Wavelet Image Restoration Using Multifractal Priors

Bayesian image restoration has had a long history of successful application but one of the limitations that has prevented more widespread use is that the methods are generally computationally intensive. The authors recently addressed this issue by developing a method that performs the image enhancement in an orthogonal space (Fourier space in that case) which effectively transforms the problem from a large multivariate optimization problem to a set of smaller independent univariate optimization problems. The current paper extends these methods to analysis in another orthogonal basis, wavelets. While still providing the computational efficiency obtained with the original method in Fourier space, this extension allows more flexibility in adapting to local properties of the images, as well as capitalizing on the long history of developments for wavelet shrinkage methods. In addition, wavelet methods, including empirical Bayes specific methods, have recently been developed to effectively capture multifractal properties of images. An extension of these methods is utilized to enhance the recovery of textural characteristics of the underlying image. These enhancements should be beneficial in characterizing textural differences such as those occurring in medical images of diseased and healthy tissues. The Bayesian framework defined in the space of wavelets provides a flexible model that is easily extended to a variety of imaging contexts.Comment: 19 pages, 4 figure

A statistical method (cross-validation) for bone loss region detection after spaceflight.

Astronauts experience bone loss after the long spaceflight missions. Identifying specific regions that undergo the greatest losses (e.g. the proximal femur) could reveal information about the processes of bone loss in disuse and disease. Methods for detecting such regions, however, remains an open problem. This paper focuses on statistical methods to detect such regions. We perform statistical parametric mapping to get t-maps of changes in images, and propose a new cross-validation method to select an optimum suprathreshold for forming clusters of pixels. Once these candidate clusters are formed, we use permutation testing of longitudinal labels to derive significant changes

Spatially Extended fMRI Signal Response to Stimulus in Non-Functionally Relevant Regions of the Human Brain: Preliminary Results

The blood-oxygenation level dependent (BOLD) haemodynamic response function (HDR) in functional magnetic resonance imaging (fMRI) is a delayed and indirect marker of brain activity. In this single case study a small BOLD response synchronised with the stimulus paradigm is found globally, i.e. in all areas outside those of expected activation in a single subject study. The nature of the global response has similar shape properties to the archetypal BOLD HDR, with an early positive signal and a late negative response typical of the negative overshoot. Fitting Poisson curves to these responses showed that voxels were potentially split into two sets: one with dominantly positive signal and the other predominantly negative. A description, quantification and mapping of the global BOLD response is provided along with a 2 × 2 classification table test to demonstrate existence with very high statistical confidence. Potential explanations of the global response are proposed in terms of 1) global HDR balancing; 2) resting state network modulation; and 3) biological systems synchronised with the stimulus cycle. Whilst these widespread and low-level patterns seem unlikely to provide additional information for determining activation in functional neuroimaging studies as conceived in the last 15 years, knowledge of their properties may assist more comprehensive accounts of brain connectivity in the future

Queer as a Political Concept

The subject of this study is the term: queer which I analyse as a political concept. In many English-speaking countries queer has been a common abusive term for homosexuals and other sexually non-normative individuals. From around the end of the 1980s the term was picked up by many activists and academics as a tool for political engagement. Initially queer was politicized in the context of the AIDS crisis but soon afterwards, the term was used to address political, social and cultural marginalization of sexual minorities. Queer has ever since remained one of the most significant concepts in contemporary sexual minority politics. I examine how queer became a powerful political signifier and I study political messages that the term carried. My study focuses on multiple uses of queer , rising from various forms of direct political activism to numerous academic publications. I argue that the term often functioned as a type of alternative identity, a basis of community, an incitement for political action and even a philosophical category. Rather than trying to establish common elements between the uses of queer , I present the multiplicity of routes by which queer was mobilized politically. The research here described investigates an underexplored topic in the academic literature, as most publications to this day offer analyses of queer theories or activism, while the very concept queer has often been overlooked. By discussing the political uses of the term, my study therefore goes beyond the scope of so-called queer theory. Instead, I analyse these theories from a novel standpoint, reflecting on the conceptual politics that queer performs in various texts. This thesis traces the conceptual change that queer underwent to become an umbrella term for various political claims. At the end of the 1980s, queer was used by ACT UP activists and, subsequently, by other groups and individuals to express disagreement with mainstream U.S. sexual politics. From about 1991 queer enters academia. I study texts by Teresa de Lauretis, Michael Warner, Judith Butler, Eve Kosofsky Sedgwick, Lee Edelman and several others. I offer conceptual analyses of their use of queer as a political concept. I also engage in discussion about the consequences of certain political claims for sexual minorities. My findings indicate that queer was one of the central concepts used in academic debates concerning sexual minorities in the 1990s. For instance, Teresa de Lauretis used the term to criticize the previous lesbian and gay discourse and to incite development of a new language that would accommodate the multiplicity of experiences of lesbian and gay people. Judith Butler used the term to address intersections of sex, class and race. For Eve Kosofsky Sedgwick queer is a specific deconstructive term, whereas for Jack (Judith) Halberstam it is an anarchic term that opens a horizon of an alternative politics. Over the past recent decades there have been countless uses of queer as a political concept. My thesis analyses the most influential ones. I present a variety of political purposes the concept serves and point out the importance of this concept within contemporary sexual minority movement and thought.Tämän tutkimuksen aihe on termi queer , jota analysoin poliittisena käsitteenä. Monissa englanninkielissä maissa queer on ollut yleinen halventava termi homoseksuaaleista ja muista ei-normatiivisista yksilöistä. 1980-luvun loppupuolelta lähtien useat aktivistit ja tutkijat alkoivat käyttää käsitettä poliittisena työkaluna. Alun perin queer politisoitui AIDS-kriisin yhteydessä, mutta pian termiä käytettiin kuvaamaan seksuaalivähemmistöjen poliittista, sosiaalista ja kulttuurista marginalisaatiota. Queer on aina siitä lähtien ollut yksi merkittävimmistä käsitteistä nykyaikaisessa seksuaalivähemmistöjen politiikassa. Tutkin kuinka queerista tuli voimakas poliittinen merkitsijä ja tutkin poliittisia viestejä, joita kyseinen termi sisälsi. Tutkimukseni keskittyy queerin moninaisiin käyttötapoihin, jotka juontuvat niin erilaisista suoran poliittisen aktivismin muodoista kuin lukuisista akateemisista julkaisuistakin. Väitän, että termi toimi usein eräänlaisena vaihtoehtoisena identiteettinä, yhteisön perustana ja kutsuna poliittiseen toimintaan ja jopa filosofisena kategoriana. Sen sijaan että yrittäisin osoittaa yhteiset tekijät queerin eri käyttötapojen kesken, esittelen niitä moninaisia reittejä, joiden kautta queer mobilisoitiin poliittisesti. Tässä kuvailtava tutkimus selvittää aiemmin akateemisessa kirjallisuudessa tutkimatonta aihetta, sillä useimmat julkaisut ovat tähän mennessä tarjonneet analyyseja queer-teoriasta tai aktivismista, sen sijaan itse queerin käsite on usein ohitettu. Tutkimukseni tarkastelee termin poliittista käyttöä ja siten ylittää niin kutsutun queer-teorian alueen. Sen sijaan analysoin näitä teorioita uudesta näkökulmasta, pohtien käsitteellistä politiikkaa, jota queer toteuttaa erilaisissa teksteissä. Tämä tutkielma jäljittää niitä käsitteellisiä muutoksia, joita queer kävi läpi tullakseen kattotermiksi erilaisille poliittisille vaatimuksille. 1980-luvun lopulla queeria käyttivät ACT UP -aktivistit ja sittemmin muut ryhmät ja yksilöt ilmaistakseen vastalauseensa Yhdysvaltain valtavirran seksuaalipolitiikalle. Noin vuonna 1991 queer tuli akateemiseen maailmaan. Tutkin tekstejä Teresa de Lauretikselta, Michael Warnerilta, Judith Butlerilta, Eve Kosofsky Sedgwickiltä, Lee Edelmanilta ja useilta muilta. Tarjoan käsiteanalyysin heidän tavoistaan käyttää queeria poliittisena käsitteenä. Osallistun myös keskusteluun niistä poliittisista seurauksista, jotka kytkeytyvät tiettyihin seksuaalivähemmistöjen poliittisiin vaatimuksiin. Tutkimustulokseni osoittavat, että queer oli yksi keskeisimmistä käsitteistä akateemisessa keskustelussa koskien seksuaalivähemmistöjä 1990-luvulla. Esimerkiksi Teresa de Lauretis käytti termiä kritisoidakseen aiempaa lesbo- ja homodiskurssia ja kannustaakseen sellaisen uuden kielen kehittämiseen, joka ottaisi huomioon lesbojen ja homojen moninaiset kokemukset. Judith Butler käytti termiä keskustellakseen sukupuolen, luokan ja rodun risteymistä. Eve Kosofsky Sedgwickille queer oli tietty dekonstruktiivinen termi, kun taas Jack (Judith) Haberstamille se on anarkistinen termi, joka avaa horisontin vaihtoehtoiselle politiikalle. Viime vuosikymmenten aikana queeria on käytetty lukemattomilla tavoilla poliittisena käsitteenä. Tutkielmani analysoi kaikkein vaikutusvaltaisimpia käyttötapoja. Esittelen erilaisia poliittisia päämääriä, joita käsite palvelee, ja osoitan tämän käsitteen tärkeyden nykyaikaisessa seksuaalivähemmistöjen liikkeessä ja ajattelussa

Porin Proteins in Mitochondria from Rat Pancreatic Islet Cells and White Adipocytes

The binding of hexo-/glucokinase and glycerol kinase to mitochondria via the channel forming protein, porin, in pancreatic islet β-cells and adipocytes, was recently proposed to participate in nutritional signaling, glucose sensing, and the control of high-energy phosphate distribution and oxidative phosphorylation. In this study we demonstrate that polyclonal antisera against purified rat liver porin recognize unique proteins in rat pancreatic islets, adipocytes, and RINm5F cells, each with an apparent Mr about 2000 smaller than that of liver porin. Immunoblotting of subcellular fractions, the purity of which has been controlled by the distribution of marker proteins, revealed the mitochondrial localization of the cross-reacting proteins. Their enrichment with a method used for the purification of porin proteins, the characteristic behavior during isoelectric focusing, and the specific binding of rat liver hexokinase and glycerol kinase to phospholipid vesicles containing the purified cross-reacting β-cell or adipocyte proteins strongly suggest their identity with mitochondrial porin. The subtle differences in the apparent Mr and charge heterogeneity raise the possibility of the existence of porin isoforms expressed in a tissue-specific manner. Anti-porin antisera coimmunoprecipitated hexo-/glucokinase from rat insulinoma cell (RINm5F) and adipocyte mitochondria as determined by subsequent immunoblotting of the immunoprecipitates with polyclonal antisera against yeast hexokinase and rat liver glucokinase, respectively. This indicates that some rat pancreatic glucokinase (54 kDa) and liver hexokinase (102 kDa), respectively, is bound to mitochondrial porin. The major portion of the bound fraction is released from mitochondria after treatment with glucose 6-phosphate. Incubation of RINm5F and fat cells with the insulin releasing sulfonylurea drug, glimepiride (20 nM and 5 μM, respectively) for 30 min reduces the amount of hexo-/glucokinase associated with mitochondria and porin to about 50-30%. The reduced kinase binding activity of porin is preserved after isolation of porin from glimepiride-treated cells, reconstitution into phospholipid vesicles and assaying for glucose 6-phosphate inhibitable binding of rat liver hexokinase. The sulfonylurea tolbutamide (20 μM and 5 mM) is significantly less effective. The sulfonylurea-induced inhibition of hexo-/glucokinase binding to mitochondrial porin does not require glucose metabolism or Ca2+ influx into the cells. These data suggest that the sulfonylurea glimepiride, which is thought to inhibit the ATP-regulated K+-channel in β-cells, may have, in addition, an intracellular site of action in pancreatic islet and adipocyte cells at the level of regulation of gluco-/hexokinase binding to mitochondrial porin

Transport activity and presence of ClC-7/Ostm1 complex account for different cellular functions

Loss of the lysosomal ClC-7/Ostm1 2Cl(-)/H(+) exchanger causes lysosomal storage disease and osteopetrosis in humans and additionally changes fur colour in mice. Its conversion into a Cl(-) conductance in Clcn7(unc/unc) mice entails similarly severe lysosomal storage, but less severe osteopetrosis and no change in fur colour. To elucidate the basis for these phenotypical differences, we generated Clcn7(td/td) mice expressing an ion transport-deficient mutant. Their osteopetrosis was as severe as in Clcn7(-/-) mice, suggesting that the electric shunt provided by ClC-7(unc) can partially rescue osteoclast function. The normal coat colour of Clcn7(td/td) mice and their less severe neurodegeneration suggested that the ClC-7 protein, even when lacking measurable ion transport activity, is sufficient for hair pigmentation and that the conductance of ClC-7(unc) is harmful for neurons. Our in vivo structure-function analysis of ClC-7 reveals that both protein-protein interactions and ion transport must be considered in the pathogenesis of ClC-7-related diseases