Thermal annealing of GaAs concentrator solar cells

Isochronal and isothermal annealing tests were performed on GaAs concentrator cells which were irradiated with electrons of various energies to fluences up to 1 x 10(exp 16) e/sq cm. The results include: (1) For cells irradiated with electrons from 0.7 to 2.3 MeV, recovery decreases with increasing electron energy. (2) As determined by the un-annealed fractions, isothermal and isochronal annealing produce the same recovery. Also, cells irradiated to 3 x 10(exp 15) or 1 x 10(exp 16) e/sq cm recover to similar un-annealed fractions. (3) Some significant annealing is being seen at 150 C although very long times are required

Apollo 17 neutron stratigraphy — Sedimentation and mixing in the lunar regolith

We have measured shifts in the isotopic a bundances of Gd and Sm in soils from the Apollo 17 deep drill stem and calculated the neutron fluence from these measurements. The measurements show two well defined regions of nearly constant fluence: (1) a thick deep section with a very large neutron fluence, and (2) a thinner shallow region with a small fluence. This depth dependence is most plausibly described by a model of rapid accumulation in the last 100–200 m.y., the layered structure reflecting accumulations of isotopically homogeneous source material. This interpretation is compatible with a variety of other characteristics of the soils, including the spallation produced126Xe normalized to target element abundances. An alternative model of deposition, followed by irradiation without mixing, followed by shallow mixing will quantitatively describe the data. The model yields an age of 1.25 AE for the bottom of the drill stem. This model was rejected because of the implausible requirement that the soils from the drill stem be accumulated from a source of unirradiated material. The uniformity of various properties of soils provides criteria for defining major stratigraphic intervals in the drill stem which differ from those identified by the Preliminary Examination Team. Neutron fluences measured on shallow and deep soils from all lunar landing sites have been normalized to irradiation in an arbitrary standard chemical environment. We infer from histograms of the normalized fluences that there is a distinct difference in neutron fluence between shallow and deep samples which implies a general vertical stratification of neutron fluence in the lunar regolith. The regolith can be divided into three vertical regions: (1) a well mixed surface layer, ∼100 g cm^(−2) thick, with an average fluence of 2.3 × 10^(16) n cm^(−2), (2) a poorly mixed zone extending from 100 g cm^(−2) to at least 500 g cm^(−2) with an average fluence of 3.5 × 10^(16) n cm^(−2), and (3) a deep layer of lightly irradiated materials (<10^(16) n cm^(−2)). Analysis of this stratification, using a vertical mixing model, indicates that the probability of mixing to several hundred g cm^(−2) is comparable to the probability of mixing to several kg cm^(−2). This is in contrast to the depth-cratering rate models which have been inferred from crater size frequency distributions using a power law. Alternatively, this discrepancy can be resolved if the true ^(157)Gd capture rate is 1/3 of the value calculated by Lingenfelteret al. (1972). The most plausible interpretation is that vertical mixing models are not an adequate description of relatively rare deep cratering events which result in significant lateral heterogeneity and addition of unirradiated material to the lunar surface

Should forest regeneration studies have more replications?

When it comes to testing for differences in seedling survival, researchers sometimes make a Type II statistical error (i.e. failure to reject a false null hypothesis) due to the inherent variability associated with survival in tree planting studies. For example, in one trial (with five replications) first-year survival of seedlings planted in October (42%) was not significantly different (alpha = 0.05) from those planted in December (69%). Did planting in a dry October truly have no effect on survival? Authors who make a Type II error might not be aware that as seedling survival decreases (down to an overall average of 50% survival), statistical power declines. As a result, the ability to declare an 8% difference as “significant†is very difficult when survival averages 90% or less.  We estimate that about half of regeneration trials (average survival of pines &lt;90%) cannot declare a 12% difference as statistically significant (alpha = 0.05).  When researchers realize their tree planting trials have low statistical power, they should consider using more replications.  Other ways to increase power include: (1) use a one-tailed test (2) use a potentially more powerful contrast test (instead of an overall treatment F-test) and (3) conduct survival trials under a roof

Calibration of Computational Models with Categorical Parameters and Correlated Outputs via Bayesian Smoothing Spline ANOVA

It has become commonplace to use complex computer models to predict outcomes in regions where data does not exist. Typically these models need to be calibrated and validated using some experimental data, which often consists of multiple correlated outcomes. In addition, some of the model parameters may be categorical in nature, such as a pointer variable to alternate models (or submodels) for some of the physics of the system. Here we present a general approach for calibration in such situations where an emulator of the computationally demanding models and a discrepancy term from the model to reality are represented within a Bayesian Smoothing Spline (BSS) ANOVA framework. The BSS-ANOVA framework has several advantages over the traditional Gaussian Process, including ease of handling categorical inputs and correlated outputs, and improved computational efficiency. Finally this framework is then applied to the problem that motivated its design; a calibration of a computational fluid dynamics model of a bubbling fluidized which is used as an absorber in a CO2 capture system

Increased Uniformity by Planting Clones Will Likely Have a Minimal Effect on Inventory Costs

When conducting inventories, reducing variability among tree diameters, heights, and ultimately volumes or biomass, can reduce the number of points/plots needed to obtain a desired level of precision. We present a simple analysis examining the potential reduction in discounted inventory costs when stand variability is decreased (via improved genetics and intensive management on a uniform soil). Sampling time might be reduced if the coefficient of variation in point volume/biomass estimates is reduced to 10% (versus 25% for genetically diverse stands). However, if this level of variability could be achieved (and depending on the desired probability and allowable percent error) discounted costs might be only reduced by $0.50 per acre for a single inventory (when a 15$20 to $30 per acre. On some very uniform sites, stands with low variability may only need one inventory plot per 25 acres. Although clones (in theory) might reduce variability, microsite conditions within a plantation will always produce variability among plots/points

Influence of Sorghum Wax, Glycerin, and Sorbitol on Physical Properties of Soy Protein Isolate Films

Sorghum wax, sorbitol, glycerin, and soy protein isolate (SPI) composite films were prepared. Effects of sorghum wax, sorbitol, and glycerin concentrations on various films were evaluated using response surface methodology. All independent variables significantly (P \u3c 0.05) affected film water vapor permeability (WVP), tensile strength (TS), elongation at break (E), total color difference, and total soluble matter (TSM). Increasing the sorghum wax concentration decreased WVP and E. As sorbitol content increased in the composite films, WVP and TS increased. Sorbitol had a critical point of 2–5 g/5 g SPI for low values of TSM. The addition of sorbitol contributed more to the properties of the film than did glycerin

In vitro activity of Iclaprim against Methicillin-resistant Staphylococcus aureus nonsusceptible to Daptomycin, Linezolid, or Vancomycin: A pilot study

Iclaprim is a bacterial dihydrofolate reductase inhibitor in Phase 3 clinical development for the treatment of acute bacterial skin and skin structure infections and hospital-acquired bacterial pneumonia caused by Gram-positive bacteria. Daptomycin, linezolid, and vancomycin are commonly used antibiotics for these indications. With increased selective pressure to these antibiotics, outbreaks of bacterial resistance to these antibiotics have been reported. This in vitro pilot study evaluated the activity of iclaprim against methicillin-resistant Staphylococcus aureus (MRSA) isolates, which were also not susceptible to daptomycin, linezolid, or vancomycin. Iclaprim had an MIC ≤ 1 µg/ml to the majority of MRSA isolates that were nonsusceptible to daptomycin (5 of 7 (71.4%)), linezolid (26 of 26 (100%)), or vancomycin (19 of 28 (66.7%)). In the analysis of time-kill curves, iclaprim demonstrated ≥ 3 log10 reduction in CFU/mL at 4–8 hours for tested strains and isolates nonsusceptible to daptomycin, linezolid, or vancomycin. Together, these data support the use of iclaprim in serious infections caused by MRSA nonsusceptible to daptomycin, linezolid, or vancomycin