4,004 research outputs found
Chiral effective field theory beyond the power-counting regime
Novel techniques are presented, which identify the chiral power-counting
regime (PCR), and realize the existence of an intrinsic energy scale embedded
in lattice QCD results that extend outside the PCR. The nucleon mass is
considered as a benchmark for illustrating this new approach. Using
finite-range regularization, an optimal regularization scale can be extracted
from lattice simulation results by analyzing the renormalization of the low
energy coefficients. The optimal scale allows a description of lattice
simulation results that extend beyond the PCR by quantifying and thus handling
any scheme-dependence. Preliminary results for the nucleon magnetic moment are
also examined, and a consistent optimal regularization scale is obtained. This
indicates the existence of an intrinsic scale corresponding to the finite size
of the source of the pion cloud.Comment: 6 pages, 4 figures, conferenc
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Much to do about identity: Successful women in science reflect on their school years
This study presents the recollections of 12 successful women in science duringtheir school years before postsecondary education. The participants shareddetailed descriptions of their science experiences through three semi-structured interviews. An identity works conceptual framework consisting offigured worlds, positioning, and agency constructs to portray the complexdynamics of their experiences was used to analyze the data. The following fourthemes emerged from the data analysis: participants had an early interest inmathematics and science; they were“stubbornly”persistent in science-figuredworlds; they engaged in science-figured worlds beyond school; and they posi-tioned themselves as science leaders. These findings add to the evolution of sci-ence identity development theoretical models because they are from anondeficit perspective. Participants engaged in identity work that advancedtheir science identities despite the gender biases in science-figured worlds.From a practical stance, girls and women could employ the agentic and posi-tive positioning identity work that the findings show to develop their scienceidentity in educational contexts. Science educators and researchers are encour-aged to structure figured worlds where girls feel empowered to enact identitywork to build strong science identities
Time-Series Ensemble Photometry and the Search for Variable Stars in the Open Cluster M11
This work presents the first large-scale photometric variability survey of
the intermediate age (~200 Myr) open cluster M11. Thirteen nights of data over
two observing seasons were analyzed (using crowded field and ensemble
photometry techniques) to obtain high relative precision photometry. In this
study we focus on the detection of candidate member variable stars for
follow-up studies. A total of 39 variable stars were detected and can be
categorized as follows: 1 irregular (probably pulsating) variable, 6 delta
Scuti variables, 14 detached eclipsing binary systems, 17 W UMa variables, and
1 unidentified/candidate variable. While previous proper motion studies allow
for cluster membership determination for the brightest stars, we find that
membership determination is significantly hampered below V=15,R=15.5 by the
large population of field stars overlapping the cluster MS. Of the brightest
detected variables that have a high likelihood of cluster membership, we find
five systems where further work could help constrain theoretical stellar
models, including one potential W UMa member of this young cluster.Comment: 38 pages, 13 figures, accepted for December 2005 AJ, high-resolution
version available upon reques
Motivating Reluctant Learners with a Big Bang
We present results of a collaboration between a media specialist, a science teacher, and an astronomer to bring a modern astronomy topic to at-risk, emotionally disabled students who have experienced little success. These normally unengaged students became highly motivated because they were given an authentic task of presenting research on an intriguing science topic, and because they witnessed a collaboration brought together on their behalf This experience demonstrates that sophisticated astronomy topics can be used to motivate at-risk students
Lattice QCD Evidence that the Lambda(1405) Resonance is an Antikaon-Nucleon Molecule
For almost 50 years the structure of the Lambda(1405) resonance has been a
mystery. Even though it contains a heavy strange quark and has odd parity, its
mass is lower than any other excited spin-1/2 baryon. Dalitz and co-workers
speculated that it might be a molecular state of an antikaon bound to a
nucleon. However, a standard quark-model structure is also admissible. Although
the intervening years have seen considerable effort, there has been no
convincing resolution. Here we present a new lattice QCD simulation showing
that the strange magnetic form factor of the Lambda(1405) vanishes, signaling
the formation of an antikaon-nucleon molecule. Together with a Hamiltonian
effective-field-theory model analysis of the lattice QCD energy levels, this
strongly suggests that the structure is dominated by a bound antikaon-nucleon
component. This result clarifies that not all states occurring in nature can be
described within a simple quark model framework and points to the existence of
exotic molecular meson-nucleon bound states.Comment: Manuscript accepted for publication. 4 figures, 5 page
Comparison of Supine and Vertical Bioimpedance Measurements in Young Adults
Topics in Exercise Science and Kinesiology Volume 3: Issue 1, Article 11, 2022. Bioelectrical impedance analysis (BIA) methods estimate health parameters such as phase angle (PhA) and body fat percentage (%BF) from various positional and electrode configurations. PhA and %BF are known biological markers of cellular and physical health, respectively, and can be used to predict various health-related conditions and therefore require accurate assessment. The purpose of this study was to evaluate the effect of body position during BIA by investigating the difference and agreement between PhA and %BF using RJL (supine) and InBody (vertical) analyzers. Thirty-eight young adults (23.4±4.1 yrs.) volunteered and underwent body composition assessments by both analyzers. Difference and agreement in assessments of PhA and %BF between analyzers were assessed using paired samples t-tests and Lin’s concordance correlation coefficient (rc), respectively. RJL’s PhA (7.15±0.84°) exceeded InBody’s (6.11±0.74°), p\u3c0.001, and had poor agreement (rc =0.47). RJL’s %BF (23.0±6.8%) was similar to InBody’s (23.1±7.4%), p=0.813, and had substantial agreement (rc =0.95). Both analyzers estimated %BF similarly and may be interchangeable for this purpose, thus demonstrating no effect of body position on the estimation of %BF with these BIA devices. An individual\u27s PhA may be underestimated if measured in the vertical position and compared to supine reference values. Current reference values for PhA are based on measurements in the supine position, so until vertical reference values of PhA are available, caution is urged when interpreting PhA from vertical BIA assessments
Measurement of Volumetric Flow
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135278/1/jum200625101305.pd
The Sloan Digital Sky Survey Reverberation Mapping Project: Ensemble Spectroscopic Variability of Quasar Broad Emission Lines
We explore the variability of quasars in the MgII and Hbeta broad emission
lines and UV/optical continuum emission using the Sloan Digital Sky Survey
Reverberation Mapping project (SDSS-RM). This is the largest spectroscopic
study of quasar variability to date: our study includes 29 spectroscopic epochs
from SDSS-RM over months, containing 357 quasars with MgII and 41 quasars
with Hbeta . On longer timescales, the study is also supplemented with
two-epoch data from SDSS-I/II. The SDSS-I/II data include an additional
quasars with MgII and 572 quasars with Hbeta. The MgII emission line is
significantly variable ( 10% on 100-day timescales), a necessary
prerequisite for its use for reverberation mapping studies. The data also
confirm that continuum variability increases with timescale and decreases with
luminosity, and the continuum light curves are consistent with a damped
random-walk model on rest-frame timescales of days. We compare the
emission-line and continuum variability to investigate the structure of the
broad-line region. Broad-line variability shows a shallower increase with
timescale compared to the continuum emission, demonstrating that the broad-line
transfer function is not a -function. Hbeta is more variable than MgII
(roughly by a factor of ), suggesting different excitation mechanisms,
optical depths and/or geometrical configuration for each emission line. The
ensemble spectroscopic variability measurements enabled by the SDSS-RM project
have important consequences for future studies of reverberation mapping and
black hole mass estimation of quasars.Comment: 20 pages, 25 figures. ApJ accepted: minor revisions following referee
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