27,333 research outputs found
Quantifying critical thinking: Development and validation of the Physics Lab Inventory of Critical thinking (PLIC)
Introductory physics lab instruction is undergoing a transformation, with
increasing emphasis on developing experimentation and critical thinking skills.
These changes present a need for standardized assessment instruments to
determine the degree to which students develop these skills through
instructional labs. In this article, we present the development and validation
of the Physics Lab Inventory of Critical thinking (PLIC). We define critical
thinking as the ability to use data and evidence to decide what to trust and
what to do. The PLIC is a 10-question, closed-response assessment that probes
student critical thinking skills in the context of physics experimentation.
Using interviews and data from 5584 students at 29 institutions, we
demonstrate, through qualitative and quantitative means, the validity and
reliability of the instrument at measuring student critical thinking skills.
This establishes a valuable new assessment instrument for instructional labs.Comment: 16 pages, 4 figure
Exosuit-induced improvements in walking after stroke: comprehensive analysis on gait energetics and biomechanics
Outstanding Poster Presentation Finalis
New ammonia masers towards NGC6334I
We report the detection of new ammonia masers in the non-metastable (8,6) and
(11,9) transitions towards the massive star forming region NGC6334I.
Observations were made with the ATCA interferometer and the emitting region
appears unresolved in the 2.7" x 0.8" beam, with deconvolved sizes less than an
arcsecond. We estimate peak brightness temperatures of 7.8 x 10^5 and 1.2 x
10^5 K for the (8,6) and (11,9) transitions, respectively. The masers appear
coincident both spatially and in velocity with a previously detected ammonia
(6,6) maser. We also suggest that emission in the (10,9), (9,9) and (7,6)
transitions may also be masers, based on their narrow line widths and
overlapping velocity ranges with the above masers, as observed with the
single-dish Mopra radiotelescope
Stochastic theory of large-scale enzyme-reaction networks: Finite copy number corrections to rate equation models
Chemical reactions inside cells occur in compartment volumes in the range of
atto- to femtolitres. Physiological concentrations realized in such small
volumes imply low copy numbers of interacting molecules with the consequence of
considerable fluctuations in the concentrations. In contrast, rate equation
models are based on the implicit assumption of infinitely large numbers of
interacting molecules, or equivalently, that reactions occur in infinite
volumes at constant macroscopic concentrations. In this article we compute the
finite-volume corrections (or equivalently the finite copy number corrections)
to the solutions of the rate equations for chemical reaction networks composed
of arbitrarily large numbers of enzyme-catalyzed reactions which are confined
inside a small sub-cellular compartment. This is achieved by applying a
mesoscopic version of the quasi-steady state assumption to the exact
Fokker-Planck equation associated with the Poisson Representation of the
chemical master equation. The procedure yields impressively simple and compact
expressions for the finite-volume corrections. We prove that the predictions of
the rate equations will always underestimate the actual steady-state substrate
concentrations for an enzyme-reaction network confined in a small volume. In
particular we show that the finite-volume corrections increase with decreasing
sub-cellular volume, decreasing Michaelis-Menten constants and increasing
enzyme saturation. The magnitude of the corrections depends sensitively on the
topology of the network. The predictions of the theory are shown to be in
excellent agreement with stochastic simulations for two types of networks
typically associated with protein methylation and metabolism.Comment: 13 pages, 4 figures; published in The Journal of Chemical Physic
Emission-Line Galaxies from the HST PEARS Grism Survey I: The South Fields
We present results of a search for emission-line galaxies in the Southern
Fields of the Hubble Space Telescope PEARS (Probing Evolution And Reionization
Spectroscopically) grism survey. The PEARS South Fields consist of five ACS
pointings (including the Hubble Ultra Deep Field) with the G800L grism for a
total of 120 orbits, revealing thousands of faint object spectra in the
GOODS-South region of the sky. Emission-line galaxies (ELGs) are one subset of
objects that are prevalent among the grism spectra. Using a 2-dimensional
detection and extraction procedure, we find 320 emission lines orginating from
226 galaxy "knots'' within 192 individual galaxies. Line identification results
in 118 new grism-spectroscopic redshifts for galaxies in the GOODS-South Field.
We measure emission line fluxes using standard Gaussian fitting techniques. At
the resolution of the grism data, the H-beta and [OIII] doublet are blended.
However, by fitting two Gaussian components to the H-beta and [OIII] features,
we find that many of the PEARS ELGs have high [OIII]/H-beta ratios compared to
other galaxy samples of comparable luminosities. The star-formation rates
(SFRs) of the ELGs are presented, as well as a sample of distinct giant
star-forming regions at z~0.1-0.5 across individual galaxies. We find that the
radial distances of these HII regions in general reside near the galaxies'
optical continuum half-light radii, similar to those of giant HII regions in
local galaxies.Comment: 15 pages, 13 figures; Accepted for publication in A
Stars in the Hubble Ultra Deep Field
We identified 46 unresolved source candidates in the Hubble Ultra Deep Field,
down to i775 = 29.5. Unresolved objects were identified using a parameter S,
which measures the deviation from the curve-of-growth of a point source.
Extensive testing of this parameter was carried out, including the effects of
decreasing signal-to-noise and of the apparent motions of stars, which
demonstrated that stars brighter than i775 = 27.0 could be robustly identified.
Low resolution grism spectra of the 28 objects brighter than i775 = 27.0
identify 18 M and later stellar type dwarfs, 2 candidate L-dwarfs, 2 QSOs, and
4 white dwarfs. Using the observed population of dwarfs with spectral type M4
or later, we derive a Galactic disk scale height of 400 \pm 100 pc for M and L
stars. The local white dwarf density is computed to be as high as (1.1 \pm 0.3)
x10^(-2) stars/pc^3. Based on observations taken 73 days apart, we determined
that no object in the field has a proper motion larger than 0.027"/year (3
sigma detection limit). No high velocity white dwarfs were identified in the
HUDF, and all four candidates appear more likely to be part of the Galactic
thick disk. The lack of detected halo white dwarfs implies that, if the dark
matter halo is 12 Gyr old, white dwarfs account for less than 10% of the dark
matter halo mass.Comment: 35 pages, 11 figures, accepted by Ap
High frequency sampling of the 1984 spring bloom within the mid-Atlantic Bight: Synoptic shipboard, aircraft, and in situ perspectives of the SEEP-I experiment
Moorings of current meters, thermistors, transmissometers, and fluorometers on the mid-Atlantic shelf, south of Long Island, suggest a cumulative seaward export of perhaps 0.35 g C/sq m/day between the 80 and 120 m isobaths during February-April 1984. Such a horizontal loss of algal carbon over the lower third of the water column would be 23 to 78% of the March-April 1984 primary production. This physical carbon loss is similar to daily grazing losses from zooplankton of 32-40% of the algal fixation of carbon. Metabolic demands of the benthos could be met by just the estimated fecal pellet flux, without direct consumption of algal carbon, while bacterioplankton needs could be served by excretory release of dissolved organic matter during photosynthesis. Sediment traps tethered 10 m off the bottom at the 120 m isobath and 50 m above the 500 m isobath caught as much as 0.16 to 0.26 g C /sq m/day during March-April 1984, in reasonable agreement with the flux estimated from the other moored instruments
Using a Clean Feedback Model to Facilitate the Learning Process
Effective and informative feedback is an essential part of learning and improving performance that is influenced by a number of issues, such as time constraints, ambiguous communication and emotional barriers (Hattie, 1998). Feedback should facilitate the learning process and the teaching performance. Accordingly, in this article we examine the “clean feedback” model developed by Walker and Doyle (2006) and explore its impact on the learning experiences of a purposeful sample of eleven beginning physical education teachers undertaking a one year postgraduate Qualified Teacher Status course at a post-92 university in the North West of England. After two days of staff and student training in using the model, the data in the form of lesson evaluations and self feed- back were collected at staged time intervals during their second placement school. The findings indicate that the model has improved the students’ ability to give and receive both positive and negative feedback and to improve students self awareness and understanding of their own learning and teaching styles. The implications of our findings are discussed in relation to the observation and feedback of the beginning teachers and mentors might be improved on such courses for physical education trainee teachers
GP experience and understandings of providing follow‐up care in prostate cancer survivors in England
Survival times for prostate cancer have increased substantially, meaning more survivors will be discharged to General Practitioners' (GP) services. The detection of recurrence and monitoring of symptoms and long‐term side‐effects in prostate cancer survivors requires the active involvement of GPs in their follow‐up care. In order to address this, the transition and discharge from hospital to primary care must be managed effectively. The objective of this study was to examine the preparedness, concerns and experiences of GPs in relation to their role in providing follow‐up care to prostate cancer survivors. Purposive sampling was used to recruit GPs with experience in providing care to prostate cancer survivors. Twenty semi‐structured telephone interviews were conducted with GPs across England. The interviews were audio‐recorded, transcribed verbatim and analysed using thematic analysis. Participants described their current role in the follow‐up pathway, a number of challenges and barriers in assuming this role, and potential ways to resolve these and improve their involvement. They expressed a range of views about their preparedness and willingness to take over follow‐up care after discharge for this group of patients. GPs had reservations about workload, lack of resources, expertise and deficiencies in communication with hospitals. Findings from this study suggest that GPs will be ready to take over the follow‐up care of prostate cancer survivors if better information, additional training and adequate resources are provided and communication lines with hospital specialists are clear. Understanding the issues faced by GPs and overcoming identified barriers to providing follow‐up care to prostate cancer survivors will provide the insight necessary to make the process of transferring care from secondary to primary teams a more straightforward task for all stakeholders
VLASSICK: The VLA Sky Survey in the Central Kiloparsec
At a distance of 8 kpc, the center of our Galaxy is the nearest galactic
nucleus, and has been the subject of numerous key projects undertaken by great
observatories such as Chandra, Spitzer, and Herschel. However, there are still
no surveys of molecular gas properties in the Galactic center with less than
30" (1 pc) resolution. There is also no sensitive polarization survey of this
region, despite numerous nonthermal magnetic features apparently unique to the
central 300 parsecs. In this paper, we outline the potential the VLASS has to
fill this gap. We assess multiple considerations in observing the Galactic
center, and recommend a C-band survey with 10 micro-Jy continuum RMS and
sensitive to molecular gas with densities greater than 10^4 cm^{-3}, covering
17 square degrees in both DnC and CnB configurations ( resolution ~5"),
totaling 750 hours of observing time. Ultimately, we wish to note that the
upgraded VLA is not just optimized for fast continuum surveys, but has a
powerful correlator capable of simultaneously observing continuum emission and
dozens of molecular and recombination lines. This is an enormous strength that
should be fully exploited and highlighted by the VLASS, and which is ideally
suited for surveying the center of our Galaxy.Comment: 13 pages, 3 figures, a White Paper submitted to provide input in
planning the Very Large Array Sky Surve
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