On the physical nonexistence of signals going backwards in time, and quantum mechanics

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Effectiveness and safety of the angiotensin II antagonist irbesartan in children with chronic kidney diseases

Background: Studies in adults with chronic kidney diseases demonstrate that the orally available angiotensin II antagonist irbesartan reduces arterial pressure and pathological proteinuria, mostly with an excellent tolerability profile. Little information is available on irbesartan in childhood. Methods: A total of 44 pediatric outpatients with chronic kidney disease (27 male and 17, aged 3.7 to 18 years, median 10 years) were given irbesartan once a day during 18 weeks for arterial hypertension (N = 23), proteinuria (N = 8), or both (N = 13). Results: In patients with hypertension, the use of irbesartan 4.1 (3.1-5.3) mg/kg body weight daily (median and interquartile range) was associated with a decrease (P < .005) in arterial pressure by 17 (13-22)/10 (7-12) mm Hg. In patients with overt proteinuria the urinary protein excretion decreased (P < .01) during treatment with irbesartan (2.9 [2.0-4.8] mg/kg body weight) by 52 (0-75) mg/[m2 × h]), whereas plasma albumin increased (P < .05) by 4 (1-5) g/L. The frequency of abdominal pain, constipation, cough, diarrhea, dizziness, edema, fatigue, headache, insomnia, myalgia, orthostasis, and rash was similar before and with irbesartan. Plasma sodium slightly decreased, whereas plasma potassium increased, with irbesartan (P < .01). Conclusions: In pediatric patients with chronic kidney diseases, irbesartan given once a day for 18 weeks significantly reduces arterial pressure and proteinuria, with an excellent tolerability and side effect profile. Am J Hypertens 2002;15:1057-1063 © 2002 American Journal of Hypertension, Lt

Science Communication: Stakeholder perceptions of Real-time Incentive Fisheries Management

Peer-reviewedIn these changing times, with political and environmental uncertainty surrounding us, fisheries management needs to become more adaptive in order to respond to the changes in our natural environment and changing management frameworks. Based on close to real-time information updates, and harnessing modern technology, Real-Time Incentive (RTI) fisheries management is designed to evolve with the fish stocks, enabling managers to respond more quickly and efficiently to management issues as they arise. Through the use of a credit system that makes use of regularly updated fine-scale information, incentives can be incorporated as rewards to encourage desirable actions such as data collection or ‘fishing-for-litter’ activities. However, in order for a new system such as this to be useful and become accepted, stakeholders must be involved in the development and design process. This paper details the consultative process carried out with Irish demersal fishery stakeholders in an effort to identify their likes and dislikes of the system, and work towards tailoring the RTI system into a practical solution that works for them. In this process, we achieved a detailed understanding of the fishery, the complexity of the system, and the challenges faced by the stakeholders, all of which must be considered when attempting to implement a new management system such as RTI. A range of proposals were made by stakeholders, including new ideas for the future development of the RTI system. Most striking were the numerous ideas and approaches to tackling key issues currently facing the industry, many of which also have relevance to existing fisheries management. Given the freedom and support to do so, fishing industry stakeholders are eager to contribute to solving many of their own problems.Funded by SFI Investigator Programme (grant number 14/IA/2549

Time-like flows of energy-momentum and particle trajectories for the Klein-Gordon equation

The Klein-Gordon equation is interpreted in the de Broglie-Bohm manner as a single-particle relativistic quantum mechanical equation that defines unique time-like particle trajectories. The particle trajectories are determined by the conserved flow of the intrinsic energy density which can be derived from the specification of the Klein-Gordon energy-momentum tensor in an Einstein-Riemann space. The approach is illustrated by application to the simple single-particle phenomena associated with square potentials.Comment: 14 pages, 11 figure

Jamming non-local quantum correlations

We present a possible scheme to tamper with non-local quantum correlations in a way that is consistent with relativistic causality, but goes beyond quantum mechanics. A non-local ``jamming" mechanism, operating within a certain space-time window, would not violate relativistic causality and would not lead to contradictory causal loops. The results presented in this Letter do not depend on any model of how quantum correlations arise and apply to any jamming mechanism.Comment: 10 pp, LaTe

Time on a Rotating Platform

Traditional clock synchronisation on a rotating platform is shown to be incompatible with the experimentally established transformation of time. The latter transformation leads directly to solve this problem through noninvariant one-way speed of light. The conventionality of some features of relativity theory allows full compatibility with existing experimental evidence.Comment: 12 pages, Latex, no figure. Copies available at [email protected] accepted for publication in Found. Phys. Let

Controlling spin relaxation with a cavity

Spontaneous emission of radiation is one of the fundamental mechanisms by which an excited quantum system returns to equilibrium. For spins, however, spontaneous emission is generally negligible compared to other non-radiative relaxation processes because of the weak coupling between the magnetic dipole and the electromagnetic field. In 1946, Purcell realized that the spontaneous emission rate can be strongly enhanced by placing the quantum system in a resonant cavity -an effect which has since been used extensively to control the lifetime of atoms and semiconducting heterostructures coupled to microwave or optical cavities, underpinning single-photon sources. Here we report the first application of these ideas to spins in solids. By coupling donor spins in silicon to a superconducting microwave cavity of high quality factor and small mode volume, we reach for the first time the regime where spontaneous emission constitutes the dominant spin relaxation mechanism. The relaxation rate is increased by three orders of magnitude when the spins are tuned to the cavity resonance, showing that energy relaxation can be engineered and controlled on-demand. Our results provide a novel and general way to initialise spin systems into their ground state, with applications in magnetic resonance and quantum information processing. They also demonstrate that, contrary to popular belief, the coupling between the magnetic dipole of a spin and the electromagnetic field can be enhanced up to the point where quantum fluctuations have a dramatic effect on the spin dynamics; as such our work represents an important step towards the coherent magnetic coupling of individual spins to microwave photons.Comment: 8 pages, 6 figures, 1 tabl