Radiobiological parameters in a tumour control probability model for prostate cancer LDR brachytherapy.

To provide recommendations for the selection of radiobiological parameters for prostate cancer treatment planning. Recommendations were based on validation of the previously published values, parameter estimation and a consideration of their sensitivity within a tumour control probability (TCP) model using clinical outcomes data from low-dose-rate (LDR) brachytherapy. The proposed TCP model incorporated radiosensitivity (α) heterogeneity and a non-uniform distribution of clonogens. The clinical outcomes data included 849 prostate cancer patients treated with LDR brachytherapy at four Australian centres between 1995 and 2012. Phoenix definition of biochemical failure was used. Validation of the published values from four selected literature and parameter estimation was performed with a maximum likelihood estimation method. Each parameter was varied to evaluate the change in calculated TCP to quantify the sensitivity of the model to its radiobiological parameters. Using a previously published parameter set and a total clonogen number of 196 000 provided TCP estimates that best described the patient cohort. Fitting of all parameters with a maximum likelihood estimation was not possible. Variations in prostate TCP ranged from 0.004% to 0.67% per 1% change in each parameter. The largest variation was caused by the log-normal distribution parameters for α (mean, [Formula: see text], and standard deviation, σ α ). Based on the results using the clinical cohort data, we recommend a previously published dataset is used for future application of the TCP model with inclusion of a patient-specific, non-uniform clonogen density distribution which could be derived from multiparametric imaging. The reduction in uncertainties in these parameters will improve the confidence in using biological models for clinical radiotherapy planning.

Ultimate fracture load of cadaver proximal humeri correlates more strongly with mean combined cortical thickness than with areal cortical index, DEXA density, or canal-to-calcar ratio.

OBJECTIVES: This investigation sought to advance the work published in our prior biomechanical study (Journal of Orthopaedic Research, 2016). We specifically sought to determine whether there are additional easy-to-measure parameters on plain radiographs of the proximal humerus that correlate more strongly with ultimate fracture load, and whether a parameter resembling the Dorr strength/quality characterisation of proximal femurs can be applied to humeri. MATERIALS AND METHODS: A total of 33 adult humeri were used from a previous study where we quantified bone mineral density of the proximal humerus using radiographs and dual-energy x-ray absorptiometry (DEXA), and regional mean cortical thickness and cortical index using radiographs. The bones were fractured in a simulated backwards fall with the humeral head loaded at 2 mm/second via a frustum angled at 30° from the long axis of the bone. Correlations were assessed with ultimate fracture load and these new parameters: cortical index expressed in areas ("areal cortical index") of larger regions of the diaphysis; the canal-to-calcar ratio used analogous to its application in proximal femurs; and the recently described medial cortical ratio. RESULTS: The three new parameters showed the following correlations with ultimate fracture load: areal cortical index (r = 0.56, p < 0.001); canal-to-calcar ratio (r = 0.38, p = 0.03); and medial cortical ratio (r = 0.49, p < 0.005). These correlations were weaker when compared with those that we previously reported: mean cortical thickness of the proximal diaphysis versus ultimate fracture load (r = 0.71; p < 0.001); and mean density in the central humeral head versus ultimate fracture load (r = 0.70; p < 0.001). CONCLUSION: Simple-to-measure radiographic parameters of the proximal humerus reported previously are more useful in predicting ultimate fracture load than are areal cortical index, canal-to-calcar ratio, and medial cortical ratio.Cite this article: J. G. Skedros, C. S. Mears, W. Z. Burkhead. Ultimate fracture load of cadaver proximal humeri correlates more strongly with mean combined cortical thickness than with areal cortical index, DEXA density, or canal-to-calcar ratio. Bone Joint Res 2017;6:1-7. DOI: 10.1302/2046-3758.61.BJR-2016-0145.R1.

Incorporating model quality information in climate change detection and attribution studies.

In a recent multimodel detection and attribution (D&A) study using the pooled results from 22 different climate models, the simulated "fingerprint" pattern of anthropogenically caused changes in water vapor was identifiable with high statistical confidence in satellite data. Each model received equal weight in the D&A analysis, despite large differences in the skill with which they simulate key aspects of observed climate. Here, we examine whether water vapor D&A results are sensitive to model quality. The "top 10" and "bottom 10" models are selected with three different sets of skill measures and two different ranking approaches. The entire D&A analysis is then repeated with each of these different sets of more or less skillful models. Our performance metrics include the ability to simulate the mean state, the annual cycle, and the variability associated with El Niño. We find that estimates of an anthropogenic water vapor fingerprint are insensitive to current model uncertainties, and are governed by basic physical processes that are well-represented in climate models. Because the fingerprint is both robust to current model uncertainties and dissimilar to the dominant noise patterns, our ability to identify an anthropogenic influence on observed multidecadal changes in water vapor is not affected by "screening" based on model quality.

Identification of human-induced changes in atmospheric moisture content.

Data from the satellite-based Special Sensor Microwave Imager (SSM/I) show that the total atmospheric moisture content over oceans has increased by 0.41 kg/m(2) per decade since 1988. Results from current climate models indicate that water vapor increases of this magnitude cannot be explained by climate noise alone. In a formal detection and attribution analysis using the pooled results from 22 different climate models, the simulated "fingerprint" pattern of anthropogenically caused changes in water vapor is identifiable with high statistical confidence in the SSM/I data. Experiments in which forcing factors are varied individually suggest that this fingerprint "match" is primarily due to human-caused increases in greenhouse gases and not to solar forcing or recovery from the eruption of Mount Pinatubo. Our findings provide preliminary evidence of an emerging anthropogenic signal in the moisture content of earth's atmosphere.

Amplification of surface temperature trends and variability in the tropical atmosphere.

The month-to-month variability of tropical temperatures is larger in the troposphere than at Earth's surface. This amplification behavior is similar in a range of observations and climate model simulations and is consistent with basic theory. On multidecadal time scales, tropospheric amplification of surface warming is a robust feature of model simulations, but it occurs in only one observational data set. Other observations show weak, or even negative, amplification. These results suggest either that different physical mechanisms control amplification processes on monthly and decadal time scales, and models fail to capture such behavior; or (more plausibly) that residual errors in several observational data sets used here affect their representation of long-term trends.

Influence of satellite data uncertainties on the detection of externally forced climate change.

Two independent analyses of the same satellite-based radiative emissions data yield tropospheric temperature trends that differ by 0.1 degrees C per decade over 1979 to 2001. The troposphere warms appreciably in one satellite data set, while the other data set shows little overall change. These satellite data uncertainties are important in studies seeking to identify human effects on climate. A model-predicted "fingerprint" of combined anthropogenic and natural effects is statistically detectable only in the satellite data set with a warming troposphere. Our findings show that claimed inconsistencies between model predictions and satellite tropospheric temperature data (and between the latter and surface data) may be an artifact of data uncertainties.

Cryogenic high-resolution X-ray spectrometers for SR-XRF and microanalysis.

Experimental results are presented obtained with a cryogenically cooled high-resolution X-ray spectrometer based on a 141 x 141 micro m Nb-Al-Al(2)O(3)-Al-Nb superconducting tunnel junction (STJ) detector in an SR-XRF demonstration experiment. STJ detectors can operate at count rates approaching those of semiconductor detectors while still providing a significantly better energy resolution for soft X-rays. By measuring fluorescence X-rays from samples containing transition metals and low-Z elements, an FWHM energy resolution of 6-15 eV for X-rays in the energy range 180-1100 eV has been obtained. The results show that, in the near future, STJ detectors may prove very useful in XRF and microanalysis applications.

Social factors predicting postpartum choice of Norplant among African-American and non-Hispanic white adolescents.

PURPOSE: This study was designed to determine the factors associated with Norplant choice for postpartum teens. METHODS: A total of 151 teenagers, ages 12-20 years, who delivered at the Medical Center of Delaware from July to December 1992, were offered insertion of Norplant within 48 h postpartum. A structured interview was conducted in the postpartum period after nondirective counseling sessions including a physical demonstration using anatomical models of various contraceptive methods. Student's t-tests, chi-square, and multivariate analyses were used. RESULTS: Eighty-six teenagers were African-American (mean age = 17.3 +/- 1.9 years) and 65 non-Hispanic white (NHW) (mean age = 18.3 +/- 1.5 years). The NHW teenagers were older (p < 0.001); the African-American teenagers were more likely to have Medicaid (49% vs. 14%; p < 0.001) and to have one or more friends who use Norplant (62% vs. 34%; p < 0.001). In multivariate analyses, NHW teenagers were more likely to choose Norplant if they had discussed their choice with a parent or guardian [adjusted odds ratio (AOR) = 14.6, 95% confidence interval (CI), 2.12-100.57]; had Medicaid funding (AOR = 12.1; 95% (CI), 10.6-91.34); and had any friends who used Norplant (AOR = 6.3; 95% (CI), 1.38-28.40). However, for African-American teenagers, the strongest predictor for choice of Norplant was number of prior children delivered. After two deliveries, there was a better than four-fold likelihood (AOR = 4.8; 95% (CI), 1.47-15.94) that African-American teenagers would choose Norplant. For the African-American teenagers, parental discussion, Medicaid status, and friends' use of Norplant were not as important as family size, but far greater percentages of the African-American teenagers had access to Medicaid funding and peers who used Norplant. CONCLUSIONS: NHW and African-American teenagers choose Norplant for different reasons. Lack of funding may have been a barrier to choosing Norplant. Discussions with parents and friends have a positive influence on choosing Norplant for NHW teenagers. African-American teenagers were more likely than NHW to have Medicaid coverage, and more frequently choose Norplant if the current birth was their third child.

PIP: 151 youths, aged 12-20 years, who delivered at the Medical Center of Delaware from July to December 1992, were offered insertion of Norplant within 48 hours postpartum. These young women were subsequently interviewed to determine which factors are associated with choosing to accept or not accept Norplant. 86 Black teenagers of mean age 17.3 years and 65 non-Hispanic Whites of mean age 18.3 years participated. The White teenagers were significantly older, 49% of Blacks and 14% of Whites had Medicaid, and 62% of Blacks and 34% of Whites had one or more friends who use Norplant. In multivariate analyses, the White teens were more likely to choose Norplant if they had discussed their choice with a parent or guardian, if they received Medicaid funding, and if they had any friends who used Norplant. The strongest predictor for choice of Norplant among Black teens was the number of prior children delivered. After 2 deliveries, there was an almost 5-fold likelihood that Black teenagers would choose Norplant. For the Black teens, parental discussion, Medicaid status, and friends' use of Norplant were not as important as family size, but larger proportions of the Black teens had access to Medicaid funding and peers who used Norplant.

Soft x-ray performance of high-resolution superconducting spectrometers.

We are developing high-resolution, broad-band, superconducting X-ray spectrometers for applications in materials science, astrophysics and biophysics. These spectrometers are superconducting microcalorimeters based on superconducting tunnel junction sensors made from thin films of niobium and aluminum. The energy resolution of these spectrometers can be more than an order of magnitude better than that of the best Si(Li) or Ge(Li) detectors. We present results of recent measurements characterizing the performance of these detectors for X-ray energies from 70 eV to 500 eV, where the energy resolution ranged from 4 eV FWHM (at 70 eV) to 12 eV FWHM (at 500 eV).

Monoclonal antibody hapten radiopharmaceutical delivery.

One hundred micrograms of monoclonal antibody (MoAb) CHA255 with a binding constant Kb of 4 X 10(9) was complexed with indium-111 labelled BLEDTA II, BLEDTA IV, benzyl EDTA, and an EDTA conjugate of Fab. The 24-h tumour and organ distribution of BALB/c mice bearing KHJJ tumours was studied for each compound alone, the antibody complex, and 3 h following a chelate chase of the antibody complex. Whole body biological half-life was measured for 7 days with and without a chelate chase for each antibody complex. The 24-h whole body counts dropped 20 to 60% and blood concentration fell over 89% within 3 h of administering the chelate chase. Theoretical equivalent human organ doses were calculated from the 24-h organ concentrations, effective half-life, and MIRD 11 S values (absorbed dose per cumulated activity). Liver and spleen were the target organs, with the dose ranging from 0.50 to 3.91 rads mCi-1. The reduction in organ radiation dose varied up to 95% following the chelate chase. Rapid selective renal clearance of chelate labelled radiopharmaceuticals by competitive inhibition (chelate chase) of their reversible binding to monoclonal antibodies enhances tumour imaging and improves the radiation dosimetry.

Play: early and eternal.

A systematic 12-week investigation of development of play behavior was conducted with eight socially reared rhesus monkey infants. A new, basic and primary play form termed self-motion play or peragration was identified and examined. This behavior follows a human model which includes a wide range of pleasurable activities involving motion of the body through space, e.g., rocking, swinging, running, leaping, and water or snow skiing. It can be argued that self-motion play is the initial primate play form and because of its persistence constitutes a reinforcing agent for maintaining many complex patterns and even pastimes. Monkey self-motion play in the present study was divided into five separate patterns in order to compare the relative importance of social and individual peragration play, the role of apparatus and the overall developmental relationships between the different individual and social self-motion play patterns. The data showed that from 90 to 180 days of age self-motion play was independent of other forms of play, that individual self-motion play appeared earlier and with significantly greater increases in frequency than did social self-motion play, and that apparatus was a necessary component for significant increases in social self-motion play. Other findings were that self-motion play existed independent of locomotion and, though initiated by exploration, was separate from it. Therapeutic implications of self-motion play were discussed.