18,617 research outputs found

    The Soft Path for Water

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    There are two primary ways of meeting water-related needs, or more poetically, two paths. One path -- the "hard" path -- relies almost exclusively on centralized infrastructure and decision making: dams and reservoirs, pipelines and treatment plants, water departments and agencies. It delivers water, mostly of potable quality, and takes away wastewater. The second path -- the "soft" path -- may also rely on centralized infrastructure, but complements it with extensive investment in decentralized facilities, efficient technologies, and human capital.1 It strives to improve the overall productivity of water use rather than seek endless sources of new supply. It delivers diverse water services matched to the users' needs and works with water users at local and community scales. This chapter tells the tale of these paths up to the present. Decisions made today, and actions of future generations, will write the conclusion of the story

    Spins coupled to a Z2Z_2-Regge lattice in 4d

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    We study an Ising spin system coupled to a fluctuating four-dimensional Z2Z_2-Regge lattice and compare with the results of the four-dimensional Ising model on a regular lattice. Particular emphasis is placed on the phase transition of the spin system and the associated critical exponents. We present results from finite-size scaling analyses of extensive Monte Carlo simulations which are consistent with mean-field predictions.Comment: Lattice2001(surfaces), 3 pages, 2 figure

    Cluster Algorithm for a Solid-On-Solid Model with Constraints

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    We adapt the VMR (valleys-to-mountains reflections) algorithm, originally devised by us for simulations of SOS models, to the BCSOS model. It is the first time that a cluster algorithm is used for a model with constraints. The performance of this new algorithm is studied in detail in both phases of the model, including a finite size scaling analysis of the autocorrelations.Comment: 10 pages, 3 figures appended as ps-file

    Moral hazard and bail-out in fiscal federations: evidence for the German Länder

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    We identify investor moral hazard in the German fiscal federation. Our identification strategy is based on a variable, which was used by the German Federal Constitutional Court as an indicator to determine eligibility of two German states (Länder) to a bail-out, the interest payments-to-revenue ratio. While risk premia measured in the German sub-national bond market react significantly to the relative debt level of a state (Land), we also find that a larger interest payments-to-revenue ratio counter-intuitively lowers risk premia significantly. Furthermore, with increasing values the risk premia decrease more strongly. This is evidence of investor moral hazard, because a larger indicator value increases the likelihood of receiving a bail-out payment. Quantitatively, the effects are, however, quite small. Our findings are robust to a variety of sample changes. In addition, we provide a case study of the recent Federal Constitutional Court ruling on the Land Berlin, which had filed for additional federal funds. The negative response of the court did not lead to a change in financial markets' bail-out expectations. In sum, our results indicate significant investor moral hazard in the sub-national German bond market. --moral hazard,bail-out,sovereign bond spreads,fiscal federalism,Germany

    The impact of the AIDS epidemic on the lives of older people in rural Uganda

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    Critical exponents of a three dimensional O(4) spin model

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    By Monte Carlo simulation we study the critical exponents governing the transition of the three-dimensional classical O(4) Heisenberg model, which is considered to be in the same universality class as the finite-temperature QCD with massless two flavors. We use the single cluster algorithm and the histogram reweighting technique to obtain observables at the critical temperature. After estimating an accurate value of the inverse critical temperature \Kc=0.9360(1), we make non-perturbative estimates for various critical exponents by finite-size scaling analysis. They are in excellent agreement with those obtained with the 4ϵ4-\epsilon expansion method with errors reduced to about halves of them.Comment: 25 pages with 8 PS figures, LaTeX, UTHEP-28

    Tracking daily fatigue fluctuations in multiple sclerosis : ecological momentary assessment provides unique insights

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    The preparation of this manuscript was supported by a UK Economic and Social Research Council (ESRC) PhD studentship (ES/1026266/1) awarded to DP. The study was funded by the Psychology Unit at the University of Southampton. The authors declare that they have no conflict of interest. The authors thank all participants of this study. Open access via Springer Compact Agreement.Peer reviewedPublisher PD

    Comments on Sweeny and Gliozzi dynamics for simulations of Potts models in the Fortuin-Kasteleyn representation

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    We compare the correlation times of the Sweeny and Gliozzi dynamics for two-dimensional Ising and three-state Potts models, and the three-dimensional Ising model for the simulations in the percolation prepresentation. The results are also compared with Swendsen-Wang and Wolff cluster dynamics. It is found that Sweeny and Gliozzi dynamics have essentially the same dynamical critical behavior. Contrary to Gliozzi's claim (cond-mat/0201285), the Gliozzi dynamics has critical slowing down comparable to that of other cluster methods. For the two-dimensional Ising model, both Sweeny and Gliozzi dynamics give good fits to logarithmic size dependences; for two-dimensional three-state Potts model, their dynamical critical exponent z is 0.49(1); the three-dimensional Ising model has z = 0.37(2).Comment: RevTeX, 4 pages, 5 figure

    The macroeconomic effects of exogenous fiscal policy shocks in Germany: a disaggregated SVAR analysis

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    We investigate the short-term effects of fiscal policy shocks on the German economy following the SVAR approach by Blanchard and Perotti (2002). We find that direct government expenditure shocks increase output and private consumption on impact with low statistical significance, while they decrease private investment, though insignificantly. For the sub-category government investment – in contrast to government consumption – a positive output effect is found, which is statistically significant until 12 quarters ahead. Allowing for anticipation effects of fiscal policy does not change the sign of the positive consumption response. Anticipated expenditure shocks have significant effects on output when the shock is realized, but not in the period of anticipation. In sum, effects of expenditure shocks are only short-lived. Government net revenue shocks do not affect output with statistical significance. However, when splitting up this aggregate, direct taxes lower output significantly, while small indirect tax revenue shocks have little effects. Compensation of public employees is equally not effective in stimulating the economy. --Fiscal policy,government spending,net revenue,policy anticipation,structural vector autoregression

    Contact-induced disturbances in personal pronoun systems in the Chadic – Benue-Congo convergence zone in Central Nigeria

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    The paper looks at personal pronoun systems in languages of the convergence zone on both sides of the borderline between Benue-Congo and Chadic. Focus is on inventories and systems, meaning the overall interrelationship of pronoun shapes across the categories of person, number, grammatical gender and noun class (3rd person concord). The issues to be explored are (i) whether the personal pronoun systems as such provide any further indication towards the Sprachbund idea implied in Wolff & Gerhardt (1977), and (ii) whether one can identify some unusual features of or patterns within the systems, which are shared by languages on both sides of the line separating Benue-Congo and Chadic, and which are of such nature as to strengthen the hypothesis of a cross-genetic convergence zone. The answers provided are affirmative: In addition to cross-genetic borrowing of pronoun shapes, which is generally considered rare and/or at least remarkable, pronoun systems as such and across the convergence zone show at least two rather quirky disturbances of the expected pattern that can hardly be explained but by rather surprising instances of cross-language interference. These two kinds of disturbance within systems will be discussed under the headings of “category shifting” and “circumfix conjugational pattern” emergence.Given the present state of knowledge, the paper can only point out promising lines of detailed historical research: Any attempt to provide final answers would be premature at this stage
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