258 research outputs found

    Population changes in Ottoman Anatolia during the 16th and 17th centuries: The "demographic crisis" reconsidered

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    Whatever the fruits of discussing the problem at such a theoretical level, in the case of Anatolia it is perhaps more important to bear in mind the geographical dimension of the population changes in the late-16th- and early-17th-century Ottoman Empire. The crucial question is how representative the cases of demographic pressure in Anatolia described here were as far as the whole empire was concerned. Furthermore, one may ask the same question for Anatolia only, considering the fact that in some parts of Anatolia the population seems to have remained within reasonable limits, although substantial growth in the 16th century was a general phenomenon throughout the Empire. It is therefore imperative to pay attention to voices that emphasize regional differences in terms of demographic changes-differences that depended largely on the quality and quantity of the land, climatic conditions, economic opportunities, and, as Karen Barkey rightly suggests, the patron-client relations at the local level and in the empire in general. It is also clear that population growth does not necessarily or automatically mean "pressure." What this study shows in this respect is that one can speak of such pressure in at least some parts of the empire-in this case, the north-central Anatolian province of Rum. Whether the apparent rise in population resulted in similar pressure elsewhere in Anatolia or throughout the empire toward the end of the century remains a question. Nevertheless, this study has also pointed out that the Celali rebellions and widespread terror in the Anatolian countryside were closely related to the demographic growth of the 16th century

    Volumetric evaluation of temporal bone structures in the cases with bilateral tinnitus: clinical and morphometrical study

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    Background: Tinnitus is the recognition of sound in the absence of any external auditory stimulus to the noise of ringing in the ears. Middle ear aeration carries important role for ossicular coupling and normal hearing. There is restricted morphometric data on the cases with bilateral tinnitus. Materials and methods: In this study we evaluated hearing findings of 18 cases with subjective nonpulsatile bilateral tinnitus and also morphometry and volumetry of temporal bone substructures on the computed tomography images using stereological method compared with the gender and age matched 12 healthy subjects. Duration of tinnitus, exposing acoustic trauma or/and high level noise levels, evaluation of middle ear volume, jugular bulb levels, distances between jugular bulb and both oval window and middle ear were evaluated. Results: Both males and females with tinnitus showed worse hearing thresholds through bone and air conductions than healthy subjects but it was not statistically significant. Pure tone thresholds through bone and air conductions were not statistically different in both sexes with bilateral tinnitus. Right middle ear volume of the cases with bilateral tinnitus was mean 5.57 cm3 for males and 5.64 cm3 for females; and also the left middle ear volume of the cases with bilateral tinnitus was mean 5.87 cm3 for males and 5.65 cm3 for females. There were no significant differences between the cases with bilateral tinnitus and the control subjects according to the side of the body. < strong > Conclusions: The data on the hearing findings and morphometrical evaluation of the cases with bilateral tinnitus may be important for anatomists and clinicians. (Folia Morphol 2018; 77, 1: 57–64)

    Effect of simulated gastric acid on aesthetical restorative CAD-CAM materials' microhardness and flexural strength

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    Background: Gastric acid, which is among erosive substances, gradually rises to the mouth in individuals with reflux and bulimia nervosa disorders, and this causes various effects on dental restorations. Aim: The objective of this study is in vitro investigation of gastric acid's effect on flexural strength and hardness on aesthetic restorative computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: For this study, four materials have been used, namely Enamic (Vita), Superfect Zir (Aidite) Zirconia, IPS e.max CAD (Ivoclar Vivadent), and Mark II (Vita). From these four different materials, 24 samples with 14 × 4 × 1 dimensions in rectangular prism form are used, which makes a total of 96 samples. One group was separated as the control group, while the rest was allowed to wait at 37°C, 5 ml gastric acid for 96 hours. Hardness value and flexural strengths were measured as pre-exposure and post-exposure to gastric acid. Results: There is a statistically significant difference between the groups in terms of the amount of decrease in the mean hardness after exposure to gastric acid compared to pre-exposure values (p: 0,000; P 0.05). There is a statistically significant difference between the groups in terms of the average flexural strength after exposure to the acid. Conclusions: According to the data obtained, it was concluded that exposure to gastric acid affects the hardness and flexural strength properties of dental restorative ceramic materials

    Metadata-based modeling of information resources on the web

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    This paper deals with the problem of modeling Web information resources using expert knowledge and personalized user information for improved Web searching capabilities. We propose a "Web information space" model, which is composed of Web-based information resources (HTML/XML [Hypertext Markup Language/Extensible Markup Language] documents on the Web), expert advice repositories (domain-expert-specified meta-data for information resources), and personalized information about users (captured as user profiles that indicates users' preferences about experts as well as users' knowledge about topics). Expert advice, the heart of the Web information space model, is specified using topics and relationships among topics (called metalinks), along the lines of the recently proposed topic maps. Topics and metalinks constitute metadata that describe the contents of the underlying HTML/XML Web resources. The metadata specification process is semiautomated, and it exploits XML DTDs (Document Type Definition) to allow domain-expert guided mapping of DTD elements to topics and metalinks. The expert advice is stored in an object-relational database management systems (DBMS). To demonstrate the practicality and usability of the proposed Web information space model, we created a prototype expert advice repository of more than one million topics/metalinks for DBLP (Database and Logic Programming) Bibliography data set. We also present a query interface that provides sophisticated querying facilities for DBLP Bibliography resources using the expert advice repository

    The two states of Sgr A* in the near-infrared: bright episodic flares on top of low-level continuous variability

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    In this paper we examine properties of the variable source Sgr A* in the near-infrared (NIR) using a very extensive Ks-band data set from NACO/VLT observations taken 2004 to 2009. We investigate the variability of Sgr A* with two different photometric methods and analyze its flux distribution. We find Sgr A* is continuously emitting and continuously variable in the near-infrared, with some variability occurring on timescales as long as weeks. The flux distribution can be described by a lognormal distribution at low intrinsic fluxes (<~5 mJy, dereddened with A_{Ks}=2.5). The lognormal distribution has a median flux of approximately 1.1 mJy, but above 5 mJy the flux distribution is significantly flatter (high flux events are more common) than expected for the extrapolation of the lognormal distribution to high fluxes. We make a general identification of the low level emission above 5 mJy as flaring emission and of the low level emission as the quiescent state. We also report here the brightest Ks-band flare ever observed (from August 5th, 2008) which reached an intrinsic Ks-band flux of 27.5 mJy (m_{Ks}=13.5). This flare was a factor 27 increase over the median flux of Sgr A*, close to double the brightness of the star S2, and 40% brighter than the next brightest flare ever observed from Sgr~A*.Comment: 14 pages, 6 figures, accepted for publication in Ap

    The HypHI project: Hypernuclear spectroscopy with stable heavy ion beams and rare isotope beams at GSI and FAIR

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    The HypHI collaboration aims to perform a precise hypernuclear spectroscopy with stable heavy ion beams and rare isotope beams at GSI and fAIR in order to study hypernuclei at extreme isospin, especially neutron rich hypernuclei to look insight hyperon-nucleon interactions in the neutron rich medium, and hypernuclear magnetic moments to investigate baryon properties in the nuclei. We are currently preparing for the first experiment with 6^6Li and 12^{12}C beams at 2 AGeV to demonstrate the feasibility of a precise hypernuclear spectroscopy by identifying Λ3^{3}_{\Lambda}H, Λ4^{4}_{\Lambda}H and Λ5^{5}_{\Lambda}He. The first physics experiment on these hypernuclei is planned for 2009. In the present document, an overview of the HypHI project and the details of this first experiment will be discussed.Comment: 5 pages, 2 figures, French-Japanese symposium 2008, Paris (France

    Modelling the black hole silhouette in Sgr A* with ion tori

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    We calculate the "observed at infinity" image and spectrum of the accretion structure in Sgr A*, by modelling it as an optically thin, constant angular momentum ion torus in hydrodynamic equilibrium. The physics we consider includes a two-temperature plasma, a toroidal magnetic field, as well as radiative cooling by bremsstrahlung, synchrotron and inverse Compton processes. Our relativistic model has the virtue of being fully analytic and very simple, depending only on eight tunable parameters: the black hole spin and the inclination of the spin axis to our line of sight, the torus angular momentum, the polytropic index, the magnetic to total pressure ratio, the central values of density and electron temperature and the ratio of electron to ion temperatures. The observed image and spectrum are calculated numerically using the ray-tracing code GYOTO. Our results demonstrate that the ion torus model is able to account for the main features of the accretion structure surrounding Sgr A*.Comment: 11 pages, 10 figures, submitted to A &

    Exclusive electroproduction of K+ Lambda and K+ Sigma^0 final states at Q^2 = 0.030-0.055 (GeV/c)^2

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    Cross section measurements of the exclusive p(e,e'K+)Lambda,Sigma^0 electroproduction reactions have been performed at the Mainz Microtron MAMI in the A1 spectrometer facility using for the first time the Kaos spectrometer for kaon detection. These processes were studied in a kinematical region not covered by any previous experiment. The nucleon was probed in its third resonance region with virtual photons of low four-momenta, Q^2= 0.030-0.055 (GeV/c)^2. The MAMI data indicate a smooth transition in Q^2 from photoproduction to electroproduction cross sections. Comparison with predictions of effective Lagrangian models based on the isobar approach reveal that strong longitudinal couplings of the virtual photon to the N* resonances can be excluded from these models.Comment: 16 pages, 7 figure

    Massive binary black holes in galactic nuclei and their path to coalescence

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    Massive binary black holes form at the centre of galaxies that experience a merger episode. They are expected to coalesce into a larger black hole, following the emission of gravitational waves. Coalescing massive binary black holes are among the loudest sources of gravitational waves in the Universe, and the detection of these events is at the frontier of contemporary astrophysics. Understanding the black hole binary formation path and dynamics in galaxy mergers is therefore mandatory. A key question poses: during a merger, will the black holes descend over time on closer orbits, form a Keplerian binary and coalesce shortly after? Here we review progress on the fate of black holes in both major and minor mergers of galaxies, either gas-free or gas-rich, in smooth and clumpy circum-nuclear discs after a galactic merger, and in circum-binary discs present on the smallest scales inside the relic nucleus.Comment: Accepted for publication in Space Science Reviews. To appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher

    Nuclear matter at high density: Phase transitions, multiquark states, and supernova outbursts

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    Phase transition from hadronic matter to quark-gluon matter is discussed for various regimes of temperature and baryon number density. For small and medium densities, the phase transition is accurately described in the framework of the Field Correlation Method, whereas at high density predictions are less certain and leave room for the phenomenological models. We study formation of multiquark states (MQS) at zero temperature and high density. Relevant MQS components of the nuclear matter can be described using a previously developed formalism of the quark compound bags (QCB). Partial-wave analysis of nucleon-nucleon scattering indicates the existence of 6QS which manifest themselves as poles of PP-matrix. In the framework of the QCB model, we formulate a self-consistent system of coupled equations for the nucleon and 6QS propagators in nuclear matter and the G-matrix. The approach provides a link between high-density nuclear matter with the MQS components and the cumulative effect observed in reactions on the nuclei, which requires the admixture of MQS in the wave functions of nuclei kinematically. 6QS determine the natural scale of the density for a possible phase transition into the MQS phase of nuclear matter. Such a phase transition can lead to dynamic instability of newly born protoneutron stars and dramatically affect the dynamics of supernovae. Numerical simulations show that the phase transition may be a good remedy for the triggering supernova explosions in the spherically symmetric supernova models. A specific signature of the phase transition is an additional neutrino peak in the neutrino light curve. For a Galactic core-collapse supernova, such a peak could be resolved by the present neutrino detectors. The possibility of extracting the parameters of the phase of transition from observation of the neutrino signal is discussed also.Comment: 57 pages, 22 figures, 7 tables; RevTeX 4; submitted to Phys. Atom. Nuc
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