Water Neutral: Reducing and Offsetting the Impacts of Water Footprints

During the past few years the water footprint has started to receive recognition as a useful indicator of water use, within both governments (UNESCO, 2006) and non-governmental organizations (Zygmunt, 2007; WWF, 2008), as well as within businesses (WBCSD, 2006; JPMorgan, 2008) and media (The Independent, 2008; The Economist, 2008; Discover Magazine, 2008). The increased interest in the water-footprint concept has prompted the question about what consumers and businesses can do to reduce their water footprint. Several instruments have been proposed, including a water label for water-intensive products, an international water-pricing protocol, an international business agreement on water-footprint accounting, and a Kyoto-protocol-like agreement on tradable water-footprint permits (Hoekstra, 2006; Verkerk et al., 2008). Another concept that has been proposed is that of 'water neutrality'. The idea behind the concept is to see whether humans can somehow neutralise or offset their 'water footprint'. The question is very general and interesting from the point of view of both individual consumers and larger communities, but also from the perspective of governments and companies. The aim of this report is to critically discuss the water-neutral concept. It first discusses the water-footprint concept, because water neutrality is all about reducing and offsetting the impacts of water footprints (Figure 1.1). Subsequently, the report elaborates the idea of water neutrality. After a generic discussion of the concept, it is discussed what water neutrality means for a product, an individual consumer or a business. Finally, the concept is critically analysed in terms of its strengths and weaknesses

Optical response of highly granular YBaCuO films prepared by non-vacuum aerosol deposition

Highly granular YBaCuO films on SrTiO3 substrates with Tc,o~90K and Jc > 104 A/cm2 were prepared by non-vacuum aerosol deposition. The optical response for these films was investigated on a 10 × 10 μm2 microbridge. Besides a bolometric response around the transition temperature, a sharp response peak was observed at low temperature and high bias current using a He-Ne laser (0.63 μm wavelength) illumination. This response was caused by a junction behaviour due to the presence of many boundary-type weak links in our microbridge

Light Turning Mirrors in SiON Optical Waveguides for Hybrid Integration with CMOS Photo-detectors

A new method is proposed for hybrid integration of SiON optical waveguides and standard CMOS photo-detectors based on anisotropic etching of 45° facets in a Si substrate. After removal of anisotropically etched Si structures in cladding SiO2, the fabricated total-internal-reflection mirrors can direct the output of the waveguides to photo-detectors placed on top of the chip. The metal-free fabrication process, designed to create these mirrors, is convenient for batch production. Fourier optics based simulations predict that the reflection efficiency of the mirrors is 68.5 %. The far field pattern obtained from the fabricated device is similar to the simulated one

Effects of lattice variations on confinement in photonic crystal microcavity using green tensor method

Electric field distribution in and around the 2D PC cavity was calculated for different lattice parameters using the Dyson formulation of the Green tensor. The results demonstrate the sensitive effects of structural variation of the photonic crystal on the effectiveness of field confinement in the cavity

Characterization of optical third-order non-linearities by prism coupling and pulse shape analysis on a ps timescale

Materials with an intensity dependent index of refraction and absorption coefficient¿third-order optical non-linear (ONL) effects¿offer the possibility of all-optical signal processing. Prism coupling is a well-known tool to investigate the intensity dependent refractive index, however, such experiments are often obscured by thermal effects. To avoid these we have studied the influence of the ONL effects on the shape of 70 ps pulses in non-linear prism coupling. The full width at half maximum (FWHM) of the in and out coupled pulses is compared simultaneously with the FWHM of the pulses of a reference beam. By measuring at various angles of incidence around that for optimal coupling it is possible to measure the sign and value of the change in both the refractive index and absorption coefficient. As a function of the coupling angle, the first leads to an asymmetric line shape for the ratio of the two FWHMs mentioned above, whereas the second leads to a symmetric one. From a comparison of simulations with experimental data, the values of the non-linear constants can be derived

An algorithm to detect blends with eclipsing binaries in planet transit searches

We present an algorithm that can detect blends of bright stars with fainter, un-associated eclipsing binaries. Such systems contaminate searches for transiting planets, in particular in crowded fields where blends are common. Spectroscopic follow-up observations on large aperture telescopes have been used to reject these blends, but the results are not always conclusive. Our approach exploits the fact that a blend with a eclipsing binary changes its shape during eclipse. We analyze original imaging data from the Optical Gravitational Lensing Experiment (OGLE), which were used to discover planet transit candidates. Adopting a technique developed in weak gravitational lensing to carefully correct for the point spread function which varies both with time and across the field, we demonstrate that ellipticities can be measured with great accuracy using an ensemble of images. Applied to OGLE-TR-3 and OGLE-TR-56, two of the planetary transit candidates, we show that both systems are blended with fainter stars, as are most other stars in the OGLE fields. Moreover, while we do not detect shape change when TR-56 undergoes transits, TR-3 exhibits a significant shape change during eclipses. We therefore conclude that TR-3 is indeed a blend with an eclipsing binary, as has been suggested from other lines of evidence. The probability that its shape change is caused by residual systematics is found to be less than 0.6%. Our technique incurs no follow-up cost and requires little human interaction. As such it could become part of the data pipeline for any planetary transit search to minimize contamination by blends. We briefly discuss its relevance for the Kepler mission and for binary star detection.Comment: Submitted to ApJ, 10 pages, 10 figure

Lasercooled RaF as a promising candidate to measure molecular parity violation

The parameter $W_\mathrm{a}$, which characterizes nuclear spin-dependent parity violation effects within the effective molecular spin-rotational Hamiltonian, was computed for the electronic ground state of radium fluoride (RaF) and found to be one of the largest absolute values predicted so far. These calculations were performed with the complex generalised Hartree-Fock method within a two-component (quasi-relativistic) zeroth-order regular approximation framework. Peculiarities of the molecular electronic structure of RaF lead to highly diagonal Franck-Condon matrices between vibrational states of the electronic ground and first excited states, which renders the molecule in principle suitable for direct laser cooling. As a trapped gas of cold molecules offers a superior coherence time, RaF can be considered a promising candidate for high-precision spectroscopic experiments aimed at the search of molecular parity-violation effects.Comment: 4.5 pages, 1 figure, 2 tables. Supplementary material can be requested from the authors. Minor changes to version

Going against the flow: A critical analysis of virtual water trade in the context of India's National River Linking Programme

Virtual water trade has been promoted as a tool to address national and regional water scarcity. In the context of international (food) trade, this concept has been applied with a view to optimize the flow of commodities considering the water endowments of nations. The concept states that water-rich countries should produce and export water intensive commodities (which indirectly carry embedded water needed for producing them) to water-scarce countries, thereby enabling the water-scarce countries to divert their precious water resources to alternative, higher productivity uses.\ud While progress has been made on quantifying virtual water flows between countries, there exists little information on virtual water trade within large countries like India. This report quantifies and critically analyzes inter-state virtual water flows in India in the context of a large inter-basin transfer plan of the Government of India.\ud Our analysis shows that the existing pattern of inter-state virtual water trade is exacerbating scarcities in already water scarce states and that rather than being dictated by water endowments, virtual water flows are influenced by other factors such as "per capita gross cropped area" and "access to secured markets". We therefore argue that in order to have a comprehensive understanding of virtual water trade, non-water factors of production need to be taken into consideration