julilili42/papers huggingface dataset:
Influence of an inner disc on the orbital evolution of massive planets migrating in resonance
2008-03-19

\\n Context. The formation of resonant planet pairs in exoplanetary systems\\ninvolves planetary migration inside the protoplanetary disc. After a\\nresonant capture, subsequent migration leads to a large increase in\\nplanetary eccentricities, if no damping mechanism is applied. This has\\nled to the conclusion that the migration of resonant planetary systems\\ncannot take place across large radial distances, but must be\\nterminated rapidly by disc dissipation.\\n Aims. We investigate if the presence of an inner disc could supply\\neccentricity damping to the inner planet, and if this effect could\\nexplain observed eccentricities in some planetary systems.\\n Methods. We compute hydrodynamic simulations of giant planets, in\\norbits of a given eccentricity about an inner gas disc, and measure\\nthe effect of the gas disc on the planetary orbital parameters. We\\nperform detailed long-term calculations of the GJ 876 system. We\\ncomplete N-body simulations, which include artificial forces on the\\nplanets that recreate the effect of the inner and outer discs.\\n Results. We find that we cannot neglect the influence of the inner disc,\\nand that the disc could explain the observed eccentricities. In\\nparticular, we reproduce the orbital parameters of a few\\nsystems engaged in 2:1 mean motion resonances: GJ 876, HD 73 526,\\nHD 82 943, and HD 128 311. Analytically, we derive the effect\\nthat the inner disc should have on the inner planet to reach a\\nspecific orbital configuration, for any given damping effect of the\\nouter disc on the outer planet.\\n Conclusions. We conclude that an inner disc, even though difficult to model\\nproperly in hydrodynamical simulations, should be taken into account\\nbecause of its damping effect on the eccentricity of the inner planet.\\nBy including this effect, we can explain quite naturally the observed\\norbital elements of the pairs of known resonant exoplanets.\\n
Analyzing powerAyfor ω meson production in proton–proton collisions
2008-03-19

We report on a determination of the analyzing power Ay in the p→p→ppω reaction studied with the TOF spectrometer located at the COSY-accelerator (Forschungszentrum Jülich, Germany). This spectrometer is very well suited for polarization measurements due to its rotational symmetry and full coverage of the azimuthal angle. For a beam momentum of p=3065MeV/c corresponding to an excess energy of ε=129MeV Ay is found to be compatible with zero.
Structural basis of GM1 ganglioside recognition by simian virus 40
2008-03-20

Simian virus 40 (SV40) has been a paradigm for understanding attachment and entry of nonenveloped viruses, viral DNA replication, and virus assembly, as well as for endocytosis pathways associated with caveolin and cholesterol. We find by glycan array screening that SV40 recognizes its ganglioside receptor GM1 with a quite narrow specificity, but isothermal titration calorimetry shows that individual binding sites have a relatively low affinity, with a millimolar dissociation constant. The high-resolution crystal structure of recombinantly produced SV40 capsid protein, VP1, in complex with the carbohydrate portion of GM1, reveals that the receptor is bound in a shallow solvent-exposed groove at the outer surface of the capsid. Through a complex network of interactions, VP1 recognizes a conformation of GM1 that is the dominant one in solution. Analysis of contacts provides a structural basis for the observed specificity and suggests binding mechanisms for additional physiologically relevant GM1 variants. Comparison with murine Polyomavirus (Polyoma) receptor complexes reveals that SV40 uses a different mechanism of sialic acid binding, which has implications for receptor binding of human polyomaviruses. The SV40–GM1 complex reveals a parallel to cholera toxin, which uses a similar cell entry pathway and binds GM1 in the same conformation.
Plant Classification from Bat-Like Echolocation Signals
2008-03-20

Classification of plants according to their echoes is an elementary component of bat behavior that plays an important role in spatial orientation and food acquisition. Vegetation echoes are, however, highly complex stochastic signals: from an acoustical point of view, a plant can be thought of as a three-dimensional array of leaves reflecting the emitted bat call. The received echo is therefore a superposition of many reflections. In this work we suggest that the classification of these echoes might not be such a troublesome routine for bats as formerly thought. We present a rather simple approach to classifying signals from a large database of plant echoes that were created by ensonifying plants with a frequency-modulated bat-like ultrasonic pulse. Our algorithm uses the spectrogram of a single echo from which it only uses features that are undoubtedly accessible to bats. We used a standard machine learning algorithm (SVM) to automatically extract suitable linear combinations of time and frequency cues from the spectrograms such that classification with high accuracy is enabled. This demonstrates that ultrasonic echoes are highly informative about the species membership of an ensonified plant, and that this information can be extracted with rather simple, biologically plausible analysis. Thus, our findings provide a new explanatory basis for the poorly understood observed abilities of bats in classifying vegetation and other complex objects.
Do the feet of German and Australian children differ in structure? Implications for children's shoe design
2008-03-20

The purpose of this study was to determine whether there were any significant differences in the morphology of the feet of children living on two different continents. The shape and dimensions of the feet of 86 preschool and 419 primary school children from Australia, matched to the same number of German children for age, gender, height and BMI, were compared. The German children display significantly longer and flatter feet relative to their Australian counterparts, whereas the Australian children reveal a significantly smaller ball angle, implying that the forefoot of the Australian children is squarer in shape. These findings imply that footwear must be designed to cater to the unique foot dimensions of children in different continents to ensure that shoe shape matches foot shape. Most footwear companies do not vary the dimensions of their shoe lasts to accommodate intercontinental differences in foot morphology based on racial and/or environmental factors. The results of this study will have immediate implications for the design of comfortable footwear suitable for the developing feet of children.
Zur Hydrolyse von 2,3‐Dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐yliden. Die Kristallstruktur von 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazoliumhydrogencarbonat
2008-03-20

Abstract On the Hydrolysis of 2,3‐Dihydro‐1,3‐di‐ tert ‐butyl‐4,5‐dimethylimidazol‐2‐ylidene. The Crystal Structure of 1,3‐Di‐ tert ‐butyl‐4,5‐dimethylimidazolium Bicarbonate 1,3‐Di‐ tert ‐butyl‐4,5‐dimethylimidazolium bicarbonate ( 7 ), formed on the exposure of 2,3‐dihydro‐1,3‐di‐ tert ‐butyl‐4,5‐dimethylimidazol‐2‐ylidene ( 6 ) towards air, is prepared on the reaction of 6 with ammonium bicarbonate; its crystal structure analysis reveals the presence of dimeric bicarbonate anions linked to each other and to the imidazolium ions with hydrogen bonds.
Enzyme Kinetics: Section 2.6–2.12
2008-03-20

This chapter contains sections titled: Multi-substrate Reactions Nomenclature Random Mechanism Ordered Mechanism Ping-pong Mechanism Product Inhibition in Multi-substrate Reactions Haldane Relationships in Multi-substrate Reactions Mechanisms with more than Two Substrates Other Nomenclatures for Multi-substrate Reactions Derivation of Rate Equations of Complex Enzyme Mechanisms King-Altmann Method Simplified Derivations Applying Graph Theory Combination of Equilibrium and Steady State Approach Kinetic Treatment of Allosteric Enzymes Hysteretic Enzymes Kinetic Cooperativity, the Slow Transition Model pH and Temperature Dependence of Enzymes pH Optimum and Determination of pK Values pH Stability Temperature Dependence Isotope Exchange Isotope Exchange Kinetics Isotope Effects Primary Kinetic Isotope Effect Influence of the Kinetic Isotope Effect on V and Km Other Isotope Effects Special Enzyme Mechanisms Ribozymes Polymer Substrates Kinetics of Immobilized Enzymes External Diffusion Limitation Internal Diffusion Limitation Inhibition of Immobilized Enzymes pH and Temperature Behavior of Immobilized Enzymes Transport Processes Enzyme Reactions at Membrane Interfaces Application of Statistical Methods in Enzyme Kinetics General Remarks Statistical Terms Used in Enzyme Kinetics References
Acute hepatitis A virus infection in Turkey
2008-03-21

Abstract Anti‐HAV IgM positive serum samples from acute phase hepatitis A patients from various areas in Turkey were tested for viral RNA by RT‐PCR (reverse transcriptase polymerase chain reaction), using primer pairs from two different regions of the HAV genome. The PCR products amplified from both genomic regions underwent phylogenetic analyses. A comparison of the regions showed the same genotyping results, and the RT‐PCR‐2 in the 5′NCR demonstrated greater sensitivity compared to RT‐PCR‐1 in the VP1‐P2A region. The majority of the isolates belonged to genotype IB and are related closely to each other; however, two isolates related even more strongly to the HAV HM175 strain. Two (n = 37) RT‐PCR positive sera were classified under genotype IA. A surprising finding emerged for the mean levels of serum transaminases AST and ALT: higher levels were found in patients under 10 years of age compared to older patients. Anti‐HAV IgM levels were determined quantitatively and, in addition, the HAV‐RNA genome equivalents were ascertained by real time RT‐PCR. No evidence was found for an association between viral load and the higher transaminase levels in the younger group. J. Med. Virol. 80:785–790, 2008. © 2008 Wiley‐Liss, Inc.
Localization of overlap modes and topological charge, vortices and monopoles in SU(3) LGT
2008-03-21

We present selected recent results of the QCDSF collaboration on the localization and dimensionality of low overlap eigenmodes and of the topological density in the quenched SU(3) vacuum.We discuss the correlations between the topological structure revealed by overlap fermions without filtering and the confining monopole and P-vortex structure obtained in the Indirect Maximal Center Gauge.
Polyakov loops and SU(2) staggered Dirac spectra
2008-03-21

We consider the spectrum of the staggered Dirac operator with SU(2) gauge fields.Our study is motivated by the fact that the antiunitary symmetries of this operator are different from those of the SU(2) continuum Dirac operator.In this contribution, we investigate in some detail staggered eigenvalue spectra close to the free limit.Numerical experiments in the quenched approximation and at very large β -values show that the eigenvalues occur in clusters consisting of eight eigenvalues each.We can predict the locations of these clusters for a given configuration very accurately by an analytical formula involving Polyakov loops and boundary conditions.The spacing distribution of the eigenvalues within the clusters agrees with the chiral symplectic ensemble of random matrix theory, in agreement with theoretical expectations, whereas the spacing distribution between the clusters tends towards Poisson behavior.
Vortex topology and the continuum limit of lattice gauge theories
2008-03-21

We study the stability of Z_2 topological vortex excitations in d+1 dimensional SU(2) Yang-Mills theory on the lattice at T=0. This is found to depend on d and on the coupling considered. We discuss the connection with lattice artifacts causing bulk transitions in the beta_A-beta_F plane and draw some conclusions regarding the continuum limit of the theory.
Charge Transfer and Polarization Screening at Organic/Metal Interfaces:  Distinguishing between the First Layer and Thin Films
2008-03-22

We studied the core hole screening at organic/metal interfaces using combined photoemission spectroscopy (PES) and X-ray excited Auger electron spectroscopy (XAES) as a function of the organic layer thickness. As a model system for organic semiconductor/metal interfaces, magnesium phthalocyanine was evaporated onto gold foil. It was found that the screening of double hole final states is remarkably increased for molecules directly at the interface, whereas further layers are effected very weakly. The screening mechanism is discussed in terms of both charge transfer and electronic polarization.
The subjective visual vertical in a nonhuman primate
2008-03-24

We perceive the visual world as upright as our visual system used information on the orientation of the body to update the internal representation of the visual scene. In humans, this updating is not perfect, thus leading to distortions of the subjective visual vertical. For small roll-tilt angles (<60 degrees ), subjects overestimate the body tilt (E-effect), whereas for larger angles they underestimate it (A-effect). We wanted to know if monkeys show comparable perceptual distortions as they might help to identify the neural basis of a tilt-independent representation of visual objects at the level of single neurons. In order to answer this question, we trained two monkeys to align an arrow with an upright world-centered reference line whose visibility was varied between trials. Trials were performed at roll-tilt angles chosen from -90 degrees to 90 degrees . The monkeys' responses were precise for trials in which the reference line was visible. However, for the trials in which there was no reference line, their responses reflected an overestimation of body tilt (E-effect-like) very similar to humans. Our ability to demonstrate similar visuo-vestibular illusions in monkeys and man is an important step towards understanding the neural mechanism responsible for the perception of an upright visual world.
An Oligocene ductile strike-slip shear zone: The Uludag Massif, northwest Turkey--Implications for the westward translation of Anatolia
2008-03-25

The Uludağ Massif in northwest Turkey represents an exhumed segment of an Oligocene ductile strike-slip shear zone that is over 225 km long and has ~100 km of right-lateral strike-slip displacement. It forms a faultbounded mountain of amphibolite-facies gneiss and intrusive Oligocene granites. A shear-zone origin for the Uludağ Massif is indicated by: (1) its location at the tip of the active Eskişehir oblique-slip fault, (2) pervasive subhorizontal mineral lineation in the gneisses with a right-lateral sense of slip, (3) foliation with a consistent strike, (4) the presence of a subvertical synkinematic intrusion, and (5) the alignment of the Eskişehir fault, synkinematic metagranite, and the strike of the foliation and mineral lineation. The shear zone nucleated in amphibolite-facies gneisses at peak pressure-temperature (P-T) conditions of 7.0 kbar and 670 °C, and it preserves Eocene (49 Ma) and Oligocene (36–30 Ma) Rb/Sr muscovite and biotite cooling ages. The shear zone was active during the latest Eocene and Oligocene (38–27 Ma), as shown by the crystallization and cooling ages from synkinematic granite. A 27 Ma postkinematic granite marks the termination of shear-zone activity. The 20–21 Ma apatite fi ssion-track (AFT) ages indicate rapid exhumation during the early Miocene. A 14 Ma AFT age from an Uludağ gneiss clast deposited in a neighboring Neogene basin shows that the shear zone was on the surface by the late Miocene. Results of this study indicate that during the Oligocene, crustal-scale right-lateral strikeslip faults were transporting crustal fragments from Anatolia into the north-south– extending Aegean; this implies that the westward translation of Turkey, related to the Hellenic slab suction, started earlier than the Miocene Arabia-Eurasia collision.
Proceedings of the 2008 EDBT Ph.D. workshop
2008-03-25

This volume contains the post workshop proceedings of the EDBT 2008 Ph.D. Workshop. The workshop was held in conjunction with the 11th International Conference on Extending Database Technology (EDBT) on March 25, 2008, in Nantes, France. Continuing in its tradition, the Ph.D. Workshop brings together Ph.D. students in the field of database technology outside of the EDBT conference series. It offers Ph.D. students the opportunity to present, discuss, and receive feedback on their research in a constructive and international environment. One of this year's EDBT 2008 Ph.D. Workshop's highlights was the joint keynote address of Sophie Cluet and Serge Abiteboul. Their brilliant and revealing talk titled On (beautiful) lives in academia and after was quite fascinating for all participants of the workshop. We are very glad that these two extraordinary researchers allowed us to benefit from their comprehensive knowledge and opened our minds for both, conventional and unconventional careers paths.
Tighter focusing with a parabolic mirror
2008-03-26

We demonstrate experimentally and theoretically that a parabolic mirror (PM) with a high numerical aperture (NA) of 1 focuses a radially polarized laser mode to the smallest diffraction-limited spot at a fixed NA and wavelength, having an area of 0.134 lambda(2). The measurements were performed with a confocal microscope, using the PM as a focusing and collecting element. The results stand in accordance with the theoretical calculations presented by Davidson and Bokor [Opt. Lett. 29, 1318 (2004)], who predicted a reduction in the total focal spot size of 43% as compared with an aplanatic lens.
Laparoscopic Sleeve Gastrectomy: Standardized Technique of a Potential Stand‐alone Bariatric Procedure in Morbidly Obese Patients
2008-03-26

Abstract Background The aim of this study was to define a standardized technique for laparoscopic sleeve gastrectomy in the morbidly obese patient. Methods There are several surgical options for the morbidy obese patient. In general, there are the restrictive procedures [e.g., laparoscopic adjustable gastric banding (LAGB)] and the malabsorptive procedures [e.g. laparoscopic Roux‐en‐Y gastric bypass (LRYGBP)]. Those techniques are already standardized. The laparoscopic sleeve gastrectomy (LSG) seems to have some advantages over both procedures, but it is not standardized yet, and so there can be no comparison between the different techniques. In our center we have standardized the LSG technique with respect to abdominal access and narrowness of the gastric sleeve. After dissection of the greater omentum and the short gastric vessels, the greater curvature is resected along a 34‐Fr gastric tube using the Endo‐GIA. The remaining gastric sleeve has a volume of about 100 ml. Results The standardized LSG procedure is presented step by step. A comparison of operative data and early outcome with a matched group of patients with adjustable gastric banding showed no difference between the two techniques with respect to operating time, surgical complications, and weight loss 6 months after surgery. Conclusion With our standardized LSG technique it is possible to evaluate the positive aspects of the LSG compared with other standardized bariatric procedures like LAGB or LRYGBP.
Role of maternal glucocorticoid inducible kinase SGK1 in fetal programming of blood pressure in response to prenatal diet
2008-03-26

Maternal stress and malnutrition modify intrauterine fetal development with impact on postnatal blood pressure, nutrient, water, and electrolyte metabolism. The present study explored the possible involvement of maternal serum- and glucocorticoid-inducible kinase (SGK)-1 in fetal programming of blood pressure. To this end, wild-type ( sgk1 +/+ ) male mice were mated with SGK1 knockout ( sgk1 −/− ) female mice, and sgk1 −/− males with sgk1 +/+ females, resulting in both cases in heterozygotic ( sgk1 −/+ ) offspring. Following prenatal protein restriction, the offspring of sgk1 +/+ mothers gained weight significantly slower and had significantly higher blood pressure after birth. Moreover, a sexual dimorphism was apparent in fasting blood glucose and plasma corticosterone concentrations, with higher levels in female offspring. In contrast, prenatal protein restriction of sgk1 −/− mothers had no significant effect on postnatal weight gain, blood pressure, plasma glucose concentration, or corticosterone levels, irrespective of offspring sex. Plasma aldosterone concentration, urinary flow rates, and urinary excretions of Na + and K + were not significantly modified by either maternal genotype or nutritional manipulation. In conclusion, maternal signals mediated by SGK1 may play a decisive role in fetal programming of hypertension induced by prenatal protein restriction.
NOD2/CARD15 Gene Variants Are Linked to Failure of Antibiotic Treatment in Perianal Fistulating Crohn's Disease
2008-03-26

The study result suggests a substantial contribution of NOD2/CARD15 to the antibiotic treatment outcome of perianal fistulating CD. NOD2/CARD15 variants may predispose to an altered intestinal microflora in perianal fistulas that is less responsive to antibiotic treatment.
Formation of Carbon Coatings on SiC Fibers by Selective Etching in Halogens and Supercritical Water
2008-03-26

Carbon coatings can be obtained on silicon carbide fibers by selective etching that removes silicon from the surface layer of the fiber. A gas or fluid (chlorine, supercritical water, etc.) can be used. This approach allows us to solve the problems of uniformity and adherence of coatings, as well as avoid bridging of filaments. The principal difference between the suggested method and other approaches is that the coating is not deposited on the surface of the carbide; rather the carbide surface is converted into carbon. This method can provide a simple and inexpensive route to carbon coatings (thickness from 10 nm to several microns) for a wide range of applications. It is shown that hydrothermal leaching produces a smooth and uniform carbon film on the surface of polymer-derived SiC fibers, however treatment of CVD fibers requires more efforts. Similar carbon coatings have been obtained by halogenation of SiC fibers in chlorine-containing environments.
Silicon Nitride at Very High Temperatures: Bubble and Pit Formation
2008-03-26

From oxidation studies of sintered ceramics and pure Si3N4 and phase equilibrium studies it is concluded that the bubble formation in scales and the bloating of powder compacts have a common cause. This common cause is thought to be the formation of ”native oxides”, which are metastable amorphous solids of the type SiNxOy. As the eutectic temperature of the system is approached they recrystallise or decompose. The latter case leads to the bubbling/bloating. In pure Si3N4 this is in the vicinity of 1600°C at atmospheric pressure and defines the upper HT-limit of use. Pit formation seems to require bubble formation but not vice versa. Pits probably form at surface defects. They interact with microcracks forming during mechanical loading in oxidising atmospheres at high temperatures.
Thin‐Film Properties of DNA and RNA Bases: A Combined Experimental and Theoretical Study
2008-03-27

Abstract The structures of the DNA and RNA bases cytosine, uracil, and thymine in thin films with a nominal film thickness of about 20 nm are studied by using X‐ray photoemission spectroscopy (XPS) and Fourier‐transform infrared spectroscopy. The molecules are evaporated in situ from powder on a gold foil. The experimental results indicate that cytosine is composed of two energetically close tautomeric forms, whereas uracil and thymine exist in only one tautomeric form. Additionally, quantum chemical calculations are performed to complement the experimental results. The relative energies of the tautomeric forms of cytosine, uracil, and thymine are calculated using Hartree–Fock (HF), density functional theory (DFT), and post‐HF methods. Furthermore, the assignment of the XPS spectra is supported by using simple model considerations employing Koopmans ionization energies and Mulliken net atomic charges.