327 research outputs found

    Extensive population synthesis of isolated neutron stars with field decay

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    We perform population synthesis studies of different types of neutron stars taking into account the magnetic field decay. For the first time, we confront our results with observations using {\it simultaneously} the Log N -- Log S distribution for nearby isolated neutron stars, the Log N -- Log L distribution for magnetars, and the distribution of radio pulsars in the PP -- P˙\dot P diagram. We find that our theoretical model is consistent with all sets of data if the initial magnetic field distribution function follows a log-normal law with 13.25 \sim 13.25 and σlogB00.6\sigma_{\log B_0}\sim 0.6. The typical scenario includes about 10% of neutron stars born as magnetars, significant magnetic field decay during the first million years of a NS life. Evolutionary links between different subclasses may exist, although robust conclusions are not yet possible. We apply the obtained field distribution and the model of decay to study long-term evolution of neuton stars till the stage of accretion from the interstellar medium. It is shown that though the subsonic propeller stage can be relatively long, initially highly magnetized neutron stars (B0>1013B_0 > \sim 10^{13} G) reach the accretion regime within the Galactic lifetime if their kick velocities are not too large. The fact that in previous studies made >>10 years ago, such objects were not considered results in a slight increase of the Accretor fraction in comparison with earlier conclusions. Most of the neutron stars similar to the Magnificent seven are expected to become accreting from the interstellar medium after few billion years of their evolution. They are the main predecestors of accreting isolated neutron stars.Comment: 4 pages, conference "Astrophysics of Neutron Stars - 2010" in honor of M. Ali Alpar, Izmir, Turke

    Population synthesis of DA white dwarfs: constraints on soft X-ray spectra evolution

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    Extending the population synthesis method to isolated young cooling white dwarfs we are able to confront our model assumptions with observations made in ROSAT All-Sky Survey (Fleming et al., 1996). This allows us to check model parameters such as evolution of spectra and separation of heavy elements in DA WD envelopes. It seems like X-ray spectrum temperature of these objects is given by the formula T_{X-ray} = min(T_eff, T_max). We have obtained DA WD's birth rate and upper limit of the X-ray spectrum temperature: DA birth rate =0.61×1012= 0.61\times 10^{-12} in cubic parsec per year and T_max = 41000 K. These values are in good correspondence with values obtained by other authors (Liebert et al., 2004; Wolff et al., 1996). From this fact we also conclude that our population synthesis method is applicable to the population of close-by isolated cooling white dwarfs as well as to the population of the isolated cooling neutron stars.Comment: 4 pages, 3 figures, conference "European White Dwarf Workshop, 2010", Tubingen, German

    Population growth in discrete time: a renewal equation oriented survey

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    Traditionally, population models distinguish individuals on the basis of their current state. Given a distribution, a discrete time model then specifies (precisely in deterministic models, probabilistically in stochastic models) the population distribution at the next time point. The renewal equation alternative concentrates on newborn individuals and the model specifies the production of offspring as a function of age. This has two advantages: (i) as a rule, there are far fewer birth states than individual states in general, so the dimension is often low; (ii) it relates seamlessly to the next-generation matrix and the basic reproduction number. Here we start from the renewal equation for the births and use results of Feller and Thieme to characterise the asymptotic large time behaviour. Next we explicitly elaborate the relationship between the two bookkeeping schemes. This allows us to transfer the characterisation of the large time behaviour to traditional structured-population models

    Hyper-complex four-manifolds from the Tzitz\'eica equation

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    It is shown how solutions to the Tzitz\'eica equation can be used to construct a family of (pseudo) hyper-complex metrics in four dimensions.Comment: To be published in J.Math.Phy

    Diagnosis and treatment of muscle pain according to Tipaldos (literature review)

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    This review contents the information on the theory of the structure and mechanisms of damage to the body fascial system, proposed by American osteopath S. Tipaldos and named by him the Fascial Distortion Model (FDM), as well as on the original method of diagnosis and treatment of muscle pain syndromes associated with fascial damage (distortion). The author describes classifications of connective tissue and fascial structures, created by S.  Tipaldos, which are based on anatomical and functional features that determine the role of each type of fascia in compensating for various types of external influences. The conditions, mechanisms of formation and characteristics of six types of fascial lesions identified by S. Tipaldos are considered in detail: triggerband, herniated triggerpoint, continuum distortion, folding distortion, cylinder distortion, tectonic fixation. All elements of the fascial distortions diagnosis are discussed in detail, including the specification of complaints (characteristics of pain syndrome), anamnesis (history of the pain onset and its development) and an objective examination (the actual diagnostic techniques). At the same time, the special role of the patient’s description of his own painful sensations with the help of specific gestures and movements, called «body language», is emphasized. The principles and some methods of therapeutic effects used in FDM-therapy, indications and contraindications for the use of the considered manual techniques, possible side reactions that may occur during manipulation or after a session of FDMtherapy are presented. Particular attention is paid to  the evidence base of FDM therapy effectiveness in comparison with traditional methods of myofascial pain syndromes manual treatment: the results of controlled studies by foreign authors, confirming the new technique effectiveness in the treatment of certain muscle algic phenomena types, are considered

    Air ions induced aerosol sensing by eye-safe LIDAR

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    Low concentrations aerosols quantification is rather challenging for LIDAR instruments due to eye-safety restrictions so high energy pulses cannot be utilized to improve the sensitivity. Highly sensitive but eye-save LIDAR has been developed for the quantification of the water droplet aerosol which was induced by air ions. Few days sensing of aerosols in closed tunnel revealed a strong correlation between air optical transparency (LIDAR measurements) and concentrations of positive/negative ions (ion counter Sapphir 3-M). The correlation coefficient was observed to be almost unity for the air transparency signal and air ions unipolarity coefficient. High sensitivity of the water droplet aerosol quantification makes the developed eye-safe LIDAR a perspective instrument for space resolved measurements of the air ions distribution. Space and time resolved measurements of air ions exhalation can be a new instrument for tectonic activity study including new earthquake forecasting indicators search

    Pneumatic device of the preload and dynamic loads balancing to reduce the intensity of thermal processes in the metal cutting process

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    Improved reliability of the technological system "machine-tool-instrument-detail" is an important current task. Backlashes and insufficient stiffness of technological system lead to intensive wear of the cutting tool, increasing the heat in the cutting zone. Due to high temperature in the thin surface layers of the workpiece and tool thermal processes may occur which are similar to release and can cause the structural changes of the material. The current article presents the final design of the device which has been developed to reduce the intensity of thermal processes in metal cutting

    Caspase-8 binding to cardiolipin in giant unilamellar vesicles provides a functional docking platform for bid

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    Caspase-8 is involved in death receptor-mediated apoptosis in type II cells, the proapoptotic programme of which is triggered by truncated Bid. Indeed, caspase-8 and Bid are the known intermediates of this signalling pathway. Cardiolipin has been shown to provide an anchor and an essential activating platform for caspase-8 at the mitochondrial membrane surface. Destabilisation of this platform alters receptor-mediated apoptosis in diseases such as Barth Syndrome, which is characterised by the presence of immature cardiolipin which does not allow caspase-8 binding. We used a simplified in vitro system that mimics contact sites and/or cardiolipin-enriched microdomains at the outer mitochondrial surface in which the platform consisting of caspase-8, Bid and cardiolipin was reconstituted in giant unilamellar vesicles. We analysed these vesicles by flow cytometry and confirm previous results that demonstrate the requirement for intact mature cardiolipin for caspase-8 activation and Bid binding and cleavage. We also used confocal microscopy to visualise the rupture of the vesicles and their revesiculation at smaller sizes due to alteration of the curvature following caspase-8 and Bid binding. Biophysical approaches, including Laurdan fluorescence and rupture/tension measurements, were used to determine the ability of these three components (cardiolipin, caspase-8 and Bid) to fulfil the minimal requirements for the formation and function of the platform at the mitochondrial membrane. Our results shed light on the active functional role of cardiolipin, bridging the gap between death receptors and mitochondria
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