Highly symmetric POVMs and their informational power

We discuss the dependence of the Shannon entropy of normalized finite rank-1 POVMs on the choice of the input state, looking for the states that minimize this quantity. To distinguish the class of measurements where the problem can be solved analytically, we introduce the notion of highly symmetric POVMs and classify them in dimension two (for qubits). In this case we prove that the entropy is minimal, and hence the relative entropy (informational power) is maximal, if and only if the input state is orthogonal to one of the states constituting a POVM. The method used in the proof, employing the Michel theory of critical points for group action, the Hermite interpolation and the structure of invariant polynomials for unitary-antiunitary groups, can also be applied in higher dimensions and for other entropy-like functions. The links between entropy minimization and entropic uncertainty relations, the Wehrl entropy and the quantum dynamical entropy are described.Comment: 40 pages, 3 figure

Revelations About Carotid Body Function Through its Pathological Role in Resistant Hypertension

Much recent attention has been given to the carotid body because of its potential role in cardiovascular disease states. One disease, neurogenic hypertension, characterised by excessive sympathetic activity, appears dependent on carotid body activity that may or may not be accompanied by sleep-disordered breathing. Herein, we review recent literature suggesting that the carotid body acquires tonicity in hypertension. We predict that carotid glomectomy will be a powerful way to temper excessive sympathetic discharge in diseases such as hypertension. We propose a model to explain that signalling from the ‘hypertensive’ carotid body is tonic, and hypothesise that there will be a sub-population of glomus cells that channel separately into reflex pathways controlling sympathetic motor outflows

Maturation of glomerular filtration rate in term-born neonates: an individual participant data meta-analysis.

Abstract Background: The evidence from individual studies to support the maturational pattern of glomerular filtration rate (GFR) in healthy term-born neonates is inconclusive. We performed an individual participant data (IPD) meta-analysis of reported measured GFR (mGFR) data aimed to establish GFR reference values in the first month of life. As a secondary objective, we aimed to optimize neonatal creatinine-based GFR estimations in clinical care. Methods: We identified studies reporting mGFR measured by exogenous markers or creatinine clearance (CrCL) in healthy term-born neonates through searching the Pubmed and ClinicalTrials.gov databases. The relationship between postnatal age and individual clearance was investigated using cubic splines with generalized additive linear mixed models. From our reference values, we estimated an updated coefficient for the Schwartz equation (eGFR(ml/min/1.73m2)=(k*height (cm))/serum creatinine(mg/dl)). Results: Fifty out of 1521 screened articles reported mGFR in healthy term-born neonates, and we analyzed 1041 mGFR values from 944 neonates. IPD were available for 367 neonates and the other 577 neonates were represented by 44 aggregated data points as means/medians per cohortgroup. GFR doubled in the first five days after birth from 19.6 (95% CI 14.7;24.6) ml/min/1.73m2 to 40.6 (95% CI 36.7;44.5) ml/min/1.73m2, then more gradually increased to 59.4 (95% CI 45.9;72.9) ml/min/1.73m2 by four weeks of age. A coefficient of 0.31 to estimate GFR best fitted the data. Conclusions: These reference values for healthy term newborns show a biphasic increase in GFR with the largest increase between days 1 and 5. Our mGFR reference values and updated coefficient for the Schwartz equation can help identify acute kidney injury or augmented renal clearance altered GFR in term-born neonates