Physical Sciences and Mathematics Commons^™

Dipolar Ordering In Crystals Of Mn12 Ac, Dmitry A. Garanin

Publications and Research

Ordering in realistic elongated box-shape crystals of the molecular magnet Mn_12 Ac is investigated with the site-resolved mean-field approximation that does not assume a uniform ordering. It is shown that ferromagnetic ordering should not occur in crystals with the aspect ratio up to 12. Instead, for the aspect ratio about 6, the inner and outer regions of the crystal order in different directions, uniformly along its length. Finding ordering temperature by extrapolating the inverse susceptibility curve does not provide a correct T_C.

Edges And Diffractive Effects In Casimir Energies, Daniel N. Kabat, Dimitra Karabali, V P. Nair

Publications and Research

The prototypical Casimir effect arises when a scalar field is confined between parallel Dirichlet boundaries. We study corrections to this when the boundaries themselves have apertures and edges. We consider several geometries: a single plate with a slit in it, perpendicular plates separated by a gap, and two parallel plates, one of which has a long slit of large width, related to the case of one plate being semi-infinite. We develop a general formalism for studying such problems, based on the wavefunctional for the field in the gap between the plates. This formalism leads to a lower dimensional theory defined …

On The Casimir Interaction Between Holes In A Plate, Daniel N. Kabat, Dimitra Karabali, V P. Nair

Publications and Research

We study the leading long-distance attractive force between two holes in a plate arising from a scalar eld with Dirichlet boundary conditions on the plate. We use a formalism in which the interaction is governed by a non-local eld theory which lives on the two holes. The interaction energy is proportional to Q1Q2=r7 at large separation r, where Q1 and Q2 are certain charges associated with the holes. We compute these charges for round and rectangular holes. We show that the 1=r7 behavior is universal for separations large compared to the linear dimensions of the holes, irrespective of the spin …

Dynamical Decompactification And Three Large Dimensions, Brian Greene, Daniel N. Kabat, Stefanos Marnerides

Publications and Research

We study string gas dynamics in the early universe and seek to realize the Brandenberger - Vafa mechanism - a goal that has eluded earlier works - that singles out three or fewer spatial dimensions as the number which grow large cosmologically. Considering wound string interactions in an impact parameter picture, we show that a strong exponential suppression in the interaction rates for d > 3 spatial dimensions reflects the classical argument that string worldsheets generically intersect in at most four spacetime dimensions. This description is appropriate in the early universe if wound strings are heavy - wrapping long cycles - …

The Hamiltonian Approach To Yang-Mills (2 + 1): Expansion Scheme And Corrections To String Tension, Dimitra Karabali, V P. Nair, Alexandr Yelinkov

Publications and Research

We carry out further analysis of the Hamiltonian approach to Yang-Mills theory in 2+1 dimensions which helps to place the calculation of the vacuum wave function and the string tension in the context of a systematic expansion scheme. The solution of the Schrodinger equation is carried out recursively. The computation of correlators is re-expressed in terms of a two-dimensional chiral boson theory. The effective action for this theory is calculated to first order in our expansion scheme and to the fourth order in a kinematic expansion parameter. The resulting corrections to the string tension are shown to be very small, …

A Multivalent Dna Aptamer Specific For The B-Cell Receptor On Human Lymphoma And Leukemia, Prabodhika R. Mallikaratchy, Alessandro Ruggiero, Jeffrey R. Gardner, Vitaly Kuryavyi, William F. Maguire, Mark L. Heaney, Michael R. Mcdevitt, Dinshaw J. Patel, David A. Scheinberg

Publications and Research

Long-term survival still eludes most patients with leukemia and non-Hodgkin’s lymphoma. No approved therapies target the hallmark of the B cell, its mIgM, also known as the B-cell receptor (BCR). Aptamers are small oligonucleotides that can specifically bind to a wide range of target molecules and offer some advantages over antibodies as therapeutic agents. Here, we report the rational engineering of aptamer TD05 into multimeric forms reactive with the BCR that may be useful in biomedical applications. Systematic truncation of TD05 coupled with modification with locked nucleic acids (LNA) increased conformational stability and nuclease resistance. Trimeric and tetrameric versions with …

Core/Shell Nanoparticles As Hybrid Platforms For The Fabrication Of A Hydrogen Peroxide Biosensor, Yu-Ho Won, Doreen Aboagye, Ho Seong Jang, Andrei Jitianu, Lia A. Stanciu

Publications and Research

No abstract provided.

Nearest Neighbor Search With Strong Location Privacy, Stavros Papadopoulos, Spiridon Bakiras, Dimitris Papadias

Publications and Research

The tremendous growth of the Internet has significantly reduced the cost of obtaining and sharing information about individuals, raising many concerns about user privacy. Spatial queries pose an additional threat to privacy because the location of a query may be sufficient to reveal sensitive information about the querier. In this paper we focus on k nearest neighbor (kNN) queries and define the notion of strong location privacy, which renders a query indistinguishable from any location in the data space. We argue that previous work fails to support this property for arbitrary kNN search. Towards this end, we introduce methods that …

Optimal Cryptographic Hardness Of Learning Monotone Functions, Dana Dachman-Soled, Homin K. Lee, Tal Malkin, Rocco A. Servedio, Andrew Wan, Hoeteck Wee

Publications and Research

Over the years a range of positive algorithmic results have been obtained for learning various classes of monotone Boolean functions from uniformly distributed random examples. Prior to our work, however, the only negative result for learning monotone functions in this model has been an information-theoretic lower bound showing that certain super-polynomial-size monotone circuits cannot be learned to accuracy 1/2+w(log n/ p n) (Blum, Burch, and Langford, FOCS’98). This is in contrast with the situation for nonmonotone functions, where a wide range of cryptographic hardness results establish that various “simple” classes of polynomial-size circuits are not learnable by polynomial-time algorithms.

In …

Correlating Molecular Phylogeny With Venom Apparatus Occurrence In Panamic Auger Snails (Terebridae), Mandë Holford, Nicolas Puillandre, Maria Vittoria Modica, Maren Watkins, Rachel Collin, Eldredge Bermingham, Baldomero M. Olivera

Publications and Research

Central to the discovery of neuroactive compounds produced by predatory marine snails of the superfamily Conoidea (cone snails, terebrids, and turrids) is identifying those species with a venom apparatus. Previous analyses of western Pacific terebrid specimens has shown that some Terebridae groups have secondarily lost their venom apparatus. In order to efficiently characterize terebrid toxins, it is essential to devise a key for identifying which species have a venom apparatus. The findings presented here integrate molecular phylogeny and the evolution of character traits to infer the presence or absence of the venom apparatus in the Terebridae. Using a combined dataset …

Pointcut Rejuvenation: Recovering Pointcut Expressions In Evolving Aspect-Oriented Software, Raffi Khatchadourian, Phil Greenwood, Awais Rashid, Guoqing Harry Xu

Publications and Research

Pointcut fragility is a well-documented problem in Aspect-Oriented Programming; changes to the base-code can lead to join points incorrectly falling in or out of the scope of pointcuts. We present an automated approach that limits fragility problems by providing mechanical assistance in pointcut maintenance. The approach is based on harnessing arbitrarily deep structural commonalities between program elements corresponding to join points selected by a pointcut. The extracted patterns are then applied to later versions to offer suggestions of new join points that may require inclusion. We demonstrate the usefulness of our technique by rejuvenating pointcuts in multiple versions of several …

Contributing Factors To Pointcut Fragility, Phil Greenwood, Awais Rashid, Raffi Khatchadourian

Publications and Research

Pointcut fragility is a well-documented problem of Aspect-Oriented Programming with changes to the base-code causing join points to incorrectly fall in or out of scope. In order to combat this problem a tool was developed that provides mechanical assistance to pointcut maintenance. This tool relied on the deep structural commonalities between program elements to detect when pointcut fragility occurs. During the assessment of this tool a number of common practices were uncovered that were employed both in the aspect and base-code that contributed to or prevented pointcut fragility. This paper documents the practices uncovered and describes how they can affect …

Quantum Computing: Selected Internet Resources For Librarians, Researchers, And The Casually Curious, Jill Cirasella

Publications and Research

This article is an annotated selection of the most important and informative Internet resources for learning about quantum computing, finding quantum computing literature, and tracking quantum computing news.

The Maximum Rectilinear Crossing Number Of The N Dimensional Cube Graph, Matthew Alpert, Elie Feder, Heiko Harborth, Sheldon Klein

Publications and Research

We find a.nd prove the maximum rectilinear crossing n1.1mber of the three-dimensional cube graph (Q₃). We demonstrate a method of drawing then-cube graph, Q_n., with many crossings, and thus find a lower bound for the maximum rectilinear crossing number of Q_n. We conjecture that this bound is sharp. We also prove an upper bound for the maximum rectilinear crossing number of Q_n.

The Most Effective Statistical Approach To Correct Environmental Satellite Data, Md Zahidur Rahman, Leonid Roytman

Publications and Research

The proposed paper apply novel statistical approach to correct radiometric data measured by Advanced Very High Resolution Radiometers (AVHRR) onboard the National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites (POES). This paper investigates Normalized Difference Vegetation Index (NDVI) stability in the NOAA/NESDIS Global Vegetation Index (GVI) data during 1982-2003. AVHRR weekly data for the five NOAA afternoon satellites for the China dataset is studied, for it includes a wide variety of different ecosystems represented globally. It was found that data for the years 1988, 1992, 1993, 1994, 1995 and 2000 are not stable enough compared to other years …

Lattice Operators And Topologies, Eva Cogan

Publications and Research

Working within a complete (not necessarily atomic) Boolean algebra, we use a sublattice to define a topology on that algebra. Our operators generalize complement on a lattice which in turn abstracts the set theoretic operator. Less restricted than those of Banaschewski and Samuel, the operators exhibit some surprising behaviors. We consider properties of such lattices and their interrelations. Many of these properties are abstractions and generalizations of topological spaces. The approach is similar to that of Bachman and Cohen. It is in the spirit of Alexandroff, Frolík, and Nöbeling, although the setting is more general. Proceeding in this manner, we …

The Maximum Of The Maximum Rectilinear Crossing Numbers Of D-Regular Graphs Of Order N, Matthew Alpert, Elie Feder, Heiko Harborth

Publications and Research

We extend known results regarding the maximum rectilinear crossing number of the cycle graph (Cn) and the complete graph (Kn ) to the class of general d-regular graphs Rn,d. We present the generalized star drawings of the d-regular graphs Sn,d of order n where n + d ≡ 1 (mod 2) and prove that they maximize the maximum rectilinear crossing numbers. A star-like drawing of Sn,d for n ≡ d ≡ 0 (mod 2) is introduced and we conjecture that this drawing maximizes the maximum rectilinear crossing numbers, too. We offer a simpler proof of two results initially proved by …

Quirky, Not Quacky: Quantum Computing For Librarians, Jill Cirasella

Publications and Research

This slideshow introduces librarians and non-scientists to the relatively young field of quantum computing.

Specifying Reusable Aspects, Neelam Soundarajan, Raffi Khatchadourian

Publications and Research

Aspect-Oriented Programming enables developers to manage, in a more modular fashion, implementations of crosscutting concerns that might be scattered or tangled if aspect-oriented techniques were not utilized. Our interest in this paper is in considering techniques for specifying precise properties of aspects. In particular, we are interested in specifying reusable aspects; i.e., aspects that correspond to crosscutting concerns that occur in many systems. These abstract aspects can be reused in various systems where a particular concern is applicable. Although there has been work on issues related to reasoning about aspects and the behaviors of aspect-oriented systems, specifying reusable abstract aspects …

The Orchard Crossing Number Of An Abstract Graph, Elie Feder, David Garber

Publications and Research

.We introduce the Orchard crossing number, which is defined in a similar way to the well-known rectilinear crossing number. We compute the Orchard crossing number for some simple families of graphs. We also prove some properties of this crossing number.

Moreover, we define a variant of this crossing number which is tightly connected to the rectilinear crossing number, and compute it for some simple families of graphs.

Phenyl-Substituted Siloxane Hybrid Gels That Soften Below 140[Degrees]C, Andrei Jitianu, Glenn Amatucci, Lisa C. Klein

Publications and Research

A characteristic of so-called melting gels is that the gels, which are rigid at room temperature, are able to soften and resoften at temperatures around 110 [degrees]C. However, after consolidation at temperatures higher than 150 [degrees]C, the gels no longer resoften. Two systems of melting gels were investigated: phenyltrimethoxysilane (PhTMS)–diphenyldimethoxysilane (DPhDMS) and phenyltriethoxysilane (PhTES)–diphenyldiethoxysilane (DPhDES). The influence of disubstituted versus monosubstituted alkoxide on the softening behavior and the temperature of decomposition was studied. The consolidation temperature increased as the amount of disubstituted alkoxide increased, while the decomposition temperature increased only slightly. In general, the ethoxy-containing gels (maximum at 150[degrees]C) consolidated …

Series That Probably Converge To One, Thomas J. Pfaff, Max Tran

Publications and Research

No abstract provided.

Flocking In The Time-Dissonance Plane, Adam James Wilson

Publications and Research

This paper describes a technique for the sonification of an idealized model of the flocking behavior of birds, fish, and insects. Flocking agents are represented by pitches that move through time to produce chords of variable dissonance. The objective of each agent is to move toward more consonant chord formations with other agents. The output of the sonification is intended to provide material for use in musical composition.

A Symbolic Sonification Of L-Systems, Adam James Wilson

Publications and Research

This paper describes a simple technique for the sonification of branching structures in plants. The example is intended to illustrate a qualitative definition of best practices for sonification aimed at the production of musical material. Visually manifest results of tree growth are modelled and subsequently mapped to pitch, time, and amplitude. Sample results are provided in symbolic music notation.

An Analysis Of Entries In The First Tac Market Design Competition, Jinzhong Niu, Kai Cai, Peter Mcburney, Simon Parsons

Publications and Research

This paper presents an analysis of entries in the first TAC Market Design Competition final that compares the entries across several scenarios. The analysis complements previous work analyzing the 2007 competition, demonstrating some vulnerabilities of entries that placed highly in the competition. The paper also suggests a simple strategy that would have performed well.

On The Assessment Of Pointcut Design In Evolving Aspect-Oriented Software, Raffi Khatchadourian, Phil Greenwood, Awais Rashid

Publications and Research

No abstract provided.

Rejuvenate Pointcut: A Tool For Pointcut Expression Recovery In Evolving Aspect-Oriented Software, Raffi Khatchadourian, Awais Rashid

Publications and Research

Aspect-oriented programming (AOP) strives to localize the scattered and tangled implementations of crosscutting concerns (CCCs) by allowing developers to declare that certain actions (advice) should be taken at specific points (join points) during the execution of software where a CCC (an aspect) is applicable. However, it is non-trivial to construct optimal pointcut expressions (a collection of join points) that capture the true intentions of the programmer and, upon evolution, maintain these intentions. We demonstrate an AspectJ source-level inferencing tool called rejuvenate pointcut which helps developers maintain pointcut expressions over the lifetime of a software product. A key insight into the …

The Contribution Of Advective Fluxes To Net Ecosystem Exchange In A High-Elevation, Subalpine Forest, Chuixiang Yi, Dean E. Anderson, Andrew A. Turnipseed, Sean P. Burns, Jed P. Sparks, David I. Stannard, Russell K. Monson

Publications and Research

The eddy covariance technique, which is used in the determination of net ecosystem CO₂ exchange (NEE), is subject to significant errors when advection that carries CO₂ in the mean flow is ignored. We measured horizontal and vertical advective CO₂ fluxes at the Niwot Ridge AmeriFlux site (Colorado, USA) using a measurement approach consisting of multiple towers. We observed relatively high rates of both horizontal (F_hadv) and vertical (F_vadv) advective fluxes at low surface friction velocities (u_*) which were associated with downslope katabatic flows. We observed that F_hadv was confined to …

Keeping Abreast Of Quantum News: Quantum Computing On The Web And In The Literature, Jill Cirasella

Publications and Research

This appendix describes tools that can help you track developments in quantum computing.

Historical Bibliography Of Quantum Computing, Jill Cirasella

Publications and Research

This bibliographic essay reviews seminal papers in quantum computing. Although quantum computing is a young science, its researchers have already published thousands of noteworthy articles, far too many to list here. Therefore, this appendix is not a comprehensive chronicle of the emergence and evolution of the field but rather a guided tour of some of the papers that spurred, formalized, and furthered its study.