953 resultados para model categories homotopy theory quillen functor equivalence derived adjunction cofibrantly generated


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In this paper we examine whether access to markets had a significant influence onmigration choices of Spanish internal migrants in the inter-war years. We perform astructural contrast of a New Economic Geography model that focus on the forwardlinkage that links workers location choice with the geography of industrial production,one of the centripetal forces that drive agglomeration in the NEG models. The resultshighlight the presence of this forward linkage in the Spanish economy of the inter-warperiod. That is, we prove the existence of a direct relation between workers¿ localizationdecisions and the market potential of the host regions. In addition, the direct estimationof the values associated with key parameters in the NEG model allows us to simulatethe migratory flows derived from different scenarios of the relative size of regions andthe distances between them. We show that in Spain the power of attraction of theagglomerations grew as they increased in size, but the high elasticity estimated for themigration costs reduced the intensity of the migratory flows. This could help to explainthe apparently low intensity of internal migrations in Spain until its upsurge during the1920s. This also explains the geography of migrations in Spain during this period,which hardly affected the regions furthest from the large industrial agglomerations (i.e.,regions such as Andalusia, Estremadura and Castile-La Mancha) but had an intenseeffect on the provinces nearest to the principal centres of industrial development.

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The process of free reserves in a non-life insurance portfolio as defined in the classical model of risk theory is modified by the introduction of dividend policies that set maximum levels for the accumulation of reserves. The first part of the work formulates the quantification of the dividend payments via the expectation of their current value under diferent hypotheses. The second part presents a solution based on a system of linear equations for discrete dividend payments in the case of a constant dividend barrier, illustrated by solving a specific case.

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In this paper we examine whether access to markets had a significant influence onmigration choices of Spanish internal migrants in the inter-war years. We perform astructural contrast of a New Economic Geography model that focus on the forwardlinkage that links workers location choice with the geography of industrial production,one of the centripetal forces that drive agglomeration in the NEG models. The resultshighlight the presence of this forward linkage in the Spanish economy of the inter-warperiod. That is, we prove the existence of a direct relation between workers¿ localizationdecisions and the market potential of the host regions. In addition, the direct estimationof the values associated with key parameters in the NEG model allows us to simulatethe migratory flows derived from different scenarios of the relative size of regions andthe distances between them. We show that in Spain the power of attraction of theagglomerations grew as they increased in size, but the high elasticity estimated for themigration costs reduced the intensity of the migratory flows. This could help to explainthe apparently low intensity of internal migrations in Spain until its upsurge during the1920s. This also explains the geography of migrations in Spain during this period,which hardly affected the regions furthest from the large industrial agglomerations (i.e.,regions such as Andalusia, Estremadura and Castile-La Mancha) but had an intenseeffect on the provinces nearest to the principal centres of industrial development.

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Lettuce greenhouse experiments were carried out from March to June 2011 in order to analyze how pesticides behave from the time of application until their intake via human consumption taking into account the primary distribution of pesticides, field dissipation, and post-harvest processing. In addition, experimental conditions were used to evaluate a new dynamic plant uptake model comparing its results with the experimentally derived residues. One application of imidacloprid and two of azoxystrobin were conducted. For evaluating primary pesticide distribution, two approaches based on leaf area index and vegetation cover were used and results were compared with those obtained from a tracer test. High influence of lettuce density, growth stage and type of sprayer was observed in primary distribution showing that low densities or early growth stages implied high losses of pesticides on soil. Washed and unwashed samples of lettuce were taken and analyzed from application to harvest to evaluate removal of pesticides by food processing. Results show that residues found on the Spanish preharvest interval days were in all cases below officially set maximum residue limits, although it was observed that time between application and harvest is as important for residues as application amounts. An overall reduction of 40–60% of pesticides residues was obtained from washing lettuce. Experimentally derived residues were compared with modeled residues and deviate from 1.2 to 1.4 for imidacloprid and azoxystrobin, respectively, presenting good model predictions. Resulting human intake fractions range from... for imidacloprid to ... for azoxystrobin.

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This thesis concentrates on the topological defects of spin-1 and spin-2 Bose-Einstein condensates, the ground states of spin-3 condensates, and the inert states of spinor condensates with arbitrary spin. Our work is based on the description of a spinor condensate of spin-S atoms in terms of a state vector of a spin-S particle. The results of the homotopy theory are used to study the existence and structure of the topological defects in spinor condensates. We construct examples of defects, study their energetics, and examine how their stability is affected by the presence of an external magnetic field. The ground states of spin-3 condensates are calculated using analytical and numerical means. Special emphasis is put on the ground states of a chromium condensate, whose dependence on the magnetic dipole-dipole interaction is studied. A simple geometrical method for the calculation of inert states of spinor condensates is presented. This method is used to find candidates for the ground states of spin-S condensates.

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Tutkimuksen tarkoituksena on selvittää mitkä ovat tiedonkäsittelyn haasteet organisaation eri toimintaympäristöissä. Tutkimuksen teoreettisina lähtökohtina ovat tietojohtamisen kolmiulotteinen organisaatiomalli sekä dissipatiivisen ja integroivan viestinnän kehikko. Tutkimuksen käytännönläheisessä osassa tarkastellaan kohdeorganisaation tiedonkulun nykytilaa ja haasteita eri osastoilla. Lisäksi kartoitetaan,mitä tiedonvaihdon välineitä käytetään sekä minkälaisia liikkumista helpottaviaja mahdollistavia tekijöitä eri toimintaympäristöissä ilmenee. Havaituista teemoista luotiin kaksi kuviota, jotka kuvaavat nyky- ja tavoitetilaa kolmiulotteisessa organisaatiossa. Viestinnän näkökulmasta havaintoja luokiteltiin organisaatioviestinnän kaksoisfunktion, laadullisten ominaisuuksien kehyksessä. Lisäksi jaoteltiin, mitä dissipatiivisen ja integroivan viestinnän elementtejä nousi esiin. Nykykäytännöistä löytyneitä elementtejä verrattiin tavoitetilaan. Kohdeorganisaation tarkastelu kolmiulotteisen organisaation ja viestinnän teorioiden pohjalta nosti esiin samansuuntaisia tuloksia. Kehitystarpeiden tunnistaminen mahdollistaa sisäisen viestinnän kehittämisen, minkäjälkeen viestintää tällä hetkellä haittaavat elementit voivat muuttua sitä tukeviksi.

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Adenylate kinases (AKs) are phosphotransferases that regulate the cellular adenine nucleotide composition and play a critical role in the energy homeostasis of all tissues. The AK2 isoenzyme is expressed in the mitochondrial intermembrane space and is mutated in reticular dysgenesis (RD), a rare form of severe combined immunodeficiency (SCID) in humans. RD is characterized by a maturation arrest in the myeloid and lymphoid lineages, leading to early onset, recurrent, and overwhelming infections. To gain insight into the pathophysiology of RD, we studied the effects of AK2 deficiency using the zebrafish model and induced pluripotent stem cells (iPSCs) derived from fibroblasts of an RD patient. In zebrafish, Ak2 deficiency affected hematopoietic stem and progenitor cell (HSPC) development with increased oxidative stress and apoptosis. AK2-deficient iPSCs recapitulated the characteristic myeloid maturation arrest at the promyelocyte stage and demonstrated an increased AMP/ADP ratio, indicative of an energy-depleted adenine nucleotide profile. Antioxidant treatment rescued the hematopoietic phenotypes in vivo in ak2 mutant zebrafish and restored differentiation of AK2-deficient iPSCs into mature granulocytes. Our results link hematopoietic cell fate in AK2 deficiency to cellular energy depletion and increased oxidative stress. This points to the potential use of antioxidants as a supportive therapeutic modality for patients with RD.

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Let $X$ be a smooth complex algebraic variety. Morgan showed that the rational homotopy type of $X$ is a formal consequence of the differential graded algebra defined by the first term $E_{1}(X,W)$ of its weight spectral sequence. In the present work, we generalize this result to arbitrary nilpotent complex algebraic varieties (possibly singular and/or non-compact) and to algebraic morphisms between them. In particular, our results generalize the formality theorem of Deligne, Griffiths, Morgan and Sullivan for morphisms of compact Kähler varieties, filling a gap in Morgan"s theory concerning functoriality over the rationals. As an application, we study the Hopf invariant of certain algebraic morphisms using intersection theory.

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Teollisuuden palvelut tuottavat tulevaisuudessa yhä suuremman osan yritysten liikevaihdosta ja tämän vuoksi niiden systemaattinen kehittäminen yrityksessä on erityisen tärkeää. Tutkimuksen tavoitteena on luoda teorian pohjalta malli, jonka avulla mekatroniikkaklusterin yritykset voivat analysoida tarjottavia palveluitaan asiakkaan näkökulmasta. Tutkimuksessa pyritään myös selvittämään empiirisesti mallin soveltuvuus palvelutarjonnan kehittämiseen tutkimuksessa mukana oleville erikokoisille yrityksille. Tutkimuksen teoreettisessa osassa luodaan katsaus yrityksen kasvustrategioihin. Palveluiden innovaatio- sekä kehitysprosessit käydään lyhyesti läpi, sekä esitetään lähtökohtia, miten yritykset voivat siirtyä tuotetarjoajasta palveluntarjoajaksi. Teoriaosassa käydään läpi QFD -malli, jota voidaan käyttää hyödyksi kun analysoidaan asiakkaan palvelutarpeita ja priorisoidaan yrityksen resursseja. QFD -mallin lisäksi esitellään myös muita laatutyökaluja sekä asiakkaan tarpeiden selvitysmenetelmiä, joita yritys voi käyttää hyödykseen QFD -mallin kanssa. Synteesiosassa esitellään ensin MS Excel -pohjainen QFD -malli. Mallin käyttö-kokeilu toteutetaan työpaja tyylisessä kokouksessa, ja tutkimustulokset kerätään havainnoimalla, teemahaastattelulla sekä kyselyn avulla.

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Sähkömarkkinalain uudistuminen syksyllä 2013 aiheutti sähköverkkoyhtiöille velvoitteen parantaa sähköverkkoja siten, että ne täyttävät uuden lain mukaiset keskeytysaikavaatimukset. Laissa asemakaava-alueilla sallitaan enintään 6 tunnin mittainen sähkönjakelunkeskeytys ja haja-asutusalueella 36 tunnin keskeytys. Diplomityössä kehitetään ElMil Oy:lle palvelumalli, jonka avulla pyritään parantamaan sähköverkkojen säävarmuutta ja arvioimaan parannuksien aiheuttamia taloudellisia vaikutuksia verkkoyhtiön kannattavuuteen verkkoliiketoiminnan valvontamallin kautta. Työn teoriaosiossa käydään läpi uuden sähkömarkkinalain muutoksia toimitusvarmuuden kannalta sekä avataan verkkoliiketoiminnan valvontamallin komponentteja ja sitä kuinka niitä on hyödynnetty tässä työssä. Kyseisiä tietoja hyödynnetään case-tarkastelussa, jossa testataan kehitetyn palvelumallin toimivuutta Järvi-Suomen Energia Oy:n sähkönjakeluverkon kahden sähköaseman jakeluverkkojen kokoisella alueella. Tarkastelualueen sähkönjakeluverkolle tehdään suurhäiriömalli, jonka perusteella arvioidaan vaadittavaa säävarman verkon osuutta, jotta sähkömarkkinalain vaatimukset täyttyvät. Alueen investointikohteet optimoidaan kannattavuuden perusteella, jolloin saadaan kustannustehokas investointiohjelma tiettyjen reunaehtojen puitteissa. Lisäksi suurhäiriömallin parametreja varioidaan herkkyystarkasteluissa. Työn lopputuloksena saadaan ElMil Oy:lle kehitettyä palvelumalli. Case-tarkasteluissa havaitaan, että investointikustannukset nousevat merkittävästi. Verkkoliiketoiminnan valvontamallin kannustinvaikutuksista ja sallitusta tuotosta saadaan hyvä näkemys. Herkkyystarkasteluista nähdään, että suurhäiriömalli on hyvin riippuvainen valituista parametreista, jolloin niiden valintaan tulee kiinnittää huomiota

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Retaining players and re-attracting switching players has long been a central topic for SNG providers with regard to the post-adoption stage of playing an online game. However, there has not been much research which has explored players’ post-adoption behavior by incorporating the continuance intention and the switching intention. In addition, traditional IS continuance theories were mainly developed to investigate users’ continued use of utilitarian IS, and thus they may fall short when trying to explain the continued use of hedonic IS. Furthermore, compared to the richer literature on IS continuance, far too little attention has been paid to IS switching, leading to a dearth of knowledge on the subject, despite the increased incidence of the switching phenomenon in the IS field. By addressing the limitations of prior literature, this study seeks to examine the determinants of SNG players’ two different post-adoption behaviors, including the continuance intention and the switching intention. This study takes a positivist approach and uses survey research method to test five proposed research models based on Unified Theory of Acceptance and Use of Technology 2; Use and Gratification Theory; Push-Pull-Mooring model; Cognitive Dissonance Theory; and a self-developed model respectively with empirical data collected from the SNG players of one of the biggest SNG providers in China. A total of 3919 valid responses and 541 valid responses were used to examine the continuance intention and the switching intention, respectively. SEM is utilized as the data analysis method. The proposed research models are supported by the empirical data. The continuance intention is determined by enjoyment, fantasy, escapism, social interaction, social presence, social influence, achievement and habit. The switching intention is determined by enjoyment, satisfaction, subjective norms, descriptive norms, alternative attractiveness, the need for variety, change experience, and adaptation cost. This study contributes to IS theories in three important ways. Firstly, it shows IS switching should be included in IS post-adoption research together with IS continuance. Secondly, a modern IS is usually multi-functional and SNG players have multiple reasons for using a SNG, thus a player’s beliefs about the hedonic, social and utilitarian perceptions of their continued use of the SNG exert significant effects on the continuance intention. Thirdly, the determinants of the switch ing intention mainly exert push, pull, and mooring effects. Players’ beliefs about their current SNG and the available alternatives, as well as their individual characteristics are all significant determinants of the switching intention. SNG players combine these effects in order to formulate the switching intention. Finally, this study presents limitations and suggestions for future research.

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Intracranial aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening condition requiring immediate neurocritical care. A ruptured aneurysm must be isolated from arterial circulation to prevent rebleeding. Open surgical clipping of the neck of the aneurysm or intra-arterial filling of the aneurysm sack with platinum coils are major treatment strategies in an acute phase. About 40% of the patients suffering from aSAH die within a year of the bleeding despite the intensive treatment. After aSAH, the patient may develop a serious complication called vasospasm. Major risk for the vasospasm takes place at days 5–14 after the primary bleeding. In vasospasm, cerebral arteries contract uncontrollably causing brain ischemia that may lead to death. Nimodipine (NDP) is used to treat of vasospasm and it is administrated intravenously or orally every four hours for 21 days. NDP treatment has been scientifically proven to improve patients’ clinical outcome. The therapeutic effect of L-type calcium channel blocker NDP is due to the ability to dilate cerebral arteries. In addition to vasodilatation, recent research has shown the pleiotropic effect of NDP such as inhibition of neuronal apoptosis and inhibition of microthrombi formation. Indeed, NDP inhibits cortical spreading ischemia. Knowledge of the pathophysiology of the vasospasm has evolved in recent years to a complex entity of early brain injury, secondary injuries and cortical spreading ischemia, instead of being pure intracranial vessel spasm. High NDP levels are beneficial since they protect neurons and inhibit the cortical spreading ischemia. One of the drawbacks of the intravenous or oral administration of NPD is systemic hypotension, which is harmful particularly when the brain is injured. Maximizing the beneficial effects and avoiding systemic hypotension of NDP, we developed a sustained release biodegradable NDP implant that was surgically positioned in the basal cistern of animal models (dog and pig). Higher concentrations were achieved locally and lower concentrations systemically. Using this treatment approach in humans, it may be possible to reduce incidence of harmful hypotension and potentiate beneficial effects of NDP on neurons. Intracellular calcium regulation has a pivotal role in brain plasticity. NDP blocks L-type calcium channels in neurons, substantially decreasing intracellular calcium levels. Thus, we were interested in how NDP affects brain plasticity and tested the hypothesis in a mouse model. We found that NDP activates Brain-derived neurotrophic factor (BDNF) receptor TrkB and its downstream signaling in a reminiscent of antidepressant drugs. In contrast to antidepressant drugs, NDP activates Akt, a major survival-promoting factor. Our group’s previous findings demonstrate that long-term antidepressant treatment reactivates developmental-type of plasticity mechanisms in the adult brain, which allows the remodeling of neuronal networks if combined with appropriate rehabilitation. It seems that NDP has antidepressant-like properties and it is able to induce neuronal plasticity. In general, drug induced neuronal plasticity has a huge potential in neurorehabilitation and more studies are warranted.

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Diplomityön tavoitteena on tutkia yrityskaupan vaikutuksia liiketoimintaan. Kuinka se muuttui yrityskaupan jälkeen ja kuinka se vastasi ennalta suunniteltua strategiaa. Työ tehtiin haastattelututkimuksena, jossa tutkittavina kohdeyhtiöinä oli kuusi yritystä, jotka olivat laajentuneet ostamalla yrityksen tai yrityksiä. Yhtiöiden tavoitteena oli hakea kasvua ostamalla valmis yritys tai liiketoiminta. Tutkimuksen teoreettisen viitekehityksen mukaisesti, jos yrityksen kasvustrategiana on kasvaa yrityskaupan avulla, sillä on vaikutus liiketoimintaan yrityskaupan jälkeen. Työn tuloksena saatiin arvio siitä, kuinka alkuperäinen strateginen tavoite saavutettiin ja mitä muita hyötyjä ja haittoja liiketoiminnan yhdistämisellä oli. Työn keskeisimmät tulokset olivat, että yrityskaupalla on aina vaikutus yrityksen liike- toimintaan. Paras hyöty saadaan, jos ostettavan yrityksen liiketointa on täydentävää, ei päällekkäistä liiketoimintaa. Yhdistymisestä saadaan hyötyjä jos yritykset voivat hyödyn- tää toinen toisensa osaamista. Etuina saadaan myös synergiahyötyjä, erityisesti yrityksen hallinnossa ja toiminnanohjausjärjestelmissä. Ostettavan yrityksen haltuunotto tulisi olla hallittu ja nopea.

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A regional geochemical reconnaissance by bottom stream sediment sampling, has delineated an area of high metal content in the north central sector of the North Creek Watershed. Development of a geochemical model, relating to the relative chemical concentrations derived from the chemical analyses of bottom sediments, suspended sediments, stream waters and well waters collected from the north central sector, was designed to discover the source of the anomaly. Samples of each type of material were analysed by the A.R.L. Direct Reading Multi-element Emission Spectrograph Q.A. 137 for elements: Na, K, Ca, Sr, Si, As, Pb, Zn, Cd, Ni, Ti, Ag, Mo, Be, Fe, AI, Mn, Cu, Cr, P and Y. Anomalous results led to the discovery of a spring, the waters of which carried high concentrations of Zn, Cd, Pb, As, Ni, Ti, Ag, Sr and Si. In addition, the spring waters had high concentrations of Na, Ca, Mg, 504 , alkalinity, N03' and low concentrations of K, Cl and NH3. Increased specific conductivity (up to 2500 ~mho/cm.) was noted in the spring waters as well as increased calculated total dissolved solids (up to 2047 mg/l) and increased ionic strength (up to 0.06). On the other hand, decreases were noted in water temperature (8°C), pH (pH 7.2) and Eh (+.154 volts). Piezometer nests were installed in the anomalous north central sector of the watershed. In accordance with the slope of the piezometric surface from wells cased down to the till/bedrock interface, groundwater flow is directed from the recharge area (northwest of the anomaly) towards the artesian spring via the highly fractured dolostone aquifer of the Upper Eramosa Member. The bedrock aquifer is confined by the overlying Halton till and the underlying Lower Eramosa Member (Vinemount Shale). The oxidation of sphalerite and galena and the dissolution of gypsum, celestite, calcite, and dolomite within the Eramosa Member, contributed its highly, dissolved constituents to the circulating groundwaters, the age of which is greater than 20 years as determined by tritium dating. Groundwater is assumed to flow along the Vinemount Shale and discharge as an artesian spring where the shale unit becomes discontinuous. The anomaly is located on a topographic low where bedrock is close to the surface. Thermodynamic evaluation of the major ion speciation from the anomalous spring and surface waters, showed gypsum to be supersaturated in these spring waters. Downstream from the spring, the loss of carbon dioxide from the spring waters resulted in the supersaturation with respect to calcite, aragonite, magnesite and dolomite. This corresponded with increases in Eh (+.304 volts) and pH (pH 8.5) in the anomalous surface waters. In conclusion, the interaction of groundwaters within the highly, mineralized carbonate source (Eramosa Member) resulted in the characteristic Ca*Mg*HC03*S04 spring water at the anomalous site, which appeared to be the principle effect upon controlling the anomalous surface water chemistry.

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Solid state nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for studying structural and dynamical properties of disordered and partially ordered materials, such as glasses, polymers, liquid crystals, and biological materials. In particular, twodimensional( 2D) NMR methods such as ^^C-^^C correlation spectroscopy under the magicangle- spinning (MAS) conditions have been used to measure structural constraints on the secondary structure of proteins and polypeptides. Amyloid fibrils implicated in a broad class of diseases such as Alzheimer's are known to contain a particular repeating structural motif, called a /5-sheet. However, the details of such structures are poorly understood, primarily because the structural constraints extracted from the 2D NMR data in the form of the so-called Ramachandran (backbone torsion) angle distributions, g{^,'4)), are strongly model-dependent. Inverse theory methods are used to extract Ramachandran angle distributions from a set of 2D MAS and constant-time double-quantum-filtered dipolar recoupling (CTDQFD) data. This is a vastly underdetermined problem, and the stability of the inverse mapping is problematic. Tikhonov regularization is a well-known method of improving the stability of the inverse; in this work it is extended to use a new regularization functional based on the Laplacian rather than on the norm of the function itself. In this way, one makes use of the inherently two-dimensional nature of the underlying Ramachandran maps. In addition, a modification of the existing numerical procedure is performed, as appropriate for an underdetermined inverse problem. Stability of the algorithm with respect to the signal-to-noise (S/N) ratio is examined using a simulated data set. The results show excellent convergence to the true angle distribution function g{(j),ii) for the S/N ratio above 100.