2,778 research outputs found
Invariant classification of orthogonally separable Hamiltonian systems in Euclidean space
The problem of the invariant classification of the orthogonal coordinate webs
defined in Euclidean space is solved within the framework of Felix Klein's
Erlangen Program. The results are applied to the problem of integrability of
the Calogero-Moser model
NFPA Fluid Powered Vehicle Challenge 2023
This report includes the design process undergone by Team Shifty in designing a vehicle for the NFPA’s Fluid Powered Vehicle challenge. The report covers the background of the competition, research done by the team, engineering specifications for the design, preliminary and final designs, the manufacturing plan and process, project management details, and several recommendations for future teams participating in the challenge.
The National Fluid Power Association, NFPA, is a trade association with the goal of connecting fluid power companies and advancing fluid power. With the goal of advancement in mind, NFPA hosts an annual Fluid Powered Vehicle Challenge (FPVC). Since before the NFPA took over this challenge, Cal Poly has produced a team to compete.
Team Shifty completed research into past Cal Poly teams as well as other competing university teams to define the engineering specifications for the new vehicle and decide the design directions. The final design includes a new frame to address issues with the last teams frame, a new hydraulic circuit design and selection of new components to improve the circuits performance in the FPVC events and reduce losses, and the addition of gear shifting to the vehicle. With respect to hydraulics, a new manifold was sourced to accommodate the simplified fluid circuit, along with a larger motor to allow the vehicle to operate at higher torque. The prior team’s pneumatic system was completely replaced by a pneumatic front gear shifting system. The electronics implemented was the same system as the previous year, including an STM microcontroller, Nextion touch screen display, and Hydraforce valve operator with only two solenoid valves. Working together, these components allowed the rider to toggle between three unique drive modes, including: direct, regen, and sprint.
To produce a functional vehicle, research and planning was put into manufacturing and assembly processes as detailed in the manufacturing plan. The final product failed to perform as proposed in Team Shifty’s Scope of Work, as the vehicle’s rear chain consistently fell off during operation at the competition. This resulted in the vehicle not placing during a few of the challenges, including the Sprint and Endurance races. The cause of this failure was a function of the frame flexing under dynamic loading due to insufficient torsional stiffness, as well as the rear chain being too small to handle the large output torque of the upsized rear motor
Matrix Models, Monopoles and Modified Moduli
Motivated by the Dijkgraaf-Vafa correspondence, we consider the matrix model
duals of N=1 supersymmetric SU(Nc) gauge theories with Nf flavors. We
demonstrate via the matrix model solutions a relation between vacua of theories
with different numbers of colors and flavors. This relation is due to an N=2
nonrenormalization theorem which is inherited by these N=1 theories.
Specializing to the case Nf=Nc, the simplest theory containing baryons, we
demonstrate that the explicit matrix model predictions for the locations on the
Coulomb branch at which monopoles condense are consistent with the quantum
modified constraints on the moduli in the theory. The matrix model solutions
include the case that baryons obtain vacuum expectation values. In specific
cases we check explicitly that these results are also consistent with the
factorization of corresponding Seiberg-Witten curves. Certain results are
easily understood in terms of M5-brane constructions of these gauge theories.Comment: 27 pages, LaTeX, 2 figure
On Kinks and Bound States in the Gross-Neveu Model
We investigate static space dependent \sigx=\lag\bar\psi\psi\rag saddle
point configurations in the two dimensional Gross-Neveu model in the large N
limit. We solve the saddle point condition for \sigx explicitly by employing
supersymmetric quantum mechanics and using simple properties of the diagonal
resolvent of one dimensional Schr\"odinger operators rather than inverse
scattering techniques. The resulting solutions in the sector of unbroken
supersymmetry are the Callan-Coleman-Gross-Zee kink configurations. We thus
provide a direct and clean construction of these kinks. In the sector of broken
supersymmetry we derive the DHN saddle point configurations. Our method of
finding such non-trivial static configurations may be applied also in other two
dimensional field theories.Comment: Revised version. A new section added with derivation of the DHN
static configurations in the sector of broken supersymmetry. Some references
added as well. 25 pp, latex, e-mail [email protected]
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Long-Term Corticosteroid-Sparing Immunosuppression for Cardiac Sarcoidosis.
Background Long-term corticosteroid therapy is the standard of care for treatment of cardiac sarcoidosis (CS). The efficacy of long-term corticosteroid-sparing immunosuppression in CS is unknown. The goal of this study was to assess the efficacy of methotrexate with or without adalimumab for long-term disease suppression in CS, and to assess recurrence and adverse event rates after immunosuppression discontinuation. Methods and Results Retrospective chart review identified treatment-naive CS patients at a single academic medical center who received corticosteroid-sparing maintenance therapy. Demographics, cardiac uptake of 18-fluorodeoxyglucose, and adverse cardiac events were compared before and during treatment and between those with persistent or interrupted immunosuppression. Twenty-eight CS patients were followed for a mean 4.1 (SD 1.5) years. Twenty-five patients received 4 to 8 weeks of high-dose prednisone (>30 mg/day), followed by taper and maintenance therapy with methotrexate±low-dose prednisone (low-dose prednisone, <10 mg/day). Adalimumab was added in 19 patients with persistently active CS or in those with intolerance to methotrexate. Methotrexate±low-dose prednisone resulted in initial reduction (88%) or elimination (60%) of 18-fluorodeoxyglucose uptake, and patients receiving adalimumab-containing regimens experienced improved (84%) or resolved (63%) 18-fluorodeoxyglucose uptake. Radiologic relapse occurred in 8 of 9 patients after immunosuppression cessation, 4 patients on methotrexate-containing regimens, and in no patients on adalimumab-containing regimens. Conclusions Corticosteroid-sparing regimens containing methotrexate with or without adalimumab is an effective maintenance therapy in patients after an initial response is confirmed. Disease recurrence in patients on and off immunosuppression support need for ongoing radiologic surveillance regardless of immunosuppression regimen
CfAIR2: Near Infrared Light Curves of 94 Type Ia Supernovae
CfAIR2 is a large homogeneously reduced set of near-infrared (NIR) light
curves for Type Ia supernovae (SN Ia) obtained with the 1.3m Peters Automated
InfraRed Imaging TELescope (PAIRITEL). This data set includes 4607 measurements
of 94 SN Ia and 4 additional SN Iax observed from 2005-2011 at the Fred
Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes JHKs
photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia
in the nearby universe, with a median redshift of z~0.021 for the normal SN Ia.
CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More
than half of the light curves begin before the time of maximum and the coverage
typically contains ~13-18 epochs of observation, depending on the filter. We
present extensive tests that verify the fidelity of the CfAIR2 data pipeline,
including comparison to the excellent data of the Carnegie Supernova Project.
CfAIR2 contributes to a firm local anchor for supernova cosmology studies in
the NIR. Because SN Ia are more nearly standard candles in the NIR and are less
vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the
supernova cosmology community develop more precise and accurate extragalactic
distance probes to improve our knowledge of cosmological parameters, including
dark energy and its potential time variation.Comment: 31 pages, 15 figures, 10 tables. Accepted to ApJS. v2 modified to
more closely match journal versio
A Bright Submillimeter Source in the Bullet Cluster (1E0657--56) Field Detected with BLAST
We present the 250, 350, and 500 micron detection of bright submillimeter
emission in the direction of the Bullet Cluster measured by the Balloon-borne
Large Aperture Submillimeter Telescope (BLAST). The 500 micron centroid is
coincident with an AzTEC 1.1 mm point-source detection at a position close to
the peak lensing magnification produced by the cluster. However, the 250 micron
and 350 micron centroids are elongated and shifted toward the south with a
differential shift between bands that cannot be explained by pointing
uncertainties. We therefore conclude that the BLAST detection is likely
contaminated by emission from foreground galaxies associated with the Bullet
Cluster. The submillimeter redshift estimate based on 250-1100 micron
photometry at the position of the AzTEC source is z_phot = 2.9 (+0.6 -0.3),
consistent with the infrared color redshift estimation of the most likely IRAC
counterpart. These flux densities indicate an apparent far-infrared luminosity
of L_FIR = 2E13 Lsun. When the amplification due to the gravitational lensing
of the cluster is removed, the intrinsic far-infrared luminosity of the source
is found to be L_FIR <= 10^12 Lsun, consistent with typical luminous infrared
galaxies.Comment: Accepted for publication in the Astrophysical Journal. Maps are
available at http://blastexperiment.info
Over half of the far-infrared background light comes from galaxies at z >= 1.2
Submillimetre surveys during the past decade have discovered a population of
luminous, high-redshift, dusty starburst galaxies. In the redshift range 1 <= z
<= 4, these massive submillimetre galaxies go through a phase characterized by
optically obscured star formation at rates several hundred times that in the
local Universe. Half of the starlight from this highly energetic process is
absorbed and thermally re-radiated by clouds of dust at temperatures near 30 K
with spectral energy distributions peaking at 100 microns in the rest frame. At
1 <= z <= 4, the peak is redshifted to wavelengths between 200 and 500 microns.
The cumulative effect of these galaxies is to yield extragalactic optical and
far-infrared backgrounds with approximately equal energy densities. Since the
initial detection of the far-infrared background (FIRB), higher-resolution
experiments have sought to decompose this integrated radiation into the
contributions from individual galaxies. Here we report the results of an
extragalactic survey at 250, 350 and 500 microns. Combining our results at 500
microns with those at 24 microns, we determine that all of the FIRB comes from
individual galaxies, with galaxies at z >= 1.2 accounting for 70 per cent of
it. As expected, at the longest wavelengths the signal is dominated by
ultraluminous galaxies at z > 1.Comment: Accepted to Nature. Maps available at http://blastexperiment.info
Evidence for an FU Orionis-like Outburst from a Classical T Tauri Star
We present pre- and post-outburst observations of the new FU Orionis-like
young stellar object PTF 10qpf (also known as LkHa 188-G4 and HBC 722). Prior
to this outburst, LkHa 188-G4 was classified as a classical T Tauri star on the
basis of its optical emission-line spectrum superposed on a K8-type
photosphere, and its photometric variability. The mid-infrared spectral index
of LkHa 188-G4 indicates a Class II-type object. LkHa 188-G4 exhibited a steady
rise by ~1 mag over ~11 months starting in Aug. 2009, before a subsequent more
abrupt rise of > 3 mag on a time scale of ~2 months. Observations taken during
the eruption exhibit the defining characteristics of FU Orionis variables: (i)
an increase in brightness by > 4 mag, (ii) a bright optical/near-infrared
reflection nebula appeared, (iii) optical spectra are consistent with a G
supergiant and dominated by absorption lines, the only exception being Halpha
which is characterized by a P Cygni profile, (iv) near-infrared spectra
resemble those of late K--M giants/supergiants with enhanced absorption seen in
the molecular bands of CO and H_2O, and (v) outflow signatures in H and He are
seen in the form of blueshifted absorption profiles. LkHa 188-G4 is the first
member of the FU Orionis-like class with a well-sampled optical to mid-infrared
spectral energy distribution in the pre-outburst phase. The association of the
PTF 10qpf outburst with the previously identified classical T Tauri star LkHa
188-G4 (HBC 722) provides strong evidence that FU Orionis-like eruptions
represent periods of enhanced disk accretion and outflow, likely triggered by
instabilities in the disk. The early identification of PTF 10qpf as an FU
Orionis-like variable will enable detailed photometric and spectroscopic
observations during its post-outburst evolution for comparison with other known
outbursting objects.Comment: 14 pages, 11 figures, ApJ accepte
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