Digital Commons Network^™

Isolation Of Cancer Stem Cells From Adult Glioblastoma Multiforme, Xianpeng Yuan, James Curtin, Yizhi Xiong, Gentao Liu, Sebastian Waschsmann-Hogiu, Daniel Farkas, Keith Black, John Yu

Articles

Glioblastoma multiforme (GBM) is the most common adult primary brain tumor and is comprised of a heterogeneous population of cells. It is unclear which cells within the tumor mass are responsible for tumor initiation and maintenance. In this study, we report that brain tumor stem cells can be identified from adult GBMs. These tumor stem cells form neurospheres, possess the capacity for self-renewal, express genes associated with neural stem cells (NSCs), generate daughter cells of different phenotypes from one mother cell, and differentiate into the phenotypically diverse populations of cells similar to those present in the initial GBM. Having a …

Pierre Rolland: Ireland's First Michelin Star Chef, Máirtín Mac Con Iomaire

Articles

This article profiles French master chef Pierre Rolland, who came to Ireland as chef de cuisine in the Russell Hotel and trained a generation of Irish chefs.

Emit: An Apparatus To Test Time Reversal Invariance In Polarized Neutron Decay, H. P. Mumm, A. Garcia, L. Grout, M. Howe, L. P. Parazzoli, R. G. H. Robertson, K. M. Sundqvist, J. F. Wilkerson, S. J. Freedman, B. K. Fujikawa, L. J. Lising, M. S. Dewey, J. S. Nico, A. K. Thompson, T. E. Chupp, R. L. Cooper, K. P. Coulter, S. R. Hwang, R. C. Welsh, L. J. Broussard, C. A. Trull, F. E. Wietfeldt, Gordon L. Jones

Articles

We describe an apparatus used to measure the triple-correlation term (D (σ) over cap (n).p(e)xp(nu)) in the beta decay of polarized neutrons. The D coefficient is sensitive to possible violations of time reversal invariance. The detector has an octagonal symmetry that optimizes electron-proton coincidence rates and reduces systematic effects. A beam of longitudinally polarized cold neutrons passes through the detector chamber, where a small fraction undergo beta decay. The final-state protons are accelerated and focused onto arrays of cooled semiconductor diodes, while the coincident electrons are detected using panels of plastic scintillator. Details regarding the design and performance of the …

The V1647 Orionis (Iras 05436–0007) Protostar And Its Environment, Peregrine M. Mcgehee, J. Allyn Smith, Arne A. Henden, Michael Richmond, Gillian R. Knapp, Douglas P. Finkbeiner, J. Brinkmann

Articles

We present Sloan Digital Sky Survey and United States Naval Observatory observations of the V1647 Ori protostar and surrounding field near NGC 2068. V1647 Ori, the likely driving source for HH 23, brightened significantly in November 2003. Analysis of SDSS imaging acquired in November 1998 and February 2002 during the quiescent state, recent USNO photometry, and published 2MASS and Gemini data shows that the color changes associated with brightening suggest an EXor outburst rather than a simple dust clearing event.

The Acs Virgo Cluster Survey. Xi. The Nature Of Diffuse Star Clusters In Early-Type Galaxies, Eric Peng, Patrick Côté, Andrés Jordán, John P. Blakeslee, Laura Ferrarese, Simona Mei, Michael J. West, David Merritt, Milos Milosavljević, John L. Tonry

Articles

We use HST/ACS imaging of 100 early-type galaxies in the ACS Virgo Cluster Survey to investigate the nature of diffuse star clusters (DSCs). Compared to globular clusters (GCs), these star clusters have moderately low luminosities (MV > −8) and a broad distribution of sizes (3 < rh < 30 pc), but they are principally characterized by their low mean surface brightnesses which can be more than three magnitudes fainter than a typical GC (µg > 20 mag arcsec−2). The median colors of diffuse star cluster systems are red, 1.1 < g − z < 1.6, which is redder than metal-rich GCs and often as red as the galaxy itself. Most DSC systems thus have mean ages older than 5 Gyr or else have super-solar metallicities implying that diffuse star clusters are likely to be long-lived, surviving for significant fraction of a Hubble time. We find that 12 galaxies in our sample contain a significant excess of diffuse star cluster candidates. Nine of them are morphologically classified as lenticulars (S0s), and five of them visibly contain dust. We also find a substantial population of DSCs in the halo of the giant elliptical M49, associated with the companion galaxy VCC 1199. Most DSC systems appear to be both aligned with the galaxy light and associated with galactic disks, but at the same time many lenticular galaxies do not host substantial DSC populations, and environment and clustercentric radius do not appear to be good predictors of their existence. Diffuse star clusters in our sample share similar characteristics to those identified in other nearby lenticular, spiral, and dwarf galaxies. Unlike luminous GCs, whose sizes are constant with luminiosity, DSCs are bounded at the bright end by an envelope of nearly constant surface brightness. We suggest that populations of diffuse star clusters preferentially form, survive, and coevolve with galactic disks. Their properties are broadly consistent with those of merged star cluster complexes, and we note that despite being 3–5 magnitudes brighter than DSCs, ultra-compact dwarfs have similar surface brightnesses. The closest Galactic analogs to the DSCs are the old open clusters. We suggest that if a diffuse star cluster population did exist in the disk of the Milky Way, it would be very difficult to find.

How Well Can People Use Different Color Attributes?, Hongqin Zhang, Ethan Montag

Articles

Two psychophysical experiments were conducted to analyze the role of color attributes in simple tasks involving color matching and discrimination. In Experiment I observers made color matches using three different adjustment control methods. The results showed that the Lightness, Chroma, Hue (LCH) and the Lightness, redness/greenness, blueness/yellowness ({L, r/g, y/b}) adjustment controls elicited significantly better performance than the display RGB controls in terms of both accuracy and time, but were not significantly different from each other. Expert observers performed significantly better than naive observers in terms of accuracy. Experiment II was a replication and extension of Melgosa, et al.’s experiment …

Supermassive Black Holes In Active Galactic Nuclei. Ii. Calibration Of The Black Hole Mass-Velocity Dispersion Relationship For Active Galactic Nuclei, Christopher A. Onken, Laura Ferrarese, David Merritt, Bradley M. Peterson, Richard W. Pogge, Marianne Vestergaard, Amri Wandel

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We calibrate reverberation-based black hole masses in active galactic nuclei (AGNs) by using the correlation between black hole mass, MBH, and bulge/spheroid stellar velocity dispersion, σ[sigma]∗. We use new measurements of σ[sigma]∗ for 6 AGNs and published velocity dispersions for 10 others, in conjunction with improved reverberation mapping results, to determine the scaling factor required to bring reverberation-based black hole masses into agreement with the quiescent galaxy MBH–σ[sigma]∗ relationship. The scatter in the AGN BH masses is found to be less than a factor of 3. The current observational uncertainties preclude use of the scaling factor to discriminate between broad-line …

The Acs Virgo Cluster Survey. Ii. Data Reduction Procedures, Andrés Jordán, John P. Blakeslee, Eric W. Peng, Simona Mei, Patrick Côté, Laura Ferrarese, John L. Tonry, David Merritt, Miloš Milosavljević, Michael J. West

Articles

The ACS Virgo Cluster Survey is a large program to carry out multi-color imaging of 100 early-type members of the Virgo Cluster using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. Deep F475W and F850LP images (≈ SDSS g and z) are being used to study the central regions of the program galaxies, their globular cluster systems, and the three-dimensional structure of Virgo itself. In this paper, we describe in detail the data reduction procedures used for the survey, including image registration, drizzling strategies, the computation of weight images, object detection, the identification of globular cluster candidates, …

A Classification Of Tournaments Having An Acyclic Tournament As A Minimum Feedback Arc Set, Garth Isaak, Darren Narayan

Articles

Given a tournament with an acyclic tournament as a feedback arc set we give necessary and sufficient conditions for this feedback arc set to have minimum size.

High-Resolution Slant-Angle Scene Generation And Validation Of Concealed Targets In Dirsig, Kris E. Barcomb, John Schott, Scott D. Brown, Timothy J. Hattenberger

Articles

Traditionally, synthetic imagery has been constructed to simulate images captured with low resolution, nadirviewing sensors. Advances in sensor design have driven a need to simulate scenes not only at higher resolutions but also from oblique view angles. The primary efforts of this research include: real image capture, scene construction and modeling, and validation of the synthetic imagery in the reflective portion of the spectrum. High resolution imagery was collected of an area named MicroScene at the Rochester Institute of Technology using the Chester F. Carlson Center for Imaging Science’s MISI and WASP sensors using an oblique view angle. Three Humvees, …

Surface And Buried Landmine Scene Generation And Validation Using The Digital Imaging And Remote Sensing Image Generation Model, Erin D. Peterson, Scott D. Brown, Timothy J. Hattenberger, John R. Schott

Articles

Detection and neutralization of surface-laid and buried landmines has been a slow and dangerous endeavor for military forces and humanitarian organizations throughout the world. In an effort to make the process faster and safer, scientists have begun to exploit the ever-evolving passive electro-optical realm, both from a broadband perspective and a multi or hyperspectral perspective. Carried with this exploitation is the development of mine detection algorithms that take advantage of spectral features exhibited by mine targets, only available in a multi or hyperspectral data set. Difficulty in algorithm development arises from a lack of robust data, which is needed to …

Information Seeking And Students Studying For Professional Careers: The Cases Of Enginerering And Law Students In Ireland, Gillian Kerins, Ronan Madden, Crystal Fulton

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This paper reports the results of two empirical studies which explored the information seeking behaviour of engineering and law students in Ireland. Findings reveal similar patterns in the information seeking behaviour between students studying to become professionals and information seeking patterns of these groups identified in the Leckie et al. model. Students learned their information seeking strategies, including effective and less effective approaches, from educators. Mis-perceptions of the role and value of libraries and information professionals in their studies were common, and as a result, students often adopted information seeking strategies that excluded libraries and library staff. The two studies …

Structural Characterisation Of A Sol-Gel Copolymer Synthesised From Aliphatic And Aromatic Alkoxysilanes Using 29si-Nmr Spectroscopy, Mohamed Oubaha, M. Dubois, B. Murphy, P. Etienne

Articles

A hybrid organic-inorganic material was prepared from the hydrolytic co-condensation of 3- trimethoxysilylpropylmethacrylate (MAPTMS) and diphenyldiethoxysilane (DPHDES). The synthesis was performed in three steps: (1) MAPTMS pre-hydrolysis, (2) addition of DPHDES, and (3) further hydrolysis of the obtained mixture. ²⁹ Si nuclear magnetic resonance spectroscopy was used to characterise the structural evolution of the mineral network during the synthesis. It revealed the catalytic effect of DPHDES on the condensation reaction of silanol groups, initially observed for pre-hydrolysed MAPTMS. In addition, it was clearly demonstrated that the formation of the highest condensed species of the aromatic oligomers (D₂ species) occurred …

A Novel Brdf Measurement Technique With Spatial Resolution-Dependent Spectral Variance, James Ii Shell, Carl Salvaggio, John Schott

Articles

Overhead spectral imaging has enabled a variety of quantitative remote sensing techniques. However, the derived surface reflectance upon which these techniques rely is generally directional and dependent upon the incident solar and receiving detector angles. The bidirectional reflectance distribution function (BRDF) is becoming increasingly important with the development of non-nadir, multi-angle systems. A BRDF measurement approach in the visible to near infrared is described which is suitable for field use. An imaging technique measures BRDF but also enables the generation of the BRDF variability, or the bidirectional reflectance variance function (BRVF). From the measurements, the BRVF and spectral correlation statistics …

Stark Width And Shift Of The Neutral Argon 425.9 Nm Spectral Line, Vladimir Milosavljevic, Vida Zigman, Stevan Djenize

Articles

The Stark parameters, the width (W) and the shift (d), of the neutral argon (Ar I) 425.9 nm spectral line have been studied in a linear, low-pressure, optically thin pulsed arc discharge. The line shapes are measured in three different plasmas at about 16,000 K electron temperature (T) and about 7.0×10²² m⁻³ electron density (N). The separate electron and ion contributions to the total Stark width (W_t), i.e. W_e and W_i, as well as to the total Stark shift (d_t), i.e. …

Image Quality Analysis Of A Spectra-Radiometric Sparse-Aperture Model, Noah R. Block, Robert Introne, John R. Schott

Articles

Sparse aperture (SA) telescopes represent a promising technology to increase the effective diameter of an optical system while reducing overall weight and stowable size. Although conceptually explored in the literature for decades, the technology has only recently matured to the point of being reasonably considered for certain applications. In general, a sparse aperture system consists of an array of sub-apertures that are phased to synthesize a larger effective aperture. The models used to date to create predictions of sparse aperture imagery typically make use of a “gray world” assumption, where the input is a resampled black and white panchromatic image. …

On The Dressing Method For The Generalised Zakharov-Shabat System, Rossen Ivanov

Articles

The dressing procedure for the Generalised Zakharov-Shabat system is well known for systems, related to sl(N) algebras. We extend the method, constructing explicitly the dressing factors for some systems, related to orthogonal and symplectic Lie algebras. We consider ’dressed’ fundamental analytical solutions with simple poles at the prescribed eigenvalue points and obtain the corresponding Lax potentials, representing the soliton solutions for some important nonlinear evolution equations.

N-Body Growth Of A Bahcall-Wolf Cusp Around A Black Hole, Miguel Preto, David Merritt, Rainer Spurzem

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We present a clear N-body realization of the growth of a Bahcall-Wolf f µE^1/4 (µr^−7/4) density cusp around a massive object (“black hole”) at the center of a stellar system. Our N-body algorithm incorporates a novel implementation of Mikkola-Aarseth chain regularization to handle close interactions between star and black hole particles. Forces outside the chain were integrated on a GRAPE-6A/8 special-purpose computer with particle numbers up to N = 0.25×10^6. We compare our N-body results with predictions of the isotropic Fokker-Planck equation and verify that the time dependence of the density (both configuration and phase-space) predicted by the Fokker-Planck equation …

20 Square Per Inch Graph Paper For Photographic Applications, Andrew Davidhazy

Articles

Admittedly this is not an "article" but it is hopefully something that some photography student, teacher or practitioner will find useful when they can't immediately locate 20 square per inch graph paper onto which to plot (at .4 log H or Density units per inch) film or paper characteristic curves.

Identification And Detection Of Gaseous Effluents From Hyperspectral Imagery Using Invariant Algorithms, Erin M. O'Donnell, David W. Messinger, Carl Salvaggio, John Schott

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The ability to detect and identify effluent gases is, and will continue to be, of great importance. This would not only aid in the regulation of pollutants but also in treaty enforcement and monitoring the production of weapons. Considering these applications, finding a way to remotely investigate a gaseous emission is highly desirable. This research utilizes hyperspectral imagery in the infrared region of the electromagnetic spectrum to evaluate an invariant method of detecting and identifying gases within a scene. The image is evaluated on a pixel-by-pixel basis and is studied at the subpixel level. A library of target gas spectra …

Comparison Of Basis-Vector Selection Methods For Target And Background Subspaces As Applied To Subpixel Target Detection, Peter Bajorski, Emmett J. Ientilucci, John Schott

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This paper focuses on comparing three basis-vector selection techniques as applied to target detection in hyperspectral imagery. The basis-vector selection methods tested were the singular value decomposition (SVD), pixel purity index (PPI), and a newly developed approach called the maximum distance (MaxD) method. Target spaces were created using an illumination invariant technique, while the background space was generated from AVIRIS hyperspectral imagery. All three selection techniques were applied (in various combinations) to target as well as background spaces so as to generate dimensionally-reduced subspaces. Both target and background subspaces were described by linear subspace models (i.e., structured models). Generated basis …

Temporal Variations In The Apparent Emissivity Of Various Materials, Carl Salvaggio, David P. Miller

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Spectral emissivity measurements gathered in the longwave infrared region of the spectrum during a recent airborne hyperspectral data collection experiment indicated that the spectral emissivity of certain organic polymers changed by as much as 10% throughout the day. Inorganic and many other organic materials that were measured at the same time during this experiment showed no change. As this was an unexpected event, a subsequent experiment was designed to make emissivity measurements of several organic and inorganic materials over a 24-hour period/diurnal cycle. The results from this experiment confirmed that certain materials showed a significant spectral emissivity variation over this …

Fibonacci And Lucas Numbers As Tridiagonal Matrix Determinants, Nathan D. Cahill, Darren Narayan

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There are many known connections between determinants of tridiagonal matrices and the Fibonacci and Lucas numbers.

De Facto Custodians: A Response To The Needs Of Informal Kin Caregivers?, Elizabeth Brandt

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No abstract provided.

Where Does Ap(E)L Fit In Higher Education?, Anne Murphy

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On an EU policy level the paper acknowledges the impact on thinking about AP(E)L as a result of the agreement of common European principles for validation of non-formal and in-formal learning in 2004 at the Dublin Conference during Ireland’s presidency of the EU (note 1).This conference also addressed the possible areas of agreement across vocational education and training (VET) and higher education (HE) on contiguous issues such as a common European Qualification Framework, common arrangements for credit transfer and common arrangements for quality assurance. Additionally, the paper is written contemporaneously with the introduction of such mechanisms as the Europass, European …

Cooking Online: Investigating The Effectiveness Of Providing Online Support Material To Students On A Professional Cookery Apprenticeship Course, Nuala Harding

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Having worked as a lecturer for five years, I was given the opportunity to undertake the postgraduate diploma in third-level learning and teaching at the Technological University Dublin. The elective I chose as part of this course was online learning. The requirement to compile a reflective journal during the module has provided the catalyst for me to write this paper. This Paper describes work in progress for proposed research within the Department of Hospitality, Tourism and Leisure Studies in Athlone Institute of Technology (AIT). The purpose of this research is to investigate the feasibility of providing and the effectiveness of …

They Don't Really Want To Know Us: Experiences And Perceptions Of International Students At The Technological University Dublin, Almut Schlepper

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This paper seeks to explore the experiences and perceptions of international, non-EU students at the Technological University Dublin. My interest in the subject derives from my work as a lecturer at a college with an increasing number of international students and from my participation as a student on a course which made me appreciate the value of a diverse student and lecturer body. The sample of the survey I carried out included international students and lecturers at one campus of the Technological University Dublin. While the results indicated that international students are just as heterogeneous as Irish students, they are …

Reaction Thresholds In Doubly Special Relativity, Daniel Heyman '03, F. Hinterleitner, Seth Major

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Two theories of special relativity with an additional invariant scale, “doubly special relativity,” are tested with calculations of particle process kinematics. Using the Judes-Visser modified conservation laws, thresholds are studied in both theories. In contrast with some linear approximations, which allow for particle processes forbidden in special relativity, both the Amelino-Camelia and Magueijo-Smolin frameworks allow no additional processes. To first order, the Amelino-Camelia framework thresholds are lowered and the Magueijo-Smolin framework thresholds may be raised or lowered.

Core Formation By A Population Of Massive Remnants, David Merritt, Slawomir Piatek, Simon Portegies Zwart, Marc Hemsendorf

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Core radii of globular clusters in the Large and Small Magellanic Clouds show an increasing trend with age. We propose that this trend is a dynamical effect resulting from the accumulation of massive stars and stellarmass black holes at the cluster centers. The black holes are remnants of stars with initial masses exceeding ∼ 20 - 25M⊙; as their orbits decay by dynamical friction, they heat the stellar background and create a core. Using analytical estimates and N-body experiments, we show that the sizes of the cores so produced and their growth rates are consistent with what is observed. We …

Investigation Of The Diffusion Processes In Self-Processing Acrylamide-Based Photopolymer System, Izabela Naydenova, Raghavendra Jallapuram, Robert Howard, Suzanne Martin, Vincent Toal

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Results from the investigation of the diffusion processes in a dry acrylamide-based photopolymer system are presented. The investigation is carried out in the context of experimental work on optimization of the high spatial frequency response of the photopolymer. Tracing the transmission holographic grating dynamics at short times of exposure is utilized to measure diffusion coefficients. The results reveal that two different diffusion processes contribute with opposite sign to the refractive index modulation responsible for the diffraction grating build up. Monomer diffusion from dark to bright fringe areas increases the refractive index modulation. It is characterized with diffusion constant D0=1.6E-7 cm2/s. …