Second order splitting of a class of fourth order PDEs with point constraints

We formulate a well-posedness and approximation theory for a class of generalised saddle point problems with a specific form of constraints. In this way we develop an approach to a class of fourth order elliptic partial differential equations with point constraints using the idea of splitting into coupled second order equations. An approach is formulated using a penalty method to impose the constraints. Our main motivation is to treat certain fourth order equations involving the biharmonic operator and point Dirichlet constraints for example arising in the modelling of biomembranes on curved and flat surfaces but the approach may be applied more generally. The theory for well-posedness and approximation is presented in an abstract setting. Several examples are described together with some numerical experiments

Release of bacterial spores from inner walls of a stainless steel cup subjected to thermal stress

In an earlier report thermal stresses, simulating those expected on a Mars Lander, dislodged approximately 0.01% of an aerosol deposited surface burden, as did a landing shock of 8-10 G deceleration. This work confirms earlier results and demonstrates that release rate is not dependent on surface burden

Fermion Mass Hierarchy from the Soft Wall

We develop a 5d model for ElectroWeak physics based on a non compact warped extra dimension of finite length, known as the soft wall scenario, where all the dynamical degrees of freedom propagate in the 5d bulk. We solve the equations of motion and find the allowed spectra, showing that the mass of the lightest fermionic mode behaves as a power law of the effective 4d Yukawa coupling constant, with the exponent being the corresponding fermionic 5d bulk mass. Precisely this non universal behavior allows us to reproduce the hierarchy between the Standard Model (SM) fermion masses (from neutrinos to the top quark) with non-hierarchical fermionic bulk masses.Comment: 26 pages, 4 figures, minor changes, one figured added, version to be publish in PR

Infectious intestinal disease : do we know it all?

Infectious intestinal disease (IID), with associated high morbidity and considerable mortality worldwide, causes a wide spectrum of illness. This ranges from mild discomfort to illness with severe complications. The economic burden from direct and indirect costs may be high. It is acquired by oral ingestion of micro-organisms which are transmitted from person to person; via food or water or through contact with animals or contaminated objects. Viruses are the commonest cause in developed countries. In Malta, medical practitioners and laboratories are the main source of data on IID. However, under-reporting is a problem. In order to fill in the lacunae in information on the disease burden, population-based-studies are required. Along with other countries, Malta has embarked on a number of studies to describe and quantify under-reporting of IID. This may assist in strengthening the surveillance system which, in combination with other measures, should result in an improvement of the control of IID.peer-reviewe

Laboratory surveillance of communicable diseases : enteric pathogens

Laboratories represent a crucial link in the surveillance chain. Since only a small proportion of cases of enteric infections are asked to submit a stool sample, one needs to assess the practices for testing for enteric pathogens and their notification practices. Five local laboratories participated in this study. This included a description of the laboratory practices; capacity for stool sample analysis; awareness of the notification system and the factors which could improve the system at laboratory level.peer-reviewe

Wing flutter calculations with the CAP-TSD unsteady transonic small disturbance program

The application and assessment is described of CAP-TSD (Computational Aeroelasticity Program - Transonic Small Disturbance) code for flutter prediction. The CAP-TSD program was developed for aeroelastic analysis of complete aircraft configurations and was previously applied to the calculation of steady and unsteady pressures. Flutter calculations are presented for two thin, swept-and-tapered wing planforms with well defined modal properties. The calculations are for Mach numbers from low subsonic to low supersonic values, including the transonic range, and are compared with subsonic linear theory and experimental flutter data. The CAP-TSD flutter results are generally in good agreement with the experimental values and are in good agreement with subsonic linear theory when wing thickness is neglected

Submillimeter-Wave Measurements and Analysis of the Ground and ν2 = 1 States of Water

In order to facilitate further studies of water in the interstellar medium, the envelopes of late-type stars, jets, and shocked regions, the frequencies of 17 newly measured H_2 ^(16)O transitions between 0.841 and 1.575 THz are reported. A complete update of the available water line frequencies and a detailed calculation of unmeasured rotational transitions and transition intensities as a function of temperature are presented for the ground and ν_2 = 1 state levels below 3000 cm^(-1) of excitation energy. The new terahertz transitions were measured with a recently developed laser difference frequency spectrometer. Six of these transitions arise from the ν_2 = 1 state, and the other 11 are in the ground state; all have lower state energies from 700 to 1750 cm^(-1) and should be accessible to Stratospheric Observatory For Infrared Astronomy (SOFIA) through the atmosphere. The transitions near 0.850 THz are accessible from the ground with existing receivers. Observations of the newly measured ν_2 = 1 state transitions, which include the 1_(1, 1)-0_(0, 0) fundamental at 1.2057 THz and five other very low J transitions, should provide valuable insights into role played by the ν2 = 1 state in the cooling dynamics of jets, shocks, masers, and strongly infrared-pumped regions. The line list is presented to assist in the planning of observational campaigns with the Far-Infrared Space Telescope (FIRST) and other proposed space missions with which a full suite of water observations can be carried out

A High Power Frequency-Stabilized Tunable Two-Frequency Diode Laser System for the Generation of Coherent THz-Waves by Photomixing

A tunable two-frequency high-power diode laser system at 850 nm for terahertz (Thz)-wave generation by photomixing in low-temperature-grown GaAs photo-conductors has been developed. The difference frequency is obtained through a three laser system, where two lasers are locked to different orders of a Fabry-Perot cavity and a third is offset-locked to the first, The difference-frequency signal is generated by the offset laser and the other cavity-locked laser. The spectral purity of the beat note is better than 1 MHz. The maximum output power of -500 mW was obtained by using the master oscillator power amplifier (MOPA) technique, simultaneous injection of two seed frequencies with a single semiconductor optical amplifier. Here we report the generation of THz waves and spectroscopy of acetonitrile as proof of concept

Use of entanglement in quantum optics

Several recent demonstrations of two-particle interferometry are reviewed and shown to be examples of either color entanglement or beam entanglement. A device, called a number filter, is described and shown to be of value in preparing beam entanglements. Finally, we note that all three concepts (color and beam entaglement, and number filtering) may be extended to three or more particles