Attenuation in Rectangular Waveguides with Finite Conductivity Walls

We present a fundamental and accurate approach to compute the attenuation of electromagnetic waves propagating in rectangular waveguides with finite conductivity walls. The wavenumbers kx and ky in the x and y directions respectively, are obtained as roots of a set of transcendental equations derived by matching the tangential component of the electric field (E) and the magnetic field (H) at the surface of the waveguide walls. The electrical properties of the wall material are determined by the complex permittivity ε, permeability μ, and conductivity σ. We have examined the validity of our model by carrying out measurements on the loss arising from the fundamental TE10 mode near the cutoff frequency. We also found good agreement between our results and those obtained by others including Papadopoulos’ perturbation method across a wide range of frequencies, in particular in the vicinity of cutoff. In the presence of degenerate modes however, our method gives higher losses, which we attribute to the coupling between modes as a result of dispersion

Wave Propagation in Lossy and Superconducting Circular Waveguides

We present an accurate approach to compute the attenuation of waves, propagating in circular waveguides with lossy and superconducting walls. A set of transcendental equation is developed by matching the fields at the surface of the wall with the electrical properties of the wall material. The propagation constant kz is found by numerically solving for the root of the equation. The complex conductivity of the superconductor is obtained from the Mattis-Bardeen equations. We have compared the loss of TE11 mode computed using our technique with that using the perturbation and Stratton’s methods. The results from the three methods agree very well at a reasonable range of frequencies above the cutoff. The curves, however, deviate below cutoff and at millimeter wave frequencies. We attribute the discrepancies to the dispersive effect and the presence of the longitudinal fields in a lossy waveguide. At frequencies below the gap, the superconducting waveguide exhibits lossless transmission behavior. Above the gap frequency, Cooper-pair breaking becomes dominant and the loss increases significantly

Experimental Demonstration of Quantum Fully Homomorphic Encryption with Application in a Two-Party Secure Protocol

A fully homomorphic encryption system hides data from unauthorized parties while still allowing them to perform computations on the encrypted data. Aside from the straightforward benefit of allowing users to delegate computations to a more powerful server without revealing their inputs, a fully homomorphic cryptosystem can be used as a building block in the construction of a number of cryptographic functionalities. Designing such a scheme remained an open problem until 2009, decades after the idea was first conceived, and the past few years have seen the generalization of this functionality to the world of quantum machines. Quantum schemes prior to the one implemented here were able to replicate some features in particular use cases often associated with homomorphic encryption but lacked other crucial properties, for example, relying on continual interaction to perform a computation or leaking information about the encrypted data. We present the first experimental realization of a quantum fully homomorphic encryption scheme. To demonstrate the versatility of a a quantum fully homomorphic encryption scheme, we further present a toy two-party secure computation task enabled by our scheme

Experimental Demonstration of Quantum Fully Homomorphic Encryption with Application in a Two-Party Secure Protocol

A fully homomorphic encryption system hides data from unauthorized parties, while still allowing them to perform computations on the encrypted data. Aside from the straightforward benefit of allowing users to delegate computations to a more powerful server without revealing their inputs, a fully homomorphic cryptosystem can be used as a building block in the construction of a number of cryptographic functionalities. Designing such a scheme remained an open problem until 2009, decades after the idea was first conceived, and the past few years have seen the generalization of this functionality to the world of quantum machines. Quantum schemes prior to the one implemented here were able to replicate some features in particular use-cases often associated with homomorphic encryption but lacked other crucial properties, for example, relying on continual interaction to perform a computation or leaking information about the encrypted data. We present the first experimental realisation of a quantum fully homomorphic encryption scheme. We further present a toy two-party secure computation task enabled by our scheme. Finally, as part of our implementation, we also demonstrate a post-selective two-qubit linear optical controlled-phase gate with a much higher post-selection success probability (1/2) when compared to alternate implementations, e.g. with post-selective controlled-$Z$ or controlled-$X$ gates (1/9).Comment: 11 pages, 16 figures, 2 table

Effects of inter-particle friction on the critical state behaviour of granular materials: a numerical study

The Conference program's website is located at http://congress.cimne.com/particles2013/frontal/ProgTodo.aspTechnical Session: IS - Instability Mechanisms: From Particles to Structures II (Invited Session)ECCOMAS Thematic Conference SeriesCritical state soil mechanics (CSSM) gives a theoretical framework for soil modelling. This paper investigates the effect of inter-particle friction on the critical state behavior of DEM assemblies with grading representative of a real soil. It is found that the angle of shearing resistance at the critical state increases with increasing inter-particle friction () and in void ratio (e) vs logarithmic mean effective stress (log(p’)) space the critical state locii have higher e values when is higher. An atypical CSL in e-logp’ space that deviates from experimental observations and the classical CSSM behavior was observed when µ = 0.5. Micro-scale analyses show that this can be attributed to the emergence of a higher number of floating particles due to the increasing self-stability of strong force chains with increasing inter-particle friction. This study recommends the use of inter-particle friction lower than 0.5 in DEM simulations of element testing in soil mechanics.published_or_final_versio

Effects of inter-particle friction on the critical state behavior of granular materials: a numerical study

Critical state soil mechanics (CSSM) gives a theoretical framework for soil modelling. This paper investigates the effect of inter-particle friction on the critical state behavior of DEM assemblies with grading representative of a real soil. It is found that the angle of shearing resistance at the critical state increases with increasing inter-particle friction (µ) and in void ratio (e) vs logarithmic mean effective stress (log(p’)) space the critical state locii have higher e values when µ is higher. An atypical CSL in e-logp’ space that deviates from experimental observations and the classical CSSM behavior was observed when µ = 0.5. Micro-scale analyses show that this can be attributed to the emergence of a higher number of floating particles due to the increasing self-stability of strong force chains with increasing inter-particle friction. This study recommends the use of inter-particle friction lower than 0.5 in DEM simulations of element testing in soil mechanics

Regulation of Homologous Recombination between Divergent DNA Sequences by Mismatch Repair Proteins

__Abstract__ Genomes of living organisms, from unicellular bacteria to multicellular human, are threatened by a plethora of DNA lesions. It is estimated that there are ~100,000 DNA lesions inflicted in a single cell on a daily basis (Lindahl, 1993). Both endogenous and exogenous agents induce the formation of these lesions in the genome. Internally, other than replication errors that generate DNA mismatches, reactive oxygen species, alkylating agents and spontaneous hydrolysis damage DNA. These structural alterations include oxidation, methylation, deamination, depurination and depyrimidation of DNA bases. External agents such as ultraviolet radiation, high-frequency radiations like X-rays and γ-rays, natural and synthetic toxins, can all damage DNA by changing its structure. These agents mediate the formation of intra- and interstrand crosslinks, of bulky adducts as well as of single- and double-strand breaks (DSBs) in the DNA. To ensure proper operation of DNA transactions, which are important for cellular survival, a variety of DNA-repair pathways act on these DNA lesions to preserve the integrity of the genome (Hoeijmakers 2001, 2009; Friedberg 2003; Garinis et al., 2008). These DNArepair pathways include DNA mismatch repair (MMR; Jiricny 2013), base excision repair (BER; Goosen and Moolenaar, 2008), nucleotide excision repair (NER; Goosen and Moolenaar, 2008), non-homologous end joining (NHEJ; Shuman and Glickman,

Transmission electron microscopical studies of the layered structure of the ternary semiconductor CuIn₅Se₈

The structure of the off-stoichiometric In-rich ternary phase CuIn5Se8 was studied by means of electron diffraction and high-resolution electron microscopy. The compound shows a layered structure with a 7-layer stacking sequence of closed-packed planes, which contains both cubic and hexagonal stacking of Se atoms. The studied CuIn5Se8 bulk crystal is known as the b-phase of this compound

Randomised controlled trial of ranitidine versus omeprazole in combination with antibiotics for eradication of Helicobacter pylori.

This study compared high dose ranitidine versus low dose omeprazole with antibiotics for the eradication of H pylori. 80 patients (mean age 48 years, range 18-75) who had H pylori infection were randomised in an investigator-blind manner to either a two-week regime of omeprazole 20 mg daily, amoxycillin 500 mg tid and metronidazole 400 mg tid (OAM), or ranitidine 600 mg bd, amoxycillin 500 mg tid and metronidazole 400 mg tid (RAM), or omeprazole 20 mg daily and clarithromycin 500 mg tid (OC), or omeprazole 20 mg daily and placebo (OP). H pylori was eradicated in 6 of 19 patients in the OAM group (32%); 8 of 18 in the RAM group (44%), 4 of 15 in the OC group (27%); none of 18 in the OP group (0%). [< P0.005 for OAM, RAM, OC vs OP; P = N.S. between OAM, RAM, OC]. Overall metronidazole resistance was unexpectedly high at 58%. Eradication rates in metronidazole sensitive patients were 71% (5/7) and 100% (3/3) for OAM and RAM respectively. In conclusion, H pylori eradication rates using high dose ranitidine plus amoxycillin and metronidazole may be similar to that of low dose omeprazole in combination with the same antibiotics for omeprazole with clarithromycin. Overall eradication rates were low due to a high incidence of metronidazole resistance but were higher in metronidazole-sensitive patients. Even high dose ranitidine with two antibiotics achieves a relatively low eradication rate. These metronidazole-based regimens cannot be recommended in areas with a high incidence of metronidazole resistance

A Large Retinal Capillary Hemangioma in the Anterior Retina Treated with Photodynamic Therapy

www.karger.com/cop This is an Open Access article licensed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License (www.karger.com/OA-license), applicable to the online version of the article only. Distribution for non-commercial purposes only