A Note on Doubly Warped Product Contact CR-Submanifolds in trans-Sasakian Manifolds

Warped product CR-submanifolds in Kaehlerian manifolds were intensively studied only since 2001 after the impulse given by B.Y. Chen. Immediately after, another line of research, similar to that concerning Sasakian geometry as the odd dimensional version of Kaehlerian geometry, was developed, namely warped product contact CR-submanifolds in Sasakian manifolds. In this note we proved that there exists no proper doubly warped product contact CR-submanifolds in trans-Sasakian manifolds.Comment: 5 Latex page

Ti-Zr-Si-Nb nanocrystalline alloys and metallic glasses: Assessment on the structure, thermal stability, corrosion and mechanical properties

The development of novel Ti-based amorphous or \u3b2-phase nanostructured metallic materials could have significant benefits for implant applications, due to improved corrosion and mechanical characteristics (lower Young's modulus, better wear performance, improved fracture toughness) in comparison to the standardized \u3b1+\u3b2 titanium alloys. Moreover, the devitrification phenomenon, occurring during heating, could contribute to lower input power during additive manufacturing technologies. Ti-based alloy ribbons were obtained by melt-spinning, considering the ultra-fast cooling rates this method can provide. The titanium alloys contain in various proportions Zr, Nb, and Si (Ti60Zr10Si15Nb15, Ti64Zr10Si15Nb11, Ti56Zr10Si15Nb19) in various proportions. These elements were chosen due to their reported biological safety, as in the case of Zr and Nb, and the metallic glass-forming ability and biocompatibility of Si. The morphology and chemical composition were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy, while the structural features (crystallinity, phase attribution after devitrification (after heat treatment)) were assessed by X-ray diffraction. Some of the mechanical properties (hardness, Young's modulus) were assessed by instrumented indentation. The thermal stability and crystallization temperatures were measured by differential thermal analysis. High-intensity exothermal peaks were observed during heating of melt-spun ribbons. The corrosion behavior was assessed by electrocorrosion tests. The results show the potential of these alloys to be used as materials for biomedical applications

Evaluation Model of the Entrepreneurial Character in EU Countries.

Abstract The evidence of entrepreneurship development as a factor of sustainable growth at national and regional level frequently calls for the interest of theorists and practitioners on identifying and outlining the best conditions and economic essential prerequisites for supporting the entrepreneurial initiatives on the long term. In this context, the objective of the present research is to analyse and measure the entrepreneurial character of the European Union member countries in an integrated manner, by developing an innovative model for proposing specific action lines and objectively evaluating the entrepreneurship development in the investigated states. Our model is based on a synthesis variable of the entrepreneurial national character, which was developed by sequential application of principal component analysis, while the initial variables are from secondary sources with good conceptual representativeness. Depending on the objective relevance of the three model components (cultural, economic and administrative, and entrepreneurial education components), the achieved results confirm the importance of a favourable cultural and economic and administrative background for entrepreneurship development and they reiterate the inefficiency of isolated entrepreneurial education unless supported by good entrepreneurial culture or adequate economic and administrative infrastructure. The case of Romania, in relation with the European Union member countries, is presented in detail

Giant retroperitoneal schwannoma

Spit. CF 2, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011OBIECTIVUL STUDIULUI: Se prezintă cazul unei tumori retroperitoneale de schwannom gigant. Schwannoamele sunt tumori neurogene, non epiteliale ce se dezvoltă din tecile nervilor periferici (redenumite recent-PNST). Localizarea retroperitoneală a acestor tumori este foarte rar intalnită în practica clinică (0,3-0,5 %). Lucrarea prezintă cazul unui bolnavi în varsta de 52 de ani, de profesie inginer, fără alte antecedente patologice sau formațiuni tegumentare de neurofibromatoza care a fost spitalizat pentru dureri abdominale, marirea de volum a abdomenului și creșterea cu 9 kg. Explorările imagistice și biologice care arată o tumoră retroperitoneală gigantă, banuita benignă, nu au putut preciza originea tumorii. Se practică laparotomie mediană xifo-pubiană cu abord transperitoneal. Intraoperator se constată o tumoră retroperitoneală gigantă de aspect lipomatos. S-a efectuat ablația completă a tumorii fără sacrificii de organe. Dimensiunile foarte mari ale tumorii, greutatea de 8000 gr. și aspectul macroscopic sugerează benignitatea. Examenul histopatologic al tumorii este de schwannom benign, confirmat și de examenul imunohistochimic. Evoluție favorabilă în 14 zile postoperator. CONCLUZII: Spațiul retroperitoneal este foarte generos pentru dezvoltarea unor mase tumorale foarte mari. Incidența schwannoamelor este foarte mică. Prezentarea clinică a acestor tumori este nespecifică, cu dificultați de diagnostic preoperator. Absența invaziei capsulare și a metastazelor, confirmă natura benignă a acestor tumori.THE OBJECTIVE OF THE STUDY: Case report of the tumor retroperitoneal of the giant schwannoma. The schwannomas are neorogenic tumors non epithelial which develope of the peripheral nerve sheats. (renamed recently-PNST). Retroperitoneal localization of this tumor is low in clinical practice (0,3-0,5%). Case report-an 52-year- old male patient, by engineer profession, without pathological records and without neurofibromatosis type tegumentary lisions, was hospitalized for abdominal pains, a change of the aspect of the abdomen and taken in weight 9 kilograms. Imaging and biologic tests wich establish a giant retroperitoneal tumor, possibly benign, couldn’t define the exact origin. In xifo-pubian laparotomy and transperitoneal abord we found a giant retroperitoneal tumor of fatty aspect. Tumor excision was performed without viscus sacrifice. The very big size of the tumor, weight-8000gr., the macroscopic aspect suggests benign tumor. Histological examination of neurogenic tumor showed a benign schwannoma, confirmed also of the immunohistochemical test. Postoperative course was favorable in 14 days. CONCLUSIONS: The retroperitoneal space is greatly for the growth of the big tumors. The incidence of the schwannomas is low. The clinical presentation of these tumors is non specific, with difficulties for the correct diagnosis in preoperative period. The absence of the capsule invasion and of the metastasis confirm benign origin of these tumors

Charged exctions in the fractional quantum Hall regime

We study the photoluminescence spectrum of a low density ($\nu <1$) two-dimensional electron gas at high magnetic fields and low temperatures. We find that the spectrum in the fractional quantum Hall regime can be understood in terms of singlet and triplet charged-excitons. We show that these spectral lines are sensitive probes for the electrons compressibility. We identify the dark triplet charged-exciton and show that it is visible at the spectrum at $T<2$ K. We find that its binding energy scales like $e^{2}/l$, where $l$ is the magnetic length, and it crosses the singlet slightly above 15 T.Comment: 10 pages, 5 figure

Control and Supervision of Wind Energy Conversion Systems

This paper is about a PhD thesis and includes the study and analysis of the performance of an onshore wind energy conversion system. First, mathematical models of a variable speed wind turbine with pitch control are studied, followed by the study of different controller types such as integer-order controllers, fractional-order controllers, fuzzy logic controllers, adaptive controllers and predictive controllers and the study of a supervisor based on finite state machines is also studied. The controllers are included in the lower level of a hierarchical structure composed by two levels whose objective is to control the electric output power around the rated power. The supervisor included at the higher level is based on finite state machines whose objective is to analyze the operational states according to the wind speed. The studied mathematical models are integrated into computer simulations for the wind energy conversion system and the obtained numerical results allow for the performance assessment of the system connected to the electric grid. The wind energy conversion system is composed by a variable speed wind turbine, a mechanical transmission system described by a two mass drive train, a gearbox, a doubly fed induction generator rotor and by a two level converter

Mediastinal cavernous hemangioma in a child with pulmonary hypertension

Department of Radiology, State University of Medicine and Pharmacy Republic of Moldova, Moldova, Department of Cardiac Surgery, Clinical Republican Hospital, State University of Medicine and Pharmacy Republic of Moldova, Moldova, Department of Pathology, Clinical Republican Hospital, State University of Medicine and Pharmacy Republic of Moldova, MoldovaAbstract We present a rare case of mediastinal cavernous hemangioma in a 9-year old girl with advanced pulmonary hypertension. Dynamic contrast enhanced computed tomography of the chest revealed a heterogeneous mass in the antero-superior mediastinum with multiple scattered calcifications, gradually increasing puddles of contrast enhancement and a dilated central vein draining into the superior venae cavae. Surgical resection was performed via median sternotomy. The central vein was ligated in close proximity to its draining point and the entire mass was carefully dissected and excised. The histopathological findings were consistent with cavernous hemangioma. Her postoperative course was uneventful and she was subsequently discharged. The cause of her pulmonary hypertension, however, remained uncertain and required further investigation

Unusual aggressive and rapidly growing glioblastoma multiforme: Case presentation

Glioblastoma multiform is one of the most rapidly progressing cerebral tumors and the most aggressive one in our neurosurgical experience. We present the case of a 45 year old patient with very aggressive type of tumor who had come to our service for the following: intense headache, confusion, right hemiparesis installed approximately one month before. IRM scan shows up the presence of a large tumoral mass without a precise border in the left temporal-parietal region which had extended all the way down to the thalamus. The planned intervention used 5-aminolevulinic acid (5-ALA) for the precise removal of the tumor mass, suboptimal because of the risk of lesioning the motor tracts – indicated by the intraoperative electrophysiological monitoring. After surgery the outcome was good with the partial regression of the motor deficit, but only after 3 weeks due to the unexpected tumor growth the neurological status started to decay and even worsened. The patient underwent surgery again with the partial remission of the symptoms although following imagistic controls showed up fast tumor growth once more. He was recommended to oncology service for the beginning of radiotherapy. We consider the evolution and invasion of this tumor in only a 3 weeks period being impressive

On the k-Symplectic, k-Cosymplectic and Multisymplectic Formalisms of Classical Field Theories

The objective of this work is twofold: First, we analyze the relation between the k-cosymplectic and the k-symplectic Hamiltonian and Lagrangian formalisms in classical field theories. In particular, we prove the equivalence between k-symplectic field theories and the so-called autonomous k-cosymplectic field theories, extending in this way the description of the symplectic formalism of autonomous systems as a particular case of the cosymplectic formalism in non-autonomous mechanics. Furthermore, we clarify some aspects of the geometric character of the solutions to the Hamilton-de Donder-Weyl and the Euler-Lagrange equations in these formalisms. Second, we study the equivalence between k-cosymplectic and a particular kind of multisymplectic Hamiltonian and Lagrangian field theories (those where the configuration bundle of the theory is trivial).Comment: 25 page

Tidal tensors in the description of gravity and electromagnetism

In 2008-2009, F. Costa and C. Herdeiro proposed a new gravito-electromagnetic analogy, based on tidal tensors. We show that connections on the tangent bundle of the space-time manifold can help not only in finding a covnenient geometrization of their ideas, but also a common mathematical description of the main equations of gravity and electromagnetism.Comment: submitted to: Journal of Nonlinear Mathematical Physic