Calculating Breadth of Knowledge

Since the advent of computers, information systems have grown in terms of the quantity of knowledge they deal with. Advances in data management are on the critical path for usability of these systems. This paper reports on a novel approach to an important problem; that of calculating the conceptual breadth of knowledge or data in a knowledge base or database. Breadth determination is useful in that ascribing meta-level knowledge of conceptual content can help to predict, for example, the validity of the closed-world assumption or the likelihood of encountering new information of a particular type. The point at which a system determines it is likely to have breadth in a given knowledge area may also serve as the trigger point for calculations that assume relatively complete knowledge in that area. The accurate determination of when a system has complete knowledge in an area is crucial for the accurate application of many AI algorithms

The Unmet Legal Needs of the Poor in Maine: Is Mandatory Pro Bono The Answer?

In 1989, the Maine Commission on Legal Needs was formed to study the civil legal needs of Maine\u27s poor population and to develop a plan for meeting those needs. Similar projects have been undertaken in a number of other states and by the American Bar Association in recent years. Each study has revealed a significant unmet need among the poor for assistance with legal problems. There seems little doubt that the situation is serious and widespread. The difficulty lies in finding a solution. One proposal that has been advanced is mandatory pro bono, a program that would require attorneys to give uncompensated legal assistance to the needy. For years debate over this proposal has focused on whether such a program would violate the constitutional rights of attorneys. The debate has intensified with the recent group of studies highlighting the unmet legal needs of the poor. This Comment will review the civil legal needs of Maine\u27s poor and the currently available resources for meeting those needs. It will then consider the legal issues involved in requiring counsel to undertake representation of people unable to afford an attorney in civil cases. Do courts have the authority to require attorneys to represent those unable to pay? Although neither the United States Supreme Court nor the Maine Supreme Judicial Court has addressed the issue, a review of available case law and legal commentaries suggests that courts very likely do have such authority. This Comment concludes, however, that other approaches should be tried in Maine before requiring attorneys to take pro bono civil cases

Spontaneous Retrieval in a Conceptual Information System

A traditional paradigm for retrieval from a conceptual knowledge base is to gather up indices or features used to discriminate among or locate items in memory, and then perform a retrieval operation to obtain matching items. These items may then be evaluated for their degree of match against the input. This type of approach to retrieval has some problems. It requires one to look explicitly for items in memory whenever the possibility exists that there might be something of interest there. Also,this approach does not easily tolerate discrepancies or omissions in the input features or indices. In a question-answering system, a user may make incorrect assumptions about the contents of the knowledge base. This makes a tolerant retrieval method even more necessary.An alternative, two-stage model of conceptual information retrieval is proposed.The first stage is a spontaneous retrieval that operates by a simple marker-passing scheme. It is spontaneous because items are retrieved a£ a by-product of the input understanding process. The second stage is a graph matching process that filters or evaluates items retrieved by the first stage. This scheme has been implemented in the SCISOR information retrieval system. It is successful in overcoming problems of retrieval failure due to omitted indices, and also facilitates the construction of appropriate responses to a broader range of inputs

High-Resolution, Real-Space Imaging of Conformational Structures of Poly-L-Proline Helixes

In 1954, Edsall postulated that the imino-acid proline, which is a frequently found constituent of protein molecules, is a key determinant to the three-dimensional architecture of proteins. It not only should play a fundamental role in stabilizing helical structures of polypeptides, it should allow for sharp bends and even for a complete reversal of the direction of a helix looping back on itself. No direct evidence has yet been published to prove this prediction. Using scanning tunneling microscopy, we have presented high-resolution, real-space images of two conformations of poly-L-proline, where one structure clearly exhibits the predicted 180° back-folding behavior. The measured length, 1.89 nm, of the repeating unit cells agrees with available X-ray data for poly-L-proline I with cis-peptide bonds. We further observe aggregated poly-L-proline II, consisting of highly-ordered, periodically and parallel-linked trans-peptide chains which are 2.4 nm apart from each other. Stacking of these aggregates with their orientation rotated by 90° is also observed

Are N=1 and N=2 supersymmetric quantum mechanics equivalent?

After recalling different formulations of the definition of supersymmetric quantum mechanics given in the literature, we discuss the relationships between them in order to provide an answer to the question raised in the title.Comment: 15 page

N-particle sector of quantum field theory as a quantum open system

We give an exposition of a technique, based on the Zwanzig projection formalism, to construct the evolution equation for the reduced density matrix corresponding to the n-particle sector of a field theory. We consider the case of a scalar field with a $g \phi^3$ interaction as an example and construct the master equation at the lowest non-zero order in perturbation theory.Comment: 12 pages, Late

Discovery of a 168.8 s X-ray pulsar transiting in front of its Be companion star in the Large Magellanic Cloud

We report the discovery of LXP169, a new high-mass X-ray binary (XRB) in the LMC. The optical counterpart has been identified and appears to exhibit an eclipsing light curve. We performed follow-up observations to clarify the eclipsing nature of the system. Energy spectra and time series were extracted from two XMM-Newton observations to search for pulsations, characterise the spectrum, and measure spectral and timing changes. Long-term X-ray variability was studied using archival ROSAT data. The XMM positions were used to identify the optical counterpart. We obtained UV to NIR photometry to characterise the companion, along with its 4000 d long I-band light curve. We observed LXP169 with Swift at two predicted eclipse times. We found a spin period of 168.8 s that did not change between two XMM observations. The X-ray spectrum, well characterised by a power law, was harder when the source was brighter. The X-ray flux of LXP169 is found to be variable by a factor of at least 10. The counterpart is highly variable on short and long timescales, and its photometry is that of an early-type star with a NIR excess. This classifies the source as a BeXRB pulsar. We observed a transit in the UV, thereby confirming that the companion star itself is eclipsed. We give an ephemeris for the transit of MJD 56203.877 + N*24.329. We propose and discuss the scenario where the matter captured from the companion's equatorial disc creates an extended region of high density around the neutron star (NS), which partially eclipses the companion as the NS transits in front of it. This is most likely the first time the compact object in an XRB is observed to eclipse its companion star. LXP169 would be the first eclipsing BeXRB, and a wealth of important information might be gained from additional observations, such as a measure of the possible Be disc/orbital plane misalignment, or the mass of the NS.Comment: Updated version of arXiv 1302.4665v1, accepted for publication in Astronomy and Astrophysics. 11 pages, 8 figures, 3 table

Algebraic characterization of X-states in quantum information

A class of two-qubit states called X-states are increasingly being used to discuss entanglement and other quantum correlations in the field of quantum information. Maximally entangled Bell states and "Werner" states are subsets of them. Apart from being so named because their density matrix looks like the letter X, there is not as yet any characterization of them. The su(2) X su(2) X u(1) subalgebra of the full su(4) algebra of two qubits is pointed out as the underlying invariance of this class of states. X-states are a seven-parameter family associated with this subalgebra of seven operators. This recognition provides a route to preparing such states and also a convenient algebraic procedure for analytically calculating their properties. At the same time, it points to other groups of seven-parameter states that, while not at first sight appearing similar, are also invariant under the same subalgebra. And it opens the way to analyzing invariant states of other subalgebras in bipartite systems.Comment: 4 pages, 1 figur

Discovery of SXP265, a Be/X-ray binary pulsar in the Wing of the Small Magellanic Cloud

We identify a new candidate for a Be/X-ray binary in the XMM-Newton slew survey and archival Swift observations that is located in the transition region of the Wing of the Small Magellanic Cloud and the Magellanic Bridge. We investigated and classified this source with follow-up XMM-Newton and optical observations. We model the X-ray spectra and search for periodicities and variability in the X-ray observations and the OGLE I-band light curve. The optical counterpart has been classified spectroscopically, with data obtained at the SAAO 1.9 m telescope, and photometrically, with data obtained using GROND at the MPG 2.2 m telescope. The X-ray spectrum is typical of a high-mass X-ray binary with an accreting neutron star. We detect X-ray pulsations, which reveal a neutron-star spin period of P = (264.516+-0.014) s. The source likely shows a persistent X-ray luminosity of a few 10^35 erg/s and in addition type-I outbursts that indicate an orbital period of ~146 d. A periodicity of 0.867 d, found in the optical light curve, can be explained by non-radial pulsations of the Be star. We identify the optical counterpart and classify it as a B1-2II-IVe star. This confirms SXP 265 as a new Be/X-ray binary pulsar originating in the tidal structure between the Magellanic Clouds.Comment: 11 pages, 12 figures, accepted for publication in MNRA