463 research outputs found
Making, probing and understanding Bose-Einstein condensates
Contribution to the proceedings of the 1998 Enrico Fermi summer school on
Bose-Einstein condensation in Varenna, Italy.Comment: Long review paper with ~90 pages, ~20 figures. 2 GIF figures in
separate files (4/5/99 fixed figure
Use of Markov Chains to Design an Agent Bidding Strategy for Continuous Double Auctions
As computational agents are developed for increasingly complicated e-commerce
applications, the complexity of the decisions they face demands advances in
artificial intelligence techniques. For example, an agent representing a seller
in an auction should try to maximize the seller's profit by reasoning about a
variety of possibly uncertain pieces of information, such as the maximum prices
various buyers might be willing to pay, the possible prices being offered by
competing sellers, the rules by which the auction operates, the dynamic arrival
and matching of offers to buy and sell, and so on. A naive application of
multiagent reasoning techniques would require the seller's agent to explicitly
model all of the other agents through an extended time horizon, rendering the
problem intractable for many realistically-sized problems. We have instead
devised a new strategy that an agent can use to determine its bid price based
on a more tractable Markov chain model of the auction process. We have
experimentally identified the conditions under which our new strategy works
well, as well as how well it works in comparison to the optimal performance the
agent could have achieved had it known the future. Our results show that our
new strategy in general performs well, outperforming other tractable heuristic
strategies in a majority of experiments, and is particularly effective in a
'seller?s market', where many buy offers are available
An agent-based approach to immune modelling
This study focuses on trying to understand why the range
of experience with respect to HIV infection is so diverse, especially as regards to the latency period. The challenge is to determine what assumptions can be made about the nature of the experience of antigenic invasion and diversity that can be modelled, tested and argued plausibly.
To investigate this, an agent-based approach is used to extract high-level behaviour which cannot be described analytically from the set of interaction rules at the cellular level. A prototype model encompasses local variation in baseline properties contributing to the individual disease experience and is included in a network which mimics the chain of lymphatic nodes. Dealing with massively multi-agent systems requires major computational efforts. However, parallelisation methods are a natural
consequence and advantage of the multi-agent approach. These are implemented using the MPI library
Chen-Ruan cohomology of ADE singularities
We study Ruan's \textit{cohomological crepant resolution conjecture} for
orbifolds with transversal ADE singularities. In the -case we compute both
the Chen-Ruan cohomology ring and the quantum corrected
cohomology ring . The former is achieved in general, the
later up to some additional, technical assumptions. We construct an explicit
isomorphism between and in the -case,
verifying Ruan's conjecture. In the -case, the family
is not defined for . This implies that
the conjecture should be slightly modified. We propose a new conjecture in the
-case which we prove in the -case by constructing an explicit
isomorphism.Comment: This is a short version of my Ph.D. Thesis math.AG/0510528. Version
2: chapters 2,3,4 and 5 has been rewritten using the language of groupoids; a
link with the classical McKay correpondence is given. International Journal
of Mathematics (to appear
Note and Comment
New Trials for Technical Errors - A witness called to testify is presumed to be of good character. Hence no proof of it is necessary. But out of abundant caution this presumption is fortified by evidence. The witness is thus shown to be in fact exactly what the law presumes him to be. Result-the case is reversed for the commission of this grave and prejudicial error.-Lockett v. State (Ark. 1918), 207 S. W. 55
Note and Comment
James H. Brewster - Thousands of alumni and former students of the Law School will learn with deep regret of the sudden death of Professor Brewster in Denver, Colorado, on October 7, 1920
Note and Comment
Estates in Fee Tail - Quite generally estates in fee tail under the STATUTE DE DONIS were recognized by the states as a part of the common law. Statutory provisions in the way of modification and abolishment of such estates, however, are very common. The nature and scope of the statutory provisions have varied. See the states classified according to the character of the legislation in BREWSTER, CONVEYANCING, § § 142, 143
Note and Comment
The Law School - In common with all other law schools requiring college work for admission, this school has suffered a very heavy loss in attendance because of war conditions. This, however, is a matter for pride and not for discouragement for it means that our students have gone into the army or navy or other branches of the national service in very high ratio to their total number. And this is by no means due only to the effect of the Selective Service Act for from the very beginning our men have volunteered in great spirit and promptness. In 1917 fewer than two-thirds of the then senior class were present at the Commencement exercises to receive their degrees. Most of them had gone by the middle of May. All this indicates that the profession is living up to one of its high traditions of patriotic service
Staphylococcal cassette chromosome mec containing a novel mec gene complex, B4
OBJECTIVES: To describe a new subclass of mec class B complex identified in Staphylococcus epidermidis. METHODS: Four S. epidermidis isolates obtained from bloodstream infections in patients at University Medical Center Groningen (UMCG) were analysed by phenotypic antibiotic susceptibility testing and WGS. RESULTS: Sequence analysis revealed a new staphylococcal cassette chromosome mec (SCCmec) structure in isolate UMCG335. In this structure, plasmid pUB110 was found to be integrated into SCCmec IVc, creating a new SCCmec subtype, IVUMCG335. SCCmec IVc and a copy of plasmid pUB110 were found in other isolates, UMCG364 and UMCG341, respectively, indicating a probability that SCCmec IVUMCG335 could have evolved at the UMCG. SCCmec of UMCG337 contained a new genetic organization of the mec complex (IS431-ΔmecR1-mecA-IS431-pUB110-IS431-ψIS1272) that we have named B4. This new subclass of mec class B complex originated by IS431-mediated inversion of the DNA segment encompassing the plasmid and most of the genes of the mec complex with the exception of IS1272. As the SCCmec organization in UMCG337 differed by the inversion of an ∼10 kb sequence compared with SCCmec IVUMCG335, we have named it SCCmec subtype IVUMCG337. Isolates UMCG335 and UMCG337 carrying SCCmec IVUMCG335 and IVUMCG337, respectively, were associated with a restriction-modification system and a CRISPR-Cas system, creating a composite island of almost 70 kb. CONCLUSIONS: Our findings highlight the importance of IS431 in the evolution of the SCCmec region. The increasing genetic diversity identified in the SCCmec elements imposes a great challenge for SCCmec typing methods and highlights possible difficulties with the SCCmec nomenclature
Long-Term Stability of an Area-Reversible Atom-Interferometer Sagnac Gyroscope
We report on a study of the long-term stability and absolute accuracy of an
atom interferometer gyroscope. This study included the implementation of an
electro-optical technique to reverse the vector area of the interferometer for
reduced systematics and a careful study of systematic phase shifts. Our data
strongly suggests that drifts less than 96 deg/hr are possible after
empirically removing shifts due to measured changes in temperature, laser
intensity, and several other experimental parameters.Comment: 4 pages, 4 figures, submitted to PR
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