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Full-Text Articles in Physics
Primordial Black Hole Evaporation And Spontaneous Dimensional Reduction, Jonas R. Mureika
Primordial Black Hole Evaporation And Spontaneous Dimensional Reduction, Jonas R. Mureika
Physics Faculty Works
Several different approaches to quantum gravity suggest the effective dimension of spacetime reduces from four to two near the Planck scale. In light of such evidence, this Letter re-examines the thermodynamics of primordial black holes (PBHs) in specific lower-dimensional gravitational models. Unlike in four dimensions, (1 + 1)-D black holes radiate with power P ∼ M2BH, while it is known no (2+1)-D (BTZ) black holes can exist in a non-anti-de Sitter universe. This has important relevance to the PBH population size and distribution, and consequently on cosmological evolution scenarios. The number of PBHs that have evaporated to …
A Proper Motion Study Of The Haro 6-10 Outflow: Evidence For A Subarcsecond Binary, Bruce Wilking, Kevin Marvel, Mark Claussen, Bradley Gerling, Alwyn Wootten, Erika Gibb
A Proper Motion Study Of The Haro 6-10 Outflow: Evidence For A Subarcsecond Binary, Bruce Wilking, Kevin Marvel, Mark Claussen, Bradley Gerling, Alwyn Wootten, Erika Gibb
Physics Faculty Works
We present single-dish and very long baseline interferometry observations of an outburst of water maser emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus molecular cloud and contains a visible T Tauri star with an infrared companion 1farcs3 north. Using the Very Long Baseline Array, we obtained five observations spanning three months and derived absolute positions for 20 distinct maser spots. Three of the masers can be traced over three or more epochs, enabling us to extract absolute proper motions and tangential velocities. We deduce that the masers represent one side of a bipolar outflow …
The Gas/Dust Ratio Of Circumstellar Disks: Testing Models Of Planetesimal Formation, David Horne, Erika Gibb, Terrence Rettig, Sean Brittain, David Tilley, Dinshaw Balsara
The Gas/Dust Ratio Of Circumstellar Disks: Testing Models Of Planetesimal Formation, David Horne, Erika Gibb, Terrence Rettig, Sean Brittain, David Tilley, Dinshaw Balsara
Physics Faculty Works
We present high-resolution, near-infrared NIRSPEC observations of CO absorption toward six class II T Tauri stars: AA Tau, DG Tau, IQ Tau, RY Tau, CW Tau, and Haro 6-5b. 12CO overtone absorption lines originating from the circumstellar disk of each object were used to calculate line-of-sight gas column densities toward each source. We measured the gas/dust ratio as a function of disk inclination, utilizing measured visual extinctions and inclinations for each star. The majority of our sources show further evidence for a correlation between the gas/dust column density ratio and disk inclination similar to that found by Rettig et al.
Simulating A Guitar With A Conventional Sonometer, Zily Burstein, Christina M. Gower, Gabriele U. Varieschi
Simulating A Guitar With A Conventional Sonometer, Zily Burstein, Christina M. Gower, Gabriele U. Varieschi
Physics Faculty Works
In this paper we present a simple way to convert a conventional sonometer into a simulated fretted instrument, such as a guitar or similar, by adding a fingerboard to the sonometer. In particular, we use this modified apparatus in relation to the problem of the instrument intonation, i.e., how to obtain correctly tuned notes on these string instruments. The experimental procedures presented in this study can become a more structured laboratory activity to be used in general physics courses or acoustics classes.
Noncontact Ultrasound Imaging Applied To Cortical Bone Phantoms, John Bulman, K. S. Ganezer, P. W. Halcrow, Ian Neeson
Noncontact Ultrasound Imaging Applied To Cortical Bone Phantoms, John Bulman, K. S. Ganezer, P. W. Halcrow, Ian Neeson
Physics Faculty Works
Purpose: The purpose of this paper was to take the first steps toward applying noncontact ultrasound (NCU) to the tasks of monitoring osteoporosis and quantitative ultrasound imaging (QUS) of cortical bone. The authors also focused on the advantages of NCU, such as its lack of reliance on a technologist to apply transducers and a layer of acoustical coupling gel, the ability of the transducers to operate autonomously as specified by preprogrammed software, and the likely reduction in statistical and systematic errors associated with the variability in the pressure applied by the clinician to the transmitting transducer that NCU might provide. …
Chemical Composition Of Comet C/2007 N3 (Lulin): Another ''Atypical'' Comet, Erika Gibb, Boncho Bonev, Geronimo Villanueva, Michael Disanti, Michael Mumma, Emily Sudholt, Yana Radeva
Chemical Composition Of Comet C/2007 N3 (Lulin): Another ''Atypical'' Comet, Erika Gibb, Boncho Bonev, Geronimo Villanueva, Michael Disanti, Michael Mumma, Emily Sudholt, Yana Radeva
Physics Faculty Works
We measured the volatile chemical composition of comet C/2007 N3 (Lulin) on three dates from 2009 January 30 to February 1 using NIRSPEC, the high-resolution (λ/Δλ ≈ 25,000), long-slit echelle spectrograph at Keck 2. We sampled nine primary (parent) volatile species (H2O, C2H6, CH3OH, H2CO, CH4, HCN, C2H2, NH3, CO) and two product species (OH* and NH2). We also report upper limits for HDO and CH3D. C/2007 N3 (Lulin) displayed an unusual composition when compared to other comets. Based on comets measured to date, CH4 and C2H6 exhibited "normal" abundances relative to water, CO and HCN were only moderately depleted, …
Could Any Black Holes Be Produced At The Lhc?, Jonas R. Mureika, Piero Nicolini, Euro Spallucci
Could Any Black Holes Be Produced At The Lhc?, Jonas R. Mureika, Piero Nicolini, Euro Spallucci
Physics Faculty Works
We introduce analytical quantum gravity modifications of the production cross section for terascale black holes by employing an effective ultraviolet cut off l. We find the new cross sections approach the usual "black disk" form at high energy, while they differ significantly near the fundamental scale from the standard increase with respect to s. We show that the heretofore discontinuous step function used to represent the cross section threshold can realistically be modeled by two functions representing the incoming and final parton states in a high energy collision. The growth of the cross section with collision energy is …
Conformal Cosmology And The Pioneer Anomaly, Gabriele U. Varieschi
Conformal Cosmology And The Pioneer Anomaly, Gabriele U. Varieschi
Physics Faculty Works
No abstract provided.