Maxwell's field coupled nonminimally to quadratic torsion: Induced axion field and birefringence of the vacuum

We consider a possible (parity conserving) interaction between the electromagnetic field $F$ and a torsion field $T^\alpha$ of spacetime. For generic elementary torsion, gauge invariant coupling terms of lowest order fall into two classes that are both nonminimal and {\it quadratic} in torsion. These two classes are displayed explicitly. The first class of the type $\sim F T^2$ yields (undesirable) modifications of the Maxwell equations. The second class of the type $\sim F^2 T^2$ doesn't touch the Maxwell equations but rather modifies the constitutive tensor of spacetime. Such a modification can be completely described in the framework of metricfree electrodynamics. We recognize three physical effects generated by the torsion: (i) An axion field that induces an {\em optical activity} into spacetime, (ii) a modification of the light cone structure that yields {\em birefringence} of the vacuum, and (iii) a torsion dependence of the {\em velocity of light.} We study these effects in the background of a Friedmann universe with torsion. {\it File tor17.tex, 02 August 2003}Comment: 6 page

Constraints on spin-dependent short-range interactions using gravitational quantum levels of ultracold neutrons

In this paper, we discuss a possibility to improve constraints on spin-dependent short-range interactions in the range of 1 - 200 micrometer significantly. For such interactions, our constraints are without competition at the moment. They were obtained through the observation of gravitationally bound states of ultracold neutrons. We are going to improve these constraints by about three orders of magnitude in a dedicated experiment with polarized neutrons using the next-generation spectrometer GRANIT.Comment: 5 pages, 4 figures, accepted for publication in the Proceedings of the International Workshop on Particle Physics with Cold Neutrons, Grenoble, May 2008, to be published in Nucl. Instr. and Meth.

Parity-violating macroscopic force between chiral molecules and source mass

A theory concerning non-zero macroscopic chirality-dependent force between a source mass and homochiral molecules due to the exchange of light particles is presented in this paper. This force is proposed to have opposite sign for molecules with opposite chirality. Using the central field approximation, we calculate this force between a copper block and a vessel of chiral molecules (methyl phenyl carbinol nitrite). The magnitude of force is estimated with the published limits of the scalar and pseudo-scalar coupling constants. Based on our theoretical model, this force may violate the equivalence principle when the homochiral molecules are used to be the test masses.Comment: 10 pages, 1 figur

Human Disease/Clinical Medical Sciences in Dentistry: Current state and future development of undergraduate assessments in the UK and Ireland

Introduction The United Kingdom and Ireland teachers of Human Disease/Clinical Medical Science for Dentistry (HD/CMSD) group continues to work together, and most recently collaborated to review current and future assessments. Materials and methods The first part of the review of assessments in HD/CMSD took place at a face‐to‐face meeting with presentations from delegates on assessments in their home institutions. The second, and larger part, comprised an online survey where all eighteen schools in the UK and Ireland participated. Results All schools had some element of formative assessment, and the majority had a stand‐alone summative assessment at the end of the HD/CMSD teaching block. Most schools had a written paper and practical elements to their assessments, most commonly a combination of a multiple‐choice type question combined with an objective structured clinical examination (OSCE). There was a trend towards the use of single best answer (SBA) questions and a willingness among participants to share a question bank. All schools incorporated elements of HD/CMSD in their final examinations. Discussion & Conclusion This collaboration promoted the sharing of developments in assessment for HD/CMSD and demonstrated a willingness to co‐operate between institutions. Assessment in HD/CMSD in the UK and Ireland continues to be refined by those responsible for its content and delivery and assessment methods are progressing following evidence‐based best practice

The next detectors for gravitational wave astronomy

This paper focuses on the next detectors for gravitational wave astronomy which will be required after the current ground based detectors have completed their initial observations, and probably achieved the first direct detection of gravitational waves. The next detectors will need to have greater sensitivity, while also enabling the world array of detectors to have improved angular resolution to allow localisation of signal sources. Sect. 1 of this paper begins by reviewing proposals for the next ground based detectors, and presents an analysis of the sensitivity of an 8 km armlength detector, which is proposed as a safe and cost-effective means to attain a 4-fold improvement in sensitivity. The scientific benefits of creating a pair of such detectors in China and Australia is emphasised. Sect. 2 of this paper discusses the high performance suspension systems for test masses that will be an essential component for future detectors, while sect. 3 discusses solutions to the problem of Newtonian noise which arise from fluctuations in gravity gradient forces acting on test masses. Such gravitational perturbations cannot be shielded, and set limits to low frequency sensitivity unless measured and suppressed. Sects. 4 and 5 address critical operational technologies that will be ongoing issues in future detectors. Sect. 4 addresses the design of thermal compensation systems needed in all high optical power interferometers operating at room temperature. Parametric instability control is addressed in sect. 5. Only recently proven to occur in Advanced LIGO, parametric instability phenomenon brings both risks and opportunities for future detectors. The path to future enhancements of detectors will come from quantum measurement technologies. Sect. 6 focuses on the use of optomechanical devices for obtaining enhanced sensitivity, while sect. 7 reviews a range of quantum measurement options

Advances in the Synthesis and Long-Term Protection of Zero-Valent Iron Nanoparticles

Core@shell Fe@Fe3O4 NPs are synthesized via the thermal decomposition of iron pentacarbonyl (Fe(CO)5) in the presence either of oleylamine (OAm) or a mixture of OAm and oleic acid (OA). The heterostructured nanocomposites formed do so by a post-synthetic modification of isolated Fe seeds. This proves the versatility of the coating procedure and represents a significant advantage over previous work with Co seeds owing to the higher magnetic susceptibility, reduced toxicity, and excellent biocompatibility of Fe. Furthermore, the latter system allows the synthetic methodology to be developed from a two-pot scenario where seeds are isolated then coated, to an easier and more efficient direct one-pot scenario. The two-pot method yields proportionately larger cores. However, in both cases, the monodisperse product reveals a carbonaceous interface between the Fe core and oxide shell. Meanwhile for the one-pot synthesis, the OA:OAm ratio influences both the morphology and dispersity of the product. This is interpreted in terms of competing interactions of the ligands with the iron precursor. Superparamagnetism (SPM) is observed, and microscopic studies reveal oxidative stability of the Fe(0) cores achieved by either method for >6 months. It is proposed that the carbonaceous interface is critical to this sustained oxidative stability

Effect of lutein and antioxidant dietary supplementation on contrast sensitivity in age-related macular disease:A randomized controlled trial

Objective: The aim of the study is to determine the effect of lutein combined with vitamin and mineral supplementation on contrast sensitivity in people with age-related macular disease (ARMD). Design: A prospective, 9-month, double-masked randomized controlled trial. Setting: Aston University, Birmingham, UK and a UK optometric clinical practice. Subjects: Age-related maculopathy (ARM) and atrophic age-related macular degeneration (AMD) participants were randomized (using a random number generator) to either placebo (n = 10) or active (n=15) groups. Three of the placebo group and two of the active group dropped out. Interventions: The active group supplemented daily with 6 mg lutein combined with vitamins and minerals. The outcome measure was contrast sensitivity (CS) measured using the Pelli-Robson chart, for which the study had 80% power at the 5% significance level to detect a change of 0.3log units. Results: The CS score increased by 0.07 ± 0.07 and decreased by 0.02 ± 0.18 log units for the placebo and active groups, respectively. The difference between these values is not statistically significant (z = 0.903, P = 0.376). Conclusion: The results suggest that 6 mg of lutein supplementation in combination with other antioxidants is not beneficial for this group. Further work is required to establish optimum dosage levels

Neutron experiments to search for new spin-dependent interactions

The consideration is presented of possible neutron experiments to search for new short-range spin-dependent forces. The spin-dependent nucleon-nucleon interaction between neutron and nuclei may cause different effects: phase shift of a neutron wave in neutron interferometers of different kind, in particular of the Lloyd mirror configuration, neutron spin rotation in the pseudo-magnetic field, and transverse deflection of polarized neutron beam by a slab of substance. Estimates of sensitivity of these experiments are performed.Comment: 10 p., 4 fig, Corrected Fig. 4, 1 Ref. adde