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MECOM rearrangements are recurrent in myeloid neoplasms and associated with poor prognosis. However, only inv(3)(q21q26.2) and t(3;3)(q21;q26.2), the classic MECOM rearrangements resulting in RPN1-MECOM rearrangement with Mecom overexpression and GATA2 haploinsufficiency, define the distinct subtype of acute myeloid leukemia (AML) and serve as presumptive evidence for myelodysplastic syndrome based on the current World Health Organization classification. Myeloid neoplasms with non-classic 3q26.2/MECOM rearrangements have been found to be clinically aggressive, but comparative analysis of clinicopathologic and genomic features is limited. We retrospectively studied cohorts of myeloid neoplasms with classic and non-classic MECOM rearrangements. Cases with classic rearrangements consisted predominantly of AML, often with inv(3) or t(3;3) as the sole chromosome abnormality, whereas the group of non-classic rearrangements included a variety of myeloid neoplasms, often with complex karyotype without TP53 mutations and similarly dismal overall survival. Immunohistochemistry revealed Mecom protein overexpression in both groups, but overexpression in cases with non-classic rearrangements was mediated through mechanism other than GATA2 distal enhancer involvement typical for classic rearrangement. Our results demonstrated that myeloid neoplasms with non-classic 3q26.2/MECOM rearrangements encompass a diverse group of diseases with poor clinical outcome, overexpression of Mecom protein as result of non-classic mechanism of MECOM activation. This article is protected by copyright. All rights reserved.

1. Behavioural variation at the individual level has been shown to play an important role in animal ecology and evolution. Whereas most studies have focused on subadult or adult subjects, neonates have been relatively neglected, despite studies showing that neonates can exhibit consistent inter-individual differences during early developmental stages. 2. Steroid hormones, including glucocorticoids (e.g., cortisol) and androgens (e.g., testosterone), play a crucial role in foetal development and maturation and could therefore drive neonate behaviour, although this relationship is poorly understood in wild animal populations. 3. This study addresses these knowledge gaps by investigating the association between neonate fallow deer (Dama dama) fawn inter-individual variability in behavioural response to human handling and hair cortisol and testosterone levels. 4. We found strong evidence that individual neonates display repeatable differences in the way they cope with a risky situation during their first days of life, and showed how these differences are linked to cortisol and testosterone levels accumulated in utero. We showed that, when both steroids are included in the same model, neonates with high cortisol and low testosterone levels coped in a more proactive way with human handling (higher heart rate during handling, shorter latency to leave when released) compared to those with low cortisol and high testosterone levels (lower heart rate and longer latency to leave). These results provide novel insights into the proximate mechanism leading to neonate inter-individual variation in a wild population of large mammals.

Left ventricular assist devices (LVADs) have revolutionized the care of patients with advanced heart failure, yet still require concomitant medications in order to achieve the best possible clinical outcomes. Since the outset of routine placement of durable, continuous-flow LVADs, much of the medication management of these patients to date has been based on International Society of Heart and Lung Transplantation (ISHLT) guidance, most recently published in 2013. Since 2013, numerous multidisciplinary pharmacotherapy publications have increased the LVAD community's understanding of best practices with respect to medications. We identified the major domains of LVAD medication management and conducted a comprehensive search of US National Library of Medicine MEDLINE ® database using keywords chosen to identify medication-related publications of significance dated 2013 or later. Trials pertaining to the HeartMate IITM and the HeartMateTM 3 LVADs (Abbott, Chicago IL) and the HeartWareTM HVADTM System (Medtronic, Minneapolis MN) were chosen for inclusion. Highest priority for inclusion was given to prospective, randomized, controlled studies. Absent these, controlled trials (retrospective or prospective observational) were given next-highest consideration, followed by retrospective uncontrolled studies, and finally case series. Reference lists of qualified publications were reviewed to find any other publications of interest that were not discovered on initial search. Case reports were generally excluded, except where the insight gained was deemed to be uniquely pertinent. This document serves to provide a comprehensive review of the current understanding of optimal medication management in patients with durable, continuous-flow LVADs.

Congenital Central Hypoventilation Syndrome (CCHS) is a rare disease characterized by autonomic nervous system dysregulation. Central hypoventilation is the most prominent and clinically important presentation. CCHS is caused by mutations in paired-like homeobox 2b (PHOX2B) and is inherited in an autosomal dominant pattern. A co-occurrence of two asymptomatic PHOX2B variants with a classical CCHS presentation highlights the importance of clinical PHOX2B testing in parents and family members of all CCHS probands. Despite being an autosomal dominant disease, once a polyalanine repeat expansion mutation has been identified, sequencing of the other allele should also be considered.

Knowledge of the clinicopathological and molecular spectrum of pediatric renal cell carcinomas (RCC) remains limited, and approximately 16%-24% of these neoplasms cannot be classified into specific subtypes. In this review of 168 pediatric RCC prospectively registered on Children's Oncology Group AREN03B2 protocol, six RCC (3.5%) that demonstrated a unique epithelioid morphology and a peculiar immunophenotypic profile that includes expression of ALK, TFE3, and retention of INI1 was identified. Further investigation revealed ALK rearrangements in all cases, manifested molecularly by fusion transcripts of either VCL-ALK (3 patients all with sickle cell trait which had been previously reported) or TPM3-ALK (3 patients, none with sickle cell trait). Based on the shared unique morphologic, immunophenotypic, and genetic features, it was proposed that these neoplasms belonged to a distinct subgroup of RCC frequently occurring in pediatric patients, which they have termed as ALK-rearranged RCC. Importantly, additional therapeutic options may be available for these patients.

At the turn of the millennium, a neuropeptide with pronounced inhibitory actions on avian pituitary gonadotrophin secretion was identified and named gonadotrophin-inhibitory hormone (GnIH). Across bird species, GnIH acts at the level of the pituitary and the gonadotrophin-releasing hormone (GnRH) neuronal system to inhibit reproduction. Subsequent to this initial discovery, orthologues of GnIH have been identified and characterised across a broad range of species. In many vertebrates, the actions of GnIH and its orthologues serve functional roles analogous to those seen in birds. In other cases, GnIH and its orthologues exhibit more diverse actions dependent on sex, species, season and reproductive condition. The present review highlights the discovery and functional implications of GnIH across species, focusing on research domains in which the significance of this neuropeptide has been explored most.

Causal attributions are important social-cognitive predictors of forgiveness. This article presents the Transgression Attribution Questionnaire (TAQ), a measure of one's negative internal causal attributions of a specific offense. In 4 studies, scores on the TAQ showed initial evidence of estimated internal consistency, temporal stability, and construct validity. Negative internal attributions for the cause of a transgression predicted lower levels of empathy and forgiveness. Furthermore, scores on the TAQ predicted forgiveness over and above the hurtfulness of the offense, relationship commitment, and a general measure of internal causal attributions in relationships. The current research bridges research on internal causal attributions and forgiveness. Implications for the social-cognitive study of forgiveness and the measurement of causal attributions are discussed.

Purpose: For a given bowtie filter design, both the selection of material and the physical design control the energy fluence, and consequently the dose distribution, in the object. Using three previously described bowtie filter designs, the goal of this work is to demonstrate the effect that different materials have on the bowtie filter performance measures. Methods: Three bowtie filter designs that compensate for one or more aspects of the beam-modifying effects due to the differences in path length in a projection have been designed. The nature of the designs allows for their realization using a variety of materials. The designs were based on a phantom, 14 cm in diameter, composed of 40% fibroglandular and 60% adipose tissue. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis-material decomposition to produce the same spectral shape and intensity at the detector, using two different materials. With bowtie design #3, it is possible to eliminate the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. Seven different materials were chosen to represent a range of chemical compositions and densities. After calculation of construction parameters for each bowtie filter design, a bowtie filter was created using each of these materials (assuming reasonable construction parameters were obtained), resulting in a total of 26 bowtie filters modeled analytically and in the penelope Monte Carlo simulation environment. Using the analytical model of each bowtie filter, design profiles were obtained and energy fluence as a function of fan-angle was calculated. Projection images with and without each bowtie filter design were also generated using penelope and reconstructed using FBP. Parameters such as dose distribution, noise uniformity, and scatter were investigated. Results: Analytical calculations with and without each bowtie filter show that some materials for a given design produce bowtie filters that are too large for implementation in breast CT scanners or too small to accurately manufacture. Results also demonstrate the ability to manipulate the energy fluence distribution (dynamic range) by using different materials, or different combinations of materials, for a given bowtie filter design. This feature is especially advantageous when using photon counting detector technology. Monte Carlo simulation results from penelope show that all studied material choices for bowtie design #2 achieve nearly uniform dose distribution, noise uniformity index less than 5%, and nearly uniform scatter-to-primary ratio. These same features can also be obtained using certain materials with bowtie designs #1 and #3. Conclusions: With the three bowtie filter designs used in this work, the selection of material is an important design consideration. An appropriate material choice can improve image quality, dose uniformity, and dynamic range.

The human X chromosome contains ∼ 1600 genes, about 15% of which have been associated with a specific genetic condition, mainly affecting males. Blue cone monochromacy (BCM) is an X-linked condition caused by a loss-of-function of both the OPN1LW and OPN1MW opsin genes. The cone opsin gene cluster is composed of 2-9 paralogs with 99.8% sequence homology and is susceptible to deletions, duplications, and mutations. Current diagnostic tests employ polymerase chain reaction (PCR)-based technologies; however, alterations remain undetermined in 10% of patients. Furthermore, carrier testing in females is limited or unavailable. High-resolution X chromosome-targeted CGH microarray was applied to test for rearrangements in males with BCM and female carriers from three unrelated families. Pathogenic alterations were revealed in all probands, characterized by sequencing of the breakpoint junctions and quantitative real-time PCR. In two families, we identified a novel founder mutation that consisted of a complex 3-kb deletion that embraced the cis-regulatory locus control region and insertion of an additional aberrant OPN1MW gene. The application of high-resolution X-chromosome microarray in clinical diagnosis brings significant advantages in detection of small aberrations that are beyond the resolution of clinically available aCGH analysis and which can improve molecular diagnosis of the known conditions and unravel previously unrecognized X-linked diseases.

PURPOSE: To design bowtie filters with improved properties for dedicated breast CT to improve image quality and reduce dose to the patient. METHODS: The authors present three different bowtie filters designed for a cylindrical 14-cm diameter phantom with a uniform composition of 40/60 breast tissue, which vary in their design objectives and performance improvements. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis material decomposition to produce the same spectral shape and intensity at the detector, using two different materials. Bowtie design #3 eliminates the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. All three designs are obtained using analytical computational methods and linear attenuation coefficients. Thus, the designs do not take into account the effects of scatter. The authors considered this to be a reasonable approach to the filter design problem since the use of Monte Carlo methods would have been computationally intensive. The filter profiles for a cone-angle of 0° were used for the entire length of each filter because the differences between those profiles and the correct cone-beam profiles for the cone angles in our system are very small, and the constant profiles allowed construction of the filters with the facilities available to us. For evaluation of the filters, we used Monte Carlo simulation techniques and the full cone-beam geometry. Images were generated with and without each bowtie filter to analyze the effect on dose distribution, noise uniformity, and contrast-to-noise ratio (CNR) homogeneity. Line profiles through the reconstructed images generated from the simulated projection images were also used as validation for the filter designs. RESULTS: Examples of the three designs are presented. Initial verification of performance of the designs was done using analytical computations of HVL, intensity, and effective attenuation coefficient behind the phantom as a function of fan-angle with a cone-angle of 0°. The performance of the designs depends only weakly on incident spectrum and tissue composition. For all designs, the dynamic range requirement on the detector was reduced compared to the no-bowtie-filter case. Further verification of the filter designs was achieved through analysis of reconstructed images from simulations. Simulation data also showed that the use of our bowtie filters can reduce peripheral dose to the breast by 61% and provide uniform noise and CNR distributions. The bowtie filter design concepts validated in this work were then used to create a computational realization of a 3D anthropomorphic bowtie filter capable of achieving a constant effective attenuation coefficient behind the entire field-of-view of an anthropomorphic breast phantom. CONCLUSIONS: Three different bowtie filter designs that vary in performance improvements were described and evaluated using computational and simulation techniques. Results indicate that the designs are robust against variations in breast diameter, breast composition, and tube voltage, and that the use of these filters can reduce patient dose and improve image quality compared to the no-bowtie-filter case.

Behavioral findings suggest that the dorsal hippocampus (DHPC) plays a role in timing of appetitive conditioned responding. The present article explored the relationship between the extent of DHPC damage and timing ability, in a pooled analysis of three published studies from our laboratory. Initial analyses of variance confirmed our previous reports that DHPC damage reduced peak time (a measure of timing accuracy). However, the spread (a measure of timing precision) was unchanged, such that the coefficient of variation (spread/peak time) was significantly larger in DHPC-lesioned animals. This implies that, in addition to the well-established effect of DHPC lesions on timing accuracy, DHPC damage produced a deficit in precision of timing. To complement this analysis, different generalized linear mixed-effects models (GLMMs) were performed on the combined dataset, to examine which combinations of the different behavioral measures of timing were the best predictors of the degree of hippocampal damage. The results from the GLMM analysis suggested that the greater the DHPC damage, the greater the absolute difference between the observed peak time and reinforced duration. Nevertheless, this systematic relationship between damage and performance was not specific to the temporal domain: paradoxically the greater the damage the greater the magnitude of peak responding. We discuss these lesion effects in terms of scalar timing theory.

BACKGROUND Wilms tumor is the most common childhood renal tumor. Although the majority of patients with favorable histology Wilms tumor (FHWT) have good outcomes, some patients still experience disease recurrence and death from disease. The goal of the current study was to determine whether tumor-specific chromosome 1q gain is associated with event-free survival (EFS) and overall survival (OS) in patients with FHWT. METHODS Unilateral FHWT samples were obtained from patients enrolled on National Wilms Tumor Study-4 and Pediatric Oncology Group Wilms Biology Study (POG 9046). 1q gain, 1p loss, and 16q loss were determined using multiplex ligation-dependent probe amplification. RESULTS The 8-year EFS rate was 87% (95% confidence interval [95% CI], 82%-91%) for the entire cohort of 212 patients. Tumors from 58 of 212 patients (27%) displayed 1q gain. A strong relationship between 1q gain and 1p/16q loss was observed. The 8-year EFS rate was 76% (95% CI, 63%-85%) for patients with 1q gain and 93% (95% CI, 87%-96%) for those lacking 1q gain (P = .0024). The 8-year OS rate was 89% (95% CI, 78%-95%) for those with 1q gain and 98% (95% CI, 94%-99%) for those lacking 1q gain (P = .0075). Gain of 1q was not found to correlate with disease stage (P = .16). After stratification for stage of disease, 1q gain was associated with a significantly increased risk of disease recurrence (risk ratio estimate: 2.72; P = .0089). CONCLUSIONS Gain of 1q may provide a valuable prognostic marker with which to stratify therapy for patients with FHWT. A confirmatory study is necessary before this biomarker is incorporated into the risk stratification schema of future therapeutic studies. Cancer 2013;119:3887–3894. © 2013 American Cancer Society.

New methodology has been developed for the Lewis acid catalyzed synthesis of malonamides. First, the scandium(III)-catalyzed addition of diverse nucleophiles (e.g., indoles, N,N-dimethyl-m-anisidine, 2-ethylpyrrole, and 2-methylallylsilane) to coumarin-3-carboxylates has been developed to afford chromanone-3-carboxylates in high yields as a single diastereomer. Upon investigating a subsequent lanthanum(III)-catalyzed amidation reaction, a new multicomponent reaction was designed by bringing together coumarin-3-carboxylates with indoles and amines to afford indolylmalonamides, which were identified to exhibit fluorescent properties. The photophysical properties for selected compounds have been analyzed, including quantum yield, molar absorptivity, and Stokes shift. Synthetic studies of several reaction byproducts involved in the network of reaction equilibria for the three-component reaction provide mechanistic insight for the development of this methodology.

Congenital central hypoventilation syndrome (CCHS), a rare disorder characterized by alveolar hypoventilation and autonomic dysregulation, is caused by mutations in the PHOX2B gene. Most mutations occur de novo, but recent evidence suggests that up to 25% are inherited from asymptomatic parents with somatic mosaicism for these mutations. However, to date, germline mosaicism has not been reported. This report describes a family with recurrence of PHOX2B mutation-confirmed CCHS due to germline mosaicism. The first occurrence was a baby girl, noted on day 2 of life to have multiple episodes of apnea, bradycardia, and cyanosis while breathing room air. PHOX2B gene testing confirmed the diagnosis of CCHS with a heterozygous polyalanine repeat expansion mutation (PARM); genotype 20/27 (normal 20/20). Both parents tested negative for this mutation using fragment analysis (limit of detection

Infantile fibrosarcoma (IFS; also known as cellular congenital mesoblastic nephroma, CMN, when in the kidney) is a rare, undifferentiated tumour often characterized by the ETV6-NTRK3 fusion transcript. Our goal was to identify downstream pathways, diagnostic markers and potential therapeutic targets for IFS/CMN. Global gene expression, reverse-phase protein array and ETV6-NTRK3 fusion analyses were performed on 14 IFS/CMN and compared with 41 other paediatric renal tumours. These analyses confirm significant receptor tyrosine kinase (RTK) activation, with evidence of PI3-Akt, MAPK and SRC activation. In particular, GAB2 docking protein, STAT5-pTyr-694, STAT3-pSer-729 and YAP-pSer-127 were elevated, and TAZ-pSer-89 was decreased. This provides mRNA and proteomic evidence that GAB2, STAT activation and phosphorylation of the Hippo pathway transcription co-activators YAP and TAZ contribute to the RTK signal transduction in IFS/CMN. All IFS/CMN tumours displayed a distinctive gene expression pattern that may be diagnostically useful. Unexpectedly, abundant ETV6-NTRK3 transcript copies were present in only 7/14 IFS, with very low copy number in 3/14. An additional 4/14 were negative by RT-PCR and absence of ETV6-NTRK3 was confirmed by FISH for both ETV6 and NTRK3. Therefore, molecular mechanisms other than ETV6-NTRK3 fusion are responsible for the development of some IFS/CMNs and the absence of ETV6-NTRK3 fusion products should not exclude IFS/CMN as a diagnosis.

Aim: To assess continuity of medication management during transition from hospital to residential care facilities (RCFs). Method: Telephone interviews with RCF staff were performed 24 hours after patient transfer to determine the proportion of patients with: missed or significantly delayed doses; RCF medication chart not written/updated in time for the first dose; suitably packed medications not available for the first dose; and RCF medication chart written/updated by a locum doctor. Retrospective audit was used to identify discharge summary discrepancies. Results: Seventy-five doses for 37/202 (18.3%) patients were missed or significantly delayed in the 24 hours after discharge. One hundred and twenty-five (61.9%) patients did not have their medication chart written/updated and 77 (38.1%) did not have suitably packed medications available for the first dose. Locum doctors wrote RCF medication charts for 66 (32.7%) patients. One hundred and ninety-seven of 392 (50.3%) changes to regularly scheduled medications were communicated. Conclusions: Strategies are needed to address gaps in the continuity of medication management.

Background Clinical testing for PHOX2B mutations is widely used for patients with any symptoms suggestive of hypoventilation (with/without anatomic/physiologic autonomic dysregulation), though not necessarily with the congenital central hypoventilation syndrome (CCHS) phenotype. Consequently, a multitude of referrals for clinical PHOX2B testing (fragment analysis of the 20 polyalanine repeat region and/or sequencing of entire coding region) have no identifiable mutation. Whole gene deletions/duplications have recently been identified as a common disease-causing mechanism, but have not been reported in a clinical population referred for PHOX2B testing. The objective of this study was to determine if PHOX2B exon or whole gene deletion/duplication would be identified in a subset of patients referred for PHOX2B testing. The objective of this study was to determine if PHOX2B exon or whole gene deletion/duplication would be identified in a subset of patients referred for PHOX2B testing. Hypothesis: We hypothesized that PHOX2B exon or whole gene deletion or duplication would be identified in a subset of cases who were referred for genetic testing but not found to have a PHOX2B mutation with currently available clinical PHOX2B testing. Methods: Genomic DNA samples from patients that tested negative for PHOX2B mutations using fragment analysis and/or sequencing, and control samples, were screened for PHOX2B exon deletions/duplications by multiplex ligation-dependent probe amplification with confirmation by array comparative genomic hybridization. Results: Deletions of/in PHOX2B were identified in 4/250 patients and 0/261 controls. The deletions ranged from 6,216 base pairs (involving only PHOX2B exon 3) to 2.6 megabases (involving all of PHOX2B and 12 other genes). The case with PHOX2B partial exon 3 deletion had a CCHS-compatible phenotype (hypoventilation, Hirschsprung disease). Phenotypes for the other three cases, all PHOX2B whole-gene deletions, were varied including: (1) apparent life threatening event, (2) full CCHS necessitating artificial ventilation with ganglioneuroblastoma, and (3) hypoventilation during sleep. Family studies of two of the four probands showed these deletions to be maternally inherited; the mothers also had phenotypic findings of autonomic dysfunction. Conclusions: PHOX2B exon or whole gene deletion should be considered as another mechanism of disease which may include CCHS, Hirschsprung disease, and/or tumors of neural crest origin, although the genotype-phenotype relationship requires further clarification. Pediatr Pulmonol. 2012; 47: 153-161. (C) 2011 Wiley Periodicals, Inc.

Behaviors that affect the distribution of fish within aquatic systems are important considerations in the design of sampling programs. Although movements consistent with reproductive homing have been documented for muskellunge Esox masquinongy in relatively large, complex systems, quantitative data describing their distribution at the restricted spatial scale relevant to small lake fisheries are lacking. We sampled muskellunge by means of fyke netting over 2 years in each of four Wisconsin lakes with surface areas between 110 and 588 ha. Individual capture locations were recorded. Each muskellunge sampled during the first year was injected with a passive integrated transponder to allow identification of the individuals recaptured during the second year. The number of recaptures with functional transponders during the second year ranged from 15 to 43 per lake. Capture site fidelity, defined as the percentage of recaptured fish being found in the same spawning area in two consecutive years, varied ...

Business Process Management is called agile when it is able to react quickly and adequately to internal and external events. Agile Business Process Management requires putting the life cycle of business processes on a new paradigm. It is advocated in this paper that social software allows us to satisfy the key requirements for enabling agile BPM by applying the four features of social software: weak ties, social production, egalitarianism and mutual service provision. Organizational and semantic integration and responsiveness (of the business processes engineering, execution and management activities) have been identified as the main requirements for implementing an agile BPM life cycle. Social software may be used in the BPM life cycle in several manners and using numerous approaches. This paper presents seven among them and then analyzes the 'support' effects between those approaches and the underlying social software features, and the three requirements for Agile BPM. Copyright © 2011 John Wiley & Sons, Ltd.

Purpose: For the last few years, development and optimization of three-dimensional (3D) x-ray breast imaging systems, such as digital breast tomosynthesis (DBT) and computed tomography, have drawn much attention from the medical imaging community, either academia or industry. However, there is still much room for understanding how to best optimize and evaluate the devices over a large space of many different system parameters and geometries. Current evaluation methods, which work well for 2D systems, do not incorporate the depth information from the 3D imaging systems. Therefore, it is critical to develop a statistically sound evaluation method to investigate the usefulness of inclusion of depth and background-variability information into the assessment and optimization of the 3D systems. Methods: In this paper, we present a mathematical framework for a statistical assessment of planar and 3D x-ray breast imaging systems. Our method is based on statistical decision theory, in particular, making use of the ideal linear observer called the Hotelling observer. We also present a physical phantom that consists of spheres of different sizes and materials for producing an ensemble of randomly varying backgrounds to be imaged for a given patient class. Lastly, we demonstrate our evaluation method in comparing laboratory mammography and three-angle DBT systems for signal detection tasks using the phantom’s projection data. We compare the variable phantom case to that of a phantom of the same dimensions filled with water, which we call the uniform phantom, based on the performance of the Hotelling observer as a function of signal size and intensity. Results: Detectability trends calculated using the variable and uniform phantom methods are different from each other for both mammography and DBT systems. Conclusions: Our results indicate that measuring the system’s detection performance with consideration of background variability may lead to differences in system performance estimates and comparisons. For the assessment of 3D systems, to accurately determine trade offs between image quality and radiation dose, it is critical to incorporate randomness arising from the imaging chain including background variability into system performance calculations.

Colour threshold discrimination ellipses were measured for a number of states of chromatic adaptation and a range of luminance levels using the Colour Assessment and Diagnosis (CAD) test. An analysis of these results was carried out by examining the cone excitation signals along the cardinal axes that correspond to detection thresholds in the +L-M (reddish), -L+M (greenish), +S (bluish) and -S (yellowish) colour directions. The results reveal a strong linear relationship between the excitations induced by the adapting background field in each cone class and the corresponding changes needed for threshold detection. These findings suggest that the cone excitation change for threshold detection of colour signals is always the same for a given background excitation level (in any cone class), independent of the excitations generated in the other cone classes. These observations have been used to develop a model to predict colour detection thresholds for any specified background luminance and chromaticity within the range of values investigated in this study (e.g., luminances in the range 0.3 to 31 cd.m(-2) and chromaticities within the gamut of typical CRT displays). Predicted colour thresholds were found to be in close agreement with measured values with errors that do not, in general, exceed the measured within-subject variability.

Conservation of genetic resources is a challenging issue for agencies managing popular sport fishes. To address the ongoing potential for genetic risks, we developed a comprehensive set of recommendations to conserve genetic diversity of muskellunge (Esox masquinongy) in Wisconsin, and evaluated the extent to which the recommendations can be implemented. Although some details are specific to Wisconsin's muskellunge propagation program, many of the practical issues affecting implementation are applicable to other species and production systems. We developed guidelines to restrict future broodstock collection operations to lakes with natural reproduction and to develop a set of brood lakes to use on a rotational basis within regional stock boundaries, but implementation will require considering lakes with variable stocking histories. Maintaining an effective population size sufficient to minimize the risk of losing alleles requires limiting broodstock collection to large lakes. Recommendations to better app...

The modern story of CCHS began in 1970 with the first description by Mellins et al., came most visibly to the public eye with the ATS Statement in 1999, and continues with increasingly fast paced advances in genetics. Affected individuals have diffuse autonomic nervous system dysregulation (ANSD). The paired-like homeobox gene PHOX2B is the disease-defining gene for CCHS; a mutation in the PHOX2B gene is requisite to the diagnosis of CCHS. Approximately 90% of individuals with the CCHS phenotype will be heterozygous for a polyalanine repeat expansion mutation (PARM); the normal allele will have 20 alanines and the affected allele will have 24-33 alanines (genotypes 20/24-20/33). The remaining approximately 10% of individuals with CCHS will have a non-PARM (NPARM), in the PHOX2B gene; these will be missense, nonsense, or frameshift. CCHS and PHOX2B are inherited in an autosomal dominant manner with a stable mutation. Approximately 8% of parents of a CCHS proband will be mosaic for the PHOX2B mutation. A growing number of cases of CCHS are identified after the newborn period, with presentation from infancy into adulthood. An improved understanding of the molecular basis of the PHOX2B mutations and of the PHOX2B genotype/CCHS phenotype relationship will allow physicians to anticipate the clinical phenotype for each affected individual. To best convey the remarkable history of CCHS, and to describe the value of recognizing CCHS as a model for translational and transitional autonomic medicine, we present this review article in the format of a chronological story, from 1970 to the present day.

Parallel efforts by several genetic research groups have tackled common themes relating to management concerns about and recent rehabilitation opportunities for coaster brook trout Salvelinus fontinalis in Lake Superior. The questions that have been addressed include the evolutionary and genetic status of coaster brook trout, the degree of relatedness among coaster populations and their relationship to riverine tributary brook trout populations, and the role and effectiveness of stocking in maintaining and restoring coasters to Lake Superior. Congruent genetic results indicate that coasters are an ecotype (life history variant) rather than an evolutionarily significant unit or genetically distinct strain. Regional structure exists among brook trout stocks, coasters being produced from local populations. Introgression of hatchery genes into wild populations appears to vary regionally and may relate to local population size, habitat integrity, and anthropogenic pressures. Tracking the genetic diver...

Rehabilitation of migratory (“coaster”) brook trout Salvelinus fontinalis along Lake Superior's south shore is a topic of high interest among resource stakeholders and management agencies. Proposed strategies for rehabilitation of this brook trout life history variant in Wisconsin include supplemental stocking, watershed management, habitat rehabilitation, harvest regulations, or a combination thereof. In an effort to evaluate the success of coaster brook trout rehabilitation efforts, we collected genetic data from four populations of interest (Whittlesey Creek, Bois Brule River, Bark River, and Graveyard Creek) and the hatchery sources used in the Whittlesey Creek supplementation experiment. We characterized the genetic diversity of 30 individuals from each of four populations using 13 microsatellite DNA loci. Levels of genetic variation were consistent with those in similar studies conducted throughout the basin. Significant genetic variation among the populations was observed, enabling adequat...

We describe the anisotropy in imaging performance caused by oblique x-ray incidence in indirect detectors for breast tomosynthesis based on columnar scintillator screens. We use MANTIS, a freely available combined x-ray, electron, and optical Monte Carlo transport package which models the indirect detection processes in columnar screens, interaction by interaction. The code has been previously validated against published optical distributions. In this article, initial validation results are provided concerning the blur for particular designs of phosphor screens for which some details with respect to the columnar geometry are available from scanning electron microscopy. The polyenergetic x-ray spectrum utilized comes from a database of experimental data for three different anode/filter/kVp combinations: Mo/Mo at 28 kVp, Rh/Rh at 28 kVp, and W/Al at 42 kVp. The x-ray spectra were then filtered with breast tissue (3, 4, and 6 cm thickness), compression paddle, and support base, according to the oblique paths determined by the incidence angle. The composition of the breast tissue was 50%/50% adipose/glandular tissue mass ratio. Results are reported on the pulse-height statistics of the light output and on spatial blur, expressed as the response of the detector to a pencil beam with a certain incidence angle. Results suggest that themore » response is nonsymmetrical and that the resolution properties of a tomosynthesis system vary significantly with the angle of x-ray incidence. In contrast, it is found that the noise due to the variability in the number of light photons detected per primary x-ray interaction changes only a few percent. The anisotropy in the response is not less in screens with absorptive backings while the noise introduced by variations in the depth-dependent light output and optical transport is larger. The results suggest that anisotropic imaging performance across the detector area can be incorporated into reconstruction algorithms for improving the image quality of breast tomosynthesis. This study also demonstrates that the assessment of image quality of breast tomosynthesis systems requires a more complete description of the detector response beyond local, center measurements of resolution and noise that assume some degree of symmetry in the detector performance.« less

Mark–recapture studies are an important component of fisheries research and management. Underlying assumptions of such studies include minimal tag loss and negligible effects on the behavior, fitness, and survival of tagged individuals. Passive integrated transponder (PIT) tags are becoming increasingly commonplace, largely because of their small size, ease of implantation, longevity, and reportedly high rates of retention. We evaluated tag retention and survival and growth effects on age-0 muskellunge Esox masquinongy marked with PIT tags at two implantation sites, the peritoneal cavity and the dorsal musculature, during overwinter trials in Illinois and Wisconsin. For both trials, no significant differences in survival (88.0–89.8%), relative daily growth (0.0006–0.00062 mm·mm−1·d−1), or tag retention (99.5–99.8%) were observed among the two implantation groups and a control group. Survival and tag retention were also similar between trials. Our findings suggest that PIT tags implanted either in...

Competitive interactions between mature male fallow deer were investigated to determine whether antler length, body weight, age or dominance rank were related to the number of fights between individuals. Four different hypotheses were tested; the first predicted that body weight and antler length indicate individual quality and, therefore, as the difference between competitors in body weight and antler length increases, there should be a corresponding decrease in fight rate. The second and third hypotheses predicted that, as difference in dominance rank increased there would be a decrease in fight rate between males either, as a risk reduction measure or because of inhibitory control by dominant males. A fourth hypothesis predicted that, where dominance rank does not mediate fight rate, that similarity between contestants based on age might be important. If this is the case, then as the difference in age between competitors increased there should be a decrease in fight rate. Our results show that when dominance rank is controlled for, there was no relation between body weight, antler length or age with fight rate. There was a negative relation between dominance rank difference and fight rate, a result that supports both the risk reduction and inhibitory hypotheses. There was an increasing tendency to fight with closely ranked males as cohorts reached peak reproductive age; males aged 5 yr fought with other 5-yr-old males based on rank difference and males aged 6 yr fought with other males aged six and across all age groups based on rank difference. This trend was not observed in 4 or 7-yr-old males. Our results suggest that males in prime breeding condition limit potential costs of fighting (such as time and energy) by only interacting with other males of similar rank.

Supplemental stocking of walleye Sander vitreus is an important component of fishery management programs in North America. We conducted an experimental study in 23 northern Wisconsin lakes over a 4-year period to assess differences in year-class strength with and without supplemental stocking. These study lakes all hosted walleye fisheries targeting mixed-recruitment populations (i.e., ones with both natural reproduction and supplemental stocking). We tested for differences in catch per effort (CPE) between stocked and nonstocked years using a general linear mixed model. Catch per effort of age-0 walleyes was 2.3 greater per shoreline mile when lakes were stocked, suggesting that stocking increases year-class strength by about 0.13 age-0 walleyes/ acre. Catch per effort values approximated a Poisson distribution, most lakes showing low CPE of age-0 walleyes whether or not they were stocked. Stocked fingerlings were marked with oxytetracycline as fry to determine the percent contribution of stocke...

An improved understanding of the decision rules used by competing animals can be achieved by examining both the temporal structure and display rate of competitors during a contest. Current models of animal competition make different predictions regarding the behaviour of competing animals and the present study evaluates the predictions of three such models, the energetic war of attrition (eWOA), the sequential assessment game (SAG) and the cumulative assessment model (CAM) by applying them to the fighting behaviour of male fallow deer (Dama dama L.). There was no difference in rate at which the jump clash and backward push were recorded over fight duration; therefore, in terms of the temporal distribution of behavioural acts within fights, the jump clash and backward push conformed to the predictions of the SAG. There was a difference between winners and losers of fights for the frequency that the jump clash and backward push were recorded consistent with both the SAG and CAM. Analysis of bout duration showed that there was a decrease in the duration of subsequent bouts of fighting; this is only permitted under eWOA. In so far as current assessment models permit interpretation of the data, our results meet only a limited number of predictions of any one model. Given the difficulty in interpreting our data within the context of current assessment models, recommendations for the development of more complex models are presented.

Noise transfer in granular x-ray imaging phosphor screens is not proportional to the square of the magnitude of the signal transfer when the transfer properties are considered for the entire screen thickness, unless appropriately weighted at each depth of interaction. This property, known as the Lubberts effect, has not yet been studied in columnar structured screens because of a lack of a generalized description of the depth-dependent light transport. In this paper, we investigate the signal and noise transfer characteristics of columnar phosphors used in digital mammography detectors using DETECT-II, an optical Monte Carlo light transport simulation code. We first validate our choice of optical parameters for the description of granular and columnar screens using published normalized modulation transfer (MTF) experimental data. Our calculations of MTF match empirically measured MTFs for a granular film/screen analog system, and for an indirect x-ray digital imaging system with CsI:Tl screen representative of digital mammography systems. Using the depth-dependent spread functions and collection efficiencies, we calculate the signal and noise transfer functions and the Lubberts fraction, which is the ratio of the signal transfer function to the noise transfer function, for different screen thicknesses of granular and columnar phosphors. We find that the Lubbertsmore » fraction of a 85 {mu}m granular screen model corresponding to a Gd{sub 2}O{sub 2}S:Tb screen is similar to the fraction for a 100 {mu}m columnar CsI:Tl screen.« less

Purpose: The characterization of the energy dependences of tissue attenuation coefficients is fundamental in dual-energy imaging. It has been posited that a two-parameter model is both necessary and sufficient to describe these dependences for tissues of medical interest in the diagnostic energy range. In one approach the two parameters are the weighting factors for the energy-dependent linear attenuation coefficients of two distinct materials. This is commonly known as the basis material decomposition method. The purpose of this work is to describe and evaluate a method for determining these weighting factors for user-selected basis materials and tissues of interest. Methods: The method essentially says that the linear attenuation coefficient of the tissue of interest is equal, to a good approximation, to the weighted sum of the coefficients of two other distinct materials. The weights can be obtained from the resulting equation, evaluated at two different energies. Not all pairs of energies produce weights that yield accurate results. The method for finding a quasi-optimal pair of weights is described. Results: The method has been applied to a variety of combinations of tissue of interest and materials chosen to represent it. In most instances, the accuracy of the match is of the order of a few tenths of one percent over a large energy range. Even for combinations that might be expected to give poor results, water represented by PMMA and aluminum for example, the maximum deviations are of the order of one percent. Conclusion: The method produces characterizations that are at least as good as, and usually better than, the accuracy of x-ray measurements obtainable with reasonable patient doses and currently available hardware. The results also show that many different materials are reasonable choices for basis materials. The software used for this study is available on GitHub.

A central aim of the study of animal communication is to identify the mode and content of information transferred between individuals. The lateral presentation of the antler palm between male fallow deer has been described as either a signal of individual quality or an attempt to avoid fighting. In the first case two phenotypic features have been proposed by which transmission of individual quality may be facilitated. These are antler size and antler symmetry. The alternative hypothesis proposes that the lateral presentation of antlers occurs as a consequence of averting a threatening posture and may signify a reluctance to fight. We examined whether mature fallow deer use lateral palm presentation as a display during fights to indicate antler size and symmetry. We found no relationship between presentation rate of the antler and antler size and symmetry. Furthermore, males did not preferentially present their larger antler to their opponent. We also investigated whether the rate at which males presented antlers laterally during a fight was related to their ability to win the fight. Our results show that the male who performed more presentations during a fight was more likely to lose it. There were behavioural differences in the way in which a bout of presentation ended; subsequent losers tended to turn their body away from their opponent and subsequent winners tended to lower their antlers to an opponent which we interpret as an invitation to continue fighting. We conclude that the lateral palm presentation serves to de-escalate fighting between mature fallow deer. It is not a mechanism by which to communicate individual quality but rather an indication that a male is less committed to continuing investment in the current contest.

Patients with acute myeloid leukemia (AML) who relapse after hematopoietic stem cell transplantation (HCT) have dismal outcomes. Our ability to predict those at risk for relapse is limited. We examined chimerism trends post-HCT in 63 children who underwent HCT for AML or myelodysplastic syndrome (MDS). Mixed T-cell chimerism at engraftment and absence of chronic graft versus host disease (cGVHD) were associated with relapse (P = 0.04 and P = 0.02, respectively). Mixed T-cell chimerism at engraftment was predictive in patients without cGVHD (P = 0.03). Patients with engraftment mixed T-cell chimerism may warrant closer disease monitoring and consideration for early intervention.

To evaluate whether fish abundance, fish habitat, and fish–habitat associations vary across seasons in nearshore littoral zones of five northern Wisconsin lakes, we assessed fish abundances and quantified habitat characteristics in littoral zones across three seasons (spring, summer, and fall) during 1996. Seasonal responses of the fish community in the nearshore littoral zone were taxa specific and guild specific. In the nearshore littoral zone, species richness and the abundance of pumpkinseeds Lepomis gibbosus, rock bass Ambloplites rupestris, yellow perch Perca flavescens, and centrarchids differed significantly across seasons. Some habitat characteristics, including mean water depth, maximum water depth, percent floating vegetation, and percent submersed vegetation, also differed significantly among seasons. Analysis of covariance indicated that changes in fish abundance for the three species coincided with variation in habitat characteristics in the nearshore littoral zone. Significant inte...

Muskellunge Esox masquinongy are long-lived fish that typically occur at low densities. Tracking the history of individuals used as broodstock allows accurate determination of the effective population size and is essential to meeting genetic objectives for management-oriented hatchery propagation programs. We tested the utility of passive integrated transponder (PIT) tags for tracking individual muskellunge. We placed PIT tags in the cheeks of 291 adult muskellunge netted during the spring spawning season in two Wisconsin lakes. Partial fin clips were used as a secondary mark. The lakes were sampled during the following year, and 73 fish with fin clips were recovered in a sample of 271 fish. The one-year tag retention rate was 90.4% in the two lakes. Six fish without functional tags were examined for the presence of broken or malfunctioning tags, and all were missing tags. The use of PIT tags is feasible for adult muskellunge and is useful for maintaining individually based broodstock records.

To evaluate effects of habitat modification at different spatial scales, we assessed species richness and tolerance of fish assemblages in littoral zones of 17 Wisconsin lakes with extensive residential and recreational development, and compared fish associations among site-specific and lakewide conditions. Samples consisted of combined DC electrofishing and seining. Stations were randomly selected within strata defined by type of shoreline erosion control structure, including retaining walls, rock riprap, and no structure. Habitat characteristics differed among the site types. Species richness at the site level was greatest in complex habitat (riprap) regardless of fish assemblage structure. However, more effort was required to achieve complete sampling of fish species present in sites without erosion control structures. This result may be related to homogeneity of habitat among sites altered by manmade structures. We used an analysis of covariance (ANCOVA) to compare site level habitat effects ...

Computer simulation is a convenient and frequently used tool in the study of x-ray mammography, for the design of novel detector systems, the evaluation of dose deposition, x-ray technique optimization, and other applications. An important component in the simulation process is the accurate computer-generation of x-ray spectra. A computer model for the generation of x-ray spectra in the mammographic energy range from 18 kV to 40 kV has been developed. The proposed model requires no assumptions concerning the physics of x-ray production in an x-ray tube, but rather makes use of x-ray spectra recently measured experimentally in the laboratories of the Center for Devices and Radiological Health. Using x-ray spectra measured for molybdenum, rhodium, and tungsten anode x-ray tubes at 13 different kV's (18, 20, 22, ..., 42 kV), a spectral model using interpolating polynomials was developed. At each energy in the spectrum, the x-ray photon fluence was fit using 2, 3, or 4 term (depending on the energy) polynomials as a function of the applied tube voltage (kV). Using the polynomial fit coefficients determined at each 0.5 keV interval in the x-ray spectrum, accurate x-ray spectra can be generated for any arbitrary kV between 18 and 40 kV. Each anode material (Mo, Rh, W) uses a different set of polynomial coefficients. The molybdenum anode spectral model using interpolating polynomials is given the acronym MASMIP, and the rhodium and tungsten spectral models are called RASMIP and TASMIP, respectively. It is shown that the mean differences in photon fluence calculated over the energy channels and over the kV range from 20 to 40 kV were -0.073% (sigma = 1.58%) for MASMIP, -0.145% (sigma = 1.263%) for RASMIP, and 0.611% (sigma = 2.07%) for TASMIP. The polynomial coefficients for all three models are given in an Appendix. A short C subroutine which uses the polynomial coefficients and generates x-ray spectra based on the proposed model is available on the World Wide Web at http:/(/)www.aip.org/epaps/epaps.html.

The muscle and epithelial tissues of the gallbladder are regulated by a ganglionated plexus that lies within the wall of the organ. Although these ganglia are derived from the same set of precursor neural crest cells that colonize the gut, they exhibit structural, neurochemical and physiological characteristics that are distinct from the myenteric and submucous plexuses of the enteric nervous system. Structurally, the ganglionated plexus of the guinea pig gallbladder is comprised of small clusters of neurons that are located in the outer wall of the organ, between the serosa and underlying smooth muscle. The ganglia are encapsulated by a shell of fibroblasts and a basal lamina, and are devoid of collagen. Gallbladder neurons are rather simple in structure, consisting of a soma, a few short dendritic processes and one or two long axons. Results reported here indicate that all gallbladder neurons are probably cholinergic since they all express immunoreactivity for choline acetyltransferase. The majority of these neurons also express substance P, neuropeptide Y, and somatostatin, and a small remaining population of neurons express vasoactive intestinal peptide (VIP) immunoreactivity and NADPH-diaphorase enzymatic activity. We report here that NADPH-diaphorase activity, nitric oxide synthase immunoreactivity, and VIP immunoreactivity are expressed by the same neurons in the gallbladder. Physiological studies indicate that the ganglia of the gallbladder are the site of action of the following neurohumoral inputs: 1) all neurons receive nicotinic input from vagal preganglionic fibers; 2) norepinephrine released from sympathetic postganglionic fibers acts presynaptically on vagal terminals within gallbladder ganglia to decrease the release of acetylcholine from vagal terminals; 3) substance P and calcitonin gene-related peptide, which are co-expressed in sensory fibers, cause prolonged depolarizations of gallbladder neurons that resemble slow EPSPs; and 4) cholecystokinin (CCK) acts presynaptically within gallbladder ganglia to increase the release of acetylcholine from vagal terminals. Results reported here indicate that hormonal CCK can readily access gallbladder ganglia, since there is no evidence for a blood-ganglionic barrier in the gallbladder. Taken together, these results indicate that gallbladder ganglia are not simple relay stations, but rather sites of complex modulatory interactions that ultimately influence the functions of muscle and epithelial cells in the organ.

Although a goal of fisheries management is to understand factors affecting the growth rate and size structure of exploited populations, the relation between growth rates and variation in reproductive behaviors in Lepomis species has received little attention. Allocation of energy to reproductive functions (e.g., gonadal maturation, gamete production, nesting and spawning activities, and brood defense) negatively affects growth rate and, ultimately, maximum body size. To assess how social factors influence energy allocation, we manipulated population size structure of male bluegills L. macrochirus in experimental ponds and evaluated individual reproductive behavior and testes development. We predicted that smaller parental males would invest less in reproduction in the presence of larger parental males than they would in their absence. Observations were consistent with this prediction; smaller parental males had smaller testes and nested less frequently in the presence of larger males than in thei...

Although functional magnetic resonance imaging (fMRI) methods yield rich temporal and spatial data for even a single subject, universally accepted data analysis techniques have not been developed that use all the potential information from fMRI of the brain. Specifically, temporal correlations and confounds are a problem in assessing change within pixels. Spatial correlations across pixels are a problem in determining regions of activation and in correcting for multiple significance tests. We propose methods that address these issues in the analysis of task-related changes in mean signal intensity for individual subjects. Our approach to temporally based problems within pixels is to employ a model based on autoregressive-moving average (ARMAor ''Box-Jenkins'') time series methods, which we call CARMA (Contrasts and ARMA). To adjust for performing multiple significance tests across pixels, taking into account between-pixel correlations, we propose adjustment of P values with ''resampling methods.'' Our objective is to produce two- or three-dimensional brain maps that provide, at each pixel in the map, an estimated P value with absolute meaning. That is, each P value approximates the probability of having obtained by chance the observed signal effect at that pixel, given that the null hypothesis is true. Simulated and real data examples are provided.Hum. Brain Mapping 5:168-193, 1997. r 1997 Wiley-Liss, Inc.

The basis of behavioral differences between populations of river- and lake-spawning walleye Stizostedion vitreum was evaluated. We used fish from one population that migrates up a river to spawn on gravel bars and from another that remains in a lake to spawn on rocky shoals as broodstock to produce genetically tagged fry of each stock. Offspring from these broodstocks were introduced into a system containing both habitats. When the stocked walleyes had reached sexual maturation 3 and 4 years later, adults in reproductive condition were collected throughout the impoundment–river system. Walleyes that were the offspring of broodstock from the river-spawning population were captured more frequently in lotic habitat well upstream from the impoundment, whereas offspring of the lake-spawning population were found more frequently in lake habitat. This result is consistent with the hypothesis that choice of spawning habitat has a heritable component: walleyes have a genetically based response to environm...

This study investigated the dose reduction performance of several beam-hardening and K-edge filter materials for the imaging of barium or iodine during fluoroscopy. A computer model was developed to simulate the effect of added filtration on entrance exposure rate (Xp), integral dose rate (Di), contrast (C), signal to noise ratio (SNR), imaging performance per dose (SNR2/Di), and tube load. The model incorporated the response characteristics, in both manual and automatic control modes of operation, of fluoroscopic systems to increasing or decreasing x-ray intensity at the input of the image intensifier. Input parameters to the computer model included choice of filter material and thickness, a barium or iodine test object, tube potential, phantom thickness, a CsI input phosphor, and a set of algorithms for controlling the fluoroscopic system. In all cases, the performance of systems with added filtration was judged with respect to a reference system operating under comparable conditions. In general, either beam-hardening or K-edge filters provided a significant reduction in entrance exposure and integral dose rates, but with an attendant increase in tube load. For a fluoroscopic system constrained to follow a representative automatic brightness control algorithm, added filtration provided a reduction in entrance exposure and integral dose rates for all phantom or uniformly distributed barium thickness. However, the imaging performance per dose, in some cases, decreased rapidly and was less than that of the reference system at large thicknesses. Only as change in the algorithm controlling the kVcp and mA operating points on the fluoroscopic system provided an imaging performance per dose greater than the reference system's at large thicknesses. The practical implementation of adding filtration to fluoroscopic systems is most simply accomplished with beam-hardening filters rather than K-edge filters. However, the systems with K-edge added filtration can provide slightly better performance when used over a limited range of phantom thicknesses such as the range normally associated with pediatric patients.