Identification of appropriate temporal scales of dominant low flow indicators in the Main River, Germany

Models incorporating the appropriate temporal scales of dominant indicators for low flows are assumed to perform better than models with arbitrary selected temporal scales. In this paper, we investigate appropriate temporal scales of dominant low flow indicators: precipitation (P), evapotranspiration (ET) and the standardized groundwater storage index (G). This analysis is done in the context of low flow forecasting with a lead time of 14 days in the Main River, a tributary of the Rhine River, located in Germany. Correlation coefficients (i.e. Pearson, Kendall and Spearman) are used to reveal the appropriate temporal scales of dominant low flow indicators at different time lags between low flows and indicators and different support scales of indicators. The results are presented for lag values and support scales, which result in correlation coefficients between low flows and dominant indicators falling into the maximum 10% percentile range. P has a maximum Spearman correlation coefficient (ρ) of 0.38 (p = 0.95) at a support scale of 336 days and a lag of zero days. ET has a maximum ρ of –0.60 (p = 0.95) at a support scale of 280 days and a lag of 56 days and G has a maximum ρ of 0.69 (p = 0.95) at a support scale of 7 days and a lag of 3 days. The identified appropriate support scales and lags can be used for low flow forecasting with a lead time of 14 days

Identification of an appropriate low flow forecast model\ud for the Meuse River

This study investigates the selection of an appropriate low flow forecast model for the Meuse\ud River based on the comparison of output uncertainties of different models. For this purpose, three data\ud driven models have been developed for the Meuse River: a multivariate ARMAX model, a linear regression\ud model and an Artificial Neural Network (ANN) model. The uncertainty in these three models is assumed to\ud be represented by the difference between observed and simulated discharge. The results show that the ANN\ud low flow forecast model with one or two input variables(s) performed slightly better than the other statistical\ud models when forecasting low flows for a lead time of seven days. The approach for the selection of an\ud appropriate low flow forecast model adopted in this study can be used for other lead times and river basins\ud as well

Slow light with flat or offset band edges in multi-mode fiber with two gratings

We consider mode coupling in multimode optical fibers using either two Bragg gratings or a Bragg grating and a long-period grating. We show that the magnitude of the band edge curvature can be controlled leading to a flat, quartic band-edge or to two band edges at distinct, nonequivalent $k$-values, allowing precise control of slow light propagation.Comment: 6 pages, 3 figure

TRYING TO STOP A BLOODY BUSINESS: THE EU´S POLICIES TO CURTAIL THE TRADE IN NATURAL RESOURCES THAT FUND ARMED CONFLICTS

In several of the world’s armed conflicts, natural resources are an important source of income for the warring parties. Cutting this stream of revenues has therefore also become an objective of conflict prevention and –management policies of the European Union (EU). However, in contrast to its usual more multilateral leanings the EU is using in this issue field predominantly unilateral measures. The article therefore seeks to explain this policy choice. By borrowing the Global Production Network (GPN)-conceptualisation from the field of the Economic Geography, the article illustrates how the global context in which the EU acts is becoming increasingly adverse for global measures. Many state actors are hesitant to commit themselves to binding, automatic measures regarding the trade in natural resources. Likewise, European companies, NGOs and consumers are losing leverage on the GPNs of many products that potentially use conflict-financing commodities. This situation decreases the EU’s indirect “market power”. As a result of these developments, the only left policy option for the EU to curb the trade in these conflict resources is imposing unilateral measures. This situation, however, creates certain tensions with its self-image as promoter of “effective multilateralism” in the world

Collective Effects in Nanolasers Explained by Generalized Rate Equations

We study the stationary photon output and statistics of small lasers. Our closed-form expressions clarify the contribution of collective effects due to the interaction between quantum emitters. We generalize laser rate equations and explain photon trapping: a decrease of the photon number output below the lasing threshold, derive an expression for the stationary cavity mode autocorrelation function $g_2$, which implies that collective effects may strongly influence the photon statistics. We identify conditions for coherent, thermal and superthermal radiation, the latter being a unique fingerprint for collective emission in lasers. These generic analytical results agree with recent experiments, complement numerical results, and provide insight into and design rules for nanolasers.Comment: 5 pages, 4 figures, Supplementary materials 4 page

Efficient slow-light coupling in a photonic crystal waveguide without transition region

We consider the coupling into a slow mode that appears near an inflection point in the band structure of a photonic crystal waveguide. Remarkably, the coupling into this slow mode, which has a group index n(g) > 1000, can be essentially perfect without any transition region. We show that this efficient coupling occurs thanks to an evanescent mode in the slow medium, which has appreciable amplitude and helps satisfy the boundary conditions but does not transport any energy. (C) 2008 Optical Society of AmericaPublisher PDFPeer reviewe

Exploring Environmental-Economic Benefits from Agri-Industrial Diversification in the Sugar Industry: An Integrated Land Use and Value Chain Approach

The sugar industry in Queensland (Australia) is confronted with increasing economic pressure and environmental constraints. To explore whether agri-industrial diversification of the sugar industry provides a sustainable development pathway for the region, we develop a spatial environmental-economic approach that integrates a land use and value chain model with a hydrological model. Results indicate that agri-industrial diversification can lead to substantial increases in regional income, while at the same time increasing the resilience of a sugar industry facing decreasing sugar prices. Agri-industrial diversification drives land use diversification, which under current sugar prices does not lead to a reduction in sugarcane production. Water quality benefits from this land use diversification are mixed, and depend on the economic viability and erosion characteristics of the concerned production systems.spatial economics, environmental economics, value chains, agri-industries, water quality, Environmental Economics and Policy, Land Economics/Use, C6, O18, Q13, Q53,

Group Manifold Reduction of Dual N=1 d=10 Supergravity

We perform a group manifold reduction of the dual version of N=1 d=10 supergravity to four dimensions. The effects of the 3- and 4-form gauge fields in the resulting gauged N=4 d=4 supergravity are studied in particular. The example of the group manifold SU(2)xSU(2) is worked out in detail, and we compare for this case the four-dimensional scalar potential with gauged N=4 supergravity.Comment: 22 pages, revised section 3, typos corrected. Published versio

Coherent perfect absorption and reflection in slow-light waveguides

We identify a family of unusual slow-light modes occurring in lossy multi-mode grating waveguides, for which either the forward or backward mode components, or both, become degenerate. In the fully-degenerate case, by varying the wave amplitudes in a uniform input waveguide, one can modulate between coherent perfect absorption (zero reflection) and perfect reflection. The perfectly-absorbed wave has anomalously short absorption length, scaling as the inverse 1/3 power of the absorptivity