Casimir Effect In Krein Space Quantization

An explicit calculation of Casimir effect through an alternative approach of field quantization [1, 2], has been presented in this paper. In this method, the auxiliary negative norm states have been utilized, the modes of which do not interact with the physical states or real physical world. Naturally these modes cannot be affected by the physical boundary conditions. Presence of negative norm states play the rule of an automatic renormalization device for the theory.Comment: 7 pages, LaTe

Genetic manipulation of fungal strains for the improvement of heterologous genes expression (a mini-review)

Fungi are eukaryotic microorganisms that influence our everyday lives in areas as diverse as agriculture, medicine and basic science. With the advent of molecular biology, it has been attempted to improve the expression level of heterologous genes, which encode favorable traits in fungal strains. The expression of heterologous genes can be limited in transcription, post-transcription, translation and post-translation levels. Several genetic strategies have been developed to reduce the expression constrains and to enhance genes functionality. Among these strategies can be pointed to the introduction of multicopies of the desired gene, change of AT-rich sequences, gene fusion with a wellexpressed gene, the use of strong promoters and signal sequences, optimization of codon usage, the construction and use of protease-deficient and chaperones/foldases-overproduced strains and the use of native or artificial intron-containing genes. These strategies have often resulted in the expected increase in the expression of heterologus genes. With the isolation of a large number of genes encoding desired traits and the availability of a large collection of wild isolates, the improvement of strains with a better functional performance would be possible.Key words: Strain improvement, gene, heterologous, intron, promoter, codon

Knee Implant Loosening Detection: A Vibration Analysis Investigation.

Knee implant loosening is mainly caused by the weakness of the prosthesis-bone interface and is the main reason for surgical revisions. However, pre-operative diagnosis is difficult due to lack of accurate tests. In this study, we developed a vibration-based system to detect the loosening of the tibial implant of an instrumented knee prosthesis. The proposed system includes an instrumented vibrator for transcutaneous stimulation of the bone in a repeatable manner, and accelerometer sensors integrated into the implants to measure the propagated vibration. A coherence-based detection technique was proposed to distinguish the loosened implants from the secure ones. Fourteen ex vivo lower limbs were used, on which the knee prosthesis was implanted, and harmonic-forced vibration was applied on the tibia. The input-output coherence measure provided 92.26% accuracy, a high sensitivity (91.67%) and specificity (92.86%). This technique was benchmarked against power spectrum based analysis of the propagated vibration to the implant. In particular, loosening detection based on new peak appearance, peak shift, and peak flattening in power spectra showed inferior performance to the proposed coherence-based technique. As such, application of vibration on our instrumented knee prosthesis together with input-output coherence analysis enabled us to distinguish the secure from loose implants

Power Spectrum in Krein Space Quantization

The power spectrum of scalar field and space-time metric perturbations produced in the process of inflation of universe, have been presented in this paper by an alternative approach to field quantization namely, Krein space quantization [1,2]. Auxiliary negative norm states, the modes of which do not interact with the physical world, have been utilized in this method. Presence of negative norm states play the role of an automatic renormalization device for the theory.Comment: 8 pages, appear in Int. J. Theor. Phy

Dust-Charge Variation Effects on Dust ion Acoustic Shock Waves in Four Component Quantum Plasma

The behavior of nonlinear quantum dust ion acoustic (QDIA) shock waves in a collisionless, unmagnetized plasma consisting of inertialess quantum electrons and positrons, classical cold ions and stationary negatively charged dust grains with dust charge variation is investigated using quantum hydrodynamic (QHD) equations. The propagation of small amplitude QDIA shock waves is governed by Burgers equation. It is shown that the dust charge variation plays an important role in the formation of such QDIA shock structures. The dependence of the shock waves amplitude and thickness on the chemical potential is investigated. The present theory is applicable to analyze the formation of nonlinear structures at quantum scales in dense astrophysical objects

Social welfare analysis of investment public-private partnership approaches for tansportation projects

This paper has two objectives: (1) to introduce a new approach to gaining widespread support for comprehensive road pricing; and (2) to develop a detailed social welfare analysis for road pricing schemes. We first describe a new approach to garnering support for system-wide road pricing, which we refer to as an investment public-private partnership, or IP3. This approach returns a significant portion of the economic value created by road pricing back to its citizen-owners. Next, we present a social welfare framework that estimates the benefits and costs of using the IP3 approach on an urban transportation network. Policy makers typically evaluate public-private partnership (P3) projects using Value for Money (VfM) analysis. However, a P3 project's impact on overall social welfare provides a more comprehensive evaluation criterion. Apart from several theoretical studies, a detailed social welfare analysis that includes all major P3 project stakeholders is lacking. Using Fresno City's transportation system as our case study, we show that system-optimal tolling scenarios favor average users, but that government¿and consequently taxpayers¿would pay for costly tolling systems. In contrast, unlimited profit-maximizing tolls raise substantial profits for government, for the infrastructure's citizen-owners, and for the private sector, but the average user is worse off. From a social welfare perspective, one should search for a Pareto-improvement under which all major stakeholders are better off. Our estimates indicate that a mixed private and public tolling scheme offers such an improvement. A mixed scheme results in the highest social welfare among all scenarios unless the weight placed on motorists' (i.e., transportation users') welfare is very low or the weight placed on residents' welfare is very high relative to the weight of other stakeholders

Dual phononic and photonic band gaps in a periodic array of pillars deposited on a thin plate

We study theoretically the simultaneous existence of phononic and photonic band gaps in a periodic array of silicon pillars deposited on a homogeneous thin silica plate. Several lattices, namely, square, triangular, and honeycomb are investigated for a wide range of geometrical parameters. We discuss the most suitable cases for dual phononic-photonic band gaps, especially in comparison to the more conventional structures constituted by a periodic array of holes in a membrane

Watersheds are Schramm-Loewner Evolution curves

We show that in the continuum limit watersheds dividing drainage basins are Schramm-Loewner Evolution (SLE) curves, being described by one single parameter $\kappa$. Several numerical evaluations are applied to ascertain this. All calculations are consistent with SLE$_\kappa$, with $\kappa=1.734\pm0.005$, being the only known physical example of an SLE with $\kappa<2$. This lies outside the well-known duality conjecture, bringing up new questions regarding the existence and reversibility of dual models. Furthermore it constitutes a strong indication for conformal invariance in random landscapes and suggests that watersheds likely correspond to a logarithmic Conformal Field Theory (CFT) with central charge $c\approx-7/2$.Comment: 5 pages and 4 figure