Spinor condensates and light scattering from Bose-Einstein condensates

These notes discuss two aspects of the physics of atomic Bose-Einstein condensates: optical properties and spinor condensates. The first topic includes light scattering experiments which probe the excitations of a condensate in both the free-particle and phonon regime. At higher light intensity, a new form of superradiance and phase-coherent matter wave amplification were observed. We also discuss properties of spinor condensates and describe studies of ground--state spin domain structures and dynamical studies which revealed metastable excited states and quantum tunneling.Comment: 58 pages, 33 figures, to appear in Proceedings of Les Houches 1999 Summer School, Session LXXI

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

The effects of two calcium antagonists (nifedipine and verapamil) n renal function in sheep

The effects of the calcium antagonists, nifedipine and verapamil, were measured in five conscious Merino ewes at a dose rate of 0.5 microgram min-1 kg-1 for 60 min. Nifedipine caused a significant fall in mean arterial blood pressure (MABP) and central venous pressure (CVP) and an increase in heart rate (HR). There was no significant effect on renal vascular resistance (RVR) but, with the fall in MABP, renal plasma flow (RPF) decreased. There was a significant rise in glomerular filtration rate (GFR) and a small rise in filtration fraction (FF). Solute excretion, urine osmolality and solute-free water reabsorption (Tc, H2O) increased and urine flow (V) decreased. Plasma potassium (PK) and osmolality (Posm) decreased. Verapamil produced a similar fall in MABP and also had similar effects on the other parameters, except that in this case RVR was significantly reduced and there were significant increases in RPF and GFR. The rise in GFR which occurred regardless of the change in RPF, can account for the increase in solute excretion, although an effect of the calcium antagonists on tubular function cannot be excluded

The effects of an angiotensin blocker (saralasin) on kidney function in dehydrated sheep

Saralasin, an angiotensin II analogue and receptor blocker, was infused at 7 and 15 µg.min into dehydrated conscious Merino ewes. This caused mean arterial blood pressure, cardiac output, heart rate and renal vascular resistance to fall, and central venous pressure to rise. Renal plasma flow was unaffected but there were significant reductions in glomerular filtration rate, filtration fraction, urine flow, sodium and potassium excretion, solute clearance and solute‐free water reabsorption. It is suggested that saralasin produced these effects by inhibiting endogenous angiotensin II activity, and in particular by causing a reduction in renal post‐glomerular resistance. This in turn caused a fall in glomerular filtration rate and filtration fraction. While saralasin might have had effects on renal tubular function and perhaps on vasopressin secretion, the observed effects on renal function can be explained by the decrease in glomerular filtration rate and filtration fraction

HYPOTENSION‐INDUCED HYPOKALAEMIA IN SHEEP

Plasma K+ was measured in Merino ewes during 50‐90 min periods of hypotension induced by sodium nitroprusside, isoprenaline, verapamil or nifedipine. Doses were adjusted to produce falls in systemic blood pressure of approximately 20 mmHg. All of these drugs caused decreases in plasma K+ which could not be attributed to increased urinary excretion of K+. In all cases plasma renin activity increased during the hypotension. Plasma aldosterone concentration which was measured in some sodium nitroprusside experiments also increased during the hypotension. However, enhancement of the plasma renin activity and plasma aldosterone concentration responses by prior sodium depletion of the sheep by furosemide administration or suppression of the plasma renin activity and plasma aldosterone concentration responses by prior salt loading did not influence the magnitude of the hypotension‐induced hypokalaemia

CONVERTING‐ENZYME INHIBITION AND 1‐SARCOSINE‐8‐ISOLEUCINE‐ANGIOTENSIN II: EFFECTS ON RENAL FUNCTION IN THE DEHYDRATED SHEEP

The effect of a converting‐enzyme inhibitor (captopril) was studied in nine conscious dehydrated Merino ewes. Captopril (4 mg I.V. over 40 min) caused significant decreases in mean arterial blood pressure (M.A.B.P.), renal vascular resistance (R.V.R.) and filtration fraction, and increases in urine flow (V), sodium excretion, glomerular filtration rate (G.F.R.), renal plasma flow, solute clearance (Cosm), solute‐free water reabsorption (TC,H2O) and plasma renin activity (P.R.A.). None of these effects was observed when captopril was similarly administered to sheep pretreated with angiotensin II (AII) receptor blocker, l‐sarcosine‐8‐isoleucine‐AII (sarileucin). It is concluded that the effects of captopril were probably not due to bradykinin potentiation but rather to decreased levels of circulating AII. The effect of sarileucin itself was complex. It effectively blocked the pressor response to administered AII, but it also had an AII‐like effect indicated by a rise in R.V.R., and decreases in V, G.F.R., Cosm and TC,H2O. This apparent mixture of All agonist and antagonist properties probably accounts for the absence of any change in M.A.B.P. or P.R.A. during sarileucin administration