588 research outputs found
Improving patient access in oncology clinics using simulation
Purpose: Providing timely access is an important measure of patient satisfaction in specialty care clinicssuch as cancer centers. Excessive patient wait time to see an oncologist is very critical for cancer patients asthey often benefit from starting the treatment process as soon as possible. This paper addresses capacityplanning for both new and returning patients in cancer clinics. This research is motivated by a cancercenter in Texas that seeks to improve its clinical performance to decrease new patient wait time to see anoncologist.Design/methodology/approach: A simulation model is proposed to assess new patient access tooncologists when employing several tactical and operational policies such as resource flexibility,specialization flexibility, and reserving slots for new patients. The model utilizes two years of data collectedfrom a cancer center in Texas.Findings:The results suggest the best combination of operating policies in order to allocate patientdemand to providers. This study also determines the required capacity level to provide timely access fornew patients.Originality/value: Although the literature in outpatient scheduling and capacity planning is rich, newpatient access in oncology clinics has received limited attention. The few existing studies do not considerpatient no-shows and cancellations, and to the best of our knowledge, no study addresses individualoncologist clinic flexibility and the idea of reserving slots for new patientsPeer Reviewe
A Random Keys Genetic Algorithm for Job Shop Scheduling
https://deepblue.lib.umich.edu/bitstream/2027.42/154143/1/39015099114574.pd
The Lyman Alpha Forest in Hierarchical Cosmologies
The comparison of quasar absorption spectra with numerically simulated
spectra from hierarchical cosmological models of structure formation promises
to be a valuable tool to discriminate among these models. We present simulation
results for the column density, Doppler b parameter, and optical depth
probability distributions for five popular cosmological models.Comment: 4 pages, 3 figures, uses aipproc.sty, to appear in the Proceedings of
the 9th Annual October Astrophysics Conference in Maryland, "After the Dark
Ages: When Galaxies Were Young (the Universe at 2<z<5)", ed. S. S. Holt and
E. P. Smith, October 12-14, 199
On the Detectability of Turbulence and Bulk Flows in X-ray Clusters
Cooling flows, cluster mergers and motions of galaxies through the cluster
gas with supersonic and sonic velocities must lead to large scale motions of
the intracluster medium (ICM). A high-resolution numerical simulation of X-ray
cluster formation by Norman and Bryan predicts cluster-wide turbulence with
v_turb ~ 300-600 ~km/s and eddy scales l_outer ~ 100-500 kpc, the larger
numbers being characteristic of turbulence near the virial radius, while the
smaller numbers pertain to the core. The simulation also predicts the existence
of ordered bulk flows in the core with v ~ 400 km/s on scales of several
hundred kpc. In this paper we consider the observability of such fluid motions
via the distortions it induces in the CMB via the kinematic SZ effect, as well
as via Doppler broadening and shifting of metal lines in the X-ray spectrum. We
estimate |\Delta T/T|_kinematic < few X 10^{-6} -- at or below current limits
of detectability. However, we find that an energy resolution of a few eV is
sufficient to detect several Doppler shifted components in the 6.7 keV Fe line
in the core of the cluster.Comment: 13 pages, 5 figures, Astronomy Letters, accepte
Numerical Simulations of High Redshift Star Formation in Dwarf Galaxies
We present first results from three-dimensional hydrodynamic simulations of
the high redshift formation of dwarf galaxies. The simulations use an Eulerian
adaptive mesh refinement technique to follow the non-equilibrium chemistry of
hydrogen and helium with cosmological initial conditions drawn from a popular
Lambda-dominated CDM model. We include the effects of reionization using a
uniform radiation field, a phenomenological description of the effect of star
formation and, in a separate simulation, the effects of stellar feedback. The
results highlight the effects of stellar feedback and photoionization on the
baryon content and star formation of galaxies with virial temperatures of
approximately 10^4K. Dwarf sized dark matter halos that assemble prior to
reionization are able to form stars. Most halos of similar mass that assemble
after reionization do not form stars by redshift of three. Dwarf galaxies that
form stars show large variations in their gas content because of stellar
feedback and photoionization effects. Baryon-to-dark matter mass ratios are
found to lie below the cosmic mean as a result of stellar feedback. The
supposed substructure problem of CDM is critically assessed on the basis of
these results. The star formation histories modulated by radiative and stellar
feedbacks are discussed. In addition, metallicities of individual objects are
shown to be naturally correlated with their mass-to-light ratios as is also
evident in the properties of local dwarf galaxies.Comment: 27 pages, 8 figures, accepted for publication in Ap
Ocean Color Measurements with the Operational Land Imager on Landsat-8: Implementation and Evaluation in SeaDAS
The Operational Land Imager (OLI) is a multispectral radiometer hosted on the recently launched Landsat8 satellite. OLI includes a suite of relatively narrow spectral bands at 30 m spatial resolution in the visible to shortwave infrared, which makes it a potential tool for ocean color radiometry: measurement of the reflected spectral radiance upwelling from beneath the ocean surface that carries information on the biogeochemical constituents of the upper ocean euphotic zone. To evaluate the potential of OLI to measure ocean color, processing support was implemented in Sea-viewing Wide Field-of-View Sensor (SeaWiFS) Data Analysis System (SeaDAS), which is an open-source software package distributed by NASA for processing, analysis, and display of ocean remote sensing measurements from a variety of spaceborne multispectral radiometers. Here we describe the implementation of OLI processing capabilities within SeaDAS, including support for various methods of atmospheric correction to remove the effects of atmospheric scattering and absorption and retrieve the spectral remote sensing reflectance (Rrs; sr1). The quality of the retrieved Rrs imagery will be assessed, as will the derived water column constituents, such as the concentration of the phytoplankton pigment chlorophyll a
The Role of the PAX8/PPARĪ³ Fusion Oncogene in Thyroid Cancer
Thyroid cancer is uncommon and exhibits relatively low mortality rates. However, a subset of patients experience inexorable growth, metastatic spread, and mortality. Unfortunately, for these patients, there have been few significant advances in treatment during the last 50 years. While substantial advances have been made in recent years about the molecular genetic events underlying papillary thyroid cancer, the more aggressive follicular thyroid cancer remains poorly understood. The recent discovery of the PAX8/PPARĪ³ translocation in follicular thyroid carcinoma has promoted progress in the role of PPARĪ³ as a tumor suppressor and potential therapeutic target. The PAX8/PPARĪ³ fusion gene appears to be an oncogene. It is most often expressed in follicular carcinomas and exerts a dominant-negative effect on wild-type PPARĪ³, and stimulates transcription of PAX8-responsive promoters. PPARĪ³ agonists have shown promising results in vitro, although very few studies have been conducted to assess the clinical impact of these agents
Potential Nighttime Contamination of CERES Clear-sky Field of View by Optically Thin Cirrus during the CRYSTAL-FACE Campaign
We investigate the outgoing broadband longwave (LW, 5 to approx. 200 microns) and window (WIN, 8 to approx. 12 microns) channel radiances at the top of atmosphere (TOA) under clear-sky conditions, using data acquired by the Cloud and the Earth s Radiant Energy System (CERES) and Moderate-Resolution Imaging Spectroradiometer (MODIS) instruments onboard the NASA Terra satellite platform. In this study, detailed analyses are performed on the CERES Single Scanner Footprint TOA/Surface Fluxes and Clouds product to understand the radiative effect of thin cirrus. The data are acquired over the Florida area during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida Area Cirrus Experiment (CRYSTAL-FACE) field program. Of particular interest is the anisotropy associated with the radiation field. Measured CERES broadband radiances are compared to those obtained from rigorous radiative transfer simulations. Analysis of results from this comparison indicates that the simulated radiances tend to be larger than their measured counterparts, with differences ranging from 2.1% to 8.3% for the LW band and from 1.7% to 10.6% for the WIN band. The averaged difference in radiance is approximately 4% for both the LW and WIN channels. A potential cause for the differences could be the presence of thin cirrus (i.e., optically thin ice clouds with visible optical thicknesses smaller than approximately 0.3). The detection and quantitative analysis of these thin cirrus clouds are challenging even with sophisticated multispectral instruments. While large differences in radiance between the CERES observations and the theoretical calculations are found, the corresponding difference in the anisotropic factors is very small (0.2%). Furthermore, sensitivity studies show that the influence due to a 1 K bias of the surface temperature on the errors of the LW and WIN channel radiances is of the same order as that associated with a 2% bias of the surface emissivity. The LW and WIN errors associated with a 5% bias of water vapor amount in the lower atmosphere in conjunction with a 50% bias of water vapor amount in the upper atmosphere is similar to that of a 1 K bias of the vertical temperature profile. Even with the uncertainties considered for these various factors, the simulated LW and WIN radiances are still larger than the observed radiances if thin cirrus clouds are excluded
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