1,894 research outputs found

    Collective Interview on the History of Town Meetings

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    As illustrated in the introduction, the special issue ends with a ‘collective interview’ to some distinguished scholars that have given an important contribution to the study of New England Town Meetings. The collective interview has been realized by submitting three questions to our interviewees, who responded individually in written. The text of the answers has not been edited, if not minimally. However, the editors have broken up longer individual answers in shorter parts. These have been subsequently rearranged in an effort to provide, as much as possible, a fluid structure and a degree of interaction among the different perspectives provided by our interviewees on similar issues. The final version of this interview has been edited and approved by all interviewees

    Costs of colour change in fish: food intake and behavioural decisions

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    Many animals, particularly reptiles, amphibians, fish and cephalopods, have the ability to change their body colour, for functions including thermoregulation, signalling and predator avoidance. Many fish plastically darken their body colouration in response to dark visual backgrounds, and this functions to reduce predation risk. Here, we tested the hypotheses that colour change in fish (1) carries with it an energetic cost and (2) affects subsequent shoal and habitat choice decisions. We demonstrate that guppies (Poecilia reticulata) change colour in response to dark and light visual backgrounds, and that doing so carries an energetic cost in terms of food consumption. By increasing food intake, however, guppies are able to maintain growth rates and meet the energetic costs of changing colour. Following colour change, fish preferentially choose habitats and shoals that match their own body colouration, and maximise crypsis, thus avoiding the need for further colour change but also potentially paying an opportunity cost associated with restriction to particular habitats and social associates. Thus, colour change to match the background is complemented by behavioural strategies, which should act to maximise fitness in variable environments. © 2013. Published by The Company of Biologists Ltd

    Optical Spectroscopy of X-Mega targets in the Carina Nebula - VI. FO 15: a new O-Type double-lined eclipsing binary

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    We report the discovery of a new O-type double-lined spectroscopic binary with a short orbital period of 1.4 days. We find the primary component of this binary, FO 15, to have an approximate spectral type O5.5Vz, i.e. a Zero-Age-Main-Sequence star. The secondary appears to be of spectral type O9.5V. We have performed a numerical model fit to the public ASAS photometry, which shows that FO 15 is also an eclipsing binary. We find an orbital inclination of ~ 80 deg. From a simultaneous light-curve and radial velocity solution we find the masses and radii of the two components to be 30 +/- 1 and 16 +/- 1 solar masses and 7.5 +/- 0.5 and 5.3 +/- 0.5 solar radii. These radii, and hence also the luminosities, are smaller than those of normal O-type stars, but similar to recently born ZAMS O-type stars. The absolute magnitudes derived from our analysis locate FO 15 at the same distance as Eta Carinae. From Chandra and XMM X-ray images we also find that there are two close X-ray sources, one coincident with FO 15 and another one without optical counterpart. This latter seems to be a highly variable source, presumably due to a pre-main-sequence stellar neighbour of FO 15.Comment: 11 pages, 9 figures, 3 tables. Accepted for publication in MNRAS. Higher resolution version available at http://lilen.fcaglp.unlp.edu.ar/papers2006.htm

    Polarisation-independent Bragg gratings in ion-exchanged glass channel waveguides

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    The polarisation dependence of Bragg gratings photowritten in ion-exchanged glass waveguides is characterised for waveguides with different mask-opening widths and burial depths. It is found that polarisation-independent gratings can be written in waveguides with a wide variation in fabrication parameters

    Internal Pressure Measurement Techniques and Pressure Response in Wood During Treating Processes

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    The development of pressure inside wood during preservative impregnation was studied using Douglas-fir heartwood and ponderosa pine sapwood. Pressure sensors mounted on sample holders provided the most reliable measurements. As expected, pressure equilibrated most rapidly with air as the treatment medium and ponderosa pine as the test species. Pressure changes were relatively slow in Douglas-fir heartwood, suggesting that process conditions involving relatively rapid changes in pressure conditions will have little effect on fluid penetration away from the wood surface

    Decay Resistance of Saltwater-Exposed Douglas-Fir Piles

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    Wood that is submerged in fresh water for long periods has increased permeability and other changed properties. Wood that is submerged in salt water may absorb considerable quantities of salts, which may render the wood resistant to microbial colonization. In this report, we describe decay tests on Douglas-fir sapwood and heartwood after long-term exposure in the Great Salt Lake of Utah. This wood was generally resistant to fungal attack, but was susceptible to leaching. Scanning electron microscopic examination revealed that salt crystals in the wood were primarily sodium chloride, which was readily removed in a leaching procedure. Decay resistance attributed to saltwater exposure declined with prolonged leaching

    Internal Pressure Development During Supercritical Fluid Impregnation of Wood

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    Supercritical fluid impregnation has tremendous potential for effectively impregnating a variety of species, but little is known about the pressure response in wood during this process. Pressure response was studied in a number of wood species using specially designed high pressure probes, which allowed in-situ monitoring of the treatment process. Pressure response was relatively rapid in permeable species such as pine, but tended to lag in less permeable species. In some cases, the differences between surface and internal pressure exceeded the material properties of the wood, and crushing or fractures resulted. The results indicate that the rates of pressure application and release can be tailored to control pressure differentials to avoid wood damage

    Effect of Wood Characteristics on Pressure Responses During Supercritical Carbon Dioxide Treatment

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    The potential for using the anatomical properties of wood to predict response to supercritical fluid impregnation was investigated using an array of hardwood and softwood species. Longitudinal resin canals were a reasonable predictor of softwood response to pressure application, while radial gas permeability and/or fiber dimensions were useful for the same predictions in hardwoods. Most other anatomical characteristics were poorly correlated with pressure response. The results suggest that there is some ability to use limited anatomical measurements to predict the receptivity of a given species to supercritical fluid impregnation, thereby reducing the need for iterative treatment trials to assess suitability of a species for use in this process

    Optical spectroscopy of X-MEGA targets I. CPD -59 2635: A New Double-Lined O type Binary in the Carina Nebula

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    Optical spectroscopy of CPD -59 2635, one of the O-type stars in the open cluster Trumpler 16 in the Carina Nebula, reveals this star to be a double-lined binary system. We have obtained the first radial velocity orbit for this system, consisting of a circular solution with a period of 2.2999 days and semi amplitudes of 208 and 273 km/s. This results in minimum masses of 15 and 11 Msol for the binary components of CPD -59 2635, which we classified as O8V and O9.5V, though spectral type variations of the order of 1 subclass, that we identify as the Struve-Sahade effect, seem to be present in both components. From ROSAT HRI observations of CPD -59 2635 we determine a luminosity ratio log(L_x/L_bol)~ -7, which is similar to that observed for other O-type stars in the Carina Nebula region. No evidence of light variations is present in the available optical or X-rays data sets

    Effects of nebulised iloprost on pulmonary function and gas exchange in severe pulmonary hypertension

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    SummaryNebulised iloprost is established therapy of severe pulmonary hypertension; however, the effects on the bronchoalveolar compartment have not been investigated so far. We studied the short- and long-term effects of nebulised iloprost on pulmonary function tests and gas exchange in 63 patients with severe pulmonary hypertension (idiopathic n=17, chronic thromboembolism n=15, connective tissue disease n=12, congenital heart disease n=11, respiratory diseases n=8). Patients received iloprost in increasing dose up to 140μg iloprost/24h via an ultrasonic nebuliser.Short-term effects were assessed before and after every nebulisation: peak expiration flow decreased in mean by 1.9% (423±98 to 415±98) and percutaneous oxygen saturation increased in mean by 0.7% (90±6 to 91±5) post-nebulisation. There were no significant differences concerning underlying diagnosis or dose of nebulised iloprost. Within 3 months, 9 patients stopped treatment due to non-compliance with frequent nebulisations (n=3), or severe side effects (n=4); 2 patients with additional obstructive lung disease developed bronchoconstriction.Long-term effects were assessed by pulmonary function tests and gas exchange parameters at baseline and after 3 months treatment. There were no significant differences after 3 months therapy neither in FEV1, FVC, TLC, residual volume nor in diffusions capacity, SO2 at rest and during 6min walking test, also in respect of the underlying diseases. However, there was a significant increase in 6min walking distance (6 MWD) after 3 months (246±113 to 294±115m, P<0.05).In conclusion, treatment with nebulised iloprost leads to functional improvement in severe pulmonary hypertension without systematic adverse short- and long-term effects on pulmonary function test or gas exchange. Patients with additional obstructive lung disease might develop bronchoconstriction. Severe side effects leading to discontinuation of treatment occurred in 9% of patients
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