3,733 research outputs found

    Distribution of the Object Oriented Databases. A Viewpoint of the MVDB Model's Methodology and Architecture

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    In databases, much work has been done towards extending models with advanced tools such as view technology, schema evolution support, multiple classification, role modeling and viewpoints. Over the past years, most of the research dealing with the object multiple representation and evolution has proposed to enrich the monolithic vision of the classical object approach in which an object belongs to one hierarchy class. In particular, the integration of the viewpoint mechanism to the conventional object-oriented data model gives it flexibility and allows one to improve the modeling power of objects. The viewpoint paradigm refers to the multiple descriptions, the distribution, and the evolution of object. Also, it can be an undeniable contribution for a distributed design of complex databases. The motivation of this paper is to define an object data model integrating viewpoints in databases and to present a federated database architecture integrating multiple viewpoint sources following a local-as-extended-view data integration approach.object-oriented data model, OQL language, LAEV data integration approach, MVDB model, federated databases, Local-As-View Strategy.

    Unbiased bases (Hadamards) for 6-level systems: Four ways from Fourier

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    In quantum mechanics some properties are maximally incompatible, such as the position and momentum of a particle or the vertical and horizontal projections of a 2-level spin. Given any definite state of one property the other property is completely random, or unbiased. For N-level systems, the 6-level ones are the smallest for which a tomographically efficient set of N+1 mutually unbiased bases (MUBs) has not been found. To facilitate the search, we numerically extend the classification of unbiased bases, or Hadamards, by incrementally adjusting relative phases in a standard basis. We consider the non-unitarity caused by small adjustments with a second order Taylor expansion, and choose incremental steps within the 4-dimensional nullspace of the curvature. In this way we prescribe a numerical integration of a 4-parameter set of Hadamards of order 6.Comment: 5 pages, 2 figure

    Single spin measurement using spin-orbital entanglement

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    Single spin measurement represents a major challenge for spin-based quantum computation. In this article we propose a new method for measuring the spin of a single electron confined in a quantum dot (QD). Our strategy is based on entangling (using unitary gates) the spin and orbital degrees of freedom. An {\em orbital qubit}, defined by a second, empty QD, is used as an ancilla and is prepared in a known initial state. Measuring the orbital qubit will reveal the state of the (unknown) initial spin qubit, hence reducing the problem to the easier task of single charge measurement. Since spin-charge conversion is done with unit probability, single-shot measurement of an electronic spin can be, in principle, achieved. We evaluate the robustness of our method against various sources of error and discuss briefly possible implementations.Comment: RevTeX4, 4 pages, some figs; updated to the published versio

    Time-space evolution and volcanological features of the Late Miocene-Quaternary Calimani-Gurghiu-Harghita Volcanic Range, East Carpathians, Romania. A Review.

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    The Carpathian-Pannonian Region (CPR) hosts one of the major Cainozoic volcanic provinces of Europe extending in space over 6 eastern European countries.The lithospheric evolution of this large area governed by large-scale asthenospheric processes is recorded by products of volcanic activity occurred during a time interval of more than 21 million years. According to their surface occurrence areas, ages and composition the Neogene volcanics of CPR were systematized in three main groups: 1) mostly explosive products of felsic magmas generated at the beginning of volcanism in the whole CPR and in their particular occurrence areas (21-12 Ma) developed in the actual intra-Carpathian Pannonian Basin, 2) mostly intermediate calc-alkaline rocks emplaced in both the intra-Carpathian areas and along the arcuate Carpathian fold-and-thrust belt, and 3) Na- and K- alkaline and ultra-alkaline products clustered in a number of monogenetic volcanic fields across the whole intra-Carpathian realm developed in the final stages of volcanic activity of the CPR as a whole and of their particular occurrence areas. The ca. 160 km long Călimani-Gurghiu-Harghita volcanic range (CGH) developed as part of the intermediate calc-alkaline volcanism closely related in space with the fold-and-thrust belt of the Carpathians, representing the south-eastern segment of the CPR. Although its map view and general petrochemical and volcanological characteristics are quite similar with those of other segments of the orogene belt- tied calc-alkaline volcanic segments, at a closer look CGH displays a number of unique features. The time-space evolution of CGH is particular not only in that it is the youngest (10.5 to < 0.05 Ma) dominantly calc-alkaline segment in CPR but also it shows a transient character. Unlike other segments along which volcanism occurred simultaneously forming true subduction-related 400 to 800 km long volcanic fronts which were stable in time for millions of year, in CGH volcanic activity migrated continuously along the range from NW to SE. So, during any given 1 Ma time interval active volcanism was restricted to very limited areas and to just a few active volcanic centers. The along-range shift of volcanic foci was concurrent with progressively lower volumes of magma erupted and decreasing magma output rates. As a result, gradually lower-volume and less complex volcanic edifices were built up. Moreover, at the range-ending and youngest South Harghita sub-segment, magma compositions gradually changed from normal calc-alkaline to high-K calc-alkaline and shoshonitic, and adakitic features emerged at the end of volcanic activity, after a time gap of 0.5 Ma. This marks a major geodynamic event in the development of the East Carpathians themselves. During the transient volcanism of CGH, edifices of varying volume and complexity were built up forming a row of tightly- packed adjoining stratovolcanoes/composite volcanoes whose peripheral volcaniclastic aprons complexly juxtaposed, overlapped and merged with each other. The largest ones (Călimani caldera, and Fâncel-Lăpuşna) developed until caldera stage. Some of them (Rusca-Tihu in the Călimani Mts., Vârghiş in the North Harghita Mts.) became unstable during their growth and collapsed, generating widespread large-volume debris avalanche deposits. Edifice instability was solved by volcano-basement interaction processes, such as volcano spreading, at some large-volume volcanoes (in particular those in the Gurghiu Mts.). Volcano typology changed at the smaller-volume constructs toward the southeastern terminus of the range in the South Harghita Mts. from typical large stratovolcanoes to smaller composite volcanoes, dome clusters and isolated domes and simpler internal structures. As a whole, CGH displays an extremely particular evolutionary pattern strongly suggesting a transient character and decreasing to extinguishing volcanic activity along its length from NW to SE

    Computer aided modeling of the quadrilateral mechanism

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    Energy levels and decoherence properties of single electron and nuclear spins in a defect center in diamond

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    The coherent behavior of the single electron and single nuclear spins of a defect center in diamond and a 13C nucleus in its vicinity, respectively, are investigated. The energy levels associated with the hyperfine coupling of the electron spin of the defect center to the 13C nuclear spin are analyzed. Methods of magnetic resonance together with optical readout of single defect centers have been applied in order to observe the coherent dynamics of the electron and nuclear spins. Long coherence times, in the order of microseconds for electron spins and tens of microseconds for nuclear spins, recommend the studied system as a good experimental approach for implementing a 2-qubit gate.Comment: 4 pages, 4 figure

    Treatment of anaerobic infection after caesarean section (case report)

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    Catedra chirurgie generală, USMF “Nicolae Testemiţanu”, Spitalul Clinic Municipal nr.1, Chişinău, Republica Moldova, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Femeile care au suportat operaţia cezariană prezintă un risc de la 5 la 20 ori mai mare pentru complicaţii infecţioase, faţă de cele care nasc pe cale naturală. Complicaţiile includ endometritele (20-85% din cazuri), infecţia plăgii (25%), bacteriemia, abcesele pelviene, şocul septic, fasciitele necrotizante şi tromboflebitele venelor pelviene. Principalele microorganisme responsabile pentru endometrite sunt bacilii aerobi gram-negativi (E.coli); bacilii anaerobi gram-negativi (Bacteroides sp. şi Gardnerella vaginalis); cocii aerobi gram-pozitivi (streptococii din Grupul B şi Grupul D); şi cocii anaerobi gram-pozitivi (Peptococcus sp. şi Peptostreptococcus sp). Pe parcursul travaliului şi a naşterii abdominale endometriumul şi cavitatea peritoneală sunt invariabil contaminate cu un număr mare de bacterii patogene aerobe şi anaerobe care prolifere ază în lichidul peritoneal postoperator sero-sangvin. Caz clinic: Este raportat cazul unei femei obeze (IMC=40) cu vârsta de 39 ani, care a fost supusă operaţiei cezariene la a 13-a naştere. În pofida indicaţiilor nu au fost administrate antibiotice în scop profilactic nici până, nici după intervenţie. Peste 2 zile bolnava a fost transferată în secţia de chirurgie datorită dehiscenţei şi infecţiei plăgii. S-a recurs la histerectomie totală. Analiza bacteriologică a pus în evidenţă prezenţa Enterobacter aerogenus, Enterococcus sp. şi a Staphylococcus aureus. Pe parcursul a 28 de zile au fost administrate antibiotice în conformitate cu sensibilitatea patogenilor, concomitent cu tratamentul local al plăgii. Vindecarea completa a fost atestată în ziua a 56-a. Concluzie: În grupul de risc este strict indicată antibiotico-profilaxia peri-cezariană.Introduction: Women who undergo caesarean section have a 5 to 20-fold greater risk of infectious complications than those after normal vaginal delivery. The complications include endometritis (20-85% of cases), wound infection (25%), bacteremia, pelvic abscess, septic shock, necrotizing fasciitis, and septic pelvic vein thrombophlebitis. The main microorganisms responsible for endometritis are aerobic gram-negative bacilli (E.coli); anaerobic gram-negative bacilli (Bacteroides sp. and Gardnerella vaginalis); aerobic gram-positive cocci (Group B and Group D streptococci); and anaerobic gram-positive cocci (Peptococcus sp. and Peptostreptococcus sp). During labor and abdominal delivery, the endometrium and peritoneal cavity invariably are contaminated with large numbers of highly pathogenic aerobic and anaerobic bacteria which are proliferating in the serosanguineous postoperative peritoneal fluid. Clinical case: We report a case of an obese (BMI=40) 39 years old woman who suffered a caesarean section at 13th delivery. In spite of indications, no prophylactic antibiotics where administrated nor before neither after intervention. After 2 days she was transferred to the Surgical Department due to wound dehiscence and infection. Total hysterectomy was performed. Bacteriological analysis identified presence of Enterobacter aerogenus, Enterococcus sp. and Staphylococcus aureus. There were administrated antibiotics according to sensibility of the pathogens for 28 days, along with local debridement of the wound. After 56 days of hospitalization complete healing was reported. Conclusion: It is strictly indicated to use prophylactic antibiotic administration peri-caesarean section in the risk group

    Heterocyst placement strategies to maximize growth of cyanobacterial filaments

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    Under conditions of limited fixed-nitrogen, some filamentous cyanobacteria develop a regular pattern of heterocyst cells that fix nitrogen for the remaining vegetative cells. We examine three different heterocyst placement strategies by quantitatively modelling filament growth while varying both external fixed-nitrogen and leakage from the filament. We find that there is an optimum heterocyst frequency which maximizes the growth rate of the filament; the optimum frequency decreases as the external fixed-nitrogen concentration increases but increases as the leakage increases. In the presence of leakage, filaments implementing a local heterocyst placement strategy grow significantly faster than filaments implementing random heterocyst placement strategies. With no extracellular fixed-nitrogen, consistent with recent experimental studies of Anabaena sp. PCC 7120, the modelled heterocyst spacing distribution using our local heterocyst placement strategy is qualitatively similar to experimentally observed patterns. As external fixed-nitrogen is increased, the spacing distribution for our local placement strategy retains the same shape while the average spacing between heterocysts continuously increases.Comment: This is an author-created, un-copyedited version of an article accepted for publication in Physical Biology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher-authenticated version will be available onlin
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