A Pulsational Model for the Orthogonal Polarization Modes in Radio Pulsars

In an earlier paper, we introduced a model for pulsars in which non-radial oscillations of high spherical degree (\el) aligned to the magnetic axis of a spinning neutron star were able to reproduce subpulses like those observed in single-pulse measurements of pulsar intensity. The model did not address polarization, which is an integral part of pulsar emission. Observations show that many pulsars emit radio waves that appear to be the superposition of two linearly polarized emission modes with orthogonal polarization angles. In this paper, we extend our model to incorporate linear polarization. As before, we propose that pulsational displacements of stellar material modulate the pulsar emission, but now we apply this modulation to a linearly-polarized mode of emission, as might be produced by curvature radiation. We further introduce a second polarization mode, orthogonal to the first, that is modulated by pulsational velocities. We combine these modes in superposition to model the observed Stokes parameters in radio pulsars.Comment: 19 pages, 4 figures accepted Ap

On the Nature of Precursors in the Radio Pulsar Profiles

In the average profiles of several radio pulsars, the main pulse is accompanied by the preceding component. This so called precursor is known for its distinctive polarization, spectral, and fluctuation properties. Recent single-pulse observations hint that the sporadic activity at the extreme leading edge of the pulse may be prevalent in pulsars. We for the first time propose a physical mechanism of this phenomenon. It is based on the induced scattering of the main pulse radiation into the background. We show that the scattered component is directed approximately along the ambient magnetic field and, because of rotational aberration in the scattering region, appears in the pulse profile as a precursor to the main pulse. Our model naturally explains high linear polarization of the precursor emission, its spectral and fluctuation peculiarities as well as suggests a specific connection between the precursor and the main pulse at widely spaced frequencies. This is believed to stimulate multifrequency single-pulse studies of intensity modulation in different pulsars.Comment: 5 pages, no figures. Accepted for publication in MNRAS Letter

How are risk ratios reported in orthopaedic surgery journals? A descriptive study of formats used to report absolute risks

The numerical format in which risks are communicated can affect risk comprehension and perceptions of medical professionals. We investigated what numerical formats are used to report absolute risks in empirical articles, estimated the frequency of biasing formats and rated the quality of figures used to display the risks. Descriptive study of reporting practices. We randomly sampled articles published in seven leading orthopaedic surgery journals during a period of 13 years. From these, we selected articles that reported group comparisons on a binary outcome (eg, revision rates in two groups) and recorded the numerical format used to communicate the absolute risks in the results section. The quality of figures was assessed according to published guidelines for transparent visual aids design. Prevalence of information formats and quality of figures. The final sample consisted of 507 articles, of which 14% reported level 1 evidence, 13% level 2 and 73% level 3 or lower. The majority of articles compared groups of different sizes (90%), reported both raw numbers and percentages (64%) and did not report the group sizes alongside (50%). Fifteen per cent of articles used two formats identified as biasing: only raw numbers (8%, '90 patients vs 100 patients') or raw numbers reported alongside different group sizes (7%, '90 out of 340 patients vs 100 out of 490 patients'). The prevalence of these formats decreased in more recent publications. Figures (n=79) had on average two faults that could distort comprehension, and the majority were rated as biasing. Authors use a variety of formats to report absolute risks in scientific articles and are likely not aware of how some formats and graph design features can distort comprehension. Biases can be reduced if journals adopt guidelines for transparent risk communication but more research is needed into the effects of different formats

Interpretation of the Low-Frequency Peculiarities in the Radio Profile Structure of the Crab Pulsar

The theory of magnetized induced scattering off relativistic gyrating particles is developed. It is directly applicable to the magnetosphere of a pulsar, in which case the particles acquire gyration energies as a result of resonant absorption of radio emission. In the course of the radio beam scattering into background the scattered radiation concentrates along the ambient magnetic field. The scattering from different harmonics of the particle gyrofrequency takes place at different characteristic altitudes in the magnetosphere and, because of the rotational effect, gives rise to different components in the pulse profile. It is demonstrated that the induced scattering from the first harmonic into the state under the resonance can account for the so-called low-frequency component in the radio profile of the Crab pulsar. The precursor component is believed to result from the induced scattering between the two states well below the resonance. It is shown that these ideas are strongly supported by the polarization data observed. Based on an analysis of the fluctuation behaviour of the scattering efficiencies, the transient components of a similar nature are predicted for other pulsars.Comment: 9 pages, no figures. Accepted for publication in MNRA

Physics of Interpulse Emission in Radio Pulsars

The magnetized induced Compton scattering off the particles of the ultrarelativistic electron-positron plasma of pulsar is considered. The main attention is paid to the transverse regime of the scattering, which holds in a moderately strong magnetic field. We specifically examine the problem on induced transverse scattering of the radio beam into the background, which takes place in the open field line tube of a pulsar. In this case, the radiation is predominantly scattered backwards and the scattered component may grow considerably. Based on this effect, we for the first time suggest a physical explanation of the interpulse emission observed in the profiles of some pulsars. Our model can naturally account for the peculiar spectral and polarization properties of the interpulses. Furthermore, it implies a specific connection of the interpulse to the main pulse, which may reveal itself in the consistent intensity fluctuations of the components at different timescales. Diverse observational manifestations of this connection, including the moding behavior of PSR B1822-09, the peculiar temporal and frequency structure of the giant interpulses in the Crab pulsar, and the intrinsic phase correspondence of the subpulse patterns in the main pulse and the interpulse of PSR B1702-19, are discussed in detail. It is also argued that the pulse-to-pulse fluctuations of the scattering efficiency may lead to strong variability of the interpulse, which is yet to be studied observationally. In particular, some pulsars may exhibit transient interpulses, i.e. the scattered component may be detectable only occasionally.Comment: 28 pages, 2 figures. Accepted for publication in Ap

Gaussian fluctuations in an ideal bose-gas -- a simple model

Based on the canonical ensemble, we suggested the simple scheme for taking into account Gaussian fluctuations in a finite system of ideal boson gas. Within framework of scheme we investigated the influence of fluctuations on the particle distribution in Bose -gas for two cases - with taking into account the number of particles in the ground state and without this assumption. The temperature and fluctuation parameter dependences of the modified Bose- Einstein distribution have been determined. Also the dependence of the condensation temperature on the fluctuation distribution parameter has been obtained.Comment: arXiv admin note: text overlap with arXiv:cond-mat/040859

Vibrational spectra and internal rotation of 1,2-diphenylethane

Internal rotation of 1,2-diphenylethane has been studied. Infrared absorption spectra of 1,2-diphenylethane in crystalline phase, liquid and solutions at various temperatures have been investigated. Assignment of the peaks to trans and gauche conformations was performed. Band fitting and factor analysis were applied to conformationally sensitive regions of the spectra. Enthalpy and entropy differences of the conformers were determined and discussed in frames of the reaction field model

Vibrational spectra and molecular dynamics of 1,2-di-(p-XC6H4)ethanes (X=Br, NO2)

Infrared absorption spectra and internal rotation of 1,2-di-(p-XC6H4)ethanes (X=Br, NO2) have been investigated. The magnitude of the barrier to internal rotation of 1,2-di-(p-bromophenyl)ethane has been estimated. The analysis of IR spectra of 1,2-di-(p-nitrophenyl)ethane in liquid and crystalline states and its solutions has allowed to make conclusion about the presence of the dynamic equilibrium of the trans and gauche conformations. The division of the absorption bands into components and the factor analysis have been used in the interpretation of the IR spectra. The enthalpy and entropy differences of the trans and gauche conformations have been determined and besides these values are discovered to be anomalous large as compared with ones which are usually observed for the conformational equilibria

The influence of intermolecular interactions on the internal dynamics of para-substituted 1,2-diphenylethanes

The IR absorption spectra and internal rotation of 1,2-di(para-XC 6H4)ethanes (X = H, Br, NO2) were studied in the crystalline and liquid phases and solutions at various temperatures. The thermodynamic parameters of conformational equilibria were determined. The concentrations of the conformers were found by factor analysis techniques. The trans and gauche conformers were studied by ab initio quantum-chemical calculations. The obtained differences of the Gibbs energies and entropies of the conformers were considered in terms of the reaction field model. The presence of the compensation effect in the thermodynamics of conformational transitions was substantiated

The role of entrepreneurship in the economic development of the region

In the article analyzed the entrepreneurial activities on the territory of the Republic of Bashkortostan, as well as the tendencies of development of small and medium businesses under favourable business climate. The methodology is the analysis of dynamics of development of business entities based on statistical data. It is noted that the formation and development of entrepreneurship in the regions of the Russian Federation is a complex socio-economic phenomenon arising due to deep transformations in the field of sociocultural relations, because changes in the latter interacts with all the key parties, the social life of the people: moral and ethical norms, mentality, spiritual and material values, social norms and economic behavior. Modern entrepreneurship as a factor of economic development of the region needs continued support from the state with the knowledge of essential managerial and regulatory functions of the legislative and Executive power structures in the economy and society. This fact is explainable by the fact that the entity is a specified function consists of continuous improvement activities of power structures, improvement of transmission channels and introduction of achievements of scientific-technical progress in all stages of the multifaceted and complex structure of social production, providing an invaluable contribution of managerial labor in the common cause of improving the efficiency of the economy. Conclusion: in current economic conditions, the region assigns a significant role to subjects of small and medium businesses, which, thanks to its maneuverability, more adapted to the constantly changing market conditions. Applying comprehensive and systematic measures for the formation of a favorable environment, the Republican leadership promotes the competitive capacity of regional enterprises of small and medium business can compete with large companies