Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Faculty Publications

Discipline
Institution
Keyword
Publication Year
File Type

Articles 3181 - 3210 of 9029

Full-Text Articles in Entire DC Network

Minerals In The Rhizosphere: Overlooked Mediators Of Soil Nitrogen Availability To Plants And Microbes, Andrea Jilling, Marco Keiluweit, Alexandra R. Contosta, Serita D. Frey, Joshua Schimel, Jorg Schnecker, Richard G. Smith, Lisa Tiemann, A. Stuart Grandy Jun 2018

Minerals In The Rhizosphere: Overlooked Mediators Of Soil Nitrogen Availability To Plants And Microbes, Andrea Jilling, Marco Keiluweit, Alexandra R. Contosta, Serita D. Frey, Joshua Schimel, Jorg Schnecker, Richard G. Smith, Lisa Tiemann, A. Stuart Grandy

Faculty Publications

Despite decades of research progress, ecologists are still debating which pools and fluxes provide nitrogen (N) to plants and soil microbes across different ecosystems. Depolymerization of soil organic N is recognized as the rate-limiting step in the production of bioavailable N, and it is generally assumed that detrital N is the main source. However, in many mineral soils, detrital polymers constitute a minor fraction of total soil organic N. The majority of organic N is associated with clay-sized particles where physicochemical interactions may limit the accessibility of N-containing compounds. Although mineral-associated organic matter (MAOM) has historically been considered a critical, …

Go to article

Energy-Constrained Two-Way Assisted Private And Quantum Capacities Of Quantum Channels, Noah Davis, Maksim E. Shirokov, Mark M. Wilde Jun 2018

Energy-Constrained Two-Way Assisted Private And Quantum Capacities Of Quantum Channels, Noah Davis, Maksim E. Shirokov, Mark M. Wilde

Faculty Publications

With the rapid growth of quantum technologies, knowing the fundamental characteristics of quantum systems and protocols is essential for their effective implementation. A particular communication setting that has received increased focus is related to quantum key distribution and distributed quantum computation. In this setting, a quantum channel connects a sender to a receiver, and their goal is to distill either a secret key or entanglement, along with the help of arbitrary local operations and classical communication (LOCC). In this work, we establish a general theory of energy-constrained, LOCC-assisted private and quantum capacities of quantum channels, which are the maximum rates …

Go to article

Neighbor And Height Effects On Crown Properties Associated With The Uniform-Stress Principle Of Stem Formation, Thomas J. Dean Jun 2018

Neighbor And Height Effects On Crown Properties Associated With The Uniform-Stress Principle Of Stem Formation, Thomas J. Dean

Faculty Publications

According to the uniform-stress principle of stem formation, the amount of leaf area a tree carries and the leverage it exerts on the stem determine the stem dimensions. Within an even-aged monoculture, the leaf area per tree and the leverage placed on the stem are functions of tree density and tree height. The uniform-stress principle presents the means to translate density effects on crown characteristics into stem dimensions and total standing volume. This approach is truly a top-down method of simulating growth tree and stand growth because leaf area and other crown properties must be determined before stem size and …

Go to article

Strong And Uniform Convergence In The Teleportation Simulation Of Bosonic Gaussian Channels, Mark M. Wilde Jun 2018

Strong And Uniform Convergence In The Teleportation Simulation Of Bosonic Gaussian Channels, Mark M. Wilde

Faculty Publications

In the literature on the continuous-variable bosonic teleportation protocol due to Braunstein and Kimble [Phys. Rev. Lett. 80, 869 (1998)PRLTAO0031-900710.1103/PhysRevLett.80.869], it is often loosely stated that this protocol converges to a perfect teleportation of an input state in the limit of ideal squeezing and ideal detection, but the exact form of this convergence is typically not clarified. In this paper, I explicitly clarify that the convergence is in the strong sense, and not the uniform sense, and furthermore that the convergence occurs for any input state to the protocol, including the infinite-energy Basel states defined and discussed here. I also …

Go to article

Enabling Autonomous Navigation For Affordable Scooters, Kaikai Liu, Rajathswaroop Mulky Jun 2018

Enabling Autonomous Navigation For Affordable Scooters, Kaikai Liu, Rajathswaroop Mulky

Faculty Publications

Despite the technical success of existing assistive technologies, for example, electric wheelchairs and scooters, they are still far from effective enough in helping those in need navigate to their destinations in a hassle-free manner. In this paper, we propose to improve the safety and autonomy of navigation by designing a cutting-edge autonomous scooter, thus allowing people with mobility challenges to ambulate independently and safely in possibly unfamiliar surroundings. We focus on indoor navigation scenarios for the autonomous scooter where the current location, maps, and nearby obstacles are unknown. To achieve semi-LiDAR functionality, we leverage the gyros-based pose data to compensate …

Go to article

Applied Computing For Behavioral And Social Sciences (Acbss) Minor, Farshid Marbouti, Valerie Carr, Belle Wei, Morris Jones, Amy Strage Jun 2018

Applied Computing For Behavioral And Social Sciences (Acbss) Minor, Farshid Marbouti, Valerie Carr, Belle Wei, Morris Jones, Amy Strage

Faculty Publications

The growing digital economy creates unprecedented demand for technical workers, especially those with both domain knowledge and technical skills. To meet this need, an ACBSS (Applied Computing for Behavioral and Social Sciences) minor degree has been developed by an interdisciplinary team of faculty at San José State University (SJSU). The minor degree comprises four courses: Python programming, algorithms and data structures, R programming, and culminating projects. The first ACBSS cohort started in Fall 2016 with 32 students, and the second cohort in Fall 2017 reached its capacity of 40 students, 62% of whom are female and 35% are underrepresented minority …

Go to article

Vehicle Tracking And Speed Estimation From Traffic Videos, Shuai Hua, Manika Kapoor, David Anastasiu Jun 2018

Vehicle Tracking And Speed Estimation From Traffic Videos, Shuai Hua, Manika Kapoor, David Anastasiu

Faculty Publications

The rapid recent advancements in the computation ability of everyday computers have made it possible to widely apply deep learning methods to the analysis of traffic surveillance videos. Traffic flow prediction, anomaly detection, vehicle re-identification, and vehicle tracking are basic components in traffic analysis. Among these applications, traffic flow prediction, or vehicle speed estimation, is one of the most important research topics of recent years. Good solutions to this problem could prevent traffic collisions and help improve road planning by better estimating transit demand. In the 2018 NVIDIA AI City Challenge, we combine modern deep learning models with classic computer …

Go to article

Photovoltaic System Optimization For An Austere Location Using Time Series Data, Torrey J. Wagner, Eric Lang, Warren Assink, Douglas S. Dudis Jun 2018

Photovoltaic System Optimization For An Austere Location Using Time Series Data, Torrey J. Wagner, Eric Lang, Warren Assink, Douglas S. Dudis

Faculty Publications

In this work we test experimental photovoltaic, storage and generator technologies and investigate their potential to meet austere location energy needs. After defining the energy requirements and insolation of a 1,100-person base, we develop a microgrid model and simulation. Cost optimizations were then performed using hourly time-series data to explore the cost and performance trade-space of a PV-battery-generator system. The work highlights the cost of resiliency and the dependencies of optimum system component sizes on duration and the fully burdened cost of fuel.

Go to article

The Montevideo Interpretation Of Quantum Mechanics: A Short Review, Rodolfo Gambini, Jorge Pullin Jun 2018

The Montevideo Interpretation Of Quantum Mechanics: A Short Review, Rodolfo Gambini, Jorge Pullin

Faculty Publications

The Montevideo interpretation of quantum mechanics, which consists of supplementing environmental decoherence with fundamental limitations in measurement stemming from gravity, has been described in several publications. However, some of them appeared before the full picture provided by the interpretation was developed. As such, it can be difficult to get a good understanding via the published literature. Here, we summarize it in a self-contained brief presentation including all its principal elements.

Go to article

Physics Potentials With The Second Hyper-Kamiokande Detector In Korea, K. Abe, Ke Abe, S. H. Ahn, H. Aihara, A. Aimi, R. Akutsu, C. Andreopoulos, I. Anghel, L. H.V. Anthony, M. Antonova, Y. Ashida, V. Aushev, M. Barbi, G. J. Barker, G. Barr, P. Beltrame, V. Berardi, M. Bergevin, S. Berkman, L. Berns, T. Berry, S. Bhadra, F. D.M. Blaszczyk, A. Blondel, S. Bolognesi, S. B. Boyd, A. Bravar, C. Bronner Jun 2018

Physics Potentials With The Second Hyper-Kamiokande Detector In Korea, K. Abe, Ke Abe, S. H. Ahn, H. Aihara, A. Aimi, R. Akutsu, C. Andreopoulos, I. Anghel, L. H.V. Anthony, M. Antonova, Y. Ashida, V. Aushev, M. Barbi, G. J. Barker, G. Barr, P. Beltrame, V. Berardi, M. Bergevin, S. Berkman, L. Berns, T. Berry, S. Bhadra, F. D.M. Blaszczyk, A. Blondel, S. Bolognesi, S. B. Boyd, A. Bravar, C. Bronner

Faculty Publications

Hyper-Kamiokande consists of two identical water-Cherenkov detectors of total 520 kt, with the first one in Japan at 295 km from the J-PARC neutrino beam with 2.5° off-axis angles (OAAs), and the second one possibly in Korea at a later stage. Having the second detector in Korea would benefit almost all areas of neutrino oscillation physics, mainly due to longer baselines. There are several candidate sites in Korea with baselines of 1000-1300 km and OAAs of 1°-3°. We conducted sensitivity studies on neutrino oscillation physics for a second detector, either in Japan (JD × 2) or Korea (JD + KD), …

Go to article

Defining Freeway Design Capacity Based On Stochastic Observations, Siavash Shojaat, Justin Geistefeldt, Scott A. Parr, Luis Escobar, Brian Wolshon Jun 2018

Defining Freeway Design Capacity Based On Stochastic Observations, Siavash Shojaat, Justin Geistefeldt, Scott A. Parr, Luis Escobar, Brian Wolshon

Faculty Publications

The estimation of capacity as a parameter to assess traffic flow performance on freeway facilities has received considerable attention in the literature. Despite the general acceptance of the stochastic notion of capacity, limited research has been conducted on how to select a single representative design value from a capacity distribution function. This paper reports the results of an empirical comparison between conventional capacity estimates and those obtained by maximizing the sustained flow index (SFI) for 19 U.S. freeway sections. The SFI is defined as the product of the traffic volume and the probability of survival at this volume. The capacity …

Go to article

Using Hydrogen Stable Isotope Ratios To Trace The Geographic Origin Of The Population Of Bactrocera Dorsalis (Diptera: Tephritidae) Trapped In Northern China, Zihua Zhao, Zhenglong Lu, Gadi V.P. Reddy, Shuo Zhao, Guanghui Lin, Jianyun Ding, Jiajiao Wu, Zhihong Li Jun 2018

Using Hydrogen Stable Isotope Ratios To Trace The Geographic Origin Of The Population Of Bactrocera Dorsalis (Diptera: Tephritidae) Trapped In Northern China, Zihua Zhao, Zhenglong Lu, Gadi V.P. Reddy, Shuo Zhao, Guanghui Lin, Jianyun Ding, Jiajiao Wu, Zhihong Li

Faculty Publications

The oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae), is a generalist feeder that is known to successfully feed and breed on a variety of fruits and vegetables in the tropical and subtropical zones of Asia. Recently, the northward extension of B. dorsalis has been reported, and this geographic range increase relates to both climate changes and the rapid development of domestic and international trade and travel. However, it has not been possible to determine the origin of this pest, which is trapped in north China. In this study, traps baited with the sex attractant methyl eugenol were used to …

Go to article

Reflection Negative Kernels And Fractional Brownian Motion, Palle E.T. Jorgensen, Karl Hermann Neeb, Gestur Ólafsson Jun 2018

Reflection Negative Kernels And Fractional Brownian Motion, Palle E.T. Jorgensen, Karl Hermann Neeb, Gestur Ólafsson

Faculty Publications

In this article we study the connection of fractional Brownian motion, representation theory and reflection positivity in quantum physics. We introduce and study reflection positivity for affine isometric actions of a Lie group on a Hilbert space ε and show in particular that fractional Brownian motion for Hurst index 0 < H ≤ 1/2 is reflection positive and leads via reflection positivity to an infinite dimensional Hilbert space if 0 < H < 1/2. We also study projective invariance of fractional Brownian motion and relate this to the complementary series representations of GL2(ℝ). We relate this to a measure preserving action on a Gaussian L2-Hilbert space L2(ε).

Go to article

A Theory Of Minimal K-Types For Flat G-Bundles, Christopher L. Bremer, Daniel S. Sage Jun 2018

A Theory Of Minimal K-Types For Flat G-Bundles, Christopher L. Bremer, Daniel S. Sage

Faculty Publications

The theory of minimal K-types for p-adic reductive groups was developed in part to classify irreducible admissible representations with wild ramification. An important observation was that minimal K-types associated to such representations correspond to fundamental strata. These latter objects are triples (x, r, β), where x is a point in the Bruhat-Tits building of the reductive group G, r is a nonnegative real number, and β is a semistable functional on the degree r associated graded piece of the Moy-Prasad filtration corresponding to x. Recent work on the wild ramification case of the geometric Langlands conjectures suggests that fundamental strata …

Go to article

Stability And Robustness Analysis For A Multispecies Chemostat Model With Delays In The Growth Rates And Uncertainties, Frederic Mazenc, Gonzalo Robledo, Michael Malisoff Jun 2018

Stability And Robustness Analysis For A Multispecies Chemostat Model With Delays In The Growth Rates And Uncertainties, Frederic Mazenc, Gonzalo Robledo, Michael Malisoff

Faculty Publications

We study a chemostat model with an arbitrary number of competing species, one substrate, and constant dilution rates. We allow delays in the growth rates and additive uncertainties. Using constant inputs of certain species, we derive bounds on the sizes of the delays that ensure asymptotic stability of an equilibrium when the uncertainties are zero, which can allow persistence of multiple species. Under delays and uncertainties, we provide bounds on the delays and on the uncertainties that ensure input-to-state stability with respect to uncertainties.

Go to article

A Coupled Ericksen/Allen–Cahn Model For Liquid Crystal Droplets, Angelique Morvant, Ethan Seal, Shawn W. Walker Jun 2018

A Coupled Ericksen/Allen–Cahn Model For Liquid Crystal Droplets, Angelique Morvant, Ethan Seal, Shawn W. Walker

Faculty Publications

We present a model and discretization that couples the Ericksen model of liquid crystals with variable degree of orientation to the Allen–Cahn equations with a mass constraint. The coupled system models liquid crystal droplets with anisotropic surface tension effects due to the liquid crystal molecular alignment. The total energy consists of the Ericksen energy, phase-field (Allen–Cahn) energy, and a weak anchoring energy that couples the liquid crystal to the diffuse interface. We describe our discretization of the total energy along with a method to compute minimizers via a discrete gradient flow algorithm which has a strictly monotone energy decreasing property. …

Go to article

Facially Amphiphilic Polyionene Biocidal Polymers Derived From Lithocholic Acid, Mitra S. Ganewatta, Md Anisur Rahman, Louis Mercado, Tinom Shokfai, Alan W. Decho, Theresa M. Reineke, Chuanbing Tang Jun 2018

Facially Amphiphilic Polyionene Biocidal Polymers Derived From Lithocholic Acid, Mitra S. Ganewatta, Md Anisur Rahman, Louis Mercado, Tinom Shokfai, Alan W. Decho, Theresa M. Reineke, Chuanbing Tang

Faculty Publications

Bacterial infections have become a global issue that requires urgent attention, particularly regarding to emergence of multidrug resistant bacteria. We developed quaternary amine-containing antimicrobial poly(bile acid)s that contain a hydrophobic core of lithocholic acid in the main-chain. Interestingly, by choosing appropriate monomers, these cationic polymers can form core-shell micelles. These polymers exhibited biocidal activity against both Gram-positive and Gram-negative bacterial species. It is demonstrated that the micelles can deliver hydrophobic antibiotics that functionally have dual antimicrobial activities. Cytotoxicity assays against HeLa cells showed dosage-dependent toxicity for polymers with longer linkers.

Go to article

Assessing Relevance Of Tweets For Risk Communication, Xiaohui Liu, Bandana Kar, Chaoyang Zhang, David M. Cochran Jun 2018

Assessing Relevance Of Tweets For Risk Communication, Xiaohui Liu, Bandana Kar, Chaoyang Zhang, David M. Cochran

Faculty Publications

Although Twitter is used for emergency management activities, the relevance of tweets during a hazard event is still open to debate. In this study, six different computational (i.e. Natural Language Processing) and spatiotemporal analytical approaches were implemented to assess the relevance of risk information extracted from tweets obtained during the 2013 Colorado flood event. Primarily, tweets containing information about the flooding events and its impacts were analysed. Examination of the relationships between tweet volume and its content with precipitation amount, damage extent, and official reports revealed that relevant tweets provided information about the event and its impacts rather than any …

Go to article

The Method Of Particular Solutions Using Trigonometric Basis Functions, Zhaolu Tian, Xinxiang Li, C.M. Fan, Ching-Shyang Chen Jun 2018

The Method Of Particular Solutions Using Trigonometric Basis Functions, Zhaolu Tian, Xinxiang Li, C.M. Fan, Ching-Shyang Chen

Faculty Publications

In this paper, the method of particular solutions (MPS) using trigonometric functions as the basis functions is proposed to solve two-dimensional elliptic partial differential equations. The inhomogeneous term of the governing equation is approximated by Fourier series and the closed-form particular solutions of trigonometric functions are derived using the method of undetermined coefficients. Once the particular solutions for the trigonometric basis functions are derived, the standard MPS can be applied for solving partial differential equations. In comparing with the use of radial basis functions and polynomials in the MPS, our proposed approach provides another simple approach to effectively solving two-dimensional …

Go to article

The Effect Of Light Conditions On Interpreting Oil Composition Engineering In Arabidopsis Seeds, Nischal Karki, Philip D. Bates Jun 2018

The Effect Of Light Conditions On Interpreting Oil Composition Engineering In Arabidopsis Seeds, Nischal Karki, Philip D. Bates

Faculty Publications

Arabidopsis thaliana is the most developed and utilized model plant. In particular, it is an excellent model for proof‐of‐concept seed oil engineering studies because it accumulates approximately 37% seed oil by weight, and it is closely related to important Brassicaceae oilseed crops. Arabidopsis can be grown under a wide variety of conditions including continuous light; however, the amount of light is strongly correlated with total seed oil accumulation. In addition, many attempts to engineer novel seed oil fatty acid compositions in Arabidopsis have reported significant reductions in oil accumulation; however, the relative reduction from the nontransgenic controls varies greatly within …

Go to article

Universal Airfoil Parametrization Using B-Splines, Dev Rajnarayan, Andrew Ning, Judd Mehr Jun 2018

Universal Airfoil Parametrization Using B-Splines, Dev Rajnarayan, Andrew Ning, Judd Mehr

Faculty Publications

In this paper, we apply well-known techniques for parametric curves to the definition and deformation of airfoil sections. While it has already been shown that many versions of Kulfan’s Class Shape Transformation (CST) are exactly equivalent to Bézier curves, we show here that all NACA 4-digit thickness distributions and the PARSEC parametrization of Sobiezcky are also higher-order Bézier curves. As with CST, Béziers and B-Splines provide direct control over aerodynamically meaningful features such as nose radius and boat-tail angle, but also provide more a intuitive parametrization of the rest of the airfoil surface. We show the efficacy of B-Spline-based parametrizations …

Go to article

Secure Transmission With Guaranteed User Satisfaction In Heterogeneous Networks: A Two-Level Stackelberg Game Approach, Nanmiao Wu, Xiangwei Zhou, Mingxuan Sun Jun 2018

Secure Transmission With Guaranteed User Satisfaction In Heterogeneous Networks: A Two-Level Stackelberg Game Approach, Nanmiao Wu, Xiangwei Zhou, Mingxuan Sun

Faculty Publications

In this paper, secure transmission in a heterogeneous network in the presence of multiple eavesdroppers is studied. A game-theoretic framework is proposed to enhance the security of the macro base station (MBS), while guaranteeing user satisfaction of the small base stations (SBSs) by exploiting the cooperation and competition among the entire network. Specifically, a two-level Stackelberg game is formulated, where the MBS employs a set of competing jamming SBSs to jam the eavesdroppers at the top level, and each employed jamming SBS may require offloading service from multiple competing helping SBSs in its cluster at the bottom level if needed. …

Go to article

Identifying Prevalent Mathematical Pathways To Engineering In South Carolina, Eliza Gallagher, Christy Brown, D. Andrew Brown, Kristin Kelly Frady, Patrick Bass, Michael A. Matthews, Thomas T. Peters, Robert J. Rabb, Ikhalfani Solan, Ronald W. Welch, Anand K. Gramopadhye Jun 2018

Identifying Prevalent Mathematical Pathways To Engineering In South Carolina, Eliza Gallagher, Christy Brown, D. Andrew Brown, Kristin Kelly Frady, Patrick Bass, Michael A. Matthews, Thomas T. Peters, Robert J. Rabb, Ikhalfani Solan, Ronald W. Welch, Anand K. Gramopadhye

Faculty Publications

National data indicate that initial mathematics course placement in college is a strong predictor of persistence to degree in engineering, with students placed in calculus persisting at nearly twice the rate of those placed below calculus. Within the state of South Carolina, approximately 95% of engineering-intending students who initially place below calculus are from in-state. In order to make systemic change, we are first analyzing system-wide data to identify prevalent educational pathways within the state, and the mathematical milestones along those pathways taken by students in engineering and engineering-related fields. This paper reports preliminary analysis of that data to understand …

Go to article

Contribution Of Hi-Bearing Ultra-Diffuse Galaxies To The Cosmic Number Density Of Galaxies, M. Jones, E. Papastergis, V. Pandya, L. Leisman, Aaron J. Romanowsky, L. Yung, R. Somerville, E. Adams Jun 2018

Contribution Of Hi-Bearing Ultra-Diffuse Galaxies To The Cosmic Number Density Of Galaxies, M. Jones, E. Papastergis, V. Pandya, L. Leisman, Aaron J. Romanowsky, L. Yung, R. Somerville, E. Adams

Faculty Publications

We estimate the cosmic number density of the recently identified class of HI-bearing ultra-diffuse sources (HUDs) based on the completeness limits of the ALFALFA survey. These objects have HI masses approximately in the range 8.5 < logMHI∕M⊙ < 9.5, average r-band surface brightnesses fainter than 24 mag arcsec−2, half-light radii greater than 1.5 kpc, and are separated from neighbours by at least 350 kpc. In this work we demonstrate that they contribute at most ~6% of the population of HI-bearing dwarfs detected by ALFALFA (with similar HI masses), have a total cosmic number density of (1.5 ± 0.6) × 10−3 …

Go to article

The Sluggs Survey: A Comparison Of Total-Mass Profiles Of Early-Type Galaxies From Observations And Cosmological Simulations, To ∼4 Effective Radii, Sabine Bellstedt, Duncan Forbes, Aaron Romanowsky, Rhea-Silvia Remus, Adam Stevens, Jean Brodie, Adriano Poci, Richard Mcdermid, Adebusola Alabi, Leonie Chevalier, Caitlin Adams, Anna Ferré-Mateu, Asher Wasserman, Viraj Pandya Jun 2018

The Sluggs Survey: A Comparison Of Total-Mass Profiles Of Early-Type Galaxies From Observations And Cosmological Simulations, To ∼4 Effective Radii, Sabine Bellstedt, Duncan Forbes, Aaron Romanowsky, Rhea-Silvia Remus, Adam Stevens, Jean Brodie, Adriano Poci, Richard Mcdermid, Adebusola Alabi, Leonie Chevalier, Caitlin Adams, Anna Ferré-Mateu, Asher Wasserman, Viraj Pandya

Faculty Publications

We apply the Jeans Anisotropic Multi-Gaussian Expansion dynamical modelling method to SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey data of early-type galaxies in the stellar mass range 1010 < M*/M⊙ < 1011.6 that cover a large radial range of 0.1–4.0 effective radii. We combine SLUGGS and ATLAS3D data sets to model the total-mass profiles of a sample of 21 fast-rotator galaxies, utilizing a hyperparameter method to combine the two independent data sets. The total-mass density profile slope values derived for these galaxies are consistent with those measured in the inner regions of galaxies by other studies. Furthermore, the total-mass density slopes (γtot) appear to be universal over this broad stellar mass range, with an average value of γtot =  −2.24 ±  0.05 , i.e. slightly steeper than isothermal. We compare our results to model galaxies from the Magneticum and EAGLE cosmological hydrodynamic simulations, in order to probe the mechanisms that are responsible for varying total-mass density profile slopes. The simulated-galaxy slopes are shallower than the observed values by ∼0.3–0.5, indicating that the physical processes shaping the mass distributions of galaxies in cosmological simulations are still incomplete. For galaxies with M* > 1010.7 M⊙ in the Magneticum simulations, we identify a significant anticorrelation between total-mass density profile slopes and the fraction of stellar mass formed ex situ (i.e. accreted), whereas this anticorrelation is weaker for lower stellar masses, implying that the measured total-mass density slopes for low-mass galaxies are less likely to be determined by merger activity.

Go to article

Isotopic Composition Of Sinking Particles: Oil Effects, Recovery And Baselines In The Gulf Of Mexico, 2010-2015, Jeff Chanton, Sarah L.C. Giering, Samantha H. Bosman, Kelsey L. Rogers, Julia Sweet, Vernon Asper, Arne-R. Diercks, Uta Passow May 2018

Isotopic Composition Of Sinking Particles: Oil Effects, Recovery And Baselines In The Gulf Of Mexico, 2010-2015, Jeff Chanton, Sarah L.C. Giering, Samantha H. Bosman, Kelsey L. Rogers, Julia Sweet, Vernon Asper, Arne-R. Diercks, Uta Passow

Faculty Publications

The extensive release of oil during the 2010 Deepwater Horizon spill in the northern Gulf of Mexico perturbed the pelagic ecosystem and associated sinking material. To gauge the recovery and post-spill baseline sources, we measured D14C, d13C and d34S of sinking particles near the spill site and at a reference site and natural seep site. Particulates were collected August 2010–April 2016 in sediment traps moored at sites with depths of 1160–1660 m. Near the spill site, changes in D14C indicated a 3-year recovery period, while d34S indicated 1–2 years, which agreed with estimates of 1–2 years based on hydrocarbon composition. …

Go to article

Fractal Diffusion In High Temperature Polymer Electrolyte Fuel Cell Membranes, Bernhard Hopfenmüller, Reiner Zorn, Olaf Holderer, Oxana Ivanova, Werner Lehnert, Wiebke Lüke, Georg Ehlers, Niina Jalarvo, Gerald J. Schneider, Michael Monkenbusch, Dieter Richter May 2018

Fractal Diffusion In High Temperature Polymer Electrolyte Fuel Cell Membranes, Bernhard Hopfenmüller, Reiner Zorn, Olaf Holderer, Oxana Ivanova, Werner Lehnert, Wiebke Lüke, Georg Ehlers, Niina Jalarvo, Gerald J. Schneider, Michael Monkenbusch, Dieter Richter

Faculty Publications

© 2018 Author(s). The performance of fuel cells depends largely on the proton diffusion in the proton conducting membrane, the core of a fuel cell. High temperature polymer electrolyte fuel cells are based on a polymer membrane swollen with phosphoric acid as the electrolyte, where proton conduction takes place. We studied the proton diffusion in such membranes with neutron scattering techniques which are especially sensitive to the proton contribution. Time of flight spectroscopy and backscattering spectroscopy have been combined to cover a broad dynamic range. In order to selectively observe the diffusion of protons potentially contributing to the ion conductivity, …

Go to article

Nearly Defect-Free Dynamical Models Of Disordered Solids: The Case Of Amorphous Silicon, Raymond Atta-Fynn, Parthapratim Biswas May 2018

Nearly Defect-Free Dynamical Models Of Disordered Solids: The Case Of Amorphous Silicon, Raymond Atta-Fynn, Parthapratim Biswas

Faculty Publications

It is widely accepted in the materials modeling community that defect-free realistic networks of amorphous silicon cannot be prepared by quenching from a molten state of silicon using classical or ab initio molecular-dynamics (MD) simulations. In this work, we address this long-standing problem by producing nearly defect-free ultra-large models of amorphous silicon, consisting of up to half a million atoms, using classical MD simulations. The structural, topological, electronic, and vibrational properties of the models are presented and compared with experimental data. A comparison of the models with those obtained from using the modified Wooten-Winer-Weaire bond-switching algorithm shows that the models …

Go to article

Narrowing The Scope Of Failure Prediction Using Targeted Fault Load Injection, Paul L. Jordan, Gilbert L. Peterson, Alan C. Lin, Michael J. Mendenhall, Andrew J. Sellers May 2018

Narrowing The Scope Of Failure Prediction Using Targeted Fault Load Injection, Paul L. Jordan, Gilbert L. Peterson, Alan C. Lin, Michael J. Mendenhall, Andrew J. Sellers

Faculty Publications

As society becomes more dependent upon computer systems to perform increasingly critical tasks, ensuring that those systems do not fail becomes increasingly important. Many organizations depend heavily on desktop computers for day-to-day operations. Unfortunately, the software that runs on these computers is written by humans and, as such, is still subject to human error and consequent failure. A natural solution is to use statistical machine learning to predict failure. However, since failure is still a relatively rare event, obtaining labelled training data to train these models is not a trivial task. This work presents new simulated fault-inducing loads that extend …

Go to article

Range Information Characterization Of The Hokuyo Ust-20lx Lidar Sensor, Matthew A. Cooper, John F. Raquet, Rick Patton May 2018

Range Information Characterization Of The Hokuyo Ust-20lx Lidar Sensor, Matthew A. Cooper, John F. Raquet, Rick Patton

Faculty Publications

This paper presents a study on the data measurements that the Hokuyo UST-20LX Laser Rangefinder produces, which compiles into an overall characterization of the LiDAR sensor relative to indoor environments. The range measurements, beam divergence, angular resolution, error effect due to some common painted and wooden surfaces, and the error due to target surface orientation are analyzed. It was shown that using a statistical average of sensor measurements provides a more accurate range measurement. It was also shown that the major source of errors for the Hokuyo UST-20LX sensor was caused by something that will be referred to as “mixed …

Go to article

First Prev Next Last