Unethical aspects of homeopathic dentistry

In the last year there has been a great deal of public debate about homeopathy, the system of alternative medicine whose main principles are that like cures like and that potency increases relative to dilution. The House of Commons Select Committee on Science and Technology concluded in November 2009 that there is no evidence base for homeopathy, and agreed with some academic commentators that homeopathy should not be funded by the NHS. While homeopathic doctors and hospitals are quite commonplace, some might be surprised to learn that there are also many homeopathic dentists practising in the UK. This paper examines the statements made by several organisations on behalf of homeopathic dentistry and suggests that they are not entirely ethical and may be in breach of various professional guidelines

A microlensing measurement of the size of the broad emission line region in the lensed QSO 2237+0305

We present spatially resolved spectroscopic images of the gravitationally lensed QSO 2237+0305 taken with the GMOS Integral Field Unit (IFU) on the Gemini North telescope. These observations have the best spatial resolution of any IFU observations of this object to date and include the redshifted CIII] and MgII QSO broad lines. Unlike Mediavilla et al. 1998, we find no evidence for an arc of resolved broad line emission in either the CIII] or MgII lines. We calculate the image flux ratios of both the integrated emission lines and the surrounding continua. The flux ratios of the CIII] and MgII emission lines are consistent with each other but differ substantially from their corresponding continuum flux ratios and the radio/mid-IR flux ratios previously published. We argue that the broad emission line region must be microlensed and the CIII] and MgII emission regions must be approximately the same size and co-located along the line-of-sight. Assuming a simple model for the broad emission line region and the continuum region, we show the size of the CIII] / MgII broad line region is ~0.06 h_{70}^{1/2} pc and the continuum region is <= 0.02 h_{70}^{1/2} pc.Comment: 7 pages, 7 figures. Accepted for publication in MNRA

On the rate of black hole binary mergers in galactic nuclei due to dynamical hardening

We assess the contribution of dynamical hardening by direct three-body scattering interactions to the rate of stellar-mass black hole binary (BHB) mergers in galactic nuclei. We derive an analytic model for the single-binary encounter rate in a nucleus with spherical and disk components hosting a super-massive black hole (SMBH). We determine the total number of encounters $N_{\rm GW}$ needed to harden a BHB to the point that inspiral due to gravitational wave emission occurs before the next three-body scattering event. This is done independently for both the spherical and disk components. Using a Monte Carlo approach, we refine our calculations for $N_{\rm GW}$ to include gravitational wave emission between scattering events. For astrophysically plausible models we find that typically $N_{\rm GW} \lesssim$ 10. We find two separate regimes for the efficient dynamical hardening of BHBs: (1) spherical star clusters with high central densities, low velocity dispersions and no significant Keplerian component; and (2) migration traps in disks around SMBHs lacking any significant spherical stellar component in the vicinity of the migration trap, which is expected due to effective orbital inclination reduction of any spherical population by the disk. We also find a weak correlation between the ratio of the second-order velocity moment to velocity dispersion in galactic nuclei and the rate of BHB mergers, where this ratio is a proxy for the ratio between the rotation- and dispersion-supported components. Because disks enforce planar interactions that are efficient in hardening BHBs, particularly in migration traps, they have high merger rates that can contribute significantly to the rate of BHB mergers detected by the advanced Laser Interferometer Gravitational-Wave Observatory.Comment: 13 pages, 9 figures, accepted for publication in MNRA

Wind speed dependent size-resolved parameterization for the organic mass fraction of sea spray aerosol

For oceans to be a significant source of primary organic aerosol (POA), sea spray aerosol (SSA) must be highly enriched with organics relative to the bulk seawater. We propose that organic enrichment at the air-sea interface, chemical composition of seawater, and the aerosol size are three main parameters controlling the organic mass fraction of sea spray aerosol (OM&lt;sub&gt;SSA&lt;/sub&gt;). To test this hypothesis, we developed a new marine POA emission function based on a conceptual relationship between the organic enrichment at the air-sea interface and surface wind speed. The resulting parameterization is explored using aerosol chemical composition and surface wind speed from Atlantic and Pacific coastal stations, and satellite-derived ocean concentrations of chlorophyll-&lt;i&gt;a&lt;/i&gt;, dissolved organic carbon, and particulate organic carbon. Of all the parameters examined, a multi-variable logistic regression revealed that the combination of 10 m wind speed and surface chlorophyll-&lt;i&gt;a&lt;/i&gt; concentration ([Chl-&lt;i&gt;a&lt;/i&gt;]) are the most consistent predictors of OM&lt;sub&gt;SSA&lt;/sub&gt;. This relationship, combined with the published aerosol size dependence of OM&lt;sub&gt;SSA&lt;/sub&gt;, resulted in a new parameterization for the organic mass fraction of SSA. Global emissions of marine POA are investigated here by applying this newly-developed relationship to existing sea spray emission functions, satellite-derived [Chl-&lt;i&gt;a&lt;/i&gt;], and modeled 10 m winds. Analysis of model simulations shows that global annual submicron marine organic emission associated with sea spray is estimated to be from 2.8 to 5.6 Tg C yr&lt;sup&gt;−1&lt;/sup&gt;. This study provides additional evidence that marine primary organic aerosols are a globally significant source of organics in the atmosphere

Exploring the Connection Between Star Formation and AGN Activity in the Local Universe

We study a combined sample of 264 star-forming, 51 composite, and 73 active galaxies using optical spectra from SDSS and mid-infrared (mid-IR) spectra from the Spitzer Infrared Spectrograph. We examine optical and mid-IR spectroscopic diagnostics that probe the amount of star formation and relative energetic con- tributions from star formation and an active galactic nucleus (AGN). Overall we find good agreement between optical and mid-IR diagnostics. Misclassifications of galaxies based on the SDSS spectra are rare despite the presence of dust obscuration. The luminosity of the [NeII] 12.8 micron emission-line is well correlated with the star formation rate (SFR) measured from the SDSS spectra, and this holds for the star forming, composite, and AGN-dominated systems. AGN show a clear excess of [NeIII] 15.6 micron emission relative to star forming and composite systems. We find good qualitative agreement between various parameters that probe the relative contributions of the AGN and star formation, including: the mid-IR spectral slope, the ratio of the [NeV] 14.3 micron to [NeII] micron 12.8 fluxes, the equivalent widths of the 7.7, 11.3, and 17 micron PAH features, and the optical "D" parameter which measures the distance a source lies from the locus of star forming galaxies in the optical BPT emission-line diagnostic diagram. We also consider the behavior of the three individual PAH features by examining how their flux ratios depend upon the degree of AGN-dominance. We find that the PAH 11.3 micron feature is significantly suppressed in the most AGN-dominated systems

Attrition of material during cutter suction dredging and pipeline transport: a summary

In the dredging industry, it is advantageous to have advanced knowledge of the expected particle size distribution (PSD) of material that has been subject to dredging processes. During dredging, the removal and transportation of material result in it undergoing significant physical changes. This paper first considers geotechnical, hydraulic and mechanical processes that influence the PSD of a material dredged by cutter suction dredger (CSD), and discusses the attrition during hydraulic transport through pipelines and pumps. When cutting in-situ material, the failure mechanism for intact material varies with material type e.g. for rock cutting the ductility / brittleness of the material is key. During hydraulic transport, particle behaviour and attrition varies primarily according to particle size, from fines undergoing sustained suspension as a dense carrier-fluid to the rolling bed of rock chips or clay balls. To some degree, the attrition follows a decay behaviour (by mass lost) and reduces the solids-effect, and it is generally most prevalent in centrifugal pumps where the destructive forces are greatest. The second part of the paper discusses existing laboratory tests and their ability to simulate processes of attrition. Promising tests fall into three categories: cutterhead scale-models (for simulating material cutting and entrainment into the suction pipe); drum tests (for simulating pipeline attrition); and centrifugal pipeline-loop tests (for reproducing hydraulic pipeline transport). No single laboratory test provides a comprehensive approach to replicating attrition of material undergoing dredging, though each category of test showed unique advantages and disadvantages when considering practicality, scaling and process similitude

In-situ optical characterisation of the spatial dynamics of liquid crystalline nanocomposites

Liquid crystalline nanocomposites are a novel class of hybrid fluid materials, which are currently attracting significant interest from the photonics community. Such fluid nano-composites are based on low-dimensional nanoparticles (carbon nanotubes, graphene, transition metal dichalcogenides (TMDCs), metal nanoparticles etc.) dispersed in a fluidic host material. Liquid crystalline properties can either be provided by using a liquid crystal host fluid, or, through the solvent-induced self-assembly of particles. They possess a unique capability to interact with light, utilising many possibilities in plasmonics and quantum optics while they can also be integrated on Si chip by means of microfluidic technology. Integration of the nanocomposites on chip allows for dynamic control of the dispersed particle ordering through the application of various external stimuli. However, this dynamic control requires a suitable characterisation technique to fully understand the time evolution of metastructure formation. Integrated nanocomposites are characterised by the particle concentration at different points on chip, while the individual particles are defined by their sizes, xyz positions and orientation relative to the chip architecture. Here, we present a method by which all the required information for complete characterisation of the system can be obtained using a single spectroscopic technique- Raman spectroscopy- and how changes in the system can then be monitored during device operation. Liquid crystalline nanocomposites have been synthesised based on two-dimensional (2D) materials including graphene oxide (GO) and TMDCs dispersed in either commercially available liquid crystals or various organic solvents. We present both numerical analysis of the theoretical practicability of the use of Raman spectroscopy to extrapolate the desired nanocomposite properties and the experimental confirmation of the achievability of these measurements for the full range of synthesised nanocomposites

Model evaluation of marine primary organic aerosol emission schemes

In this study, several marine primary organic aerosol (POA) emission schemes have been evaluated using the GEOS-Chem chemical transport model in order to provide guidance for their implementation in air quality and climate models. These emission schemes, based on varying dependencies of chlorophyll &lt;i&gt;a&lt;/i&gt; concentration ([chl &lt;i&gt;a&lt;/i&gt;]) and 10 m wind speed (&lt;i&gt;U&lt;/i&gt;&lt;sub&gt;10&lt;/sub&gt;), have large differences in their magnitude, spatial distribution, and seasonality. Model comparison with weekly and monthly mean values of the organic aerosol mass concentration at two coastal sites shows that the source function exclusively related to [chl &lt;i&gt;a&lt;/i&gt;] does a better job replicating surface observations. Sensitivity simulations in which the negative &lt;i&gt;U&lt;/i&gt;&lt;sub&gt;10&lt;/sub&gt; and positive [chl &lt;i&gt;a&lt;/i&gt;] dependence of the organic mass fraction of sea spray aerosol are enhanced show improved prediction of the seasonality of the marine POA concentrations. A top-down estimate of submicron marine POA emissions based on the parameterization that compares best to the observed weekly and monthly mean values of marine organic aerosol surface concentrations has a global average emission rate of 6.3 Tg yr&lt;sup&gt;−1&lt;/sup&gt;. Evaluation of existing marine POA source functions against a case study during which marine POA contributed the major fraction of submicron aerosol mass shows that none of the existing parameterizations are able to reproduce the hourly-averaged observations. Our calculations suggest that in order to capture episodic events and short-term variability in submicron marine POA concentration over the ocean, new source functions need to be developed that are grounded in the physical processes unique to the organic fraction of sea spray aerosol

Coastal iodine emissions: part 2. Chamber experiments of particle formation from Laminaria digitata-derived and laboratory-generated I2

Laboratory studies into particle formation from Laminaria digitata macroalgae were undertaken to elucidate aerosol formation for a range of I2 (0.3−76 ppbv) and O3(<3−96 ppbv) mixing ratios and light levels (EPAR = 15, 100,and 235 μmol photons m−2 s−1). No clear pattern was observed for I2 or aerosol parameters as a function of light levels. Aerosol mass fluxes and particle number concentrations,were, however, correlated with I2 mixing ratios for low O3mixing ratios of <3 ppbv (R2 = 0.7 and 0.83, respectively for low light levels, and R2 = 0.95 and 0.98, respectively for medium lightlevels). Additional experiments into particle production as a function of laboratory-generated I2, over a mixing ratio range of 1−8ppbv, were conducted under moderate O3 mixing ratios (∼24 ppbv) where a clear, 100-fold or greater, increase in the aeroso lnumber concentrations and mass fluxes was observed compared to the low O3 experiments. A linear relationship between particle concentration and I2 was found, in reasonable agreement with previous studies. Scaling the laboratory relationship to aerosol concentrations typical of the coastal boundary layer suggests a I2 mixing ratio range of 6−93 pptv can account for the observed particle production events. Aerosol number concentration produced from I2 is more than a factor of 10 higher than thatproduced from CH2I2 for the same mixing ratios