Mortality of emergency abdominal surgery in high-, middle- and low-income countries

Background: Surgical mortality data are collected routinely in high-income countries, yet virtually no low- or middle-income countries have outcome surveillance in place. The aim was prospectively to collect worldwide mortality data following emergency abdominal surgery, comparing findings across countries with a low, middle or high Human Development Index (HDI). Methods: This was a prospective, multicentre, cohort study. Self-selected hospitals performing emergency surgery submitted prespecified data for consecutive patients from at least one 2-week interval during July to December 2014. Postoperative mortality was analysed by hierarchical multivariable logistic regression. Results: Data were obtained for 10 745 patients from 357 centres in 58 countries; 6538 were from high-, 2889 from middle- and 1318 from low-HDI settings. The overall mortality rate was 1⋅6 per cent at 24 h (high 1⋅1 per cent, middle 1⋅9 per cent, low 3⋅4 per cent; P < 0⋅001), increasing to 5⋅4 per cent by 30 days (high 4⋅5 per cent, middle 6⋅0 per cent, low 8⋅6 per cent; P < 0⋅001). Of the 578 patients who died, 404 (69⋅9 per cent) did so between 24 h and 30 days following surgery (high 74⋅2 per cent, middle 68⋅8 per cent, low 60⋅5 per cent). After adjustment, 30-day mortality remained higher in middle-income (odds ratio (OR) 2⋅78, 95 per cent c.i. 1⋅84 to 4⋅20) and low-income (OR 2⋅97, 1⋅84 to 4⋅81) countries. Surgical safety checklist use was less frequent in low- and middle-income countries, but when used was associated with reduced mortality at 30 days. Conclusion: Mortality is three times higher in low- compared with high-HDI countries even when adjusted for prognostic factors. Patient safety factors may have an important role. Registration number: NCT02179112 (http://www.clinicaltrials.gov)

Degenerate Four-Wave Mixing Measurements Of High Order Nonlinearities In Semiconductors

We describe degenerate four-wave mixing experiments on ZnSe and CdTe semiconductor samples with picosecond laser pulses at wavelengths below the bandgap. Nonlinearities of third, fifth, and seventh order are observed and the mechanisms for each are identified. In all of our measurements, we observe a fast third order nonlinearity. For two-photon absorbers, this is attributed to contributions from both the real (refractive) and imaginary (absorptive) parts of the third-order susceptibility. Below the two-photon absorption edge, the nonlinearity is purely refractive. The higher order effects are due to carriers generated by multiphoton excitation. In ZnSe at 0.532 µm, carriers are generated by two-photon absorption such that a fifth order nonlinearity arises from the change in index due to these carriers, a sequential χ(3): χ(1) nonlinearity. From such measurements we determine the refractive index change per photoexcited carrier pair and the density dependence of the carrier diffusion coefficient. Analogous signals are observed in CdTe at 1.064 pm. The seventh order nonlinearity observed in ZnSe at 1.064 µm results from the refractive index contribution of carriers generated by three-photon absorption. © 1991 IEE

Polarization Dependent Four-Wave-Mixing And Two-Photon Coherence In Solids

Polarization dependent degenerate-four-wave-mixing experiments on semiconductors (ZnSe, CdS) and dielectrics (NaCl, PbF2) reveal the essential mechanisms of the bound-electronic χ(3). We show, for the first time, that the observed anomalous dispersion of the polarization dependent phase-conjugate reflectivity can be explained using a simple 3-band model. The near vanishing reflectivity in the two-photon coherence geometry is shown to be a consequence of the interference between transitions originating from heavy- and light-hole valence bands. We also present measurements on the polarization dichroism of the nonlinear refractive index (n2), in good agreement with this simple theory. Copyright 1995 IEE

Broadly Tunable Mid-Infrared Intracavity Difference-Frequency Laser

We generated diffraction-limited laser radiation that is continuously tunable from 3.1 to 4.4 µm by mixing the output from a Ti:sapphire laser with the intracavity field of a single-frequency, 1.064-mm Nd:YAG ring laser. A peak output power of 300 µW was observed near 3.2 µm at a Ti:sapphire input power of 300 mW. © 1995, Optical Society of America

Combined analysis of Belle and Belle II data to determine the CKM angle ϕ3 \phi_{3} using B+→D(KS0h−h+)h+B^+ \to D(K_{S}^0 h^- h^+) h^+ decays

We present a measurement of the Cabibbo-Kobayashi-Maskawa unitarity triangle angle ϕ$_{3}$ (also known as γ) using a model-independent Dalitz plot analysis of B$^{+}$ → D (${K}_S^0$h$^{+}$h$^{−}$)h$^{+}$, where D is either a D$^{0}$ or $\overline{D} ^{0}$ meson and h is either a π or K. This is the first measurement that simultaneously uses Belle and Belle II data, combining samples corresponding to integrated luminosities of 711 fb$^{−1}$ and 128 fb$^{−1}$, respectively. All data were accumulated from energy-asymmetric e$^{+}$e$^{−}$ collisions at a centre-of-mass energy corresponding to the mass of the Υ(4S) resonance. We measure ϕ$_{3}$ = (78.4 ± 11.4 ± 0.5 ± 1.0)°, where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is from the uncertainties on external measurements of the D-decay strong-phase parameters.[graphic not available: see fulltext