988 resultados para gap bilinear diffie hellman problem
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I avhandlingen analyseras betydelsen av kön i den vetenskapliga socialpolitiken vid 1900-talets mitt, i synnerhet med fokus på Heikki Waris (1901–1989) produktion. Waris var Finlands första professor i socialpolitik, som efter andra världskriget etablerades som ett akademiskt ämne vid de finländska universiteten, och Waris blev känd som en av tidens främsta auktoriteter på den finländska socialpolitiken. Vid en tid då välfärdsstaten etablerades och samhället genomgick en snabb moderniseringsprocess, fokuserade den socialpolitiska forskningen på problem och frågor som främst ansågs beröra den manliga delen av befolkningen, såsom alkoholkonsumtion och relationer inom det industriella arbetet. Detta trots att de nordiska staterna senare skulle bli kända som så kallade kvinnovänliga välfärdsstater, där frågor om kvinnors position och jämställdhet beaktades. I avhandlingen belyses hur de texter Waris skrev, samt den forskning som han initierade, skapade ideal baserade på sundhet, ekonomiskt ansvarstagande, aktivitet och medvetenhet samt hur dessa ideal var kopplade till män och manlighet. Förutom att visa hur ideal konstruerades, studeras även de olika formerna och funktionerna av kön i den socialpolitiska litteraturen. Behandlades kön endast som demografisk kategori eller fanns det ett djupare intresse för mäns och kvinnors positioner och roller? Vilka förhållanden ville Waris och de andra socialpolitikerna belysa med att lyfta fram frågor om kön i sina texter? Waris var även en auktoritet på den snabba moderniseringsprocess som Finland hade genomgått sedan industrialiseringen vid 1800-talets slut. I avhandlingen argumenteras för att män och kvinnor på varierande sätt blev symboler för samhällelig förändring. ------------------------ Väitöskirjassa tutkitaan sukupuolen merkitystä sosiaalipolitiikan tutkimuksessa 1900-luvun puolivälissä. Lähtökohtana on Heikki Wariksen (1901–1989) tieteellinen tuotanto. Waris toimi Suomen ensimmäisenä sosiaalipolitiikan professorina ja kehitti sosiaalipolitiikkaa akateemisena aiheena Suomessa toisen maailmansodan jälkeen. Waris tunnettiin yhtenä aikansa merkittävimpänä suomalaisen sosiaalipolitiikan asiantuntijana. Hyvinvointivaltion rakentumisaikana sosiaalipolitiikan tutkimus keskittyi miehiin liittyviin ongelmiin ja kysymyksiin, kuten alkoholin kulutukseen. Väitöskirjassa osoitetaan miten Wariksen teksteissä, ja Wariksen ohjaamissa väitöskirjoissa rakennettiin terveellisyydelle, elättäjyydelle, aktiivisuudelle sekä tietoisuudelle pohjautuva ihanne, joka oli kytketty miehiin ja miehuuteen. Lisäksi tutkitaan sukupuolen muotoja ja funktioita sosiaalipoliittisessa kirjallisuudessa. Oliko sukupuoli pelkkä väestöllinen kategoria vai osoittivatko sosiaalipolitiikan tutkijat syvällisempää mielenkiintoa miesten ja naisten asemaa sekä rooleja kohtaan? Mitkä asiat huomioitiin sukupuolen avulla? Waris oli myös industrialismin aiheuttaman yhteiskuntamuutoksen asiantuntija. Väitöskirjassa osoitetaan miten miehiä ja naisia käsiteltiin eri tavalla muutoksen symboleina.
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Det är inte ovanligt att man i organisationer ställs inför problem som inte kan hanteras inom befintlig organisationsstruktur. Skälen kan vara att frågorna har många – ibland konflikterande – dimensioner och perspektiv som samtidigt måste beaktas. I den här avhandlingen studeras vilka tankemönster och föreställningar som fanns när grupper av chefer försökte lösa komplexa problem, som inte hade en naturlig organisatorisk hemvist och hur de omsatte dessa tankemönster i handling. Vad kännetecknade det ledarskap som utövades under problemlösningsprocessen? Avhandlingens empiri hämtas från ledarutvecklingsprogram i två internationellt verksamma företag i Sverige, och omfattar 14 verkliga affärsproblem i dessa företag och den process varigenom de löstes. De 14 seminarierna utgör exempel på hur mångdimensionella frågeställningar framgångsrikt hanteras utanför den befintliga organisationsstrukturen. Studien ger, genom att adressera frågor kring tankesätt och ledningsprocesser, en djupare förståelse för förutsättningarna för detta, och lyfter särskilt fram betydelsen av ett ledarskap som inbegriper begreppen intervention, förmåga och omtolkning. Som ett samlat begrepp introduceras bilden att utöva ledarskapet utifrån ett matrix mind. Att påverka strukturer (i vid mening) och därigenom de förmågor som utvecklas, är del i detta ledarskap. Det sker genom interventioner (ingrepp som påverkar relationer i t ex en grupp) och baserades i den aktuella empirin på uppfattningar om värdet av problematisering, erfarenhetsutbyte och av ett språk, som både beskriver och anger inriktning för aktiviteter. Interventioner i strukturer (och till dem knutna processer) beskriver dock bara delvis detta ledarskap. Att leda med ett matrix mind innefattar också ett nyfiket och kreativt förhållningssätt, och att utifrån detta leda omtolkning av problem. I empirin finns flera exempel på detta. Avhandlingen avser att ge ett bidrag inom såväl organisations- som ledarskapsteori.
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Poster at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014
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Leaf CO2 assimilation (A) as a function of photosynthetic photon flux density (Q) or intercellular CO2 concentration (Ci) and chlorophyll fluorescence measurements were carried out on four tropical woody species growing in forest gap and understorey (Bauhinia forficata Link. and Guazuma ulmifolia Lam. as pioneers, and Hymenaea courbaril L. and Esenbeckia leiocarpa Engl. as non-pioneers). Chlorophyll fluorescence indicated similar acclimation capacities of photochemical apparatus to contrasting light environments irrespective to plant species. Maximum CO2 assimilation and quantum yield derived from A/Q curves indicated higher photosynthetic capacity in pioneer than in non-pioneer species in forest gap. However, the differences among species did not show a straightforward relation with their successional status regarding data derived from A/Q curves under understorey conditions. Both successional groups are able to sustain positive carbon balance under contrasting natural light availabilities, modifying photochemical and biochemical photosynthetic traits with similar phenotypic plasticity capacity.
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Most cells exchange ions and small metabolites via gap junction channels. These channels are made of two hemichannels (connexons), each formed by the radial arrangement of six connexin (Cx) proteins. Connexins span the bilayer four times (M1-M4) and have both amino- and carboxy-termini (NT, CT) at the cytoplasmic side of the membrane, forming two extracellular loops (E1, E2) and one inner (IL) loop. The channels are regulated by gates that close with cytosolic acidification (e.g., CO2 treatment) or increased calcium concentration, possibly via calmodulin activation. Although gap junction regulation is still unclear, connexin domains involved in gating are being defined. We have recently focused on the CO2 gating sensitivity of Cx32, Cx38 and various mutants and chimeras expressed in Xenopus oocytes and studied by double voltage clamp. Cx32 is weakly sensitive to CO2, whereas Cx38 is highly sensitive. A Cx32 chimera containing the second half of the inner loop (IL2) of Cx38 was as sensitive to CO2 as Cx38, indicating that this domain plays an important role. Deletion of CT by 84% did not affect CO2 sensitivity, but replacement of 5 arginines (R) with sparagines (N) at the beginning of CT (C1) greatly enhanced the CO2 sensitivity of Cx32. This suggests that whereas most of CT is irrelevant, positive charges of C1 maintain the CO2 sensitivity of Cx32 low. As a hypothesis we have proposed a model that involves charge interaction between negative residues of the beginning of IL1 and positive residues of either C1 or IL2. Open and closed channels would result from IL1-C1 and IL1-IL2 interactions, respectively
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Gap junctions are constituted by intercellular channels and provide a pathway for transfer of ions and small molecules between adjacent cells of most tissues. The degree of intercellular coupling mediated by gap junctions depends on the number of gap junction channels and their activity may be a function of the state of phosphorylation of connexins, the structural subunit of gap junction channels. Protein phosphorylation has been proposed to control intercellular gap junctional communication at several steps from gene expression to protein degradation, including translational and post-translational modification of connexins (i.e., phosphorylation of the assembled channel acting as a gating mechanism) and assembly into and removal from the plasma membrane. Several connexins contain sites for phosphorylation for more than one protein kinase. These consensus sites vary between connexins and have been preferentially identified in the C-terminus. Changes in intercellular communication mediated by protein phosphorylation are believed to control various physiological tissue and cell functions as well as to be altered under pathological conditions.
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It is well known that saccadic reaction times (SRT) are reduced when the target is preceded by the offset of the fixation point (FP) - the gap effect. Some authors have proposed that the FP offset also allows the saccadic system to generate a separate population of SRT, the express saccades. Nevertheless, there is no agreement as to whether the gap effect and express responses are also present for manual reaction times (MRT). We tested the gap effect and the MRT distribution in two different conditions, i.e., simple and choice MRT. In the choice MRT condition, subjects need to identify the side of the stimulus and to select the appropriate response, while in the simple MRT these stages are not necessary. We report that the gap effect was present in both conditions (22 ms for choice MRT condition; 15 ms for simple MRT condition), but, when analyzing the MRT distributions, we did not find any clear evidence for express manual responses. The main difference in MRT distribution between simple and choice conditions was a shift towards shorter values for simple MRT.
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Gap junctions are clusters of intercellular channels directly connecting the cytoplasm of adjacent cells. These channels are formed by proteins named connexins and are present in all metazoan organisms where they serve diverse functions ranging from control of cell growth and differentiation to electric conduction in excitable tissues. In this overview we describe the presence of connexins in the cardiovascular and lympho-hematopoietic systems giving the reader a summary of the topics to be covered throughout this edition and a historical perspective of the discovery of gap junctions in the immune system.
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The role gap junction channels play in the normal and abnormal functioning of the vascular wall is the subject of much research. The biophysical properties of gap junctions are an essential component in understanding how gap junctions function to allow coordinated relaxation and contraction of vascular smooth muscle. This study reviews the properties thus far elucidated and relates those properties to tissue function. We ask how biophysical and structural properties such as gating, permselectivity, subconductive states and channel type (heteromeric vs homotypic vs heterotypic) might affect vascular smooth muscle tone.
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Connexin43 (Cx43) is a major gap junction protein present in the Fischer-344 rat aorta. Previous studies have identified conditions under which selective disruption of intercellular communication with heptanol caused a significant, readily reversible and time-dependent diminution in the magnitude of a1-adrenergic contractions in isolated rat aorta. These observations have indentified a significant role for gap junctions in modulating vascular smooth muscle tone. The goal of these steady-state studies was to utilize isolated rat aortic rings to further evaluate the contribution of intercellular junctions to contractions elicited by cellular activation in response to several other vascular spasmogens. The effects of heptanol were examined (0.2-2.0 mM) on equivalent submaximal (»75% of the phenylephrine maximum) aortic contractions elicited by 5-hydroxytryptamine (5-HT; 1-2 µM), prostaglandin F2a (PGF2a; 1 µM) and endothelin-1 (ET-1; 20 nM). Statistical analysis revealed that 200 µM and 500 µM heptanol diminished the maximal amplitude of the steady-state contractile responses for 5-HT from a control response of 75 ± 6% (N = 26 rings) to 57 ± 7% (N = 26 rings) and 34.9 ± 6% (N = 13 rings), respectively (P<0.05), and for PGF2a from a control response of 75 ± 10% (N = 16 rings) to 52 ± 8% (N = 19 rings) and 25.9 ± 6% (N = 18 rings), respectively (P<0.05). In contrast, 200 µM and 500 µM heptanol had no detectable effect on the magnitude of ET-1-induced contractile responses, which were 76 ± 5.0% for the control response (N = 38 rings), 59 ± 6.0% in the presence of 200 µM heptanol (N = 17 rings), and 70 ± 6.0% in the presence of 500 µM heptanol (N = 23 rings) (P<0.13). Increasing the heptanol concentration to 1 mM was associated with a significant decrease in the magnitude of the steady-state ET-1-induced contractile response to 32 ± 5% (21 rings; P<0.01); further increasing the heptanol concentration to 2 mM had no additional effect. In rat aorta then, junctional modulation of tissue contractility appears to be agonist-dependent.
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Gap junction channels are sites of cytoplasmic communication between contacting cells. In vertebrates, they consist of protein subunits denoted connexins (Cxs) which are encoded by a gene family. According to their Cx composition, gap junction channels show different gating and permeability properties that define which ions and small molecules permeate them. Differences in Cx primary sequences suggest that channels composed of different Cxs are regulated differentially by intracellular pathways under specific physiological conditions. Functional roles of gap junction channels could be defined by the relative importance of permeant substances, resulting in coordination of electrical and/or metabolic cellular responses. Cells of the native and specific immune systems establish transient homo- and heterocellular contacts at various steps of the immune response. Morphological and functional studies reported during the last three decades have revealed that many intercellular contacts between cells in the immune response present gap junctions or "gap junction-like" structures. Partial characterization of the molecular composition of some of these plasma membrane structures and regulatory mechanisms that control them have been published recently. Studies designed to elucidate their physiological roles suggest that they might permit coordination of cellular events which favor the effective and timely response of the immune system.
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Gap junctions are intercellular channels which connect adjacent cells and allow direct exchange of molecules of low molecular weight between them. Such a communication has been described as fundamental in many systems due to its importance in coordination, proliferation and differentiation. Recently, it has been shown that gap junctional intercellular communication (GJIC) can be modulated by several extracellular soluble factors such as classical hormones, neurotransmitters, interleukins, growth factors and some paracrine substances. Herein, we discuss some aspects of the general modulation of GJIC by extracellular messenger molecules and more particularly the regulation of such communication in the thymus gland. Additionally, we discuss recent data concerning the study of different neuropeptides and hormones in the modulation of GJIC in thymic epithelial cells. We also suggest that the thymus may be viewed as a model to study the modulation of gap junction communication by different extracellular messengers involved in non-classical circuits, since this organ is under bidirectional neuroimmunoendocrine control.
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Pro graduavhanlingens svenska sammanfattning
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Simple manual reaction time (MRT) to a visual target (S2) is shortened when a non-informative cue (S1) is flashed at the S2 location shortly before the onset of S2 (early facilitation). Afterwards, MRT to S2 appearing at the S1 location is lengthened (inhibition of return - IOR). Similar results have been obtained for saccadic reaction time (SRT). Moreover, when there is a temporal gap between offset of the fixation point (FP) and onset of a target (gap paradigm), SRT is shorter than SRT in an overlap paradigm (FP remains on). In the present study, we determined SRT to S2 (10º) after presenting S1 at the same eccentricity (10º) or at a parafoveal position (2º) in the same or in the opposite hemifield. In addition, we employed both gap and overlap paradigms. Twelve subjects were asked not to respond to S1 (2º or 10º) to the right or to the left of FP, but to respond by making a saccadic movement in response to S2. We obtained the following results: 1) a 40-ms gap effect, 2) an interaction between gap effect and IOR, 3) a 39-ms delay (IOR) when S2 appeared at the cued (S1) position, and 4) a smaller (17 ms) but significant inhibition when S1 occurred at 2º in the ipsilateral hemifield. Thus, a parafoveal (2º) S1 elicits an inhibition of SRT towards ipsilateral peripheral targets. Since an inhibition of the ipsilateral hemifield by a 1º eccentric cue has been reported to occur when manual responses are employed, we suggest that the postulated functional link between covert and overt orienting of attention is also valid for parafoveal cues.
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Statins are indicated for preventing cardiovascular disease events. Patients with diabetes have a risk of major cardiovascular events double the risk of their peers without diabetes. Thus, clinical treatment guidelines recommend statins for the management of diabetic dyslipidemia. The evidence base for statin use in cardiovascular disease derives from the randomized controlled statin trials designed to prove statin efficacy under ideal conditions, among a homogenous study population meeting strict trial eligibility criteria. This thesis was implemented as four pharmacoepidemiological statin studies using register data on realworld statin users. The overall purpose was to evaluate the trends, patterns and effectiveness of statin use in everyday life. More specifically, nationwide secular trends in statin use in Finland were analysed, especially among patient groups which had been underrepresented in the statin trials. Furthermore, the benchmarking statin trials in diabetes, the Heart Protection Study and the Collaborative Atorvastatin Diabetes Study, were evaluated for their representativeness for real-world diabetes care with the emphasis placed on adherence to statin use. The association between good adherence and the incidence of major cardiovascular events in the real-world was further investigated in diabetes. These studies demonstrate that statin initiations increased from 1995 to 2005 in Finland. The increase was most pronounced among those aged at least 75 years and was observed already before the publication of rigorous trial data conducted in elderly subjects. Thus, statins seem to have been initiated in clinical practice also going beyond the strict trial eligibility criteria. Nonetheless, low adherence to statin use among the real-world patients with diabetes was found not only to limit the representativeness of the trials for clinical care but also to attenuate in all likelihood their benefits in the real-world. In fact, good adherence to statin use was found to associate with a decreased risk for major cardiovascular events in patients with diabetes. In conclusion, these studies highlight the importance of good adherence to statin use in clinical practice in order to obtain the full therapeutic value demonstrated in the statin trials. Simply increasing the number of statin users will not alone suffice in sharing our common resources appropriately.