515 research outputs found

    Plant breeding influences the performance of temperate pasture species in the subtropics

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    Data from a series of experiments over a 15-year period in the subtropics were interrogated to determine whether plant breeding had influenced the performance of ryegrass and lucerne in the subtropics of Australia. It was found that, within sets of plant breeders' lines available for sowing in any one experiment, yield of the best experimental lines of perennial and annual ryegrasses and lucerne were almost always above that of standard cultivars. The range in rust resistance was not as great in annual ryegrass, with breeders' lines rarely being superior to the standard cultivars. However in perennial ryegrass and lucerne, the range of disease: resistance was greater and did show improvement relative to the standard cultivars. There was also a trend towards improved performance of breeders' lines over time. Those available between 1996 and 1999 showed an overall increase in yield over the general experimental mean, and the performance of the best and worst experimental lines in ryegrass and lucerne at the commencement of the study period (1978 for lucerne and 1992 for ryegrasses). Persistence of lucerne showed the reverse trend with an overall fall in the general experimental mean. Resistance to Phythophthora root rot (PRR) and leaf diseases improved over time but that for Colletotrichum crown rot (CCR) declined. The reasons for these trends are discussed

    Where Next for Formal Methods?

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    Hawking Spectrum and High Frequency Dispersion

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    We study the spectrum of created particles in two-dimensional black hole geometries for a linear, hermitian scalar field satisfying a Lorentz non-invariant field equation with higher spatial derivative terms that are suppressed by powers of a fundamental momentum scale k0k_0. The preferred frame is the ``free-fall frame" of the black hole. This model is a variation of Unruh's sonic black hole analogy. We find that there are two qualitatively different types of particle production in this model: a thermal Hawking flux generated by ``mode conversion" at the black hole horizon, and a non-thermal spectrum generated via scattering off the background into negative free-fall frequency modes. This second process has nothing to do with black holes and does not occur for the ordinary wave equation because such modes do not propagate outside the horizon with positive Killing frequency. The horizon component of the radiation is astonishingly close to a perfect thermal spectrum: for the smoothest metric studied, with Hawking temperature TH0.0008k0T_H\simeq0.0008k_0, agreement is of order (TH/k0)3(T_H/k_0)^3 at frequency ω=TH\omega=T_H, and agreement to order TH/k0T_H/k_0 persists out to ω/TH45\omega/T_H\simeq 45 where the thermal number flux is O(1020O(10^{-20}). The flux from scattering dominates at large ω\omega and becomes many orders of magnitude larger than the horizon component for metrics with a ``kink", i.e. a region of high curvature localized on a static worldline outside the horizon. This non-thermal flux amounts to roughly 10\% of the total luminosity for the kinkier metrics considered. The flux exhibits oscillations as a function of frequency which can be explained by interference between the various contributions to the flux.Comment: 32 pages, plain latex, 16 figures included using psfi

    Doctor Referral of Overweight People to Low Energy total diet replacement Treatment (DROPLET):pragmatic randomised controlled trial

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    Objective To test the effectiveness and safety of a total diet replacement (TDR) programme for routine treatment of obesity in a primary care setting. Design Pragmatic, two arm, parallel group, open label, individually randomised controlled trial. Setting 10 primary care practices in Oxfordshire, UK. Participants 278 adults who were obese and seeking support to lose weight: 138 were assigned to the TDR programme and 140 to usual care. 73% of participants were re-measured at 12 months. Interventions The TDR programme comprised weekly behavioural support for 12 weeks and monthly support for three months, with formula food products providing 810 kcal/day (3389 kJ/day) as the sole food during the first eight weeks followed by reintroduction of food. Usual care comprised behavioural support for weight loss from a practice nurse and a diet programme with modest energy restriction. Main outcome measures The primary outcome was weight change at 12 months analysed as intention to treat with mixed effects models. Secondary outcomes included biomarkers of cardiovascular and metabolic risk. Adverse events were recorded. Results Participants in the TDR group lost more weight (−10.7 kg) than those in the usual care group (−3.1 kg): adjusted mean difference −7.2 kg (95% confidence interval −9.4 to −4.9 kg). 45% of participants in the TDR group and 15% in the usual care group experienced weight losses of 10% or more. The TDR group showed greater improvements in biomarkers of cardiovascular and metabolic risk than the usual care group. 11% of participants in the TDR group and 12% in the usual care group experienced adverse events of moderate or greater severity. Conclusions Compared with regular weight loss support from a practice nurse, a programme of weekly behavioural support and total diet replacement providing 810 kcal/day seems to be tolerable, and leads to substantially greater weight loss and greater improvements in the risk of cardiometabolic disease

    Observation of Non-Exponential Orbital Electron Capture Decays of Hydrogen-Like 140^{140}Pr and 142^{142}Pm Ions

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    We report on time-modulated two-body weak decays observed in the orbital electron capture of hydrogen-like 140^{140}Pr59+^{59+} and 142^{142}Pm60+^{60+} ions coasting in an ion storage ring. Using non-destructive single ion, time-resolved Schottky mass spectrometry we found that the expected exponential decay is modulated in time with a modulation period of about 7 seconds for both systems. Tentatively this observation is attributed to the coherent superposition of finite mass eigenstates of the electron neutrinos from the weak decay into a two-body final state.Comment: 12 pages, 5 figure

    Finite 3π3\pi Cut Approximation for the πNNˉ\pi N\bar{N} Form Factor

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    Assuming the length of the 3π3\pi cut to be finite and approximating the integrated amplitude by a constant, we derive an expression for the πNNˉ\pi N\bar{N} form factor which is very close to that given by a simple pole. The specific predictions of the obtained form factor for the region of small momentum transfer are discussed along the lines of the Goldberger-Treiman relation.Comment: 17 pages, Late

    Ten Proofs of the Generalized Second Law

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    Ten attempts to prove the Generalized Second Law of Thermodyanmics (GSL) are described and critiqued. Each proof provides valuable insights which should be useful for constructing future, more complete proofs. Rather than merely summarizing previous research, this review offers new perspectives, and strategies for overcoming limitations of the existing proofs. A long introductory section addresses some choices that must be made in any formulation the GSL: Should one use the Gibbs or the Boltzmann entropy? Should one use the global or the apparent horizon? Is it necessary to assume any entropy bounds? If the area has quantum fluctuations, should the GSL apply to the average area? The definition and implications of the classical, hydrodynamic, semiclassical and full quantum gravity regimes are also discussed. A lack of agreement regarding how to define the "quasi-stationary" regime is addressed by distinguishing it from the "quasi-steady" regime.Comment: 60 pages, 2 figures, 1 table. v2: corrected typos and added a footnote to match the published versio

    Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

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    The cyclic deformation behavior of cryomilled (CM) AA5083 alloys was compared to that of conventional AA5083-H131. The materials studied were a 100 pct CM alloy with a Gaussian grain size average of 315 nm and an alloy created by mixing 85 pct CM powder with 15 pct unmilled powder before consolidation to fabricate a plate with a bimodal grain size distribution with peak averages at 240 nm and 1.8 μm. Although the ultra-fine-grain (UFG) alloys exhibited considerably higher tensile strengths than those of the conventional material, the results from plastic-strain-controlled low-cycle fatigue tests demonstrate that all three materials exhibit identical fatigue lives across a range of plastic strain amplitudes. The CM materials exhibited softening during the first cycle, similar to other alloys produced by conventional powder metallurgy, followed by continual hardening to saturation before failure. The results reported in this study show that fatigue deformation in the CM material is accompanied by slight grain growth, pinning of dislocations at the grain boundaries, and grain rotation to produce macroscopic slip bands that localize strain, creating a single dominant fatigue crack. In contrast, the conventional alloy exhibits a cell structure and more diffuse fatigue damage accumulation

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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