Line narrowing of AgGaSe2 optical parametric oscillator by injection seeding

Solid-state lasers are developed for atmospheric applications. Optical parametric oscillators (OPO) are being investigated as sources of tunable radiation in the 2.5-12 micron range where development of conventional lasers is subject to numerous difficulties. Parametric oscillation is a nonlinear optical technique for converting laser output to longer wavelengths. Incident photons, typically from a pulsed pump laser, are converted into two photons of longer wavelength, while satisfying energy conservation. The particular split of energy is determined by momentum conservation; the wavelength of interest is usually selected by angle orientation of the nonlinear material with respect to the direction of propagation of the pump beam. An OPO based on AgGaSe2 was considered

Proctolin and an Endogenous Proctolin-Like Peptide Enhance the Contractility of the Limulus Heart

Synthetic proctolin increases the force but not the rate of heart contractions of Limulus in a time- and dose-dependent manner. The threshold of this effect is 3 × 10−10M and the ED50 is approximately 10−8M. At concentrations up to 10−7 M, proctolin has no effect on the rhythmic electrical activity of the isolated cardiac ganglion, and it does not change the simple and compound postsynaptic potentials recorded at the cardiac neuromuscular junction. Proctolin acts directly on the cardiac muscle fibres. Electrically stimulated myocardia show a proctolin-induced increase in contraction amplitude with the same concentration dependence as the intact heart. A compound with an apparent molecular weight of 700–800 occurs in the Limulus nervous system, particularly in the cardiac ganglion. This compound resembles proctolin in being heat-stable, resistant to trypsin and chymotrypsin cleavage, and losing activity in a time-dependent manner in response to treatment with leucine aminopeptidase or pronase. This peptide induces spontaneous contractions and a contracture of the cockroach hindgut in a manner similar to proctolin. Moreover, the Limulus inotropic peptide, like proctolin, increases the force of contraction of the Limulus heart without affecting beat frequency. It is concluded that an endogenous, proctolin-like peptide is an inotropic modulator of the Limulus heart, acting directly on the muscle fibres and not affecting cardiac ganglion activity

Neurohormonal modulation of the Limulus heart: amine actions on neuromuscular transmission and cardiac muscle

The responses of Limulus cardiac neuromuscular junctions and cardiac muscle cells to four endogenous amines were determined in order to identify the cellular targets underlying amine modulation of heartbeat amplitude. The amines increased the amplitude of the Limulus heartbeat, with dopamine (DA) being more potent than octopamine, epinephrine or norepinephrine. The effect of DA on heartbeat amplitude was not blocked by phentolamine. DA enhanced the contractility of deganglionated heart muscle, with time course and dose-dependence similar to its effect on the intact heart. The amines also enhanced neuromuscular transmission, with time course and dose-dependence similar to their effects upon the intact heart. The amplitude of unitary excitatory junction potentials (EJPs) and frequency of miniature excitatory junction potentials (mEJPs) were increased by DA, while mEJP amplitude was unchanged. Thus DA, and probably the other amines, had a presynaptic effect. Combined actions upon cardiac muscle and cardiac neuromuscular transmission account for the ability of these amines to increase the amplitude of the Limulus heartbeat

A Bayesian analysis of the 27 highest energy cosmic rays detected by the Pierre Auger Observatory

It is possible that ultra-high energy cosmic rays (UHECRs) are generated by active galactic nuclei (AGNs), but there is currently no conclusive evidence for this hypothesis. Several reports of correlations between the arrival directions of UHECRs and the positions of nearby AGNs have been made, the strongest detection coming from a sample of 27 UHECRs detected by the Pierre Auger Observatory (PAO). However, the PAO results were based on a statistical methodology that not only ignored some relevant information (most obviously the UHECR arrival energies but also some of the information in the arrival directions) but also involved some problematic fine-tuning of the correlation parameters. Here we present a fully Bayesian analysis of the PAO data (collected before 2007 September), which makes use of more of the available information, and find that a fraction F_AGN = 0.15^(+0.10)_(-0.07) of the UHECRs originate from known AGNs in the Veron-Cetty & Veron (VCV) catalogue. The hypothesis that all the UHECRs come from VCV AGNs is ruled out, although there remains a small possibility that the PAO-AGN correlation is coincidental (F_AGN = 0.15 is 200 times as probable as F_AGN = 0.00).Comment: MNRAS, accepted; 8 pages, 7 figure

The management of depressed elderly care recipients : family perspectives on the skills of professional carers

Recent studies have identified high levels of depression among older people, both those in their own homes and those in residential care. With the world\u27s population ageing, it is timely for health service providers to consider how the escalating population of depressed elderly people will be managed. Although treating general practitioners may be the health professionals most expected to detect, treat, and monitor depression among the elderly, professional carers are well placed to assist in the detection and monitoring of the disorder. This study conducted individual interviews with 15 family members of depressed aged-care recipients to determine their perceptions of the skills and knowledge of depression of professional carers. Family members reported that carers are more likely to avoid than engage with their clients about depressive symptomatology and do not communicate their concerns with managers or general practitioners (GPs). Family members believed that, in general, professional carers were undertrained in these areas. The implications of these findings for health service planning and staff training are discussed. <br /

On the Green function of linear evolution equations for a region with a boundary

We derive a closed-form expression for the Green function of linear evolution equations with the Dirichlet boundary condition for an arbitrary region, based on the singular perturbation approach to boundary problems.Comment: 9 page

Fenretinide mediated retinoic acid receptor signalling and inhibition of ceramide biosynthesis regulates adipogenesis, lipid accumulation, mitochondrial function and nutrient stress signalling in adipocytes and adipose tissue

Fenretinide (FEN) is a synthetic retinoid that inhibits obesity and insulin resistance in high-fat diet (HFD)-fed mice and completely prevents 3T3-L1 pre-adipocyte differentiation. The aim of this study was to determine the mechanism(s) of FEN action in 3T3-L1 adipocytes and in mice. We used the 3T3-L1 model of adipogenesis, fully differentiated 3T3-L1 adipocytes and adipose tissue from HFD-induced obese mice to investigate the mechanisms of FEN action. We measured expression of adipogenic and retinoid genes by qPCR and activation of nutrient-signalling pathways by western blotting. Global lipid and metabolite analysis was performed and specific ceramide lipid species measured by liquid chromatography-mass spectrometry. We provide direct evidence that FEN inhibits 3T3-L1 adipogenesis via RA-receptor (RAR)-dependent signaling. However, RARα antagonism did not prevent FEN-induced decreases in lipid levels in mature 3T3-L1 adipocytes, suggesting an RAR-independent mechanism. Lipidomics analysis revealed that FEN increased dihydroceramide lipid species 5- to 16-fold in adipocytes, indicating an inhibition of the final step of ceramide biosynthesis. A similar blockade in adipose tissue from FEN-treated obese mice was associated with a complete normalisation of impaired mitochondrial β-oxidation and tricarboxylic acid cycle flux. The FEN catabolite, 4-oxo-N-(4-hydroxyphenyl)retinamide (4-OXO), also decreased lipid accumulation without affecting adipogenesis. FEN and 4-OXO (but not RA) treatment additionally led to the activation of p38-MAPK, peIF2α and autophagy markers in adipocytes. Overall our data reveals FEN utilises both RAR-dependent and -independent pathways to regulate adipocyte biology, both of which may be required for FEN to prevent obesity and insulin resistance in vivo