620 research outputs found
Electric field and temperature-induced removal of moisture in nanoporous organosilicate films
doi:10.1063/1.1757019The effects of bias-temperature-stress (BTS) or simply temperature-stress (TS) on nanoporous low-k methylsilsesquioxane films are studied. Initially, the as-given and O2 ashed/etched films exhibit physical adsorption of moisture as revealed from the electrical behavior of the samples after 15 days. The temperature stressing at 170â°C volatilized the adsorbed water but is unable to remove chemisorb and hydrophillic Si-OH groups. As a result, the TS films remain susceptible to moisture. BTS at 170â°C also removes adsorbed water. More important, the surfaces under the metal-insulator structure were dehydroxylated by breaking the chemisorb Si-OH group facilitating the formation of siloxane bonds that prevents adsorption of moisture even after 60 days.The authors would like to acknowledge Dorel Toma of TEL for providing the samples, and SRC and NSF for funding this research
Roles of Social Conformity in Deviance in Poverty: A Study on Working Poverty and Educational Investment in Bangladesh
In recent decades the Indian subcontinent has displayed remarkable invariance in the incidence of working poverty despite strong economic performance. It is widely held that education can rescue households from various types of poverty traps created by information problems and incorrect expectations. Yet very little is known about the motivation of the working poor in acquiring education. From a field study conducted in Bangladesh, this paper provides invaluable insights for the first time, to our best understanding, into the factors that shape the decision of a poor household to care about and respond to educational decisions of others in one's community. Based on the Choice-Theoretic Framework of Rational Emulation and Deviance , this paper empirically explains why some households choose to copy others, while some choose deviance even though social deviance in acquiring education can throw subjects into abject poverty. In particular, the paper examines the determinants of the (individual) educational expenditure of a household sheltering the working poor
Network Management System for (FUTON-like) Radio-over- Fiber Infrastructure
EU-Project FUTON Radio-over-Fiber (RoF) infrastructure proposes high transmission rates at small antenna costs, implying competitive CAPEX for next generation networks. But to be cost-efficient, it needs to employ new network architectures and intelligent technology solutions for decreasing network operational costs. The RoF Network Manager manages the network equipment on the optical front haul between the Central Unit (CU) and all Remote Antenna Units (RAU)s connected by it, as well as the communication links, while enabling end-to-end service problem resolution and service quality management by the FUTON Middleware. Although a significant amount of prior research work can be found in the literature related to RoF, there is still significant lack of technologies concerning RoF networks management. RoF Manager and its sub-systems target to fill such gap, proposing a novel concept in the form of Channel Forwarding Table (CFT). RoF Manager follows an autonomous and generic network management framework, designed to be scalable in terms of adding new network elements (NEs). It targets multitechnology, multi-service and multi-vendor NEs in the network using Simple Network Management Protocol (SNMP). It can also provide alternative paths in case of failure. This work puts forward a new paradigm towards RoF management solution managing network performance, network faults, network security and configurations for convergent networks
Transport properties of one-dimensional Kronig-Penney models with correlated disorder
Transport properties of one-dimensional Kronig-Penney models with binary
correlated disorder are analyzed using an approach based on classical
Hamiltonian maps. In this method, extended states correspond to bound
trajectories in the phase space of a parametrically excited linear oscillator,
while the on site-potential of the original model is transformed to an external
force. We show that in this representation the two probe conductance takes a
simple geometrical form in terms of evolution areas in phase-space. We also
analyze the case of a general N-mer model.Comment: 16 pages in Latex, 12 Postscript figures include
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
One-loop effects in a self-dual planar noncommutative theory
We study the UV properties, and derive the explicit form of the one-loop
effective action, for a noncommutative complex scalar field theory in 2+1
dimensions with a Grosse-Wulkenhaar term, at the self-dual point. We also
consider quantum effects around non-trivial minima of the classical action
which appear when the potential allows for the spontaneous breaking of the U(1)
symmetry. For those solutions, we show that the one-loop correction to the
vacuum energy is a function of a special combination of the amplitude of the
classical solution and the coupling constant.Comment: Version to appear in JHE
Noncommutativity In The Mechanics Of A Free Massless Relativistic Particle
We show the existence of a noncommutative spacetime structure in the context
of a complete discussion on the underlying spacetime symmetries for the
physical system of a free massless relativistic particle. The above spacetime
symmetry transformations are discussed for the first-order Lagrangian of the
system where the transformations on the coordinates, velocities and momenta
play very important roles. We discuss the dynamics of this system in a
systematic manner by exploiting the symplectic structures associated with the
four dimensional (non-)commutative cotangent (i.e. momentum phase) space
corresponding to a two dimensional (non-)commutative configuration (i.e.
target) space. A simple connection of the above noncommutativity (NC) is
established with the NC associated with the subject of quantum groups where
transformations play a decisive role.Comment: LaTeX file, 19 page
Outcome of pterygium surgery: analysis over 14 years
Aim: To report the outcome of pterygium surgery performed at a tertiary eye care centre in South India. Methods: Retrospective analysis of medical records of 920 patients (989 eyes) with primary and recurrent pterygia operated between January 1988 and December 2001. The demographic variables, surgical technique (bare sclera, primary closure, amniotic membrane transplantation (AMT), conjunctival autograft (CAG), conjunctival-limbal autograft (CLAG), or surgical adjuvants), recurrences and postoperative complications were analysed. Results: A total of 496 (53.9%) were male and 69 (7.5%) had bilateral pterygia. Bare sclera technique was performed in 267 (27.0%) eyes, primary conjunctival closure in 32 (3.2%), AMG in 123 (12.4%), CAG in 429 (43.4%), and CLAG in 70 (7.1%). Adjuvant mitomycin C was used in 44 (4.4%) cases. The mean duration of follow-up was 8.917.0 and 5.98.8 months for unilateral primary and recurrent pterygia, respectively. The overall recurrence rate was 178 (18.0%). Following primary and recurrent unilateral pterygium excision respectively, recurrences were noted in 46 (19.4%) and 1 (33.3%) eyes after bare sclera technique, five (16.7%) and 0 after primary closure, 28 (26.7%) and 0 with AMG, 42 (12.2%) and five (31.3%) with CAG, and nine (17.3%) and two (40%) with CLAG. Recurrences were significantly more in males with primary (23.3 vs10.7%, P<0.0001) and recurrent (26.7 vs0%, P=0.034) pterygia, and in those below 40 years (25.2 vs14.8%, P=0.003). Conclusion: CAG appears to be an effective modality for primary and recurrent pterygia. Males and patients below 40 years face greater risk of recurrence. Bare sclera technique has an unacceptably high recurrence. Prospective studies comparing CAG, CLAG, and AMG for primary and recurrent pterygia are needed
Polypyrrole-Fe2O3 nanohybrid materials for electrochemical storage
We report on the synthesis and electrochemical characterization of nanohybrid polypyrrole (PPy) (PPy/Fe2O3) materials for electrochemical storage applications. We have shown that the incorporation of nanoparticles inside the PPy notably increases the charge storage capability in comparison to the âpureâ conducting polymer. Incorporation of large anions, i.e., paratoluenesulfonate, allows a further improvement in the capacity. These charge storage modifications have been attributed to the morphology of the composite in which the particle sizes and the specific surface area are modified with the incorporation of nanoparticles. High capacity and stability have been obtained in PC/NEt4BF4 (at 20 mV/s), i.e., 47 mAh/g, with only a 3% charge loss after one thousand cyles. The kinetics of chargeâdischarge is also improved by the hybrid nanocomposite morphology modifications, which increase the rate of insertionâexpulsion of counter anions in the bulk of the film. A room temperature ionic liquid such as imidazolium trifluoromethanesulfonimide seems to be a promising electrolyte because it further increases the capacity up to 53 mAh/g with a high stability during chargeâdischarge processes
Hawking radiation, W-infinity algebra and trace anomalies
We apply the "trace anomaly method" to the calculation of moments of the
Hawking radiation of a Schwarzschild black hole. We show that they can be
explained as the fluxes of chiral currents forming a W-infinity algebra. Then
we construct the covariant version of these currents and verify that up to
order 6 they are not affected by any trace anomaly. Using cohomological methods
we show that actually, for the fourth order current, no trace anomalies can
exist. The results reported here are strictly valid in two dimensions.Comment: 22 pages, typos correcte
- âŠ