Excitations of the static quark-antiquark system in several gauge theories

The spectrum of gluons in the presence of a static quark-antiquark pair is studied using Monte Carlo simulations on anisotropic space-time lattices. For very small quark-antiquark separations R, the level orderings and approximate degeneracies disagree with the expectations from an effective string theory. As the quark-antiquark separation R increases, a dramatic rearrangement of the energies occurs, and above 2 fm, all of the levels studied show behavior consistent with an effective string description. The energy spacings are nearly pi/R, but a tantalizing fine structure remains. In addition to 4-dimensional SU(3) gauge theory, results from 3-dimensional SU(2) and compact U(1) gauge theories are also presented.Comment: 12 pages, 4 figures, talk presented at the International Conference on Color Confinement and Hadrons in Quantum Chromodynamics (Confinement 2003), RIKEN, July 21-24, 200

The heavy-quark hybrid meson spectrum in lattice QCD

Recent findings on the spectrum of heavy-quark mesons from computer simulations of quarks and gluons in lattice QCD are summarized, with particular attention to quark-antiquark states bound by an excited gluon field. The validity of a Born-Oppenheimer treatment for such systems is discussed. Recent results on glueball masses, the light-quark 1-+ hybrid meson mass, and the static three-quark potential are summarized.Comment: 15 pages, 13 figures, talk given at the Workshop on Scalar Mesons: An Interesting Puzzle for QCD, SUNY Institute of Technology, Utica, NY, May 16-18, 2003, submitted to American Institute of Physics Conference Proceedings. After publication, it will be found at http://proceedings.aip.org/proceedings

Malleable coding for updatable cloud caching

In software-as-a-service applications provisioned through cloud computing, locally cached data are often modified with updates from new versions. In some cases, with each edit, one may want to preserve both the original and new versions. In this paper, we focus on cases in which only the latest version must be preserved. Furthermore, it is desirable for the data to not only be compressed but to also be easily modified during updates, since representing information and modifying the representation both incur cost. We examine whether it is possible to have both compression efficiency and ease of alteration, in order to promote codeword reuse. In other words, we study the feasibility of a malleable and efficient coding scheme. The tradeoff between compression efficiency and malleability cost-the difficulty of synchronizing compressed versions-is measured as the length of a reused prefix portion. The region of achievable rates and malleability is found. Drawing from prior work on common information problems, we show that efficient data compression may not be the best engineering design principle when storing software-as-a-service data. In the general case, goals of efficiency and malleability are fundamentally in conflict.This work was supported in part by an NSF Graduate Research Fellowship (LRV), Grant CCR-0325774, and Grant CCF-0729069. This work was presented at the 2011 IEEE International Symposium on Information Theory [1] and the 2014 IEEE International Conference on Cloud Engineering [2]. The associate editor coordinating the review of this paper and approving it for publication was R. Thobaben. (CCR-0325774 - NSF Graduate Research Fellowship; CCF-0729069 - NSF Graduate Research Fellowship)Accepted manuscrip

Does the environment in which ICT-based market information services (MIS) projects operate affect their performance? Experiences from Kenya

The need to provide agricultural information to farmers has led to emergence of numerous ICTbased MIS projects in developing country. These projects aim at promoting commercialization of smallholder agriculture and subsequently their welfare. This study examines the how the environment in which such ICT-based MIS affect their performance. It specifically uses the DrumNet project, an ICT-based MIS, to assess how the socio-economic, physical, political and physical environment in the project areas affected its performance. The study finds that those transaction-related problems, especially strategic default, deriving from these environmental factors greatly undermined the performance of DrumNet forcing it to relocate severally. It discusses policy implications of these findings.ICT-based MIS projects, the DrumNet model, operational environment, performance, Kenya, Research Methods/ Statistical Methods,

Malleable Coding with Fixed Reuse

In cloud computing, storage area networks, remote backup storage, and similar settings, stored data is modified with updates from new versions. Representing information and modifying the representation are both expensive. Therefore it is desirable for the data to not only be compressed but to also be easily modified during updates. A malleable coding scheme considers both compression efficiency and ease of alteration, promoting codeword reuse. We examine the trade-off between compression efficiency and malleability cost-the difficulty of synchronizing compressed versions-measured as the length of a reused prefix portion. Through a coding theorem, the region of achievable rates and malleability is expressed as a single-letter optimization. Relationships to common information problems are also described

On palimpsests in neural memory: an information theory viewpoint

The finite capacity of neural memory and the reconsolidation phenomenon suggest it is important to be able to update stored information as in a palimpsest, where new information overwrites old information. Moreover, changing information in memory is metabolically costly. In this paper, we suggest that information-theoretic approaches may inform the fundamental limits in constructing such a memory system. In particular, we define malleable coding, that considers not only representation length but also ease of representation update, thereby encouraging some form of recycling to convert an old codeword into a new one. Malleability cost is the difficulty of synchronizing compressed versions, and malleable codes are of particular interest when representing information and modifying the representation are both expensive. We examine the tradeoff between compression efficiency and malleability cost, under a malleability metric defined with respect to a string edit distance. This introduces a metric topology to the compressed domain. We characterize the exact set of achievable rates and malleability as the solution of a subgraph isomorphism problem. This is all done within the optimization approach to biology framework.Accepted manuscrip

The Casimir Energy Paradox of the QCD String

It is widely thought that the early onset of the asymptotic Casimir energy with unit conformal charge signals bosonic string formation of the confining flux connecting a static quark-antiquark pair in QCD. This is observed on a scale where most of the string eigenmodes do not exist and the few stable modes above the ground state are displaced. Hints for the resolution of this paradox are suggested.Comment: Lattice2003(topology

Boy Scouts Parade : March

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Awareness and use of m-banking services in agriculture: The case of smallholder farmers in Kenya

Smallholder farmer access to agricultural finance has been a major constraint to agricultural commercialization in developing countries. The ICT revolution in Africa has however brought an opportunity to ease this constraint. The mobile phone-based banking services that started in Kenya urban centers have spread to rural areas and even other countries. Using these services farmers could receive funds invest in agriculture finance transactions. This study examines the awareness and use of m-banking services among rural farmers in Kenya. It also assesses the factors conditioning the use of such services. The study finds high awareness of m-banking services among the smallholder farmers. It also finds that education, distance to a commercial bank, membership to farmer organizations, distance to the m-banking agents, and endowment with physical and financial assets affect the use of m-banking services. It discusses the implications of these findings for policy and practice.Mobile phones, m-banking services, awareness and use, smallholder farmers, Kenya, Financial Economics,