Showing papers by "Romanian Academy published in 2010"
TL;DR: This study clearly demonstrates that oxidative stress damage occurs in patients with mild cognitive impairment and AD, and some enzymatic markers of oxidative stress are similar in MCI and AD patients, suggesting that oxidative damage could be one important aspect for the onset of AD.
328 citations
University of Sydney1, University of Birmingham2, University of British Columbia3, University of Vienna4, Indian Institute of Astrophysics5, Pierre-and-Marie-Curie University6, University of South Africa7, University of Toulouse8, University of Paris9, Saint Mary's University10, Katholieke Universiteit Leuven11, Aarhus University12, Ames Research Center13, Las Cumbres Observatory Global Telescope Network14, Space Telescope Science Institute15, University of Liège16, Kavli Institute for Theoretical Physics17, University of Porto18, Hungarian Academy of Sciences19, Beijing Normal University20, Queen Mary University of London21, Romanian Academy22, Max Planck Society23
TL;DR: In this paper, the authors measured solar-like oscillations in red giants using time-series photometry from the first 34 days of science operations of the Kepler Mission and found a strong correlation between the large separation of the oscillations and the frequency of maximum power (νmax).
Abstract: We have measured solar-like oscillations in red giants using time-series photometry from the first 34 days of science operations of the Kepler Mission. The light curves, obtained with 30 minute sampling, reveal clear oscillations in a large sample of G and K giants, extending in luminosity from the red clump down to the bottom of the giant branch. We confirm a strong correlation between the large separation of the oscillations (Δν) and the frequency of maximum power (νmax). We focus on a sample of 50 low-luminosity stars (νmax > 100 μHz, L <~ 30 L sun) having high signal-to-noise ratios and showing the unambiguous signature of solar-like oscillations. These are H-shell-burning stars, whose oscillations should be valuable for testing models of stellar evolution and for constraining the star formation rate in the local disk. We use a new technique to compare stars on a single echelle diagram by scaling their frequencies and find well-defined ridges corresponding to radial and non-radial oscillations, including clear evidence for modes with angular degree l = 3. Measuring the small separation between l = 0 and l = 2 allows us to plot the so-called C-D diagram of δν02 versus Δν. The small separation δν01 of l = 1 from the midpoint of adjacent l = 0 modes is negative, contrary to the Sun and solar-type stars. The ridge for l = 1 is notably broadened, which we attribute to mixed modes, confirming theoretical predictions for low-luminosity giants. Overall, the results demonstrate the tremendous potential of Kepler data for asteroseismology of red giants.
272 citations
University of Porto1, INAF2, University of Wrocław3, Los Alamos National Laboratory4, University of Central Lancashire5, Spanish National Research Council6, Paris Diderot University7, Ames Research Center8, Las Cumbres Observatory Global Telescope Network9, Aarhus University10, Space Telescope Science Institute11, University of Liège12, New Mexico State University13, Centre national de la recherche scientifique14, Camosun College15, Hungarian Academy of Sciences16, Kiepenheuer Institut für Sonnenphysik17, Romanian Academy18
TL;DR: In this article, a new observational classification scheme is proposed that takes into account the amplitude as well as the frequency and is applied to categorize 234 stars as δSct, γDor, δ Sct/γDor or γ Dor/Sct hybrids.
Abstract: Observations of the pulsations of stars can be used to infer their interior structure and test theoretical models. The main-sequence γ Doradus (Dor) and δ Scuti (Sct) stars with masses 1.2-2.5 M ☉ are particularly useful for these studies. The γ Dor stars pulsate in high-order g-modes with periods of order 1 day, driven by convective blocking at the base of their envelope convection zone. The δ Sct stars pulsate in low-order g- and p-modes with periods of order 2 hr, driven by the κ mechanism operating in the He II ionization zone. Theory predicts an overlap region in the Hertzsprung-Russell diagram between instability regions, where hybrid stars pulsating in both types of modes should exist. The two types of modes with properties governed by different portions of the stellar interior provide complementary model constraints. Among the known γ Dor and δ Sct stars, only four have been confirmed as hybrids. Now, analysis of combined Quarter 0 and Quarter 1 Kepler data for hundreds of variable stars shows that the frequency spectra are so rich that there are practically no pure δ Sct or γ Dor pulsators, i.e., essentially all of the stars show frequencies in both the δ Sct and the γ Dor frequency range. A new observational classification scheme is proposed that takes into account the amplitude as well as the frequency and is applied to categorize 234 stars as δ Sct, γ Dor, δ Sct/γ Dor or γ Dor/δ Sct hybrids.
208 citations
TL;DR: Bacterial activity of acyl-hydrazone and its complexes were studied against gram-positive bacteria: Staphylococcus aureus, Bacillus subtilis and gram-negative bacteria: Pseudomonas aeruginosa, Escherichia coli by using minimum inhibitory concentrations (MICs) method.
205 citations
High Altitude Observatory1, University of Porto2, University of Sheffield3, Las Cumbres Observatory Global Telescope Network4, Space Telescope Science Institute5, Ames Research Center6, Search for extraterrestrial intelligence7, University of Toulouse8, INAF9, Spanish National Research Council10, University of Geneva11, Beijing Normal University12, Harvard University13, Indian Institute of Astrophysics14, Canadian Space Agency15, Los Alamos National Laboratory16, Pierre-and-Marie-Curie University17, Konkoly Thege Miklós Astronomical Institute18, Halifax19, University of Birmingham20, University of Sydney21, Hungarian Academy of Sciences22, Center for Turbulence Research23, University of Vienna24, European Southern Observatory25, University of Liège26, University of South Africa27, Kiepenheuer Institut für Sonnenphysik28, Paris Diderot University29, Max Planck Society30, Romanian Academy31, University of Colorado Boulder32, University of Oslo33
TL;DR: In this article, preliminary asteroseismic results from Kepler on three G-type stars are presented, made at one-minute cadence during the first 33.5 days of science operations, reveal high signal-to-noise solar-like oscillation spectra in all three stars: about 20 modes of oscillation may be clearly distinguished in each star.
Abstract: We present preliminary asteroseismic results from Kepler on three G-type stars. The observations, made at one-minute cadence during the first 33.5 days of science operations, reveal high signal-to-noise solar-like oscillation spectra in all three stars: about 20 modes of oscillation may be clearly distinguished in each star. We discuss the appearance of the oscillation spectra, use the frequencies and frequency separations to provide first results on the radii, masses, and ages of the stars, and comment in the light of these results on prospects for inference on other solar-type stars that Kepler will observe.
181 citations
TL;DR: A significant decrease in GPX specific activity and also a significant increase of MDA levels in schizophrenic patients, compared to age-matched control group, regardless of their type of treatment, are found.
161 citations
TL;DR: In this paper, a landslide susceptibility assessment at national level was accomplished using a Landslide Susceptibility Index (LSI) computed in GIS, which considers and weights the main factors that control landslide activity: lithology, slope gradient, maximum rainfall in 24-h, land use, seismicity and local relief.
140 citations
TL;DR: This work proposes and analyzes iterative methods to solve a conforming finite element approximation of the coupled problem of the Navier–Stokes and Darcy equations.
Abstract: We consider a differential system based on the coupling of the Navier–Stokes and Darcy equations for modeling the interaction between surface and porous-media flows. We formulate the problem as an interface equation, we analyze the associated (nonlinear) Steklov–Poincare operators, and we prove its well-posedness. We propose and analyze iterative methods to solve a conforming finite element approximation of the coupled problem.
134 citations
TL;DR: This work employed a high-throughput screening approach to discover a novel bitter receptor antagonist (GIV3727) that inhibits activation of hTAS2R31 by saccharin and acesulfame K, two common artificial sweeteners.
133 citations
University of Vienna1, Konkoly Thege Miklós Astronomical Institute2, University of Central Lancashire3, Space Telescope Science Institute4, Aarhus University5, Las Cumbres Observatory Global Telescope Network6, University of Nice Sophia Antipolis7, University of Sydney8, INAF9, University of Florida10, University of Concepción11, Camosun College12, Romanian Academy13, Ames Research Center14
TL;DR: In this paper, the first results of the analyses of selected RR Lyrae stars for which data have been obtained by the Kepler Mission are presented, showing that at least 40% of the RR Lyrase stars in their sample showing modulation, confirming the high incidence rate that was only found in recent highprecision studies.
Abstract: We present the first results of our analyses of selected RR Lyrae stars for which data have been obtained by the Kepler Mission. As expected, we find a significant fraction of the RRab stars to show the Blazhko effect, a still unexplained phenomenon that manifests itself as periodic amplitude and phase modulations of the light curve, on timescales of typically tens to hundreds of days. The long time span of the Kepler Mission of 3.5 yr and the unprecedentedly high precision of its data provide a unique opportunity for the study of RR Lyrae stars. Using data of a modulated star observed in the first roll as a showcase, we discuss the data, our analyses, findings, and their implications for our understanding of RR Lyrae stars and the Blazhko effect. With at least 40% of the RR Lyrae stars in our sample showing modulation, we confirm the high incidence rate that was only found in recent high-precision studies. Moreover, we report the occurrence of additional frequencies, beyond the main pulsation mode and its modulation components. Their half-integer ratio to the main frequency is reminiscent of a period doubling effect caused by resonances, observed for the first time in RR Lyrae stars.
133 citations
TL;DR: Investigation of the presence of contagious cry phenomenon in infancy shows that during the presentation of a pain cry sound, 1, 3, 6, and 9 months old infants manifest increased vocal and facial expressions of distress and these affect sharing reactions do not decrease with age.
Abstract: Newborns cry in response to another newborn cry and researchers agree that these are the very early signs of empathy development. Yet, little is known about the development of these affect sharing reactions in infancy, beyond the very first few days after birth. The aim of this study is to investigate the presence of contagious cry phenomenon in infancy. Infants aged 1-, 3-, 6-, and 9-month-old were presented with the sound of another infant cry vocalizations. Their emotional reactions were recorded in terms of vocal (presence of vocal distress, latency, and intensity) and facial (anger and sadness) expressions of emotions. Results show that during the presentation of a pain cry sound, 1, 3, 6, and 9 months old infants manifest increased vocal and facial expressions of distress. These affect sharing reactions do not decrease with age. Both boys and girls manifest similar levels of contagious crying reactions. The results are discussed in terms of early empathy development.
TL;DR: In this article, an analytic approximate technique, namely optimal homotopy asymptotic method (OHAM), is employed to solve nonlinear oscillations of a particle which moves on a rotating parabola.
TL;DR: In this paper, the spatial distribution of amphibians from a Romanian rural landscape where land-use is still largely traditional is investigated, and the occurrence of nine amphibian species and species richness is related to measures of composition and configuration of the landscape surrounding 54 ponds at three spatial scales: circular areas of 400, 600 and 800 m radii.
TL;DR: A complex composite system with multifunctional role: bone graft material and hyperthermia generator necessary for bone cancer therapy, obtained by a co-precipitation method and characterised by XRD, FTIR and SEM.
Abstract: Our purpose was obtaining and characterizing a complex composite system with multifunctional role: bone graft material and hyperthermia generator necessary for bone cancer therapy. The designed system was a magnetite enriched collagen/hydroxyapatite composite material, obtained by a co-precipitation method. Due to the applied electromagnetic field the magnetite will induce hyperthermia and cause tumoral cell apoptosis. The complex bone graft system was characterised by XRD, FTIR and SEM, while the hyperthermia was quantify by measuring the temperature increase due to the applied alternative electromagnetical field.
TL;DR: In this article, the crystal structure of 1-phenyl-2,3-dimethyl-4-(N-3-formyl-6-methyl-chromone)-3-pyrazolin-5-one (HL) has been determined by X-ray diffraction studies, as well as the one of its copper(II) complex [CuL(OAc)]·CH3OH which contains an anionic ligand and an acetate in the coordination sphere of the metal.
University of Birmingham1, Katholieke Universiteit Leuven2, University of Sydney3, University of California, Santa Barbara4, Las Cumbres Observatory Global Telescope Network5, Space Telescope Science Institute6, Aarhus University7, Ames Research Center8, Keele University9, University of Göttingen10, University of Central Lancashire11, INAF12, Hungarian Academy of Sciences13, Romanian Academy14
TL;DR: In this article, a red giant with solar-like oscillations in an eclipsing binary observed with the NASA Kepler satellite is presented, and the stellar parameters of the red giant from spectra and the asteroseismic mass and radius from the oscillations are computed.
Abstract: Oscillating stars in binary systems are among the most interesting stellar laboratories, as these can provide information on the stellar parameters and stellar internal structures. Here we present a red giant with solar-like oscillations in an eclipsing binary observed with the NASA Kepler satellite. We compute stellar parameters of the red giant from spectra and the asteroseismic mass and radius from the oscillations. Although only one eclipse has been observed so far, we can already determine that the secondary is a main-sequence F star in an eccentric orbit with a semi-major axis larger than 0.5 AU and orbital period longer than 75 days.
TL;DR: The Carpathian-Pannonian Pannonian Region (CPR) has a diverse compositional variation in response to a complex interplay of subduction with rollback, back-arc extension, collision, slab break-off, delamination, strike-slip tectonics and microplate rotations, as well as to further evolution of magmas in the crustal environment by processes of differentiation, crustal contamination, anatexis and magma mixing as mentioned in this paper.
Abstract: Neogene to Quaternary volcanic/magmatic activity in the Carpathian-Pannonian Region (CPR) occurred between 21 and 0.1 Ma with a distinct migration in time from west to east. It shows a diverse compositional variation in response to a complex interplay of subduction with rollback, back-arc extension, collision, slab break-off, delamination, strike-slip tectonics and microplate rotations, as well as in response to further evolution of magmas in the crustal environment by processes of differentiation, crustal contamination, anatexis and magma mixing. Since most of the primary volcanic forms have been affected by erosion, especially in areas of post-volcanic uplift, based on the level of erosion we distinguish: (1) areas eroded to the basement level, where paleovolcanic reconstruction is not possible; (2) deeply eroded volcanic forms with secondary morphology and possible paleovolcanic reconstruction; (3) eroded volcanic forms with remnants of original morphology preserved; and (4) the least eroded volcanic forms with original morphology quite well preserved. The large variety of volcanic forms present in the area can be grouped in a) monogenetic volcanoes and b) polygenetic volcanoes and their subsurface/intrusive counterparts that belong to various rock series found in the CPR such as calc-alkaline magmatic rock-types (felsic, intermediate and mafic varieties) and alkalic types including K-alkalic, shoshonitic, ultrapotassic and Na-alkalic. The following volcanic/subvolcanic forms have been identified: (i) domes, shield volcanoes, effusive cones, pyroclastic cones, stratovolcanoes and calderas with associated intrusive bodies for intermediate and basic calclkaline volcanism; (ii) domes, calderas and ignimbrite/ash-flow fields for felsic calc-alkaline volcanism and (iii) dome flows, shield volcanoes, maars, tuffcone/tuff-rings, scoria-cones with or without related lava flow/field and their erosional or subsurface forms (necks/ plugs, dykes, shallow intrusions, diatreme, lava lake) for various types of K- and Na-alkalic and ultra-potassic magmatism. Finally, we provide a summary of the eruptive history and distribution of volcanic forms in the CPR using several sub-region schemes.
TL;DR: Three of the 12 tested compounds showed moderate antitumor activity, one of them being chosen for the 5-dose assay and presented logGI(50) values up to -5.75.
TL;DR: Complex compounds of copper(II) were synthesized, structurally characterized and tested for biological activity, proving both antibacterial and antiproliferative activity.
TL;DR: In this article, an analytic approximate technique, namely Optimal Homotopy Asymptotic Method (OHAM), is employed for non-linear oscillations of planar, flexural large amplitude free vibrations of a slender, inextensible cantilever beam carrying a lumped mass with rotary inertia at an intermediate position along its span.
Abstract: This paper is concerned with analytical treatment of non-linear oscillations of planar, flexural large amplitude free vibrations of a slender, inextensible cantilever beam carrying a lumped mass with rotary inertia at an intermediate position along its span. An analytic approximate technique, namely Optimal Homotopy Asymptotic Method (OHAM) is employed for this purpose. It is proved that OHAM provide accurate solutions for large amplitudes and large modal constants in the considered nonlinear equations, when other classical methods fail. Our procedure provides us with a convenient way to optimally control the convergence of solution, such that the accuracy is always guaranteed. An excellent agreement of the approximate frequencies and periodic solutions with the numerical results and published results has been demonstrated. Two examples are given and the results reveal that this procedure is very effective, simple and accurate. This paper demonstrates the general validity and the great potential of the OHAM for solving strongly nonlinear problems.
TL;DR: A new approach combining the features of the homotopy concept with an efficient computational algorithm which provides a simple and rigorous procedure to control the convergence of the solution is proposed to find accurate analytical explicit solutions for some oscillators with discontinuities and a fractional power restoring force.
Abstract: In this paper a new approach combining the features of the homotopy concept with an efficient computational algorithm which provides a simple and rigorous procedure to control the convergence of the solution is proposed to find accurate analytical explicit solutions for some oscillators with discontinuities and a fractional power restoring force which is proportional to sign(x). A very fast convergence to the exact solution was proved, since the second-order approximation lead to very accurate results. Comparisons with numerical results are presented to show the effectiveness of this method. Four numerical applications prove the accuracy of the method, which works very well for the whole range of initial amplitudes. The obtained results prove the validity and efficiency of the method, which can be easily extended to other strongly nonlinear problems.
TL;DR: In this article, the changes in structure of lime wood (Tilia cordata mill) decayed by Trichoderma viride pers. have been investigated by FT-IR and 2D IR correlation spectroscopy.
TL;DR: In this article, a mathematical model focusing on key events of the cell invasion process is presented, where three equations of the corresponding coupled system describe the behavior of the invasive cells, the extracellular matrix and the degradative enzymes.
Abstract: In this paper, we analyze a mathematical model focusing on key events of the cell invasion process. The three equations of the corresponding coupled system describe the behavior of the invasive cells, the extracellular matrix and the degradative enzymes. We employ a fix-point method and a priori estimates to prove local and global existence, uniqueness and regularity properties of the solutions. Our approach enable us to find estimates that are uniform in time. This is essential in proving, in the last part of the paper, new results that establish the asymptotic behavior of the solutions.
University of Virginia1, University of Amsterdam2, Romanian Academy3, ASTRON4, European Space Agency5, University of Southampton6, University of Wisconsin-Madison7, Leiden University8, Swinburne University of Technology9, Paris Diderot University10, Universities Space Research Association11, Goddard Space Flight Center12, Vassar College13, University of Michigan14, Joint Institute for VLBI in Europe15, University of Manchester16
TL;DR: In this paper, the radio emission of the neutron star X-ray binary Aquila X-1 was observed with unprecedented radio coverage and simultaneous point-X-ray observations, and it was shown that radio quenching is consistent with being triggered at state transitions, both from the hard to the soft spectral state and vice versa.
Abstract: The 2009 November outburst of the neutron star X-ray binary Aquila X-1 (Aql X-1) was observed with unprecedented radio coverage and simultaneous pointed X-ray observations, tracing the radio emission around the full X-ray hysteresis loop of the outburst for the first time. We use these data to discuss the disk-jet coupling, finding the radio emission to be consistent with being triggered at state transitions, both from the hard to the soft spectral state and vice versa. Our data appear to confirm previous suggestions of radio quenching in the soft state above a threshold X-ray luminosity of ~10% of the Eddington luminosity. We also present the first detections of Aql X-1 with very long baseline interferometry, showing that any extended emission is relatively diffuse and consistent with steady jets rather than arising from discrete, compact knots. In all cases where multi-frequency data were available, the source radio spectrum is consistent with being flat or slightly inverted, suggesting that the internal shock mechanism that is believed to produce optically thin transient radio ejecta in black hole X-ray binaries is not active in Aql X-1.
TL;DR: This note is a short and informal introduction to this research area, introducing a few basic notions, research topics, types of results, and pointing out to some relevant references.
TL;DR: In this paper, the solvent effects on the wavenumbers of the absorption band maxima (ṽmax) were discussed using the following solvent parameters, refractive index, n, dielectric constant, e and empirical Kamlet-Taft solvent parameters.
TL;DR: In this article, a starch-based synthetic route was used for the preparation of (Zn,Al,Co)-starch gel precursors using FTIR and thermal analysis, while their corresponding oxides were characterized with FTIR, NIR-UV-Vis spectroscopy, XRD and SEM.
TL;DR: The data showed the formation of mineralized foci by differentiation of hMSCs to human primary osteoblasts after cultivation in osteogenic media on RF-sputtered films and the capacity of B-type CHA coating to support MSCs adhesion and osteogenic differentiation ability.
Abstract: In this work, an improved version of the radio frequency magnetron sputtering (RF-MS) technique was used to prepare highly adherent B-type carbonated hydroxylapatite (B-CHA) thin films. Fourier transform infrared spectroscopy (FTIR) and grazing incidence X-ray diffraction studies proved that the coatings maintained the composition and revealed the polycrystalline structure of HA. Scanning electron microscopy analysis showed that the CHA films are rough and exhibit a homogeneous microstructure. Energy-dispersive X-ray spectroscopy (EDX) mapping demonstrated a uniform distribution of the Ca and P cations while a Ca/P ratio of 1.8 was found. In addition, the FTIR experiments showed a remarkable reproducibility of the nanostructures. Human mesenchymal stem cells (hMSCs), in vitro differentiated osteoblasts, and explanted bone cells were grown over the surface of CHA coatings for periods between a few hours and 21 days. Osteoprogenitor cells maintained viability and characteristic morphology after adhesion on CHA coatings. Ki67-positive osteoblasts were the evidence of cell proliferation events. Cells showed positive staining for markers of osteoblast phenotype such as collagen type I, bone sialoprotein and osteonectin. Our data showed the formation of mineralized foci by differentiation of hMSCs to human primary osteoblasts after cultivation in osteogenic media on RF-sputtered films. The results demonstrate the capacity of B-type CHA coating to support MSCs adhesion and osteogenic differentiation ability.
TL;DR: In this article, the action of soft-rot fungus Chaetomium globosum has been studied and the decayed lime wood samples were observed for different periods of exposure The degree of decay was determined by weight loss which was of 504% after 133 days.
01 Aug 2010
TL;DR: In this paper, the authors present the failure analysis of a broken Francis turbine runner blade, which appeared some months after the welding repair work realized in situ on fatigue cracks initiated near to the trailing edge at the junction with the crown.
Abstract: The variable demand on the energy market requires great flexibility in operating hydraulic turbines. Therefore, turbines are frequently operated over an extended range of regimes. Francis turbines operating at partial load present pressure fluctuations due to the vortex rope in the draft tube cone. This phenomenon generates strong vibrations and noise that may produce failures on the mechanical elements of the machine. This paper presents the failure analysis of a broken Francis turbine runner blade. The failure appeared some months after the welding repair work realized in situ on fatigue cracks initiated near to the trailing edge at the junction with the crown, where stress concentration occurs. In order to determine the causes that led to the fracture of the runner blade, the metallographic investigations on a sample obtained from the blade is carried out. The metallographic investigations included macroscopic and microscopic examinations, both performed with light and scanning electron microscopy, as well as EDX - analyses. These investigations led to the conclusion, that the cracking of the blade was caused by fatigue, initiated by the surface unevenness of the welding seam. The failure was accelerated by the hydrogen embrittlement of the filling material, which appeared as a consequence of improper welding conditions. In addition to the metallographic investigations, numerical computations with finite element analysis are performed in order to evaluate the deformation and stress distribution on blade.