X-Rays from the Nearby Solitary Millisecond Pulsar PSR J0030+0451 - the Final ROSAT Observations

We report on X-ray observations of the solitary 4.8 ms pulsar PSR J0030+0451. The pulsar was one of the last targets observed in DEC-98 by the ROSAT PSPC. X-ray pulses are detected on a $4.5\sigma$ level and make the source the $11^{th}$ millisecond pulsar detected in the X-ray domain. The pulsed fraction is found to be $69\pm18$. The X-ray pulse profile is characterized by two narrow peaks which match the gross pulse profile observed at 1.4 GHz. Assuming a Crab-like spectrum the X-ray flux is in the range $f_x= 2-3\times 10^{-13}$ erg s$^{-1}$ cm$^{-2}$ ($0.1-2.4$ keV), implying an X-ray efficiency of $L_x/\dot{E}\sim 0.5-5 \times 10^{-3} (d/0.23 {kpc})^2$.Comment: Accepted for publication in Ap

Radio-wave propagation through a medium containing electron-density fluctuations described by an anisotropic Goldreich-Sridhar spectrum

We study the propagation of radio waves through a medium possessing density fluctuations that are elongated along the ambient magnetic field and described by an anisotropic Goldreich-Sridhar power spectrum. We derive general formulas for the wave phase structure function, visibility, angular broadening, diffraction-pattern length scales, and scintillation time scale for arbitrary distributions of turbulence along the line of sight, and specialize these formulas to idealized cases.Comment: 25 pages, 3 figures, submitted to Ap

Upper airway symptoms associate with the eosinophilic phenotype of COPD

Background: There is growing evidence that upper airway symptoms coexist with lower airway symptoms in COPD. Still, the prevalence and impact of upper airway disease on the nature and course of COPD remain unclear. We aimed to describe this in a cross-sectional study. // Methods: We examined a cohort of COPD patients with pulmonary function tests, induced sputum, blood eosinophils, atopy tests and computed tomography (CT) of the paranasal sinuses. Lower airway symptoms were assessed using the COPD Assessment Test (CAT), and upper airway symptoms were assessed using the nasal subdomain of the 22-item Sino Nasal Outcome Test (SNOT22nasal). We recruited patients from five sites in Denmark and Sweden. We excluded patients with a history of asthma. // Findings: In total, 180 patients (female 55%, age 67±8 years, forced expiratory volume in 1 s (FEV1 %) 52.4±16.6, Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage: A: 18%, B: 54%, C: 3%, D: 25%) were included in the study. Seventy-four patients (41%) reported high upper airway symptoms (UAS, defined as SNOT22nasal≥6) with a median score of 10 (IQR 8–13). Patients with high UAS reported higher CAT scores (17.4±7.5 versus 14.9±6.6, p<0.05) and displayed higher fractions of eosinophils in blood (median 3.0% (IQR 1.6–4.2%) versus 2.3% (IQR 1.4–3.1%), p<0.05) and in induced sputum (median 1.8% (IQR 0.3–7.1%) versus median 0.5% (IQR 0–1.7%), p<0.05). No differences in atopy, CT findings or exacerbation rates were observed. // Conclusion: COPD patients with upper airway disease showed increased evidence of eosinophilic disease and increased lower airway symptom burden

Vaccination against Foot-and-Mouth Disease : differentiating strategies and their epidemiological and economic consequences

The effectiveness of different control strategies against Foot-and-Mouth Disease (FMD) were investigated using epidemiological and economic models. A quick and large-scale vaccination within a radius of at least 2km is as effective as preemptive 1-km ring culling to mitigate FMD epidemics. Control measures should primarily target cattle farms. After the epidemic, most seropositive animals are expected on sheep farms and vaccinated cattle farms. An effective end-screening strategy should focus on these farms. Market acceptance by trade partners of products of vaccinated animals can limit the economic consequences of outbreaks of FMD.De effectiviteit van bestrijdingstrategieën tegen Mond-en-Klauwzeer (MKZ) is onderzochtmet behulp van epidemiologische en economische modellen. Het blijkt dat snelle en op grote schaal toegepaste vaccinatie in een straal van 2 km rond geïnfecteerde bedrijven net zo effectief is als ruimen in een straal van 1 km rond geïnfecteerde bedrijven bij het bestrijden van MKZ-uitbraken. Controlemaatregelen moeten vooral worden gericht op rundveebedrijven. Na de epidemie zijn de meeste seropositieve dieren te verwachten. De eindscreening zal zich op schapenbedrijven en gevaccineerde rundveebedrijven moeten richten. Acceptatie door internationale handelspartners van producten van gevaccineerde dieren kan de economische gevolgen van een uitbraak van MKZ beperken

Using Pulsars to Detect Massive Black Hole Binaries via Gravitational Radiation: Sagittarius A* and Nearby Galaxies

Pulsar timing measurements can be used to detect gravitational radiation from massive black hole binaries. The ~106d quasi-periodic flux variations in Sagittarius A* at radio wavelengths reported by Zhao, Bower, & Goss (2001) may be due to binarity of the massive black hole that is presumed to be responsible for the radio emission. A 106d equal-mass binary black hole is unlikely based on its short inspiral lifetime and other arguments. Nevertheless the reported quasi-periodicity has led us to consider whether the long-wavelength gravitational waves from a conjectured binary might be detected in present or future precision timing of millisecond pulsars. While present timing cannot reach the level expected for an equal-mass binary, we estimate that future efforts could. This inquiry has led us to further consider the detection of binarity in the massive black holes now being found in nearby galaxies. For orbital periods of ~2000d where the pulsar timing measurements are most precise, we place upper limits on the mass ratio of binaries as small as 0.06.Comment: 7 pages, 2 eps figures, accepted for publication in Ap