Quantum storage on subradiant states in an extended atomic ensemble

A scheme for coherent manipulation of collective atomic states is developed such that total subradiant states, in which spontaneous emission is suppressed into all directions due to destructive interference between neighbor atoms, can be created in an extended atomic ensemble. The optimal conditions for creation of such states and suitability of them for quantum storage are discussed. It is shown that in order to achieve the maximum signal-to-noise ratio the shape of a light pulse to be stored and reconstructed using a homogeneously broadened absorbtion line of an atomic system should be a time-reversed regular part of the response function of the system. In the limit of high optical density, such pulses allow one to prepare collective subradiant atomic states with near flat spatial distribution of the atomic excitation in the medium.Comment: V2: considerably revised (title, text). V3: minor changes - final version as published in PR

The impact of long-term elevated CO2 on C and N retention in stable SOM pools

Elevated atmospheric CO2 frequently increases plant production and concomitant soil C inputs, which may cause additional soil C sequestration. However, whether the increase in plant production and additional soil C sequestration under elevated CO2 can be sustained in the long-term is unclear. One approach to study C-N interactions under elevated CO2 is provided by a theoretical framework that centers on the concept of progressive nitrogen limitation (PNL). The PNL concept hinges on the idea that N becomes less available with time under elevated CO2. One possible mechanism underlying this reduction in N availability is that N is retained in long-lived soil organic matter (SOM), thereby limiting plant production and the potential for soil C sequestration. The long-term nature of the PNL concept necessitates the testing of mechanisms in field experiments exposed to elevated CO2 over long periods of time. The impact of elevated CO2 and N-15 fertilization on L. perenne and T. repens monocultures has been studied in the Swiss FACE experiment for ten consecutive years. We applied a biological fractionation technique using long-term incubations with repetitive leaching to determine how elevated CO2 affects the accumulation of N and C into more stable SOM pools. Elevated CO2 significantly stimulated retention of fertilizer-N in the stable pools of the soils covered with L. perenne receiving low and high N fertilization rates by 18 and 22%, respectively, and by 45% in the soils covered by T. repens receiving the low N fertilization rate. However, elevated CO2 did not significantly increase stable soil C formation. The increase in N retention under elevated CO2 provides direct evidence that elevated CO2 increases stable N formation as proposed by the PNL concept. In the Swiss FACE experiment, however, plant production increased under elevated CO2, indicating that the additional N supply through fertilization prohibited PNL for plant production at this site. Therefore, it remains unresolved why elevated CO2 did not increase labile and stable C accumulation in these systems

Lower Paleozoic Sequence Stratigraphy, Deposystems and Paleogeography of Northwestern Ordos Basin, North China

The Ordos basin rests upon the North China Block and is one of the largest sedimentary basins in north China, with more than 15 km of Phanerozoic strata. Published estimates suggest that over 2000 m of carbonates and lesser amounts of siliciclastics were deposited on the North China Carbonate Platform (NCCP) from the Lower Can1brian through the Middle Ordovician. However, lower Paleozoic facies successions and deposystems of northwestern Ordos basin remain poorly represented in western literature. This paper constrains depositional environments, lithologies, facies relationships and sea-level history of the northwestern part of the North China block (NCB) in an effort to further document the Early Paleozoic geologic history of western Ordos basin. New stratigraphic data come largely from measured sections in the Zhuozi Shan and Helan Shan in northwest Ordos basin. Strata in the mountains of northwestern Ordos are divided into eleven lithofacies assemblages, distinguished by lithology, stacking patterns and sedimentary structures. Lithofacies assemblages in northwest Ordos are grouped into four lithostratigraphic units that make up the composite type section. Unit A is dominantly composed of shale and mudrock lithofacies, Unit B is dominantly composed of thin-bedded lime mudstone and banded and bioturbated lime mudstone to wackestone, Unit C is dominantly composed of quartz sandstone and dolostone and Unit D is dominantly composed of fossiliferous packstone. These four units were observed in all lower Paleozoic sections of the Helan Shan and Zhuozi Shan. Deposition of Middle Cambrian through lowermost Lower Ordovician strata in northwest Ordos basin occurred on a storm-influenced, mixed siliciclastic and carbonate, shallow-water ramp. Lateral trends in quartz sandstone, paleokarsts, thrombolites and section thickness suggest that accommodation space increased to the south. The depositional architecture changed in the Middle Ordovician to a carbonate shelf environment. The sea-level history of northwestern Ordos shows transgression through the Late Can1brian, regression in the Early Ordovician, followed by a Middle Ordovician transgression, corresponding with North American sea level signatures. Lower Paleozoic sections in northwestern Ordos basin are broadly similar to those previously described in western literature. However, based upon stratigraphic data, shoreline trends of the NCCP model are proved inapplicable to northwestern Ordos. There is no evidence for lower Paleozoic tectonics such as aulacogen-controlled subsidence and platform tilting as described by previous workers. The sea-level history interpreted for northwest Ordos basin is more similar to North American curves than to the North China Carbonate Platform model, suggesting a eustatic control on lithofacies stacking patterns in northwest Ordos basin

Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail

Experimental control strategies reducing the fungicide input at a practical scale

Phytophthora infestans is the most devastating disease in potato cultivation. Chemical control is necessary to ensure a healthy crop. At the same time Dutch governmental policy asks for a reduction of the environmental impact of potato late blight control by 75% in 2012 as compared to 1996-1998. The aim of the experiments was to compare Decision Support Systems with different approaches to blight risk management for their ability to reduce the fungicide input without compromising control efficacy. Considerable savings, up to 81% when compared to weekly, full dose rate, spray schedules, can be achieved by using information on cultivar resistance, length of the critical period and disease pressure to decide whether or not to spray. The subroutine calculating the potential for viable transport of spores is only effective on resistant varieties as the threshold was exceeded with every critical period on less resistant cultivars. Implications of the experimental control strategies for agricultural practise are discusse

Coherent control of collective spontaneous emission in an extended atomic ensemble and quantum storage

Coherent control of collective spontaneous emission in an extended atomic ensemble resonantly interacting with single-photon wave packets is analyzed. A scheme for coherent manipulation of collective atomic states is developed such that superradiant states of the atomic system can be converted into subradiant ones and vice versa. Possible applications of such a scheme for optical quantum state storage and single-photon wave packet shaping are discussed. It is shown that also in the absence of inhomogeneous broadening of the resonant line, single-photon wave packets with arbitrary pulse shape may be recorded as a subradiant state and reconstructed even although the duration of the wave packets is larger than the superradiant life-time. Specifically the applicability for storing time-bin qubits, which are used in quantum cryptography is analyzed.Comment: 11 pages, 4 figures, submitted to PR

Scald risk in social housing can be reduced through thermostatic control system without increasing Legionella risk: a cluster randomised trial.

OBJECTIVE: To quantify the effects of a thermostatic control system in social (public) housing on the prevalence of dangerous (>60°C) water temperatures and on fuel consumption. DESIGN: Pair-matched double-blind cluster randomised controlled trial. SETTING: Social housing in a deprived inner-London borough. PARTICIPANTS: 150 households recruited as clusters from 22 social housing estates. Four small estates were combined into two clusters (resulting in a total of 10 pairs of clusters). INTERVENTION: Social housing estate boiler houses were randomised to a thermostatic control sterilisation programme (heating water to 65°C during 00:00-06:00 h and to 50°C from 06:00 to 00:00 h daily) or to standard control (constant temperature 65°C). MAIN OUTCOME MEASURES: Water temperature over 60°C ('dangerous') after running taps for 1 min and daily fuel consumption (cubic feet of gas). RESULTS: 10 clusters (80 households) were allocated to the sterilisation programme and 10 clusters (70 households) to control, of which 73 and 67 households, respectively, were analysed. Prevalence of dangerous (>60°C) hot water temperatures at 1 min was significantly reduced with the sterilisation programme (mean of cluster prevalence 1% in sterilisation programme group vs 34% in control group; absolute difference 33%, 95% CI 12% to 54%; p=0.006). Prevalence of high (>55°C) hot water temperatures at 1 min was significantly reduced (31% sterilisation vs 59% control; absolute difference 28%, 95% CI 9% to 47%; p=0.009). Gas consumption per day reduced more in the control group than in the sterilisation programme group, although not statistically significantly (p=0.125). CONCLUSIONS: The thermostatic control with daily sterilisation was effective in capping hot water temperatures and therefore reduced scald risk. Although expected to save energy, fuel consumption was increased relative to the control group. Trial registration ClinicalTrials.gov ID: NCT00874692

Decomposing the queue length distribution of processor-sharing models into queue lengths of permanent customer queues

We obtain a decomposition result for the steady state queue length distribution in egalitarian processor-sharing (PS) models. In particular, for an egalitarian PS queue with $K$ customer classes, we show that the marginal queue length distribution for class $k$ factorizes over the number of other customer types. The factorizing coefficients equal the queue length probabilities of a PS queue for type $k$ in isolation, in which the customers of the other types reside \textit{ permanently} in the system. Similarly, the (conditional) mean sojourn time for class $k$ can be obtained by conditioning on the number of permanent customers of the other types. The decomposition result implies linear relations between the marginal queue length probabilities, which also hold for other PS models such as the egalitarian processor-sharing models with state-dependent system capacity that only depends on the total number of customers in the system. Based on the exact decomposition result for egalitarian PS queues, we propose a similar decomposition for discriminatory processor-sharing (DPS) models, and numerically show that the approximation is accurate for moderate differences in service weights. \u

Statistical Trends in Women’s Participation in Science: Commentary on Valla and Ceci (2011)

Valla and Ceci (2011, this issue) describe the participation of women in science and claim that the increases in quantitative fields (e.g., mathematics, engineering, and physical sciences) are an exception to the statement that “Women’s growth in the scientific workforce has been meteoric over the past 40 years” (p. 134). We disagree and present statistics demonstrating a more positive view of the increase of the number of women in quantitative fields.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Dual inoculation of Pisum sativum with Rhizobium leguminosarum and Penicillium bilaji

Non-Peer ReviewedTo investigate the effect of single versus dual inoculation of Trapper-pea with Rhizobium leguminosarum and Penicillium bilaji, a P-solubilizing fungi, an experiment under controlled conditions was carried out using a sandy soil containing low levels of available N and P. The following treatments were installed: control, P application at a rate of 100 kg P/ha, pea inoculated with P. bilaji (PB50) applied at recommended rate as PB50™ supplied by Philom Bios, pea inoculated with R. leguminosarum (R) and all possible combinations of the four treatments. To determine N2 fixation by 15N-natural abundance, flax was included as the reference crop. Treatments were replicated four times and placed in a randomized complete block design. Throughout the experiment, soil was kept at 75 % of field capacity and additional light was provided. After 8 weeks of growth, two plants/pot were harvested and total shoot weight, total N, total P, percent N derived from N2 and the amount of N2 fixed was determined. P fertilization increased yield significantly from 3.0 to 4.2 g/pot. PB50 alone increased shoot yield to 3.6 g/pot. Whereas pea inoculated with R showed only a small yield increase, the additional application of P increased yield to 4.1 g/pot. Application of P and both the inoculants reduced yield to 3.7 g/pot. Total N accumulation was highly dependent on the presence of R. Whereas the control, which was sparsely nodulated, showed a total N yield of 62.3 mg N/pot, inoculation with R and P fertilization increased total N to 100 mg N/pot. Double inoculation with Rand PB50 along with P fertilization reduced the total N yield to 95 mg N/pot. Pea inoculated with PB50 and R showed a total N yield of 78.5 mg N/pot. The highest N2-fixing activity (39 % Ndfa or 39.6 mg of N) was observed in pea inoculated with R and which had received inorganic P. Total P uptake was solely dependent on P fertilization. Results indicate that PB50 had no beneficial influence on P uptake and N2-fixing activity