6,340 research outputs found
Genetic Variation in Resistance of Scotch Pine to Zimmerman Pine Moth
(excerpt)
Scotch pine (Pinus sylvestris L.), a forest tree introduced from Eurasia, is commonly planted for Christmas tree and timber use in northeastern United States. In this country it has numerous insect enemies. Among the most important are European pine shoot moth, Rhyacionia buoliana (Schiffermiieller); pine root collar weevil, Hylobius radicis Buchanan;,European pine sawfly, Neodiprion sertifer (Geoffroy); and eastern white-pine shoot borer, Eucosma gloriola Heinrich. Previous studies (Wright et al., 1967; Wright and Wilson, 1972; Steiner, 1974) have revealed large genetic differences in resistance to some of these pests.
Another destructive pest is the Zimmerman pine moth, Dioryctria zimmermani (Grote). In 1968 this insect, native to the United States, was found attacking trees in a Scotch pine provenance test in southwestern Michigan. The attack rate was heavy and by 1973 it was obvious that some rams or varieties were attacked more heavily than others. This is a report on those differences
The Brauer-Manin Obstruction and Sha[2].
We discuss the Brauer-Manin obstruction on del Pezzo surfaces of degree 4. We outline a detailed algorithm for computing the obstruction and provide associated programs in magma. This is illustrated with the computation of an example with an irreducible cubic factor in the singular locus of the defining pencil of quadrics (in contrast to previous examples, which had at worst quadratic irreducible factors). We exploit the relationship with the Tate-Shafarevich group to give new types of examples of Sha[2], for families of curves of genus 2 of the form y^2 = f(x), where f(x) is a quintic containing an irreducible cubic factor
The RCB star V854 Cen is surrounded by a hot dusty shell
Aims : The hydrogen-deficient supergiants known as R Coronae Borealis (RCB)
stars might be the result of a double-degenerate merger of two white dwarfs
(WDs), or a final helium shell flash in a planetary nebula central star. In
this context, any information on the geometry of their circumstellar
environment and, in particular, the potential detection of elongated
structures, is of great importance. Methods : We obtained near-IR observations
of V854 Cen with the AMBER recombiner located at the Very Large Telescope
Interferometer (VLTI) array with the compact array (B35m) in 2013 and the
long array (B140m) in 2014. At each time, V854 Cen was at maximum light.
The - and -band continua were investigated by means of spectrally
dependant geometric models. These data were supplemented with mid-IR VISIR/VLT
images. Results : A dusty slightly elongated over density is discovered both in
the - and -band images. With the compact array, the central star is
unresolved (\,mas), but a flattened dusty environment of mas is discovered whose flux increases from about 20% in the
band to reach about 50% at 2.3\micron, which indicates hot
(T1500\,K) dust in the close vicinity of the star. The major axis is
oriented at a position angle (P.A.) of 12629. Adding the long-array
configuration dataset provides tighter constraints on the star diameter
( mas), a slight increase of the overdensity to
mas and a consistent P.A. of 13349. The closure phases, sensitive to
asymmetries, are null and compatible with a centro-symmetric, unperturbed
environment excluding point sources at the level of 3% of the total flux in
2013 and 2014. The VISIR images exhibit a flattened aspect ratio at the 15-20%
level at larger distances (1\arcsec) with a position angle of
9219, marginally consistent with the interferometric observations.
Conclusions : This is the first time that a moderately elongated structure has
been observed around an RCB star. These observations confirm the numerous
suggestions for a bipolar structure proposed for this star in the literature,
which were mainly based on polarimetric and spectroscopic observations.Comment: Accepted by A\&A, new version after language editing, Astronomy and
Astrophysics (2014
V838 Monocerotis: the central star and its environment a decade after outburst
Aims. V838 Monocerotis erupted in 2002, brightened in a series of outbursts,
and eventually developed a spectacular light echo. A very red star emerged a
few months after the outburst. The whole event has been interpreted as the
result of a merger. Methods. We obtained near-IR and mid-IR interferometric
observations of V838 Mon with the AMBER and MIDI recombiners located at the
Very Large Telescope Interferometer (VLTI) array. The MIDI two-beam
observations were obtained with the 8m Unit Telescopes between October 2011 and
February 2012. The AMBER three-beam observations were obtained with the compact
array (Bm) in April 2013 and the long array (B140m) in May 2014,
using the 1.8m Auxiliary Telescopes. Results. A significant new result is the
detection of a compact structure around V838 Mon, as seen from MIDI data. The
extension of the structure increases from a FWHM of 25 mas at 8 {\mu}m to 70
mas at 13 {\mu}m. At the adopted distance of D = 6.1 0.6 kpc, the dust is
distributed from about 150 to 400 AU around V838 Mon. The MIDI visibilities
reveal a flattened structure whose aspect ratio increases with wavelength. The
major axis is roughly oriented around a position angle of -10 degrees, which
aligns with previous polarimetric studies reported in the literature. This
flattening can be interpreted as a relic of the 2002 eruption or by the
influence of the currently embedded B3V companion. The AMBER data provide a new
diameter for the pseudo-photosphere, which shows that its diameter has
decreased by about 40% in 10yrs, reaching a radius R = 750 200
R (3.5 1.0 AU). Conclusions. After the 2002 eruption,
interpreted as the merging of two stars, it seems that the resulting source is
relaxing to a normal state. The nearby environment exhibits an equatorial
over-density of dust up to several hundreds of AU.Comment: Astronomy and Astrophysics (2014) Will be set by the publishe
The professional socialisation of headteachers in England: Further findings from the National Headteacher Survey
This paper reports on a further investigation of data first accumulated through a national survey of headteachers conducted in 1999. The survey was conducted by means of a self-completion postal questionnaire with a stratified random sample of 10 per cent serving headteachers in England, totalling 2285 potential respondents in all. Completed returns were received from 1405 headteachers, an overall response rate of 62 per cent. Initial findings from the survey have subsequently been published as conference papers and journal articles (Male, 2000; Male and Hvizdak, 2000; Male and Male, 2001, Male 2001). The survey primarily sought to establish the respondents’ perceived state of readiness for the demands of the headteacher position in a number of job categories and competencies. A secondary aim was to allow respondents to attribute reasons to their state of readiness where they perceived it to be adequate or better. A third aim was to seek opinion from the respondents as to what provision and support would be beneficial to headteachers in their first two years in post. This further investigation has been commissioned by the National College for School Leadership and has been conducted by the original author, aided by two serving headteachers who have been appointed as research associates by the college during the period January to July of 2002
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Increasing the intensity and comprehensiveness of aphasia services: identification of key factors influencing implementation across six countries
Background: Aphasia services are currently faced by increasing evidence for therapy of greater intensity and comprehensiveness. Intensive Comprehensive Aphasia Programs (ICAPs) combine these elements in an evidence-based, time-limited group program. The incorporation of new service delivery models in routine clinical practice is, however, likely to pose challenges for both the service provider and administering clinicians. This program of research aims to identify these challenges from the perspective of aphasia clinicians from six countries and will seek to trial potential solutions. Continual advancements in global communication technologies suggest that solutions will be easily shared and accessed across multiple countries.
Aims: To identify the perceived and experienced barriers and facilitators to the implementation of 1) intensive aphasia services, 2) comprehensive aphasia services, and 3) ICAPs, from aphasia clinicians across six countries.
Methods and procedures: A qualitative enquiry approach included data from six focus groups (n = 34 participants) in Australia, New Zealand, Canada, United States of America (USA), United Kingdom (UK), and Ireland. A thematic analysis of focus group data was informed by the Theoretical Domains Framework (TDF).
Outcomes and results: Five prominent theoretical domains from the TDF influenced the implementation of all three aphasia service types across participating countries: environmental context and resources, beliefs about consequences, social/professional role and identity, skills, and knowledge. Four overarching themes assisted the identification and explanation of the key barriers and facilitators: 1. Collaboration, joint initiatives and partnerships, 2. Advocacy, the promotion of aphasia services and evidence-based practice, 3. Innovation, the ability to problem solve challenges, and 4. Culture, the influence of underlying values.
Conclusions: The results of this study will inform the development of a theoretically informed intervention to improve health services’ adherence to aphasia best practice recommendations
Total column CO_2 measurements at Darwin, Australia – site description and calibration against in situ aircraft profiles
An automated Fourier Transform Spectroscopic (FTS) solar observatory was established in Darwin, Australia in August 2005. The laboratory is part of the Total Carbon Column Observing Network, and measures atmospheric column abundances of CO_2 and O_2 and other gases. Measured CO_2 columns were calibrated against integrated aircraft profiles obtained during the TWP-ICE campaign in January–February 2006, and show good agreement with calibrations for a similar instrument in Park Falls, Wisconsin. A clear-sky low airmass relative precision of 0.1% is demonstrated in the CO2 and O2 retrieved column-averaged volume mixing ratios. The 1% negative bias in the FTS X_(CO_2) relative to the World Meteorological Organization (WMO) calibrated in situ scale is within the uncertainties of the NIR spectroscopy and analysis
New observations regarding deterministic, time-reversible thermostats and Gauss's principle of least constraint
Deterministic thermostats are frequently employed in nonequilibrium molecular dynamics simulations in order to remove the heat produced irreversibly over the course of such simulations. The simplest thermostat is the Gaussian thermostat, which satisfies Gauss's principle of least constraint and fixes the peculiar kinetic energy. There are of course infinitely many ways to thermostat systems, e.g., by fixing [summation]i|pi|嫱. In the present paper we provide, for the first time, convincing arguments as to why the conventional Gaussian isokinetic thermostat (影) is unique in this class. We show that this thermostat minimizes the phase space compression and is the only thermostat for which the conjugate pairing rule holds. Moreover, it is shown that for finite sized systems in the absence of an applied dissipative field, all other thermostats (囮ot-equal]1) perform work on the system in the same manner as a dissipative field while simultaneously removing the dissipative heat so generated. All other thermostats (囮ot-equal]1) are thus autodissipative. Among all 場hermostats, only the 影 Gaussian thermostat permits an equilibrium state.Full Tex
Probiotic effects of lactic acid bacteria against Vibrio alginolyticus in Penaeus (Fenneropenaeus) indicus (H. Milne Edwards)
Cell free extracts of four strains of Lactic acid bacteria (LAB) viz. Lactobacillus. acidophilus,
Streptococcus.cremoris, Lactobacillus bulgaricus –56 and Lactobacillus bulgaricus –57 inhibited
growth of Vibrio alginolyticus in nutrient broth. The antagonism of LAB to Vibrio
alginolyticus was further confirmed by streak plating wherein suppression of growth of Vibrio
was obtained.
Juveniles of Penaeus indicus (average weight 0.985 ± 0.1 g) on administering orally a
moist feed base containing 5 × 106 cells·g of the four LAB probionts for a period of four weeks
showed better survival (56 to 72%) when challenged with V. alginolyticus by intra-muscular
injection of 0.1 ml containing 3 × 109 cells·ml. Animals maintained on a diet devoid of bacterial
biomass exhibited 80% mortality
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