327 research outputs found
Extensive population synthesis of isolated neutron stars with field decay
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 --
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 and . 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 ( 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
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 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
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
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)
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
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
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
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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