Abstract
Synthetic crystal lattices provide ideal environments for simulating and exploring the band structure of solid-state materials in clean and controlled experimental settings. Physical ...realisations have, so far, dominantly focused on implementing irreversible patterning of the system, or interference techniques such as optical lattices of cold atoms. Here, we realise reprogrammable synthetic band-structure engineering in an all optical exciton-polariton lattice. We demonstrate polariton condensation into excited states of linear one-dimensional lattices, periodic rings, dimerised non-trivial topological phases, and defect modes utilising malleable optically imprinted non-Hermitian potential landscapes. The stable excited nature of the condensate lattice with strong interactions between sites results in an actively tuneable non-Hermitian analogue of the Su-Schrieffer-Heeger system.
Abstract
One of the recently established paradigms in condensed matter physics is examining a system’s behaviour in artificial potentials, giving insight into phenomena of quantum fluids in ...hard-to-reach settings. A prominent example is the matter-wave scatterer lattice, where high energy matter waves undergo transmission and reflection through narrow width barriers leading to stringent phase matching conditions with lattice band formation. In contrast to evanescently coupled lattice sites, the realisation of a scatterer lattice for macroscopic matter-wave fluids has remained elusive. Here, we implement a system of exciton-polariton condensates in a non-Hermitian Lieb lattice of scatterer potentials. By fine tuning the lattice parameters, we reveal a nonequilibrium phase transition between distinct regimes of polariton condensation: a scatterer lattice of gain guided polaritons condensing on the lattice potential maxima, and trapped polaritons condensing in the potential minima. Our results pave the way towards unexplored physics of non-Hermitian fluids in non-stationary mixtures of confined and freely expanding waves.
BACKGROUND:Acute kidney injury (AKI) is a serious complication after major surgical procedures. We examined the incidence, risk factors, and mortality of patients who sustained AKI after abdominal ...surgery in a large population-based cohort.
METHODS:All patients who underwent open and laparoscopic abdominal surgery (excluding genitourinary and abdominal vascular procedures), between 2007 and 2014 at the University Hospital in Reykjavik were identified and their perioperative serum creatinine (SCr) measurements used to identify AKI after surgery employing the Kidney DiseaseImproving Global Outcome (KDIGO) criteria. Risk factors were evaluated using multivariate logistic regression analysis and 30-day mortality compared with a propensity score–matched control group.
RESULTS:During the 8-year period, a total of 11,552 abdominal surgeries were performed on 10,022 patients. Both pre- and postoperative SCr measurements were available for 3902 (33.8%) of the surgical cases. Of these, 264 (6.8%) were complicated by AKI; 172 (4.4%), 49 (1.3%), and 43 (1.1%) were classified as KDIGO stages 1, 2 and 3, respectively. The overall incidence of AKI for patients with available SCr values was 67.7 (99% confidence interval CI, 57.7–78.6) per 1000 surgeries. In logistic regression analysis, independent risk factors for AKI were female sex (odds ratio OR = 0.68; 99% CI, 0.47–0.98), hypertension (OR = 1.75; 99% CI, 1.10–2.74), preoperative chronic kidney disease (OR= 1.68; 99% CI, 1.12–2.50), ASA physical status classification of IV (OR = 9.48; 99% CI, 3.66–29.2) or V (OR = 21.4; 99% CI, 5.28–93.6), and reoperation (OR = 4.30; 99% CI, 2.36–7.70). Patients with AKI had greater 30-day mortality (18.2% vs 5.3%; P < 0.001) compared with propensity score–matched controls.
CONCLUSIONS:AKI is an important complication of abdominal surgery. In addition to sex, hypertension, and chronic kidney disease, ASA physical status classification is an independent predictor of AKI. Individuals who develop AKI have substantially worse short-term outcomes, including higher 30-day mortality, even after correcting for multiple patient- and procedure-related risk factors.
It is shown that a condensate of microcavity exciton-polaritons exhibits bistability between its two orthogonal linearly polarized components for varying nonresonant excitation power. A non-Hermitian ...splitting of these components results in two parity-symmetric fixed-point solutions of opposite polarization, making up the hysteresis branches. These solutions correspond to the lowest threshold linearly polarized mode, which dominates at low pump powers, and a cross-polarized mode, which appears due to nonlinear pinning at higher excitation powers. The spin symmetry of the solutions extends the nonresonant bistable operation of polariton condensates to the entire equatorial plane of the Poincaré sphere. The results pave the way towards development of tailored bistable, linearly polarized, coherent sources of light.
We demonstrate deterministic control of the nearest and next-nearest neighbor coupling in the unit cell of a square lattice of microcavity exciton-polariton condensates. We tune the coupling in a ...continuous and reversible manner by optically imprinting potential barriers of variable height, in the form of spatially localized incoherent exciton reservoirs that modify the particle flow between condensates. By controlling the couplings in a 2×2 polariton cluster, we realize ferromagnetic, antiferromagnetic, and paired ferromagnetic phases and demonstrate the potential scalability of the system.
Introduction
The aim of this study was to assess population‐based changes in incidence, treatment, and in short‐ and long‐term survival of patients with acute respiratory distress syndrome (ARDS) ...over 23 years.
Materials and Methods
Analysis of all patients in Iceland who fulfilled the consensus criteria for ARDS in 1988–2010. Demographic variables, Acute Physiology and Chronic Health Evaluation II (APACHE II) scores and ventilation parameters were collected from hospital charts.
Results
The age‐standardised incidence of ARDS during the study period was 7.2 cases per 100,000 person‐years and was increased by 0.2 cases per year (P < 0.001). The most common causes of ARDS were pneumonia (29%) and sepsis (29%). The use of pressure‐controlled ventilation became almost dominant from 1993. The peak inspiratory pressure (PIP) has significantly decreased (−0.5 cmH2O/year), but the peak end‐expiratory pressure (PEEP) has increased (0.1 cmH2O/year) during the study period. The hospital mortality decreased by 1% per year (P = 0.03) during the study period, from 50% in 1988–1992 to 33% in 2006–2010. A multivariable logistic regression model revealed that higher age and APACHE II score increased the odds of hospital mortality, while a higher calendar year of diagnosis reduced the odds of mortality. This was unchanged when dominant respiratory treatment, PIP and PEEP were added to the model. The 10‐year survival of ARDS survivors was 68% compared with 90% survival of a reference population (P < 0.001).
Conclusion
The incidence of ARDS has almost doubled, but hospital mortality has decreased during the 23 years of observation. The 10‐year survival of ARDS survivors is poor compared with the reference population.
We demonstrate that multiply coupled spinor polariton condensates can be optically tuned through a sequence of spin-ordered phases by changing the coupling strength between nearest neighbors. For ...closed four-condensate chains these phases span from ferromagnetic (FM) to antiferromagnetic (AFM), separated by an unexpected crossover phase. This crossover phase is composed of alternating FM-AFM bonds. For larger eight-condensate chains, we show the critical role of spatial inhomogeneities and demonstrate a scheme to overcome them and prepare any desired spin state. Our observations thus demonstrate a fully controllable nonequilibrium spin lattice.
The aim of this study was to compare the effects of goal-directed colloid fluid therapy with goal-directed crystalloid and restricted crystalloid fluid therapy on healthy and perianastomotic colon ...tissue in a pig model of colon anastomosis surgery.
Pigs (n = 27, 9 per group) were anesthetized and mechanically ventilated. A hand-sewn colon anastomosis was performed. The animals were subsequently randomized to one of the following treatments: R-RL group, 3 ml x kg(-1) x h(-1) Ringer lactate (RL); GD-RL group, 3 ml x kg(-1) x h(-1) RL + bolus 250 ml of RL; GD-C group, 3 ml x kg(-1) x h(-1) RL + bolus 250 ml of hydroxyethyl starch (HES 6%, 130/0.4). A fluid bolus was administered when mixed venous oxygen saturation dropped below 60%. Intestinal tissue oxygen tension and microcirculatory blood flow were measured continuously.
After 4 h of treatment, tissue oxygen tension in healthy colon increased to 150 +/- 31% in group GD-C versus 123 +/- 40% in group GD-RL versus 94 +/- 23% in group R-RL (percent of postoperative baseline values, mean +/- SD; P < 0.01). Similarly perianastomotic tissue oxygen tension increased to 245 +/- 93% in the GD-C group versus 147 +/- 58% in the GD-RL group and 116 +/- 22% in the R-RL group (P < 0.01). Microcirculatory flow was higher in group GD-C in healthy colon.
Goal-directed colloid fluid therapy significantly increased microcirculatory blood flow and tissue oxygen tension in healthy and injured colon compared to goal-directed or restricted crystalloid fluid therapy.
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