Extent Of Overestimation Research Articles

Relative and absolute difference in soil organic carbon stocks in grassland soils in Ireland: Impact of rock fragments, bulk density and calculation methods

On-farm management measures can sequester carbon by removing carbon dioxide from the atmosphere and storing it securely for long periods, in our soils. Estimates of soil organic carbon (SOC) stocks differ by calculation methods in terms of how they account for the coarse >2 mm fraction (i.e. rock fragments) of the soil. Irish grassland soils have variable volumetric stone contents and the extent of overestimation is unknown. Without best practice guidance, calculations of SOC in these soils are vulnerable to overestimation. The objectives of the present study for grassland soils in Ireland were to: 1) calculate mean SOC stocks using different methods by soil horizon and volumetric stone content class; 2) highlight relative differences in SOC stocks between these calculation methods and 3) compare normalised layer (Ly, fixed depth) versus horizon (Hz) type derived sampling data in terms of SOC stocks, to establish a best practice standardised sampling protocol. Five methods (M, 1–3 overestimate SOC stocks, whereas 4–5 are equivalent and are closest to reality) to calculate SOC stocks were used in combination with three soil databases i.e. Irish Soil Information System (I-SIS), the Heavy Soils Programme (HSP) and the Soil Quality Assessment Research Project (SQUARE). Objectives 1 and 2 were assessed using all three databases across methods, whereas objective 3 used the SQUARE database and M4. These data were sorted into volumetric stone content (%) classes (< 5%, 5–10%, 10–20%, 20–30% and > 30%) and sampling horizon (O, A, E, A/B, B, B/C, and C) with SOC stocks calculated using M1–5 equations. Results confirmed the high volumetric stone content assumption of grassland soils in Ireland (exception O horizons). Volumetric stone contents ranged from 0% to 36% for all horizons. When M1–5 are considered the average relative difference in SOC stocks between M1 and M5 was 18.9% (max: 388%), M2 and M5 was 7.7% (max: 60.7%) and M3 and M5 was 8.9 (max: 310%). In terms of Ly versus Hz sampling, no significant differences were found for the A horizons sampled. However, in Ireland, best practice should still utilise elements from both Ly (using an auger to get fixed depth soil samples; analysed for organic C) and Hz (using a soil profile pit to extract representative BD cores and to gather bulk samples for volumetric stone content analysis) approaches in the field. Laboratory methods used must fit with the needs and assumptions of equations M4/5 to calculate SOC stocks (thereby minimising overestimation and indeed underestimation).

When Expectation Isn’t Reality: Racial Disparities in Overestimation and STEM Attrition Among First-Year Students in College

ABSTRACT Existing research indicates that underrepresented-in-STEM racially minoritized students with similar academic preparation are less likely than their counterparts to persist in STEM, raising the question of factors that may contribute to racial disparities in STEM participation beyond academic preparation. We extend the current literature by first examining race-based differences in what students expect to receive and their actual grades in introductory STEM college courses, a phenomenon termed as overestimation. Then, we assess whether overestimation differentially influences STEM interest and persistence in college. Findings indicate that first-year STEM students tend to overestimate their performance in general, and the extent of overestimation is more pronounced among racially minoritized students. Subsequent analyses indicate that students who overestimate are more likely to switch out of STEM, net of academic preparation. Results from regression models suggest that race-based differences in overestimation can be explained by pre-college academic and contextual factors, most notably the high school a student attended.

The accuracy of pulse oximetry in measuring oxygen saturation by levels of skin pigmentation: a systematic review and meta-analysis

BackgroundDuring the COVID-19 pandemic, there have been concerns regarding potential bias in pulse oximetry measurements for people with high levels of skin pigmentation. We systematically reviewed the effects of skin pigmentation on the accuracy of oxygen saturation measurement by pulse oximetry (SpO2) compared with the gold standard SaO2 measured by CO-oximetry.MethodsWe searched Ovid MEDLINE, Ovid Embase, EBSCO CINAHL, ClinicalTrials.gov, and WHO International Clinical Trials Registry Platform (up to December 2021) for studies with SpO2–SaO2 comparisons and measuring the impact of skin pigmentation or ethnicity on pulse oximetry accuracy. We performed meta-analyses for mean bias (the primary outcome in this review) and its standard deviations (SDs) across studies included for each subgroup of skin pigmentation and ethnicity and used these pooled mean biases and SDs to calculate accuracy root-mean-square (Arms) and 95% limits of agreement. The review was registered with the Open Science Framework (https://osf.io/gm7ty).ResultsWe included 32 studies (6505 participants): 15 measured skin pigmentation and 22 referred to ethnicity. Compared with standard SaO2 measurement, pulse oximetry probably overestimates oxygen saturation in people with the high level of skin pigmentation (pooled mean bias 1.11%; 95% confidence interval 0.29 to 1.93%) and people described as Black/African American (1.52%; 0.95 to 2.09%) (moderate- and low-certainty evidence). The bias of pulse oximetry measurements for people with other levels of skin pigmentation or those from other ethnic groups is either more uncertain or suggests no overestimation. Whilst the extent of mean bias is small or negligible for all subgroups evaluated, the associated imprecision is unacceptably large (pooled SDs > 1%). When the extent of measurement bias and precision is considered jointly, pulse oximetry measurements for all the subgroups appear acceptably accurate (with Arms < 4%).ConclusionsPulse oximetry may overestimate oxygen saturation in people with high levels of skin pigmentation and people whose ethnicity is reported as Black/African American, compared with SaO2. The extent of overestimation may be small in hospital settings but unknown in community settings.Review protocol registrationhttps://osf.io/gm7ty

Label-Free but Still Constrained: Assessment of Global Proteomic Strategies for the Quantification of Hepatic Enzymes and Transporters.

Building and refining pharmacology models require "system" data derived from tissues and in vitro systems analyzed by quantitative proteomics. Label-free global proteomics offers a wide scope of analysis, allowing simultaneous quantification of thousands of proteins per sample. The data generated from such analysis offer comprehensive protein expression profiles that can address existing gaps in models. In this study, we assessed the performance of three widely used label-free proteomic methods, "high N" ion intensity approach (HiN), intensity-based absolute quantification (iBAQ) and total protein approach (TPA), in relation to the quantification of enzymes and transporters in 27 human liver microsomal samples. Global correlations between the three methods were highly significant (R2 > 0.70, P < 0.001, n = 2232 proteins). Absolute abundances of 57 pharmacokinetic targets measured by standard-based label-free methods (HiN and iBAQ) showed good agreement, whereas the TPA overestimated abundances by two- to threefold. Relative abundance distribution of enzymes was similar for the three methods, while differences were observed with TPA in the case of transporters. Variability (CV) was similar across methods, with consistent between-sample relative quantification. The back-calculated amount of protein in the samples based on each method was compared with the nominal protein amount analyzed in the proteomic workflow, revealing overall agreement with data from the HiN method with bovine serum albumin as standard. The findings herein present a critique of label-free proteomic data relevant to pharmacokinetics and evaluate the possibility of retrospective analysis of historic datasets. SIGNIFICANCE STATEMENT: This study provides useful insights for using label-free methods to generate abundance data applicable for populating pharmacokinetic models. The data demonstrated overall correlation between intensity-based label-free proteomic methods (HiN, iBAQ and TPA), whereas iBAQ and TPA overestimated the total amount of protein in the samples. The extent of overestimation can provide a means of normalization to support absolute quantification. Importantly, between-sample relative quantification was consistent (similar variability) across methods.

Empirical evaluation of kinematic soil-structure interaction effects in structures with large footprints and embedment depths

Kinematic soil-structure interaction (SSI) effects cause foundation-level motions to deviate from free-field motions. Simplified procedures to account for kinematic SSI effects are available in design guidelines for regular buildings and have been calibrated for regular buildings with limited foundation size and depth of embedment. As a result, their application to structures with much larger foundation footprints and deeper embedment depths is questionable. Kinematic interaction effects can be used to reduce foundation-level ground motions relative to those specified in the free-field, and this can be cost-effective especially for structures with larger footprints and embedment depths. The objective of this study is to quantify the extent of deviations between the use of available simplified procedures and empirical data for a select group of structures with larger footprints and embedment depths. In this study, a dataset of earthquake motions recorded at the instrumented structures in Japan is used to evaluate kinematic SSI effects, which are quantified in terms of the transfer function and the ratio of response spectra between foundation motions and corresponding free-field motions. Transfer functions represent the ratio between the free-field and the foundation level of a structure motion in the frequency domain and can be obtained by dividing Power Spectral Density functions of foundation motion and corresponding free-field motion. Finally, these empirical functions are compared to the available simplified formulations such as the semi-empirical transfer function and the ASCE/SEI 41–17 recommended ratio of response spectra, and the results are presented in terms of residuals. The overall trends of residuals indicate that the current simplified procedures tend to overestimate the foundation motions in structures with large footprints and embedment depths, and the extent of overestimation is higher for the ratio of response spectra compared to transfer functions. Thus, in future studies, these simplified procedures should be revised for applications in structures with large footprints and embedment depths.

Characterizing aircraft engine fuel and emission parameters of taxi phase for Shanghai Hongqiao International Airport with aircraft operational data

Aircraft engine emissions during landing and take-off cycle are commonly estimated on the basis of the International Civil Aviation Organization (ICAO) promulgated calculation model and emission parameters; however, the ICAO certified parameters are generally not applicable for an individual airport. In this study, the operation times, fuel and emission parameters of 8 aircraft models during taxi phase at Shanghai Hongqiao International Airport (SHA) are analyzed with the Aircraft Communication Addressing and Reporting System (ACARS) data, and compared with corresponding values referenced by the ICAO. The results show perceptible discrepancies between the SHA-specific and ICAO certified values. The taxi-out times at SHA are considerably overestimated (up to 35.3%) by ICAO for all the analyzed aircraft models, whereas the taxi-in durations are highly close to the ICAO referenced value with a variation within −6.3% to 9.7%. In the majority of cases, the localized fuel flows and emission indices (EIs) are overvalued by ICAO, and the extent of overestimation can be as large as 21.6% and 28.3%, respectively. Variabilities in operation times, fuel and emission parameters are also characterized depending on aircraft types. Additionally, as a novel attempt, the effect of engine aging on EIs is explored and no significant correlation has been detected, indicating that other factors may affect the EIs dominantly over engine age. The resulting SHA-specific emission parameters are significant towards a precise emission quantification and modeling of impacts on air quality and health.

Methane budget estimates in Finland from the CarbonTracker Europe-CH4 data assimilation system

We estimated the CH4 budget in Finland for 2004–2014 using the CTE-CH4 data assimilation system with an extended atmospheric CH4 observation network of seven sites from Finland to surrounding regions (Hyytiälä, Kjølnes, Kumpula, Pallas, Puijo, Sodankylä, and Utö). The estimated average annual total emission for Finland is 0.6 ± 0.5 Tg CH4 yr−1. Sensitivity experiments show that the posterior biospheric emission estimates for Finland are between 0.3 and 0.9 Tg CH4 yr−1, which lies between the LPX-Bern-DYPTOP (0.2 Tg CH4 yr−1) and LPJG-WHyMe (2.2 Tg CH4 yr−1) process-based model estimates. For anthropogenic emissions, we found that the EDGAR v4.2 FT2010 inventory (0.4 Tg CH4 yr−1) is likely to overestimate emissions in southernmost Finland, but the extent of overestimation and possible relocation of emissions are difficult to derive from the current observation network. The posterior emission estimates were especially reliant on prior information in central Finland. However, based on analysis of posterior atmospheric CH4, we found that the anthropogenic emission distribution based on a national inventory is more reliable than the one based on EDGAR v4.2 FT2010. The contribution of total emissions in Finland to global total emissions is only about 0.13%, and the derived total emissions in Finland showed no trend during 2004–2014. The model using optimized emissions was able to reproduce observed atmospheric CH4 at the sites in Finland and surrounding regions fairly well (correlation , bias ppb), supporting adequacy of the observations to be used in atmospheric inversion studies. In addition to global budget estimates, we found that CTE-CH4 is also applicable for regional budget estimates, where small scale (11 in this case) optimization is possible with a dense observation network.

Overestimation of Hypoglycemia in Infants with a High Hematocrit.

In neonates, hypoglycemia is an emergency condition requiring urgent treatment. Therefore, rapid and reliable blood glucose measurements are necessary. However, this step has been proven difficult because of both analytical and preanalytical variables. In our children's hospital, we incidentally observed cases of hypoglycemia that were not in line with the clinical picture of the infants. Remarkably, most of these infants had a high hematocrit. Glucose concentrations were determined in blood samples from healthy participants that were collected in Li-heparin capillary and pediatric tubes. The effect of hematocrit on glucose consumption over time was studied by artificially increasing sample hematocrits. To study the effect of sample cooling, glucose concentrations were followed over time in samples stored at room temperature and on ice. In all samples, glucose concentrations declined with time. This effect was most dramatic [up to 18 mg/dL (1 mmol/L) in the first 30 min] in samples with high hematocrits and collected in capillary tubes. Cooling of samples clearly reduced glucose consumption; however, this was not evident in the first 30 min. Overestimation of hypoglycemia in infants must be considered if samples are not centrifuged or are not analyzed immediately after sampling. The extent of overestimation is more pronounced in samples with a high hematocrit, collected in capillary tubes. Cooling of samples does not prevent glucose consumption in vitro during the first 30 min. These results emphasize that, for glucose analysis, prompt handling of samples of newborns with a high hematocrit is necessary.

Overestimation of the number of elements in a three-dimensional stimulus.

Observers' numerosity judgments in binocular stereopsis were examined in four experiments, using random-dot stereograms (RDSs) that depicted a two-dimensional (2-D) stimulus side-by-side with a three-dimensional (3-D) stimulus. When the RDSs were correctly fused, a single surface and two (or three) transparent surfaces were observed for the 2-D and 3-D stimuli, respectively. Observers completed a numerosity discrimination task, where they judged which of the two stimuli had a greater number of dot elements. Results showed that (a) the 3-D stimulus was judged to contain more elements than the 2-D stimulus, even when both had the same number of elements, (b) the amount of overestimation increased as a function of the number of elements and the binocular disparity between the front and back surfaces of the 3-D stimulus, (c) the ratio of the physical number of elements in the front surface to that in the back surface of the 3-D stimulus had no effect on the magnitude of overestimation, and (d) when the number of elements for the two surfaces were judged separately, the ratio had more effect on the judged number of elements in the back surface than in the front surface. These results indicate that the extent of overestimation in the numerosity judgment of a set of elements in a stimulus depends on the number of depth layers in which the elements are embedded.

Assessing the clinical benefit of a nomogram to predict specimen-confined disease at radical prostatectomy in patients with high-risk prostate cancer: An external validation

ObjectiveThe objective of the current study was to test generalizability and clinical value of a recently published nomogram to predict specimen-confined disease (SCD, pT2-pT3a+R0+pN0) at radical prostatectomy (RP) in patients with clinical high-risk prostate cancer (HRPCa). The nomogram allows improved decision making with curative intent within this heterogeneous patient cohort, which is important, as RP in patients with clinical HRPCa remains a topic of controversy. MethodsWe externally validated the nomogram in 1,669 men with clinical HRPCa who underwent RP and extended pelvic lymph node dissection between 1992 and 2011. A Kaplan-Meier analysis to estimate 5- and 10-year biochemical recurrence–free survival was performed. To investigate the SCD model׳s performance, the previously reported regression coefficients of the SCD nomogram were applied. Within loess calibration plots, the extent of overestimation or underestimation was graphically explored. Finally, decision curve analysis (DCA) to assess the clinical value of the SCD nomogram was performed. ResultsOverall, 49% of men showed SCD after RP. The 5- and 10-year biochemical recurrence rates for men with SCD were 66% and 56%, respectively, vs. 32% and 20%, respectively, for men without SCD (log-rank test P<0.001). External validation demonstrated comparable accuracy in relation to accuracy derived from internal validation (68.1% vs. 72.0%). Calibration was suboptimal, showing a tendency to underestimate SCD probability. In DCA, the nomogram׳s usage was associated with a clinical net benefit relative to both treating all and none. ConclusionsWithin our cohort, the nomogram׳s use was associated with a clinical net benefit according to DCA. However, one-third of men were falsely classified as having SCD or non-SCD. Nevertheless, in the absence of superior tools, the SCD nomogram represents a useful clinical decision aid.

Magnetic resonance imaging of breast cancer: factors affecting the accuracy of preoperative lesion sizing

Accurate preoperative sizing of breast cancer with imaging modalities has a great importance in the surgical planning. To assess the influence of tumor size and histology on the accuracy of measurement of cancer local extension by magnetic resonance imaging (MRI). One hundred and eighty-six patients with primary breast cancer, for a total of 221 lesions, were included in this retrospective study. Tumors were divided into five histological groups: invasive ductal carcinoma (IDC), IDC with extensive intraductal component (EIC), invasive lobular carcinoma (ILC), ductal carcinoma in situ (DCIS), and "other histology" (mucinous, papillary, medullary, tubular, and apocrine breast cancer). Microscopic measurement of the largest diameter of tumors at pathology was chosen as reference standard and compared with MRI measurement. Concordance was defined as a difference ≤ 5 mm between MRI and pathology. The mean size of tumors at pathology was 24.8 ± 19.4 mm, while at MRI it was 29.7 ± 20 mm (P < 0.05), with a significant overestimation of MRI. MRI-pathology concordance was found in 98/221 cases (44.3%), while MRI overestimated the size of 81/221 tumors (36.7%). The extent of overestimation was significantly different among the five histological groups (P < 0.05). At multivariate analysis, DCIS histology was the factor more significantly associated with MRI-pathology discordance (P = 0.0005), while the influence of tumor dimension at pathology was less significant (P = 0.0073). DCIS histology is strongly associated with discordance between MRI and pathology sizing of breast cancer. Lesion size can also influence the accuracy of MRI measurements, but to a lesser extent.

Abstract W P43: Extent of “Blooming Effect” Predicts Middle Cerebral Artery Recanalization After Intravenous Thrombolysis

Background and Purpose: Hemosiderin was shown to have a stronger T2 shortening effect than deoxyhemoglobin. Therefore, the extent of “blooming effect” of susceptibility vessel sign (SVS) might represent composition of different iron forms. We aimed to investigate the relationship between extent of overestimation of thrombus burden and middle cerebral artery (MCA) recanalization. Methods: We retrospectively examined clinical and imaging data from consecutive acute ischemic stroke patients with MCA occlusion who underwent MRI before and 24 hours after IV thrombolysis in our hospital. A delayed phase contrast enhanced T1-WI was used to measure the true size of thrombus. We then examined the association of MCA recanalization and extent of overestimation of thrombus burden. Results: We observed the presence of MCA SVS in 44 patients on initial gradient-recalled echo (GRE) scans and MCA recanalization in 21 (47.7%) patients 24 hours after treatment. The extent of overestimation of thrombus width on GRE was an acceptable predictor for MCA recanalization (odds ratio 1.584 per 10%; 95% CI: 1.090 to 2.310; p=0.016), with a receiver-operator characteristic of 0.884 (95% CI: 0.780 to 0.988; p &lt; 0.001). The optimal cut-off point for predicting recanalization was identified at 1.7814, and this yielded a sensitivity of 87.0% and a specificity of 85.7%. Conclusions: Overestimation of thrombus burden on GRE might reflect the content of hemosiderin. A larger overestimation might indicate aged thrombus, which were resistant to thrombolysis.

Does the 14C method estimate net photosynthesis? II. Implications from cyclostat studies of marine phytoplankton

Two species of marine phytoplankton, Isochrysis galbana and Chlorella kessleri, were grown in a continuous culture system on a 12-h:12-h light:dark cycle of illumination under nitrate-limited growth conditions. At growth rates of ~1d−1, production rates estimated from 14C uptake were not significantly different from production rates estimated from changes in particulate organic carbon (POC) and total organic carbon (TOC). At growth rates of ~0.35d−1, however, production rates based on uptake of 14C significantly (p<0.05) overestimated production rates based on changes in POC and TOC in all cases for C. kessleri and after 24h for I. galbana. The ratio of production based on 14C uptake to production based on changes in POC and TOC concentrations was in all cases higher after 24h than after 12h. The extent of overestimation after a 24-h incubation at ~0.35d−1 was about 23 and 40% in the cases of I. galbana and C. kessleri, respectively. Dark respiration rates estimated from changes in 14C activity during the dark period were lower than the rates estimated from changes of POC and TOC concentrations during the 12h of darkness because only about 73% of the carbon respired during the dark period had been fixed during the previous 12-h photoperiod. The fact that the 14C method tends to overestimate net carbon assimilation by a greater percentage at low growth rates than at high growth rates probably reflects the greater efficiency of intracellular recycling of respired CO2 at high growth rates. The fact that the extent of overestimation is greater when cells are grown on a light:dark cycle probably reflects the fact that not all carbon respired in the dark was fixed during the previous photoperiod and that intracellular recycling of respired CO2 during the photoperiod is inefficient during some phases of the synchronized growth that tends to be entrained by light:dark cycles.

371 ARE GENETIC VARIANTS THAT PROMOTE PSA EXPRESSION ASSOCIATED WITH MORE FAVORABLE PATHOLOGIC TUMOR FEATURES

cohort of 434 patients with a total PSA 50 ng/mL who were referred to our institution for an initial prostate biopsy. Outpatient transrectal ultrasound-guided prostate biopsies were performed according to a standardized institutional saturation scheme (18-22 cores). Logistic regression models were fitted to test the predictors of PCa at initial biopsy. Predictive accuracy estimates of biopsy outcome predictions were quantified using the area under the receiver-operating characteristic curve (AUC). Differences in AUCs were tested using the DeLong method. Regression coefficients were used to create a nomogram that was internally validated using 200 bootstrap resamples. Finally, the extent of overestimation or underestimation of the observed PCa rate at biopsy was determined with calibration plots. RESULTS: Overall, 179 (41.2%) patients were diagnosed with PCa at initial extended prostate biopsy. In accuracy analyses, PHI emerged as the most informative independent predictor of PCa (AUC: 74.5%; p 0.001). The inclusion of PHI to a multivariable logistic regression model based on established predictors of PCa (age and digital rectal examination) significantly increased the predictive accuracy of a 3.4% extent (from 75.6 to 79.0%; p 0.001). Calibration of the nomogram was good within the whole range of predicted probabilities. CONCLUSIONS: We developed a nomogram based on PHI that can assist clinicians in the decision to biopsy by giving patients an individual risk of PCa. While internal validation provided evidences of good calibration and accuracy of the tool, external validation of our findings is still required.

Do UK Higher Education Students Overestimate Their Starting Salary?*

AbstractThe wage expectations of university students have relevance for human capital theory, models of student enrolment, and public policy on the provision of higher education. However, these expectations have been the subject of relatively little research in European countries, with no contemporary evidence available in the UK. There has also been little consideration in the literature thus far of how much estimates may be biased by non‐response and sample selection. This paper thus makes an original contribution to the literature by comparing UK undergraduate students' wage expectations with the actual wages earned by the same cohort on graduation, after attempting to correct for the aforementioned statistical issues in terms of observable characteristics. In contrast to other European studies, I conclude that, on average, full‐time students overestimate their starting salary. Yet I also find substantial variation in the extent of overestimation between different subgroups.

Bioavailability of particulate metal to zebra mussels: Biodynamic modelling shows that assimilation efficiencies are site-specific

This study investigates the ability of the biodynamic model to predict the trophic bioaccumulation of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni) and zinc (Zn) in a freshwater bivalve. Zebra mussels were transplanted to three sites along the Seine River (France) and collected monthly for 11 months. Measurements of the metal body burdens in mussels were compared with the predictions from the biodynamic model. The exchangeable fraction of metal particles did not account for the bioavailability of particulate metals, since it did not capture the differences between sites. The assimilation efficiency (AE) parameter is necessary to take into account biotic factors influencing particulate metal bioavailability. The biodynamic model, applied with AEs from the literature, overestimated the measured concentrations in zebra mussels, the extent of overestimation being site-specific. Therefore, an original methodology was proposed for in situ AE measurements for each site and metal.

Hydrogen peroxide interference in chemical oxygen demand during ozone based advanced oxidation of anaerobically digested livestock wastewater

It is known that hydrogen peroxide interferes with chemical oxygen demand analysis by consuming oxidation agents such as potassium dichromate, thus leading to overestimation of the chemical oxygen demand measurements. The objective of the study was to investigate the effects of hydrogen peroxide interference and to determine true chemical oxygen demand values on interpreting treatment performance during ozone-based advanced oxidation of livestock wastewater in which hydrogen peroxide concentration and chemical oxygen demand values are dynamically changing. According to the chemical oxygen demand monitoring data, chemical oxygen demand values were always higher than the initial chemical oxygen demand load when hydrogen peroxide was involved and the treatment performance with ozone alone or ozone/ultraviolet was better than with coupled hydrogen peroxide. The extent of overestimation was proportional to the remaining hydrogen peroxide concentration and the average overestimation ratio in livestock wastewater was in the range of 0.50~0.58 mg per 1 mg of hydrogen peroxide, depending upon the quality of the wastewater treated. True chemical oxygen demand values were estimated by correlating the extent of overestimation with the remaining hydrogen peroxide concentration during treatment. The extent of overestimation decreased to zero gradually as the amount of hydrogen peroxide also approached zero as oxidation proceeded. The corrected chemical oxygen demand values indicated underlying tendency of oxidation, which could not be seen in the original chemical oxygen demand monitoring data. Application of ozone/hydrogen peroxide was more efficient for reducing chemical oxygen demand than ozone alone, as was ozone/hydrogen peroxide/ultraviolet compared to ozone/ultraviolet. When coupled with ozone, ultraviolet irradiation was more efficient than hydrogen peroxide for decreasing chemical oxygen demand during treatment of livestock wastewater.

Prostate Cancer Gene 3 (PCA3): Development and Internal Validation of a Novel Biopsy Nomogram

Urinary prostate cancer gene 3 (PCA3) represents a promising novel marker of prostate cancer detection. To test whether urinary PCA3 assay improves prostate cancer (PCa) risk assessment and to construct a decision-making aid in a multi-institutional cohort with pre-prostate biopsy data. PCA3 assay cut-off threshold analyses were followed by logistic regression models which used established predictors to assess PCa-risk at biopsy in a large multi-institutional data set of 809 men at risk of harboring PCa. Regression coefficients were used to construct four sets of nomograms. Predictive accuracy (PA) estimates of biopsy outcome predictions were quantified using the area under the curve of the receiver operator characteristic analysis in models with and without PCA3. Bootstrap resamples were used for internal validation and to reduce overfit bias. The extent of overestimation or underestimation of the observed PCa rate at biopsy was explored graphically using nonparametric loss-calibration plots. Differences in PA were tested using the Mantel-Haenszel test. Finally, nomogram-derived probability cut-offs were tested to assess the ability to identify patients with or without PCa. PCA3 was identified as a statistically independent risk factor of PCa at biopsy. Addition of a PCA3 assay improved bootstrap-corrected multivariate PA of the base model between 2% and 5%. The highest increment in PA resulted from a PCA3 assay cut-off threshold of 17, where a 5% gain in PA (from 0.68 to 0.73, p=0.04) was recorded. Nomogram probability-derived risk cut-off analyses further corroborate the superiority of the PCA3 nomogram over the base model. PCA3 fulfills the criteria for a novel marker capable of increasing PA of multivariate biopsy models. This novel PCA3-based nomogram better identifies men at risk of harboring PCa and assists in deciding whether further evaluation is necessary.

Estimation of organ and effective doses resulting from cone beam CT imaging for radiotherapy treatment planning

In this study, organ doses were measured for various kilovoltage cone beam CT exposures on the Varian Acuity simulator and an alternative method of dose estimation was also assessed. Organ doses were measured by distributing thermoluminescent dosimeters (TLDs) throughout an anthropomorphic phantom, and effective doses were calculated using International Commission on Radiological Protection (ICRP) 60 and ICRP 103 tissue-weighting factors. The ImPACT CT patient dosimetry calculator was also used to estimate doses for comparison with the TLD results. Effective doses of 15.3 mSv (19.4 mSv), 14.3 mSv (9.7 mSv) and 2.8 mSv (3.2 mSv) were calculated from the TLD measurements and ICRP 60 (ICRP 103) weighting factors for breast, pelvis and head acquisitions, respectively. When a 10 cm pencil ionisation chamber was used to measure the CT dose index, the ImPACT calculator was found to provide an adequate estimation of dose when compared with the TLD results. However, the doses for half-fan exposures were found to be overestimated, with the extent of overestimation depending on the radiosensitive organs irradiated. The organ and effective doses reported provide information for justification and optimisation of cone beam CT procedures, and are compared with doses delivered by other imaging devices. The ImPACT calculator may be used to estimate doses from cone beam CT procedures, if the potential for overestimation is acknowledged.

The Relevance of Symmetry in Line Length Perception

The length of a whole line is overestimated in comparison to the sum of its parts (Künnapas, 1955 Journal of Experimental Psychology 49 134-140). This has been considered to be true for many years, although recent studies have demonstrated that it is not always so. The perception of the length of a whole line is highly dependent on the configuration of its two parts. More precisely, whereas a whole line is perceived as longer than the sum of symmetrically bisected line parts, this overestimation decreases when compared to the sum of the lengths of asymmetrically bisected line parts. Furthermore, the extent of overestimation depends on the degree of asymmetry, so that when the two parts are greatly asymmetric in length, the whole is no longer overestimated (Wolfe et al, 2005 Perception & Psychophysics 67 967-979). Here, two experiments are reported in which a vertical/horizontal line length comparison task was used to investigate how line bisection affects length estimation. The results give rise to a new general principle characterising the mechanisms of visual perception: the sum of the lengths of two asymmetrically bisected parts is perceived as greater than that of two symmetrically bisected parts. Also bisection plays a critical role in length perception by preventing vertical bias.