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Florida Institute of Technology

Series

2003

Articles 1 - 23 of 23

Full-Text Articles in Physical Sciences and Mathematics

Physics First, Marcelo Alonso Dec 2003

Physics First, Marcelo Alonso

Aerospace, Physics, and Space Science Faculty Publications

It is true that now most biology courses begin with the DNA molecule, and many chemistry courses introduce the notion of electronic orbitals in atoms and molecules, topics for which students are not well prepared, since most of them have not taken physics courses. Physics courses in turn relegate to the end some discussion of the structure of matter and electromagnetic interaction, or do not discuss that at all. Thus, students miss the overall picture.

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Perpendicular Transport Of Solar Energetic Particles In Heliospheric Magnetic Fields, Ming Zhang, Jack Randy Jokipii, Robert Bruce Mckibben Sep 2003

Perpendicular Transport Of Solar Energetic Particles In Heliospheric Magnetic Fields, Ming Zhang, Jack Randy Jokipii, Robert Bruce Mckibben

Aerospace, Physics, and Space Science Faculty Publications

This paper presents direct observational evidence for large perpendicular diffusive flows of solar energetic particles in heliospheric magnetic fields. Using anisotropy measurements of 40-92 MeV protons obtained by the High-Energy Telescope of the COSPIN consortium on Ulysses at high heliographic latitudes, we find that during several gradual solar particle events, for periods of many hours, the observed particle flow is directed at significant angles to the measured local magnetic field direction, which can only be explained by cross-field diffusion. The variation of the particle flow direction with the magnetic field direction seen in the 2000 July 14 solar energetic particle …

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Constraining The Evolution Of Zz Ceti, Anjum S. Mukadam, Matt A. Wood, Nicole M. Silvestri Sep 2003

Constraining The Evolution Of Zz Ceti, Anjum S. Mukadam, Matt A. Wood, Nicole M. Silvestri

Aerospace, Physics, and Space Science Faculty Publications

We report our analysis of the stability of pulsation periods in the DAV star (pulsating hydrogen atmosphere white dwarf) ZZ Ceti, also called R548. On the basis of observations that span 31 years, we conclude that the period 213. 13 s observed in ZZ Ceti drifts at a rate dP/dt ≤ (5.5 ± 1.9) × 10ˉ¹⁵ s sˉ¹, after correcting for proper motion. Our results are consistent with previous Ṗ values for this mode and an improvement over them because of the larger time base. The characteristic stability timescale implied for the pulsation period is | Ṗ / |≥ 1.2 …

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Elemental Fractionation In Small Solar Energetic Particle Events, Penny L. Slocum, Joseph R. Dwyer Sep 2003

Elemental Fractionation In Small Solar Energetic Particle Events, Penny L. Slocum, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

Using the Solar Isotope Spectrometer on the Advanced Composition Explorer (ACE), we have measured the 11.0-21.8 MeV nucleon-1 heavy (Z ≥ 6) element abundances of 39 small solar energetic particle (SEP) events that occurred between 1998 April 3 and 2002 February 26. Using He isotope data from the UltraLow-Energy Isotope Spectrometer on ACE, we have classified the events according to their 0.5-2.0 MeV nucleonˉ¹ ³He/⁴He ratios. We find that their average heavy-element composition is similar to that of either large gradual events or ³He-rich events, depending on their ³He/⁴He ratio. As seen in recent studies of small SEP events, we …

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The Kolmogorov Equation With Time-Measurable Coefficients, Jay Kovats Jul 2003

The Kolmogorov Equation With Time-Measurable Coefficients, Jay Kovats

Mathematics and System Engineering Faculty Publications

Using both probabilistic and classical analytic techniques, we investigate the parabolic Kolmogorov equation $$ L_t v +\frac {\partial v}{\partial t}\equiv \frac 12 a^{ij}(t)v_{x^ix^j} +b^i(t) v_{x^i} -c(t) v+ f(t) +\frac {\partial v}{\partial t}=0 $$ in $H_T:=(0,T) \times E_d$ and its solutions when the coefficients are bounded Borel measurable functions of $t$. We show that the probabilistic solution $v(t,x)$ defined in $\bar H_T$, is twice differentiable with respect to $x$, continuously in $(t,x)$, once differentiable with respect to $t$, a.e. $t \in [0,T)$ and satisfies the Kolmogorov equation $L_t v +\frac {\partial v}{\partial t}=0$ a.e. in $\bar H_T$. Our main tool will …

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Pks 0736+017: A Striking Optical Flare And Intriguing Microvariability, Sandra D. Clements, A Jenks, Y Torres Jul 2003

Pks 0736+017: A Striking Optical Flare And Intriguing Microvariability, Sandra D. Clements, A Jenks, Y Torres

Aerospace, Physics, and Space Science Faculty Publications

The compact, flat-spectrum radio quasar PKS 0736+017 was monitored for microvariability on 10 nights in early 2002 using the 0.9 m SARA telescope on Kitt Peak in Arizona. On January 14, PKS 0736+017 flared dramatically, brightening by 1.3 R mag in 2 hours. Prior to the flare, PKS 0736+017 exhibited quasi-periodic variations. During and after the flare, more complex oscillations occurred. Impressive variability was displayed on two additional nights in January, while observations during the following 3 months found PKS 0736+017 to be fairly quiescent. PKS 0736+017 was somewhat redder while brighter and fading than when dimmer but flaring. During …

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Nonlinear Collisionless Perpendicular Diffusion Of Charged Particles, William H. Matthaeus, Gang Qin, John William Bieber, Gary Paul Zank Jun 2003

Nonlinear Collisionless Perpendicular Diffusion Of Charged Particles, William H. Matthaeus, Gang Qin, John William Bieber, Gary Paul Zank

Aerospace, Physics, and Space Science Faculty Publications

A nonlinear theory of the perpendicular diffusion of charged particles is presented, including the influence of parallel scattering and dynamical turbulence. The theory shows encouraging agreement with numerical simulations.

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Evidence For A Suprathermal Seed Population Of Heavy Ions Accelerated By Interplanetary Shocks Near 1 Au, Mihir I. Desai, Glenn M. Mason, Joseph R. Dwyer, Joseph E. Mazur, Robert E. Gold, Stamatios M. Krimigis, Charles W. Smith, Ruth M. Skoug May 2003

Evidence For A Suprathermal Seed Population Of Heavy Ions Accelerated By Interplanetary Shocks Near 1 Au, Mihir I. Desai, Glenn M. Mason, Joseph R. Dwyer, Joseph E. Mazur, Robert E. Gold, Stamatios M. Krimigis, Charles W. Smith, Ruth M. Skoug

Aerospace, Physics, and Space Science Faculty Publications

We have surveyed the 0.1-10 MeV nucleonˉ¹ elemental abundances at 72 interplanetary (IP) shocks observed by the Ultra-Low-Energy Isotope Spectrometer on board the Advanced Composition Explorer from 1997 October through 2002 September. We find the following: (1) The C/O ratios in IP shocks were substantially depleted (by more than ∼40%) relative to solar wind values. (2) The IP shock abundances were poorly correlated with those measured in the slow and fast solar wind. (3) Energetic ions above ∼0.1 MeV nucleonˉ¹ from impulsive and gradual solar energetic particle events (SEPs) were present upstream of all the IP shocks in our survey. …

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Hyperspectral Remote Sensing Protocol Development For Submerged Aquatic Vegetation In Shallow Waters, Charles R. Bostater Jr., T. Ghir, L. Bassetti, Carlton Hall, E. Reyier, R. Lowers, K. Holloway-Adkins, Robert Virnstein Feb 2003

Hyperspectral Remote Sensing Protocol Development For Submerged Aquatic Vegetation In Shallow Waters, Charles R. Bostater Jr., T. Ghir, L. Bassetti, Carlton Hall, E. Reyier, R. Lowers, K. Holloway-Adkins, Robert Virnstein

Ocean Engineering and Marine Sciences Faculty Publications

Submerged aquatic vegetation (SAV) is an important indicator of freshwater and marine water quality in almost all shallow water aquatic environments. Throughout the world the diversity of submerged aquatic vegetation appears to be in decline, although sufficient historical data, of sufficient quantitative quality is lacking. Hyperspectral remote sensing technology, available from low altitude aircraft sensors, may provide a basis to improve upon existing photographic regional assessments and monitoring concerned with the aerial extent and coverage of SAV. In addition, modern low altitude remote sensing may also help in the development of environmental satellite requirements for future satellite payloads. This paper …

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Two-Point Boundary Value Problems For Higher-Order Linear Differential Equations With Strong Singularities, Ravi P. Agarwal, Ivan T. Kiguradze Jan 2003

Two-Point Boundary Value Problems For Higher-Order Linear Differential Equations With Strong Singularities, Ravi P. Agarwal, Ivan T. Kiguradze

Mathematics and System Engineering Faculty Publications

For strongly singular higher-order linear differential equations together with two-point conjugate and right-focal boundary conditions, we provide easily verifiable best possible conditions which guarantee the existence of a unique solution. Copyright © 2006 Hindawi Publishing Corporation. All rights reserved.

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Birkhoff-Kellogg Theorems On Invariant Directions For Multimaps, Ravi P. Agarwal, Donal O'Regan Jan 2003

Birkhoff-Kellogg Theorems On Invariant Directions For Multimaps, Ravi P. Agarwal, Donal O'Regan

Mathematics and System Engineering Faculty Publications

We establish Birkhoff-Kellogg type theorems on invariant directions for a general class of maps. Our results, in particular, apply to Kakutani, acyclic, O'Neill, approximable, admissible, and script U signCK maps.

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Random Fixed Point Theory In Spaces With Two Metrics, Donal O'Regan, Naseer Shahzad, Ravi P. Agarwal Jan 2003

Random Fixed Point Theory In Spaces With Two Metrics, Donal O'Regan, Naseer Shahzad, Ravi P. Agarwal

Mathematics and System Engineering Faculty Publications

We present new random fixed point theorems in spaces with two metrics. Our results extend recent results of Tan and Yuan [10] and Xu [11].

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Common Fixed Point Theorems For A Pair Of Countably Condensing Mappings In Ordered Banach Spaces, Bapurao C. Dhage, Donal O'Regan, Ravi P. Agarwal Jan 2003

Common Fixed Point Theorems For A Pair Of Countably Condensing Mappings In Ordered Banach Spaces, Bapurao C. Dhage, Donal O'Regan, Ravi P. Agarwal

Mathematics and System Engineering Faculty Publications

In this paper some common fixed point theorems for a pair of multivalued weakly isotone mappings on an ordered Banach space are proved.

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A Non-Markovian Queueing System With A Variable Number Of Channels, Hong-Tam T. Rosson, Jewgeni H. Dshalalow Jan 2003

A Non-Markovian Queueing System With A Variable Number Of Channels, Hong-Tam T. Rosson, Jewgeni H. Dshalalow

Mathematics and System Engineering Faculty Publications

In this paper we study a queueing model of type GI/M/m̃a/∞ with m parallel channels, sonic of which may suspend their service at specified random moments of time. Whether or not this phenomenon occurs depends on the queue length. The queueing process, which we target, turns out to be semi-regenerative, and we fully explore this utilizing semi-regenerative techniques. This is contrary to the more traditional supplementary variable approach and the less popular approach of combination semi-regenerative and supplementary variable technique. We pass to the limiting distribution of the continuous time parameter process through the embedded Markov chain for which we …

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Absorption Spectroscopy Of Colored Dissolved Organic Carbon In Georgia (Usa) Rivers: The Impact Of Molecular Size Distribution, Yosef Z. Yacobi, James J. Alberts, Monika Takacs, Michelle Mcelvaine Jan 2003

Absorption Spectroscopy Of Colored Dissolved Organic Carbon In Georgia (Usa) Rivers: The Impact Of Molecular Size Distribution, Yosef Z. Yacobi, James J. Alberts, Monika Takacs, Michelle Mcelvaine

Ocean Engineering and Marine Sciences Faculty Publications

Dissolved organic carbon (DOC) was collected in six rivers that transect the coastal plain of Georgia in July 1999 and February 2000. DOC concentrations ranged from 4.9 to 40.7 g m-3 and from 7.1 to 40.5 g m-3, respectively. The absorption coefficient at 440 nm was highly correlated with DOC concentration, suggesting that the optical parameter may be utilized for rapid estimation of DOC in these waters. The isolated DOC was separated into fractions of operationally defined molecular size, using an ultrafiltration technique that yielded three fractions: <10 ("small"), 10-50 ("medium") and >50 ("large") kilodalton. The smallest fraction was the most abundant (>50%) in …

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Multiple Positive Solutions For A Class Of Quasilinear Elliptic Boundary-Value Problems, Kanishka Perera Jan 2003

Multiple Positive Solutions For A Class Of Quasilinear Elliptic Boundary-Value Problems, Kanishka Perera

Mathematics and System Engineering Faculty Publications

Using variational arguments we prove some nonexistence and multiplicity results for positive solutions of a class of elliptic boundary-value problems involving the p-Laplacian and a parameter.

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Existence Theory For Single And Multiple Solutions To Semipositone Discrete Dirichlet Boundary Value Problems With Singular Dependent Nonlinearities, Daqing Jiang, Lili Zhang, Donal O'Regan, Ravi P. Agarwal Jan 2003

Existence Theory For Single And Multiple Solutions To Semipositone Discrete Dirichlet Boundary Value Problems With Singular Dependent Nonlinearities, Daqing Jiang, Lili Zhang, Donal O'Regan, Ravi P. Agarwal

Mathematics and System Engineering Faculty Publications

In this paper we establish the existence of single and multiple solutions to the semipositone discrete Dirichlet boundary value problem {Δ²y(i - 1) + μf(i, y(i)) = 0, i ∈ {1, 2, ..., T} y(0) = y(T + 1) = 0, where μ > 0 is a constant and our nonlinear term f(i, u) may be singular at u = 0.

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Heterogeneous Photocatalytic Reduction Of Ferrate(Vi) In Uv-Irradiated Titania Suspensions: Role In Enhancing Destruction Of Nitrogen-Containing Pollutants, Virender K. Sharma, Kurt Winkelmann, Yekaterina Krasnova, Changyoul Lee, Mary Sohn Jan 2003

Heterogeneous Photocatalytic Reduction Of Ferrate(Vi) In Uv-Irradiated Titania Suspensions: Role In Enhancing Destruction Of Nitrogen-Containing Pollutants, Virender K. Sharma, Kurt Winkelmann, Yekaterina Krasnova, Changyoul Lee, Mary Sohn

Chemistry and Chemical Engineering Faculty Publications

The results of the heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated TiO2 suspensions are presented and suggest indirect observation of the formation of Fe(V) by the photoreduction of Fe(VI) with ecb- at TiO2 surfaces. Because Fe(V) selectively and rapidly oxidizes low reactivity pollutants with the production of the non-toxic by-product, Fe(III), the photocatalytic reduction of Fe(VI) has a role in pollution remediation processes. The experiments were conducted as a function of TiO2 suspension concentrations, Fe(VI) concentrations, and pH in basic media. The initial rate of Fe(VI) reduction gave a fractional order with respect to initial Fe(VI) concentrations and adheres to …

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Delay In Solar Energetic Particle Onsets At High Heliographic Latitudes, Silvia C. Dalla, Ming Zhang Jan 2003

Delay In Solar Energetic Particle Onsets At High Heliographic Latitudes, Silvia C. Dalla, Ming Zhang

Aerospace, Physics, and Space Science Faculty Publications

Ulysses observations have shown that solar energetic particles (SEPs) can easily reach high heliographic latitudes. To obtain information on the release and propagation of SEPs prior to their arrival at Ulysses, we analyse the onsets of nine large high-latitude particle events. We measure the onset times in several energy channels, and plot them versus inverse particle speed. This allows us to derive an experimental path length and time of release from the solar atmosphere. We repeat the procedure for near-Earth observations by Wind and SOHO. We find that the derived path lengths at Ulysses are 1.06 to 2.45 times the …

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2mass J0516288+260738: Discovery Of The First Eclipsing Late K + Brown Dwarf Binary System?, Sonja L. Schüh, Matt A. Wood Jan 2003

2mass J0516288+260738: Discovery Of The First Eclipsing Late K + Brown Dwarf Binary System?, Sonja L. Schüh, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

We report the discovery of a new eclipsing system less than one arcminute south of the pulsating DB white dwarf KUV 05134+2605 . The object could be identified with the point source 2MASS J0516288+260738 published by the Two Micron All Sky Survey. We present and discuss the first light curves as well as some additional colour and spectral information. The eclipse period of the system is 1.29 d, and, assuming this to be identical to the orbital period, the best light curve solution yields a mass ratio of m₂/m₁=0.11, a radius ratio of r₂/r₁ ≈ 1 and an inclination of …

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Multisite Observations Of The Pms Δ Scuti Star V351 Ori, Vincenzo Ripepi, T D. Oswalt, Mark J. Rudkin, Kyle B. Johnston Jan 2003

Multisite Observations Of The Pms Δ Scuti Star V351 Ori, Vincenzo Ripepi, T D. Oswalt, Mark J. Rudkin, Kyle B. Johnston

Aerospace, Physics, and Space Science Faculty Publications

We present the results of multisite observations spanning two years on the pre-main-sequence (PMS) star V351 Ori. A total of around 180 hours of observations over 29 nights have been collected, allowing us to measure five different periodicities, most likely related to the δ Scuti variability of V351 Ori. Comparison with the predictions of linear nonadiabatic radial pulsation models put stringent constraints on the stellar parameters and indicate that the distance to V351 Ori is intermediate between the lower limit measured by Hipparcos (210 pc) and that of the Orion Nebula (450 pc). However, radial pulsation models are unable to …

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The Everchanging Pulsating White Dwarf Gd358, Souza Oliveira Kepler, Matt A. Wood, Nicole M. Silvestri, Thomas J. Ahrens Jan 2003

The Everchanging Pulsating White Dwarf Gd358, Souza Oliveira Kepler, Matt A. Wood, Nicole M. Silvestri, Thomas J. Ahrens

Aerospace, Physics, and Space Science Faculty Publications

We report 323 hours of nearly uninterrupted time series photometric observations of the DBV star GD 358 acquired with the Whole Earth Telescope (WET) during May 23rd to June 8th, 2000. We acquired more than 232 000 independent measurements. We also report on 48 hours of time-series photometric observations in Aug 1996. We detected the non-radial g-modes consistent with degree ℓ = 1 and radial order 8 to 20 and their linear combinations up to 6th order. We also detect, for the first time, a high amplitude ℓ = 2 mode, with a period of 796 s. In the 2000 …

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Ulysses Cospin Observations Of Cosmic Rays And Solar Energetic Particles From The South Pole To The North Pole Of The Sun During Solar Maximum, Robert Bruce Mckibben, Ming Zhang Jan 2003

Ulysses Cospin Observations Of Cosmic Rays And Solar Energetic Particles From The South Pole To The North Pole Of The Sun During Solar Maximum, Robert Bruce Mckibben, Ming Zhang

Aerospace, Physics, and Space Science Faculty Publications

In 2000–2001 Ulysses passed from the south to the north polar regions of the Sun in the inner heliosphere, providing a snapshot of the latitudinal structure of cosmic ray modulation and solar energetic particle populations during a period near solar maximum. Observations from the COSPIN suite of energetic charged particle telescopes show that latitude variations in the cosmic ray intensity in the inner heliosphere are nearly non-existent near solar maximum, whereas small but clear latitude gradients were observed during the similar phase of Ulysses’ orbit near the 1994–95 solar minimum. At proton energies above ∼10 MeV and extending up to …

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