Energy Management System for LVDC Island Networks

Recent developments in power electronics technology have made it possible to develop competitive and reliable low-voltage DC (LVDC) distribution networks. Further, islanded microgrids—isolated small-scale localized distribution networks— have been proposed to reliably supply power using distributed generations. However, islanded operations face many issues such as power quality, voltage regulation, network stability, and protection. In this thesis, an energy management system (EMS) that ensures efficient energy and power balancing and voltage regulation has been proposed for an LVDC island network utilizing solar panels for electricity production and lead-acid batteries for energy storage. The EMS uses the master/slave method with robust communication infrastructure to control the production, storage, and loads. The logical basis for the EMS operations has been established by proposing functionalities of the network components as well as by defining appropriate operation modes that encompass all situations. During loss-of-powersupply periods, load prioritizations and disconnections are employed to maintain the power supply to at least some loads. The proposed EMS ensures optimal energy balance in the network. A sizing method based on discrete-event simulations has also been proposed to obtain reliable capacities of the photovoltaic array and battery. In addition, an algorithm to determine the number of hours of electric power supply that can be guaranteed to the customers at any given location has been developed. The successful performances of all the proposed algorithms have been demonstrated by simulations.

Piirilevyn suunnittelu suurelle virralle DC/DC-muuntimeen

Ajoneuvoissa, kuten busseissa, käytetään yleensä 24 VDC järjestelmiä ja tämä ei muutu myöskään sähköajoneuvojen kohdalla. Sähköajoneuvoissakin tarvitaan siis 24 VDC matalajänniteakustoja valoille, pyyhkijöille ja muille matalan jännitteen järjestelmille. Lisäksi sähköajoneuvoissa on esimerkiksi ilmastointi ja paineilmankompressori, jotka tarvitsevat taajuusmuuttajan pyörittämään niitä. Tässä työssä suunnitellaan suuren virran piilevy DC/DC-muuntimeen, joka on osa ajoneuvokäyttöön suunnitellun invertterin ja DC/DC-muuntimen yhdistelmälaitetta. Työn pääpaino on piirilevyn suunnittelussa, mutta työssä kerrotaan lyhyesti koko laitteen kytkentä ja käyttötarkoitus. Työssä kerrotaan myös tehopiirilevylle tulevien komponenttien valinta, mitoitus ja jäähdytys. Käydään läpi suuren virran piirilevysuunnittelun mitoitusperiaatteet ja mitä seikkoja siinä erityisesti tulee ottaa huomioon. Lisäksi käsitellään piirilevyn liityntöjä ja virtakiskojen lämpenemää virranahtautumisen takia. Suunniteltua piirilevyä mitataan ja sen toimintaa kokeillaan prototyyppilaitteessa. Protoyyppilaitteella havaitaan virtakiskojen lämpenevän liikaa ja huomataan ongelma kytkenssä. Kytkentää korjattiin ja toimintaa analysoitiin uudestaan, jonka jälkeen havaittiin piirilevyn lämpenemän tippuneen 20 °C. Lopputuloksena piirilevyn lämpenemä, korjatulla kytkennällä, on suunnitellun mukainen. Lopussa esitetään piirilevyn korvaamista moduuliratkaisulla laitteen parantamiseksi sarjatuotantoon.

Sedentary behaviour and health with special reference to obesity and fatty liver in early midlife. The Cardiovascular risk in Young Finns Study

Background: Physical inactivity and positive energy balance pose a risk to health. They increase the risk of obesity and associated non-communicable diseases. Recently, also sedentary behaviour has been associated with obesity and non-communicable diseases. Nevertheless, it has been unclear which type of sedentary behaviour is the most harmful. It is also unknown whether the relationship of sedentary behaviour with obesity is truly independent of other factors, for example physical activity and diet. Longitudinal data are limited, and the direction of causality and the mechanism of action are still unknown. Aims: The aim of this study was 1) to identify the type of sedentary behaviour having the strongest association with obesity, 2) to explore the causal relationship of sedentary behaviour and weight increase, and 3) to additionally, investigate the relationship of sedentary behaviour with fatty liver. These were studied in cross-sectional and/or longitudinal settings using data from the Cardiovascular Risk in Young Finns Study. Special emphasis was put on the evaluation of a wide range of other lifestyle factors and risks for obesity and fatty liver. Subjects: 2,060 subjects (aged 33-50 years in 2011, of which 55 % were female) from the Cardiovascular Risk in Young Finns Study participating in follow-ups in 2001, 2007, and 2011. Measures: Self-reported time spent in various types of sedentary behaviour (I), or TV viewing time (I-III). Measured body weight, height and waist circumference (I-III), and genetic variants for high BMI (I). Fasting plasma concentrations of gamma-glutamyltransferase enzyme and triglyceride, calculated Fatty Liver Index (based on gamma-glutamyltransferase and triglyceride concentration, BMI and waist circumference), and the amount of intrahepatic fat measured with ultrasound (III). Self-reported leisure-time physical activity and active commuting, occupational physical activity, energy intake, diet, alcohol consumption, smoking, socioeconomic status, and sleep duration as possible confounders were considered (I-III). Results: TV viewing is the sedentary behaviour type that has the strongest association with obesity. Sedentary behaviour (TV viewing) precedes weight increase, and not the other way around. Sedentary behaviour (TV viewing) is associated with increased risk of fatty liver. Conclusions: Sedentary behaviour (especially high TV viewing time) is associated with increased risks of obesity and fatty liver. Intervention studies are needed to assess whether reduction of TV time would prevent obesity and fatty liver.

Sähköautojen akkuteknologioiden tilannekatsaus

Tämän kandidaatintyön tavoitteena oli tutkia sähköautoissa käytettäviä akkuteknologioita ja verrata niiden ominaisuuksia keskenään sekä sähköautojen asettamien akkuvaatimusten kanssa. Akkuteknologiakartoituksen ja ominaisuusvertailun avulla tutkimuksessa oli tarkoitus selvittää sähköautojen akkujen kehitystä menneestä nykyhetkeen ja luoda katsaus akkuteknologian tulevaisuuteen. Tutkimuksessa painotettiin akkujen suorituskykynäkökulmaa, mutta tutkimuksessa otettiin kantaa myös eri akkuteknologioiden turvallisuuteen, ympäristötekijöihin ja hintaan. Työ toteutettiin kirjallisuustutkimuksena ja lähteinä käytettiin alan kirjallisuutta, IEEE artikkeleita, tutkimusraportteja ja verkkodokumentteja. Lisäksi tutkimuksessa hyödynnettiin akku- ja sähköautovalmistajilta saatavaa tietoa, johon suhtauduttiin varauksin. Tutkimuksessa kävi ilmi, että erilaisia litiumioniakkuteknologioita käytetään tällä hetkellä eniten sekä täyssähköautoissa että pistokehybrideissä. Huomattiin, että akkujen suorituskyvyn kehittyminen on nopeutunut viime vuosina. Erityisesti akkujen energianvarastointikykyyn vaikuttavat ominaisenergiatasot ovat kasvaneet selkeästi. Nykyisen kehittyneen litiumioniakkuteknologian todettiin täyttävän jo osittain lähivuosien suorituskykytavoitteet. Tutkimuksessa tultiin siihen tulokseen, että litiumrikkiakkuteknologia voi korvata litiumioniakkuteknologian ainakin täyssähköautoissa parempien ominaisenergiatasojen ja halvempien valmistuskustannuksien takia. Myös litiumilma-akkuteknologialla havaittiin olevan mahdollisuuksia haastaa muut litiumakkuteknologiat seuraavalla vuosikymmenellä. Tutkimuksen johtopäätöksenä todetaan, että sähköautot voivat kaupallistua laajemmin lähivuosina akkujen suorituskykyominaisuuksien kehittyessä jatkuvasti. Suorituskykyominaisuuksien parantuminen tulee todennäköisesti johtamaan siihen, että täyssähköautot yleistyvät enemmän ja pistokehybridit tulevat jäämään sähköautojen välivaiheeksi. Uusien akkuteknologioiden käyttöönotto kaupallisiin sähköautoihin voi viedä kuitenkin odotettua kauemmin, sillä akut tarvitsevat huolellista testausta ja käyttöönotto edellyttää, että kaikki ominaisuudet ovat vaaditulla tasolla.

Brasil (1955-2005): 25 anos de catching up, 25 anos de falling behind

Brazil (1955-2005): 25 years of catching-up, 25 years of falling behind. The present paper discusses the Brazilian industrial development under a neo-schumpeterian perspective in the period after 1955. The hypothesis is that, in the last 50 years, Brazil spent the first 25 years catching up and, next, the following 25 years falling behind. The 1955-1980 period, by means of international funding, allowed catching up with the paradigm in maturation within the fourth technological revolution. However, in this period, it was determined the main debilitating elements for the country's entrance in the new techno-economical paradigm of the fifth technological revolution which emerged in the middle of the 70s. It is in the strategy to internationalize the economy, granting the mutinational companies the key-sectors of the national economy dynamics during the catching up period, the main element of dependence in the journey that conditions the current performance, responsible for technology subordination and keeps the Brazilian economy with low dynamism.

Operatiivinen säteilysuojelu Posivan kapselointi- ja loppusijoituslaitoksella

Olkiluodon ja Loviisan ydinvoimalaitoksilla syntyvä käytetty ydinpolttoaine tullaan kapseloimaan ja loppusijoittamaan Posiva Oy:n kapselointi- ja loppusijoituslaitoksella, joka rakennetaan Olkiluotoon. Käytetyn polttoaineen käsittelyssä on huomioitava säteilytyöhön liittyviä säteilysuojelunäkökohtia. Kapseloinnissa ja loppusijoituksessa käsitellään vaarallisia säteilylähteitä, joista merkittävimmät ovat käytetty ydinpolttoaine ja täyden loppusijoituskapselin röntgentarkastuslaitteisto. Posivan laitosten käyttötoiminnalle muodostetaan tässä diplomityössä säteilysuojelun vaatimusmäärittely. Kapseloinnin ja loppusijoituksen säteilytyövaiheet käsitellään yksitellen säteilysuojelun näkökulmasta. Työvaiheille määritetään tarpeelliset säteilysuojelutoimenpiteet ja työvaiheiden suorittamisen säteilysuojeluvaatimukset. Molempien laitosten valvonta-aluejärjestelyjä ja säteilyolosuhteiden vyöhykejakoa tarkennetaan. Työssä määritetään vyöhyke- ja aluerajoilla vaadittavat säteilysuojelutoiminnot sekä kontaminaationhallinnan laatuvaatimukset. Työssä käsitellään myös operatiivisen säteilysuojelun toimenpiteiden laatuvaatimuksia ja tarvittavaa säteilysuojelun sisäistä ohjeistoa. Työn tuloksena on kapselointi- ja loppusijoituslaitoksen käyttötoiminnan operatiivisten säteilysuojelutoimenpiteiden kuvaus. Kapselointi- ja loppusijoituslaitosten säteilysuojelua toteutetaan käyttövaiheen työnsuunnittelulla, operatiivisilla säteilysuojelutoimilla ja rakenteellisin keinoin. Työntekijöiden säteilyannokset minimoidaan välttämällä oleskelua kohonneen säteilytason alueilla. Kapselin röntgentarkastuslaitteiston käytön säteilyturvallisuus on varmistettava ja laitosten käyttötoiminta ei saa aiheuttaa työntekijöille sisäistä säteilyannosta. Useista työvaiheista ja käyttötoiminnan poikkeustilanteista on tehtävä jatkoanalyyseja työntekijöiden säteilysuojelun näkökulmasta.

Parameter estimation for Chaotic or Stochastic Dynamics

Since its discovery, chaos has been a very interesting and challenging topic of research. Many great minds spent their entire lives trying to give some rules to it. Nowadays, thanks to the research of last century and the advent of computers, it is possible to predict chaotic phenomena of nature for a certain limited amount of time. The aim of this study is to present a recently discovered method for the parameter estimation of the chaotic dynamical system models via the correlation integral likelihood, and give some hints for a more optimized use of it, together with a possible application to the industry. The main part of our study concerned two chaotic attractors whose general behaviour is diff erent, in order to capture eventual di fferences in the results. In the various simulations that we performed, the initial conditions have been changed in a quite exhaustive way. The results obtained show that, under certain conditions, this method works very well in all the case. In particular, it came out that the most important aspect is to be very careful while creating the training set and the empirical likelihood, since a lack of information in this part of the procedure leads to low quality results.

Reuse of electric vehicle battery in uninterruptible power supply

Tässä diplomityössä tarkasteltiin Nissan Leaf -sähköauton käytetyn litiumakun soveltuvuutta UPS-varavirtalaitteen energialähteeksi. Kun akku on heikentynyt niin ettei sen kapasiteetti enää ole riittävä autokäyttöön, sitä voidaan kuitenkin vielä hyödyntää muissa sovelluksissa, kuten UPS-laitteessa. Työ sai alkunsa osana GreenDataNet-projektia, jossa pyritään kehittämään datakeskuksiin ympäristöä vähemmän kuormittavia ratkaisuja käyttämällä uusiutuvia energialähteitä, akkujen uusiokäytöllä, sekä energianhallinnan optimoinnilla. Työssä käytiin läpi akun ja sen ohjausjärjestelmän ominaisuuksia, kerrottiin UPS:in ohjelmistoon tehdyistä muutoksista sekä esitettiin testitulokset. Lopputuloksena todettiin akun sopivan muuten hyvin UPS-käyttöön, mutta vaadittu päivittäinen kennojännitteiden tasaus ja sen aiheuttama katkos energian saatavuuteen heikentää UPSin käyttövarmuutta kuorman suojauksessa. Lopussa esitettiin muutamia ehdotuksia tämän ongelman korjaamiseksi.

Kulutuselektroniikan akkujen tekniset ominaisuudet ja markkinaosuudet 2015

Työssä tutkittiin kirjallisuustyönä akkuteknologian nykytilaa ja markkinoita kulutuselektroniikan osalta. Työssä tehtiin myös katsaus potentiaalisiin tulevaisuuden akkuteknologioihin. Työssä havaittiin, että kulutuselektroniikassa ainoat suuresti käytetyt akkutyypit ovat nikkelimetallihybridi- (NiMH) ja litiumioniakut (Li-ion). Tärkeimpänä ominaisuutena kulutuselektroniikassa akuilla yleensä pidetään kapasiteettia, jossa Li-ion akut ovat selvästi parempia jopa kaksinkertaisen energiatiheyden takia. Li-ion akuilla voidaan saavuttaa myös moninkertainen käyttöikä lataussykleinä ja moninkertainen purkausvirta, riippuen käytetystä katodimateriaalista. NiMH akuilla etuna on lähinnä halvempi hinta ja parempi turvallisuus. Toisaalta myös pieni jännite voidaan laskea hyväksi puoleksi, koska NiMH akuilla voidaan korvata kertakäyttöisiä alkaliparistoja. Vuonna 2012 Li-ion akkuja myytiin kapasiteetissa mitattuna jopa kahdeksan kertaa enemmän kuin NiMH akkuja ja myyntimäärien ennustetaan myös kasvavan tulevaisuudessa. Liion akkujen myyntimääristä suurin osa oli kulutuselektroniikan käyttökohteisiin ja jopa kaksi kolmasosaa oli kannettavien tietokoneiden ja kännyköiden akkuja. Uusia akkuteknologioita ja Li-ion akkujen parannuksia on paljon kehitteillä, mutta suurimman potentiaalin ja myös suuret ongelmat kaupallistumiseen omaa litium-ilma akut. Lyhyemmällä aikavälillä potentiaalisia teknologioita ovat litium-rikki akut, sekä nykyisiin Li-ion akkuihin kehitteillä olevat anodimateriaalit kuten esim. pii ja alumiini/titaani, joiden ongelmiin on löydetty ratkaisuja nanoteknologiasta.

Remote Observation of Radioactive Permit-Required Confined Spaces – Case: Posiva Oy’s Fuel Handling Cell

Posiva Oy’s final disposal facility’s encapsulation plant will start to operate in the 2020s. Once the operation starts, the facility is designed to run more than a hundred years. The encapsulation plant will be first of its kind in the world, being part of the solution to solve a global issue of final disposal of nuclear waste. In the encapsulation plant’s fuel handling cell the spent nuclear fuel will be processed to be deposited into the Finnish bedrock, into ONKALO. In the fuel handling cell, the environment is highly radioactive forming a permit-required enclosed space. Remote observation is needed in order to monitor the fuel handling process. The purpose of this thesis is to map (Part I) and compare (Part II) remote observation methods to observe Posiva Oy’s fuel handling cell’s process, and provide a possible theoretical solution for this case. Secondary purpose for this thesis is to provide resources for other remote observation cases, as well as to inform about possible future technology to enable readiness in the design of the encapsulation plant. The approach was to theoretically analyze the mapped remote observation methods. Firstly, the methods were filtered by three environmental challenges. These are the high levels of radiation, the permit-required confined space and the hundred year timespan. Secondly, the most promising methods were selected by the experts designing the facility. Thirdly, a customized feasibility analysis was created and performed on the selected methods to rank the methods with scores. The results are the mapped methods and the feasibility analysis scores. The three highest scoring methods were radiation tolerant camera, fiberscope and audio feed. A combination of these three methods was given as a possible theoretical solution for this case. As this case is first in the world, remote observation methods for it had not been thoroughly researched. The findings in this thesis will act as initial data for the design of the fuel handling cell’s remote observation systems and can potentially effect on the overall design of the facility by providing unique and case specific information. In addition, this thesis could provide resources for other remote observation cases.

A physical activity intervention in a workplace setting

Physical inactivity poses a huge burden on Canada's health care system and is detrimental to the health of Canadians (Katzmarzyk & Janssen, 2004). Walking is a viable option for individuals to become physically active on a daily basis and is in fact the most commonly reported leisure time physical activity. It has been associated with many health benefits including weight loss/weight control, reduced risk of coronary artery disease and diabetes, lowered blood pressure, and improved psychological wellbeing (Brisson & Tudor-Locke, 2004). Specifically, individuals' stage of change, selfefficacy and health related quality of life (HRQL) are three psychological constructs that can be greatly improved with increased physical activity (Dishman, 1991; Penedo & Dahn, 2005; Poag & McAuley, 1992). Public health physical activity recommendations exist but many individuals find these difficult to meet due to overly busy lifestyles (Public Health Agency of Canada, 2003). Pedometers are inexpensive devices that can monitor individual bouts of walking so that the incorporation of physical activity into one's daily life is more plausible. They are also excellent tools for motivation, goalsetting, and immediate feedback (Brisson & Tudor-Locke, 2004). Since many people spend a large proportion of their time at their places of employment, workplaces have begun to be a common site for the development of physical activity interventions. These programs have been growing in popUlarity and have shown numerous benefits for both employees and employers (Voit, 2001). The purpose of the current study was to implement and evaluate the use of a pedometer-based physical activity intervention incorporating goal-setting and physical activity logs in a workplace setting, and to examine the relationship between different types of self-efficacy (task, barrier, and scheduling) and different phases of the intervention. Twenty male participants from a local steel manufacturing plant who exhibited health risk factors (e.g. hypertension, diabetes, etc.) were assigned to one of two groups (group A or group B). All participants were asked to wear pedometers on their waists, record their daily steps, set goals that were outlined on a step-tracking sheet (detennined by their baseline number of steps), and keep track of their work days, wakelbed time, sedentary time, and time spent doing other physical activity. Group A began the intervention immediately following the baseline measures, whereas group B continued with their regular routine for 4 weeks before beginning. Physiological measures (height, weight, blood pressure, relative body fat, waist and hip circumference, and body mass index) were taken and a battery of questionnaires that assessed barrier, task and scheduling self-efficacy, HRQL, and stage of change administered at baseline, week 5 (end of intervention for group A), week 9 (end of intervention for group B; follow-up for group A) and week 13 (follow-up for both groups). Results showed that this workplace physical activity intervention was successful at increasing the participants' daily steps, that task self-efficacy is a significant predictor of participants' exercise adherence during the initial stages of participation (intervention phase), and that the participants felt that this intervention was effective. Finally, further exploratory analyses showed that this intervention was effective for all participants, but most valuable for participants most in need of improvement - that is, those who were most sedentary prior to the intervention. This intervention is an inexpensive use of simple and effective tools (e.g. pedometers), has the potential to attract a wide variety of participants and become a pennanent part of any health promotion initiative.

Calculation of nondifferential properties for atomic ground states /

A new method for sampling the exact (within the nodal error) ground state distribution and nondiflPerential properties of multielectron systems is developed and applied to firstrow atoms. Calculated properties are the distribution moments and the electronic density at the nucleus (the 6 operator). For this purpose, new simple trial functions are developed and optimized. First, using Hydrogen as a test case, we demonstrate the accuracy of our algorithm and its sensitivity to error in the trial function. Applications to first row atoms are then described. We obtain results which are more satisfactory than the ones obtained previously using Monte Carlo methods, despite the relative crudeness of our trial functions. Also, a comparison is made with results of highly accurate post-Hartree Fock calculations, thereby illuminating the nodal error in our estimates. Taking into account the CPU time spent, our results, particularly for the 8 operator, have a relatively large variance. Several ways of improving the eflSciency together with some extensions of the algorithm are suggested.

Foraging ecology and parental behaviour in the common tern (Sterna hirundo)

One component of successful parenting is related to efficiency in foraging behaviour. The relationships among chick feeding, the size and type of food package, and length of parental foraging trips has not been well studied in seabirds. In addition, relatively few data have been collected on the activities of seabirds when foraging away from the nest site. The objectives of this study were: (1) to contrast productivity, feeding rate, and attendance patterns of individuals carrying a novel transmitter with a control group of birds; (2) to use radio-telemetry to assess the variability in foraging locations within and between individual male Common Terns; (3) to determine the seasonal variation in chick diet; (4) to determine for each transmittered bird, the relationships among the foraging patterns, parental behaviour, and seasonal reproductive success. The study took place over two years (1990-91) on a concrete breakwater 1 km offshore on Lake Erie near Port Colbome, Ontario. Ten pairs of terns in 1990 and 12 pairs in 1991 were radio-tracked by boat or car during the chick rearing stage. Concurrent behavioural observations documented the time each sex spent foraging or at the nest. The frequency and prey species composition of feeds to chicks were also recorded. The transmitters had negligible effects on the feeding frequency and brood attendance patterns of transmitter carrying birds. Peak nesting transmittered birds in 1990 and 1991 exhibited some inter-individual variability in foraging locations, however intraindividual variability was low. Birds foraged primarily to the west and northwest of the colony. Late nesters exhibited greater inter-individual variability, however intra-individual variability remained low for most birds. Neither group demonstrated sufficient variability to support the regular use of this colony as an "information centre". Individual transmittered birds had unique and predictable foraging patterns, and corresponding differences in feeding frequencies and brood attendance patterns, yet productivity was essentially equal between nests due to the impact and importance of stochastic events. Individuals that were recaptured in 1991 exhibited very similar foraging patterns to 1990, suggesting littie variability between years. Conservation of foraging patterns between years may have potential implications for mate choice decisions in future breeding seasons. Prey species delivered to chicks differed between morning and evening for peak and late nesters in 1990, but not 1991. Peak nesters in 1990 fed significantiy more Rainbow Smelt fOsmerus mordM) than Emerald Shiner (Notropis atherinoidesV this trend was reversed for late nesters who also fed large numbers of unidentified larval fish. No significant differences were found in 1991. Seasonal changes in prey species delivered to chicks is believed to be attributable to the temperature tolerances of the smelt and shiners, and the presence of large schools of larval fish during the late nesting season.

Trends in fish prey capture by common terns following zebra mussel invasion : do terns track fish species abundance? /

The Common Tern (Sterna hirundo) is a ground nesting colonial seabird. Terns rely primarily on small prey fishes which they obtain through plunge diving for their survival as well as the survival of their offspring during the breeding season. The zebra mussel (Dreissena polymorpha) is a small bivalve mollusk that invaded North American waters in the late 1980's. Through its suspension feeding, the zebra mussel has the ability to alter the entire aquatic ecosystem, ultimately leading to a reduction in pelagic organisms including small prey fish. The objective of the study was to determine what (if any) indirect effects the invasion of the zebra mussel has had on fish prey captured by terns. The study took place in two separate two-year periods, 1990-91 and 1995-96 on a concrete breakwall off the north shore of Lake Erie near Port Colborne, Ontario. Daily nest checks revealed clutch initiation dates, egg-laying chronology, hatching success and morphological egg characteristics (length and breadth). Behavioural observations included time each sex spent in attendance with its brood, the frequency of feeding chicks and the prey species composition and size fed to chicks as well as to females (courtship feeding). Egg sizes did not differ between study periods, nor did feeding rates to chicks, suggesting that food was not a limiting resource. Terns spent less time with their broods (more time foraging) in the 1995-96 period. However, they also had significantly larger broods and fledged more offspring. The time of each individual foraging trip decreased, suggesting that fish were easier to obtain in 1995 and 1996. Lastly, kleptoparasitism rates decreased, suggesting that the costs of foraging (time, energy) actually decreased as fewer birds adopted this strategy to compensate for what I assumed to be a lack of available food (fish). The only significant difference between the periods of 1990, 1991 and 1995, 1996 was a change in diet. Terns delivered significantly fewer rainbow smelt and more emerald shiner in 1995 and 1996. However, the average size of fish delivered did not change. Thus, there was little impact on prey captured by Common Terns in Lake Erie since the invasion of the zebra mussel.

A dose-response investigation of the attentional blink during sleep restriction /

Recent dose-response sleep restriction studies, in which nightly sleep is curtailed to varying degrees (e.g., 3-, 5-, 7-hours), have found cumulative, dose-dependent changes in sleepiness, mood, and reaction time. However, brain activity has typically not been measured, and attentionbased tests employed tend to be simple (e.g., reaction time). One task addressing the behavioural and electrophysiological aspects of a specific attention mechanism is the Attentional Blink (AB), which shows that the report accuracy of a second target (T2) is impaired when it is presented soon after a first target (Tl). The aim of the present study was to examine behavioural and electrophysioiogical responses to the AB task to elucidate how sleep restriction impacts attentional capacity. Thirty-six young-adults spent four consecutive days and nights in a sleep laboratory where sleep, food, and activity were controlled. Nightly sleep began with a baseline sleep (8 hours), followed by two nights of sleep restriction (3,5 or 8 hours of sleep), and a recovery sleep (8 hours). An AB task was administered each day at 11 am. Results from a basic battery oftests (e.g., sleepiness, mood, reaction time) confirmed the effectiveness of the sleep restriction manipulation. In terms of the AB, baseline performance was typical (Le., T2 accuracy impaired when presented soon after Tl); however, no changes in any AB behavioural measures were observed following sleep restriction for the 3- or 5-hour groups. The only statistically significant electrophysiological result was a decrease in P300 amplitude (for Tl) from baseline to the second sleep restriction night for the 3-hour group. Therefore, following a brief, two night sleep restriction paradigm, brain functioning was impaired for the TI of the AB in the absence of behavioural deficit. Study limitations and future directions are discussed.