Decay rate measurement of the first vibrationally excited state of MgH+^+ in a cryogenic Paul trap

We present a method to measure the decay rate of the first excited vibrational state of simple polar molecular ions being part of a Coulomb crystal in a cryogenic linear Paul trap. Specifically, we have monitored the decay of the $|\nu$=$1,J$=$1 \rangle_X$ towards the $|\nu$=$0,J$=$0 \rangle_X$ level in MgH$^+$ by saturated laser excitation of the $|\nu$=$0,J$=$2 \rangle_X$-$|\nu$=$1,J$=$1 \rangle_X$ transition followed by state selective resonance enhanced two-photon dissociation out of the $|\nu$=$0,J$=$2 \rangle_X$ level. The technique enables the determination of decay rates, and thus absorption strengths, with an accuracy at the few percent level.Comment: 5 pages, 4 figure

Turbulence-driven magnetic reconnection and the magnetic correlation length: observations from magnetospheric multiscale in Earth's magnetosheath

Turbulent plasmas generate a multitude of thin current structures that can be sites for magnetic reconnection. The Magnetospheric Multiscale (MMS) mission has recently enabled the detailed examination of such turbulent current structures in Earth's magnetosheath and revealed that a novel type of reconnection, known as electron-only reconnection, can occur. In electron-only reconnection, ions do not have enough space to couple to the newly reconnected magnetic fields, suppressing ion jet formation and resulting in thinner sub-proton-scale current structures with faster super-Alfvénic electron jets. In this study, MMS observations are used to examine how the magnetic correlation length (λC) of the turbulence, which characterizes the size of the large-scale magnetic structures and constrains the length of the current sheets formed, influences the nature of turbulence-driven reconnection. We systematically identify 256 reconnection events across 60 intervals of magnetosheath turbulence. Most events do not appear to have ion jets; however, 18 events are identified with ion jets that are at least partially coupled to the reconnected magnetic field. The current sheet thickness and electron jet speed have a weak anti-correlation, with faster electron jets at thinner current sheets. When ≲20 ion inertial lengths, as is typical near the sub-solar magnetosheath, a tendency for thinner current sheets and potentially faster electron jets is present. The results are consistent with electron-only reconnection being more prevalent for turbulent plasmas with relatively short λC and may be relevant to the nonlinear dynamics and energy dissipation in turbulent plasmas

The unacknowledged legacy

This paper presents a critical discussion of the treatment of mimetic art, and particularly poetry and the theatre, in the work of the Athenian philosopher Plato (427-347 BC). It centres on Plato's discussion of the corrupting powers of the arts in the Republic, and the implications that his fierce attack on poetry and theatre have for his construction of the ideal polity. The legacy of Platonic ideas in later elaborations of the corrupting power of the arts is discussed. Furthermore, the paper investigates the relationship between current debates on cultural policy and the Platonic idea that the transformative powers of the arts ought to be harnessed by the state to promote a just society. The conclusion thus reached is that “instrumental cultural policy”, rather then being a modern invention, was in fact first theorized precisely in Plato's Republic

MULTIPLE CURRENT SHEET SYSTEMS IN THE OUTER HELIOSPHERE: ENERGY RELEASE AND TURBULENCE

Accepted for publication in The Astrophysical Journal, March 21, 201

Pre-transplant CDKN2A expression in kidney biopsies predicts renal function and is a future component of donor scoring criteria

CDKN2A is a proven and validated biomarker of ageing which acts as an off switch for cell proliferation. We have demonstrated previously that CDKN2A is the most robust and the strongest pre-transplant predictor of post- transplant serum creatinine when compared to “Gold Standard” clinical factors, such as cold ischaemic time and donor chronological age. This report shows that CDKN2A is better than telomere length, the most celebrated biomarker of ageing, as a predictor of post-transplant renal function. It also shows that CDKN2A is as strong a determinant of post-transplant organ function when compared to extended criteria (ECD) kidneys. A multivariate analysis model was able to predict up to 27.1% of eGFR at one year post-transplant (p = 0.008). Significantly, CDKN2A was also able to strongly predict delayed graft function. A pre-transplant donor risk classification system based on CDKN2A and ECD criteria is shown to be feasible and commendable for implementation in the near future

Photoaffinity cross-linking and unnatural amino acid mutagenesis reveal insights into calcitonin gene-related peptide binding to the calcitonin receptor-like receptor/receptor activity-modifying protein 1 (CLR/RAMP1) complex

Calcitonin gene-related peptide (CGRP) binds to the complex of the calcitonin receptor-like receptor (CLR) with receptor activity-modifying protein 1 (RAMP1). How CGRP interacts with the transmembrane domain (including the extracellular loops) of this family B receptor remains unclear. In this study, a photoaffinity cross-linker, p-azido l-phenylalanine (azF), was incorporated into CLR, chiefly in the second extracellular loop (ECL2) using genetic code expansion and unnatural amino acid mutagenesis. The method was optimized to ensure efficient photolysis of azF residues near the transmembrane bundle of the receptor. A CGRP analogue modified with fluorescein at position 15 was used for detection of ultraviolet-induced cross-linking. The methodology was verified by confirming the known contacts of CGRP to the extracellular domain of CLR. Within ECL2, the chief contacts were I284 on the loop itself and L291, at the top of the fifth transmembrane helix (TM5). Minor contacts were noted along the lip of ECL2 between S286 and L290 and also with M223 in TM3 and F349 in TM6. Full length molecular models of the bound receptor complex suggest that CGRP sits at the top of the TM bundle, with Thr6 of the peptide making contacts with L291 and H295. I284 is likely to contact Leu12 and Ala13 of CGRP, and Leu16 of CGRP is at the ECL/extracellular domain boundary of CLR. The reduced potency, Emax, and affinity of [Leu16Ala]-human α CGRP are consistent with this model. Contacts between Thr6 of CGRP and H295 may be particularly important for receptor activation

Vasopressin-oxytocin–type signaling is ancient and has a conserved water homeostasis role in euryhaline marine planarians

Vasopressin/oxytocin (VP/OT)–related peptides are essential for mammalian antidiuresis, sociosexual behavior, and reproduction. However, the evolutionary origin of this peptide system is still uncertain. Here, we identify orthologous genes to those for VP/OT in Platyhelminthes, intertidal planarians that have a simple bilaterian body structure but lack a coelom and body-fluid circulatory system. We report a comprehensive characterization of the neuropeptide derived from this VP/OT-type gene, identifying its functional receptor, and name it the “platytocin” system. Our experiments with these euryhaline planarians, living where environmental salinities fluctuate due to evaporation and rainfall, suggest that platytocin functions as an “antidiuretic hormone” and also organizes diverse actions including reproduction and chemosensory-associated behavior. We propose that bilaterians acquired physiological adaptations to amphibious lives by such regulation of the body fluids. This neuropeptide-secreting system clearly became indispensable for life even without the development of a vascular circulatory system or relevant synapses

Glycomacropeptide:long-term use and impact on blood phenylalanine, growth and nutritional status in children with PKU

In phenylketonuria, casein glycomacropeptide (CGMP) requires modification with the addition of some essential and semi essential amino acids to ensure suitability as a protein substitute. The optimal amount and ratio of additional amino acids is undefined.AimA longitudinal, parallel, controlled study over 12months evaluating a CGMP (CGMP-AA2) formulation compared with phenylalanine-free L-amino acid supplements (L-AA) on blood Phe, Tyr, Phe:Tyr ratio, biochemical nutritional status and growth in children with PKU. The CGMP-AA2 contained 36mg Phe per 20g protein equivalent.MethodsChildren with PKU, with a median age of 9.2 y (5-16y) were divided into 2 groups: 29 were given CGMP-AA2, 19 remained on Phe-free L-AA. The CGMP-AA2 formula gradually replaced L-AA, providing blood Phe concentrations were maintained within target range. Median blood Phe, Tyr, Phe:Tyr ratio and anthropometry, were compared within and between the two groups at baseline, 26 and 52weeks. Nutritional biochemistry was studied at baseline and 26weeks only.ResultsAt the end of 52weeks only 48% of subjects were able to completely use CGMP-AA2 as their single source of protein substitute. At 52weeks CGMP-AA2 provided a median of 75% (30-100) of the total protein substitute with the remainder being given as L-AA. Within the CGMP-AA2 group, blood Phe increased significantly between baseline and 52weeks: [baseline to 26weeks; baseline Phe 270mol/L (170-430); 26weeks, Phe 300mol/L (125-485) p=0.06; baseline to 52weeks: baseline, Phe 270mol/L (170-430), 52weeks Phe 300mol/L (200-490),

THE THREE-DIMENSIONAL EVOLUTION OF ION-SCALE CURRENT SHEETS: TEARING AND DRIFT-KINK INSTABILITIES IN THE PRESENCE OF PROTON TEMPERATURE ANISOTROPY

We present the first three-dimensional hybrid simulations of the evolution of ion-scale current sheets, with an investigation of the role of temperature anisotropy and associated kinetic instabilities on the growth of the tearing instability and particle heating. We confirm the ability of the ion cyclotron and firehose instabilities to enhance or suppress reconnection, respectively. The simulations demonstrate the emergence of persistent three-dimensional structures, including patchy reconnection sites and the fast growth of a narrow-band drift-kink instability, which suppresses reconnection for thin current sheets with weak guide fields. Potential observational signatures of the three-dimensional evolution of solar wind current sheets are also discussed. We conclude that kinetic instabilities, arising from non-Maxwellian ion populations, are significant to the evolution of three-dimensional current sheets, and two-dimensional studies of heating rates by reconnection may therefore over-estimate the ability of thin, ion-scale current sheets to heat the solar wind by reconnection