to reduce the acquisition time or applied activity.

Whole transcriptome organisation in the dehydrated supraoptic nucleus

The supraoptic nucleus (SON) is part of the central osmotic circuitry that synthesises the hormone vasopressin (Avp) and transports it to terminals in the posterior lobe of the pituitary. Following osmotic stress such as dehydration, this tissue undergoes morphological, electrical and transcriptional changes to facilitate the appropriate regulation and release of Avp into the circulation where it conserves water at the level of the kidney. Here, the organisation of the whole transcriptome following dehydration is modelled to fit Zipf's law, a natural power law that holds true for all natural languages, that states if the frequency of word usage is plotted against its rank, then the log linear regression of this is -1. We have applied this model to our previously published euhydrated and dehydrated SON data to observe this trend and how it changes following dehydration. In accordance with other studies, our whole transcriptome data fit well with this model in the euhydrated SON microarrays, but interestingly, fit better in the dehydrated arrays. This trend was observed in a subset of differentially regulated genes and also following network reconstruction using a third-party database that mines public data. We make use of language as a metaphor that helps us philosophise about the role of the whole transcriptome in providing a suitable environment for the delivery of Avp following a survival threat like dehydration.

Nursing students and older people nursing. Towards a future career

The purpose of this two-phased study is to examine the interest of nursing students in choosing a career in older people nursing. First, the scoping phase explores the different premises for choosing older people nursing as a career. Second, the evaluation phase investigates the outcomes of the developed educational intervention involving older people as promoters of choosing a career in older people nursing, factors related to these outcomes, and experiences with educational intervention. The ultimate goal is to encourage more nursing students to choose older people nursing as their career. The scoping phase applies an exploratory design and centres around a descriptive, cross-sectional survey, documentary research and a scoping literature review. The information sources for this phase include 183 nursing students, 101 newspaper articles and 66 research articles. The evaluation phase applies a quasi-experimental design and a pre-post-test design with a non-equivalent comparison group and a post-intervention survey. The information sources for this phase include 87 nursing students and 43 older people. In both phases, statistical and narrative methods are applied in the data analysis. Nursing students neutrally regarded the idea of a career in older people nursing. The most consistent factors related to the nursing students’ career plans in older people nursing were found to be nursing work experience and various educational preparations in the field. Nursing students in the intervention group (n=40) were more interested in older people nursing and had more positive attitudes towards older people than did students in the comparison group (n=36). However, in both groups, the interest that students had at the baseline was associated with the interest at the one-month follow-up. There were no significant differences between the groups in terms of the students’ knowledge levels about ageing. The nursing students and older people alike highly appreciated participating in the educational intervention. It seems possible to positively impact nursing students and their choices to pursue careers in older people nursing, at least in the short-term. The involvement of older people as promoters of this career choice provides one encouraging alternative for impacting students’ career choices, but additional research is needed.

Pollen and grain size records in abyssal sediments of the northwest Pacific Ocean as proxies of Plio-Pleistocene climate change /

A distinctive period of global change occurred during the PUocene between the warm Miocene and subsequent Quaternary cooling. Samples from Ocean Drilling Project Site 11 79 (-5586 mbsl, 41°4'N, 159°57'E), Site 881 (-5765 mbsl, 47°6.133'N, 161°29.490'E) and Site 882 (-3255 mbsl, 50°22'N, 167°36'E) were studied to determine the magnitude and composition ofterrigenous flux to the western mid-latitude North Pacific and its relation to climate change in East Asia since the mid-Pliocene. Dust-sized particles (including pollen), sourced from the arid regions and loess plateaus in East Asia are entrained by prevailing westerly winds and transported to the midlatitude northwest North Pacific Ocean. This is recorded by peaks in the total concentration of pollen and spores, as well as the mean grain size of allochthonous and autochthonous silicate material in abyssal marine sediments. Aridification of the Asian interior due to the phased uplift of the Himalayan-Tibetan Plateau created the modem East Asian Monsoon system dominated by a strengthening of the winter monsoon. The winter monsoon is further enhanced during glacials due to the expansion of desert and steppe environments at the expense ofwoodlands and forests recorded by the composition of palynological assemblages. The late Pliocene-Pleistocene glacials at ODP Sites 1 179, 881, and 882 are characterized by increases in grain size, magnetic susceptibility, pollen and spore concentrations around 3.5-3.3, 2.6-2.4, 1.7-1.6, and 0.9-0.7 Ma (ages based on magnetostratigraphic and biostratigraphic datums). The peaks during these times are relatively rich in pollen taxa derived primarily from steppe and boreal vegetation zones, recording cool, dry climates. The overall size increase of sediment and abundance of terrestrial palynomorphs record enhanced wind strength. The increase in magnitude of pollen and spore concentrations as well as grain size record global cooling and Northern Hemisphere glaciation. The peaks in grain size as well as pollen and spore abundance in marine sediments correlate with the mean grain size of loess in East Asia, consistent with the deflation of unarmoured surfaces during glacials. The transport of limiting nutrients to marine environments enhanced sea surface productivity and increased the rate of sediment accumulation.

An Investigation of the Role of Attention in the Cross-Race Effect: An Ecological Approach

The current set of studies was conducted to examine the cross-race effect (CRE), a phenomenon commonly found in the face perception literature. The CRE is evident when participants display better own-race face recognition accuracy than other-race recognition accuracy (e.g. Ackerman et al., 2006). Typically the cross-race effect is attributed to perceptual expertise, (i.e., other-race faces are processed less holistically; Michel, Rossion, Han, Chung & Caldara, 2006), and the social cognitive model (i.e., other-race faces are processed at the categorical level by virtue of being an out-group member; Hugenberg, Young, Bernstein, & Sacco, 2010). These effects may be mediated by differential attention. I investigated whether other-race faces are disregarded and, consequently, not remembered as accurately as own-race (in-group) faces. In Experiment 1, I examined how the magnitude of the CRE differed when participants learned individual faces sequentially versus when they learned multiple faces simultaneously in arrays comprising faces and objects. I also examined how the CRE differed when participants recognized individual faces presented sequentially versus in arrays of eight faces. Participants’ recognition accuracy was better for own-race faces than other-race faces regardless of familiarization method. However, the difference between own- and other-race accuracy was larger when faces were familiarized sequentially in comparison to familiarization with arrays. Participants’ response patterns during testing differed depending on the combination of familiarization and testing method. Participants had more false alarms for other-race faces than own-race faces if they learned faces sequentially (regardless of testing strategy); if participants learned faces in arrays, they had more false alarms for other-race faces than own-races faces if ii i they were tested with sequentially presented faces. These results are consistent with the perceptual expertise model in that participants were better able to use the full two seconds in the sequential task for own-race faces, but not for other-race faces. The purpose of Experiment 2 was to examine participants’ attentional allocation in complex scenes. Participants were shown scenes comprising people in real places, but the head stimuli used in Experiment 1 were superimposed onto the bodies in each scene. Using a Tobii eyetracker, participants’ looking time for both own- and other-race faces was evaluated to determine whether participants looked longer at own-race faces and whether individual differences in looking time correlated with individual differences in recognition accuracy. The results of this experiment demonstrated that although own-race faces were preferentially attended to in comparison to other-race faces, individual differences in looking time biases towards own-race faces did not correlate with individual differences in own-race recognition advantages. These results are also consistent with perceptual expertise, as it seems that the role of attentional biases towards own-race faces is independent of the cognitive processing that occurs for own-race faces. All together, these results have implications for face perception tasks that are performed in the lab, how accurate people may be when remembering faces in the real world, and the accuracy and patterns of errors in eyewitness testimony.

Bank of Canada Records, 1958-1989

The Bank of Canada first introduced Canada Savings Bonds during the First and Second World Wars. At the time, they were known as War Savings Certificates and Victory Bonds and were used to fund the war effort. In 1946, Canada Savings Bonds were used as part of Canada’s Postwar Financing Program. At that time, the government also introduced the sale of bonds through payroll deduction. Canada Savings Bonds proved to be very popular, providing investors with a convenient, flexible and safe investment. Over time the bonds failed to remain competitive with other low-risk investment options, and the high cost of administering the program called into question its relevance. An independent report commissioned by the government in 2004 recommended that the bonds be phased out, however, the government decided to keep the program and make some revisions. As of 2012, Canada Savings Bonds are available exclusively through the payroll savings program, while Canada Premium Bonds (introduced in 1998) are available through financial institutions, dealers and by phone.

Exploring the Current State of Grades 4 to 8 Science Education in Ontario

This study sought to explore the current state of Grades 4 to 8 science education in Ontario from the perspective of Junior/Intermediate (J/I) teachers. The study’s methodology was a sequential 2-phased mixed methods explanatory design denoted as QUAN (qual)  qual. Data were collected from an online survey and follow-up interviews. J/I teachers (N = 219) from 48 school boards in Ontario completed a survey that collected both quantitative and qualitative data. Interviewees were selected from the survey participant population (n = 6) to represent a range of teaching strategies, attitudes toward teaching science, and years of experience. Survey and interview questions inquired about teacher attitudes toward teaching science, academic and professional experiences, teaching strategies, support resources, and instructional time allotments. Quantitative data analyses involved the descriptive statistics and chi-square tests. Qualitative data was coded inductively and deductively. Academic background in science was found to significantly influence teachers’ reported level of capability to teach science. The undergraduate degrees held by J/I science teachers were found to significantly influence their reported levels of capability to teach science. Participants identified a lack of time allocated for science instruction and inadequate equipment and facilities as major limitations on science instruction. Science in schools was reported to be of a “second-tiered” value to language and mathematics. Implications of this study include improving undergraduate and preservice experiences of elementary teachers by supporting their science content knowledge and pedagogical content knowledge.

Probe-level linear model fitting and mixture modeling results in high accuracy detection of differential gene expression

Affiliation: Institut de recherche en immunologie et en cancérologie, Université de Montréal

Propriétés optiques et analytiques des nanotrous : vers la conception de biocapteurs en résonance des plasmons de surface localisés

Les biocapteurs sont utilisés quotidiennement pour déterminer la présence de molécules biologiques dans une matrice complexe, comme l’urine pour les tests de grossesses ou le sang pour les glucomètres. Les techniques courantes pour la détection des autres maladies nécessitent fréquemment le marquage de l’analyte avec une autre molécule, ce qui est à éviter pour fin de simplicité d’analyse. Ces travaux ont pour but la maximisation de la sensibilité d’une surface d’or ou d’argent nanotrouée, afin de permettre la détection de la liaison de molécules biologiques par résonance des plasmons de surface localisés (LSPR), en utilisant la spectroscopie de transmission. Un biocapteur portable, rapide et sans marquage pour quantifier des analytes d’intérêt médical ou environnemental pourrait être construit à partir de ces travaux. Dans l’objectif d’étudier de nombreuses configurations pour maximiser la sensibilité, le temps et le coût des méthodes de fabrication de nanostructures habituelles auraient limité le nombre de surfaces nanotrouées pouvant être étudiées. Un autre objectif du projet consiste donc au développement d’une technique de fabrication rapide de réseaux de nanotrous, et à moindres coûts, basée sur la lithographie de nanosphères (NSL) et sur la gravure au plasma à l’oxygène (RIE). La sensibilité à la variation d’indice de réfraction associée aux liaisons de molécules sur la surface du métal noble et la longueur d’onde d’excitation du plasmon de surface sont influencées par les caractéristiques des réseaux de nanotrous. Dans les travaux rapportés ici, la nature du métal utilisé, le diamètre ainsi que la périodicité des trous sont variés pour étudier leur influence sur les bandes LSPR du spectre en transmission pour maximiser cette sensibilité, visant la fabrication d’un biocapteur. Les surfaces d’argent, ayant un diamètre de nanotrous inférieur à 200 nm pour une périodicité de 450 nm et les nanotrous d’une périodicité de 650 nm démontre un potentiel de sensibilité supérieur.

La cartographie des sites de régulation génétique à partir de données de débalancement allélique

En 1975, Wilson et King ont proposé que l'évolution opère non seulement via des changements affectant la structure des protéines, mais aussi via des mutations qui modifient la régulation génétique. L'étude des éléments régulateurs de l'expression génétique a un rôle important dans la compréhension de l'expression de différentes maladies et de la réponse thérapeutique. Nous avons développé un algorithme bio- informatique qui nous permet rapidement de trouver des sites de régulation génétique à travers tout le génome et pour une grande quantité de gènes. Notre approche consiste à trouver des sites polymorphes (SNPs) qui sont en déséquilibre de liaison avec le débalancement allélique (AI) afin de cartographier la région régulatrice et le site responsable. Notre méthode est avantageuse par rapport à d'autres méthodes, car elle n'a pas besoin des données « phasées». De plus, les données de débalancement allélique ne sont pas affectées par des facteurs externes étant donné qu'ils sont mesurés dans la même cellule. Nous avons démontré que notre approche est fiable et qu'elle peut détecter des sites loin du gène. De plus, il peut être appliqué à des données de génotypage sans avoir besoin de les « phaser » .

Fabrication des films microstructurés et leurs caractéristiques en spectroscopie de résonance des plasmons de surface

Cette thèse caractérise les propriétés optiques des matériaux plasmoniques microstructurés et procède à l’évaluation des paramètres analytiques afin de les employer comme plateforme de biodétection en spectroscopie de résonance des plasmons de surface (SPR). Aux dimensions micrométriques, les matériaux plasmoniques présentent des caractéristiques optiques propres aux nano- et macromatériaux. La cartographie physicooptiques en SPR de matériaux méso- et microscopiques s’est effectuée à l’aide de films structurés de motifs périodiques triangulaires et circulaires fabriqués par une technique modifiée de lithographie par nanosphères (nanosphere lithography, NSL). À partir de cette vue d’ensemble, quelques films structurés ont été sélectionné en fonction d’aspects analytiques tels que la sensibilité et la résolution face aux variations d’indice de réfraction (RI) pour déterminer le potentiel de ces matériaux comme plateforme de biodetection. Les propriétés optiques distinctes des films microstructurés proviennent d’interactions résonantes entre les modes de plasmons de surface (SP) localisé et délocalisé identifiés par la relation de dispersion en SPR ainsi que l’imagerie Raman. Les conditions de résonance des modes SP dépendant de paramètres expérimentaux (λ, θ, η) tel qu’observés numériquement par rigorous coupled wave analysis (RCWA) et empiriquement. Ces travaux démontrent la nature plasmonique distincte des micro-matériaux et leur potentiel d’intégration aux techniques analytiques SPR existantes. Les matériaux plasmoniques micrométriques furent également étudiés pour l’implémentation de la SPR à une pointe de microscopie à force atomique (atomic force microscopy, AFM) combinant ainsi la spectroscopie à l’imagerie topographique. Des travaux préliminaires se sont concentrés sur la signature spectroscopique de leviers en silicium (Si) et en nitrure de silicium (Si3N4), l’impact d’un revêtement d’or sur les pointes et l’influence de milieu environnant. Une image d’origine plasmonique a été obtenue avec des leviers en Si3N4 revêtus d’or en transmission dans un environnement aqueux, indiquant ainsi le potentiel de ces pointes comme micro-biocapteur SPR. Ces résultats préliminaires servent de fondement pour orienter les prochaines investigations dans ce projet.