Localization of type 1 diabetes susceptibility to the MHC class I genes HLA-B and HLA-A

The major histocompatibility complex (MHC) on chromosome 6 is associated with susceptibility to more common diseases than any other region of the human genome, including almost all disorders classified as autoimmune. In type 1 diabetes the major genetic susceptibility determinants have been mapped to the MHC class II genes HLA-DQB1 and HLA-DRB1 (refs 1–3), but these genes cannot completely explain the association between type 1 diabetes and the MHC region4, 5, 6, 7, 8, 9, 10, 11. Owing to the region's extreme gene density, the multiplicity of disease-associated alleles, strong associations between alleles, limited genotyping capability, and inadequate statistical approaches and sample sizes, which, and how many, loci within the MHC determine susceptibility remains unclear. Here, in several large type 1 diabetes data sets, we analyse a combined total of 1,729 polymorphisms, and apply statistical methods—recursive partitioning and regression...

Ruumiillinen esine, materiaalinen suku : Tutkimus Pyhä Anna itse kolmantena -aiheisista keskiajan puuveistoksista Suomessa

Embobied Object, Material Family. Late-Medieval Wood Sculptures Depicting Saint Anne with the Virgin and Child in Finland Saint Anne, the mother of the Virgin Mary, was one of the most popular saints in Western Europe in the late Middle Ages. She was often depicted with two other figures, the Virgin and the Christ Child (Anna Selbdritt). The dissertation examines the polychrome wood sculptures showing this motif, with a special focus on those remaining in Finland. It investigates the meanings these sculptures had to their observers in the fifteenth-century Finland. The study sheds light to important material heritage which is little known and offers new insights into the cult and imagery of the holy grandmother. Methodologically the study is based on iconology and post-formalist art history, and it appropriates concepts such as spatiality, sanctity, corporeality, and gender. Taking a comparative approach it knits together larger tendencies and local people and incidents. By conflating methodological domains it renews the ways how fragmentary wood sculptures, lacking documentary written sources, can be contextually interpreted and comprehended. The sculptures are analyzed from three angles. Firstly, the study explores the sculptures by focusing on their materiality and facture, which is to consider them as records of their own making. The analysis provides new information concerning the quantity, location, and current condition of the sculptures and it also elucidates problems regarding attribution, dating, display, and craftsmanship. The book presents the results of the empirical study of 45 Saint Anne groups; these works are individually described in the large Appendix. Secondly, the works are contextualized to the specific historical conditions in which they were observed. The study discusses closely the circumstances in the Turku Cathedral around the shrine of Saint Anne, the popular belief, and the piety of individual persons. The sculptures, deemed as the embodiments of the holy characters, interacted with the devotees. Thirdly, the works are examined within the wider theological and ideological currents of the era centered on the body and Incarnation. Saint Anne with the Virgin and Child motif demonstrated the Carnal Trinity, the motherly side of the Holy Trinity. The dissertation argues that Saint Anne was interpreted as the female counterpart or, in a mythical sense, wife of God. Furthermore, the Child s implicit, simultaneous presence as a suffering or dead man imbues the sculptures with a sense of the Passion, thus associating them with the pietà and the Mater dolorosa motifs. The naked Christ Child underlines him as the offering and, eventually, the Eucharistic wafer. The study suggests that the sculptures mediate continuity and the bloodline between the generations by the intertwined and repeated gestures, clothing and positions of the portrayed figures. Regardless of the ostensible homeliness of the sculptures, so readily reiterated by earlier scholars, these sculptures represented creation and birth through the carnal yet holy mothers.

Approaching Sacred Pregnancy : The Cult of the Visitation and Narrative Altarpieces in Late Fifteenth-Century Florence

The study focuses on the Visitation as a narrative subject of altarpieces in late fifteenth-century Florence. Although the Visitation was a well-known story in both verbal and visual representations since the early medieval period, it became a popular subject of altarpieces only towards the end of the fifteenth century. In this study, the first part provides an overview of the complex religious and historical background to an emerging cult of the Visitation. Devotional practices focusing on the Visitation belong in a context of late medieval Marian devotion and in 1389 a new feast of the Visitation was introduced into the liturgical calendar of the Catholic Church. Because of the ongoing schism within the Catholic Church, the feast was not unanimously accepted across Western Europe until the later part of the fifteenth century. Contrary to a widely disseminated view, the feast of the Visitation cannot be associated with Franciscan spirituality, but was rather a clearly defined Dominican project that primarily emphasised the importance of peace and unity within the Christian Church. Simultaneously with the gradual acceptance of the new feast, visual representations of the Visitation began to appear at the centre of altarpieces. The Visitation exemplifies an increasing preference for narrative subjects within the genre of the altarpiece. The second part of the study presents an analysis of the concept of the narrative altarpiece and highlights the complexities involved in combining a narrative content with the traditional devotional function of the altarpiece. In detailed case studies some prominent art works produced in Florence between 1490 and 1503 are discussed within a framework of contextual analysis, narrative theory and iconography. Altarpieces by Domenico Ghirlandaio, Piero di Cosimo and Mariotto Albertinelli represent visual manifestations of a cult of the Visitation with roots in late medieval devotional practices. At the same time, the altarpieces highlight the multiple functions of altarpieces in a culture where art works responded to a variety of social and religious needs. Building on earlier studies, each case study presents new insights and evidence not considered in previous art historical research.

Tuuleen piirrän nimeni : Daniel Urwindin fragmentaarinen omaelämäkerta Bo Carpelanin romaanissa Alkutuuli

Tutkielma käsittelee Bo Carpelanin romaania Alkutuuli (Urwind 1993) päähenkilö Daniel Urwindin fragmentaarisesti kerrottuna elämäntarinana. Kyse on kahdella aikatasolla etenevästä fiktiivisestä omaelämäkerrasta, joka perustuu viikottaisiin päiväkirjamerkintöihin. Daniel hahmottaa identiteettiään tilaan kytkeytyneiden muistojen sekä oman nimensä avulla leikaten samalla kerronnan jatkuvuuden. Tutkimusongelmana on hahmottaa Danielin kerronnan tavat, kirjoittamisen syyt sekä prosessiin lopputulos. Menneisyyteen kohdistuvan minä-kerronnan analyysi perustuu Dorrit Cohnin Transparent minds -teoksen käsitteistöön. Alkutuulessa esiintyy muistikerronnan ja muistimonologin epäsäännöllistä vuorottelua. Niiden osana on edesmenneiden läheisten upotettuja monologeja, joiden takaa kuultaa Danielin ääni: monologit ovat Danielin kuvittelemia tai referoimia puheita ja ajatuksia, joiden esittäjä on hänen yksinäisen keskustelunsa toinen osapuoli. Omaelämäkertaa käsittelevinä teoreettisina lähteinä ovat ensisijaisesti Päivi Kososen artikkelit sekä hänen tutkimuksensa Elämät sanoissa. Tutkielman tulkinnan kannalta keskeisessä asemassa ovat Bo Carpelanin essee- ja kaunokirjallinen tuotanto. Kirjoittamisen lähtökohtana on päähenkilön identiteettiä horjuttava elämänvaihe. Vaimo Marian lähdettyä vuodeksi Amerikkaan Daniel pyrkii löytämään oman kielensä ja luomaan muistojensa avulla eheämmän kuvan itsestään. Prosessiin kytkeytyy keskeisesti tila - Danielin kulkiessa talossaan, joka on hänen lapsuudenkotinsa, aistitodellisuus toimii mieleenpalauttajana: äänet ja tuoksut johdattavat hänet elämään menneisyyden muistoja uudelleen nykyhetkessä. Samalla talo ja huoneet personifioituvat ja minuus alkaa rakentua tilan kaltaiseksi. Uusien ovien ja huoneiden löytyminen symboloi Danielin muistojen selkeytymistä ja itseymmärryksen syvenemistä. Kirjoittamisen voi tulkita olevan psykoanalyyttinen prosessi, jossa omaelämäkerran minä keskustelee menneisyyden minänsä kanssa. Puhuja odottaa vastausta toiselta, vaikka vastaus löytyy paradoksaalisesti itsestä. Omaelämäkerran moniäänisyyttä korostavat edesmenneiden läheisten läsnäolo, Danielin eri ikävaiheiden identiteetit ja kaksoisolentojen hahmoissa esiintyvät minuudet. Kirjoittamisen avulla Daniel pyrkii pääsemään etäämmälle itsestään ja saavuttamaan minättömyyden tilan, jota käsitellään John Keatsilta peräisin olevan käsitteen "negatiivinen kyky" avulla. Alkutuuli on taiteilijaromaani, jossa taiteilijuutta edustavat siivet ja lentäminen kytkeytyvät mielikuvitukseen ja uusiutumiseen. Danielin tie taiteilijuutta edeltävään minättömyyteen on kuitenkin vaikea ja monet merkit viittaavat diletantin kohtaloon. Unenomaisen logiikan omaavan, fragmentaarisen kerronnan takaa on hahmotettavissa myös lainalaisuuksia. Muiden henkilöiden lyhyet elämäkerrat ovat heidän haavansa paljastavia episodeja, jotka muuttuvat osaksi Danielin elämäntarinaa. Danielin kirjallinen omakuva on montaasi, jossa eri tasossa olevat elementit, nykyhetki ja menneisyys, mielikuvitus, unet ja upotetut monologit rinnastuvat samaan tasoon. Daniel peilaa elettyä ja koettua koomisen peilirakenteen avulla, jossa hänen elämäänsä osallisena olleet menneisyyden henkilöt kulkevat narrikulkueen mukana. Toive eheästä minäkuvasta osoittautuu kuitenkin mahdottomaksi merkityssulkeuman todenvastaisuuden vuoksi. Urwind-nimen pohdinnasta liikkeelle lähtenyt omaelämäkerta päättyy syklistä liikettä mukaillen tilanteeseen, jossa päähenkilö hyväksyy elämän käsittämättömyyden ja luottaa omassa nimessään piilevään voimaan, tuuleen, viitaten samalla myös romaanin nimeen. Avainsanat: Bo Carpelan - muistot - tila - fragmentaarisuus - fiktiivinen omaelämäkerta

Kohti täydellistä hengellisyyttä : Pyhiinvaellus imitaatioperformanssina kolmen keskiaikaisen mystikkonaisen hagiografiassa

Pro gradu -tutkielmassa tarkastellaan kolmen keskiaikaisen mystikkonaisen – Angela Folignolaisen (1248–1309), Dorothea Montaulaisen (1347–1394) ja Margery Kempen (1373–1440) – pyhiinvaelluksilla suorittamien ruumiillisten ja henkisten imitaatioperformanssien suhdetta julkiseen tilaan. Imitaatioperformansseilla viitataan kyseisten naisten harjoittamaan Kristuksen, Neitsyt Marian ja Maria Magdaleenan seuraamiseen. Tutkimuksessa pohditaan kirjallisten representaatioiden valossa performansseja seuranneiden aikalaisten mahdollisia reaktioita ja sitä, vakuuttivatko mystikkojen performanssit yleisönsä. Tutkimuskysymysten kautta valotetaan myös keskiaikaisia käsityksiä sukupuolesta ja sukupuolirooleista. Tutkimuksen pääasiallisena lähdeaineistona käytetään kyseisten naisen pyhimyselämäkertoja. Niiden lisäksi tukeudutaan myös sellaiseen 1200–1400-luvuilla tuotettuun englannin-, ranskan- ja galician-portugalinkieliseen kaunokirjallisuuteen, josta löytyy kuvauksia naispyhiinvaeltajista. Teoreettisena lähtökohtana tutkimuksessa sovelletaan antropologista teoriaa pyhiinvaelluksesta julkisena performanssina, jonka tarkoituksena on rakentaa ja vahvistaa esittäjän identiteettiä. Mystikkonaisten performansseja analysoidaan lisäksi tilan teorioiden valossa. Pääasiallisesti kyseiset teoriat ovat sosiologisia ja antropologisia, joskin tutkimuksessa käytetään myös tutkijan omia julkista tilaa jäsentäviä termejä. Yhtä lailla hyödynnetään folkloristista teoriaa siirtymäriiteistä. Kirjallisten representaatioiden kohdalla analyysin työkaluina käytetään puolestaan kirjallisuustieteilijöiden satiirisen ironian mekanismeja ja funktioita käsitteleviä teorioita. Pro gradu -tutkielmassa päädytään kolmenlaisiin johtopäätelmiin. Ensinnäkin lähdeaineistosta käy ilmi, että Angela Folignolaisen, Dorothea Montaulaisen ja Margery Kempen performanssien suhde julkiseen tilaan oli looginen. Ulospäin näkyvät ruumiilliset performanssit suoritettiin usein sellaisessa julkisessa tilassa, jossa potentiaalista yleisöä oli tarjolla eniten. Ulospäin vain vähän näkyvät henkiset performanssit puolestaan tapahtuivat usein tilassa, jossa yleisön vähyyttä kompensoi vahva pyhyyden tuntu. Pyhiinvaellus tarjosikin naisille mahdollisuuden toteuttaa mystiikan nk. toista vaihetta, osittain myös kolmatta, ja vahvistaa siten täydelliseen hengellisyyteen pyrkivän hengellisen maallikkonaisen identiteettiä. Lähdeaineistosta käy toiseksi ilmi se, että nykytutkimuksessa on painotettu liian vähän ruumiillisuuden merkitystä naishengellisyydessä. Etenkin Dorothea Montaulainen seurasi Kristuksen ja Maria Magdaleenan esimerkkiä huomattavan usein kehossa asti tuntuvien performanssien avulla. Kolmas lähdeaineiston paljastama seikka liittyy yleisöön. On mahdollista, että mystikoiden ei onnistunut vakuuttaa performansseja seurannutta oppinutta, ”porvarillista” miesyleisöä. Kirjallisten representaatioiden valossa näyttää siltä, että se ei välttämättä hyväksynyt maskuliiniseksi koetussa julkisessa tilassa liikkunutta, sukupuolisia rajoja ylittänyttä naista. Mystikot saattoivat myös edustaa seksuaalista uhkaa, sillä yleisö yhdisti julkisessa tilassa liikkuneen naisen ruumiillisuuteen ja aistillisuuteen.

New genetic loci link adipose and insulin biology to body fat distribution

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10−8). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms.

Genetic studies of body mass index yield new insights for obesity biology

Obesity is heritable and predisposes to many diseases. To understand the genetic basis of obesity better, here we conduct a genome-wide association study and Metabochip meta-analysis of body mass index (BMI), a measure commonly used to define obesity and assess adiposity, in up to 339,224 individuals. This analysis identifies 97 BMI-associated loci (P < 5 × 10−8), 56 of which are novel. Five loci demonstrate clear evidence of several independent association signals, and many loci have significant effects on other metabolic phenotypes. The 97 loci account for ~2.7% of BMI variation, and genome-wide estimates suggest that common variation accounts for >20% of BMI variation. Pathway analyses provide strong support for a role of the central nervous system in obesity susceptibility and implicate new genes and pathways, including those related to synaptic function, glutamate signalling, insulin secretion/action, energy metabolism, lipid biology and adipogenesis.

Meta-analysis of telomere length in 19 713 subjects reveals high heritability, stronger maternal inheritance and a paternal age effect

Telomere length (TL) has been associated with aging and mortality, but individual differences are also influenced by genetic factors, with previous studies reporting heritability estimates ranging from 34 to 82%. Here we investigate the heritability, mode of inheritance and the influence of parental age at birth on TL in six large, independent cohort studies with a total of 19 713 participants. The meta-analysis estimate of TL heritability was 0.70 (95% CI 0.64–0.76) and is based on a pattern of results that is highly similar for twins and other family members. We observed a stronger mother–offspring (r=0.42; P-value=3.60 × 10−61) than father–offspring correlation (r=0.33; P-value=7.01 × 10−5), and a significant positive association with paternal age at offspring birth (β=0.005; P-value=7.01 × 10−5). Interestingly, a significant and quite substantial correlation in TL between spouses (r=0.25; P-value=2.82 × 10−30) was seen, which appeared stronger in older spouse pairs (mean age ≥55 years; r=0.31; P-value=4.27 × 10−23) than in younger pairs (mean age<55 years; r=0.20; P-value=3.24 × 10−10). In summary, we find a high and very consistent heritability estimate for TL, evidence for a maternal inheritance component and a positive association with paternal age.

Pilgrimage as a Lifestyle : A Contemporary Greek Nunnery as a Pilgrimage Site

The aim of this research is to present, interpret and analyze the phenomenon of pilgrimage in a contemporary, suburban Greek nunnery, and to elucidate the different functions that the present-day convent has for its pilgrims. The scope of the study is limited to a case nunnery, the convent of the Dormition of the Virgin, which is situated in Northern Greece. The main corpus of data utilized for this work consists of 25 interviews and field diary material, which was collected in the convent mainly during the academic year 2002-2003 and summer 2005 by means of participant observation and unstructured thematic interviewing. It must be noted that most Greek nunneries are not really communities of hermits but institutions that operate in complex interaction with the surrounding society. Thus, the main interest in this study is in the interaction between pilgrims and nuns. Pilgrimage is seen here as a significant and concrete form of interaction, which in fact makes the contemporary nunneries dynamic scenes of religious, social and sometimes even political life. The focus of the analysis is on the pilgrims’ experiences, reflected upon on the levels of the individual, the Church institution, and society in general. This study shows that pilgrimage in a suburban nunnery, such as the convent of the Dormition, can be seen as part of everyday religiosity. Many pilgrims visit the convent regularly and the visitation is a lifestyle the pilgrims have chosen and wish to maintain. Pilgrimage to a contemporary Greek nunnery should not be ennobled, but seen as part of a popular religious sentiment. The visits offer pilgrims various tools for reflecting on their personal life situations and on questions of identity. For them the full round of liturgical worship is a very good reason for going to the convent, and many see it as a way of maintaining their faith and of feeling close to God. Despite cultural developments such as secularization and globalization, pilgrims are quite loyal to the convent they visit. It represents the positive values of ‘Greekness’ and therefore they also trust the nuns’ approach to various matters, both personal and political. The coalition of Orthodoxy and nationalism is also visible in their attitudes towards the convent, which they see as a guardian of Hellenism and as nurturing Greek values both now and in the future.

Association of FOXE1 Polyalanine Repeat Region with Papillary Thyroid Cancer

CONTEXT: Polyalanine tract variations in transcription factors have been identified for a wide spectrum of developmental disorders. The thyroid transcription factor forkhead factor E1 (FOXE1) contains a polymorphic polyalanine tract with 12-22 alanines. Single-nucleotide polymorphisms (SNP) close to this locus are associated with papillary thyroid cancer (PTC), and a strong linkage disequilibrium block extends across this region. OBJECTIVE: The objective of the study was to assess whether the FOXE1 polyalanine repeat region was associated with PTC and to assess the effect of polyalanine repeat region variants on protein expression, DNA binding, and transcriptional function on FOXE1-responsive promoters. DESIGN: This was a case-control study. SETTING: The study was conducted at a tertiary referral hospital. PATIENTS AND METHODS: The FOXE1 polyalanine repeat region and tag SNP were genotyped in 70 PTC, with a replication in a further 92 PTC, and compared with genotypes in 5767 healthy controls (including 5667 samples from the Wellcome Trust Case Control Consortium). In vitro studies were performed to examine the protein expression, DNA binding, and transcriptional function for FOXE1 variants of different polyalanine tract lengths. RESULTS: All the genotyped SNP were in tight linkage disequilibrium, including the FOXE1 polyalanine repeat region. We confirmed the strong association of rs1867277 with PTC (overall P = 1 × 10(-7), odds ratio 1.84, confidence interval 1.31-2.57). rs1867277 was in tight linkage disequilibrium with the FOXE1 polyalanine repeat region (r(2) = 0.95). FOXE1(16Ala) was associated with PTC with an odds ratio of 2.23 (confidence interval 1.42-3.50; P = 0.0005). Functional studies in vitro showed that FOXE1(16Ala) was transcriptionally impaired compared with FOXE1(14Ala), which was not due to differences in protein expression or DNA binding. CONCLUSIONS: We have confirmed the previous association of FOXE1 with PTC. Our data suggest that the coding polyalanine expansion in FOXE1 may be responsible for the observed association between FOXE1 and PTC.

Toisia todellisuuksia, murtumia kielessä ja subjektissa : Mielen sairaus ja kirjoittaminen terapiana Maria Vaaran omaelämäkerrallisessa tuotannossa

Tutkielmassa käsitellään Maria Vaaran (1931 1992) omaelämäkerrallista teossarjaa sekä Vaaran kirjoittamisen terapeuttisia funktioita. Teoksissaan Vaara kuvaa parantumistaan skitsofreniaksi luokitellusta psyykkisestä sairaudesta ja masennuksesta luovan kirjoittamisen sekä psykoterapian avulla. Vaaran kirjoitus lähestyy psykoanalyyttisia teorioita kirjoittamisen terapeuttisista vaikutuksista, mutta myös jälkistrukturalistisia näkemyksiä tekstistä prosessinalaisena, kumouksellisena käytäntönä. Tutkielman keskeiset teoriat tulevat psykoanalyytikko, kielitieteilijä Julia Kristevalta sekä psykoanalyyttisesta ja jälkistrukturalistisesta perinteestä, ja näiden teoreettisten lähestymistapojen avulla tarkastellaan omaelämäkerrallisen kirjoittamisen, subjektiuden sekä kielen ja kirjoittamisen toisiinsa limittyviä teemoja Vaaran tuotannossa. Vaaran omaelämäkerrallinen kirjoittaminen paljastuu tutkielmassa yhtäaikaisesti subjektiutta eheyttäväksi ja hajottavaksi toiminnaksi. Vaaran teokset osoittavat, miten minuus rakentuu erilaisten samastumisten ja erottautumisten kautta, psykoottisten kuvitelmien, hallusinaatioiden ja paranoidien kuvitelmien täyttäessä tekstin. Kirjoittaminen kohtaa ongelman merkityksen epäyhtenevyydestä: siitä, ettei sanoilla koskaan voida täysin tavoittaa omia psykofyysisia kokemuksia tai välittää niitä toisille ihmisille. Kuitenkin Vaaran teosten Maria kirjoittaa kaiken aikaa ja luo kokemuksellisia suhteita toisiin. Mielikuvitus, kirjallisuus ja kirjoittaminen muodostavat avoimen psyykkisen tilan, jossa minuutta voidaan rakentaa. Kirjoittaminen osoittautuu lopulta käytännöksi, jossa esteettinen, terapeuttinen ja eettinen nivoutuvat yhteen. Vaaran teosten Marian harjoittama minuuden analyysi tarjoaa mahdollisuuksia käsitellä vierauden ja toiseuden ilmenemistä omassa itsessä ilmiö, joka Julia Kristevan mukaan mahdollistaa myös niiden todellisten toisten ymmärtämisen, joiden parissa elämme. Vaaran teokset kyseenalaistavat jaottelun terveisiin ja sairaisiin , ne rikkovat toden ja fiktion välisiä rajoja ja käsitystä minuudesta yhtenä ja eheänä. Vaaran tuotanto ei olekaan ainoastaan kuvaus skitsofreniasta ja sen kielestä, vaan siitä, miten minuus ja ilmaisu ylipäänsä rakentuvat suhteessa toisiin ja miten psyykkinen elämä on riippuvaista avoimuudesta erilaisille katkoksille ja murtumille.

The determination of stem cell fate by 3D scaffold structures through the control of cell shape

Stem cell response to a library of scaffolds with varied 3D structures was investigated. Microarray screening revealed that each type of scaffold structure induced a unique gene expression signature in primary human bone marrow stromal cells (hBMSCs). Hierarchical cluster analysis showed that treatments sorted by scaffold structure and not by polymer chemistry suggesting that scaffold structure was more influential than scaffold composition. Further, the effects of scaffold structure on hBMSC function were mediated by cell shape. Of all the scaffolds tested, only scaffolds with a nanofibrous morphology were able to drive the hBMSCs down an osteogenic lineage in the absence of osteogenic supplements. Nanofiber scaffolds forced the hBMSCs to assume an elongated, highly branched morphology. This same morphology was seen in osteogenic controls where hBMSCs were cultured on flat polymer films in the presence of osteogenic supplements (OS). In contrast, hBMSCs cultured on flat polymer films in the absence of OS assumed a more rounded and less-branched morphology. These results indicate that cells are more sensitive to scaffold structure than previously appreciated and suggest that scaffold efficacy can be optimized by tailoring the scaffold structure to force cells into morphologies that direct them to differentiate down the desired lineage. Published by Elsevier Ltd.

Fast Direct Torque Control of an Open-End Induction Motor Drive Using 12-Sided Polygonal Voltage Space Vectors

A torque control scheme, based on a direct torque control (DTC) algorithm using a 12-sided polygonal voltage space vector, is proposed for a variable speed control of an open-end induction motor drive. The conventional DTC scheme uses a stator flux vector for the sector identification and then the switching vector to control stator flux and torque. However, the proposed DTC scheme selects switching vectors based on the sector information of the estimated fundamental stator voltage vector and its relative position with respect to the stator flux vector. The fundamental stator voltage estimation is based on the steady-state model of IM and the synchronous frequency of operation is derived from the computed stator flux using a low-pass filter technique. The proposed DTC scheme utilizes the exact positions of the fundamental stator voltage vector and stator flux vector to select the optimal switching vector for fast control of torque with small variation of stator flux within the hysteresis band. The present DTC scheme allows full load torque control with fast transient response to very low speeds of operation, with reduced switching frequency variation. Extensive experimental results are presented to show the fast torque control for speed of operation from zero to rated.

A Medium-Voltage Inverter-Fed IM Drive Using Multilevel 12-Sided Polygonal Vectors, With Nearly Constant Switching Frequency Current Hysteresis Controller

In this paper, a current error space vector (CESV)-based hysteresis current controller for a multilevel 12-sided voltage space vector-based inverter-fed induction motor (IM) drive is proposed. The proposed controller gives a nearly constant switching frequency operation throughout different speeds in the linear modulation region. It achieves the elimination of 6n +/- 1, n = odd harmonics from the phase voltages and currents in the entire modulation range, with an increase in the linear modulation range. It also exhibits fast dynamic behavior under different transient conditions and has a simple controller implementation. Nearly constant switching frequency is obtained by matching the steady-state CESV boundaries of the proposed controller with that of a constant switching frequency SVPWM-based drive. In the proposed controller, the CESV reference boundaries are computed online, using the switching dwell time and voltage error vector of each applied vector. These quantities are calculated from estimated sampled reference phase voltages. Vector change is decided by projecting the actual current error along the computed hysteresis space vector boundary of the presently applied vector. The estimated reference phase voltages are found from the stator current error ripple and the parameters of the IM.

Nearly Constant Switching Frequency Hysteresis Current Controller with Fast Online Computation of Boundary for a 2-Level Induction Motor Drive

A nearly constant switching frequency current hysteresis controller for a 2-level inverter fed induction motor drive is proposed in this paper: The salient features of this controller are fast dynamics for the current, inherent protection against overloads and less switching frequency variation. The large variation of switching frequency as in the conventional hysteresis controller is avoided by defining a current-error boundary which is obtained from the current-error trajectory of the standard space vector PWM. The current-error boundary is computed at every sampling interval based on the induction machine parameters and from the estimated fundamental stator voltage. The stator currents are always monitored and when the current-error exceeds the boundary, voltage space vector is switched to reduce the current-error. The proposed boundary computation algorithm is applicable in linear and over-modulation region and it is simple to implement in any standard digital signal processor: Detailed experimental verification is done using a 7.5 kW induction motor and the results are given to show the performance of the drive at various operating conditions and validate the proposed advantages.