The Bologna submillisecond pulsar survey

Since the discovery of the original millisecond pulsar, no pulsars with a shorter spin period (P<1.56 ms) were found. However, according to the most popular equations of state, the theoretical limiting spin period of a neutron star can be much shorter. On the other hand, most of the large scale searches for millisecond pulsars carried out so far were strongly biased against the detection of ultrashort periodicities. In this paper we describe a new large scale pulsar survey with a minimum detectable period much shorter than previous searches.Comment: 4 pages, two included figures, to be published in proceedings of "Pulsar Astronomy -- 2000 and Beyond", ASP Conf. Se

CMB temperature anisotropies from third order gravitational perturbations

In this paper we present a complete computation of the Cosmic Microwave Background (CMB) anisotropies up to third order from gravitational perturbations accounting for scalar, vector and tensor perturbations. We then specify our results to the large scale limit, providing the evolution of the gravitational potentials in a flat universe filled with matter and cosmological constant which characterizes the Integrated Sachs-Wolfe effect. As a byproduct in the large scale approximation we are able to give non-perturbative solutions for the photon geodesic equations. Our results are the first step to provide a complete theoretical prediction for cubic non-linearities which are particularly relevant for characterizing the level of non-Gaussianity in the CMB through the detection of the four-point angular connected correlation function (trispectrum). For this purpose we also allow for generic initial conditions due to primordial non-Gaussianity.Comment: 19 pages, LateX file; typos corrected; some corrections made and several consistency checks performed regarding Eqs.(2.18); (2.28)-(2.29) and Eqs.(3.8)-(3.24) and Eq.(4.2). Version accepted for publication in JCA

Effect of matrix parameters on mesoporous matrix based quantum computation

We present a solid state implementation of quantum computation, which improves previously proposed optically driven schemes. Our proposal is based on vertical arrays of quantum dots embedded in a mesoporous material which can be fabricated with present technology. We study the feasibility of performing quantum computation with different mesoporous matrices. We analyse which matrix materials ensure that each individual stack of quantum dots can be considered isolated from the rest of the ensemble-a key requirement of our scheme. This requirement is satisfied for all matrix materials for feasible structure parameters and GaN/AlN based quantum dots. We also show that one dimensional ensembles substantially improve performances, even of CdSe/CdS based quantum dots

Timing the millisecond pulsars in 47 Tucanae

In the last 10 years 20 millisecond pulsars have been discovered in the globular cluster 47 Tucanae. Hitherto, only 3 of these had published timing solutions. Here we improve upon these 3 and present 12 new solutions. These measurements can be used to determine a variety of physical properties of the pulsars and of the cluster. The 15 pulsars have positions determined with typical uncertianties of only a few milliarcsec and they are all located within 1.2 arcmin of the cluster centre. We have also measured the proper motions of 5 of the pulsars, which are consistent with the proper motion of 47 Tuc based on Hipparcos data. The period derivatives measured for many of the pulsars are dominated by the dynamical effects of the cluster gravitational field, and are used to constrain the surface mass density of the cluster. All pulsars have characteristic ages T > 170 Myr and magnetic fields B < 2.4e9 Gauss, and the average T > 1 Gyr. We have measured the rate of advance of periastron for the binary pulsar J0024-7204H, implying a total system mass 1.4+-0.8 solar masses.Comment: 17 pages, 11 included figures, accepted for publication in MNRA

Discovery of Two High-Magnetic-Field Radio Pulsars

We report the discovery of two young isolated radio pulsars with very high inferred magnetic fields. PSR J1119-6127 has period P = 0.407 s, and the largest period derivative known among radio pulsars, Pdot = 4.0e-12. Under standard assumptions these parameters imply a characteristic spin-down age of only tau = 1.6 kyr and a surface dipole magnetic field strength of B = 4.1e13 G. We have measured a stationary period-second-derivative for this pulsar, resulting in a braking index of n = 2.91+-0.05. We have also observed a glitch in the rotation of the pulsar, with fractional period change Delta_P/P = -4.4e-9. Archival radio imaging data suggest the presence of a previously uncataloged supernova remnant centered on the pulsar. The second pulsar, PSR J1814-1744, has P = 3.975 s and Pdot = 7.4e-13. These parameters imply tau = 85 kyr, and B = 5.5e13 G, the largest of any known radio pulsar. Both PSR J1119-6127 and PSR J1814-1744 show apparently normal radio emission in a regime of magnetic field strength where some models predict that no emission should occur. Also, PSR J1814-1744 has spin parameters similar to the anomalous X-ray pulsar (AXP) 1E 2259+586, but shows no discernible X-ray emission. If AXPs are isolated, high magnetic field neutron stars (``magnetars''), these results suggest that their unusual attributes are unlikely to be merely a consequence of their very high inferred magnetic fields.Comment: 7 pages, 3 embedded EPS figures, to be published in Ap

Assessing physical activity in daily life, exercise, and sedentary behavior among Japanese moving to westernized environment: A cross-sectional study of Japanese migrants at an urban primary care center in Pittsburgh

Background: Noncommunicable chronic diseases (NCDs) are global public health issues. Physical activity, exercise and sedentary behavior are important lifestyle factors to determine risk of NCDs. Immigrant studies have shown higher risk of developing NCDs among immigrants. Less physical activity among Japanese immigrants to westernized environment was also documented. However, little is known about detailed physical activity, exercise and sedentary behavior among Japanese residing in westernized environment. This cross-sectional study was conducted to analyze physical activity in daily life, exercise, and sedentary behavior among Japanese in westernized environment and then to compare the results to native Japanese in Japan. Methods. Japanese adults in Pittsburgh who were registered at an urban primary care clinic were surveyed in terms of physical activity in daily life, exercise, and sedentary behavior. The results were compared to age- and gender-matched Japanese averages from the national data (Japanese National Health and Nutrition Survey, J-NHANS). Results: Of 97 identified for inclusion, all responded. Japanese in Pittsburgh did not engage physical activity in daily life as compared to J-NHANS results (p <.001 for both genders). Only 45.0% and 26.3% of Japanese men and women in Pittsburgh, respectively, reached the recommended level of exercise. The prevalence of regularly engaging moderate or vigorous level of exercise was significantly lower among Japanese in Pittsburgh than age- and gender-matched J-NHANS results. The prevalence of 2 hours or more per week of exercise at moderate or higher level among Japanese men and women in Pittsburgh were lower than J-NHANS results. Women in Pittsburgh showed significantly less sedentary time as compared to J-NHANS results, while men only showed significantly less sitting/lying time during weekend. We found no association between sedentary time (time in sitting/lying and TV/computer) and exercise time during weekday or weekend in the target population. Conclusions: Although Japanese in Pittsburgh showed lower prevalence of sedentary behavior, prevalence of regular physical activity and exercise were less than prevalence of native Japanese. © 2014 Hirooka et al.; licensee BioMed Central Ltd

Probing the Equation of State of Ultradense Matter with a Submillisecond Pulsar Search Experiment

Current ideas about the equation of state for the ultradense matter constituting neutron stars provide models with a range of neutron star radii for a given mass. This implies different estimates for the maximum angular velocity that such an object could attain. The fastest and the slowest angular velocity differ by a significant amount, depending on the equation of state adopted. In particular, the identification of a submillisecond pulsar would allow us to constrain the equation of state of dense matter. In this paper, we discuss a possible evolutionary scenario resulting in a submillisecond pulsar, taking into account current ideas about the evolution of the magnetic field of neutron stars. Pulsar luminosities and lifetimes in the submillisecond period range, derived on the basis of phenomenological considerations, suggest that the effort of searching for such an object would be worthwhile. All the pulsar searches conducted up to now have been prevented by instrumental selection effects from probing the submillisecond range. We discuss the feasibility of a submillisecond pulsar search experiment in the context of current hardware and software capabilities