The Development of New Concepts for Assessing Reproductive Toxicity Applicable to Large Scale Toxicological Programmes

Large scale toxicological testing programmes which are currently ongoing such as the new European chemical legislation REACH require the development of new integrated testing strategies rather than applying traditional testing schemes to thousands of chemicals. The current practice of requiring in vivo testing for every possible adverse effect endanger the success of these programmes due (i) to limited testing facilities and sufficient capacity of scientific/technical knowledge for reproductive toxicity; (ii) an unacceptable number of laboratory animals involved (iii) an intolerable number of chemicals classified as false positive. A key aspect of the implementation of new testing strategies is the determination of prevalence of reproductive toxicity in the universe of industrial chemicals. Prevalences are relevant in order to be aware on the expected rate of false classification during the toxicological testing and to implement appropriate measures for their avoidance. Furthermore, a detailed understanding on the subendpoints affected by reproductive toxicants and the underlying mechanisms will lead to more science based testing strategies integrating alternative methods without compromising the protection of consumers

SPUTTER DEPTH PROFILING OF OPTICAL WAVEGUIDES USING SECONDARY ION MASS SPECTROMETRY

The technique of sputter depth profiling by means of secondary ion mass spectrometry of samples with high resistivity is reviewed. As examples we discuss optical waveguides made in lithium niobate by titanium indiffusion and implantation and also yttrium iron garnet waveguides grown by liquid phase epitaxy on gadolinium gallium garnet. Depth profiling of these waveguide structures has been performed and the necessary precautions to prevent charging by the primary ion beam are discussed. In some cases, coating with a metallic layer is adequate, but a more universal method is charge neutralization by an additional electron beam

No asymmetric outflows from Sagittarius A* during the pericenter passage of the gas cloud G2

The gas cloud G2 falling toward Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, is supposed to provide valuable information on the physics of accretion flows and the environment of the black hole. We observed Sgr A* with four European stations of the Global Millimeter Very Long Baseline Interferometry Array (GMVA) at 86 GHz on 1 October 2013 when parts of G2 had already passed the pericenter. We searched for possible transient asymmetric structure -- such as jets or winds from hot accretion flows -- around Sgr A* caused by accretion of material from G2. The interferometric closure phases remained zero within errors during the observation time. We thus conclude that Sgr A* did not show significant asymmetric (in the observer frame) outflows in late 2013. Using simulations, we constrain the size of the outflows that we could have missed to ~2.5 mas along the major axis, ~0.4 mas along the minor axis of the beam, corresponding to approximately 232 and 35 Schwarzschild radii, respectively; we thus probe spatial scales on which the jets of radio galaxies are suspected to convert magnetic into kinetic energy. As probably less than 0.2 Jy of the flux from Sgr A* can be attributed to accretion from G2, one finds an effective accretion rate eta*Mdot < 1.5*10^9 kg/s ~ 7.7*10^-9 Mearth/yr for material from G2. Exploiting the kinetic jet power--accretion power relation of radio galaxies, one finds that the rate of accretion of matter that ends up in jets is limited to Mdot < 10^17 kg/s ~ 0.5 Mearth/yr, less than about 20% of the mass of G2. Accordingly, G2 appears to be largely stable against loss of angular momentum and subsequent (partial) accretion at least on time scales < 1 year.Comment: 5 pages, 2 figures, 1 table; A&A Letter, in press (submitted 2015 February 26; accepted 2015 March 31

Compact Tm-doped fibre laser pumped by a 1600 nm Er-doped fibre laser designed for environmental gas sensing

In this work, the compact all-fibre linear Erbium (Er)-doped fibre lasers, operating at wavelengths of 1584 nm and 1600 nm have been described and optimized, with an aim to achieve better pumping conditions for a Thulium (Tm)-doped fibre laser. Optimization of the system has been carried out involving the studies on the different lengths of the Er-doped fibre and the different grating pairs used to achieve 173.5 mW of laser power at 1600 nm under bidirectional pumping at 980 nm. The designed Er-doped fibre laser at 1600 nm has been utilized successfully to pump longer wavelength Tm-doped fibre laser. The obtained laser power (output of Tm-doped fibre laser) of 35.5 mW at 1874 nm and 10.6 mW at 1995 nm is effective for environmental gas sensing, as these wavelengths align well with the absorption spectra of greenhouse gases such as CO2. The laser offers high power (tens of milliWatts), good directionality and a compact overall packaging with the diode pumping, making them ideally suited to ‘in-the-field’ use

5 year Global 3-mm VLBI survey of Gamma-ray active blazars

The Global mm-VLBI Array (GMVA) is a network of 14 3\,mm and 7\,mm capable telescopes spanning Europe and the United States, with planned extensions to Asia. The array is capable of sensitive maps with angular resolution often exceeding 50\,$\mu$as. Using the GMVA, a large sample of prominent $\gamma$-ray blazars have been observed approximately 6 monthly from later 2008 until now. Combining 3\,mm maps from the GMVA with near-in-time 7\,mm maps from the VLBA-BU-BLAZAR program and 2\,cm maps from the MOJAVE program, we determine the sub-pc morphology and high frequency spectral structure of $\gamma$-ray blazars. The magnetic field strength can be estimated at different locations along the jet under the assumption of equipartition between magnetic field and relativistic particle energies. Making assumptions on the jet magnetic field configuration (e.g. poloidal or toroidal), we can estimate the separation of the mm-wave "core" and the jet base, and estimate the strength of the magnetic field there. The results of this analysis show that on average, the magnetic field strength decreases with a power-law $B \propto r^{-n}$, $n=0.3 \pm 0.2$. This suggests that on average, the mm-wave "core" is $\sim 1-3$\,pc downstream of the de-projected jet apex and that the magnetic field strength is of the order $B_{\rm{apex}} \sim 5-20$\,kG, broadly consistent with the predictions of magnetic jet launching (e.g. via magnetically arrested disks (MAD)).Comment: 6 pages, 1 figur

"All-fiber" tunable laser in the 2 mu m region, designed for CO2 detection

A stable and tunable thulium-doped “all-fiber” laser offering a narrow linewidth has been created specifically to act as a compact and simple laser source for gaseous CO2 detection. This has been done through a careful design to match the laser output wavelengths to the CO2 absorption lines at 1.875 and 1.997 μm, respectively. A sustainable output power of 11 mW over a tuning range of 7 nm has been obtained by using a combination of a high-reflective fiber Bragg grating with a low-reflective broadband mirror, fabricated at the end of the fiber through silver film deposition. The tuning was achieved using the relaxation-compression mechanism of the fiber Bragg grating, which formed an integral part of the laser resonant cavity. A fiber Bragg grating at 1.548 μm was utilized as a wavelength reference to monitor the tuning of the laser output over the 2 μm wavelength range with a simple and inexpensive interrogator, to avoid the use of an expensive optical spectrum analyzer and to facilitate “in-the-field” operation. This “all-fiber” laser resonator has been shown to be superior in terms of laser tuning range, output power, and linewidth compared to that created with a fiber Bragg grating pair, which was limited by the nonuniform strain transfer to both fiber Bragg gratings

Fibre optic humidity sensor designed for highly alkaline environments

This paper presents the design of a sensor packaging for a Fibre Bragg Grating (FBG) based fibre optic humidity sensor. The evaluation of the developed fibre optic sensor was performed under experimental conditions and verified its capability to withstand highly alkaline environments. Therefore, the sensor can be applied to monitor the concrete humidity level and thus to indicate the maintenance of concrete structures

ISO observations of a sample of Compact Steep Spectrum and GHz Peaked Spectrum Radio Galaxies

We present results from observations obtained with ISOPHOT, on board the ISO satellite, of a representative sample of seventeen CSS/GPS radio galaxies and of a control sample of sixteen extended radio galaxies spanning similar ranges in redshift (0.2 = 10^26 W/Hz). The observations have been performed at lambda = 60, 90, 174 and 200 microns. Seven of the CSS/GPS sources have detections >= 3 sigma at one or more wavelengths, one of which is detected at >= 5 sigma. By co-adding the data we have obtained average flux densities at the four wavelengths. We found no evidence that the FIR luminosities of the CSS/GPS sources are significantly different from those of the extended objects and therefore there is not any support for CSS/GPS sources being objects "frustrated" by an abnormally dense ambient medium. The two samples were then combined, providing FIR information on a new sample of radio galaxies at intermediate redshifts. We compare this information with what previously known from IRAS and discuss the average properties of radio galaxies in the redshift range 0.2 - 0.8. The FIR emission cannot be accounted for by extrapolation of the synchrotron radio spectrum and we attribute it to thermal dust emission. The average FIR luminosity is >= 6*10^11 L_sun. Over the observed frequency range the infrared spectrum can be described by a power law with spectral index alpha >~1.0 +/- 0.2. Assuming the emission to be due to dust, a range of temperatures is required, from >=80 K to \~25 K. The dust masses required to explain the FIR emission range from 5*10^5 M_sun for the hotter component up to 2*10^8 M_sun for the colder one. (abridged)Comment: Astronomy & Astrophysics, in press, 16 pages, 2 Figure