Evidence for Free Precession in the Pulsar B1642-03

We present an analysis of the timing data of the pulsar B1642-03, collected over a span of 30 years between 1969 and 1999. During this interval, the timing residuals exhibit cyclical changes with amplitude varying from 15 ms to 80 ms and spacing of maxima varying from 3 years to 7 years. Interpretation of these observed cyclical changes in terms of free precession suggests a wobble angle of about 0.8 degrees.Comment: 9 pages, 5 figures. Accepted for publication in Ap

The Crustal Rigidity of a Neutron Star, and Implications for PSR 1828-11 and other Precession Candidates

We calculate the crustal rigidity parameter, b, of a neutron star (NS), and show that b is a factor 40 smaller than the standard estimate due to Baym & Pines (1971). For a NS with a relaxed crust, the NS's free-precession frequency is directly proportional to b. We apply our result for b to PSR 1828-11, a 2.5 Hz pulsar that appears to be precessing with period 511 d. Assuming this 511-d period is set by crustal rigidity, we show that this NS's crust is not relaxed, and that its reference spin (roughly, the spin for which the crust is most relaxed) is 40 Hz, and that the average spindown strain in the crust is 5 \times 10^{-5}. We also briefly describe the implications of our b calculation for other well-known precession candidates.Comment: 44 pages, 10 figures, submitted to Ap

Avalanche dynamics of radio pulsar glitches

We test statistically the hypothesis that radio pulsar glitches result from an avalanche process, in which angular momentum is transferred erratically from the flywheel-like superfluid in the star to the slowly decelerating, solid crust via spatially connected chains of local, impulsive, threshold-activated events, so that the system fluctuates around a self-organised critical state. Analysis of the glitch population (currently 285 events from 101 pulsars) demonstrates that the size distribution in individual pulsars is consistent with being scale invariant, as expected for an avalanche process. The waiting-time distribution is consistent with being exponential in seven out of nine pulsars where it can be measured reliably, after adjusting for observational limits on the minimum waiting time, as for a constant-rate Poisson process. PSR J0537$-$6910 and PSR J0835$-$4510 are the exceptions; their waiting-time distributions show evidence of quasiperiodicity. In each object, stationarity requires that the rate $\lambda$ equals $- \epsilon \dot{\nu} /$, where $\dot{\nu}$ is the angular acceleration of the crust, $$ is the mean glitch size, and $\epsilon\dot{\nu}$ is the relative angular acceleration of the crust and superfluid. There is no evidence that $\lambda$ changes monotonically with spin-down age. The rate distribution itself is fitted reasonably well by an exponential for $\lambda \geq 0.25 {\rm yr^{-1}}$. For $\lambda < 0.25 {\rm yr^{-1}}$, its exact form is unknown; the exponential overestimates the number of glitching pulsars observed at low $\lambda$, where the limited total observation time exercises a selection bias.Comment: Accepted for publication in the Astrophysical Journa

Synthesis of Powder Materials with Particles Encapsulated into Carbon Containing Nanostructural Films

Particles of a complex structure: a quartz nucleus encapsulated into metalpolymer carbon containing nanosize film of the type “cluspol” have been obtained as a result of mechanochemical treatment of quartz with carbon containing organic compounds. Electronmicroscopic investigations show the diversity of morphological forms and nanostructural carbon formations on the surface of modified quartz particles. Depending on the regimes of mechanochemical treatment, the obtained materials are characterized by considerable changes in electromagnetic properties. The choice of carbon containing modifiers provided a highly active physico-chemical state of quartz of a prolonged action

Phase and Intensity Distributions of Individual Pulses of PSR B0950+08

The distribution of the intensities of individual pulses of PSR B0950+08 as a function of the longitudes at which they appear is analyzed. The flux density of the pulsar at 111 MHz varies strongly from day to day (by up to a factor of 13) due to the passage of the radiation through the interstellar plasma (interstellar scintillation). The intensities of individual pulses can exceed the amplitude of the mean pulse profile, obtained by accumulating 770 pulses, by more than an order of magnitude. The intensity distribution along the mean profile is very different for weak and strong pulses. The differential distribution function for the intensities is a power law with index n = -1.1 +- 0.06 up to peak flux densities for individual pulses of the order of 160 Jy

The Formation of Morphological Structures of Carbon and Oxide Silicon Nanoparticles

The concept morphostructure formations nanosized individuals on the basis of carbon and quartz is offered. Under offered circuit in “the first stage” substances are generated by atoms – “elementary individuals”. They - form “simple morphostructures”, for example, fullerenes, film and a one-wall carbon tube. They have, at the best the two-dimensional structural order. The second stage of growth morphostructures is connected to formation of more complex of “elementary particles” on the basis of the approximated rounded molecules. They - form “simple morphostructures”, for example, fullerenes, film and carbon tube also. The third stage - clusters. Clusters, similarly to atoms and molecules, can form cyclic formations (oligomer/polymers), crystals and can enter structure of the mixed constructions of a layer. They can form also simple morphostructures, for example, fullerenes, film and carbon tube. The fourth stage - compact formations of polymer and so on

Quartz Particles Electron-Microscopic Investigations Modified by Mechanochemical Processing

There were taken and analyzed electron-microscopic images of quartz particles after mechanochemical processing in mill-activator with different organic modifiers. It was stated that quartz surface suffers serious changes the peculiarities of which are defined by used modifiers. Quartz particle has a complex flaky morphology. Friable surface layers represent as carbonic element-organic formations with ferrous additives. The change of particle's surface layers are responsible to modified quartz physicochemical properties transfer

Elongated Wire-Like Zinc Oxide Nanostructures Synthesized from Metallic Zinc

Elongated wire-like Zinc oxide, nanocombs and nanocrystals have been successfully synthesized on the silicon substrate from the metallic zinc as a starting material. The annealing temperature was as low as 450 ºC in argon atmosphere mixed with about 3% oxygen. Structural analysis using the X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) showed that the existence of two phases; nanowires and crystalline form. Moreover some nanoparticles aggregates were noticed to be attached in the bulk to the sides of the ZnO nanocrystals and sometimes these aggregate attached to the Zinc oxide hexagonal crystal and grow to form nanowire at different angles. Scanning electron microscopy (SEM) investigations for the zinc oxide nanostructure on the silicon substrate showed the formation of the nanocrystals in the gas flow direction and at the low energy sites over the silicon substrate. Photoluminescence (PL) measurements, performed at the room temperature, showed the existence of two basic emissions: narrow ultraviolet (UV) emission at 398 nm which attributed to the near band edge emission of the wide band gap and a very wide, more intensive, green emission at 471 nm corresponds to the crystal defects such as vacancies, interstitial sites in ZnO

Новые аспекты в механизмах ишемического и реперфузионного повреждения миокарда

Introduction. The present article, in which a contemporary analysis of the literature on the pathophysiology of ischemic and reperfusion injury (IRI) of the myocardium is presented, focuses on the possible role played by of the calpain system and oxidative stress. Several process development options were proposed, including cytosolic and mitochondrial Ca2+ overload, reactive oxygen stress release, acute inflammatory response and metabolic degradation. The combined effect of all of the above factors produces irreversible ischemic and reperfused damage of cardiomyocytes.Materials and methods. The role of the calpain system in the creation of myocardial IRI was experimentally investigated. It was found that active calpain substrates play a significant role in the processes of cell cycle, apoptosis and differentiation, adversely affecting cardiomyocyte functionality. The calpain system is part of an integrated proteolytic system that is critical to the relationship between the structure and function of the cardiac sarcomere. Uncontrolled activation of calpain is indicated in the pathophysiology of many cardiovascular disorders. As shown by research, inhibitor calpain reduces the size of the zone of infarction following ischemia reperfusion and thus lessens the risk of “stunning” the myocardium. As is known, a consequence of IRI is acute myocardial infarction (AMI), which is a central factor in cardiovascular disease (CVD) and is one of the primary causes of mortality. Understanding the exact pathophysiological mechanisms remains an urgent problem for clinical physicians. To date, the mechanisms of IRI are not fully known, which creates certain difficulties in further treatment and prevention tactics. In addition, myocardial IRI is also an important issue for pathoanatomical service, since sudden coronary death can occur despite timely reperfusion therapy following AMI.Conclusion. The development of strategies for creating conditions that limit the degree of damage to myocardial tissues significantly increases the ability of the heart to withstand ischemic damage.Введение. В статье представлен современный анализ литературы относительно патофизиологии ишемического и реперфузионного повреждения (ИРП) миокарда, который сосредоточен на возможной роли кальпаиновой системы и окислительного стресса. Были предложены несколько вариантов развития процессов, включая цитозольный и митохондриальную Ca2+-перегрузку, выпуск реактивного кислородного стресса, острую воспалительную реакцию и ухудшение метаболизма. Совместное воздействие всего перечисленного производит необратимое ишемическое и реперфузированное повреждение кардиомиоцитов.Материалы и методы. Была экспериментально исследована роль кальпаиновой системы в создании миокардиального ИРП. Обнаружено, что субстраты активного кальпаина играют весомую роль в процессах клеточного цикла, апоптоза и дифференцирования, они отрицательно сказываются на функциях кардиомиоцитов. Кальпаиновая система — часть интегрированной протеолитической системы, которая является критической в отношениях между структурой и функцией кардиального саркомера. Бесконтрольная активация кальпаина вовлекает в патофизиологию множество сердечно-сосудистых нарушений. Ингибитор кальпаина, как показывали исследования, уменьшает риск «оглушения» миокарда и размер зоны инфаркта после ишемии реперфузии. Как известно, следствием ИРП является острый инфаркт миокарда (ОИМ), который занимает ведущую роль в сердечно-сосудистых заболеваниях (ССЗ), а также является одной из основных причин смертности населения. Понимание точных патофизиологических механизмов остается актуальной проблемой для клинических врачей. На сегодняшний день механизмы ИРП не полностью известны, что создает определенные трудности в дальнейшей тактике лечения и профилактике. Кроме того, миокардиальное ИРП является важным вопросом и для патологоанатомической службы, так как внезапная коронарная смерть может произойти несмотря на своевременную реперфузионную терапию после ОИМ.Заключение. Развитие стратегий по созданию условий, ограничивающих степень повреждения миокардиальных тканей, заметно увеличивает способность сердца выдерживать ишемическое повреждение