cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Evidence for variable outflows in the Young Stellar Object V645 Cygni
Creators: name: Clarke, A. J.
name: Lumsden, S. L.
name: Oudmaijer, R. D.
name: Busfield, A. L.
name: Hoare, M. G.
name: Moore, T. J. T.
name: Sheret, T. L.
name: Urquhart, J. S.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: As part of the Red MSX Source Survey of Massive Young Stellar Objects (MYSOs) we have conducted multi-wavelength follow up observations of the well-known object V645 Cygni. We present our data on this object, whose near-infrared spectrum is exceptional and place these in context with previous observations. Our observations of V645 Cyg included near/mid infrared imaging observations, 13CO 2-1 line observations and high signal-to-noise velocity resolved near-infrared spectroscopy. The spectrum shows P-Cygni hydrogen Brackett emission, consistent with a high velocity stellar wind. A red-shifted emission component to a number of near-IR emission lines was also uncovered. This is associated with a similar component in the H alpha line. V645 Cyg is also found to have variable CO first overtone bandhead emission. The data clearly indicate that the outflow of V645 Cyg is variable. The unidentified feature in a previously published optical spectrum is identified with a receding outflow at 2000 km per second. The nature of this feature, which is found in hydrogen and helium atomic lines and CO molecular lines remains a puzzle.
description: 7 pages including 4 figures. Accepted for publication in A&A
Gross Theory Model for Neutrino-Nucleus Cross Section
Creators: name: Samana, A. R.
name: Barbero, C. A.
name: Duarte, S. B.
name: Dimarco, A. J.
name: Krmpotić, F.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The nuclear gross theory, originally formulated by Takahashi and Yamada for the $β$-decays, is applied for the electronic-neutrino nucleus reactions, employing a more realistic description to the energetics of the Gamow-Teller resonances. The model parameters are gauged from the most recent experimental data, both for $β^-$ decay and electron-capture, separately for even-even, even-odd, odd-odd, odd-even nuclei. The numerical estimates for neutrino-nucleus cross sections agree fairly well with previous evaluations done within the framework of microscopic models. The formalism presented here can be extended to the heavy nuclei mass region, where weak processes are quite relevant, which is of astrophysical interest because of its applications in supernova explosive nucleosynthesis.
description: 21 pages, 9 figures, accepted for publication in New Journal of Physics
Magnetic confinement of the solar tachocline
Creators: name: Brun, A. S.
name: Zahn, J. -P.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We study the physics of the solar tachocline and related MHD instabilities. We have performed 3-D MHD simulations of the solar radiative interior to check whether a fossil magnetic field is able to prevent the spread of the tachocline. Starting with a purely poloidal magnetic field and a latitudinal shear meant to be imposed by the convection zone at the top of the radiation zone, we have investigated the interactions between magnetic fields, rotation and shear, using the spectral code ASH on massive parallel supercomputers. In all cases we have explored, the fossil field diffuses outward and ends up connecting with the convection zone, whose differential rotation is then imprinted at latitudes above 40 deg throughout the radiative interior, according to Ferraro's law of isorotation. Rotation remains uniform in the lower latitude region which is contained within closed field lines. We find that the meridional flow cannot stop the inward progression of the differential rotation. Further, we observe the development of non-axisymmetric magnetohydrodynamic instabilities, first due to the initial poloidal configuration of the fossil field, and later to the toroidal field produced by shearing the poloidal field through the differential rotation. We do not find dynamo action as such in the radiative interior, since the mean poloidal field is not regenerated. But the instability persists during the whole evolution, while slowly decaying with the mean poloidal field. According to our numerical simulations, a fossil magnetic field cannot prevent the radiative spread of the tachocline, and thus it is unable to enforce uniform rotation in the radiation zone. Neither can the observed thinness of that layer be invoked as a proof for such an internal fossil magnetic field.
description: 12 pages, 8 color figures (low res), published in A&A, october 2006
Using swimming speed and morphological attributes of fish derived from video image analysis to assess grilse proportion and segregation in mixed population of maturing and non-maturing Atlantic salmon (Salmo salar L.) reared in sea cage
Creators: name: Boucher, Eric Louis
Publisher: name: University of British Columbia
Year: 2009

description: More effective ways to manage mixed populations of maturing and non-maturing Atlantic salmon are needed, and a method to predict the percentage of maturing salmon would be ideal. Maturing fish are known to swim slower and have a larger condition factor (K) than non-maturing fish, and if differences are large, bimodality could be evident in swimming speed and K factor data collected from mixed populations, and used to predict the grilse (maturing salmon) percentage. To test this hypothesis, two positions within the swimming aggregation were video recorded before and after the fish were fed using a stereo camera system within commercial salmon farming cages. From recorded images, swimming speed and morphological attributes were determined. The expected bimodal distributions were not observed; all variables showed a normal distribution with a single mode. Positional and temporal variations in swimming speed and size measurements were found. The average swimming speed was generally lower and the K factor higher in the upper section of the swimming aggregation. Furthermore, the swimming speed and the condition factor were noted to be respectively higher and lower before the feeding event. It was surmised that grilse segregated themselves from the rest of the population, and / or differences in swimming speed and other attributes between grilse and non-maturing salmon were too small to statistically substantiate bimodality in the data sets. Results provide insight into the relative importance of early grilse detection and removal in feeding management.
Spherical collapse with dark energy
Creators: name: Maor, Irit
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: I discuss the work of Maor and Lahav [1], in which the inclusion of dark energy into the spherical collapse formalism is reviewed. Adopting a phenomenological approach, I consider the consequences of - a) allowing the dark energy to cluster, and, b) including the dark energy in the virialization process. Both of these issues affect the final state of the system in a fundamental way. The results suggest a potentially differentiating signature between a true cosmological constant and a dynamic form of dark energy. This signature is unique in the sense that it does not depend on a measurement of the value of the equation of state of dark energy.
description: To appear in the proceedings of the ``Peyresq Physics 10" Workshop, 19 - 24 June 2005, Peyresq, France
Polymer size in dilute solutions in the good-solvent regime
Creators: name: Caracciolo, Sergio
name: Mognetti, Bortolo Matteo
name: Pelissetto, Andrea
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We determine the density expansion of the radius of gyration, of the hydrodynamic radius, and of the end-to-end distance for a monodisperse polymer solution in good-solvent conditions. We consider the scaling limit (large degree of polymerization), including the leading scaling corrections. Using the expected large-concentration behavior, we extrapolate these low-density expansions outside the dilute regime, obtaining a prediction for the radii for any concentration in the semidilute region. For the radius of gyration, comparison with field-theoretical predictions shows that the relative error should be at most 5% in the limit of very large polymer concentrations.
description: 23 pages, 1 figure
Group Analysis of Nonlinear Fin Equations
Creators: name: Vaneeva, O. O.
name: Johnpillai, A. G.
name: Popovych, R. O.
name: Sophocleous, C.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mathematical Physics (math-ph)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences
subject: 58J70; 35K57; 35C05; 35A30

description: Group classification of a class of nonlinear fin equations is carried out exhaustively. Additional equivalence transformations and conditional equivalence groups are also found. They allow to simplify results of classification and further applications of them. The derived Lie symmetries are used to construct exact solutions of truly nonlinear equations for the class under consideration. Nonclassical symmetries of the fin equations are discussed. Adduced results amend and essentially generalize recent works on the subject [M. Pakdemirli and A.Z. Sahin, Appl. Math. Lett., 2006, V.19, 378-384; A.H. Bokhari, A.H. Kara and F.D. Zaman, Appl. Math. Lett., 2006, V.19, 1356-1340].
description: 6 pages
Convergence of a Grassmannian Gradient Descent Algorithm for Subspace Estimation From Undersampled Data
Creators: name: Zhang, Dejiao
name: Balzano, Laura
Publisher: name: My University
Year: 2022
Subjects: subject: Computer Science
subject: Electrical Engineering
subject: Engineering

description: Subspace learning and matrix factorization problems have great many applications in science and engineering, and efficient algorithms are critical as dataset sizes continue to grow. Many relevant problem formulations are non-convex, and in a variety of contexts it has been observed that solving the non-convex problem directly is not only efficient but reliably accurate. We discuss convergence theory for a particular method: first order incremental gradient descent constrained to the Grassmannian. The output of the algorithm is an orthonormal basis for a $d$-dimensional subspace spanned by an input streaming data matrix. We study two sampling cases: where each data vector of the streaming matrix is fully sampled, or where it is undersampled by a sampling matrix $A_t\in \mathbb{R}^{m\times n}$ with $m\ll n$. Our results cover two cases, where $A_t$ is Gaussian or a subset of rows of the identity matrix. We propose an adaptive stepsize scheme that depends only on the sampled data and algorithm outputs. We prove that with fully sampled data, the stepsize scheme maximizes the improvement of our convergence metric at each iteration, and this method converges from any random initialization to the true subspace, despite the non-convex formulation and orthogonality constraints. For the case of undersampled data, we establish monotonic expected improvement on the defined convergence metric for each iteration with high probability.
Use of the Metropolis algorithm to simulate the dynamics of protein chains
Creators: name: Tiana, G.
name: Sutto, L.
name: Broglia, R. A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Other Quantitative Biology (q-bio.OT)
subject: FOS: Biological sciences

description: The Metropolis implementation of the Monte Carlo algorithm has been developed to study the equilibrium thermodynamics of many-body systems. Choosing small trial moves, the trajectories obtained applying this algorithm agree with those obtained by Langevin's dynamics. Applying this procedure to a simplified protein model, it is possible to show that setting a threshold of 1 degree on the movement of the dihedrals of the protein backbone in a single Monte Carlo step, the mean quantities associated with the off-equilibrium dynamics (e.g., energy, RMSD, etc.) are well reproduced, while the good description of higher moments requires smaller moves. An important result is that the time duration of a Monte Carlo step depends linearly on the temperature, something which should be accounted for when doing simulations at different temperatures.
description: corrections to the text and to the figures
Effect of Dynamic Ions on Band Structure of Plasmon Excitations
Creators: name: Akbari-Moghanjoughi, M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: In this paper we develop a new method to study the plasmon energy band structure in multispecies plasmas. Using this method, we investigate plasmon dispersion band structure of different plasma systems with arbitrary degenerate electron fluid. The linearized Schrödinger-Poisson model is used to derive appropriate coupled pseudoforce system from which the energy dispersion structure is calculated. It is shown that the introduction of ion mobility, beyond the jellium (static ion) model with a wide plasmon energy band gap, can fundamentally modify the plasmon dispersion character leading to a new form of low-level energy band, due to the electron-ion band structure mixing. The effects ionic of charge state and chemical potential of the electron fluid on the plasmonic band structure indicate many new features and reveal the fundamental role played by ions in the phonon assisted plasmon excitations in the electron-ion plasma system. Moreover, our study reveals that ion charge screening has a significant impact on the plasmon excitations in ion containing plasmas. The energy band structure of pair plasmas confirm the unique role of ions on the plasmon excitations in many all plasma environments. Current research helps to better understand the underlying mechanisms of collective excitations in charged environment and the important role of heavy species on the elementary plasmon quasiparticles. The method developed in this research may also be extended for complex multispecies and magnetized quantum plasmas as well as to investigation the surface plasmon-polariton interactions in nanometallic structures.
description: 20 Pages 5 Figures
Using Automatic Word Sense Generation to generate a Semantic Lexicon
Creators: name: Pfeifer, Craig
Publisher: name: Maryland Shared Open Access Repository
Year: 2008
Subjects: Computer Science (0984)

description: Word sense discrimination is the process of distinguishing the number of unique senses of a target word in a given corpus. This thesis approaches the task of word sense discrimination as an unsupervised clustering problem and uses semantic and syntactic features not seen in the current literature. Using the features from the clusters, this thesis constructs a new lexicon entry for the target word.
Evolution of 3D Boson Stars with Waveform Extraction
Creators: name: Balakrishna, Jayashree
name: Bondarescu, Ruxandra
name: Daues, Gregory
name: Guzman, F. Siddhartha
name: Seidel, Edward
Publisher: name: arXiv
Year: 2006
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Numerical results from a study of boson stars under nonspherical perturbations using a fully general relativistic 3D code are presented together with the analysis of emitted gravitational radiation. We have constructed a simulation code suitable for the study of scalar fields in space-times of general symmetry by bringing together components for addressing the initial value problem, the full evolution system and the detection and analysis of gravitational waves. Within a series of numerical simulations, we explicitly extract the Zerilli and Newman-Penrose scalar $Ψ_4$ gravitational waveforms when the stars are subjected to different types of perturbations. Boson star systems have rapidly decaying nonradial quasinormal modes and thus the complete gravitational waveform could be extracted for all configurations studied. The gravitational waves emitted from stable, critical, and unstable boson star configurations are analyzed and the numerically observed quasinormal mode frequencies are compared with known linear perturbation results. The superposition of the high frequency nonspherical modes on the lower frequency spherical modes was observed in the metric oscillations when perturbations with radial and nonradial components were applied. The collapse of unstable boson stars to black holes was simulated. The apparent horizons were observed to be slightly nonspherical when initially detected and became spherical as the system evolved. The application of nonradial perturbations proportional to spherical harmonics is observed not to affect the collapse time. An unstable star subjected to a large perturbation was observed to migrate to a stable configuration.
description: 26 pages, 12 figures
Unsupervised Target Detection and Classification for Hyperspectral Imagery
Creators: name: Jiao, Xiaoli
Publisher: name: Maryland Shared Open Access Repository
Year: 2010
Subjects: Anomaly Detection and Classification
Automatic Target Generation Process (ATGP)
Linear Spectral Mixture Analysis (LSMA)
Orthogonal Subspace Projection(OSP)
Unsupervised Target Detection and Classification
Virtual Dimensionality (VD)

description: This dissertation presents unsupervised spectral target detection and classification from a statistical signal processing point of view in the sense that the image pixels can be categorized into two groups of spectral signatures; target of interest, characterized by high-order statistics, and background, characterized by 2nd order statistics, which can be suppressed to improve the performance for target detection. The knowledge used to perform unsupervised spectral target analysis is obtained directly from the data a posteriori without pre-assumed prior knowledge. In order to generate the spectral sample signatures in these two categories, least-squares based unsupervised target sample generation (UTSG) and background sample generation (UBSG) algorithms are developed to extract spectral signatures of interest for each category with stopping rules devised for both algorithms to decide the number of sample signatures to be extracted.
Unsupervised Object Category Recognition in Image Datasets
Creators: name: Joglekar, Ajay Jayant
Publisher: name: Maryland Shared Open Access Repository
Year: 2007
Subjects: unsupervised image categorization
unsupervised image classification
unsupervised object recognition
object recognition
image classification
unsupervised learning
expectation maximization
Computer Science (0984)

description: Supervised learning of objects in images has been studied extensively as has the problem of finding a distance metric between objects belonging to a limited number of categories for the purpose of classification. However, relatively little research has been done on unsupervised learning of object categories. Similarly generic; object recognition has only been explored in a limited manner. The main hurdle in both unsupervised learning of object categories and in generic; object recognition is the lack of a standard distance metric that can be used for classification of arbitrary objects. The aim of this research was two-fold. I wanted to study the methods of object recognition that modeled how humans learn to recognize objects. Further I wanted to study how these methods could be used to give a distance measure between images based on the objects in those images. The other goal of this research was to use a distance measure found from the literature study in developing an unsupervised object category recognition system. A system that gives good classification would prove the viability of the approach of using a distance measure between images in terms of objects, for unsupervised object category classification.
Suicide disparities across urban and suburban areas in the U.S.: A comparative assessment of socio-environmental factors using a data-driven predictive approach
Creators: name: Mukherjee, Sayanti
name: Wei, Zhiyuan
Publisher: name: arXiv
Year: 2020
Subjects: subject: Applications (stat.AP)
subject: FOS: Computer and information sciences

description: Disparity in suicide rates between urban and suburban/rural areas is growing, with rural areas typically witnessing higher suicide rates in the U.S. However, previous studies often ignored the effect of socio-environmental factors on the suicide rates and its regional disparity. To address these gaps, we propose a holistic data-driven framework to model the associations of social (demographic, socioeconomic) and environmental (climate) factors on suicide rates, and study the disparities across urban and suburban areas. Leveraging the county-level suicide data from 2000--2017 along with the socio-environmental features, we trained, tested and validated a suite of advanced statistical learning algorithms to identify, assess and predict the influence of key socio-environmental factors on suicide rates. Random forest outperformed all other models in terms of goodness-of-fit and predictive accuracy, and selected as the final model to make inferences. Our results indicate that population demographics is significantly associated with both urban and suburban suicide rates. We found that suburban population is more vulnerable to suicides compared to urban communities, with suburban suicide rate being particularly sensitive to unemployment rate and median household income. Our analysis revealed that suicide mortality is correlated to climate, showing that urban suicide rate is more sensitive to higher temperatures, seasonal-heating-degree-days and precipitation, while suburban suicide rate is sensitive to only seasonal-cooling-degree-days. This work provides deeper insights on interactions between key socio-environmental factors and suicides across different urbanized areas, and can help the public health agencies develop suicide prevention strategies to reduce the growing risk of suicides.
The $qqqq\bar q$ components and hidden flavor contributions to the baryon magnetic moments
Creators: name: an, C. S.
name: Li, Q. B.
name: Riska, D. O.
name: Zou, B. S.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The contributions from the $qqqq\bar q$ components to the magnetic moments of the octet as well as the $Δ^{++}$ and $Ω^-$ decuplet baryons are calculated for the configurations that are expected to have the lowest energy if the hyperfine interaction depends both on spin and flavor. The contributions from the $u\bar u$, $d\bar d$ and $s\bar s$ components are given separately. It is shown that addition of $qqqq\bar q$ admixtures to the ground state baryons can improve the overall description of the magnetic moments of the baryon octet and decuplet in the quark model without SU(3) flavor symmetry breaking, beyond that of the different constituent masses of the strange and light-flavor quarks. The explicit flavor (and spin) wave functions for all the possible configurations of the $qqqq\bar q$ components with light and strange $q\bar q$ pairs are given for the baryon and octet and decuplet. Admixtures of ~ 10% of the $qqqq\bar q$ configuration where the flavor-spin symmetry is $[4]_{FS}[22]_F[22]_S$, which is likely to have the lowest energy, in particular reduces the deviation from the empirical values of the magnetic moments of the $Σ^ -$ and the $Ξ^0$ compared with the quark model.
description: 17 pages
Unsupervised hyperspectral target detection
Creators: name: Liu, Wei-Min
Publisher: name: Maryland Shared Open Access Repository
Year: 2008
Subjects: Engineering, Electronics and Electrical (0544)
Anomaly detection
Virtual dimensionality
Orthogonal subspace projection

description: Due to significantly improved spectral resolution, hyperspectral imagery can now uncover many subtle materials and substances that cannot be identified a priori or by visual inspection. In this case unsupervised target detection becomes increasingly important in data analysis, specifically in surveillance applications where many unknown signal sources are of interest. This dissertation investigates this interesting area in addressing two major issues which are very challenging and yet to be explored. One is to design criteria for determining the number of targets of interest within the data to be processed. Despite the fact that a new concept of Virtual Dimensionality (VD) was recently developed for this purpose the VD estimation techniques are generally less adaptive or flexible to meet different applications. In order to expand the utility of the VD in versatile applications, two methods, Signal Subspace Estimate (SSE) and Neyman Pearson detection-based method, which are previously shown to be promising in estimation of the VD, are further extended by the other two methods. One is called Orthogonal Subspace Projection (OSP)-based VD which is derived from the SSE and NPD. The other is called Maximum OSP-based VD, which incorporated the Neyman-Pearson detection theory into the Maximum Orthogonal Complement Algorithm (MOCA). Both methods include free parameters to tune the sensitivity of the VD to different types of targets of interest in data analysis. The other major issue discussed in the dissertation is anomaly detection. Since there is no prior target knowledge available for the unsupervised target detection, the most commonly used approach to unsupervised target detection is anomaly detection. However, since the types of targets of interest are generally unknown, this dissertation develops a new anomaly detection approach, called Multiple Window Anomaly Detection (MWAD) which is particularly designed to detect various targets with different sizes. Within the context of the MWAD, several widely used anomaly detectors, such as RX detector developed by Reed and Yu and Dual Window Eigen Separation Transform (DWEST) developed by Known and Nasabadi, become its special cases. Finally, a brief summary and further discussion are provided to conclude this dissertation.
Power-laws and Non-Power-laws in Dark Matter Halos
Creators: name: Henriksen, R. N.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Simulated dark matter profiles are often modelled as a `NFW' density profile rather than a single power law. Recently, attention has turned to the rather rigorous power-law behaviour exhibited by the `pseudo phase-space density' of the dark matter halo, which is defined dimensionally in terms of the local density and velocity dispersion of the dark matter particles. The non-power-law behaviour of the density profile is generally taken to exclude simple scale-free, in-fall models; however the power-law behaviour of the `pseudo-density' is a counter indication. We argue in this paper that both behaviours may be at least qualitatively understood in terms of a dynamically evolving self-similarity, rather than the form for self-similar infall that is fixed by cosmological initial conditions. The evolution is likely due to collective relaxation such as that provided by the radial-orbit instability on large scales. We deduce, from a distribution function given by first order coarse-graining, both the NFW-type density profile and the power-law pseudo-density profile. The results are not greatly sensitive to variation about 3 in the power of the velocity dispersion used in the definition of the phase space pseudo-density. We suggest that the power 2 may create the more physical quantity, whose deviations from a power-law are a diagnostic of incomplete relaxation.
description: 31 pages, 4 figures
Ultrafast Dual-Gain-Media Nd:Glass Laser
Creators: name: Han, Song
Publisher: name: Maryland Shared Open Access Repository
Year: 2008
Subjects: Engineering, Electronics and Electrical(0544)

description: This dissertation presents an experimental demonstration of an ultrafast dual-gain-media Nd:glass laser. This laser contains both the Nd:fluorophosphate glass (Schott glass LG-810 ) and the Nd:silicate glass (Schott glass LG-680 ) in a single cavity. Record-short pulses of 34 fs were generated by Kerr-lens mode-locking from the dual-gain-media Nd:glass laser as a result of the overall gain broadening. Compared with the shortest pulses generated from a single-medium Nd:glass laser, the pulse was shortened by nearly a factor of 2. Neodymium-doped glass is characterized by inhomogeneous broadening and multiple Stark-split sub-transitions. This dissertation presents a comprehensive study of passive mode-locking of inhomogeneously broadened lasers. For a broadband inhomogeneously broadened laser, mode-locking becomes unstable when the lasing spectrum exceeds the maximum lockable spectrum. This mode-locking instability due to the insufficient gain filtering does not appear in homogeneously broadened lasers. The mode-locking by the pure self-amplitude modulation is essentially a phase-locking process. The soliton mode-locking resists best the impact of insufficient gain filtering, while the mode-locking under a strong self-phase modulation and positive group-delay dispersion is the weakest and a certain amount of gain filtering (narrowing) is necessary. A minimum unsaturated absorber loss is required for stable mode-locking in most situations. When the multiple Stark-split sub-transitions are involved in the laser gain, it generally broadens the overall gain linewidth and narrows the free-running spectrum. Those Stark-split sub-transitions located near the gain peak primarily affect the gain curvature and therefore how strong the gain filtering effect is. The free-running bandwidth is primarily determined by those Stark-split sub-transitions located within the inhomogeneous linewidth. In passive mode-locking, a larger GDD region of stable mode-locking exists as a result of the involvement of multiple Stark-split sub-transitions compared to the single-transition gain. When mode-locking strength is strong or GDD is small, the gain including the multiple Stark-split sub-transition can be approximated by a single-transition gain of which the homogeneous linewidth is equal to the effective homogeneous linewidth of the Stark-splitting gain.
On the detection of the progenitor of the type Ia supernova 2007on
Creators: name: Roelofs, Gijs
name: Bassa, Cees
name: Voss, Rasmus
name: Nelemans, Gijs
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present new Chandra X-ray observations and detailed astrometry of the field of the type Ia supernova 2007on, for which the detection of a likely progenitor in archival Chandra data was recently reported. No source is detected in the new Chandra images, taken six weeks after optical maximum. We calculate a 90-99% probability that any X-ray source near the position of the supernova (SN) is fainter than in the pre-outburst images, depending on the choice of aperture, which supports the identification of the archival X-ray source with the SN. Detailed astrometry of the X-ray and new optical images, however, gives an offset between the supernova and the measured X-ray source position of 1.15+/-0.27". Extensive simulations show that the probability of finding an offset of this magnitude is ~1%, equal to the (trial-corrected) probability of a chance alignment with any X-ray source in the field. This casts doubt on the identification of the X-ray source with the progenitor, although the scenario in which at least some of the observed X-rays are connected to the supernova may be the least unlikely based on all available data. After a brief review of the auxiliary evidence, we conclude that only future X-ray observations can shed further light on the proposed connection between the X-ray source and the progenitor of SN 2007on, and thus whether an accreting white dwarf scenario is truly favoured for this SN Ia.
description: Version accepted by MNRAS
Trustworthy Data Management in Pervasive Environments
Creators: name: Patwardhan, Anand
Publisher: name: Maryland Shared Open Access Repository
Year: 2007
Subjects: Computer Science (0984)

description: An era of computing is rapidly emerging where mobile agents autonomously retrieve and process information from various anchored and mobile sources from a pervasive environment. In this thesis, we have taken a holistic approach to protecting devices themselves and the underlying communication fabric that enables and sustains peer interactions. We address the challenges of trustworthy data management in distributed mobile systems where peers use and compete for access to a shared contention medium relying mostly on collaborative processes to achieve communication and information exchange. Limitations in individual capabilities subject to prevalent physical and energy constraints in the surrounding environment and the need to enhance them, necessitate collaborative interactions amongst peer devices. They do so by dynamically establishing peer-to-peer relationships to perform complex tasks leveraging available resources either shared amongst the peers or those present in the surrounding environment. However, mobile wireless devices lack the conventional protections afforded to their wired counterparts. Most of the conventional security paradigms and protection mechanisms available in wired networks are unsuitable or inapplicable in these open, mobile, and wireless environments. This thesis presents a systematic investigation of how devices can cope with the freedom of others, and mitigate risks by taking an approach of proactive vigilance in monitoring the environment and maintaining reputations. The main contributions of this work are a first of its kind actual implementation of an IPv6 based Intrusion Detection system for Mobile Ad Hoc networks integrated with a secure routing protocol, a data-intensive reputation management system, a policy-based security framework for governing mobile devices, and a framework for analyzing collaborative processes in such environments.
N-cadherin-mediated cell adhesion regulates proliferation and differentiation in the developing central nervous system
Creators: name: Chalasani, Kavita
Publisher: name: Maryland Shared Open Access Repository
Year: 2010
Subjects: beta-catenin
central nervous system
differentiation
N-cadherin
proliferation
Shh signaling

description: Cadherins play an important role in morphogenesis and have recently been implicated in the regulation of cell proliferation, however the mechanisms by which they function are poorly understood. In the vertebrate CNS, loss of N-cadherin (N-cad) lts in impaired neuroepithelial integrity. Zebrafish N-cad  mutants also exhibit a transient increase in neurons and in cell proliferation in the neural tube. Here, we investigate the cellular and molecular basis for this phenotype, using multiple N-cad les with distinct molecular properties. We confirm that cell proliferation is enhanced in N-cad nts, but contrary to previous findings, we observe that the increase is sustained over multiple stages of development. At the cellular level, loss of N-cad lts in a shorter cell cycle. Furthermore, we demonstrate that hyperproliferation is not linked to abnormal beta-catenin localization, suggesting that Wnt signaling is not increased. Our results indicate that components of Shh signaling namely, ptc1 gli1 upregulated in the dorsal region of N-cad ts. In addition, blocking Shh signaling rescues the hyperproliferation phenotype observed in N-cad nts suggesting that N-cad regulates cell division by limiting the range of Shh signaling. Despite an increase in the total number of neurons, the neuronal differentiation index is in fact reduced in N-cad nts, suggesting that the supernumerary neurons are produced as a result of overproliferation rather than enhanced differentiation. Consistent with this observation, the rate of cell cycle exit is unchanged. Intriguingly, we also observe that a small subset of N-cad mutant cells are double positive for mitotic and neuronal differentiation markers, suggesting a role for N-cad in coupling cell cycle exit and differentiation. These findings highlight the role of N-cad in regulating cell proliferation in the developing nervous system and reveal a novel function for N-cad in coupling cell cycle exit and differentiation.
Testosterone and competition in women and men
Creators: name: Wuehrmann, Elizabeth V.
Publisher: name: The University of Texas at Austin
Year: 2004
Subjects: Testosterone level
Competitive behaviors
Men and Women

description: High testosterone is linked to dominance and competitive behaviors, but that link is less clear in humans, particularly in women. High testosterone women may hesitate to compete because they may suffer negative social consequences for behaving dominantly. We hypothesized that women in general would perform better in a prosocial or cooperative competition vs. a traditional head-to-head condition, and that high testosterone women would perform particularly well in a prosocial competition. We also predicted that high testosterone males would perform best in a traditional competition than a prosocial one. We found that testosterone predicted performance in the competitive condition overall, with marginal between sex differences. Possible reasons for these findings include a change in women's attitudes about competition and different pathways to status among high and low testosterone women
First Results from the XMM-Newton Slew Survey
Creators: name: Read, Andrew
name: Saxton, Richard
name: Esquej, Pilar
name: Freyberg, Michael
name: Altieri, Bruno
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We have attempted to analyse all the available data taken by XMM-Newton as it slews between targets. This slew survey, the resultant source catalogue and the analysis procedures used are described in an accompanying paper. In this letter we present the initial science results from the survey. To date, detailed source-searching has been performed in three X-ray bands (soft, hard and total) in the EPIC-pn 0.2-12 keV band over ~6300 sq.degrees (~15% of the sky), and of order 4000 X-ray sources have been detected (~55% of which have IDs). A great variety of sources are seen, including AGN, galaxies, clusters and groups, active stars, SNRs, low- and high-mass XRBs and white dwarfs. In particular, as this survey constitutes the deepest ever hard-band 2-12 keV all-sky survey, a large number of hard sources are detected. Furthermore, the great sensitivity and low-background of the EPIC-pn camera are especially suited to emission from extended sources, and interesting spatial structure is observed in many supernova remnants and clusters of galaxies. The instrument is very adept at mapping large areas of the X-ray sky. Also, as the slew survey is well matched to the ROSAT all-sky survey, long-term variability studies are possible, and a number of extremely variable X-ray sources, some possibly due to the tidal disruption of stars by central supermassive black holes, have been discovered.
description: 4 Pages, 3 Figs, to appear in PASJ (2006) 58, No 6. Colour version available at http://www.star.le.ac.uk/~amr30/publications.html
Using Expert Traces to Reduce Training Time in Reinforcement Learning
Creators: name: Goldfinger, Joel David
Publisher: name: Maryland Shared Open Access Repository
Year: 2008
Subjects: Computer Science(0984)
Reinforcement Learning
Reward Shaping

description: Reinforcement learning algorithms are typically used to solve Markov decision problems. Using reinforcement learning to find an optimal or sub-optimal solution is a slow process. The use of prior knowledge can shorten the length of this task. In this thesis, we explore the use of expert traces to speed up this process. An expert trace is a record of the states visited and actions taken by an expert in a given domain, which is then used to reduce the training time of reinforcement learning. We demonstrate in a variety of domains significant improvements in learning when complementing reinforcement learning with expert traces.
Science Policy for an increasingly diverging Europe
Creators: name: Heitor, Manuel
Publisher: name: Università degli Studi di Milano
Year: 2015
Subjects: research policy; education policy;

description: This paper argues about the need for a revisited public policy framework giving priority to knowledge and technological change across the entire Europe, by discussing new cumulative data on R&D expenditure and the qualification of human resources across Europe. It takes a wide international comparison after a decade hit by recession and economic and budgetary problems, which shows an increasing internal divergence on knowledge investments across Europe, beyond the increasing gap between Europe as a whole and North America. As a result, the paper argues that new paradigms and conditions for responsible science and innovation policy across EU require the collective action of R&D institutions and a system approach to higher education, together with new initiatives towards international cooperation across an enlarged Europe.

Analysis shows that chronic backwardness in science and technology in many European peripheries, including in EU southern and eastern regions, have been significantly overcome over the last decade. Nevertheless, their growing scientific and technological capacity is now associated with an increasing vulnerability as a result of the growing international competition for qualified human resources. Additionally, the comparative analysis of levels of economic diversification and sophistication across Europe, suggests the need to insist on qualification and institutional strengthening. This should consider active public policies to attract and retain qualified human resources all over Europe, as well as considering public actions towards promoting new markets. The way in which the economic fabric may gain competitiveness and access to external markets may require enhancing the degree of internationalization of the scientific community and encouraging international knowledge and innovation networks.
description: RT. A Journal on Research Policy and Evaluation, Vol 3, No 1 (2015)
How does a protein search for the specific site on DNA: the role of disorder
Creators: name: Hu, Tao
name: Shklovskii, B. I.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Biomolecules (q-bio.BM)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Proteins can locate their specific targets on DNA up to two orders of magnitude faster than the Smoluchowski three-dimensional diffusion rate. This happens due to non-specific adsorption of proteins to DNA and subsequent one-dimensional sliding along DNA. We call such one-dimensional route towards the target "antenna". We studied the role of the dispersion of nonspecific binding energies within the antenna due to quasi random sequence of natural DNA. Random energy profile for sliding proteins slows the searching rate for the target. We show that this slowdown is different for the macroscopic and mesoscopic antennas.
description: 4 pages, 4 figures
title: A Program Transformation for Converting Java Assertions into Control-flow Statements
Creators: name: Caballero, Rafael
name: Hof, Vincent
name: Montenegro, Manuel
name: Kuchen, Herbert
Publisher: name: University of Muenster, Institutional Repository MIAMI
Year: 2024
Subjects: subject: 004 Computer science
subject: 330 Economics

description: We present a technique for checking the validity of Java assertions using an arbitrary automated
test-case generator. Our framework transforms the program by introducing code that detects
whether the assertion conditions are met by every direct and indirect method call within a certain
depth level. Then, any automated test-case generator can be used to look for input examples that
falsify the conditions. The program transformation ensures that the value obtained for these inputs
represents a path of method calls that ends with a violation of some assertion. We show experiments
with two different automatic test-case generators that demonstrate not just the applicability
of our proposal but also that we can get a better coverage than the same test-case generators
without our transformation.
description: Working Paper Sketch ..... 4
1 Introduction ..... 5
2 Conditions, Assertions, and Automated Test-Case Generation ..... 6
3 Program Transformation ..... 7
3.1 Java Syntax ..... 7
3.2 Flattening ..... 9
3.3 Program Transformation ..... 9
4 Inheritance ..... 15
5 Experiments ..... 15
6 Conclusions ..... 17
References ..... 19
Room-temperature ballistic transport in narrow graphene strips
Creators: name: Gunlycke, D.
name: Lawler, H. M.
name: White, C. T.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We investigate electron-phonon couplings, scattering rates, and mean free paths in zigzag-edge graphene strips with widths of the order of 10 nm. Our calculations for these graphene nanostrips show both the expected similarity with single-wall carbon nanotubes (SWNTs) and the suppression of the electron-phonon scattering due to a Dirichlet boundary condition that prohibits one major backscattering channel present in SWNTs. Low-energy acoustic phonon scattering is exponentially small at room temperature due to the large phonon wave vector required for backscattering. We find within our model that the electron-phonon mean free path is proportional to the width of the nanostrip and is approximately 70 $μ$m for an 11-nm-wide nanostrip.
description: 5 pages and 5 figures