23,027 research outputs found
Development and evaluation of infrared sensitive image sensors for space astronomy
The experimental development and evaluation of infrared vidicons for use in solving high precision high flux broadband astronomical problems are discussed. Data cover the EOS, silicon, and doped germanium vidicons. Results are graphed and problems encountered using the vidicons in electrical cameras are reported
Honeylocust Twig-gall Midge (Diptera: Cecidomyiidae) in Michigan
Emergence and oviposition data were gathered for Neolasioptera brevis, a recently described pest of honeylocust. In 1984 the insects first emerged on 21 May and first oviposited on 4 June; in 1985 they first emerged on 28 April and first oviposited between 5-20 May. Average raceme length at emergence and at oviposition were 2.7 and 4.4 cm in 1984 and 2.6 and 4.8 cm in 1985. Approximate duration of the emergence period was one week. In 1985 observed oviposition wounds averaged 0.5/cm
Velocity dispersions in galaxies: 1: The SO galaxy NGC 7332
A Coude spectrum of the SO galaxy NGC 7332 with 0.9 A resolution from 4186 to 4364 A was obtained with the SEC vidicon television camera and the Hale telescope. Comparisons with spectra of G and K giant stars, numerically broadened for various Maxwellian velocity distributions, give a dispersion velocity in the line of sight of 160 + or - 20 km/sec with the best fit at G8III. The dispersion appears to be constant within + or - 35 km/sec out to 1.4 kpc (H = 100 km/sec/mpc). After correction for projection, the rotation curve has a slope of 0.16 km/sec/pc at the center and a velocity of 130 km/sec at 1.4 kpc where it is still increasing. For an estimated effective radius of 3.5 kpc enclosing half the light, the virial theorem gives a mass of 1.4 x 10 to the 11th power solar masses if the mass-to-light ratio is constant throughout the galaxy. The photographic luminosity is 8.3 x 10 to the 9th power solar luminosities so that the M/L ratio is 17
Extracting Radial Velocities of A- and B-type Stars from Echelle Spectrograph Calibration Spectra
We present a technique to extract radial velocity measurements from echelle
spectrograph observations of rapidly rotating stars ( km
s). This type of measurement is difficult because the line widths of
such stars are often comparable to the width of a single echelle order. To
compensate for the scarcity of lines and Doppler information content, we have
developed a process that forward-models the observations, fitting the radial
velocity shift of the star for all echelle orders simultaneously with the
echelle blaze function. We use our technique to extract radial velocity
measurements from a sample of rapidly rotating A- and B-type stars used as
calibrator stars observed by the California Planet Survey observations. We
measure absolute radial velocities with a precision ranging from 0.5-2.0 km
s per epoch for more than 100 A- and B-type stars. In our sample of 10
well-sampled stars with radial velocity scatter in excess of their measurement
uncertainties, three of these are single-lined binaries with long observational
baselines. From this subsample, we present detections of two previously unknown
spectroscopic binaries and one known astrometric system. Our technique will be
useful in measuring or placing upper limits on the masses of sub-stellar
companions discovered by wide-field transit surveys, and conducting future
spectroscopic binarity surveys and Galactic space-motion studies of massive
and/or young, rapidly-rotating stars.Comment: Accepted to ApJ
âMaturing Outâ as dilemmatic: Transitions towards relatively light drinking practices among UK University students
Objectives
University students in the UK engage in relatively high alcohol consumption levels, yet young adults, including students, now drink less than previously and abstain more. Against this cultural backdrop, our objective was to further understanding of âmaturing outâ of excessive drinking practices among students by focusing on drinking transitions that had taken place during university years.
Design
A qualitative interview study.
Methods
Semiâstructured interviews were conducted with ten 18â to 27âyearâold UK undergraduate university students who selfâidentified as light or nonâdrinkers. Interviews were audioârecorded, and anonymized interview transcripts were subjected to an experienceâfocused application of thematic analysis.
Results
Participants reported dilemmas involved in transitions from relatively high to low levels of alcohol consumption. One dilemma was characterized by managing to drink less (or nothing) without cutting off social options with university friends/peers. A second dilemma concerned not wishing to fully abandon the pleasures and increased social confidence that alcohol consumption could afford. Results also demonstrated that selfâreported drinking could contradict participantsâ selfâdefined âlight drinkerâ status.
Conclusions
This study reinforces the view that âmaturing outâ involves more than simply having gained new responsibilities during young adulthood. Recognition of these dilemmatic features of drinking transitions could be drawn on in novel campusâbased interventions. Such interventions may help strengthen realistic and sustainable moderate drinking by guiding students to anticipate potential difficulties involved in planned reductions in personal drinking but may also help foster studentsâ ability to view drinking choices as in transition rather than as permanent and enduring
Helium energy levels including corrections
The correction to energy is expressed in terms of an effective
Hamiltonian for an arbitrary state of helium. Numerical calculations
are performed for levels, and the previous result for the centroid
is corrected. While the resulting theoretical predictions for the ionization
energy are in moderate agreement with experimental values for , ,
and states, they are in significant disagreement for the singlet state
.Comment: 11 pages, with erratum submitted to Phys. Rev. A (2007
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