583 research outputs found
Master of Science
thesisAbnormal gait caused by stroke or other pathological reasons can greatly impact the life of an individual. Being able to measure and analyze that gait is often critical for rehabilitation. Motion analysis labs and many current methods of gait analysis are expensive and inaccessible to most individuals. The low cost, wearable, and wireless insole-based gait analysis system in this study provides kinetic measurements of gait by using low cost force sensitive resistors. This thesis describes the design and fabrication of two insoles and their evaluation with 10 control subjects and eight hemiplegic stroke subjects. The first insole used 32 force sensitive resistors and was used to determine the ideal locations of 12 sensors in the second insole. Linear regression was used on training data for each subject testing the second insole to determine ground reaction force, ankle dorsiflexion / plantarflexion moment, knee flexion / extension moment, and knee abduction / adduction moment. Comparison with data collected simultaneously from a clinical motion analysis laboratory demonstrated that the insole results for ground reaction force and ankle moment were highly correlated (all > 0.95) for all subjects, while the two knee moments were less strongly correlated (generally > 0.80). This provides a means of cost effective and efficient healthcare delivery of mobile gait analysis that can be used anywhere from large clinics to an individual's home. The two insoles also provide the means for further testing of force sensitive resistors in different applications
Force distributions in 3D granular assemblies: Effects of packing order and inter-particle friction
We present a systematic investigation of the distribution of normal forces at
the boundaries of static packings of spheres. A new method for the efficient
construction of large hexagonal-close-packed crystals is introduced and used to
study the effect of spatial ordering on the distribution of forces. Under
uniaxial compression we find that the form for the probability distribution of
normal forces between particles does not depend strongly on crystallinity or
inter-particle friction. In all cases the distribution decays exponentially at
large forces and shows a plateau or possibly a small peak near the average
force but does not tend to zero at small forces.Comment: 9 pages including 8 figure
CD32 is expressed on cells with transcriptionally active HIV but does not enrich for HIV DNA in resting T cells
The persistence of HIV reservoirs, including latently infected, resting CD4+ T cells, is the major obstacle to cure HIV infection. CD32a expression was recently reported to mark CD4+ T cells harboring a replication-competent HIV reservoir during antiretroviral therapy (ART) suppression. We aimed to determine whether CD32 expression marks HIV latently or transcriptionally active infected CD4+ T cells. Using peripheral blood and lymphoid tissue of ART-treated HIV+ or SIV+ subjects, we found that most of the circulating memory CD32+ CD4+ T cells expressed markers of activation, including CD69, HLA-DR, CD25, CD38, and Ki67, and bore a TH2 phenotype as defined by CXCR3, CCR4, and CCR6. CD32 expression did not selectively enrich for HIV- or SIV-infected CD4+ T cells in peripheral blood or lymphoid tissue; isolated CD32+ resting CD4+ T cells accounted for less than 3% of the total HIV DNA in CD4+ T cells. Cell-associated HIV DNA and RNA loads in CD4+ T cells positively correlated with the frequency of CD32+ CD69+ CD4+ T cells but not with CD32 expression on resting CD4+ T cells. Using RNA fluorescence in situ hybridization, CD32 coexpression with HIV RNA or p24 was detected after in vitro HIV infection (peripheral blood mononuclear cell and tissue) and in vivo within lymph node tissue from HIV-infected individuals. Together, these results indicate that CD32 is not a marker of resting CD4+ T cells or of enriched HIV DNA–positive cells after ART; rather, CD32 is predominately expressed on a subset of activated CD4+ T cells enriched for transcriptionally active HIV after long-term ART
Institutional Strategies to Achieve Diversity and Inclusion in Pharmacy Education
Objective. To evaluate the impact of institutional initiatives to enhance recruitment of minority students as a strategy to increase diversity and inclusion
Constraints on the Progenitor System of the Type Ia Supernova SN 2011fe/PTF11kly
Type Ia supernovae (SNe) serve as a fundamental pillar of modern cosmology,
owing to their large luminosity and a well-defined relationship between
light-curve shape and peak brightness. The precision distance measurements
enabled by SNe Ia first revealed the accelerating expansion of the universe,
now widely believed (though hardly understood) to require the presence of a
mysterious "dark" energy. General consensus holds that Type Ia SNe result from
thermonuclear explosions of a white dwarf (WD) in a binary system; however,
little is known of the precise nature of the companion star and the physical
properties of the progenitor system. Here we make use of extensive historical
imaging obtained at the location of SN 2011fe/PTF11kly, the closest SN Ia
discovered in the digital imaging era, to constrain the visible-light
luminosity of the progenitor to be 10-100 times fainter than previous limits on
other SN Ia progenitors. This directly rules out luminous red giants and the
vast majority of helium stars as the mass-donating companion to the exploding
white dwarf. Any evolved red companion must have been born with mass less than
3.5 times the mass of the Sun. These observations favour a scenario where the
exploding WD of SN 2011fe/PTF11kly, accreted matter either from another WD, or
by Roche-lobe overflow from a subgiant or main-sequence companion star.Comment: 22 pages, 6 figures, submitte
Fourteen Months of Observations of the Possible Super-Chandrasekhar Mass Type Ia Supernova 2009dc
In this paper, we present and analyse optical photometry and spectra of the
extremely luminous and slowly evolving Type Ia supernova (SN Ia) 2009dc, and
offer evidence that it is a super-Chandrasekhar mass (SC) SN Ia and thus had a
SC white dwarf (WD) progenitor. Optical spectra of SN 2007if, a similar object,
are also shown. SN 2009dc had one of the most slowly evolving light curves ever
observed for a SN Ia, with a rise time of ~23 days and Delta m_15(B) = 0.72
mag. We calculate a lower limit to the peak bolometric luminosity of ~2.4e43
erg/s, though the actual value is likely almost 40% larger. Optical spectra of
SN 2009dc and SN 2007if obtained near maximum brightness exhibit strong C II
features (indicative of a significant amount of unburned material), and the
post-maximum spectra are dominated by iron-group elements. All of our spectra
of SN 2009dc and SN 2007if also show low expansion velocities. However, we see
no strong evidence in SN 2009dc for a velocity "plateau" near maximum light
like the one seen in SN 2007if (Scalzo et al. 2010). The high luminosity and
low expansion velocities of SN 2009dc lead us to derive a possible WD
progenitor mass of more than 2 M_Sun and a Ni-56 mass of about 1.4-1.7 M_Sun.
We propose that the host galaxy of SN 2009dc underwent a gravitational
interaction with a neighboring galaxy in the relatively recent past. This may
have led to a sudden burst of star formation which could have produced the SC
WD progenitor of SN 2009dc and likely turned the neighboring galaxy into a
"post-starburst galaxy." No published model seems to match the extreme values
observed in SN 2009dc, but simulations do show that such massive progenitors
can exist (likely as a result of the merger of two WDs) and can possibly
explode as SC SNe Ia.Comment: 30 pages, 16 figures, 8 tables, re-submitted to MNRA
PTF10fqs: A Luminous Red Nova in the Spiral Galaxy Messier 99
The Palomar Transient Factory (PTF) is systematically charting the optical
transient and variable sky. A primary science driver of PTF is building a
complete inventory of transients in the local Universe (distance less than 200
Mpc). Here, we report the discovery of PTF10fqs, a transient in the luminosity
"gap" between novae and supernovae. Located on a spiral arm of Messier 99, PTF
10fqs has a peak luminosity of Mr = -12.3, red color (g-r = 1.0) and is slowly
evolving (decayed by 1 mag in 68 days). It has a spectrum dominated by
intermediate-width H (930 km/s) and narrow calcium emission lines. The
explosion signature (the light curve and spectra) is overall similar to thatof
M85OT2006-1, SN2008S, and NGC300OT. The origin of these events is shrouded in
mystery and controversy (and in some cases, in dust). PTF10fqs shows some
evidence of a broad feature (around 8600A) that may suggest very large
velocities (10,000 km/s) in this explosion. Ongoing surveys can be expected to
find a few such events per year. Sensitive spectroscopy, infrared monitoring
and statistics (e.g. disk versus bulge) will eventually make it possible for
astronomers to unravel the nature of these mysterious explosions.Comment: 12 pages, 12 figures, Replaced with published versio
The Relationship between Body Mass Index and Mammographic Density during a Premenopausal Weight Loss Intervention Study
From MDPI via Jisc Publications RouterHistory: accepted 2021-06-18, pub-electronic 2021-06-29Publication status: PublishedFunder: Cancer Research UK; Grant(s): C569/A16891, IS-BRC-1215-20007We evaluated the association between short-term change in body mass index (BMI) and breast density during a 1 year weight-loss intervention (Manchester, UK). We included 65 premenopausal women (35–45 years, ≥7 kg adult weight gain, family history of breast cancer). BMI and breast density (semi-automated area-based, automated volume-based) were measured at baseline, 1 year, and 2 years after study entry (1 year post intervention). Cross-sectional (between-women) and short-term change (within-women) associations between BMI and breast density were measured using repeated-measures correlation coefficients and multivariable linear mixed models. BMI was positively correlated with dense volume between-women (r = 0.41, 95%CI: 0.17, 0.61), but less so within-women (r = 0.08, 95%CI: −0.16, 0.28). There was little association with dense area (between-women r = −0.12, 95%CI: −0.38, 0.16; within-women r = 0.01, 95%CI: −0.24, 0.25). BMI and breast fat were positively correlated (volume: between r = 0.77, 95%CI: 0.69, 0.84, within r = 0.58, 95%CI: 0.36, 0.75; area: between r = 0.74, 95%CI: 0.63, 0.82, within r = 0.45, 95%CI: 0.23, 0.63). Multivariable models reported similar associations. Exploratory analysis suggested associations between BMI gain from 20 years and density measures (standard deviation change per +5 kg/m2 BMI: dense area: +0.61 (95%CI: 0.12, 1.09); fat volume: −0.31 (95%CI: −0.62, 0.00)). Short-term BMI change is likely to be positively associated with breast fat, but we found little association with dense tissue, although power was limited by small sample size
A Mismatch in the Ultraviolet Spectra between Low-Redshift and Intermediate-Redshift Type Ia Supernovae as a Possible Systematic Uncertainty for Supernova Cosmology
We present Keck high-quality rest-frame ultraviolet (UV) through optical
spectra of 21 Type Ia supernovae (SNe Ia) in the redshift range 0.11 < z < 0.37
and a mean redshift of 0.22 that were discovered during the Sloan Digital Sky
Survey-II (SDSS-II) SN Survey. Using the broad-band photometry of the SDSS
survey, we are able to reconstruct the SN host-galaxy spectral energy
distributions (SEDs), allowing for a correction for the host-galaxy
contamination in the SN Ia spectra. Comparison of composite spectra constructed
from a subsample of 17 high-quality spectra to those created from a
low-redshift sample with otherwise similar properties shows that the Keck/SDSS
SNe Ia have, on average, extremely similar rest-frame optical spectra but show
a UV flux excess. This observation is confirmed by comparing synthesized
broad-band colors of the individual spectra, showing a difference in mean
colors at the 2.4 - 4.4 sigma level for various UV colors. We further see a
slight difference in the UV spectral shape between SNe with low-mass and
high-mass host galaxies. Additionally, we detect a relationship between the
flux ratio at 2770 and 2900 A and peak luminosity that differs from that
observed at low redshift. We find that changing the UV SED of an SN Ia within
the observed dispersion can change the inferred distance moduli by ~0.1 mag.
This effect only occurs when the data probe the rest-frame UV. We suggest that
this discrepancy could be due to differences in the host-galaxy population of
the two SN samples or to small-sample statistics.Comment: 28 pages, 21 figures, accepted by AJ, spectra are available at
http://www.cfa.harvard.edu/~rfoley/data
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