On the Role of Global Warming on the Statistics of Record-Breaking Temperatures

We theoretically study long-term trends in the statistics of record-breaking daily temperatures and validate these predictions using Monte Carlo simulations and data from the city of Philadelphia, for which 126 years of daily temperature data is available. Using extreme statistics, we derive the number and the magnitude of record temperature events, based on the observed Gaussian daily temperatures distribution in Philadelphia, as a function of the number of elapsed years from the start of the data. We further consider the case of global warming, where the mean temperature systematically increases with time. We argue that the current warming rate is insufficient to measurably influence the frequency of record temperature events over the time range of the observations, a conclusion that is supported by numerical simulations and the Philadelphia temperature data.Comment: 11 pages, 6 figures, 2-column revtex4 format. For submission to Journal of Climate. Revised version has some new results and some errors corrected. Reformatted for Journal of Climate. Second revision has an added reference. In the third revision one sentence that explains the simulations is reworded for clarity. New revision 10/3/06 has considerable additions and new results. Revision on 11/8/06 contains a number of minor corrections and is the version that will appear in Phys. Rev.

Citizens' Blame of Politicians for Public Service Failure: Experimental Evidence about Blame Reduction through Delegation and Contracting

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordTheories of blame suggest that contracting out public service delivery reduces citizens' blame of politicians for service failure. The authors use an online experiment with 1,000 citizen participants to estimate the effects of information cues summarizing service delivery arrangements on citizens' blame of English local government politicians for poor street maintenance. Participants were randomized to one of four cues: no information about service delivery arrangements, politicians' involvement in managing delivery, delegation to a unit inside government managing delivery, and delegation through a contract with a private firm managing delivery. The politicians managing delivery cue raises blame compared to citizens having no information. However, the contract with a private firm cue does not reduce blame compared to either no information or the politicians managing delivery cue. Instead, the delegation to a unit inside government cue reduces blame compared to politicians managing delivery, suggesting that delegation to public managers, not contracting, reduces blame in this context.Funding support is acknowledged from European Community's Seventh Framework Programme, Grant no. 266887, Coordinating for Cohesion in the Public Sector of the Future

Effects of green manure storage and incorporation methods on greenhouse gas fluxes and N mineralization after soil application

Organic arable farming faces challenges with low crop yields, partly due to inefficient use of green manure-derived nitrogen (N). Under current farming practices, green manure leys are often cut and mulched during the growing season with the associated risk of environmental N losses, leading to eutrophication and global warming. In this 3-month incubation experiment, we tested a new green manure management strategy as part of the ICROFS project HighCrop. With the new strategy, green manure leys are instead harvested and preserved until the following spring either as compost mixed with straw (grass-clover:straw, 4:1, w:w) or as silage of harvested ley biomass. In spring, these two green manure materials can then be used for targeted fertilization of spring sown crops. The objectives of the study were to: • Assess how storage methods (compost vs. silage) affect N2O fluxes and soil respiratory CO2 emissions after soil application of preserved grass-clover green manure. • Determine whether the greenhouse gas fluxes are influenced by the incorporation method, more specifically harrowing (simulated by mixing the material into the top 5 cm soil layer) and ploughing (the material placed at 15 cm depth). • Compare composted and ensiled green manures concerning their abilities to provide plant-available N during a 3-month period. During the experiment, gas fluxes were measured at nine occasion followed by eight destructive soil harvests. In total, the study included 192 soil units that were incubated at 15 °C in darkness. Each unit consisted of a packed soil core (26 cm high × 10 cm diameter) with bulk density of 1.07 g cm-3 and gravimetric soil moisture of 20 %. The addition of compost and silage corresponded to a fertilization rate of 120 kg total N ha-1. A mineral fertilizer treatment was included as a reference and received 80 kg NH4-N ha-1. Compared to the more degraded compost, the silage material had a high content of labile compound. In addition, incorporation of green manure by harrowing was expected to improve soil microbes’ access to the materials, and thereby increase the decomposition rate. In line with this, cumulative CO2 emissions from the green manure treatments was lowest for compost incorporated by ploughing and highest for silage incorporated by harrowing. Between 32 and 54 % of the added green manure carbon was respired as CO2 during the 3-month experiment. Interestingly, mineral fertilizer suppressed soil respiratory CO2 emission. Generally, N2O emissions were higher from the silage-amended soils than from soils fertilized with compost. Especially, silage incorporated by ploughing gave rise to increased N2O effluxes, corresponding to 0.3 % of applied total N during the 3-month period. This could partly result from denitrification of initial soil nitrate, stimulated by high local oxygen consumption in the labile silage layer. In contrast, compost incorporated by harrowing caused a downwards N2O flux into the soil, presumably an effect of lacking mineral N availability in this treatment. Overall, our study showed that emissions of N2O can be reduced by incorporating green manure using harrowing instead of ploughing. Net mineralization of green manure-derived N was absent until more than three weeks after incorporation of the materials. Over the 3-month experiment, grass-clover silage provided the highest net release of inorganic N with preliminary results corresponding to 38-43 kg N ha-1, irrespective of the incorporation method used. In contrast, no increase in soil mineral N was observed for the composted grass-clover and straw mixture compared to the unfertilized control soil. In fact, soil incorporation of compost by harrowing caused immobilization of soil mineral nitrogen 1-2 months after experimental set-up

Chalcogenide-glass polarization-maintaining photonic crystal fiber for mid-infrared supercontinuum generation

In this paper, we report the design and fabrication of a highly birefringent polarization-maintaining photonic crystal fiber (PM-PCF) made from chalcogenide glass, and its application to linearly-polarized supercontinuum (SC) generation in the mid-infrared region. The PM fiber was drawn using the casting method from As38Se62 glass which features a transmission window from 2 to 10 $\mu m$ and a high nonlinear index of 1.13.10$^{-17}$m$^{2}$W$^{-1}$. It has a zero-dispersion wavelength around 4.5 $\mu m$ and, at this wavelength, a large birefringence of 6.10$^{-4}$ and consequently strong polarization maintaining properties are expected. Using this fiber, we experimentally demonstrate supercontinuum generation spanning from 3.1-6.02 $\mu m$ and 3.33-5.78 $\mu m$ using femtosecond pumping at 4 $\mu m$ and 4.53 $\mu m$, respectively. We further investigate the supercontinuum bandwidth versus the input pump polarization angle and we show very good agreement with numerical simulations of the two-polarization model based on two coupled generalized nonlinear Schr\"odinger equations.Comment: 13 pages, 8 figure

Kløvergræs ensilage og kompost som grøngødning

En ny strategi kan måske forbedre udnyttelsen af det kvælstof, som fikseres af kløverplanter i økologisk planteavl. Vores studie viste en større frigivelse af kvælstof fra ensileret kløvergræs end fra kompost af kløvergræs iblandet halm. Samtidig fandt vi, at indarbejdning af grøngødning ved harvning frem for pløjning reducerede udledningen af den stærke drivhusgas, lattergas

Nitrogen mineralization and greenhouse gas emissions after soil incorporation of ensiled and composted grass-clover as green manure

This 3-month incubation study showed that ensiled grass-clover was a better nitrogen (N) source than a composted grass-clover and straw mix (grass-clover:straw, 4:1, w:w), owing to the high content of labile compounds compared to the more degraded compost. Our study also indicated that emissions of the strong greenhouse gas nitrous oxide (N2O) can be reduced by incorporating green manure using harrowing instead of ploughing. The silage-derived N release by the end of the incubation was equivalent to 38-42 kg N ha-1, which corresponded to one third of the N applied in silage, with no difference between ploughing and harrowing. In contrast, no net release of mineral N was detected from the composted grass-clover

A new neurosurgical tool incorporating differential geometry and cellular automata techniques

Using optical coherence imaging, it is possible to visualize seizure progression intraoperatively. However, it is difficult to pinpoint an exact epileptic focus. This is crucial in attempts to minimize the amount of resection necessary during surgical therapeutic interventions for epilepsy and is typically done approximately from visual inspection of optical coherence imaging stills. In this paper, we create an algorithm with the potential to pinpoint the source of a seizure from an optical coherence imaging still. To accomplish this, a grid is overlaid on optical coherence imaging stills. This then serves as a grid for a two-dimensional cellular automation. Each cell is associated with a Riemannian curvature tensor representing the curvature of the brain's surface in all directions for a cell. Cells which overlay portions of the image which show neurons that are firing are considered "depolarized"

Sharp estimates on the first eigenvalue of the p-Laplacian with negative Ricci lower bound

We complete the picture of sharp eigenvalue estimates for the p-Laplacian on a compact manifold by providing sharp estimates on the first nonzero eigenvalue of the nonlinear operator $\Delta_p$ when the Ricci curvature is bounded from below by a negative constant. We assume that the boundary of the manifold is convex, and put Neumann boundary conditions on it. The proof is based on a refined gradient comparison technique and a careful analysis of the underlying model spaces.Comment: Sign mistake fixed in the proof of the gradient comparison theorem (theorem 5.1 pag 10), and some minor improvements aroun

2015 Update on Acute Adverse Reactions to Gadolinium based Contrast Agents in Cardiovascular MR. Large Multi-National and Multi-Ethnical Population Experience With 37788 Patients From the EuroCMR Registry

Objectives: Specifically we aim to demonstrate that the results of our earlier safety data hold true in this much larger multi-national and multi-ethnical population. Background: We sought to re-evaluate the frequency, manifestations, and severity of acute adverse reactions associated with administration of several gadolinium- based contrast agents during routine CMR on a European level. Methods: Multi-centre, multi-national, and multi-ethnical registry with consecutive enrolment of patients in 57 European centres. Results: During the current observation 37788 doses of Gadolinium based contrast agent were administered to 37788 patients. The mean dose was 24.7 ml (range 5–80 ml), which is equivalent to 0.123 mmol/kg (range 0.01 - 0.3 mmol/kg). Forty-five acute adverse reactions due to contrast administration occurred (0.12 %). Most reactions were classified as mild (43 of 45) according to the American College of Radiology definition. The most frequent complaints following contrast administration were rashes and hives (15 of 45), followed by nausea (10 of 45) and flushes (10 of 45). The event rate ranged from 0.05 % (linear non-ionic agent gadodiamide) to 0.42 % (linear ionic agent gadobenate dimeglumine). Interestingly, we also found different event rates between the three main indications for CMR ranging from 0.05 % (risk stratification in suspected CAD) to 0.22 % (viability in known CAD). Conclusions: The current data indicate that the results of the earlier safety data hold true in this much larger multi-national and multi-ethnical population. Thus, the “off-label” use of Gadolinium based contrast in cardiovascular MR should be regarded as safe concerning the frequency, manifestation and severity of acute events