Electrically injected quantum-dot photonic crystal microcavity light sources

The design, fabrication, and characterization of an electrically injected quantum-dot photonic crystal microcavity light source are described. The optical gain in the GaAs/AlGaAs-based device is provided by self-organized InGaAs quantum dots with ground-state room-temperature emission at 1.1 microm. The carriers are injected directly into the photonic crystal microcavity, which contains approximately 50 dots, avoiding surface state recombination in the photonic crystal pattern. The spectral characteristics of a single-defect photonic crystal microcavity show a single 2 nm broad microcavity resonance. The output power is of the order of a few tens of nanowatts.     

Study of compressibility in vascular rheology

Summary Stresses and strains in vascular tissues are studied in the paper, considering the material to be nonlinearly viscoelastic and compressible. Structural anisotropy is also taken into account. A numerical study of the derived expressions shows that consideration of even a low compressibility for vascular material has got a significant effect on the nonlinear stress-field in vascular walls.

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Zusammenfassung In dieser Arbeit werden die Spannungen und Dehnungen in Blutgefäßen untersucht unter der Annahme, daß sich die Materialien nicht-linear viskoelastisch und kompressibel verhalten. Auch die Anisotropie der Struktur wird berücksichtigt. Die numerische Auswertung der abgeleiteten Ausdrücke zeigt, daß die Einbeziehung einer auch nur geringen Kompressibilität des Gewebematerials einen signifikanten Effekt auf das nicht-lineare Spannungsfeld in den Gefäßwänden ergibt.

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With 2 figures     

Phase diagram and critical exponents of a dissipative Ising spin chain in a transverse magnetic field

We consider a one-dimensional Ising model in a transverse magnetic field coupled to a dissipative heat bath. The phase diagram and the critical exponents are determined from extensive Monte Carlo simulations. It is shown that the character of the quantum phase transition is radically altered from the corresponding nondissipative model and the double well coupled to a dissipative heat bath with linear friction. Spatial couplings and the dissipative dynamics combine to form a new quantum criticality which is independent of dissipation strength.     

Generation of high-order harmonics of femtosecond radiation from the surface of various media

The results of study of high-order harmonic generation from the surfaces of various materials by using femtosecond radiation with a variable chirp are presented. The analysis and optimization of radiation conversion into harmonics up to the fifteenth order (λ = 52.9 nm) are carried out. It is shown that the maximum conversion efficiency is realized for the surfaces of silver and glass. The wavelength of harmonics can be tuned over the 2-nm range by changing the chirp of the radiation converted.     

A new index of poverty

This paper introduces a new index of poverty. The index satisfies all the axioms for ‘a good index of poverty’.     

Anisotropic cosmological models and generalized scalar tensor theory

In this paper generalized scalar tensor theory has been considered in the background of anisotropic cosmological models, namely, axially symmetric Bianchi-I, Bianchi-III and Kortowski-Sachs space-time. For bulk viscous fluid, both exponential and power-law solutions have been studied and some assumptions among the physical parameters and solutions have been discussed.     

Bacopasides III-V: three new triterpenoid glycosides from Bacopa monniera

Three new saponins, designated as bacopasides III, IV and V have been isolated from Bacopa monniera WETTST. and their structures have been elucidated as 3-O-alpha-L-arabinofuranosyl (1-->2)-beta-D-glucopyranosyl jujubogenin (1), 3-O-beta-D-glucopyranosyl (1-->3)-alpha-L-arabinopyranosyl jujubogenin (2) and 3-O-beta-D-glucopyranosyl (1-->3)-alpha-L-arabinopyranosyl pseudojujubogenin (3) mainly on the basis of two dimensional (2D) NMR and other spectral analyses.     

Supplier Performance and Order Allocation

A supplier's overall performance can be gauged by his unit price and adherence to quality standards and delivery schedules. The cost of substandard quality and non-adherence to delivery schedule is computed and added to the cost of purchase. A set of order quantity and supplier combination is chosen dynamically and the total cost computed to determine the best choice (least total cost).     

A poroelastic spheroidal shell model for studying the problem of head injury

The present investigation is essentially devoted to a study of the cranial biomechanics by modelling the head as a poroelastic spheroidal shell filled with a viscoelastic fluid representing the brain material. Both the skull and the brain are considered as linear and isotropic materials. The problem is formulated in terms of prolate spheroidal coordinates and is treated mathematically by using the integral transform technique. The applicability of the analytical study is illustrated by computing the stress-field generated in the system due to the application of the load through the use of appropriate numerical procedures.