Photon transport in a dissipative chain of nonlinear cavities

We analyze a chain of coupled nonlinear optical cavities driven by a coherent source of light localized at one end and subject to uniform dissipation. We characterize photon transport by studying the populations and the photon correlations as a function of position. When complemented with input-output theory, these quantities provide direct information about photon transmission through the system. The position of single- and multi-photon resonances directly reflect the structure of the many-body energy levels. This shows how a study of transport along a coupled cavity array can provide rich information about the strongly correlated (many-body) states of light even in presence of dissipation. By means of a numerical algorithm based on the time-evolving block decimation scheme adapted to mixed states, we are able to simulate arrays up to sixty cavities.Comment: 12 pages, 14 figure

Energy transport between two integrable spin chains

We study the energy transport in a system of two half-infinite XXZ chains initially kept separated at different temperatures, and later connected and let free to evolve unitarily. By changing independently the parameters of the two halves, we highlight, through bosonisation and time-dependent matrix-product-state simulations, the different contributions of low-lying bosonic modes and of fermionic quasi-particles to the energy transport. In the simulations we also observe that the energy current reaches a finite value which only slowly decays to zero. The general pictures that emerges is the following. Since integrability is only locally broken in this model, a pre-equilibration behaviour may appear. In particular, when the sound velocities of the bosonic modes of the two halves match, the low-temperature energy current is almost stationary and described by a formula with a non-universal prefactor interpreted as a transmission coefficient. Thermalisation, characterized by the absence of any energy flow, occurs only on longer time-scales which are not accessible with our numerics.Comment: 15 pages, 14 figure

Spin-statistics relation for quantum Hall states

We prove a generic spin-statistics relation for the fractional quasiparticles that appear in abelian quantum Hall states on the disk. The proof is based on an efficient way for computing the Berry phase acquired by a generic quasiparticle translated in the plane along a circular path, and on the crucial fact that once the gauge-invariant generator of rotations is projected onto a Landau level, it fractionalizes among the quasiparticles and the edge. Using these results we define a measurable quasiparticle fractional spin that satisfies the spin-statistics relation. As an application, we predict the value of the spin of the composite-fermion quasielectron proposed by Jain; our numerical simulations agree with that value. We also show that Laughlin's quasielectrons satisfy the spin-statistics relation, but carry the wrong spin to be the anti-anyons of Laughlin's quasiholes. We continue by highlighting the fact that the statistical angle between two quasiparticles can be obtained by measuring the angular momentum whilst merging the two quasiparticles. Finally, we show that our arguments carry over to the non-abelian case by discussing explicitly the Moore-Read wavefunction.Comment: 7 + 11 pages, 4 + 6 figures. Significant improvement with respect to the original version: A non-Abelian (Moore-Read) state is discusse

Primary stroke prevention and hypertension treatment: which is the first-line strategy?

Hypertension (HT) is considered the main classic vascular risk factor for stroke and the importance of lowering blood pressure (BP) is well established. However, not all the benefit of antihypertensive treatment is due to BP reduction per se, as the effect of reducing the risk of stroke differs among classes of antihypertensive agents. Extensive evidences support that angiotensin-converting enzyme inhibitors (ACEI), angiotensin II receptor blockers (ARB), dihydropyridine calcium channel blockers (CCB) and thiazide diuretics each reduced risk of stroke compared with placebo or no treatment. Therefore, when combination therapy is required, a combination of these antihypertensive classes represents a logical approach. Despite the efficacy of antihypertensive therapy a large proportion of the population, still has undiagnosed or inadequately treated HT, and remain at high risk of stroke. In primary stroke prevention current guidelines recommend a systolic/diastolic BP goal of <140/<90 mmHg in the general population and <130/80 mmHg in diabetics and in subjects with high cardiovascular risk and renal disease. The recent release in the market of the fixed-dose combination (FDC) of ACEI or ARB and CCB should provide a better control of BP. However to confirm the efficacy of the FDC in primary stroke prevention, clinical intervention trials are needed

A network of sex and competition: the promiscuous mating system of an invasive weevil.

Invasive alien pest insect species represent a major threat for agriculture and biodiversity. Because chemical treatments employed to contrast such pests elicit serious environmental and human health problems, a great effort is currently directed to develop long term and environmentally friendly biological control strategies. However, the successful application of some promising techniques, such as the Sterile Insect Technique (SIT), requires a deep knowledge of the pest basic biology. Here, we argue that understanding pest sexual biology using a social network approach can significantly improve the performance of control strategies. For example, SIT may benefit from understanding how individuals interact and how males accede to reproduction, in order to target the most reproductively active and polygamic males. In this paper we studied the socio-sexual networks of the Asian red palm weevil (RPW) Rhynchophorus ferrugineus, a worldwide invader which is causing heavy economic impacts on several palm species. We found that the RPW has a highly promiscuous mating system, characterized by forced interruptions of pair copulations by additional males. The social network is highly non-random nor regular: few males almost monopolize reproduction, behaving as key-players in the network of matings. Additionally, males have a stable pattern of sexual behaviour over time. We use RPW social network as a case study to direct the development of management techniques such as SIT strateg

Internal carotid artery fibromuscular dysplasia in arterial hypertension: Management in clinical practice

Fibromuscular dysplasia (FMD) reminds of a rare form of secondary arterial hypertension occurring in young people and involving the renal arteries. FMD may also involve vertebral, subclavian, mesenteric, iliac arteries and carotid arteries. FMD of internal carotid arteries is a rare finding that is frequently incidental and asymptomatic. It usually occurs in middle-aged women and is secondary to media-intima fibrodysplasia. The carotid artery may be elongated or kinked and associated cerebral aneurysms have been reported. Symptoms including transient ischaemic attack or stroke are uncommon and are related to decrease of blood flow or embolization by platelet aggregates. At the onset, differential diagnosis with vasculitis must be placed. Computed tomography or magnetic resonance imaging (MRI) angiography demonstrates bilateral high-grade stenosis with the characteristic "string of beads" pattern. Antiplatelet medication is the accepted therapy for asymptomatic lesions. Graduated endoluminal surgical dilation is an outmoded therapy, no longer used in most medical centres. Current percutaneous angioplasty is the preferred treatment for symptomatic carotid FMD, but no randomized controlled trials comparing this methodology with surgery is available. The management of a case of arterial systemic FMD in a 52-year-old women, diagnosed after a hypertensive crysis, is discussed. Imaging methods disclosed stenoses of carotid arteries, of celiac tripod and of superior mesenteric artery. Because of high risk associated to endovascular surgery, medical therapy was started. In the first year of follow-up, no events have been reported

The short-term supplementation of monacolin K improves the lipid and metabolic patterns of hypertensive and hypercholesterolemic subjects at low cardiovascular risk

A nutraceutical compound containing 10 mg of MK appeared to be safe, well tolerated and effective at improving lipid and glucose patterns

A novel model reference adaptive control approach investigation for power electronic converter applications

This paper demonstrates the viability and effectiveness of a novel adaptive control approach applied to power electronic converters. A methodology based on the formulation of a Lyapunov-based approach is showcased to represent the operation of a new adaptive controller for the regulation of two power converter topologies (Buck and Boost). The models of the Buck and Boost converter topologies include the parasitic parameters that represent the non-ideal components. The basic idea of the control approach is to demonstrate adaptive stabilization for the proposed non-linear system. The most important design specification to stabilize the system is to track the reference trajectory in such a way that the error on the output variable converges asymptotically to zero. This adaptation mechanism is explicitly designed so that the asymptotic stability of the equilibrium condition is guaranteed according to the Lyapunov theorem and sensitivity theory. The details of the design algorithm are explained in the paper. The proposed control approach has been compared to other Lyapunov-based control techniques proposed in literature for the same non-ideal converters. The results show that the proposed controller provides better level of robustness and performance than the other wellestablished Lyapunov based controllers. To verify the effectiveness of the controller in real time, a test bench has been set up with prototypes of both converters and the controller has been implemented using the Arduino microcontroller and the control system driven through the Matlab/Simulink platform

Application of Advanced Model Reference Adaptive Control for Bidirectional AC-DC Converters

Bidirectional AC-DC converters are used in many applications such as renewable energy systems, communication systems, and grid connection of electric vehicles. In this paper, a non-linear controller based on the Lyapunov-based model reference adaptive control approach is proposed for single-phase bidirectional AC-DC converters that incorporate active power factor correction circuits. The proposed controller dynamically adjusts the output power according to the grid conditions and user preferences while maintaining a nearly unitary power factor and a constant output DC voltage set as the reference value. The proposed controller also ensures the stability and robustness of the system under various operating conditions and disturbances. The performance of the proposed controller is compared with another Lyapunov-based control proposed in the literature to show that the proposed controller performs at least on par with the other controller in all aspects