3,369 research outputs found
Writing across the curriculum in secondary education
Academic writing is an undervalued practice in secondary education. Many teachers outside of the English Language Arts struggle to implement writing into their curriculum due to their lack of confidence in teaching different writing skills and the amount of time teaching and assessing writing can require. Writing is extremely beneficial to students developing content knowledge and discursive writing skills; however, because not many teaching emphasize the importance of writing, students do not develop necessary writing skills. In California, 49.88 percent of students in grades 3-11 who participated in the California Assessment of Students Performance and Progress (CAASPP) did not meet the standards in English Language Arts (Torlakson, 2018). This study researches secondary education teachers in Northern California to understand how they teach writing and areas where they need support to more successfully bring writing into their classrooms to promote student literacy
Quasars Clustering at z approx 3 on Scales less sim 10 h^{-1} Mpc
We test the hypothesis whether high redshift QSOs would preferentially appear
in small groups or pairs, and if they are associated with massive, young
clusters. We carried out a photometric search for \Ly emitters on scales
Mpc, in the fields of a sample of 47 known
QSOs. Wide and narrow band filter color-magnitude diagrams were generated for
each of the fields. A total of 13 non resolved objects with a
significant color excess were detected as QSO candidates at a redshift similar
to that of the target. All the candidates are significantly fainter than the
reference QSOs, with only 2 of them within 2 magnitudes of the central object.
Follow-up spectroscopic observations have shown that 5, i.e., about 40% of the
candidates, are QSOs at the same redshift of the target; 4 are QSOs at
different z (two of them probably being a lensed pair at z = 1.47); 2
candidates are unresolved HII galaxies at z0.3; one unclassified and one
candidate turned out to be a CCD flaw. These data indicate that at least 10% of
the QSOs at z3 do have companions.
We have also detected a number of resolved, rather bright \Ly Emitter
Candidates. Most probably a large fraction of them might be bright galaxies
with [OII] emission, at z 0.3. The fainter population of our
candidates corresponds to the current expectations. Thus, there are no strong
indication for the existence of an overdensity of \Ly galaxies brighter than m
25 around QSOs at 3.Comment: 29 pages, 8 figures, tar gzip LaTex file, accepted to appear in Ap
On the use of scaling relations for the Tolman test
The use of relations between structural parameters of early type galaxies to
perform the Tolman test is reconsidered. Scaling relations such as the FP or
the Kormendy relation, require the transformation from angular to metric sizes,
to compare the relation at different z values. This transformation depends on
the assumed world model: galaxies of a given angular size, at a given z, are
larger (in kpc) in a non-expanding universe than in an expanding one.
Furthermore, the luminosities of galaxies are expected to evolve with z in an
expanding model. These effects are shown to conspire to reduce the difference
between the predicted SB change with redshift in the expanding and non
expanding cases. We find that the predictions for the visible photometric bands
of the expanding models with passive luminosity evolution are very similar to
those of the static model till z about 1, and therefore, the test cannot
distinguish between the two world models. Recent good quality data are
consistent with the predictions from both models. In the K-band, where the
expected (model) luminosity evolutionary corrections are smaller, the
differences between the xpanding and static models amount to about 0.4 (0.8)
magnitudes at z = 0.4 (1). It is shown that, due to that small difference
between the predictions in the covered z-range, and to the paucity and
uncertainties of the relevant SB photometry, the existing K-band data is not
adequate to distinguish between the different world metrics, and cannot be yet
used to discard the static case. It is pointed out that the scaling relations
could still be used to rule out the non-evolving case if it could be shown that
the coefficients change with the redshift.Comment: Latex, 15 pages with 2 figures. To be published in ApJ Letter
Trends, over 14 years, in the ground cover on an unimproved western hill grazed by sheep, and associated trends in animal performance
peer-reviewedThe frequency of individual plant species at ground level and the species composition of the unimproved vegetation on a western hill farm, stocked with Scottish Blackface sheep, were monitored from 1995 to 2008. Performance criteria of the flock that relied totally, or almost totally, on this vegetation for sustenance from 1994 to 2011 were evaluated. The frequency of vegetation increased over time (from 65% to 82% of the surface area; P 60% better, depending on the variable, than similar flocks in the National Farm Survey at comparable stocking rates. A well-defined rational management system can sustain a productive sheep enterprise on unimproved hill land without negative consequences for the frequency or composition of the vegetation.PUBLISHEDpeer-reviewe
How Dry Are Red Mergers?
The focus of current research in galaxy evolution has increasingly turned to
understanding the effect that mergers have on the evolution of systems on the
red sequence. For those interactions purported to occur dissipationlessly (so
called "dry mergers"), it would appear that the role of gas is minimal.
However, if these mergers are not completely dry, then even low levels of gas
may be detectable. The purpose of our study is to test whether early type
galaxies with HI in or around them, or "wet" ellipticals, would have been
selected as dry mergers by the criteria in van Dokkum (2005, AJ, 130, 2647). To
that end, we examine a sample of 20 early types from the HI Rogues Gallery with
neutral hydrogen in their immediate environs. Of these, the 15 brightest and
reddest galaxies match the optical dry merger criteria, but in each case, the
presence of HI means that they are not truly dry.Comment: 8 pages plus 1 table and 5 figures; accepted for publication in A
The Addressee of the Third Kingship Oration of Dio Chrysostom
This oration by Dio Chrysostom was delivered in the presence of Trajan, as most scholars assume, not of Nerva, as P. Desideri (Dione di Prusa, Messina-Firenze 1978, 279) believes
The complex velocity distribution of galaxies in Abell 1689: implications for mass modelling
The Abell 1689 galaxy cluster has recently become a subject of intensive
study. Thanks to its intermediate redshift (z=0.183) its mass distribution can
be reconstructed using numerous methods including gravitational lensing, galaxy
kinematics and X-ray imaging. The methods used to yield conflicting mass
estimates in the past and recently the cluster mass distribution has been
claimed to be in conflict with standard CDM scenarios due to rather large
concentration and steep mass profile obtained from detailed studies of
Broadhurst et al. using lensing. By studying in detail the kinematics of about
200 galaxies with measured redshifts in the vicinity of the cluster we show
that the cluster is probably surrounded by a few structures, quite distant from
each other, but aligned along the line of sight. We support our arguments by
referring to cosmological N-body simulations and showing explicitly that
distant, non-interacting haloes can produce entangled multi-peak line-of-sight
velocity distributions similar to that in A1689. We conclude that it is
difficult to estimate the cluster mass reliably from galaxy kinematics, but the
value we obtain after applying a simple cut-off in velocity agrees roughly with
the mass estimated from lensing. The complicated mass distribution around the
cluster may however increase the uncertainty in the determination of the
density profile shape obtained with weak lensing.Comment: 5 pages, 4 figures, revised version accepted for publication in MNRAS
Letter
Extracting H flux from photometric data in the J-PLUS survey
We present the main steps that will be taken to extract H emission
flux from Javalambre Photometric Local Universe Survey (J-PLUS) photometric
data. For galaxies with , the H+[NII] emission is
covered by the J-PLUS narrow-band filter . We explore three different
methods to extract the H + [NII] flux from J-PLUS photometric data: a
combination of a broad-band and a narrow-band filter ( and ), two
broad-band and a narrow-band one (, and ), and a SED-fitting
based method using 8 photometric points. To test these methodologies, we
simulated J-PLUS data from a sample of 7511 SDSS spectra with measured
H flux. Based on the same sample, we derive two empirical relations to
correct the derived H+[NII] flux from dust extinction and [NII]
contamination. We find that the only unbiased method is the SED fitting based
one. The combination of two filters underestimates the measurements of the
H + [NII] flux by a 28%, while the three filters method by a 9%. We
study the error budget of the SED-fitting based method and find that, in
addition to the photometric error, our measurements have a systematic
uncertainty of a 4.3%. Several sources contribute to this uncertainty:
differences between our measurement procedure and the one used to derive the
spectroscopic values, the use of simple stellar populations as templates, and
the intrinsic errors of the spectra, which were not taken into account. Apart
from that, the empirical corrections for dust extinction and [NII]
contamination add an extra uncertainty of 14%. Given the J-PLUS photometric
system, the best methodology to extract H + [NII] flux is the
SED-fitting based one. Using this method, we are able to recover reliable
H fluxes for thousands of nearby galaxies in a robust and homogeneous
way.Comment: 11 pages, 14 figures. Minor changes to match the published versio
- …