2,158 research outputs found
A Global Photometric Analysis of 2MASS Calibration Data
We present results from the application of a global photometric calibration
(GPC) procedure to calibration data from the first 2 years of The Two Micron
All Sky Survey (2MASS). The GPC algorithm uses photometry of both primary
standards and moderately bright `tracer' stars in 35 2MASS calibration fields.
During the first two years of the Survey, each standard was observed on
approximately 50 nights, with about 900 individual measurements. Based on the
photometry of primary standard stars and secondary tracer stars and under the
assumption that the nightly zeropoint drift is linear, GPC ties together all
calibration fields and all survey nights simultaneously, producing a globally
optimized solution. Calibration solutions for the Northern and Southern
hemisphere observatories are found separately, and are tested for global
consistency based on common fields near the celestial equator.
Several results from the GPC are presented, including establishing candidate
secondary standards, monitoring of near-infrared atmospheric extinction
coefficients, and verification of global validity of the standards. The
solution gives long-term averages of the atmospheric extinction coefficients,
A_J=0.096, A_H=0.026, A_{K_s}=0.066 (North) and A_J=0.092, A_H=0.031,
A_{K_s}=0.065 (South), with formal error of 0.001. The residuals show small
seasonal variations, most likely due to changing atmospheric content of water
vapor. Extension of the GPC to approximately 100 field stars in each of the 35
calibration fields yields a catalog of more than two thousand photometric
standards ranging from 10th to 14th magnitude, with photometry that is globally
consistent to .Comment: 19 pages, 10 figures; Submitted to AJ. The table of secondary
standards is available from ftp://nova.astro.umass.edu/pub/nikolaev/ or
ftp://anon-ftp.ipac.caltech.edu/pub/2mass/globalcal
Training to Be an Early Childhood Professional: Teacher Candidatesâ Perceptions about Their Education and Training
Professionalism in the context of early care and education has received considerable attention in recent years (Caulfield, 1997; Harte, 2011; Tigistu, 2013). According to the 2010 National Association for the Education of Young Children (NAEYC) Standards for Initial & Advanced Early Childhood Professional Preparation Programs, teacher candidates prepared in early childhood degree programs should identify and conduct themselves as members of the profession, know and use ethical guidelines and utilize other professional standards related to early childhood practice (NAEYC, 2012). In their final journal entry for a student teaching practicum course, teacher candidates in an accredited early childhood program reflected on what it means to be an early childhood professional. In alignment with the 2010 NAEYC Standards, teacher candidates appeared to recognize that being an early childhood professional means having an understanding of the specialized knowledge required to be effective in early childhood education. They also appeared to be aware that providing responsive, supportive curricula, which acknowledges and respects the whole child and family and their cultural backgrounds, is an integral aspect of the early childhood profession. Implications from this inquiry suggest that the early childhood program should ensure the fidelity to the NAEYC Standards by aligning assignments that incorporate the language and expectations of the Standards
Biofilm formation is a risk factor for mortality in patients with Candida albicans bloodstream infection-Scotland, 2012-2013
Acknowledgements This work was supported by the Wellcome Trust Strategic Award for Medical Mycology and Fungal Immunology 097377/Z/11/Z. Data collection was supported by a grant from Pfizer. G. Ramage was also supported by a research fellowship grant from Gilead Sciences. We are grateful to microbiology colleagues throughout Scotland for submitting isolates.Peer reviewedPublisher PD
Constraints on Higher-Order Perturbative Corrections in Semileptonic Decays from Residual Renormalization-Scale Dependence
The constraint of a progressive decrease in residual renormalization scale
dependence with increasing loop order is developed as a method for obtaining
bounds on unknown higher-order perturbative corrections to
renormalization-group invariant quantities. This technique is applied to the
inclusive semileptonic process (explicitly known to
two-loop order) to obtain bounds on the three- and four-loop perturbative
coefficients that are not accessible via the renormalization group. Using the
principle of minimal sensitivity, an estimate is obtained for the perturbative
contributions to that incorporates
theoretical uncertainty from as-yet-undetermined higher order QCD corrections.Comment: latex2e using amsmath, 8 pages, 4 embedded eps figures. Revised
version contains an additional figure and accompanying revision
Training older adults to use automatic teller machines.
The present study assessed the success of several instructional programs in teaching the use of automatic teller machines (ATMs). Fifty-six older adults (aged 61 to 81) participated in the study, randomly assigned to each of four, 14-member groups. The description group received only a general overview of an ATM; the text guide group received written instructions for performing various transactions on an ATM; the pictorial guide group received written instructions accompanied by pictures of corresponding ATM screens; and the online tutorial group completed a step-by-step tutorial on a simulated ATM. Participants practiced on an ATM simulator. They were tested after a 24-h interval on their ability to perform familiar transactions on an unfamiliar ATM simulator and to perform completely novel transactions. Accuracy was best for the online tutorial group, intermediate for the text and pictorial guide groups, and worst for the description group. These data demonstrate both the importance of providing older adults with ATM training and the fact that the type of training influences the level of performance. The online tutorial, which provided specific practice on the task components, best facilitated acquisition and transfer performance
Candida albicans biofilm heterogeneity does not influence denture stomatitis but strongly influences denture cleansing capacity
Approximately 20 â% of the UK population wear some form of denture prosthesis, resulting in denture stomatitis in half of these individuals. Candida albicans is primarily attributed as the causative agent, due to its biofilm -forming ability. Recently, there has been increasing evidence of C. albicans biofilm heterogeneity and the negative impact it can have clinically; however, this phenomenon has yet to be studied in relation to denture isolates. The aims of this study were to evaluate C. albicans biofilm formation of clinical denture isolates in a denture environment and to assess antimicrobial activity of common denture cleansers against these tenacious communities. C. albicans isolated from dentures of healthy and diseased individuals was quantified using real-time PCR and biofilm biomass assessed using crystal violet. Biofilm development on the denture substratum poly(methyl methacrylate), Molloplast B and Ufi-gel was determined. Biofilm formation was assessed using metabolic and biomass stains, following treatment with denture hygiene products. Although C. albicans was detected in greater quantities in diseased individuals, it was not associated with increased biofilm biomass. Denture substrata were shown to influence biofilm biomass, with poly(methyl methacrylate) providing the most suitable environment for C. albicans to reside. Of all denture hygiene products tested, Milton had the most effective antimicrobial activity, reducing biofilm biomass and viability the greatest. Overall, our results highlight the complex nature of denture- related disease, and disease development cannot always be attributed to a sole cause. It is the distinct combination of various factors that ultimately determines the pathogenic outcome
Structure-preserving deep learning
Over the past few years, deep learning has risen to the foreground as a topic
of massive interest, mainly as a result of successes obtained in solving
large-scale image processing tasks. There are multiple challenging mathematical
problems involved in applying deep learning: most deep learning methods require
the solution of hard optimisation problems, and a good understanding of the
tradeoff between computational effort, amount of data and model complexity is
required to successfully design a deep learning approach for a given problem. A
large amount of progress made in deep learning has been based on heuristic
explorations, but there is a growing effort to mathematically understand the
structure in existing deep learning methods and to systematically design new
deep learning methods to preserve certain types of structure in deep learning.
In this article, we review a number of these directions: some deep neural
networks can be understood as discretisations of dynamical systems, neural
networks can be designed to have desirable properties such as invertibility or
group equivariance, and new algorithmic frameworks based on conformal
Hamiltonian systems and Riemannian manifolds to solve the optimisation problems
have been proposed. We conclude our review of each of these topics by
discussing some open problems that we consider to be interesting directions for
future research
The CO Molecular Outflows of IRAS 16293-2422 Probed by the Submillimeter Array
We have mapped the proto-binary source IRAS 16293-2422 in CO 2-1, 13CO 2-1,
and CO 3-2 with the Submillimeter Array (SMA). The maps with resolution of
1".5-5" reveal a single small scale (~3000 AU) bipolar molecular outflow along
the east-west direction. We found that the blueshifted emission of this small
scale outflow mainly extends to the east and the redshifted emission to the
west from the position of IRAS 16293A. A comparison with the morphology of the
large scale outflows previously observed by single-dish telescopes at
millimeter wavelengths suggests that the small scale outflow may be the inner
part of the large scale (~15000 AU) E-W outflow. On the other hand, there is no
clear counterpart of the large scale NE-SW outflow in our SMA maps. Comparing
analytical models to the data suggests that the morphology and kinematics of
the small scale outflow can be explained by a wide-angle wind with an
inclination angle of ~30-40 degrees with respect to the plane of the sky. The
high resolution CO maps show that there are two compact, bright spots in the
blueshifted velocity range. An LVG analysis shows that the one located 1" to
the east of source A is extremely dense, n(H_2)~10^7 cm^-3, and warm, T_kin >55
K. The other one located 1" southeast of source B has a higher temperature of
T_kin >65 K but slightly lower density of n(H_2)~10^6 cm^-3. It is likely that
these bright spots are associated with the hot core-like emission observed
toward IRAS 16293. Since both two bright spots are blueshifted from the
systemic velocity and are offset from the protostellar positions, they are
likely formed by shocks.Comment: 27 pages, 8 figures, accepted for publication in ApJ, minor typos
correcte
Observations of Binary Stars with the Differential Speckle Survey Instrument. VII. Measures from 2010 September to 2012 February at the WIYN Telescope
We report on speckle observations of binary stars carried out at the WIYN
Telescope over the period from September 2010 through February 2012, providing
relative astrometry for 2521 observations of 883 objects, 856 of which are
double stars and 27 of which are triples. The separations measured span a range
of 0.01 to 1.75 arc seconds. Wavelengths of 562 nm, 692 nm, and 880 nm were
used, and differential photometry at one or more of these wavelengths is
presented in most cases. Sixty-six components were resolved for the first time.
We also estimate detection limits at 0.2 and 1.0 arc seconds for high-quality
observations in cases where no companion was seen, a total of 176 additional
objects. Detection limits vary based on observing conditions and
signal-to-noise ratio, but are approximately 4 magnitudes at 0.2 arc seconds
and 6 magnitudes at 1.0 arc seconds on average. Analyzing the measurement
precision of the data set, we find that the individual separations obtained
have linear measurement uncertainties of approximately 2 mas, and photometry is
uncertain to approximately 0.1 magnitudes in general. This work provides
fundamental, well-calibrated data for future orbit and mass determinations, and
we present three first orbits and total mass estimates of nearby K-dwarf
systems as examples of this potential
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