Observation of twin beam correlations and quadrature entanglement by frequency doubling in a two-port resonator

We demonstrate production of quantum correlated and entangled beams by second harmonic generation in a nonlinear resonator with two output ports. The output beams at wavelength 428.5 nm exhibit 0.9 dB of nonclassical intensity correlations and 0.3 dB of entanglement.Comment: 5 pages, 7 figure

Stochastic Description of a Bistable Frustrated Unit

Mixed positive and negative feedback loops are often found in biological systems which support oscillations. In this work we consider a prototype of such systems, which has been recently found at the core of many genetic circuits showing oscillatory behaviour. Our model consists of two interacting species A and B, where A activates not only its own production, but also that of its repressor B. While the self-activation of A leads already to a bistable unit, the coupling with a negative feedback loop via B makes the unit frustrated. In the deterministic limit of infinitely many molecules, such a bistable frustrated unit is known to show excitable and oscillatory dynamics, depending on the maximum production rate of A which acts as a control parameter. We study this model in its fully stochastic version and we find oscillations even for parameters which in the deterministic limit are deeply in the fixed-point regime. The deeper we go into this regime, the more irregular these oscillations are, becoming finally random excitations whenever fluctuations allow the system to overcome the barrier for a large excursion in phase space. The fluctuations can no longer be fully treated as a perturbation. The smaller the system size (the number of molecules), the more frequent are these excitations. Therefore, stochasticity caused by demographic noise makes this unit even more flexible with respect to its oscillatory behaviour.Comment: 28 pages, 17 figure

The Formaldehyde Masers in Sgr B2: Very Long Baseline Array and Very Large Array Observations

Observations of two of the formaldehyde (H2CO) masers (A and D) in Sgr B2 using the VLBA+Y27 (resolution ~0.01") and the VLA (resolution ~9") are presented. The VLBA observations show compact sources (<10 milliarcseconds, <80 AU) with brightness temperatures >10^8 K. The maser sources are partially resolved in the VLBA observations. The flux densities in the VLBA observations are about 1/2 those of the VLA; and, the linewidths are about 2/3 of the VLA values. The applicability of a core-halo model for the emission distribution is demonstrated. Comparison with earlier H2CO absorption observations and with ammonia (NH3) observations suggests that H2CO masers form in shocked gas. Comparison of the integrated flux densities in current VLA observations with those in previous observations indicates that (1) most of the masers have varied in the past 20 years, and (2) intensity variations are typically less than a factor of two compared to the 20-year mean. No significant linear or circular polarization is detected with either instrument.Comment: 20 pages, 3 figures, 5 tables, accepted to Ap

Noise induced oscillations in non-equilibrium steady state systems

We consider effect of stochastic sources upon self-organization process being initiated with creation of the limit cycle. General expressions obtained are applied to the stochastic Lorenz system to show that departure from equilibrium steady state can destroy the limit cycle at certain relation between characteristic scales of temporal variation of principle variables. Noise induced resonance related to the limit cycle is found to appear if the fastest variations displays a principle variable, which is coupled with two different degrees of freedom or more.Comment: 11 pages, 4 figures. Submitted to Physica Script

Rendering an Account: An Open-State Archive in Postgraduate Supervision

The paper begins with a brief account of the transformation of research degree studies under the pressures of global capitalism and neo-liberal governmentality. A parallel transformation is occurring in the conduct of research through the use of information and communication technologies. Yet the potential of ICTs to shape practices of surveillance or to produce new student-supervisor relations and enhance the processes of developing the dissertation has received almost no critical attention. As doctoral supervisor and student, we then describe the features and uses of a web-based open state archive of the student's work-in-progress, developed by the student and accessible to his supervisor. Our intention was to encourage more open conversations between data and theorising, student and supervisor, and ultimately between the student and professional community. However, we recognise that relations of accountability, as these have developed within a contemporary "audit revolution" (Power, 1994, 1997) in universities, create particular "lines of visibility" (Munro, 1996). Thus while the open-state archive may help to redefine in less managerial terms notions of quality, transparency, flexibility and accountability, it might also make possible greater supervisory surveillance. How should we think about the panoptical potential of this archive? We argue that the diverse kinds of interactional patterns and pedagogical intervention it encourages help to create shifting subjectivities. Moreover, the archive itself is multiple, in bringing together an array of diverse materials that can be read in various ways, by following multiple paths. It therefore constitutes a collage, which we identify as a mode of cognition and of accounting distinct from but related to argument and narrative. As a more "open" text (Iser, 1978) it has an indeterminacy which may render it less open to abuse for the technologies of managerial accountability

Comparative safety and effectiveness of vedolizumab to tumour necrosis factor antagonist therapy for Crohn\u27s disease

© 2020 The Authors. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd Background: Direct comparisons are lacking between vedolizumab and tumour necrosis factor (TNF)-antagonist therapy in Crohn\u27s disease (CD). Aim: To compare safety and effectiveness of vedolizumab and TNF-antagonist therapy in adult CD patients. Methods: Retrospective observational cohort (May 2014–December 2017) propensity score-weighted comparison of vedolizumab vs TNF-antagonist therapy (infliximab, adalimumab, certolizumab) in CD. Propensity scores were weighted for age, prior treatments, disease complications, extent and severity, steroid dependence, and concomitant immunosuppressive drug use. The primary outcome was comparative risk for infections or non-infectious serious adverse events (requiring antibiotics, antivirals, antifungals, hospitalisation, or treatment discontinuation, or resulting in death). Secondary comparative effectiveness outcomes were clinical remission (resolution of CD-related symptoms), steroid-free clinical remission and endoscopic remission (absence of ulcers/erosions). Results: We included 1266 patients (n = 659 vedolizumab). Rates of non-infectious serious adverse events (odds ratio [OR] 0.072, 95% confidence interval [CI] 0.012-0.242), but not serious infections (OR 1.183, 95% CI 0.786-1.795), were significantly lower with vedolizumab vs TNF-antagonist therapy. Safety comparisons for non-infectious serious adverse events remained significant after adjusting for differences in duration of exposure. No significant difference was observed between vedolizumab and TNF-antagonist therapy for clinical remission (hazard ratio [HR] 0.932, 95% CI 0.707-1.228), steroid-free clinical remission (HR 1.250, 95% CI 0.677-2.310) or endoscopic remission (HR 0.827, 95% CI 0.595-1.151). TNF-antagonist therapy was associated with higher treatment persistence compared with vedolizumab. Conclusions: There was a lower risk of non-infectious serious adverse events, but not serious infections, with vedolizumab vs TNF-antagonist therapy, with no significant difference for achieving disease remission

The Importance of Forage Legume Inclusion in Agricultural Swards to Enhance Earthworm Activity and Water Infiltration Rates

Increased grassland productivity in temperate regions has largely been achieved through perennial ryegrass Lolium perenne (PRG), coupled with large quantities of nitrogen fertiliser. However, concern is growing regarding the negative implications of excessive dependence on nitrogen fertilisers. Research has demonstrated the benefits of legume inclusion on primary productivity, however, their potential to influence other processes is less well established. Sampling was undertaken in autumn 2017 on twenty randomised plots representing five sward types, replicated four times. These had been established and managed by cutting since 2013. Sward types included: 1) PRG (250kg N ha-1 yr-1 ); 2) PRG; 3) PRG and white clover Trifolium repens; 4) 6 species mix comprised of PRG, timothy Phleum pratense, cocksfoot Dactylis glomerata, white clover, red clover Trifolium pratensis and greater birdsfoot trefoil Lotus pedunculatus; 5) species included in mix 4 with the addition of ribwort plantain Plantago lanceolate, chicory Cichorium intybus and yarrow Achillea millefolium. Mixes 2-5 inclusive received 90kg N ha-1 yr-1 . Measurements included: soil bulk density, water infiltration rates, and estimated earthworm activity via surface cast counts. Soil bulk density did not differ in response to sward type. However, highest infiltration rates were recorded within the PRG and white clover swards, with an average of 29.7 (±3.5) mm hr-1 , while lowest rates were recorded from the two PRG monocultures (2.43 (±0.5) and 4.2 (±1.2) mm hr⁻¹ for the 90 and 250 kg N ha-1 yr-1 swards respectively). Surface cast numbers differed significantly between sward types (P\u3c 0.001). Numbers ranged from 127 (±7) casts m⁻² for PRG & white clover, to 48 (±5) casts m⁻² for the PRG monocultures. Our findings indicate the importance of legume inclusion within agricultural grasslands managed under reduced nitrogen fertiliser inputs for wider ecosystem service provision

Excitations in the Halo Nucleus He-6 Following The Li-7(gamma,p)He-6 Reaction

A broad excited state was observed in 6-He with energy E_x = 5 +/- 1 MeV and width Gamma = 3 +/- 1 MeV, following the reaction Li-7(gamma,p)He-6. The state is consistent with a number of broad resonances predicted by recent cluster model calculations. The well-established reaction mechanism, combined with a simple and transparent analysis procedure confers considerable validity to this observation.Comment: 3 pages of LaTeX, 3 figures in PostScript, approved for publication in Phys. Rev. C, August, 200

Persistence, extinction and spatio-temporal synchronization of SIRS cellular automata models

Spatially explicit models have been widely used in today's mathematical ecology and epidemiology to study persistence and extinction of populations as well as their spatial patterns. Here we extend the earlier work--static dispersal between neighbouring individuals to mobility of individuals as well as multi-patches environment. As is commonly found, the basic reproductive ratio is maximized for the evolutionary stable strategy (ESS) on diseases' persistence in mean-field theory. This has important implications, as it implies that for a wide range of parameters that infection rate will tend maximum. This is opposite with present results obtained in spatial explicit models that infection rate is limited by upper bound. We observe the emergence of trade-offs of extinction and persistence on the parameters of the infection period and infection rate and show the extinction time having a linear relationship with respect to system size. We further find that the higher mobility can pronouncedly promote the persistence of spread of epidemics, i.e., the phase transition occurs from extinction domain to persistence domain, and the spirals' wavelength increases as the mobility increasing and ultimately, it will saturate at a certain value. Furthermore, for multi-patches case, we find that the lower coupling strength leads to anti-phase oscillation of infected fraction, while higher coupling strength corresponds to in-phase oscillation.Comment: 12page