3,418 research outputs found
Listening to the New Student Voice: How They Learn
In 2003 it was forecasted that medical studentsâpreclinical learning would mostly consist of large portions of educational training and instruction provided on the internet and other technology tools, while the traditional lecture format would become more infrequent. Five years later many medical schools have adapted to this new technological-enhanced learning environment.
No one can argue that todayâs millennial generation of medical students is more familiar with technology than their predecessors. However, does this technology savvy generation report that these new tools are indeed superior when compared to the traditional tools of facilitating learning and understanding in the preclinical years? Additionally, is there a difference in usefulness of learning techniques for students in year one as compared to year two of medical school?
This study examines the learning tools in basic science courses to determine how the millennial generation of students report they are learning best. Tools from our blended learning curriculum were investigated within and across preclinical years one and two.
Presented at the AAMC (Association of American Colleges) Annual Meeting, RIME (Research in Medical Education) Program, November 2008
Regularized orbit models unveiling the stellar structure and dark matter halo of the Coma elliptical NGC 4807
This is the second in a series of papers dedicated to unveil the mass
structure and orbital content of a sample of flattened early-type galaxies in
the Coma cluster. The ability of our orbit libraries to reconstruct internal
stellar motions and the mass composition of a typical elliptical in the sample
is investigated by means of Monte-Carlo simulations of isotropic rotator
models. The simulations allow a determination of the optimal amount of
regularization needed in the orbit superpositions. It is shown that under
realistic observational conditions and with the appropriate regularization
internal velocity moments can be reconstructed to an accuracy of about 15 per
cent; the same accuracy can be achieved for the circular velocity and dark
matter fraction. In contrast, the flattening of the halo remains unconstrained.
Regularized orbit superpositions are applied to a first galaxy in our sample,
NGC 4807, for which stellar kinematical observations extend to 3 Reff. The
galaxy seems dark matter dominated outside 2 Reff. Logarithmic dark matter
potentials are consistent with the data, as well as NFW-profiles, mimicking
logarithmic potentials over the observationally sampled radial range. In both
cases, the derived stellar mass-to-light ratio agrees well with independently
obtained mass-to-light ratios from stellar population analysis. Kinematically,
NGC 4807 is characterized by mild radial anisotropy outside r>0.5 Reff,
becoming isotropic towards the center. Our orbit models hint at either a
distinct stellar component or weak triaxiality in the outer parts of the
galaxy.Comment: 20 pages, 25 figures, accepted for publication in MNRA
Tumor Necrosis Factor - Related Apoptosis-Inducing Ligand (TRAIL) promotes angiogenesis and ischemia- induced neovascularization via NADPH Oxidase 4 (NOX4) and Nitric Oxide - dependent mechanisms
Background â Tumor necrosis factorârelated apoptosis-inducing ligand (TRAIL) has the ability to inhibit angiogenesis by inducing endothelial cell death, as well as being able to promote pro- angiogenic activity in vitro. These seemingly opposite effects make its role in ischemic disease unclear. Using Trail_/_ and wildtype mice, we sought to determine the role of TRAIL in angiogenesis and neovascularization following hindlimb ischemia.
Methods and Results â Reduced vascularization assessed by real-time 3-dimensional Vevo ultrasound imaging and CD31 staining was evident in Trail_/_ mice after ischemia, and associated with reduced capillary formation and increased apoptosis. Notably, adenoviral TRAIL administration significantly improved limb perfusion, capillary density, and vascular smooth-muscle cell content in both Trail_/_ and wildtype mice. Fibroblast growth factor-2, a potent angiogenic factor, increased TRAIL expression in human microvascular endothelial cell-1, with fibroblast growth factor-2-mediated proliferation, migration, and tubule formation inhibited with TRAIL siRNA. Both fibroblast growth factor-2 and TRAIL significantly increased NADPH oxidase 4 (NOX4) expression. TRAIL-inducible angiogenic activity in vitro was inhibited with siRNAs targeting NOX4, and consistent with this, NOX4 mRNA was reduced in 3-day ischemic hindlimbs of Trail_/_ mice. Furthermore, TRAIL-induced proliferation, migration, and tubule formation was blocked by scavenging H2O2, or by inhibiting nitric oxide synthase activity. Importantly, TRAIL-inducible endothelial nitric oxide synthase phosphorylation at Ser-1177 and intracellular human microvascular endothelial cell-1 cell nitric oxide levels were NOX4 dependent.
Conclusions â This is the first report demonstrating that TRAIL can promote angiogenesis following hindlimb ischemia in vivo. The angiogenic effect of TRAIL on human microvascular endothelial cell-1 cells is downstream of fibroblast growth factor-2, involving NOX4 and nitric oxide signaling. These data have significant therapeutic implications, such that TRAIL may improve the angiogenic response to ischemia and increase perfusion recovery in patients with cardiovascular disease and diabetes
Point-of-care testing for disasters: needs assessment, strategic planning, and future design.
Objective evidence-based national surveys serve as a first step in identifying suitable point-of-care device designs, effective test clusters, and environmental operating conditions. Preliminary survey results show the need for point-of-care testing (POCT) devices using test clusters that specifically detect pathogens found in disaster scenarios. Hurricane Katrina, the tsunami in southeast Asia, and the current influenza pandemic (H1N1, "swine flu") vividly illustrate lack of national and global preparedness. Gap analysis of current POCT devices versus survey results reveals how POCT needs can be fulfilled. Future thinking will help avoid the worst consequences of disasters on the horizon, such as extensively drug-resistant tuberculosis and pandemic influenzas. A global effort must be made to improve POC technologies to rapidly diagnose and treat patients to improve triaging, on-site decision making, and, ultimately, economic and medical outcomes
The conceptualisation and measurement of DSM-5 Internet Gaming Disorder: the development of the IGD-20 Test
Background: Over the last decade, there has been growing concern about âgaming addictionâ and its widely documented detrimental impacts on a minority of individuals that play excessively. The latest (fifth) edition of the American Psychiatric Associationâs Diagnostic and Statistical Manual of Mental Disorders (DSM-5) included nine criteria for the potential diagnosis of Internet Gaming Disorder (IGD) and noted that it was a condition that warranted further empirical study. Aim: The main aim of this study was to develop a valid and reliable standardised psychometrically robust tool in addition to providing empirically supported cut-off points. Methods: A sample of 1003 gamers (85.2% males; mean age 26 years) from 57 different countries were recruited via online gaming forums. Validity was assessed by confirmatory factor analysis (CFA), criterion-related validity, and concurrent validity. Latent profile analysis was also carried to distinguish disordered gamers from non-disordered gamers. Sensitivity and specificity analyses were performed to determine an empirical cut-off for the test. Results: The CFA confirmed the viability of IGD-20 Test with a six-factor structure (salience, mood modification, tolerance, withdrawal, conflict and relapse) for the assessment of IGD according to the nine criteria from DSM-5. The IGD-20 Test proved to be valid and reliable. According to the latent profile analysis, 5.3% of the total participants were classed as disordered gamers. Additionally, an optimal empirical cut-off of 71 points (out of 100) seemed to be adequate according to the sensitivity and specificity analyses carried
Polytropic dark halos of elliptical galaxies
The kinematics of stars and planetary nebulae in early type galaxies provide
vital clues to the enigmatic physics of their dark matter halos. We fit
published data for fourteen such galaxies using a spherical, self-gravitating
model with two components: (1) a Sersic stellar profile fixed according to
photometric parameters, and (2) a polytropic dark matter halo that conforms
consistently to the shared gravitational potential. The polytropic equation of
state can describe extended theories of dark matter involving self-interaction,
non-extensive thermostatistics, or boson condensation (in a classical limit).
In such models, the flat-cored mass profiles widely observed in disc galaxies
are due to innate dark physics, regardless of any baryonic agitation. One of
the natural parameters of this scenario is the number of effective thermal
degrees of freedom of dark matter (F_d) which is proportional to the dark heat
capacity. By default we assume a cosmic ratio of baryonic and dark mass.
Non-Sersic kinematic ideosyncrasies and possible non-sphericity thwart fitting
in some cases. In all fourteen galaxies the fit with a polytropic dark halo
improves or at least gives similar fits to the velocity dispersion profile,
compared to a stars-only model. The good halo fits usually prefer F_d values
from six to eight. This range complements the recently inferred limit of
7<F_d<10 (Saxton & Wu), derived from constraints on galaxy cluster core radii
and black hole masses. However a degeneracy remains: radial orbital anisotropy
or a depleted dark mass fraction could shift our models' preference towards
lower F_d; whereas a loss of baryons would favour higher F_d.Comment: 17 pages, 10 figures, 2 tables. MNRAS accepte
The PN.S Elliptical Galaxy Survey: the dark matter in NGC 4494
We present new Planetary Nebula Spectrograph observations of the ordinary
elliptical galaxy NGC 4494, resulting in positions and velocities of 255 PNe
out to 7 effective radii (25 kpc). We also present new wide-field surface
photometry from MMT/Megacam, and long-slit stellar kinematics from VLT/FORS2.
The spatial and kinematical distributions of the PNe agree with the field stars
in the region of overlap. The mean rotation is relatively low, with a possible
kinematic axis twist outside 1 Re. The velocity dispersion profile declines
with radius, though not very steeply, down to ~70 km/s at the last data point.
We have constructed spherical dynamical models of the system, including Jeans
analyses with multi-component LCDM-motivated galaxies as well as logarithmic
potentials. These models include special attention to orbital anisotropy, which
we constrain using fourth-order velocity moments. Given several different sets
of modelling methods and assumptions, we find consistent results for the mass
profile within the radial range constrained by the data. Some dark matter (DM)
is required by the data; our best-fit solution has a radially anisotropic
stellar halo, a plausible stellar mass-to-light ratio, and a DM halo with an
unexpectedly low central density. We find that this result does not
substantially change with a flattened axisymmetric model.
Taken together with other results for galaxy halo masses, we find suggestions
for a puzzling pattern wherein most intermediate-luminosity galaxies have very
low concentration halos, while some high-mass ellipticals have very high
concentrations. We discuss some possible implications of these results for DM
and galaxy formation.Comment: 29 pages, 17 figures. MNRAS, accepte
The PN.S Elliptical Galaxy Survey: a standard LCDM halo around NGC 4374?
As part of our current programme to test LCDM predictions for dark matter
(DM) haloes using extended kinematical observations of early-type galaxies, we
present a dynamical analysis of the bright elliptical galaxy NGC 4374 (M84)
based on ~450 Planetary Nebulae (PNe) velocities from the PN.Spectrograph,
along with extended long-slit stellar kinematics. This is the first such
analysis of a galaxy from our survey with a radially constant velocity
dispersion profile. We find that the spatial and kinematical distributions of
the PNe agree with the field stars in the region of overlap. The velocity
kurtosis is consistent with zero at almost all radii. We construct a series of
Jeans models, fitting both velocity dispersion and kurtosis to help break the
mass-anisotropy degeneracy. Our mass models include DM halos either with
shallow cores or with central cusps as predicted by cosmological simulations -
along with the novel introduction in this context of adiabatic halo contraction
from baryon infall. Both classes of models confirm a very massive dark halo
around NGC 4374, demonstrating that PN kinematics data are well able to detect
such haloes when present. Considering the default cosmological mass model, we
confirm earlier suggestions that bright galaxies tend to have halo
concentrations higher than LCDM predictions, but this is found to be solved if
either a Salpeter IMF or adiabatic contraction with a Kroupa IMF is assumed.
Thus for the first time a case is found where the PN dynamics may well be
consistent with a standard dark matter halo. A cored halo can also fit the
data, and prefers a stellar mass consistent with a Salpeter IMF. The less
dramatic dark matter content found in lower-luminosity "ordinary" ellipticals
suggests a bimodality in the halo properties which may be produced by divergent
baryonic effects during their assembly histories.Comment: 22 pages, 14 figures. MNRAS, accepte
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