1,178 research outputs found
The Hazen Mammoth (Mammuthus columbi), Prairie County, Arkansas
In May 1965, mammoth remains were exposed during the excavation of a borrow pit for construction of Interstate Highway 40, 2 mi northeast of Hazen, Prairie County, Arkansas. The proboscidian remains consisted of a skull with tusks, mandibles, atlas and other skeletal elements. The vertebra material was scattered over approximately 150 m (1,600 sq ft) but was confined to a layer of red clayey-silt 6.7 m (22 ft) below the surface. No additional fauna or flora was recovered. The mammoth remains are referred to Mammuthus columbi (Falconer, 1857) on the basis of characteristics of the dentition, particularly the comparison of index of hypsodonty to functional plate density. Mammuthus columbi was widely distributed in southeast North America during the late part of the Pleistocene Epoch (Sangamon-Wisconsin Stages)
Harmonic oscillator in a background magnetic field in noncommutative quantum phase-space
We solve explicitly the two-dimensional harmonic oscillator and the harmonic
oscillator in a background magnetic field in noncommutative phase-space without
making use of any type of representation. A key observation that we make is
that for a specific choice of the noncommutative parameters, the time reversal
symmetry of the systems get restored since the energy spectrum becomes
degenerate. This is in contrast to the noncommutative configuration space where
the time reversal symmetry of the harmonic oscillator is always broken.Comment: 7 pages Late
On the uniqueness of the unitary representations of the non commutative Heisenberg-Weyl algebra
In this paper we discuss the uniqueness of the unitary representations of the
non commutative Heisenberg-Weyl algebra. We show that, apart from a critical
line for the non commutative position and momentum parameters, the Stone-von
Neumann theorem still holds, which implies uniqueness of the unitary
representation of the Heisenberg-Weyl algebra.Comment: 4 page
Variations on the Planar Landau Problem: Canonical Transformations, A Purely Linear Potential and the Half-Plane
The ordinary Landau problem of a charged particle in a plane subjected to a
perpendicular homogeneous and static magnetic field is reconsidered from
different points of view. The role of phase space canonical transformations and
their relation to a choice of gauge in the solution of the problem is
addressed. The Landau problem is then extended to different contexts, in
particular the singular situation of a purely linear potential term being added
as an interaction, for which a complete purely algebraic solution is presented.
This solution is then exploited to solve this same singular Landau problem in
the half-plane, with as motivation the potential relevance of such a geometry
for quantum Hall measurements in the presence of an electric field or a
gravitational quantum well
Formulation, Interpretation and Application of non-Commutative Quantum Mechanics
In analogy with conventional quantum mechanics, non-commutative quantum
mechanics is formulated as a quantum system on the Hilbert space of
Hilbert-Schmidt operators acting on non-commutative configuration space. It is
argued that the standard quantum mechanical interpretation based on Positive
Operator Valued Measures, provides a sufficient framework for the consistent
interpretation of this quantum system. The implications of this formalism for
rotational and time reversal symmetry are discussed. The formalism is applied
to the free particle and harmonic oscillator in two dimensions and the physical
signatures of non commutativity are identified.Comment: 11 page
Leveraging the fully integrated supply chain
Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2004."June 2004."Includes bibliographical references (leaves 65-69).(cont.) in the success of Lucent's turnaround and, from the patterns that emerge, a basis for a new holistic framework for designing and leveraging an integrated supply chain is offered. This framework suggests that attaining competitive advantage from supply chain capabilities lies in a firm's ability to incorporate corporate culture, leadership style, organization structure and both inter and intra tier governance methods into it's supply chain design in order to enable an integrated and extended organization where the channel expert can be identified and engaged in decision making in a natural, real-time and organic process.Over the past three years, in response to dramatic changes in the telecommunications industry, Lucent Technologies has realigned its corporate strategy from being a provider of manufacturing excellence to one of supply chain excellence. Supported by this realignment, Lucent has recently returned to profitability after eleven consecutive losing quarters, and has posted dramatic improvements in financial, operational and customer satisfaction metrics. Lucent's new strategy is focused on leveraging its supply chain capabilities to create a new extended enterprise that is both customer and supplier intimate, and operates as a broad reaching cross-functional Supply Chain Networks (SCN) organization. Pivotal to the success of this realignment was extending the scope of Lucent's supply chain activities, both internally and externally to the company. Internally, Lucent integrated such non-traditional SCM activities as sales, product design, and margin management into its newly created SCN organization. Externally, by outsourcing virtually all of its manufacturing, and much of the associated supplier management, to Electronics Manufacturing Services (EMS) partners, Lucent became responsible for the orchestration of an extended multi-tier supply chain that integrated abilities and expertise of functional teams within Lucent and within its EMS partners, raw component suppliers and customers. In this thesis, the Supply Chain Networks transformation at Lucent is examined in the broader context of the changes that took place in Lucent's: organizational model; leadership team; corporate culture; customer and supplier relationships; operations; and market space. The change that was effected in each of these areas is reviewed for its roleby Duncan M.L. Scholtz.M.Eng.in Logistic
The last continuous grasslands on Earth: Identification and conservation importance
Grasslands are the most threatened and least protected biome. Yet, no study has been conducted to identify the last remaining continuous grasslands on Earth. Here, we used World Wildlife Fund (WWF) and International Union for Conservation of Nature (IUCN) classifications to measure the degree of intactness remaining for the world\u27s grassland ecoregions. This analysis revealed three findings of critical conservation importance. First, only a few large, intact grasslands remain. Second, every continent with a grassland ecoregion considered in this study contains at least one relatively intact grassland ecoregion. Third, the largest remaining continuous grasslands identified in this analysis have persisted despite last centuries anthropogenic pressures and have the best chance to withstand 21st century pressures of global change. We discuss how these regions are of critical conservation importance to global grassland conservation efforts under anthropogenically driven global change. They provide essential ecosystem services, play an important role in mitigating the effects of climate change, serve as critical repositories for grassland biodiversity, are foundational for continental migration pathways, hold unique cultural heritage, and people\u27s livelihoods depend upon their persistence
On the role of twisted statistics in the noncommutative degenerate electron gas
We consider the problem of a degenerate electron gas in the background of a
uniformly distributed positive charge, ensuring overall neutrality of the
system, in the presence of non-commutativity. In contrast to previous
calculations that did not include twisted statistics, we find corrections to
the ground state energy already at first order in perturbation theory when the
twisted statistics is taken into account. These corrections arise since the
interaction energy is sensitive to two particle correlations, which are
modified for twisted anti-commutation relations
The N=1 Supersymmetric Landau Problem and its Supersymmetric Landau Level Projections: the N=1 Supersymmetric Moyal-Voros Superplane
The N=1 supersymmetric invariant Landau problem is constructed and solved. By
considering Landau level projections remaining non trivial under N=1
supersymmetry transformations, the algebraic structures of the N=1
supersymmetric covariant non(anti)commutative superplane analogue of the
ordinary N=0 noncommutative Moyal-Voros plane are identified
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