7,231 research outputs found
Spacelab energetic ion mass spectrometer
Basic design criteria are given for an ion mass spectrometer for use in studying magnetospheric ion populations. The proposed instrument is composed of an electrostatic analyzer followed by a magnetic spectrometer and simultaneously measures the energy per unit and mass per unit charge of the ion species. An electromagnet is used for momentum analysis to extend the operational energy range over a much wider domain than is possible with the permanent magnets used in previous flights. The energetic ion source regions, ion energization mechanisms, field line tracing, coordinated investigations, and orbit considerations are discussed and operations of the momentum analyzer and of the electrostatic energy analyzer are examined
Creative Science Through Inquiry: Improving Teacher Self-Efficacy and Outcome Expectancy Through Adaptable, Mystery-Based Professional Development
Teacher self-efficacy is an important contributor to student outcomes, school climate and teacher retention. Outcome expectancy, a construct studied more commonly in health- and behaviour-related fields, may also positively impact school-related outcomes. Research shows that professional development can increase teacher confidence, but few studies have considered this connection for science-focused professional development, specifically. Our study assesses the impact of a science-focused, mystery-based professional development workshop for upper-elementary to high-school teachers. The hands-on, collaborative nature of this workshop allowed for generalisability to classrooms of various ability levels. Using the Science Teaching Efficacy Belief Instrument-A (STEBI-A) as a measure of science-teaching self-efficacy and outcome expectancy, we found that participants’ self-reported self-efficacy and outcome expectancy significantly increased (p < .001 for each) over the course of the two-week workshop. This outcome is especially relevant to schools and districts interested in improving student outcomes, school climate and teacher retention rates
Synchronous Behavior of Two Coupled Electronic Neurons
We report on experimental studies of synchronization phenomena in a pair of
analog electronic neurons (ENs). The ENs were designed to reproduce the
observed membrane voltage oscillations of isolated biological neurons from the
stomatogastric ganglion of the California spiny lobster Panulirus interruptus.
The ENs are simple analog circuits which integrate four dimensional
differential equations representing fast and slow subcellular mechanisms that
produce the characteristic regular/chaotic spiking-bursting behavior of these
cells. In this paper we study their dynamical behavior as we couple them in the
same configurations as we have done for their counterpart biological neurons.
The interconnections we use for these neural oscillators are both direct
electrical connections and excitatory and inhibitory chemical connections: each
realized by analog circuitry and suggested by biological examples. We provide
here quantitative evidence that the ENs and the biological neurons behave
similarly when coupled in the same manner. They each display well defined
bifurcations in their mutual synchronization and regularization. We report
briefly on an experiment on coupled biological neurons and four dimensional ENs
which provides further ground for testing the validity of our numerical and
electronic models of individual neural behavior. Our experiments as a whole
present interesting new examples of regularization and synchronization in
coupled nonlinear oscillators.Comment: 26 pages, 10 figure
Will the Scottish Cancer Target for the year 2000 be met? The use of cancer registration and death records to predict future cancer incidence and mortality in Scotland.
Cancer mortality data reflect disease incidence and the effectiveness of treatment. Incidence data, however, reflect the burden of disease in the population and indicate the need for prevention measures, diagnostic services and cancer treatment facilities. Monitoring of targets mandates that both be considered. The Scottish Cancer Target, established in 1991, proposed that a reduction of 15% in mortality from cancer in the under-65s should be achieved between 1986 and 2000. Each year in Scotland approximately 8300 persons under 65 are diagnosed with cancer and 4500 die from the disease. The most common malignancies, in terms of both incident cases and deaths, in the under-65s, are lung and large bowel cancer in males, and breast, large bowel and lung cancer in females. A decrease of 6% in the number of cancer cases diagnosed in males under 65 is predicted between 1986 and 2000, whereas the number of cases in females in the year 2000 is expected to remain at the 1986 level. In contrast, substantial reductions in mortality are expected for both sexes: 17% and 25% in males and females respectively. Demographic changes will influence the numbers of cancer cases and deaths in the Scottish population in the year 2000. However, long-term trends in the major risk factors, such as smoking, are likely to be the most important determinants of the future cancer burden
IFU observations of luminous type II AGN - I. Evidence for ubiquitous winds
We present observations of 17 luminous (log(L[O III]/L) > 8.7) local (z < 0.11) type II AGN.
Our aim is to investigate the prevalence and nature of AGN-driven outflows in these galaxies by
combining kinematic and ionization diagnostic information. We use non-parametric methods
(e.g. W80, the width containing 80 per cent of the line flux) to assess the line widths in the central
regions of our targets. The maximum values of W80 in each galaxy are in the range 400–1600 km
s−1, with a mean of 790 ± 90 km s−1. Such high velocities are strongly suggestive that these
AGN are driving ionized outflows. Multi-Gaussian fitting is used to decompose the velocity
structure in our galaxies. 14/17 of our targets require three separate kinematic components in
the ionized gas in their central regions. The broadest components of these fits have FWHM
= 530–2520 km s−1, with a mean value of 920 ± 50 km s−1. By simultaneously fitting
both the Hβ/[O III] and Hα/[N II] complexes, we construct ionization diagnostic diagrams for
each component. 13/17 of our galaxies show a significant (>95 per cent) correlation between
the [N II]/Hα ratio and the velocity dispersion of the gas. Such a correlation is the natural
consequence of a contribution to the ionization from shock excitation and we argue that this
demonstrates that the outflows from these AGN are directly impacting the surrounding ISM
within the galaxies.
Key words: galaxies: active – galaxies: evolution – galaxies: kinematics and dynamic
A survey for low luminosity quasars at redshift z~5
We present the results of a multi-colour (VIZ) survey for low luminosity
(M_B<-23.5) quasars with z~5 using the 12K CCD mosaic camera on CFHT. The
survey covers 1.8deg^2 to a limiting magnitude of m_z=22.5(Vega), about two
magnitudes fainter than the SDSS quasar survey. 20 candidates were selected by
their VIZ colours and spectra for 15 of these were obtained with GMOS on the
Gemini North telescope. A single quasar with z=4.99 was recovered, the
remaining candidates are all M stars.
The detection of only a single quasar in the redshift range accessible to the
survey (4.8<5.2) is indicative of a possible turn over in the luminosity
function at faint quasar magnitudes, and a departure from the form observed at
higher luminosities (in agreement with quasar lensing observations by Richards
etal (2003)). However, the derived space densitys, of quasars more luminous
than M_B(Vega)<-23.5, of 2.96x10^-7 Mpc^-3 is consistent at the 65% confidence
level with extrapolation of the quasar luminosity function as derived by Fan
etal (2001a) at m_i<19.6(Vega).Comment: 8 Pages, 8 Figures, accepted for publication in MNRA
The SAMI Galaxy Survey: Unveiling the nature of kinematically offset active galactic nuclei
We have observed two kinematically offset active galactic nuclei (AGN), whose
ionised gas is at a different line-of-sight velocity to their host galaxies,
with the SAMI integral field spectrograph (IFS). One of the galaxies shows gas
kinematics very different to the stellar kinematics, indicating a recent merger
or accretion event. We demonstrate that the star formation associated with this
event was triggered within the last 100 Myr. The other galaxy shows simple disc
rotation in both gas and stellar kinematics, aligned with each other, but in
the central region has signatures of an outflow driven by the AGN. Other than
the outflow, neither galaxy shows any discontinuity in the ionised gas
kinematics at the galaxy's centre. We conclude that in these two cases there is
no direct evidence of the AGN being in a supermassive black hole binary system.
Our study demonstrates that selecting kinematically offset AGN from
single-fibre spectroscopy provides, by definition, samples of kinematically
peculiar objects, but IFS or other data are required to determine their true
nature.Comment: MNRAS accepted. 14 pages, 11 figure
- …