148 research outputs found
Azelia\u27s Walker
A Biomedical Engineering student, KC Balfour, two Mechanical Engineering students, Jayne Benedict and Gabrielle Merkin, and one Industrial Engineering student, Jordan Ramsey, make up the interdisciplinary senior project team of Azelia’s Walker. The goal of Azelia’s Walker is to create a custom walker for an 8-year-old girl in the San Luis Obispo Community, named Azelia, who has decreased motor control. Her current walker does not suit her active and energetic lifestyle, so Azelia’s Walker is challenged to design and manufacture a collapsible all-terrain walker that best suits Azelia’s needs. Throughout the academic year, Azelia’s Walker participated in the brain-storming and iteration process to produce a final design, created a manufacturing plan, and fabricated a prototype. Several key design features of the new walker are its all-terrain ability, height adjustments, portability, and ergonomic features. This report will take you, the reader, through Azelia’s Walker senior project team’s design and fabrication process. This project culminated in a to-scale prototype. Although the final product succeeded in meeting its all-terrain and portability requirements, the walker was deemed unusable for Azelia due to certain safety concerns outlined in the report. The members of Azelia’s Walker have thoroughly enjoyed this design process and have learned a great deal about the engineering research and design (R&D), analysis, fabrication, and testing process
Identification of an age-dependent biomarker signature in children and adolescents with autism spectrum disorders
Background: Autism spectrum disorders (ASDs) are neurodevelopmental conditions with symptoms manifesting before the age of 3, generally persisting throughout life and affecting social development and com
Galaxy and Apollo as a biologist-friendly interface for high-quality cooperative phage genome annotation
In the modern genomic era, scientists without extensive bioinformatic training need to apply
high-power computational analyses to critical tasks like phage genome annotation. At the
Center for Phage Technology (CPT), we developed a suite of phage-oriented tools housed
in open, user-friendly web-based interfaces. A Galaxy platform conducts computationally
intensive analyses and Apollo, a collaborative genome annotation editor, visualizes the
results of these analyses. The collection includes open source applications such as the
BLAST+ suite, InterProScan, and several gene callers, as well as unique tools developed at
the CPT that allow maximum user flexibility. We describe in detail programs for finding
Shine-Dalgarno sequences, resources used for confident identification of lysis genes such
as spanins, and methods used for identifying interrupted genes that contain frameshifts or
introns. At the CPT, genome annotation is separated into two robust segments that are facilitated through the automated execution of many tools chained together in an operatio
Hydrodynamic transport functions from quantum kinetic theory
Starting from the quantum kinetic field theory [E. Calzetta and B. L. Hu,
Phys. Rev. D37, 2878 (1988)] constructed from the closed-time-path (CTP),
two-particle-irreducible (2PI) effective action we show how to compute from
first principles the shear and bulk viscosity functions in the
hydrodynamic-thermodynamic regime. For a real scalar field with self-interaction we need to include 4 loop graphs in the equation of
motion. This work provides a microscopic field-theoretical basis to the
``effective kinetic theory'' proposed by Jeon and Yaffe [S. Jeon and L. G.
Yaffe, Phys. Rev. D53, 5799 (1996)], while our result for the bulk viscosity
reproduces their expression derived from linear response theory and the
imaginary-time formalism of thermal field theory. Though unavoidably involved
in calculations of this sort, we feel that the approach using fundamental
quantum kinetic field theory is conceptually clearer and methodically simpler
than the effective kinetic theory approach, as the success of the latter
requires clever rendition of diagrammatic resummations which is neither
straightforward nor failsafe. Moreover, the method based on the CTP-2PI
effective action illustrated here for a scalar field can be formulated entirely
in terms of functional integral quantization, which makes it an appealing
method for a first-principles calculation of transport functions of a thermal
non-abelian gauge theory, e.g., QCD quark-gluon plasma produced from heavy ion
collisions.Comment: 25 pages revtex, 11 postscript figures. Final version accepted for
publicatio
Non-equilibrium dynamics of a thermal plasma in a gravitational field
We introduce functional methods to study the non-equilibrium dynamics of a
quantum massless scalar field at finite temperature in a gravitational field.
We calculate the Close Time Path (CTP) effective action and, using its formal
equivalence with the influence functional, derive the noise and dissipation
kernels of the quantum open system in terms of quantities in thermodynamical
equilibrium. Using this fact, we formally prove the existence of a
Fluctuation-Dissipation Relation (FDR) at all temperatures between the quantum
fluctuations of the plasma in thermal equilibrium and the energy dissipated by
the external gravitational field. What is new is the identification of a
stochastic source (noise) term arising from the quantum and thermal
fluctuations in the plasma field, and the derivation of a Langevin-type
equation which describes the non-equilibrium dynamics of the gravitational
field influenced by the plasma. The back reaction of the plasma on the
gravitational field is embodied in the FDR. From the CTP effective action the
contribution of the quantum scalar field to the thermal graviton polarization
tensor can also be derived and it is shown to agree with other techniques, most
notably, Linear Response Theory (LRT). We show the connection between the LRT,
which is applicable for near-equilibrium conditions and the functional methods
used in this work which are useful for fully non-equilibrium conditions.Comment: Final version published in Phys. Rev.
O(N) Quantum fields in curved spacetime
For the O(N) field theory with lambda Phi^4 self-coupling, we construct the
two-particle-irreducible (2PI), closed-time-path (CTP) effective action in a
general curved spacetime. From this we derive a set of coupled equations for
the mean field and the variance. They are useful for studying the
nonperturbative, nonequilibrium dynamics of a quantum field when full back
reactions of the quantum field on the curved spacetime, as well as the
fluctuations on the mean field, are required. Applications to phase transitions
in the early Universe such as the Planck scale or in the reheating phase of
chaotic inflation are under investigation.Comment: 31 pages, 2 figures, uses RevTeX 3.1, LaTeX 2e, AMSfonts 2.2,
graphics 0.6; To appear in Phys. Rev. D (7/15/97
Serum proteomic analysis identifies sex-specific differences in lipid metabolism and inflammation profiles in adults diagnosed with Asperger syndrome
Background: The higher prevalence of Asperger Syndrome (AS) and other autism spectrum conditions in males has been known for many years. However, recent multiplex immunoassay profiling studies have shown that males and females with AS have distinct proteomic changes in serum. Methods. Here, we analysed sera from adults diagnosed with AS (males = 14, females = 16) and controls (males = 13, females = 16) not on medication at the time of sample collection, using a combination of multiplex immunoassay and shotgun label-free liquid chromatography mass spectrometry (LC-MS§ssup§E§esup§). The main objective was to identify sex-specific serum protein changes associated with AS. Results: Multiplex immunoassay profiling led to identification of 16 proteins that were significantly altered in AS individuals in a sex-specific manner. Three of these proteins were altered in females (ADIPO, IgA, APOA1), seven were changed in males (BMP6, CTGF, ICAM1, IL-12p70, IL-16, TF, TNF-alpha) and six were changed in both sexes but in opposite directions (CHGA, EPO, IL-3, TENA, PAP, SHBG). Shotgun LC-MS§ssup§E§esup§ profiling led to identification of 13 serum proteins which had significant sex-specific changes in the AS group and, of these, 12 were altered in females (APOC2, APOE, ARMC3, CLC4K, FETUB, GLCE, MRRP1, PTPA, RN149, TLE1, TRIPB, ZC3HE) and one protein was altered in males (RGPD4). The free androgen index in females with AS showed an increased ratio of 1.63 compared to controls. Conclusion: Taken together, the serum multiplex immunoassay and shotgun LC- MS§ssup§E§esup§ profiling results indicate that adult females with AS had alterations in proteins involved mostly in lipid transport and metabolism pathways, while adult males with AS showed changes predominantly in inflammation signalling. These results provide further evidence that the search for biomarkers or novel drug targets in AS may require stratification into male and female subgroups, and could lead to the development of novel targeted treatment approaches
Spinodal Decomposition and Inflation: Dynamics and Metric Perturbations
We analyse the dynamics of spinodal decomposition in inflationary cosmology
using the closed time path formalism of out of equilibrium quantum field theory
combined with the non-perturbative Hartree approximation. In addition to a
general analysis, we compute the detailed evolution of two inflationary models
of particular importance: lambda Phi^4 new inflation and natural inflation. We
compute the metric fluctuations resulting from inflationary phase transitions
in the slow roll approximation, showing that there exists a regime for which
quantum fluctuations of the inflaton field result in a significant deviation in
the predictions of the spectrum of primordial density perturbations from
standard results. We provide case examples for which a blue tilt to the power
spectrum (i.e. n_s > 1) results from the evolution of a single inflaton field,
and demonstrate that field fluctuations may result in a scalar amplitude of
fluctuations significantly below standard predictions, resulting in a slight
alleviation of the inflationary fine tuning problem. We show explicitly that
the metric perturbation spectrum resulting from inflation depends upon the
state at the outset of the inflationary phase.Comment: 26 pages, 19 figure
Stochastic Gravity: A Primer with Applications
Stochastic semiclassical gravity of the 90's is a theory naturally evolved
from semiclassical gravity of the 70's and 80's. It improves on the
semiclassical Einstein equation with source given by the expectation value of
the stress-energy tensor of quantum matter fields in curved spacetimes by
incorporating an additional source due to their fluctuations. In stochastic
semiclassical gravity the main object of interest is the noise kernel, the
vacuum expectation value of the (operator-valued) stress-energy bi-tensor, and
the centerpiece is the (stochastic) Einstein-Langevin equation. We describe
this new theory via two approaches: the axiomatic and the functional. The
axiomatic approach is useful to see the structure of the theory from the
framework of semiclassical gravity. The functional approach uses the
Feynman-Vernon influence functional and the Schwinger-Keldysh close-time-path
effective action methods which are convenient for computations. It also brings
out the open systems concepts and the statistical and stochastic contents of
the theory such as dissipation, fluctuations, noise and decoherence. We then
describe the application of stochastic gravity to the backreaction problems in
cosmology and black hole physics. Intended as a first introduction to this
subject, this article places more emphasis on pedagogy than completeness.Comment: 46 pages Latex. Intended as a review in {\it Classical and Quantum
Gravity
Stochastic Gravity: Theory and Applications
Whereas semiclassical gravity is based on the semiclassical Einstein equation
with sources given by the expectation value of the stress-energy tensor of
quantum fields, stochastic semiclassical gravity is based on the
Einstein-Langevin equation, which has in addition sources due to the noise
kernel.In the first part, we describe the fundamentals of this new theory via
two approaches: the axiomatic and the functional. In the second part, we
describe three applications of stochastic gravity theory. First, we consider
metric perturbations in a Minkowski spacetime: we compute the two-point
correlation functions for the linearized Einstein tensor and for the metric
perturbations. Second, we discuss structure formation from the stochastic
gravity viewpoint. Third, we discuss the backreaction of Hawking radiation in
the gravitational background of a quasi-static black hole.Comment: 75 pages, no figures, submitted to Living Reviews in Relativit
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