Accretion by Isolated Neutron Stars

Accretion of interstellar material by an isolated neutron star is discussed. The point I address here is the interaction between the accretion flow and the stellar magnetosphere. I show that the interchange instabilities of the magnetospheric boundary under the conditions of interest are basically suppressed. The entry of the material into the magnetosphere is governed by diffusion. Due to this reason the persistent accretion luminosity of isolated neutron stars is limited to < 4E+26 erg/s. These objects can also appear as X-ray bursters with the burst durations of about 30 minutes and repetition time of about 1E+5 yr. This indicates that the number of the accreting isolated neutron stars which could be observed with recent and modern X-ray missions is a few orders of magnitude smaller than that previously estimated.Comment: 3 pages, to appear in Astrophysics and Space Science, in the proceedings of "Isolated Neutron Stars: from the Interior to the Surface", edited by D. Page, R. Turolla and S. Zan

Latest results on Jovian disk X-rays from XMM-Newton

We present the results of a spectral study of the soft X-ray emission (0.2-2.5 keV) from low-latitude (`disk') regions of Jupiter. The data were obtained during two observing campaigns with XMM-Newton in April and November 2003. While the level of the emission remained approximately the same between April and the first half of the November observation, the second part of the latter shows an enhancement by about 40% in the 0.2-2.5 keV flux. A very similar, and apparently correlated increase, in time and scale, was observed in the solar X-ray and EUV flux. The months of October and November 2003 saw a period of particularly intense solar activity, which appears reflected in the behaviour of the soft X-rays from Jupiter's disk. The X-ray spectra, from the XMM-Newton EPIC CCD cameras, are all well fitted by a coronal model with temperatures in the range 0.4-0.5 keV, with additional line emission from Mg XI (1.35 keV) and Si XIII (1.86 keV): these are characteristic lines of solar X-ray spectra at maximum activity and during flares. The XMM-Newton observations lend further support to the theory that Jupiter's disk X-ray emission is controlled by the Sun, and may be produced in large part by scattering, elastic and fluorescent, of solar X-rays in the upper atmosphere of the planet.Comment: 17 pages, 7 figures, accepted for publication in a special issue of Planetary and Space Scienc

Polysensitization in the European general population:The EDEN Fragrance Study

INTRODUCTION: Polysensitization is currently defined as contact sensitization to three or more non-related allergens of the European baseline series. Reported prevalences of polysensitization are mainly from clinical populations, as studies in the general population are scarce. OBJECTIVES: To determine the prevalences of polysensitization in the European general population. MATERIALS AND METHODS: In five European countries (The Netherlands, Germany, Italy, Portugal and Sweden) a random sample (N=3119) from the general population (18-74 years) was patch tested. Patch testing was performed according to the International Contact Dermatitis Research Group guidelines. Both TRUE Test and investigator-loaded chamber systems were used, testing for a total of 47 allergens, including the individual fragrance allergens of fragrance mix (FM) I and FM II. Reading was performed at day 3. Polysensitization was defined as sensitization to 3 or more non-related allergens. The following positive reactions were pooled as one: FM I and one or more substances of FM I; FM II and one or more substances of FM II; carba mix and thiuram mix; mercapto mix and 2-mercaptobenzothiazole; formaldehyde, quaternium 15, diazolidinyl urea and imidazolidinyl urea. RESULTS: Overall, the age-standardized prevalence of polysensitization was 2.6% (95% confidence interval [CI] 2.1-3.2). The agestandardized prevalences stratified per country were: The Netherlands: 4.0% (95% CI 2.5-6.0); Germany: 3.2% (95% CI 2.3-4.4); Portugal: 2.6% (95% CI 1.5-4.3); Sweden: 1.5% (95% CI 0.7-2.9); Italy 1.1% (95% CI 0.5-2.3). Of the polysensitized population, the majority was female ≥ 40 years (42.0%) and minority was male &lt;40 years (8.6%). The age-standardized prevalences of one positive reaction was 19.2% (95% CI 17.9-20.7) and of one or two positive reactions (oligosensitization) was 25.6% (95% CI 24.1-27.2). Avoidance rates due to skin complaints were higher in polysensitized subjects compared to oligosensitized subjects and compared to subjects with negative patch test reactions. Avoidance of leave on products: polysensitized 44.3%; oligosensitized 32.9%; negative patch tests 23.7%. Avoidance of household or functional products: polysensitized 29.1%; oligosensitized 18.3%; negative patch tests 12.0%. CONCLUSION: Prevalences of polysensitization in the general population are presented for countries across Europe for the first time. Differences in prevalences are seen between different countries. Higher avoidance rates of scented products due to skin complaints were reported for leave-on and household or functional products in polysensitized subjects

Atopic dermatitis in the European general population: The EDEN Fragrance study

OBJECTIVES: To determine the prevalence of atopic dermatitis (AD) in the general European population and to assess differences in contact allergy and avoidance of products between subjects with AD in lifetime and those who had not. MATERIALS AND METHODS: In five European countries (The Netherlands, Germany, Italy, Portugal and Sweden) a random sample of 12 377 participants, aged 18 to 74 years were interviewed using a standardized questionnaire. Questions were asked about previous atopic dermatitis and avoidance of products because of a skin reaction. A random sample of 3119 participants was patch tested. TRUE Test panel 1, 2 and 3 and investigator-loaded chamber systems were used, testing for a total of 47 allergens, including the individual fragrance allergens of fragrance mix (FM) I and FM II. Reading was performed at day 3. RESULTS: The physician-diagnosed lifetime prevalence of AD was 7.1% (95% CI 6.7-7.6). The age-standardized physician diagnosed life time prevalences of AD stratified per country were: Germany: 9.4% (95% CI 8.5-10.3); The Netherlands: 8.5% (95% CI 7.2-10.1); Sweden: 7.2% (95% CI 6.1-8.4); Italy 4.2% (95% CI 3.3-5.3); Portugal: 3.3% (95% CI 2.6-4.2). The prevalence of contact allergy to at least one allergen was not significantly different between those with AD in lifetime (31.1%) and those without AD (27.8%). Males with AD were significantly more sensitized to allergens of TRUE Test panel 2 (14.9%) than those without AD (6.9%) (P = .026). The prevalence of contact allergy to individual allergens was not significantly different for those with AD and those without, except for p-phenylenediamine in males: AD (4.0%), no AD (0.7%) (P = .023). The prevalence of a positive patch test reaction to the group of preservatives was slightly albeit not significant (P <.09) higher in subjects with AD in lifetime (8.9%) compared to those without (6.2%). Subjects with AD in lifetime reported significantly more avoidance of products because of any skin reaction compared to subjects without AD, regarding leave on products, rinse off products, household products, jewels/metals and topical medication (all differences significant P <.001). This avoidance behaviour was independent from having a contact allergy and could be replicated in AD patients with and without contact allergy. CONCLUSION: The lifetime prevalence of atopic dermatitis was higher in Germany, the Netherlands and Sweden compared with Italy and Portugal. Although patients with atopic dermatitis reported significantly more avoidance of products due to skin problems they were not more frequently sensitized

High-time-resolution Measurements of the Polarization of the Crab Pulsar at 1.38 GHz

Using the Westerbork Synthesis Radio Telescope, we obtained high-time-resolution measurements of the full polarization of the Crab pulsar. At a resolution of 1/8192 of the 34 ms pulse period (i.e., 4.1 μs), the 1.38 GHz linear-polarization measurements are in general agreement with previous lower-time-resolution 1.4 GHz measurements of linear polarization in the main pulse (MP), in the interpulse (IP), and in the low-frequency component (LFC). We find the MP and IP to be linearly polarized at about 24% and 21% with no discernible difference in polarization position angle. However, contrary to theoretical expectations and measurements in the visible, we find no evidence for significant variation (sweep) in the polarization position angle over the MP, the IP, or the LFC. We discuss the implications, which appear to be in contradiction to theoretical expectations. We also detect weak circular polarization in the MP and IP, and strong (≈20%) circular polarization in the LFC, which also exhibits very strong (≈98%) linear polarization at a position angle of 40° from that of the MP or IP. The properties are consistent with the LFC, which is a low-altitude component, and the MP and IP, which are high-altitude caustic components. Current models for the MP and IP emission do not readily account for the absence of pronounced polarization changes across the pulse. We measure IP and LFC pulse phases relative to the MP consistent with recent measurements, which have shown that the phases of these pulse components are evolving with time