Thermotoga maritiman membraani-pyrofosfataasin A495K-mutantin ekspressio ja rakenteellinen karakterisointi

Membraani-pyrofosfataasit (M-PPaasit) katalysoivat pyrofosfaatin käänteisen hydrolyysin epäorgaanisiksi fosfaatti-ioneiksi. Tämä hydrolyysireaktio on kytkettynä protonien ja/tai natriumionien kuljetukseen solukalvon läpi luoden sähkökemiallisen gradientin, jota voidaan käyttää energialähteenä isäntäorganismin toimesta erilaisten stressiolosuhteiden aikana. M-PPaasien fysiologisesti merkittävät toiminnot maatalouden kannalta tärkeissä kasveissa sekä monissa ihmisten taudinaiheuttajissa, kuten Bacteroides fragilis, Plasmodium falciparum, Toxoplasma gondii ja Trypanosoma brucei, tekevät niistä tärkeän tutkimuskohteen. Lukuisiin M-PPaaseihin kohdistuneista biokemiallisista tutkimuksista sekä Thermotoga maritima ja Vigna radiata M-PPaasien rakenteiden karakterisoinneista riippumatta, M-PPaasien biokemiasta sekä katalyyttisestä mekanismista on edelleen avoimia kysymyksiä, joista yksi on K+-ioniriippuvuus. Mutaatiotutkimukset ovat viitanneet siihen, että yksi aminohappotähde paikassa 495 on ainoa K+-ioniriippuvuutta määrittelevä tekijä M- PPaaseissa. K+-riippuvaisissa M-PPaaseissa tämä aminohappotähde on alaniini ja sen läheisyyteen sitoutuneella K+-ionilla on todettu olevan tehostava vaikutus K+-riippuvaisissa M-PPaaseissa. Sen on osoitettu kasvattavan pyrofosfaatin hydrolyysireaktion maksimaalista nopeutta. K+-riippumattomissa M-PPaaseissa, paikassa 495 sijaitsee lysiini aminohappotähde, jonka ε-NH3+-ryhmän on rakenteellisten mallinnusten sekä AlaàLys (A495K) mutaatiotutkimusten perusteella ehdotettu jäljittelevän rakenteellisesti ja toiminnallisesti K+ ionin aktivoivaa vaikutusta K+-riippuvaisissa M- PPaaseissa. Antaakseen rakenteellista perustetta tälle väitteelle, tässä tutkimuksessa hypertermofiilisen syvänmeren bakteerin T. maritima M-PPaasi, joka sisältää yhden A495K pistemutaation, tuotettiin Saccharomyces cerevisiae:ssa, liuotettiin korkean lämpötilan (“Hot-solve”) menetelmällä, puhdistettiin metalli affiniteetti kromatografialla ja rakenteellisesti karakterisoitiin röntgenkristallografialla. Niin kuin on ehdotettu, lisätyn lysiinin ε-NH3+-ryhmä todettiin asettuvan samaan kohtaan ja muodostavan samat vuorovaikutukset aktiivisessa keskuksessa kuin K+-ioni K+- riippuvaisissa M-PPaaseissa. Tästä huolimatta nämä rakenteelliset löydökset ovat ristiriidassa tehdyn hydrolyyttisen aktivisuusanalyysin kanssa, josta ilmeni A495K mutaation, K+-riippuvuuden hävittämisen lisäksi, vähentävän kokonaisaktiivisuutta K+ konsentraatiosta riippuen ~2-10-kertaisesti villityyppiin verrattuna. Nämä löydökset viittaavat siihen, että on olemassa jokin muu tekijä (tai muita tekijöitä), 495 aminohappotähteen lisäksi, joka määrittelee K+-ioniriippuvuuden M-PPaaseissa.Membrane-bound pyrophosphatases (M-PPases) catalyse the reversible hydrolysis of pyrophosphate into two inorganic phosphate molecules. This hydrolysis is coupled to the transport of protons and/or sodium ions across the biological membrane, generating an electrochemical gradient, which can be utilized by the host organism as an energy source under different stress conditions. The essential physiological roles of M-PPases in agriculturally relevant plants and various human pathogens, such as Bacteroides fragilis, Plasmodium falciparum, Toxoplasma gondii, and Trypanosoma brucei, make them an important research area. Despite the biochemical studies conducted with several M-PPases and structural characterization of Thermotoga maritima and Vigna radiata M-PPases, there remain several questions regarding the biochemistry and catalytic mechanism of M-PPases, one being the basis of K+ dependence. Mutational studies have suggested that a single residue at position 495 is the sole determinant of K+ dependence in M-PPases. In K+-dependent M-PPases this residue is an alanine and a K+ ion binding in close proximity of it, has been shown of having stimulatory effect on K+- dependent M-PPases by increasing the maximal rate of pyrophosphate hydrolysis. In K+-independent M-PPases, a lysine residue resides at 495 position, where the ε-NH3+ group of the lysine residue has been suggested, based on structural modelling and AlaàLys (A495K) mutational studies, to structurally and functionally mimic the activating function of K+ in K+-dependent M-PPases. In order to provide structural basis to this, in this study, a M-PPase belonging to a hyperthermophilic deep- sea bacterium T. maritima containing a single A495K point mutation was expressed in Saccharomyces cerevisiae, solubilized using the high-temperature (“Hot-solve”) method, purified with metal affinity chromatography and structurally characterized using X-ray crystallography. As suggested, the ε-NH3+ group of the introduced lysine was shown to occupy the same space and form the same interactions at the active site as the K+ ion in K+-dependent M-PPases. However, these structural findings were in contradiction with the conducted hydrolytic activity assay which showed that the A495K mutation, besides abolishing K+ dependence, significantly reduced the overall activity compared to the wild type by ~2-10-fold, depending on the K+ concentration. These findings suggest that additional factor(s) besides the 495 residue determine the K+ dependence in M-PPases

Is land surface temperature an earthquake precursor?

Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial TechnologiesThis study aims to investigate and explain the land surface temperature variations before and after the earthquake of August 11, 2012 that struck Iran, by making critical considerations of weather factors. This goal underlies two main objectives. The first objective was to detect land surface temperature anomalies over time in respect to the day of the earthquake, and over space relative to the location of the earthquake epicentre. The other main objective was to determine whether the detected anomalies originated from the weather, or the earthquake. To meet these objectives, observations of remote sensing land surface temperature, near-ground air temperature and air temperature of multiple atmospheric levels were used. All the datasets were daily night-time observations extending to a period of five years, repeatedly from July 11, to August 31. All the observations of the three datasets were visualized in space and time to seek anomalous temperature patterns. The results showed several prominent land surface temperature increases over the 5-year period, but none of them fell out a few days before the earthquake. The most enduring land surface temperature increase occurred two days after the earthquake. In contrast to the land surface temperature, air temperature exhibited the sharpest anomalies of the entire period a few days before the earthquake. Both the air and the land surface temperature increased periodically few times within the 5-year period. The high temperature patterns that were detected in the near-ground air also matched in time with the patterns found in the temperature of multiple atmospheric levels. All three approaches undertaken in this study were consistent with each-other in terms of results. Based on those results, it was concluded that there were no land surface temperature anomalies in the expected few days before the earthquake. All the detected temperature increases were indeed seasonal patterns repeating roughly in the same period of the year, and in the same spatial extent and intensity. These warm patterns were due to normal weather cycles. The sharp air temperature anomalies detected in the few days preceding the earthquake may suggest that the focus, if thermal precursors exist at all, should indeed be set on the air temperature instead of land surface temperature

Diversity on boards of directors: evidence from Portuguese and Spanish non-financial companies

The main purpose of this work project is to investigate whether attributes of board of directors such as gender, board’s size, type auditor hired, proportion of foreign directors and outside directors influence company performance. A hierarchical ordinary least square regression is performed using data from 83 non-financial companies listed on the Portuguese and Spanish stock exchange. The conclusions indicate that board size and proportion of foreign directors are positively related to company turnover. Concerning the control variables used, company size is positively related to company performance. To sum up, the empirical results suggest that board attributes positively influence company performance

Enhancing Situational Awareness for Rotorcraft Pilots Using Virtual and Augmented Reality

Rotorcraft pilots often face the challenge of processing a multitude of data, integrating it with prior experience and making informed decisions in complex, rapidly changing multisensory environments. Virtual Reality (VR), and more recently Augmented Reality (AR) technologies have been applied for providing users with immersive, interactive and navigable experiences. The research work described in this thesis demonstrates that VR/AR are particularly effective in providing real-time information without detracting from the pilot\u27s mission in both civilian and military engagements. The immersion of the pilot inside of the VR model provides enhanced realism. Interaction with the VR environment allows pilots to practice appropriately responding to simulated threats. Navigation allows the VR environment to change with varying parameters. In this thesis, VR/AR environments are applied for the design and development of a head-up display (HUD) for helicopter pilots. The usability of the HUD that is developed as a part of this thesis is assessed using established frameworks for human systems engineering by incorporating best practices for user-centered design. The research work described in this thesis will demonstrate that VR/AR environments can provide flexible, ergonomic, and user-focused interfaces for real-time operations in complex, multisensory environments

Lattice relaxation in solid solutions: long-range vs. short-range structure around Cr3+ and Co2+ in oxides and silicates

This dissertation reports the results derived from the 3-year doctoral thesis project aimed at exploring some oxide and silicate structures as promising ceramic pigments with enhanced colorimetric properties with respect to the traditional colorants. Solid solutions of perovskite, alumoniobite, and melilite compounds were obtained by doping octahedral and tetrahedral coordination sites with transition metal ions (e.g. Cr3+, Co2+, and Zn2) through a solid-state synthesis performed by means of an industrial-like process. The analytical techniques adopted to investigate the synthesized compounds allowed the determination of the "averaged" crystal structure, or the so termed long-range properties, and the short-range properties (i.e. the local structure around the substituting ions) through X-ray powder diffraction and electron absorption spectroscopy (EAS), respectively. As stated by Geiger (2001) "an understanding of the microscopic, mesoscopic and macroscopic properties and of the behaviour of solid solutions under different conditions is a challenge for all disciplines concerned with the solid state". As a matter of fact, the precise determination of a structure around impurities results fundamental to provide detailed information on their incorporation and on physical properties. For instance, in the case of the solid solutions here reported, the lattice incorporation of transition metal ions as impurities is the cause of their gradual coloration. Most of the times, such a coloration is more intense as greater is the impurity amount. The final goal of this work, was attained by calculating the structural relaxation coefficient for each studied solid solution by combining the mean with the local bond distances achieved by XRPD and EAS, respectively

Els moriscos valencians : una panoràmica historiogràfica

L'article traça una panoràmica historiogràfica de l'expulsió dels moriscos i les seves conseqüències al País Valencià. Primerament analitza l'obra dels contemporanis de l'expulsió i posteriorment passa a estudiar la percepció d'injustícia de les condicions establertes a les cartes de població, especialment durant la Segona Germania de 1693, els plets antisenyorials del segle xviii i l'actuació dels diputats valencians en la discussió del decret d'abolició de les senyories en les corts de Cadis. Després tracta el gir de la historiografia liberal decimonònica i l'obra dels historiadors conservadors. Durant la primera meitat del segle xx es va produir un buit historiogràfic, trencat amb l'obra dels deixebles de Fernand Braudel, especialment Halperín Donghi, i la important aportació de Joan Reglà. La tesi d'Eugeni Císcar significà un punt d'inflexió en la historiografia sobre els moriscos i va iniciar un interessant debat sobre la societat morisca i les conseqüències del seu foragitament, que va promoure les investigacions i la reflexió teòrica sobre el tema. En els nostres dies aquesta problemàtica es coneix molt millor que fa cinquanta anys, però així i tot queden punts obscurs que tan sols futurs treballs aclariran.El artículo traza una panorámica historiográfica de la expulsión de los moriscos y sus consecuencias en el País Valenciano. Primero analiza la obra de los contemporáneos de la expulsión y posteriormente pasa a estudiar la percepción de injusticia de las condiciones establecidas en las cartas de población, especialmente durante la Segunda Germanía de 1693, los pleitos antiseñoriales del siglo XVIII y la actuación de los diputados valencianos en la discusión del decreto de abolición de los señoríos en las cortes de Cádiz. Después trata el giro de la historiografía liberal decimonónica y la obra de los historiadores conservadores. Durante la primera mitad del siglo XX se produjo un vacío historiográfico, roto con la obra de los discípulos de Fernand Braudel, especialmente Halperín Donghi, y la importante aportación de Joan Reglà. La tesis de Eugenio Císcar significó un punto de inflexión en la historiografía sobre los moriscos e inició un interesante debate sobre la sociedad morisca y las consecuencias de su expulsión, que promovió las investigaciones y la reflexión teórica sobre el tema. En nuestros días esta problemática se conoce mucho mejor que hace cincuenta años, pero, con todo, quedan puntos oscuros que sólo futuros trabajos aclararán.The article traces a panoramic view of the historiography about the expulsion of the Moriscos and its consequences in the Valencia. It analyzes first the work of the contemporaries and then proceeds to the study of the perception of injustice in the conditions instituted in the resettlement charts, mainly during the Second Germania of 1693, the lawsuits against the landlords during the 18th century and the behaviour of the Valencian deputies in the discussion of the decree of abolition of the feudal regime in the Cortes of Cadiz. It goes over then with the historiographic turn of the liberal historians and also the work of the conservative ones. In the first half of the 20th century there was an emptiness of studies, only broken with the work of the disciples of Fernand Braudel, mainly Halperín Donghi, and the important research made by Joan Reglà. The work of Eugeni Císcar meant a turning point in the historiography about the Moriscos and began an interesting debate about the Morisco society and the consequences of the expulsion. Nowadays these facts are better known than fifty years earlier, but nonetheless there remain dark questions that only future researches will make clear

El ducat de Gandia en el mapa senyorial valencià (cap a 1540): una primera aproximació

Català: Reconstrucció del mapa de les senyories valencianes en temps del duc de Gandia Francesc de Borja (mitjan segle XVI). El nucli del treball, el constitueixen disset mapes i dos quadres de superfície i població, confeccionats a partir de cròniques coetànies, del cens de 1609 i de la historiografia local més solvent. Paraules clau: Cartografia; Noblesa valenciana s. XVI. Castellano: Reconstrucción del mapa señorial valenciano en tiempos del duque de Gandía Francisco de Borja (mediados del siglo XVI). Constituyen el centro del trabajo diecisiete mapas y dos cuadros de superficie y población, realizados a partir de crónicas coetáneas, el censo de 1609 y la historiografía local más solvente. Palabras clave: Cartografía; Nobleza valenciana s. XVI

L'Expulsió dels moriscos als Països Catalans: ideologia i història

L'expulsió dels moriscos als Països Catalans, i especialment al País Valencià, ha estat objecte d'interpretacions diverses. Sobretot els historiadors que s'han ocupat del tema han oscil·lat entre una postura que podem anomenar moriscòfila i una altra moriscòfoba. Els primers han estimat que l'expulsió de la minoria islàmica va privar el país d'una població econòmicament molt activa i que per tant aquell fet històric va suposar un greu entrebanc en el procés de desenvolupament capitalista. Els segons, en canvi, tot suposant que els moriscos no eren una minoria econòmica tan decisiva, han pensat que la seva expulsió no tingué gaire influència en aquest sentit i, fins i tot que, si la va tenir, fou en el sentit contrari. Ambdues interpretacions han estat fortament carregades de pressupòsits ideològics. Aquest article pretèn fer una anàlisi de la qüestió de forma més objectiva, analitzant els canvis en l'estructura del poblament després de l'expulsió, l'evolució de la producció agrària durant tota l'edat moderna i, finalment, els canvis en l'estructura de la propietat. Els seus resultats semblen avalar la interpretació que hem quedat en anomenar moriscòfoba, ja que l'estructura del poblament, l'evolució de la producció agrària i els canvis en l'estructura de la propietat semblen assenyalar una acceleració del creixement econòmic capitalista després de l'expulsió dels moriscos