Close dat Eye : A Negro Lullaby

https://digitalcommons.library.umaine.edu/mmb-vp/4997/thumbnail.jp

Virtual Surgical Planning in Subscapular System Free Flap Reconstruction of Midface Defects.

OBJECTIVES: Reconstruction of the midface has many inherent challenges, including orbital support, skull base reconstruction, optimizing midface projection, separation of the nasal cavity and dental rehabilitation. Subscapular system free flaps (SF) have sufficient bone stock to support complex reconstruction and the option of separate soft tissue components. This study analyzes the effect of virtual surgical planning (VSP) in SF for midface on subsite reconstruction, bone segment contact and anatomic position. MATERIALS AND METHODS: Retrospective cohort of patients with midface defects that underwent SF reconstruction at a single tertiary care institution. RESULTS: Nine cases with VSP were compared to fourteen cases without VSP. VSP was associated with a higher number of successfully reconstructed subunits (5.9 vs 4.2, 95% CI of mean difference 0.31-3.04, p = 0.018), a higher number of successful bony contact between segments (2.2 vs 1.4, 95% CI of mean difference 0.0-1.6, p = 0.050), and a higher percent of segments in anatomic position (100% vs 71%, 95% CI of mean difference 2-55%, p = 0.035). When postoperative bone position after VSP reconstruction was compared to preoperative scans, the difference in anteroposterior, vertical and lateral projection compared to the preoperative \u27ideal\u27 bone position was82% of measurements. There were no flap losses. CONCLUSION: VSP may augment SF reconstruction of the midface by allowing for improved subunit reconstruction, bony segment contact and anatomically correct bone segment positioning. VSP can be a useful adjunct for complex midface reconstruction and the benefits should be weighed against cost

Monte Carlo Study of the Separation of Energy Scales in Quantum Spin 1/2 Chains with Bond Disorder

One-dimensional Heisenberg spin 1/2 chains with random ferro- and antiferromagnetic bonds are realized in systems such as $Sr_3 CuPt_{1-x} Ir_x O_6$. We have investigated numerically the thermodynamic properties of a generic random bond model and of a realistic model of $Sr_3 CuPt_{1-x} Ir_x O_6$ by the quantum Monte Carlo loop algorithm. For the first time we demonstrate the separation into three different temperature regimes for the original Hamiltonian based on an exact treatment, especially we show that the intermediate temperature regime is well-defined and observable in both the specific heat and the magnetic susceptibility. The crossover between the regimes is indicated by peaks in the specific heat. The uniform magnetic susceptibility shows Curie-like behavior in the high-, intermediate- and low-temperature regime, with different values of the Curie constant in each regime. We show that these regimes are overlapping in the realistic model and give numerical data for the analysis of experimental tests.Comment: 7 pages, 5 eps-figures included, typeset using JPSJ.sty, accepted for publication in J. Phys. Soc. Jpn. 68, Vol. 3. (1999

Scaling-up treatment of depression and anxiety: a global return on investment analysis

SummaryBackgroundDepression and anxiety disorders are highly prevalent and disabling disorders, which result not only in an enormous amount of human misery and lost health, but also lost economic output. Here we propose a global investment case for a scaled-up response to the public health and economic burden of depression and anxiety disorders.MethodsIn this global return on investment analysis, we used the mental health module of the OneHealth tool to calculate treatment costs and health outcomes in 36 countries between 2016 and 2030. We assumed a linear increase in treatment coverage. We factored in a modest improvement of 5% in both the ability to work and productivity at work as a result of treatment, subsequently mapped to the prevailing rates of labour participation and gross domestic product (GDP) per worker in each country.FindingsThe net present value of investment needed over the period 2016–30 to substantially scale up effective treatment coverage for depression and anxiety disorders is estimated to be US$147 billion. The expected returns to this investment are also substantial. In terms of health impact, scaled-up treatment leads to 43 million extra years of healthy life over the scale-up period. Placing an economic value on these healthy life-years produces a net present value of$310 billion. As well as these intrinsic benefits associated with improved health, scaled-up treatment of common mental disorders also leads to large economic productivity gains (a net present value of $230 billion for scaled-up depression treatment and$169 billion for anxiety disorders). Across country income groups, resulting benefit to cost ratios amount to 2·3–3·0 to 1 when economic benefits only are considered, and 3·3–5·7 to 1 when the value of health returns is also included.InterpretationReturn on investment analysis of the kind reported here can contribute strongly to a balanced investment case for enhanced action to address the large and growing burden of common mental disorders worldwide.FundingGrand Challenges Canada

Auger Recombination in Semiconductor Quantum Wells

The principal mechanisms of Auger recombination of nonequilibrium carriers in semiconductor heterostructures with quantum wells are investigated. It is shown for the first time that there exist three fundamentally different Auger recombination mechanisms of (i) thresholdless, (ii) quasi-threshold, and (iii) threshold types. The rate of the thresholdless Auger process depends on temperature only slightly. The rate of the quasi-threshold Auger process depends on temperature exponentially. However, its threshold energy essentially varies with quantum well width and is close to zero for narrow quantum wells. It is shown that the thresholdless and the quasi-threshold Auger processes dominate in narrow quantum wells, while the threshold and the quasi-threshold processes prevail in wide quantum wells. The limiting case of a three-dimensional (3D)Auger process is reached for infinitely wide quantum wells. The critical quantum well width is found at which the quasi-threshold and threshold Auger processes merge into a single 3D Auger process. Also studied is phonon-assisted Auger recombination in quantum wells. It is shown that for narrow quantum wells the act of phonon emission becomes resonant, which in turn increases substantially the coefficient of phonon-assisted Auger recombination. Conditions are found under which the direct Auger process dominates over the phonon-assisted Auger recombination at various temperatures and quantum well widths.Comment: 38 pages, 7 figure

The Percolation Signature of the Spin Glass Transition

Magnetic ordering at low temperature for Ising ferromagnets manifests itself within the associated Fortuin-Kasteleyn (FK) random cluster representation as the occurrence of a single positive density percolating network. In this paper we investigate the percolation signature for Ising spin glass ordering -- both in short-range (EA) and infinite-range (SK) models -- within a two-replica FK representation and also within the different Chayes-Machta-Redner two-replica graphical representation. Based on numerical studies of the $\pm J$ EA model in three dimensions and on rigorous results for the SK model, we conclude that the spin glass transition corresponds to the appearance of {\it two} percolating clusters of {\it unequal} densities.Comment: 13 pages, 6 figure

Quantum Monte Carlo Loop Algorithm for the t-J Model

We propose a generalization of the Quantum Monte Carlo loop algorithm to the t-J model by a mapping to three coupled six-vertex models. The autocorrelation times are reduced by orders of magnitude compared to the conventional local algorithms. The method is completely ergodic and can be formulated directly in continuous time. We introduce improved estimators for simulations with a local sign problem. Some first results of finite temperature simulations are presented for a t-J chain, a frustrated Heisenberg chain, and t-J ladder models.Comment: 22 pages, including 12 figures. RevTex v3.0, uses psf.te

A multi-scale comparison of modeled and observed seasonal methane emissions in northern wetlands

Wetlands are the largest global natural methane (CH4) source, and emissions between 50 and 70° N latitude contribute 10–30% to this source. Predictive capability of land models for northern wetland CH4 emissions is still low due to limited site measurements, strong spatial and temporal variability in emissions, and complex hydrological and biogeochemical dynamics. To explore this issue, we compare wetland CH4 emission predictions from the Community Land Model 4.5 (CLM4.5-BGC) with siteto regional-scale observations. A comparison of the CH4 fluxes with eddy flux data highlighted needed changes to the model’s estimate of aerenchyma area, which we implemented and tested. The model modification substantially reduced biases in CH4 emissions when compared with CarbonTracker CH4 predictions. CLM4.5 CH4 emission predictions agree well with growing season (May–September) CarbonTracker Alaskan regional-level CH4 predictions and sitelevel observations. However, CLM4.5 underestimated CH4 emissions in the cold season (October–April). The monthly atmospheric CH4 mole fraction enhancements due to wetland emissions are also assessed using the Weather Research and Forecasting-Stochastic Time-Inverted Lagrangian Transport (WRF-STILT) model coupled with daily emissions from CLM4.5 and compared with aircraft CH4 mole fraction measurements from the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) campaign. Both the tower and aircraft analyses confirm the underestimate of cold-season CH4 emissions by CLM4.5. The greatest uncertainties in predicting the seasonal CH4 cycle are from the wetland extent, coldseason CH4 production and CH4 transport processes. We recommend more cold-season experimental studies in highlatitude systems, which could improve the understanding and parameterization of ecosystem structure and function during this period. Predicted CH4 emissions remain uncertain, but we show here that benchmarking against observations across spatial scales can inform model structural and parameter improvements