Physical Sciences and Mathematics Commons^™

Sub-Planckian Black Holes And The Generalized Uncertainty Principle, Bernard Carr, Jonas R. Mureika, Piero Nicolini

Jonas Mureika

The Black Hole Uncertainty Principle correspondence suggests that there could exist black holes with mass beneath the Planck scale but radius of order the Compton scale rather than Schwarzschild scale. We present a modified, self-dual Schwarzschild-like metric that reproduces desirable aspects of a variety of disparate models in the sub-Planckian limit, while remaining Schwarzschild in the large mass limit. The self-dual nature of this solution under M ↔ M−1 naturally implies a Generalized Uncertainty Principle with the linear form Δx∼1/Δp+Δp. We also demonstrate a natural dimensional reduction feature, in that the gravitational radius and thermodynamics of sub-Planckian objects resemble that …

Aspects Of Noncommutative (1+1)-Dimensional Black Holes, Jonas R. Mureika, Piero Nicolini

Jonas Mureika

We present a comprehensive analysis of the spacetime structure and thermodynamics of ( 1 + 1 )-dimensional black holes in a noncommutative framework. It is shown that a wider variety of solutions are possible than the commutative case considered previously in the literature. As expected, the introduction of a minimal length √ θ cures singularity pathologies that plague the standard two-dimensional general relativistic case, where the latter solution is recovered at large length scales. Depending on the choice of input parameters (black hole mass M, cosmological constant Λ , etc.), black hole solutions with zero, up to six, horizons are …

Fractal Dimensions In Perceptual Color Space: A Comparison Study Using Jackson Pollock’S Art, Jonas R. Mureika

Jonas Mureika

The fractal dimensions of color-specific paint patterns in various Jackson Pollock paintings are calculated using a filtering process that models perceptual response to color differences (L*a*b* color space). The advantage of the L*a*b* space filtering method over traditional red-green-blue (RGB) spaces is that the former is a perceptually uniform (metric) space, leading to a more consistent definition of “perceptually different” colors. It is determined that the RGB filtering method underestimates the perceived fractal dimension of lighter-colored patterns but not of darker ones, if the same selection criteria is applied to each. Implications of the findings to Fechner’s “principle of …

Constraints On Vector Unparticle Physics From Cosmic Censorship, Jonas R. Mureika

Jonas Mureika

Vector unparticle couplings to standard model fields produce repulsive corrections to gravity. From a general relativistic perspective, this leads to an effective Reissner-Nordstrom-like metric whose "charge" is a function of the unparticle coupling constant λ, and therefore can admit naked singularities. Requiring the system to respect cosmic censorship provides a new method of constraining the value of λ. These limits are extremely loose for stellar-mass black holes, but commensurate with existing bounds for primordial black holes. In the case of theoretical low-mass black holes, the bounds on λ are much stricter than those derived from astrophysical and accelerator phenomenology. Additional …

(1+1)-Dimensional Entropic Gravity, R. B. Mann, Jonas R. Mureika

Jonas Mureika

We consider the formulation of entropic gravity in two spacetime dimensions. The usual gravitational force law is derived even in the absence of area, as normally required by the holographic principle. A special feature of this perspective concerns the nature of temperature and entropy defined at a point. We argue that the constancy of the gravitational force in one spatial dimension implies the information contained at each point in space is an internal degree of freedom on the manifold, and furthermore is a universal constant, contrary to previous assertions that entropic gravity in one spatial dimension is ill-defined. We give …

Detecting Vanishing Dimensions Via Primordial Gravitational Wave Astronomy, Jonas R. Mureika, Dejan Stojkovic

Jonas Mureika

Lower dimensionality at higher energies has manifold theoretical advantages as recently pointed out by Anchordoqui et al. [arXiv:1003.5914]. Moreover, it appears that experimental evidence may already exist for it: A statistically significant planar alignment of events with energies higher than TeV has been observed in some earlier cosmic ray experiments. We propose a robust and independent test for this new paradigm. Since ( 2 + 1 )-dimensional spacetimes have no gravitational degrees of freedom, gravity waves cannot be produced in that epoch. This places a universal maximum frequency at which primordial waves can propagate, marked by the transition between dimensions. …

Could Any Black Holes Be Produced At The Lhc?, Jonas R. Mureika, Piero Nicolini, Euro Spallucci

Jonas Mureika

We introduce analytical quantum gravity modifications of the production cross section for terascale black holes by employing an effective ultraviolet cut off l. We find the new cross sections approach the usual "black disk" form at high energy, while they differ significantly near the fundamental scale from the standard increase with respect to s. We show that the heretofore discontinuous step function used to represent the cross section threshold can realistically be modeled by two functions representing the incoming and final parton states in a high energy collision. The growth of the cross section with collision energy is …

Changes In Severe Thunderstorm Environment Frequency During The 21st Century Caused By Anthropogenically Enhanced Global Radiative Forcing, Robert J. Trapp, Noah S. Diffenbaugh, Harold E. Brooks, Michael E. Baldwin, Eric D. Robinson, Jeremy S. Pal

Jeremy Pal

Severe thunderstorms comprise an extreme class of deep convective clouds and produce high-impact weather such as destructive surface winds, hail, and tornadoes. This study addresses the question of how severe thunderstorm frequency in the United States might change because of enhanced global radiative forcing associated with elevated greenhouse gas concentrations. We use global climate models and a high-resolution regional climate model to examine the larger-scale (or “environmental”) meteorological conditions that foster severe thunderstorm formation. Across this model suite, we find a net increase during the late 21st century in the number of days in which these severe thunderstorm environmental conditions …

Consistency Of Projected Drought Over The Sahel With Changes In The Monsoon Circulation And Extremes In A Regional Climate Model Projections, M. B. Sylla, A. T. Gaye, G. S. Jenkins, Jeremy S. Pal, F. Giorgi

Jeremy Pal

As a step toward an increased understanding of climate change over West Africa, in this paper we analyze the relationship between rainfall changes and monsoon dynamics in high-resolution regional climate model experiments performed using the Regional Climate Model (RegCM3). Multidecadal simulations are carried out for present-day and future climate conditions under increased greenhouse gas forcing driven by the global climate model European Center/Hamburg 5 (ECHAM5). Compared to the present day, the future scenario simulation produces drier conditions over the Sahel and wetter conditions over orographic areas. The Sahel drying is accompanied by a weaker monsoon flow, a southward migration and …

Regional Climate Modeling For The Developing World: The Ictp Regcm3 And Regcnet, Jeremy S. Pal, Filippo Giorgi, Xunqiang Bi, Nellie Elguindi, Fabien Solmon, Xuejie Gao, Sara A. Rauscher, Raquel Francisco, Ashraf Zakey, Jonathan Winter, Moetasim Ashfaq, Faisal S. Syed, Jason L. Bell, Noah S. Diffenbaugh, Jagadish Karmacharya, Abourahamane Konaré, Daniel Martinez, Rosmeri P. Da Rocha, Lisa C. Sloan, Allison L. Steiner

Jeremy Pal

Regional climate models are important research tools available to scientists around the world, including in economically developing nations (EDNs). The Earth Systems Physics (ESP) group of the Abdus Salam International Centre for Theoretical Physics (ICTP) maintains and distributes a state-of-the-science regional climate model called the ICTP Regional Climate Model version 3 (RegCM3), which is currently being used by a large research community for a diverse range of climate-related studies. The RegCM3 is the central, but not only, tool of the ICTP-maintained Regional Climate Research Network (RegCNET) aimed at creating south–south and north–south scientific interactions on the topic of climate and …

History Of Computing, George K. Thiruvathukal, David B. Dennis

George K. Thiruvathukal

The social and organizational history of humanity is intricately entangled with the history of technology in general and the technology of information in particular. Advances in this area have often been closely involved in social and political transformations. While the contemporary period is often referred to by such names as the Computing and Information Age, this is the culmination of a series of historical transformations that have been centuries in the making. This course will provide a venue for students to learn about history through the evolution of number systems and arithmetic, calculating and computing machines, and advanced communication technology …

The Feferman-Vaught Theorem, Mostafa Mirabi

Mostafa Mirabi

Improved Protein Structure Reconstruction Using Secondary Structures, Contacts At Higher Distance Thresholds, And Non-Contacts, Badri Adhikari, Jianlin Cheng

Badri Adhikari

Cobalt-Doped Ceria/Reduced Graphene Oxide Nanocomposite As An Efficient Oxygen Reduction Reaction Catalyst And Supercapacitor Material, Shaikh Parwaiz, Kousik Bhunia, Ashok Kumar Das, Mohammad Mansoob Khan Dr, Debabrata Pradhan

Dr. Mohammad Mansoob Khan

"Blinded By The Lines: Mid-Ir Spectra Of Mira Variables Taken With Spitzer", Dana Baylis-Aguirre, Michelle J. Creech-Eakman, Donald G. Luttermoser, Tina Gueth

Donald G. Luttermoser

We present preliminary analysis of mid-infrared spectra of M-type and C-type Mira variables. Due to the brightness of this sample, it is straightforward to monitor changes with phase in the infrared spectral features of these regular pulsators. We have spectra of 25 Mira variables, taken with phase, using the Spitzer Infrared Spectrograph (IRS) high-resolution module. Each star has multiple spectra obtained over a one-year period from 2008-09. This is a rich, unique data set due to multiple observations of each star and the high signal-to-noise ratio from quick exposure times to prevent saturation of the IRS instrument. This paper focuses …

Ionic Liquid Extraction Unveils Previously Occluded Humic-Bound Iron In Peat Soil Pore Water, Timothy J. Veverica, Evan S. Kane, Amy Marcarelli, Sarah A. Green

Amy Marcarelli

Globally, peatland ecosystems store tremendous amounts of C relative to their extent on the landscape, largely owing to saturated soils which limit decomposition. While there is still considerable uncertainty regarding CO2 production potential below the water table in peatland ecosystems, extracellular Fe reduction has been suggested as a dominant pathway for anaerobic metabolism. However, colorimetric methods commonly used to quantitate Fe and partition between redox species are known to be unreliable in the presence of complex humic substances, which are common in peatland pore water. We evaluated both the standard o-phenanthroline (o-P) Method and an ionic liquid extraction (ILE) Method …

Grnsight: A Web Application And Service For Visualizing Models Of Small- To Medium-Scale Gene Regulatory Networks, Kam D. Dahlquist, John David N. Dionisio, Ben G. Fitzpatrick, Nicole A. Anguiano, Anindita Varshneya, Britain J. Southwick, Mihir Samdarshi

Ben G. Fitzpatrick

GRNsight is a web application and service for visualizing models of gene regulatory networks (GRNs). A gene regulatory network (GRN) consists of genes, transcription factors, and the regulatory connections between them which govern the level of expression of mRNA and protein from genes. The original motivation came from our efforts to perform parameter estimation and forward simulation of the dynamics of a differential equations model of a small GRN with 21 nodes and 31 edges. We wanted a quick and easy way to visualize the weight parameters from the model which represent the direction and magnitude of the influence of …

Ecosystem Modeling Of College Drinking: Parameter Estimation And Comparing Models To Data, Azmy S. Ackleh, Ben G. Fitzpatrick, Richard Scribner, Neal Simonsen, Jeremy J. Thibodeaux

Ben G. Fitzpatrick

Recently we developed a model composed of five impulsive differential equations that describes the changes in drinking patterns (that persist at epidemic level) amongst college students. Many of the model parameters cannot be measured directly from data; thus, an inverse problem approach, which chooses the set of parameters that results in the “best” model to data fit, is crucial for using this model as a predictive tool. The purpose of this paper is to present the procedure and results of an unconventional approach to parameter estimation that we developed after more common approaches were unsuccessful for our specific problem. The …

Optimization And Control Of Agent-Based Models In Biology: A Perspective, G. An, B. G. Fitzpatrick, S. Christley, P. Federico, A. Kanarek, R. Miller Neilan, M. Oremland, R. Salinas, R. Laubeanbacher, S. Lenhart

Ben G. Fitzpatrick

Agent-based models (ABMs) have become an increasingly important mode of inquiry for the life sciences. They are particularly valuable for systems that are not understood well enough to build an equation-based model. These advantages, however, are counterbalanced by the difficulty of analyzing and using ABMs, due to the lack of the type of mathematical tools available for more traditional models, which leaves simulation as the primary approach. As models become large, simulation becomes challenging. This paper proposes a novel approach to two mathematical aspects of ABMs, optimization and control, and it presents a few first steps outlining how one might …

Robustness, Weak Stability, And Stability In Distribution Of Adaptive Filteringalgorithms Under Model Mismatch, Ben G. Fitzpatrick, G. Yin, Le Yi Wang

Ben G. Fitzpatrick

This work is concerned with robustness, convergence, and stability of adaptive filtering (AF) type algorithms in the presence of model mismatch. The algorithms under consideration are recursive and have inherent multiscale structure. They can be considered as dynamic systems, in which the `state' changes much more slowly than the perturbing noise. Beyond the existing results on adaptive algorithms, model mismatch significantly affects convergence properties of AF algorithms, raising issues of algorithm robustness. Weak convergence and weak stability (i.e., recurrence) under model mismatch are derived. Based on the limiting stochastic differential equations of suitably scaled iterates, stability in distribution is established. …

Biophysical And Computational Studies Of The Vcci:Vmip-Ii Complex, Anna Nguyen, Nai-Wei Kuo, Laura Showalter, Ricardo Ramos, Cynthia Dupureur, Michael Colvin, Patricia Liwang

Cynthia Dupureur

Physical Mechanisms Leading To The Coulomb Blockade And Coulomb Staircase Structures In Strongly Coupled Multi-Island Single-Electron Devices, Madhusudan A. Savaikar, Paul L. Bergstrom, John A. Jaszczak

Paul Bergstrom

Controlled transport of electrons through tunnel junctions and their confinement by mesoscopic structures have opened up immense possibilities of single-electron device (SED) applications. The realization of a practical working SED has remained challenging largely owing to the poor understanding of the physics of operation of singe-electron tunneling devices, especially of those with multiple nanometer-sized islands. In this simulation study of one-dimensional (1D) multi-island chains, we propose physical mechanisms that lead to the coulomb blockade (CB) and coulomb staircase (CS) characteristics that are enhanced by the geometrical disorder in the chain. With increasing source-drain (VDS = VD − VS) bias, a …

New Flexible Channels For Room Temperature Tunneling Field Effect Transistors, Boyi Hao, Anjana Asthana, Paniz Khanmohammadi, Paul Bergstrom, Douglas R. Banyai, Madhusudan A. Savaikar, John A. Jaszczak, Yoke Khin Yap

Paul Bergstrom

Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under various …

Simulation Of Charge Transport In Multi-Island Tunneling Devices: Application To Disordered One-Dimensional Systems At Low And High Biases, Madhusudan A. Savaikar, Douglas R. Banyai, Paul Bergstrom, John A. Jaszczak

Paul Bergstrom

Although devices have been fabricated displaying interesting single-electron transport characteristics, there has been limited progress in the development of tools that can simulate such devices based on their physical geometry over a range of bias conditions up to a few volts per junction. In this work, we present the development of a multi-island transport simulator, MITS, a simulator of tunneling transport in multi-island devices that takes into account geometrical and material parameters, and can span low and high source-drain biases. First, the capabilities of MITS are demonstrated by modeling experimentaldevices described in the literature, and showing that the simulated device …

Micro Dh: Digital Humanities At The Small Scale, Roopika Risam, Susan Edwards

Roopika Risam

Time Varying Parameter Estimation Scheme For A Linear Stochastic Differential Equation.Pdf, Michael Otunuga

Olusegun Michael Otunuga

Evaluation Of Commercial Nickel–Phosphorus Coating For Ultracold Neutron Guides Using A Pinhole Bottling Method, Robert W. Pattie, Evan R. Adamek, T. Brenner, A. Brandt, Leah J. Broussard, Nathan Callahan, Stephen M. Clayton, Chris Cude-Woods, Scott A. Currie, Peter Geltenbort, Takeyasu M. Ito, T. Lauer, Chenyu Liu, Jaroslaw Majewski, Mark F. Makela, Yasuhiro Masuda, Christopher L. Morris, John C. Ramsey, Daniel J. Salvat, Alexander Saunders, Juri Schroffenegger, Zebo Tang, Wanchun Wei, Zhehui Wang, Erik B. Watkins, Albert R. Young, B.A. Zeck

Robert W. Pattie Jr.

Effects Of Anthropomorphism On Trust In Human-Robot Interaction, Keith R. Macarthur, William T. Shugars, Tracy L. Sanders, Peter A. Hancock

Keith Reid MacArthur

Modelling And Hazard Analysis For Contaminated Sediments Using Stamp Model, Karim Hardy, Franck Guarnieri

Karim Hardy

Processes for remediation (removal of pollution or contaminants) of contaminated sediments have been very efficient. These technologies, which are particularly complex, call for a comprehensive approach to risk analysis which characterises all threats (to humans, equipment, local residents, the environment, etc.) . The STAMP accident model (Systems-Theoretic Accident Model and Processes) is an example of such a comprehensive approach, and it has been chosen to characterise the risks associated with Novosol (registered trademark), an innovative remediation process.

Modelling And Hazard Analysis For Contaminated Sediments Using Stamp Model And Stpa Tool, Karim Hardy, Franck Guarnieri

Karim Hardy

The goal of this article is dual: first, introducing a new model of accident named STAMP (systems-theoretic accident modeling and processes); then applying the model to an innovative process for the treatment of contaminated substances and the re-use of treated substances. This article is a demonstration for a need of a new tool to take into account hazards and safety within socio-technical systems.