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2010

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Articles 5581 - 5610 of 8625

Full-Text Articles in Physical Sciences and Mathematics

Science Drivers And Requirements For An Advanced Technology Large Aperture Space Telescope (Atlast): Implications For Technology Development And Synergies With Other Future Facilities, Marc Postman, Tom Brown, Kenneth Sembach, Mauro Giavalisco, Wesley Traub, Karl Stapelfeldt, Daniela Calzetti, William Oegerle, R. Michael Rich, Phillip Stahl, Jason Tumlinson, Matt Mountain, Rémi Soummer, Tupper Hyde Jan 2010

Science Drivers And Requirements For An Advanced Technology Large Aperture Space Telescope (Atlast): Implications For Technology Development And Synergies With Other Future Facilities, Marc Postman, Tom Brown, Kenneth Sembach, Mauro Giavalisco, Wesley Traub, Karl Stapelfeldt, Daniela Calzetti, William Oegerle, R. Michael Rich, Phillip Stahl, Jason Tumlinson, Matt Mountain, Rémi Soummer, Tupper Hyde

Mauro Giavalisco

The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8-meter to 16-meter UVOIR space observatory for launch in the 2025-2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astronphysics, including "Is there life elsewhere in the Galaxy?" We present a range of science drivers that define the main performance requirements for ATLAST (8 to 16 milliarcsec angular resolution, diffraction limited imaging at 0.5 {\mu}m wavelength, minimum collecting area of 45 square meters, high sensitivity to light wavelengths from 0.1 {\mu}m to 2.4 {\mu}m, high stability in wavefront sensing and control). We …

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Spectroscopic Confirmation Of Z~7 Lbgs: Probing The Earliest Galaxies And The Epoch Of Reionization, L. Pentericci, A. Fontana, E. Vanzella, M. Castellano, A. Grazian, M. Dijkstra, K. Boustia, S. Cristiani, M. Dickinson, E. Giallongo, Mauro Giavalisco, R. Maiolino, A. Moorwood, P. Santini Jan 2010

Spectroscopic Confirmation Of Z~7 Lbgs: Probing The Earliest Galaxies And The Epoch Of Reionization, L. Pentericci, A. Fontana, E. Vanzella, M. Castellano, A. Grazian, M. Dijkstra, K. Boustia, S. Cristiani, M. Dickinson, E. Giallongo, Mauro Giavalisco, R. Maiolino, A. Moorwood, P. Santini

Mauro Giavalisco

We present the final results from our ultra-deep spectroscopic campaign with FORS2 at the ESO/VLT for the confirmation of z~7 "z--band dropout" candidates selected from our VLT/Hawk-I imaging survey over three independent fields. In particular we report on two newly discovered galaxies at redshift ~6.7 in the NTT deep field: both galaxies show a Ly-alpha emission line with rest-frame EWs of the order 15-20 A and luminosities of 2-4 X 10^{42} erg/s. We also present the results of ultra-deep observations of a sample of i-dropout galaxies, from which we set a solid upper limit on the fraction of interlopers. Out …

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The Lack Of Intense Lyman~Alpha In Ultradeep Spectra Of Z=7 Candidates In Goods-S: Imprint Of Reionization?, A. Fontana, E. Vanzella, L. Pentericci, M. Castellano, Mauro Giavalisco, A. Grazian, K. Boutsia, S. Christiani, M. Dickinson, E. Giallongo, M. Maiolino, A. Moorwood, P. Santini Jan 2010

The Lack Of Intense Lyman~Alpha In Ultradeep Spectra Of Z=7 Candidates In Goods-S: Imprint Of Reionization?, A. Fontana, E. Vanzella, L. Pentericci, M. Castellano, Mauro Giavalisco, A. Grazian, K. Boutsia, S. Christiani, M. Dickinson, E. Giallongo, M. Maiolino, A. Moorwood, P. Santini

Mauro Giavalisco

We present ultradeep optical spectroscopy obtained with FORS2 on VLT of seven Lyman-break galaxy (LBG) candidates at z>6.5 selected in the GOODS-S field from Hawk-I/VLT and WFC3/HST imaging. For one galaxy we detect a low significance emission line (S/N< 7), located at 9691.5 +/- 0.5A and with flux 3.4 x 10^(-18)erg/cm^2/s. If identified as Lyman alpha, it places the LBG at redshift z=6.972+/- 0.002, with a rest-frame equivalent width EW}=13A. Using Monte Carlo simulations and conservative EW distribution functions at 210 is ~ 2%, and that of observing only one galaxy out of seven with S/N=5 is ~4%, but these can be as small as ~1E-3, depending on the details of the EW distribution. We conclude that either a significant fraction of the candidates is not at high redshift or that some physical mechanism quenches the Lyman alpha emission emerging from the galaxies at z>6.5, abruptly reversing the trend of the increasing fraction of strong emitters with increasing redshift observed up to z~ 6.5. We discuss the possibility that an increasingly neutral intergalactic medium is responsible for such quenching.

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Spectroscopic Confirmation Of Two Lyman Break Galaxies At Redshift Beyond 7, E. Vanzella, L. Pentericci, A. Fontana, A. Grazian, M. Castellano, K. Boutsia, S. Cristiani, M. Dickinson, S. Gallozzi, E. Giallongo, Mauro Giavalisco, R. Maiolino, A. Moorwood, D. Paris, P. Santini Jan 2010

Spectroscopic Confirmation Of Two Lyman Break Galaxies At Redshift Beyond 7, E. Vanzella, L. Pentericci, A. Fontana, A. Grazian, M. Castellano, K. Boutsia, S. Cristiani, M. Dickinson, S. Gallozzi, E. Giallongo, Mauro Giavalisco, R. Maiolino, A. Moorwood, D. Paris, P. Santini

Mauro Giavalisco

We report the spectroscopic confirmation of two Lyman break galaxies at redshift > 7. The galaxies were observed as part of an ultra-deep spectroscopic campaign with FORS2 at the ESO/VLT for the confirmation of z~7 ``z--band dropout'' candidates selected from our VLT/Hawk-I imaging survey. Both galaxies show a prominent emission line at 9735A and 9858A respectively: the lines have fluxes of ~ 1.6-1.2 x 10^(-17) erg/s/cm2 and exhibit a sharp decline on the blue side and a tail on the red side. The asymmetry is quantitatively comparable to the observed asymmetry in z ~ 6 Ly-alpha lines, where absorption by neutral …

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The Rising Star-Formation Histories Of Distant Galaxies And Implications For Gas Accretion With Time, Casey Papovich, Steven L. Finkelstein, Henry C. Ferguson, Jennifer M. Lotz, Mauro Giavalisco Jan 2010

The Rising Star-Formation Histories Of Distant Galaxies And Implications For Gas Accretion With Time, Casey Papovich, Steven L. Finkelstein, Henry C. Ferguson, Jennifer M. Lotz, Mauro Giavalisco

Mauro Giavalisco

Distant galaxies show correlations between their current star-formation rates (SFRs) and stellar masses, implying that their star-formation histories (SFHs) are highly similar. Moreover, observations show that the UV luminosities and stellar masses grow from z=8 to 3, implying that the SFRs increase with time. We compare the cosmologically averaged evolution in galaxies at 3 < z < 8 at constant comoving number density, n = 2 x 10^-4 Mpc^-3. This allows us to study the evolution of stellar mass and star formation in the galaxy predecessors and descendants in ways not possible using galaxies selected at constant stellar mass or SFR, quantities that evolve strongly in time. We show that the average SFH of these galaxies increase smoothly from z=8 to 3 as SFR ~ t^alpha with alpha = 1.7 +/- 0.2. This conflicts with assumptions that the SFR is either constant or declines exponentially in time. We show that the stellar mass growth in these galaxies is consistent with this derived SFH. This provides evidence that the slope of the high-mass end of the IMF is approximately Salpeter unless the duty cycle of star formation is much less than unity. We argue that these relations follow from gas accretion (either through accretion or delivered by mergers) coupled with galaxy disk growth under the assumption that the SFR depends on the local gas surface density. This predicts that gas fractions decrease from z=8 to 3 on average as f_gas ~ (1+z)^0.9 for galaxies with this number density. The implied galaxy gas accretion rates at z > 4 are as fast and may even exceed the SFR: this is the "gas accretion epoch". At z < 4 the SFR overtakes the implied gas accretion rate, indicating a period where galaxies consume gas faster than it is acquired. At z < 3, galaxies with this number density depart from these relations implying that star formation and gas accretion are slowed at later times.

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Deep 1.1 Mm-Wavelength Imaging Of The Goods-S Field By Aztec/Aste - I. Source Catalogue And Number Counts, K. S. Scott, M. S. Yun, G. W. Wilson, J. E. Austermann, E. Aguilar, I. Aretxaga, H. Ezawa, D. Ferrusca, B. Hatsukade, D. H. Hughes, D. Iono, Mauro Giavalisco, R. Kawabe, K. Kohno, P. D. Masukopf, T. Oshima, T. A. Perera, J. Rand, Y. Tamura, T. Tosaki, M Velazquez, C. C. Williams, M. Zeballos Jan 2010

Deep 1.1 Mm-Wavelength Imaging Of The Goods-S Field By Aztec/Aste - I. Source Catalogue And Number Counts, K. S. Scott, M. S. Yun, G. W. Wilson, J. E. Austermann, E. Aguilar, I. Aretxaga, H. Ezawa, D. Ferrusca, B. Hatsukade, D. H. Hughes, D. Iono, Mauro Giavalisco, R. Kawabe, K. Kohno, P. D. Masukopf, T. Oshima, T. A. Perera, J. Rand, Y. Tamura, T. Tosaki, M Velazquez, C. C. Williams, M. Zeballos

Mauro Giavalisco

[Abridged] We present the first results from a 1.1 mm confusion-limited map of the GOODS-S field taken with AzTEC on the ASTE telescope. We imaged a 270 sq. arcmin field to a 1\sigma depth of 0.48 - 0.73 mJy/beam, making this one of the deepest blank-field surveys at mm-wavelengths ever achieved. Although our GOODS-S map is extremely confused, we demonstrate that our source identification and number counts analyses are robust, and the techniques discussed in this paper are relevant for other deeply confused surveys. We find a total of 41 dusty starburst galaxies with S/N >= 3.5 within this uniformly …

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The Great Observatories Origins Deep Survey: Constraints On The Lyman Continuum Escape Fraction Distribution Of Lyman--Break Galaxies At 3.4, E. Vanzella, Mauro Giavalisco, A. Inoue, M. Nonino, F. Fontanot, S. Cristiani, A. Grazian, M. Dickinson, D. Stern, P. Tozzi, E. Giallongo, H. Ferguson, H. Spinrad, K. Boutsia, A. Fontana, P. Rosati Jan 2010

The Great Observatories Origins Deep Survey: Constraints On The Lyman Continuum Escape Fraction Distribution Of Lyman--Break Galaxies At 3.4, E. Vanzella, Mauro Giavalisco, A. Inoue, M. Nonino, F. Fontanot, S. Cristiani, A. Grazian, M. Dickinson, D. Stern, P. Tozzi, E. Giallongo, H. Ferguson, H. Spinrad, K. Boutsia, A. Fontana, P. Rosati

Mauro Giavalisco

We use ultra-deep ultraviolet VLT/VIMOS intermediate-band and VLT/FORS1 narrow-band imaging in the GOODS Southern field to derive limits on the distribution of the escape fraction (f_esc) of ionizing radiation for L >~ L*(z=3) Lyman Break Galaxies (LBGs) at redshift 3.4--4.5. Only one LBG, at redshift z=3.795, is detected in its Lyman continuum (LyC; S/N~5.5), the highest redshift galaxy currently known with a direct detection. Its ultraviolet morphology is quite compact (R_eff=0.8, kpc physical). Three out of seven AGN are also detected in their LyC, including one at redshift z=3.951 and z850 = 26.1. From stacked data (LBGs) we set an …

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Evaluation Of A Rapid Assessment Protocol To Assess Road-Stream Crossings For Aquatic Organism Passage, Scott D. Jackson, Denis Luken Jan 2010

Evaluation Of A Rapid Assessment Protocol To Assess Road-Stream Crossings For Aquatic Organism Passage, Scott D. Jackson, Denis Luken

Scott D. Jackson

The River and Stream Continuity Partnership has developed assessment protocols for evaluating the barrier effects of road-stream crossings. In addition to these protocols, the University of Massachusetts Amherst created an online database and an algorithm for scoring crossing structures according to the degree of obstruction they pose to aquatic organisms. In 2008, The Nature Conservancy and University of Massachusetts collected data to test the robustness and repeatability of the protocol and compare results with those of other fish passage models. A stratified random sample of 317 road stream crossings in Connecticut, Vermont, New Hampshire and Massachusetts that had previously been …

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My Italian Connections: Otto Vogl In Italy, Otto Vogl, Gerald S. Kirshenbaum Jan 2010

My Italian Connections: Otto Vogl In Italy, Otto Vogl, Gerald S. Kirshenbaum

Otto Vogl

This document describes Otto Vogl's work in Italy. From 1975, Vogl served for 3 years as the Chairman of the Scientific Advisory Committee to the President Italo Trapasso of the Plastic Materials Company of Montedison SA, Milan, Italy. He was assigned to restructure the research activities and to organize the Research Division. He was responsible for the appointment of DiDrusco as the Vice President of Research and Paolo Galli as the Director of Research at the company’s facilities in Ferrara. Within a year of Vogl’s reorganization of the research organization the high yield catalyst for the polymerization of propylene was …

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An Analysis Of Past And Future Changes In The Ice Cover Of Two High-Arctic Lakes Based On Synthetic Aperture Radar (Sar) And Landsat Imagery, Timothy L. Cook, Raymond S. Bradley Jan 2010

An Analysis Of Past And Future Changes In The Ice Cover Of Two High-Arctic Lakes Based On Synthetic Aperture Radar (Sar) And Landsat Imagery, Timothy L. Cook, Raymond S. Bradley

Raymond S Bradley

Space-borne remotely sensed data can provide valuable insight into cryospheric processes in remote high-latitude regions for which direct observations are limited. In this study we use synthetic aperture radar (SAR) and Landsat imagery to evaluate recent changes in the ice cover of Upper and Lower Murray Lakes (81°20′N, 69°30′W) on Ellesmere Island, Nunavut, Canada. These data highlight changes in ice conditions that have occurred over the past decade and provide a means for assessing the likely impacts of rising temperatures on future lake-ice conditions. Under current (1997–2007) climatic conditions the Murray Lakes average several weeks of ice-free conditions in August …

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On K4 Of The Gaussian And Eisenstein Integers, Mathieu Dutour Sikiric, Herbert Gangl, Paul Gunnells, Jonathan Hanke, Achill Schürmann, Dan Yasaki Jan 2010

On K4 Of The Gaussian And Eisenstein Integers, Mathieu Dutour Sikiric, Herbert Gangl, Paul Gunnells, Jonathan Hanke, Achill Schürmann, Dan Yasaki

Paul Gunnells

Abstract. In this paper we investigate the structure of the algebraic K-groups K4(Z[i]) and K4(Z[ρ]), where i := √ −1 and ρ := (1 + √ −3)/2. We exploit the close connection between homology groups of GLn(R) for n 6 5 and those of related classifying spaces, then compute the former using Voronoi’s reduction theory of positive definite quadratic and Hermitian forms to produce a very large finite cell complex on which GLn(R) acts. Our main results are (i) K4(Z[i]) is a finite abelian 3-group, and (ii) K4(Z[ρ]) is trivial.

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Excited States In The Large Density Limit: A Variational Approach, Mp Coles, De Pelinovsky, Pg Kevrekidis Jan 2010

Excited States In The Large Density Limit: A Variational Approach, Mp Coles, De Pelinovsky, Pg Kevrekidis

Panos Kevrekidis

Excited states of Bose–Einstein condensates are considered in the large density limit of the Gross–Pitaevskii equation with repulsive inter-atomic interactions and a harmonic potential. The relative dynamics of dark solitons (density dips on the localized condensate) with respect to the harmonic potential and to each other is approximated using the averaged Lagrangian method. This permits a complete characterization of the equilibrium positions of the dark solitons as a function of the chemical potential. It also yields an analytical handle on the oscillation frequencies of dark solitons around such equilibria. The asymptotic predictions are generalized for an arbitrary number of dark …

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Far From Threshold Buckling Analysis Of Thin Films, B Davidovitch, R Schroll, D. Vella, M. Adda-Bedia, E. Cerda Jan 2010

Far From Threshold Buckling Analysis Of Thin Films, B Davidovitch, R Schroll, D. Vella, M. Adda-Bedia, E. Cerda

Benny Davidovitch

Thin films buckle easily and form wrinkled states in regions of well defined size. The extent of a wrinkled region is typically assumed to reflect the zone of in-plane compressive stresses prior to buckling, but recent experiments on ultrathin sheets have shown that wrinkling patterns are signif- icantly longer and follow different scaling laws than those predicted by standard buckling theory. Here we focus on a simple setup to show the striking differences between near-threshold buckling and the analysis of wrinkle patterns in very thin films, which are typically far from threshold.

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Granular Gases Under Extreme Driving, W. Kang, Jonathan Machta, E. Ben-Namin Jan 2010

Granular Gases Under Extreme Driving, W. Kang, Jonathan Machta, E. Ben-Namin

Jonathan Machta

We study inelastic gases in two dimensions using event-driven molecular-dynamics simulations. Our focus is the nature of the stationary state attained by rare injection of large amounts of energy to balance the dissipation due to collisions. We find that under such extreme driving, with the injection rate much smaller than the collision rate, the velocity distribution has a power-law high-energy tail. The numerically measured exponent characterizing this tail is in excellent agreement with predictions of kinetic theory over a wide range of system parameters. We conclude that driving by rare but powerful energy injection leads to a well-mixed gas and …

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A Prospective Cohort Study Of Modifiable Risk Factors For Gestational Diabetes Among Hispanic Women: Design And Baseline Characteristics, Lisa Chasen-Taber, R. T. Fortner, A. Gollenberg, John Buonaccorsi, N. Dole, G. Markenson Jan 2010

A Prospective Cohort Study Of Modifiable Risk Factors For Gestational Diabetes Among Hispanic Women: Design And Baseline Characteristics, Lisa Chasen-Taber, R. T. Fortner, A. Gollenberg, John Buonaccorsi, N. Dole, G. Markenson

John Buonaccorsi

OBJECTIVES: Women diagnosed with gestational diabetes mellitus (GDM) are at high risk for future diabetes, with rates of GDM consistently higher in Hispanic than non-Hispanic white women. Currently recognized risk factors for GDM are absent in up to half of affected women, and studies addressing modifiable risk factors for GDM in Hispanic women are sparse. METHODS: Proyecto Buena Salud is an ongoing prospective cohort study of Hispanic women in Massachusetts designed to assess physical activity, psychosocial stress, and GDM risk. Bilingual interviewers recruit prenatal care patients early in pregnancy and assess activity, trait anxiety, perceived stress, and depressive symptoms using …

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Population Annealing With Weighted Averages: A Monte Carlo Method For Rough Free-Energy Landscapes, Jonathan Machta Jan 2010

Population Annealing With Weighted Averages: A Monte Carlo Method For Rough Free-Energy Landscapes, Jonathan Machta

Jonathan Machta

The population annealing algorithm introduced by Hukushima and Iba is described. Population annealing combines simulated annealing and Boltzmann weighted differential reproduction within a population of replicas to sample equilibrium states. Population annealing gives direct access to the free energy. It is shown that unbiased measurements of observables can be obtained by weighted averages over many runs with weight factors related to the free-energy estimate from the run. Population annealing is well suited to parallelization and may be a useful alternative to parallel tempering for systems with rough free-energy landscapes such as spin glasses. The method is demonstrated for spin glasses.

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Asymptotic Behavior Of The Finite-Size Magnetization As A Function Of The Speed Of Approach To Criticality, Richard S. Ellis, Jonathan Machta, Peter Tak-Hun Otto Jan 2010

Asymptotic Behavior Of The Finite-Size Magnetization As A Function Of The Speed Of Approach To Criticality, Richard S. Ellis, Jonathan Machta, Peter Tak-Hun Otto

Richard S. Ellis

The main focus of this paper is to determine whether the thermodynamic magnetization is a physically relevant estimator of the finite-size magnetization. This is done by comparing the asymptotic behaviors of these two quantities along parameter sequences converging to either a second-order point or the tricritical point in the mean-field Blume–Capel model. We show that the thermodynamic magnetization and the finite-size magnetization are asymptotic when the parameter α governing the speed at which the sequence approaches criticality is below a certain threshold α0. However, when α exceeds α0, the thermodynamic magnetization converges to 0 much faster than the finite-size magnetization. …

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Statistical Modeling Of Agatston Score In Multi-Ethnic Study Of Atherosclerosis (Mesa), Anna Liu, S. Ma, J. Carr, W. Post, R. Kronmal Jan 2010

Statistical Modeling Of Agatston Score In Multi-Ethnic Study Of Atherosclerosis (Mesa), Anna Liu, S. Ma, J. Carr, W. Post, R. Kronmal

Anna Liu

The MESA (Multi-Ethnic Study of Atherosclerosis) is an ongoing study of the prevalence, risk factors, and progression of subclinical cardiovascular disease in a multi-ethnic cohort. It provides a valuable opportunity to examine the development and progression of CAC (coronary artery calcium), which is an important risk factor for the development of coronary heart disease. In MESA, about half of the CAC scores are zero and the rest are continuously distributed. Such data has been referred to as “zero-inflated data” and may be described using two-part models. Existing two-part model studies have limitations in that they usually consider parametric models only, …

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Invariant Weighted Wiener Measures And Almost Sure Global Well-Posedness For The Periodic Derivative Nls, Andrea Nahmod, Tadahiro Oh, Luc Rey-Bellet, Gigliola Staffilani Jan 2010

Invariant Weighted Wiener Measures And Almost Sure Global Well-Posedness For The Periodic Derivative Nls, Andrea Nahmod, Tadahiro Oh, Luc Rey-Bellet, Gigliola Staffilani

Andrea Nahmod

In this paper we construct an invariant weighted Wiener measure associated to the periodic derivative nonlinear Schr\"odinger equation in one dimension and establish global well-posedness for data living in its support. In particular almost surely for data in a Fourier-Lebesgue space ${\mathcal F}L^{s,r}(\T)$ with $s \ge \frac{1}{2}$, $2 < r < 4$, $(s-1)r <-1$ and scaling like $H^{\frac{1}{2}-\epsilon}(\T),$ for small $\epsilon >0$. We also show the invariance of this measure.

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Changes In Extreme Climate Indices For The Northeastern United States, 1870-2006, Paula J. Brown, Raymond S. Bradley, Frank T. Keimig Jan 2010

Changes In Extreme Climate Indices For The Northeastern United States, 1870-2006, Paula J. Brown, Raymond S. Bradley, Frank T. Keimig

Raymond S Bradley

The northeastern United States is one of the most variable climates in the world, and how climate extremes are changing is critical to populations, industries, and the environment in this region.Along-term (1870–2005) temperature and precipitation dataset was compiled for the northeastern United States to assess how the climate has changed. Adjustments were made to daily temperatures to account for changes in mean, variance, and skewness resulting from inhomogeneities, but precipitation data were not adjusted. Trends in 17 temperature and 10 precipitation indices at 40 stations were evaluated over three time periods—1893–2005, 1893– 1950, and 1951–2005—and over 1870–2005 for a subset …

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Anhang: Auszüge Aus Dem Späteren Leben Von Professor Dr. Otto Vogl, Otto Vogl Jan 2010

Anhang: Auszüge Aus Dem Späteren Leben Von Professor Dr. Otto Vogl, Otto Vogl

Otto Vogl

No abstract provided.

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Towards An Automation Of The Circle Method, Andrew Sills Jan 2010

Towards An Automation Of The Circle Method, Andrew Sills

Andrew V. Sills

The derivation of the Hardy-Ramanujan-Rademacher formula for the number of partitions of n is reviewed. Next, the steps for finding analogous formulas for certain restricted classes of partitions or overpartitions is examined, bearing in mind how these calculations can be automated in a CAS. Finally, a number of new formulas of this type which were conjectured with the aid of Mathematica are presented along with results of a test for their numerical accuracy.

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Greening The Curriculum: Augmenting Engineering And Technology Courses With Sustainability Topics, Kurt A. Rosentrater, Elif Kongar Jan 2010

Greening The Curriculum: Augmenting Engineering And Technology Courses With Sustainability Topics, Kurt A. Rosentrater, Elif Kongar

Kurt A. Rosentrater

Duties of engineers and technologists often entail designing and implementing solutions to problems. It is their responsibility to be cognizant of the impacts of their designs on and thus, their accountability to society in general. They must also be aware of subsequent effects upon the environment. They need to be able to concurrently satisfy these often competing priorities as well as constraints specific to the technical challenges at hand. Responding to these contending forces are the growing fields of green engineering and sustainable engineering. Both of these areas encompass many concepts, ideas and tools all of which are essential for …

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Symmetries Of The Central Vestibular System: Forming Movements For Gravity And A Three-Dimensional World, Gin Mccollum, Douglas A. Hanes Jan 2010

Symmetries Of The Central Vestibular System: Forming Movements For Gravity And A Three-Dimensional World, Gin Mccollum, Douglas A. Hanes

Gin McCollum

Intrinsic dynamics of the central vestibular system (CVS) appear to be at least partly determined by the symmetries of its connections. The CVS contributes to whole-body functions such as upright balance and maintenance of gaze direction. These functions coordinate disparate senses (visual, inertial, somatosensory, auditory) and body movements (leg, trunk, head/neck, eye). They are also unified by geometric conditions. Symmetry groups have been found to structure experimentally-recorded pathways of the central vestibular system. When related to geometric conditions in three-dimensional physical space, these symmetry groups make sense as a logical foundation for sensorimotor coordination.

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Phase-Linking And The Perceived Motion During Off-Vertical Axis Rotation, Jan E. Holly, Scott J. Wood, Gin Mccollum Jan 2010

Phase-Linking And The Perceived Motion During Off-Vertical Axis Rotation, Jan E. Holly, Scott J. Wood, Gin Mccollum

Gin McCollum

Human off-vertical axis rotation (OVAR) in the dark typically produces perceived motion about a cone, the amplitude of which changes as a function of frequency. This perception is commonly attributed to the fact that both the OVAR and the conical motion have a gravity vector that rotates about the subject. Little-known, however, is that this rotating-gravity explanation for perceived conical motion is inconsistent with basic observations about self-motion perception: (a) that the perceived vertical moves toward alignment with the gravito-inertial acceleration (GIA) and (b) that perceived translation arises from perceived linear acceleration, as derived from the portion of the GIA …

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A Closer Look At The Relative Age Effect In The National Hockey League, Vittorio Addona, P. A. Yates Jan 2010

A Closer Look At The Relative Age Effect In The National Hockey League, Vittorio Addona, P. A. Yates

Vittorio Addona

No abstract provided.

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Quantifying The Effect Of Performance-Enhancing Drug Use On Fastball Velocity In Major League Baseball, Vittorio Addona, J. Roth Jan 2010

Quantifying The Effect Of Performance-Enhancing Drug Use On Fastball Velocity In Major League Baseball, Vittorio Addona, J. Roth

Vittorio Addona

No abstract provided.

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Gibbs Sampling For A Bayesian Hierarchical General Linear Model, Alicia A. Johnson, Galin L. Jones Jan 2010

Gibbs Sampling For A Bayesian Hierarchical General Linear Model, Alicia A. Johnson, Galin L. Jones

Alicia A. Johnson

No abstract provided.

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Forced Patterns Near A Turing-Hopf Bifurcation, Chad M. Topaz, Anne Catlla Jan 2010

Forced Patterns Near A Turing-Hopf Bifurcation, Chad M. Topaz, Anne Catlla

Chad M. Topaz

We study time-periodic forcing of spatially-extended patterns near a Turing-Hopf bifurcation point. A symmetry-based normal form analysis yields several predictions, including that (i) weak forcing near the intrinsic Hopf frequency enhances or suppresses the Turing amplitude by an amount that scales quadratically with the forcing strength, and (ii) the strongest effect is seen for forcing that is detuned from the Hopf frequency. To apply our results to specific models, we perform a perturbation analysis on general two-component reaction-diffusion systems, which reveals whether the forcing suppresses or enhances the spatial pattern. For the suppressing case, our results explain features of previous …

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The Stellar And Gaseous Contents Of The Orion Dwarf Galaxy, John M. Cannon, Korey Haynes, Hans Most, John J. Salzer, Kaitlin Haugland, Jillian Scudder, Arthur Sugden, Jacob Weindling Jan 2010

The Stellar And Gaseous Contents Of The Orion Dwarf Galaxy, John M. Cannon, Korey Haynes, Hans Most, John J. Salzer, Kaitlin Haugland, Jillian Scudder, Arthur Sugden, Jacob Weindling

John Cannon

No abstract provided.

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