Romanian Academy

About: Romanian Academy is a archive organization based out in Bucharest, Romania. It is known for research contribution in the topics: Population & Nonlinear system. The organization has 3662 authors who have published 10491 publications receiving 146447 citations. The organization is also known as: Academia Română & Societatea Literară Română.

The linear quadratic optimization problems for a class of linear stochastic systems with multiplicative white noise and Markovian jumping

Abstract: In this paper, the linear quadratic optimization problem for a class of linear stochastic systems subject both to multiplicative white noise and Markovian jumping is investigated. Two classes of admissible controls are considered. One of these classes contains controls with additional property that corresponding trajectories tend to zero (in mean square) when tends to /spl infin/, while concerning the controls contained in the second class of admissible controls there is not any stability assumption. In the optimization problem over the first class of admissible controls, the cost functional could have indefinite sign of weights matrices. An iterative procedure to compute the maximal solution of the systems of generalized Riccati equations is provided. A numerical example to illustrate the applicability of the iterative procedure is given.

Tertiary-Quaternary subduction processes and related magmatism in the Alpine-Mediterranean region

Abstract: During Tertiary to Quaternary times, convergence between Eurasia and Africa resulted in a variety of collisional orogens and different styles of subduction in the Alpine-Mediterranean region. Characteristic features of this area include arcuate orogenic belts and extensional basins, both of which can be explained by roll-back of subducted slabs and retreating subduction zones. After cessation of active subduction, slab detachment and post-collisional gravitational collapse of the overthickened lithosphere took place. This complex tectonic history was accompanied by the generation of a wide variety of magmas. Most of these magmas (e.g. low-K tholeiitic, calc-alkaline, shoshonitic and ultrapotassic types) have trace element and isotopic fingerprints that are commonly interpreted to reflect enrichment of their source regions by subduction-related fluids. Thus, they can be considered as 9subduction-related9 magmas irrespective of their geodynamic relationships. Intraplate alkali basalts are also found in the region and generally postdated the 9subduction-related9 volcanism. These mantle-derived magmas have not (or only slightly) been influenced by subduction-related enrichment. This paper summarizes the geodynamic setting of the Tertiary-Quaternary 9subduction-related9 magmatism in the various segments of the Alpine-Mediterranean region (Betic-Alboran-Rif province, Central Mediterranean, the Alps, Carpathian-Pannonian region, Dinarides and Hellenides, Aegean and Western Anatolia), and discusses the main characteristics and compositional variation of the magmatic rocks. Radiogenic and stable isotope data indicate the importance of continental crustal material in the genesis of these magmas. Interaction with crustal material probably occurred both in the upper mantle during subduction (9source contamination9) and in the continental crust during ascent of mantle-derived magmas (either by mixing with crustal melts or by crustal contamination). The 87 Sr/ 86 Sr and 206 Pb/ 204 Pb isotope ratios indicate that an enriched mantle component, akin to the source of intraplate alkali mafic magmas along the Alpine foreland, played a key role in the petrogenesis of the 9subduction-related9 magmas of the Alpine-Mediterranean region. This enriched mantle component could be related to mantle plumes or to long-term pollution (deflection of the central Atlantic plume and recycling of crustal material during subduction) of the shallow mantle beneath Europe since the late Mesozoic. In the first case, subduction processes could have had an influence in generating asthenospheric flow by deflecting nearby mantle plumes as a result of slab roll-back or slab break-off. In the second case, the variation in the chemical composition of the volcanic rocks in the Mediterranean region can be explained by 9statistical sampling9 of the strongly inhomogeneous mantle followed by variable degrees of crustal contamination.

Shift of large-scale atmospheric systems over Europe during late MIS 3 and implications for Modern Human dispersal

Abstract: Understanding the past dynamics of large-scale atmospheric systems is crucial for our knowledge of the palaeoclimate conditions in Europe. Southeastern Europe currently lies at the border between Atlantic, Mediterranean, and continental climate zones. Past changes in the relative influence of associated atmospheric systems must have been recorded in the region’s palaeoarchives. By comparing high-resolution grain-size, environmental magnetic and geochemical data from two loess-palaeosol sequences in the Lower Danube Basin with other Eurasian palaeorecords, we reconstructed past climatic patterns over Southeastern Europe and the related interaction of the prevailing large-scale circulation modes over Europe, especially during late Marine Isotope Stage 3 (40,000–27,000 years ago). We demonstrate that during this time interval, the intensification of the Siberian High had a crucial influence on European climate causing the more continental conditions over major parts of Europe, and a southwards shift of the Westerlies. Such a climatic and environmental change, combined with the Campanian Ignimbrite/Y-5 volcanic eruption, may have driven the Anatomically Modern Human dispersal towards Central and Western Europe, pointing to a corridor over the Eastern European Plain as an important pathway in their dispersal.

Role of MicroRNA in Endothelial Dysfunction and Hypertension

Abstract: Purpose of Review Hypertension is either a cause or a consequence of the endothelial dysfunction and a major risk factor for cardiovascular disease (CVD). In vitro and in vivo studies established that microRNAs (miRNAs) are decisive for endothelial cell gene expression and function in various pathological conditions associated with CVD. This review provides an overview of the miRNA role in controlling the key connections between endothelial dysfunction and hypertension.

Space Velocities of Southern Globular Clusters. IV. First Results for Inner Galaxy Clusters

Abstract: We have measured the absolute proper motions of four low-latitude, inner Galaxy globular clusters. These clusters are NGC 6266 (M62), NGC 6304, NGC 6316, and NGC 6723. The proper motions are on the Hipparcos system, since no background extragalactic objects are found in these high-extinction regions. The proper-motion uncertainties range between 0.3 and 0.6 mas yr � 1 . We discuss the kinematics of these clusters and of three additional bulge clusters—NGC 6522, NGC 6528, and NGC 6553—whose proper motions with respect to bulge stars had been determined previously. We find that all of the clusters have velocities that confine them to the bulge region. Of the three metal-poor clusters ([Fe/H] < � 1.0), NGC 6522, and NGC 6723 have kinematics consistent with halo membership. The third cluster, NGC 6266 however, appears to belong to a rotationally supported system. Of the four metal-rich clusters ([Fe/H] �� 1.0), NGC 6304 and NGC 6553 also have kinematics consistent with membership to a rotationally supported system. NGC 6528 has kinematics, metallicity, and mass that argue in favor of a genuine Milky Way bar cluster. NGC 6316’s kinematics indicate membership to a hotter system than the bar.