Influence of sensitization and allergen provocation procedures on the development of allergen-induced bronchial hyperreactivity in conscious, unrestrained guinea-pigs

The effects of different sensitization and allergen provocation regimens on the development of allergen-induced bronchial hyperreactivity (BHR) to histamine were investigated in conscious, unrestrained guinea-pigs. Similar early and late phase asthmatic reactions, BHR for inhaled histamine after the early (6 h) as well as after the late reaction (24 h), and airway inflammation were observed after a single allergen provocation in animals sensitized to produce mainly IgG or IgE antibodies, respectively. Repeating the allergen provocation in the IgE-sensitized animals after 7 days, using identical provocation conditions, resulted in a similar development of BHR to histamine inhalation. Repetition of the allergen provocation during 4 subsequent days resulted in a decreased development of BHR after each provocation, despite a significant increase in the allergen provocation dose necessary to obtain similar airway obstruction. The number of inflammatory cells in the bronchoalveolar lavage was not significantly changed after repeated provocation, when compared with a single allergen provocation. Finally, we investigated allergen-induced bronchial hyperreactivity by repetition of the sensitization procedure at day 7 and 14 (booster), followed by repeated allergen provocation twice a week for 5 weeks. Surprisingly, no BHR to histamine could be observed after either provocation, while the number of inflammatory cells in the bronchoalveolar lavage fluid after 5 weeks was enhanced compared with controls. These data indicate that both IgE and IgG sensitized guinea-pigs may develop bronchial hyperreactivity after a single allergen provocation. Repeated allergen exposure of IgE sensitized animals causes a gradual fading of the induced hyperreactivity despite the on-going presence of inflammatory cells in the airways, indicating a mechanism of reduced cellular activation

Black Hole Mass, Velocity Dispersion and the Radio Source in AGN

The recent discovery of a correlation between nuclear black hole mass, M_bh, and the stellar velocity dispersion (Gebhardt et al. 2000, Ferrarese and Merritt 2000), in elliptical galaxies and spiral bulges, has raised the question whether such a relationship exists for AGN. Estimates of M_bh for many AGN, made using reverberation mapping techniques, allow exploration of the relationship between black hole mass, the host galaxy and the energetics of nuclear emission. However, since only a few AGN have both M_bh and velocity dispersion measurements, we use the [OIII] 5007 emission line widths on the assumption that for most AGN the forbidden line kinematics are dominated by virial motion in the host galaxy bulge. We find that a relation does exist between M_bh and [OIII] line width for AGN which is similar to the one found by Gebhardt et al. 2000, although with more scatter as expected if secondary influences on the gas kinematics are also present. Our conclusion is that both active and inactive galaxies follow the same relationship between black hole mass and bulge gravitational potential. We find no compelling evidence for systematic differences in the mass estimates from reverberation mapping and stellar dynamics. We also find that for radio quiet AGN the radio power and black hole mass are highly correlated linking emission on scales of kiloparsecs with the nuclear energy source.Comment: 4 pages, uses emulateapj5.sty and aastex, 2 figures, 1 table accepted for publication in the Astrophysical Journa

Estimates on returnable packaging material

When a beer company replaces its returnable packaging materials, for exam-ple when updating the design of a bottle, it needs to know in advance how much new material will be needed. Dutch beer brewer Heineken submitted the question of estimating the returnable packaging materials to the 2013 Studygroup Mathe-matics with Industry. In this report, we present both stochastic flow models and a queueing model to estimate the amount of returnable packaging material present in the market. Furthermore, we give recommendations on what data to collect, and how to sample this data in an unbiased way in order to increase accuracy of the estimation. Keywords: Modelling, Markov Chain, Stochastic Differential Equation, Queue-ing Theor

Arginase strongly impairs neuronal nitric oxide-mediated airway smooth muscle relaxation in allergic asthma

BACKGROUND: Using guinea pig tracheal preparations, we have recently shown that endogenous arginase activity attenuates inhibitory nonadrenergic noncholinergic (iNANC) nerve-mediated airway smooth muscle relaxation by reducing nitric oxide (NO) production – due to competition with neuronal NO-synthase (nNOS) for the common substrate, L-arginine. Furthermore, in a guinea pig model of allergic asthma, airway arginase activity is markedly increased after the early asthmatic reaction (EAR), leading to deficiency of agonist-induced, epithelium-derived NO and subsequent airway hyperreactivity. In this study, we investigated whether increased arginase activity after the EAR affects iNANC nerve-derived NO production and airway smooth muscle relaxation. METHODS: Electrical field stimulation (EFS; 150 mA, 4 ms, 4 s, 0.5 – 16 Hz)-induced relaxation was measured in tracheal open-ring preparations precontracted to 30% with histamine in the presence of 1 μM atropine and 3 μM indomethacin. The contribution of NO to EFS-induced relaxation was assessed by the nonselective NOS inhibitor N(ω)-nitro-L-arginine (L-NNA, 100 μM), while the involvement of arginase activity in the regulation of EFS-induced NO production and relaxation was investigated by the effect of the specific arginase inhibitor N(ω)-hydroxy-nor-L-arginine (nor-NOHA, 10 μM). Furthermore, the role of substrate availability to nNOS was measured in the presence of exogenous L-arginine (5.0 mM). RESULTS: At 6 h after ovalbumin-challenge (after the EAR), EFS-induced relaxation (ranging from 3.2 ± 1.1% at 0.5 Hz to 58.5 ± 2.2% at 16 Hz) was significantly decreased compared to unchallenged controls (7.1 ± 0.8% to 75.8 ± 0.7%; P < 0.05 all). In contrast to unchallenged controls, the NOS inhibitor L-NNA did not affect EFS-induced relaxation after allergen challenge, indicating that NO deficiency underlies the impaired relaxation. Remarkably, the specific arginase inhibitor nor-NOHA normalized the impaired relaxation to unchallenged control (P < 0.05 all), which effect was inhibited by L-NNA (P < 0.01 all). Moreover, the effect of nor-NOHA was mimicked by exogenous L-arginine. CONCLUSION: The results clearly demonstrate that increased arginase activity after the allergen-induced EAR contributes to a deficiency of iNANC nerve-derived NO and decreased airway smooth muscle relaxation, presumably via increased substrate competition with nNOS

Statistical Properties of Radio Emission from the Palomar Seyfert Galaxies

We have carried out an analysis of the radio and optical properties of a statistical sample of 45 Seyfert galaxies from the Palomar spectroscopic survey of nearby galaxies. We find that the space density of bright galaxies (-22 mag <= M_{B_T} <= -18 mag) showing Seyfert activity is (1.25 +/- 0.38) X 10^{-3} Mpc^{-3}, considerably higher than found in other Seyfert samples. Host galaxy types, radio spectra, and radio source sizes are uncorrelated with Seyfert type, as predicted by the unified schemes for active galaxies. Approximately half of the detected galaxies have flat or inverted radio spectra, more than expected based on previous samples. Surprisingly, Seyfert 1 galaxies are found to have somewhat stronger radio sources than Seyfert 2 galaxies at 6 and 20 cm, particularly among the galaxies with the weakest nuclear activity. We suggest that this difference can be accommodated in the unified schemes if a minimum level of Seyfert activity is required for a radio source to emerge from the vicinity of the active nucleus. Below this level, Seyfert radio sources might be suppressed by free-free absorption associated with the nuclear torus or a compact narrow-line region, thus accounting for both the weakness of the radio emission and the preponderance of flat spectra. Alternatively, the flat spectra and weak radio sources might indicate that the weak active nuclei are fed by advection-dominated accretion disks.Comment: 18 pages using emulateapj5, 13 embedded figures, accepted by Ap

Rectification of thermal fluctuations in ideal gases

We calculate the systematic average speed of the adiabatic piston and a thermal Brownian motor, introduced in [Van den Broeck, Kawai and Meurs, \emph{Microscopic analysis of a thermal Brownian motor}, to appear in Phys. Rev. Lett.], by an expansion of the Boltzmann equation and compare with the exact numerical solution.Comment: 18 page

On the Population of Wind-Accreting Neutron Stars in the Galaxy

We explore the possibility that neutron stars accreting from the winds of main-sequence stellar companions account for a significant fraction of low-luminosity, hard X-ray sources (L_X <~ 10^35 ergs/s; 1-10 keV) in the Galaxy. This work was motivated by recent Chandra observations of the Galactic center by Wang et al. (2002). Our calculations indicate that many of the discrete X-ray sources detected in this survey may be wind-accreting neutron stars, and that many more may be discovered with deeper X-ray observations. We propose that an infrared observing campaign be undertaken to search for the stellar counterparts of these X-ray sources.Comment: submitted to ApJ Letter