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2013

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Articles 10531 - 10560 of 11462

Full-Text Articles in Physical Sciences and Mathematics

The Graphic Nature Of The Symmetric Group, J.L. Brumbaugh '13, Madeleine Bulkow '14, Luis Alberto Garcia '14, Stephan Ramon Garcia, Matt Michal '15, Andrew P. Turner '14 Jan 2013

The Graphic Nature Of The Symmetric Group, J.L. Brumbaugh '13, Madeleine Bulkow '14, Luis Alberto Garcia '14, Stephan Ramon Garcia, Matt Michal '15, Andrew P. Turner '14

Pomona Faculty Publications and Research

We investigate a remarkable class of exponential sums which are derived from the symmetric groups and which display a diverse array of visually appealing features. Our interest in these expressions stems not only from their astounding visual properties, but also from the fact that they represent a novel and intriguing class of supercharacters.

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Making Common Cause For Conservation: The Pinchot Institute And Grey Towers National Historic Site, 1963-2013, Char Miller Jan 2013

Making Common Cause For Conservation: The Pinchot Institute And Grey Towers National Historic Site, 1963-2013, Char Miller

Pomona Faculty Publications and Research

This year marks the 50th anniversary of the establishment of the Pinchot Institute for Conservation and the donation of the Pinchot family home Grey Towers to the U.S. Forest Service. In the following essay, historian and Pinchot biographer Char Miller discusses how the Institute is applying Gifford Pinchot’s principles to contemporary environmental issues. It is adapted from Seeking the Greatest Good: The Conservation Legacy of Gifford Pinchot, his new history of the Institute, and is published with kind permission of the University of Pittsburgh Press.

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The Brave New World Of Open Access & Creative Commons: A Humanistic Experiment In Mathematical Publishing, Gizem Karaali Jan 2013

The Brave New World Of Open Access & Creative Commons: A Humanistic Experiment In Mathematical Publishing, Gizem Karaali

Pomona Faculty Publications and Research

In January 2011 the Journal of Humanistic Mathematics (JHM) published its first issue. JHM (http://scholarship.claremont.edu/jhm) is an online-only, peer-reviewed, open-access journal which has passed the all-important ten-thousand-download barrier in its first anniversary. In order to remain faithful to the fundamental principles of open access, JHM uses Creative Commons licensing, where authors retain copyright of their work, but others are free to reuse them (with proper attribution). In this note I share and reflect upon our experience with open access and Creative Commons.

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School Choice As A One-Sided Matching Problem: Cardinal Utilities And Optimization, Sinan Aksoy, Alexander Adam Azzam, Chaya Coppersmith, Julie Glass, Gizem Karaali, Xueying Zhao, Xinjing Zhu Jan 2013

School Choice As A One-Sided Matching Problem: Cardinal Utilities And Optimization, Sinan Aksoy, Alexander Adam Azzam, Chaya Coppersmith, Julie Glass, Gizem Karaali, Xueying Zhao, Xinjing Zhu

Pomona Faculty Publications and Research

The school choice problem concerns the design and implementation of matching mechanisms that produce school assignments for students within a given public school district. Previously considered criteria for evaluating proposed mechanisms such as stability, strategyproofness and Pareto efficiency do not always translate into desirable student assignments. In this note, we explore a class of one-sided, cardinal utility maximizing matching mechanisms focused exclusively on student preferences. We adapt a well-known combinatorial optimization technique (the Hungarian algorithm) as the kernel of this class of matching mechanisms. We find that, while such mechanisms can be adapted to meet desirable criteria not met by …

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Selma Karaali And Artemis Karaali, Gizem Karaali Jan 2013

Selma Karaali And Artemis Karaali, Gizem Karaali

Pomona Faculty Publications and Research

A blog about grandmothers in the fields of science, technology, engineering and mathematics.

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Modeling Bedrock Mining Hotspots Within The Ouachita National Forest, Arkansas, Stephanie H. Mehlhope Jan 2013

Modeling Bedrock Mining Hotspots Within The Ouachita National Forest, Arkansas, Stephanie H. Mehlhope

Theses and Dissertations--Geography

This study, concentrating on the Ouachita Mountain Range in western-central Arkansas, extends prior work on treethrows and their influence on soil development in the region by supplying a method of determining hotspots of bedrock mining by treethrow. Binary logistic regression analysis was employed to determine the abiotic and biotic factors that are highly correlated with the rate of bedrock detachment found in uprooted rootwads from three study sites within the Ouachita National Forest. The produced logistic regression models suggest topographic factors, tree specific characteristics, as well as the local geology and soil characteristics all have a significant effect upon the …

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Amalgamation Of Nucleosides And Amino Acids In Antibiotic Biosynthesis, Sandra H. Barnard Jan 2013

Amalgamation Of Nucleosides And Amino Acids In Antibiotic Biosynthesis, Sandra H. Barnard

Theses and Dissertations--Pharmacy

The rapid increase in antibiotic resistance demands the identification of novel antibiotics with novel targets. One potential antibacterial target is the biosynthesis of peptidoglycan cell wall, which is both ubiquitous and necessary for bacterial survival. Both the caprazamycin-related compounds A-90289 and muraminomicin, as well as the capuramycin-related compounds A-503083 and A-102395 are potent inhibitors of the translocase I enzyme, one of the key enzymes required for cell wall biosynthesis. The caprazamycin-related compounds contain a core nonproteinogen b-hydroxy-a-amino acid referred to as 5’-C-glycyluridine (GlyU). Residing within the biosynthetic gene clusters of the aforementioned compounds is a shared open reading …

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Emerging Multi-Proxy Records Of Late Quaternary Palaeoclimate Dynamics In Turkey And The Surrounding Region, Kathleen Nicoll, Ceren Küçükuysal Jan 2013

Emerging Multi-Proxy Records Of Late Quaternary Palaeoclimate Dynamics In Turkey And The Surrounding Region, Kathleen Nicoll, Ceren Küçükuysal

Turkish Journal of Earth Sciences

We present an overview of selected papers published since 2000 that interpret Late Quaternary multi-proxy palaeoclimate records from Turkey and the surrounding region of the Near-Middle East and Mediterranean region. Existing records in Turkey are rather limited in their resolution, and the locations studied thus far reflect a limited spatial and temporal distribution. Because Turkey is a very large country with numerous mountains that affect local weather conditions and create complex feedbacks, it is difficult to correlate trends across the broad landscape, and beyond. Published instrumental records are too short, and most palaeoclimate proxy records, including many lakes studied in …

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A Unified Approach To Speech Enhancement And Voice Activity Detection, Ceyhan Kasap, Mustafa Levent Arslan Jan 2013

A Unified Approach To Speech Enhancement And Voice Activity Detection, Ceyhan Kasap, Mustafa Levent Arslan

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a unified system for voice activity detection (VAD) and speech enhancement is proposed. In the proposed system, there is mutual exchange of information between VAD and speech enhancement blocks. A new and robust VAD algorithm is implemented for the VAD block of the unified system. The newly proposed VAD algorithm uses a periodicity measure and an energy measure obtained from spectral energy distribution and spectral energy difference of the input speech data. For the speech enhancement block, the modified Wiener filtering (MWF) approach is utilized. It has been shown that the utilization of information exchange between the …

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Quantitative Characterization Of Atmospheric Desert Particles Via Multispectral Lidar Method (Uv To Ir), Using Genetic Algorithms And Compared With Chomette\'S Mode, Samir Zeghbib, Samia Bouzid, Abdelhafid Chaabi Jan 2013

Quantitative Characterization Of Atmospheric Desert Particles Via Multispectral Lidar Method (Uv To Ir), Using Genetic Algorithms And Compared With Chomette\'S Mode, Samir Zeghbib, Samia Bouzid, Abdelhafid Chaabi

Turkish Journal of Physics

Size distribution of desert aerosols was measured via LiDAR multi-spectral method using laser wavelengths from UV to mid-IR \lambda = 0.193, 0.694, 1.064, 3.370 and 10.60 \mu m, and applying statistical Markov chains and genetic algorithms. Our results are compared later with the well-known Chomette's desert model.

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Kantowski-Sachs Cosmological Model With Wet Dark Fluid In The General Theory Of Relativity, Arun Ravishankar, Bivudutta Mishra, Pradyumn Kumar Sahoo Jan 2013

Kantowski-Sachs Cosmological Model With Wet Dark Fluid In The General Theory Of Relativity, Arun Ravishankar, Bivudutta Mishra, Pradyumn Kumar Sahoo

Turkish Journal of Physics

The purpose of this study was to investigate the role of wet dark fluid (WDF) in Kantowski-Sachs space-time in the general theory of relativity. In this theory, we solved the field equations for the case where \rho _{WDF}=-2p_{WDF}. Various physical and geometrical properties of the model are also discussed.

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Heavy-Duty Truck Emissions In The South Coast Air Basin Of California, Gary A. Bishop, Brent G. Schuchmann, Donald H. Stedman Jan 2013

Heavy-Duty Truck Emissions In The South Coast Air Basin Of California, Gary A. Bishop, Brent G. Schuchmann, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

California and Federal emissions regulations for 2007 and newer heavy-duty diesel engines require an order of magnitude reduction in particulate matter and oxides of nitrogen spurring the introduction of new aftertreatment systems. Since 2008 four emission measurement campaigns have been conducted at a Port of Los Angeles location and an inland weigh station in the South Coast Air Basin of California. Fuel specific oxides of nitrogen emissions at the Port have decreased 12% since 2010 while infrared opacity (a measure of particulate matter) remained low, showing no diesel particulate filter deterioration. The weigh station truck’s fuel specific oxides of nitrogen …

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Orthogonal Systems In L^2 Spaces Of A Vector Measure, Eduardo Jiménez Fernández Jan 2013

Orthogonal Systems In L^2 Spaces Of A Vector Measure, Eduardo Jiménez Fernández

Turkish Journal of Mathematics

Let m:\Sigma \to X be a Banach space valued countably additive vector measure. In this paper we present a procedure to construct an m-orthogonal system in the space L^2(m) of square integrable functions with respect to m. If the vector measure is constructed from a family of indeterminate scalar measures, it is possible to obtain a family of polynomials that is orthogonal with respect to this vector measure. On the other hand, if the vector measure is fixed, then we can obtain sequences of orthogonal functions using the Kadec-Pelczynski disjointification method.

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Surface Modifications For Gas Chromatography Micro Columns, Daniel Andre Hirtenstein Jan 2013

Surface Modifications For Gas Chromatography Micro Columns, Daniel Andre Hirtenstein

Dissertations, Theses, and Masters Projects

No abstract provided.

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Distribution And Impacts Of Invasive Bivalve Corbicula Fluminea In Tidal Freshwater York River Tributaries, Matthew Ryan Freedman Jan 2013

Distribution And Impacts Of Invasive Bivalve Corbicula Fluminea In Tidal Freshwater York River Tributaries, Matthew Ryan Freedman

Dissertations, Theses, and Masters Projects

The Asian clam, Corbicula fluminea, is one of the most invasive bivalves in the world but there is limited research on its presence in tidal freshwater systems. Despite its introduction into Chesapeake Bay tributaries in the 1970s, the initial colonization and subsequent development of populations of C. fluminea in the Mattaponi and Pamunkey sub-tributaries of the York River, Virginia, is mostly undocumented. This study assessed the spatial distribution and population structure of C. fluminea in tidal freshwater sections of these rivers (~45km) with benthic surveys during summer 2011 – 2012. Benthic grabs (2.4L, 0.023m2) taken at 40 sites in each …

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Conformal Gravity And The Alcubierre Warp Drive Metric, Gabriele U. Varieschi, Zily Burstein Jan 2013

Conformal Gravity And The Alcubierre Warp Drive Metric, Gabriele U. Varieschi, Zily Burstein

Physics Faculty Works

We present an analysis of the classic Alcubierre metric based on conformal gravity, rather than standard general relativity. The main characteristics of the resulting warp drive remain the same as in the original study by Alcubierre, that is, effective superluminal motion is a viable outcome of the metric. We show that for particular choices of the shaping function, the Alcubierre metric in the context of conformal gravity does not violate the weak energy condition, as was the case of the original solution. In particular, the resulting warp drive does not require the use of exotic matter. Therefore, if conformal gravity …

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Self-Completeness And The Generalized Uncertainty Principle, Maximiliano Isi, Jonas Mureika, Piero Nicolini Jan 2013

Self-Completeness And The Generalized Uncertainty Principle, Maximiliano Isi, Jonas Mureika, Piero Nicolini

Physics Faculty Works

The generalized uncertainty principle discloses a self-complete characteristic of gravity, namely the possibility of masking any curvature singularity behind an event horizon as a result of matter compression at the Planck scale. In this paper we extend the above reasoning in order to overcome some current limitations to the framework, including the absence of a consistent metric describing such Planck-scale black holes. We implement a minimum-size black hole in terms of the extremal configuration of a neutral non-rotating metric, which we derived by mimicking the effects of the generalized uncertainty principle via a short scale modified version of Einstein gravity. …

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Twisted Alexander Polynomials Of 2-Bridge Knots, Jim Hoste, Patrick D. Shanahan Jan 2013

Twisted Alexander Polynomials Of 2-Bridge Knots, Jim Hoste, Patrick D. Shanahan

Mathematics, Statistics and Data Science Faculty Works

We investigate the twisted Alexander polynomial of a 2-bridge knot associated to a Fox coloring. For several families of 2-bridge knots, including but not limited to, torus knots and genus-one knots, we derive formulae for these twisted Alexander polynomials. We use these formulae to confirm a conjecture of Hirasawa and Murasugi for these knots.

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Polynomial Knot And Link Invariants From The Virtual Biquandle, Alissa S. Crans, Allison Henrich, Sam Nelson Jan 2013

Polynomial Knot And Link Invariants From The Virtual Biquandle, Alissa S. Crans, Allison Henrich, Sam Nelson

Mathematics, Statistics and Data Science Faculty Works

The Alexander biquandle of a virtual knot or link is a module over a 2-variable Laurent polynomial ring which is an invariant of virtual knots and links. The elementary ideals of this module are then invariants of virtual isotopy which determine both the generalized Alexander polynomial (also known as the Sawollek polynomial) for virtual knots and the classical Alexander polynomial for classical knots. For a fixed monomial ordering <, the Gr\"obner bases for these ideals are computable, comparable invariants which fully determine the elementary ideals and which generalize and unify the classical and generalized Alexander polynomials. We provide examples to illustrate the usefulness of these invariants and propose questions for future work.

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Torsion In One-Term Distributive Homology, Alissa S. Crans, Józef H. Przytycki, Krzysztof K. Putyra Jan 2013

Torsion In One-Term Distributive Homology, Alissa S. Crans, Józef H. Przytycki, Krzysztof K. Putyra

Mathematics, Statistics and Data Science Faculty Works

The one-term distributive homology was introduced by J.H.Przytycki as an atomic replacement of rack and quandle homology, which was first introduced and developed by R.Fenn, C.Rourke and B.Sanderson, and J.S.Carter, S.Kamada and M.Saito. This homology was initially suspected to be torsion-free, but we show in this paper that the one-term homology of a finite spindle can have torsion. We carefully analyze spindles of block decomposition of type (n,1) and introduce various techniques to compute their homology precisely. In addition, we show that any finite group can appear as the torsion subgroup of the first homology of some finite spindle. Finally, …

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Cohomology Of Frobenius Algebras And The Yang-Baxter Equation, J. Scott Carter, Alissa S. Crans, Mohamed Elhamdadi, Enver Karadayi, Masahico Saito Jan 2013

Cohomology Of Frobenius Algebras And The Yang-Baxter Equation, J. Scott Carter, Alissa S. Crans, Mohamed Elhamdadi, Enver Karadayi, Masahico Saito

Mathematics, Statistics and Data Science Faculty Works

A cohomology theory for multiplications and comultiplications of Frobenius algebras is developed in low dimensions in analogy with Hochschild cohomology of bialgebras based on deformation theory. Concrete computations are provided for key examples. Skein theoretic constructions give rise to solutions to the Yang-Baxter equation using multiplications and comultiplications of Frobenius algebras, and 2-cocycles are used to obtain deformations of R-matrices thus obtained.

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An Adaptive Total Variation Algorithm For Computing The Balanced Cut Of A Graph, Xavier Bresson, Thomas Laurent, David Uminsky, James H. Von Brecht Jan 2013

An Adaptive Total Variation Algorithm For Computing The Balanced Cut Of A Graph, Xavier Bresson, Thomas Laurent, David Uminsky, James H. Von Brecht

Mathematics, Statistics and Data Science Faculty Works

We propose an adaptive version of the total variation algorithm proposed in [3] for computing the balanced cut of a graph. The algorithm from [3] used a sequence of inner total variation minimizations to guarantee descent of the balanced cut energy as well as convergence of the algorithm. In practice the total variation minimization step is never solved exactly. Instead, an accuracy parameter is specified and the total variation minimization terminates once this level of accuracy is reached. The choice of this parameter can vastly impact both the computational time of the overall algorithm as well as the accuracy of …

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A Method Based On Total Variation For Network Modularity Optimization Using The Mbo Scheme, Huiyi Hu, Thomas Laurent, Mason A. Porter, Andrea L. Bertozzi Jan 2013

A Method Based On Total Variation For Network Modularity Optimization Using The Mbo Scheme, Huiyi Hu, Thomas Laurent, Mason A. Porter, Andrea L. Bertozzi

Mathematics, Statistics and Data Science Faculty Works

The study of network structure is pervasive in sociology, biology, computer science, and many other disciplines. One of the most important areas of network science is the algorithmic detection of cohesive groups of nodes called “communities.” One popular approach to finding communities is to maximize a quality function known as modularity to achieve some sort of optimal clustering of nodes. In this paper, we interpret the modularity function from a novel perspective: we reformulate modularity optimization as a minimization problem of an energy functional that consists of a total variation term and an $\ell_2$ balance term. By employing numerical techniques …

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Yeast Eif4b Binds To The Head Of The 40s Ribosomal Subunit And Promotes Mrna Recruitment Through Its N-Terminal And Internal Repeat Domains, Sarah F. Mitchell Jan 2013

Yeast Eif4b Binds To The Head Of The 40s Ribosomal Subunit And Promotes Mrna Recruitment Through Its N-Terminal And Internal Repeat Domains, Sarah F. Mitchell

Chemistry and Biochemistry Faculty Works

Eukaryotic translation initiation factor (eIF)4B stimulates recruitment of mRNA to the 43S ribosomal pre-initiation complex (PIC). Yeast eIF4B (yeIF4B), shown previously to bind single-stranded (ss) RNA, consists of an N-terminal domain (NTD), predicted to be unstructured in solution; an RNA-recognition motif (RRM); an unusual domain comprised of seven imperfect repeats of 26 amino acids; and a C-terminal domain. Although the mechanism of yeIF4B action has remained obscure, most models have suggested central roles for its RRM and ssRNA-binding activity. We have dissected the functions of yeIF4B's domains and show that the RRM and its ssRNA-binding activity are dispensable in vitro …

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Hiv-1 Frameshift Efficiency Is Primarily Determined By The Stability Of Base Pairs Positioned At The Mrna Entrance Channel Of The Ribosome, Kathryn Mouzakis Jan 2013

Hiv-1 Frameshift Efficiency Is Primarily Determined By The Stability Of Base Pairs Positioned At The Mrna Entrance Channel Of The Ribosome, Kathryn Mouzakis

Chemistry and Biochemistry Faculty Works

The human immunodeficiency virus (HIV) requires a programmed -1 ribosomal frameshift for Pol gene expression. The HIV frameshift site consists of a heptanucleotide slippery sequence (UUUUUUA) followed by a spacer region and a downstream RNA stem-loop structure. Here we investigate the role of the RNA structure in promoting the -1 frameshift. The stem-loop was systematically altered to decouple the contributions of local and overall thermodynamic stability towards frameshift efficiency. No correlation between overall stability and frameshift efficiency is observed. In contrast, there is a strong correlation between frameshift efficiency and the local thermodynamic stability of the first 3-4 bp in …

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Counting Links And Knots In Complete Graphs, Loren Abrams, Blake Mellor, Lowell Trott Jan 2013

Counting Links And Knots In Complete Graphs, Loren Abrams, Blake Mellor, Lowell Trott

Mathematics, Statistics and Data Science Faculty Works

We investigate the minimal number of links and knots in embeddings of complete partite graphs in S3. We provide exact values or bounds on the minimal number of links for all complete partite graphs with all but 4 vertices in one partition, or with 9 vertices in total. In particular, we find that the minimal number of links in an embedding of K4,4,1 is 74. We also provide exact values or bounds on the minimal number of knots for all complete partite graphs with 8 vertices.

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Congruence Classes Of 2-Adic Valuations Of Stirling Numbers Of The Second Kind, Curtis Bennett, Edward Mosteig Jan 2013

Congruence Classes Of 2-Adic Valuations Of Stirling Numbers Of The Second Kind, Curtis Bennett, Edward Mosteig

Mathematics, Statistics and Data Science Faculty Works

We analyze congruence classes of S(n,k), the Stirling numbers of the second kind, modulo powers of 2. This analysis provides insight into a conjecture posed by Amdeberhan, Manna and Moll, which those authors established for k at most 5. We provide a framework that can be used to justify the conjecture by computational means, which we then complete for values of k between 5 and 20.

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Security Risks And Protection In Online Learning: A Survey, Yong Chen, Wu He Jan 2013

Security Risks And Protection In Online Learning: A Survey, Yong Chen, Wu He

Distance Learning Faculty & Staff Publications

This paper describes a survey of online learning which attempts to determine online learning providers' awareness of potential security risks and the protection measures that will diminish them. The authors use a combination of two methods: blog mining and a traditional literature search. The findings indicate that, while scholars have identified diverse security risks and have proposed solutions to mitigate the security threats in online learning, bloggers have not discussed security in online learning with great frequency. The differences shown in the survey results generated by the two different methods confirm that online learning providers and practitioners have not considered …

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Dinitrogen Fixation In Aphotic Oxygenated Marine Environments, Eyal Rahav, Edo Bar-Zeev, Sarah Ohayon, Hila Elifantz, Natalia Belkin, Barak Herut, Margaret R. Mulholland, Iiana Berman-Frank Jan 2013

Dinitrogen Fixation In Aphotic Oxygenated Marine Environments, Eyal Rahav, Edo Bar-Zeev, Sarah Ohayon, Hila Elifantz, Natalia Belkin, Barak Herut, Margaret R. Mulholland, Iiana Berman-Frank

OES Faculty Publications

We measured N2 fixation rates from oceanic zones that have traditionally been ignored as sources of biological N2fixation; the aphotic, fully oxygenated, nitrate (NO¯3)-rich, waters of the oligotrophic Levantine Basin (LB) and the Gulf of Aqaba (GA). N2 fixation rates measured from pelagic aphotic waters to depths up to 720 m, during the mixed and stratified periods, ranged from 0.01 nmol N L-1 d-1 to 0.38 nmol N L-1 d-1. N2 fixation rates correlated significantly with bacterial productivity and heterotrophic diazotrophs were identified from aphotic as well as …

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Seasonal Dynamics Of Mesodinium Rubrum In Chesapeake Bay, Matthew D. Johnson, Doane K. Stoecker, Harold G. Marshall Jan 2013

Seasonal Dynamics Of Mesodinium Rubrum In Chesapeake Bay, Matthew D. Johnson, Doane K. Stoecker, Harold G. Marshall

Biological Sciences Faculty Publications

The photosynthetic ciliate Mesodinium rubrum is a common member of coastal phytoplankton communities that is well adapted to low-light, turbid ecosystems. It supports the growth of, or competes with, harmful dinoflagellate species for cryptophyte prey, as well as being a trophic link to copepods and larval fish. We have compiled data from various sources (n = 1063), on the abundance and distribution of M. rubrum in Chesapeake Bay and its tributaries. Because M. rubrum relies on obtaining organelles from cryptophyte algae to maintain rapid growth, we also enumerated cryptophyte algae in the portion of these samples that we collected …

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