Mate choice decisions by searchers

For more than two decades rudimentary versions of the fixed sample and sequential search strategies have provided the primary theoretical foundation for the study of mate choice decisions by searchers. The theory that surrounds these models has expanded markedly over this time period. In this paper, we review and extend results derived from these models, with a focus on the empirical analysis of searcher behavior. The basic models are impractical for empirical purposes because they rely on the assumption that searchers—and, for applied purposes, researchers—assess prospective mates based on their quality, the fitness consequences of mate choice decisions. Here we expound versions of the models that are more empirically useful, reformulated to reflect decisions based on male phenotypic characters. For some organisms, it may be possible to use preference functions to derive predictions from the reformulated models and thereby avoid difficulties associated with the measurement of male quality per se. But predictions derived from the two models are difficult to differentiate empirically, regardless of how the models are formulated. Here we develop ideas that illustrate how this goal might be accomplished. In addition, we clarify how the variability of male quality should be evaluated and we extend what is known about how this variability influences searcher behavior under each model. More general difficulties associated with the empirical study of mate choice decisions by searchers are also discussed.

Experimental characterization of a prototype detector system for carbon ion radiography and tomography

Ion beams exhibit a finite range and an inverted depth-dose profile, the Bragg peak. These favorable physical properties allow excellent tumor-dose conformality. However, they introduce sensitivity to range uncertainties. Although these uncertainties are typically taken into account in treatment planning, delivery of the intended dose to the patient has to be ensured daily to prevent underdosage of the tumor or overdosage of surrounding critical structures. Thus, imaging techniques play an increasingly important role for treatment planning and in situ monitoring in ion beam therapy. At the Heidelberg Ion Beam Therapy (HIT) center, a prototype detector system based on a stack of 61 ionization chambers has been assembled for the purpose of radiographic and tomographic imaging of transmitted energetic ions. Its applicability to ion-based transmission imaging was investigated experimentally. An extensive characterization of the set-up in terms of beam parameters and settings of the read-out electronics was performed. Overall, the findings of this work support the potential of an efficient experimental set-up as the range telescope equipped with high sensitivity and fast electronics to perform heavy ion radiography and tomography at HIT.

Processing LHC data in the UK

The Large Hadron Collider (LHC) is one of the greatest scientific endeavours to date. The construction of the collider itself and the experiments that collect data from it represent a huge investment, both financially and in terms of human effort, in our hope to understand the way the Universe works at a deeper level. Yet the volumes of data produced are so large that they cannot be analysed at any single computing centre. Instead, the experiments have all adopted distributed computing models based on the LHC Computing Grid. Without the correct functioning of this grid infrastructure the experiments would not be able to understand the data that they have collected. Within the UK, the Grid infrastructure needed by the experiments is provided by the GridPP project. We report on the operations, performance and contributions made to the experiments by the GridPP project during the years of 2010 and 2011--the first two significant years of the running of the LHC.

Characterization of glioma-cells derived from human polyomavirus-induced brain-tumors in hamsters

Intracerebral injection of human polyomavirus, JCV, into neonatal hamsters causes tumors of,glial origin. HJC is an established cell Line derived from a JCV-induced mixed hamster brain tumor with astrocytic and ependymal components. Flow cytometric and immunohistochemical analysis of HJC suggests that it is comprised of a mixed population of cells all of which contain the JCV early protein, T-antigen, in the nuclei. Five individual clonal lines, called HJC-15a to HJC-15e, were isolated by limiting dilution and were found to exhibit distinct morphological characteristics with 25-30% variation in their sizes. It was evident that each clone has unique growth rates, doubling times, and cell cycle parameters with different G(1), S, and G(2) phase times. All clonal cells showed the presence of the JCV early protein in the nucleus. Of interest was the observation from immunoprecipitation and Western analysis indicating qualitative and quantitative differences in the T-antigen isoforms produced in these cells. Similar to the parental clone, HJC-15b produced two distinct forms of JCV T-antigen isoforms, 88 kDa and 92 kDa proteins. In addition, HJC-15c was able to produce a 23-25 kDa protein which was recognized by anti-T-antigen antibody. The activity of cyclin-dependent kinases, in particular cdc2, was higher in HJC-15c than in the other cell lines. The data presented herein indicates that glioblastomas induced by viral T-antigen expression are composed of a multitude of distinct cells that possess a variety of different characteristics.

SU-E-T-308: Dosimetry of a New Minimally Invasive Episcleral Brachytherapy Device

PURPOSE

Describe the dosimetry of an episcleral brachytherapy device.

METHODS

The SMD-I device is designed to treat exudative age-related macular degeneration (AMD) and employs a Sr-90/Y-90 source encapsulated in a stainless steel cylinder. The source is welded to a flexible wire allowing it to travel from a shielded vault in the SMD-I handle to the distal end of a curved cannula to deliver a therapeutic dose of radiation through the sclera to the neovascular target in the subchoroidal space. The SMD-I handle and vault are comprised of Ultem, a lightweight radiation tolerant plastic, which shields the surgeon. Dose calculations were performed using the MCNPX radiation transport code. The absolute dose rate was determined using radiochromic film (GAFChromatic© MD-55) at a point in solid water 2.0mm from the source center perpendicular to the cannula. Dose rates at several depths were measured using Kodak EDR2 film in water equivalent phantoms to compare with the absolute dose rate measurement and MCNPX calculations. The surgeon's hand dose received while manipulating the device with the source in the vault was measured using standard TL (thermoluminescence) finger ring dosimeters, TL ChipstratesTM, and calculated with MCNPX.

RESULTS

The absolute dose rate 2.0mm from the source center is 0.45 Gy/min/mCi. The EDR2 film results agree with the absolute dose measurement and the MCNPX calculations. The dose rate decreases rapidly with depth so that the dose at the target depth (3mm) is approximately 8 times less than at 1mm depth (sclera). The dose distribution is sensitive to the angle between the cannula and the neovascular plane. Both TL methods yield a maximum dose rate of 6 μSv/min mCi to the surgeon's fingers consistent with the MCNPX calculation.

CONCLUSIONS

The SMD-I device permits accurate delivery of a therapeutic radiation dose for the treatment of exudative AMD. Russell J. Hamilton is a founder and currently serves on the Scientific Advisory Board of Salutaris Medical Devices, Inc. Wendell Lutz and Thomas Cetas serve on the Scientific Advisory Board of Salutaris Medical Devices, Inc. All authors have received financial support from Salutaris Medical Devices, Inc.

SU-E-J-59: Dual Imaging Guided Localization System for Spine Radiosurgery

PURPOSE

To compare localization accuracies between an ExacTrac and cone beam computed tomography (CBCT) systems for single fraction spine adiosurgery. The work also aimed to evaluate the inherent systematic deviation of both ExacTrac and CBCT systems to achieve highly accurate localization in the spine radiosurgery.

METHODS

ExacTrac and CBCT imaging systems were evaluated using the linac isocenter as the mutual reference point. First, a BB was placed in an anthropomorphic pelvic phantom. The phantom was localized with both imaging systems and the procedure was repeated 12 times. These results were used to devise a localization protocol using both imaging systems in spine radiosurgery, and employed for 51 patients (81 isocenters) prescribed for single fraction treatment. The displacement discrepancy between the isocenter and two systems were quantified in four dimensions (three translations, one rotation). A Student's two-tailed t-test was used to test for significant differences between the two imaging systems.

RESULTS

The phantom study showed 1.4±0.5, 0.6±0.5, and 0.1±0.5 mm differences between the two imaging systems in the anterior/posterior (A/P), superior/inferior (S/I) and left/right (L/R) directions, respectively. The angular difference was minimal along all three axes. The patient study revealed similar isocenter discrepancies between ExacTrac and CBCT of 1.1 ± 0.7 mm, 1.0±0.9 mm, and 0.2±0.9 mm in the A/P, S/I, and L/R directions, respectively, with the A/P and S/I directions showing statistical significance ((t(80) = 13.5 and 7.6 respectively, p = 0.000). The couch yaw discrepancy was 0 ± 0.3°. Overall, 1 mm systematic differences were observed in the A/P and S/I directions between ExacTrac and CBCT localization systems, both in phantom and patient. A procedure was developed to mitigate this systematic discrepancy.

CONCLUSIONS

These findings have justified our patient localization tolerance levels of 2 mm translation and 1 degree rotation for spine SRS treatment.

Lightening the load? A systematic review of community pharmacy-based weight management interventions

The extent to which community pharmacies can increase capacity for weight management is unknown. Thus, the objective of the present paper was to evaluate the effectiveness and cost-effectiveness of community pharmacy weight management interventions. This paper used a design of systematic review and narrative synthesis. Electronic databases (1999-2009) were searched, including Medline, EMBASE, CINAHL and Pharm-line. Weight management studies in community pharmacies were eligible for the inclusion criteria. All languages and study designs were considered. Outcome measures included body weight or anthropometry (at baseline and at least one follow-up time point). Data were extracted through independent, duplicate data extraction and quality assessment. As a result, 10 studies were included, totalling 2,583 service users and 582 pharmacies from the USA, the UK, Switzerland, Spain and Denmark. One was a randomized controlled trial of a meal-replacement versus a reduced calorie diet. A non-randomized controlled before and after study compared community pharmacist treatment using Orlistat with usual care. Eight studies were uncontrolled. Five studies described behaviour change techniques. Long-term (12 months) mean weight loss measured in three studies ranged from 1.1 to 4.1 kg. Four uncontrolled studies reported statistically significant weight loss. No study reported economic evaluations. Currently, there is insufficient evidence for the effectiveness and cost-effectiveness of community pharmacy-based weight management initiatives to support investment in their provision.

Apolipoprotein E-e4, processing speed, and white matter volume in a genetically enriched sample of midlife adults

Healthy midlife children of a parent with Alzheimer's disease ([AD] N = 23; 9 male) participated in neuropsychological testing, and magnetic resonance imaging (MRI) of brain volumetrics were obtained. In all, 35% of the sample were apolipoprotein E (ApoE)-e4 positive (n = 8; 5 male). The ApoE-e4 group exhibited significantly slower performances on an executive function and processing speed measure and had less white matter volume than the non-ApoE-e4 group. Lesser white matter volume was significantly correlated with slower processing speed. Processing speed and changes in white matter volume might be indicators of preclinical decline in AD.

Lack of listing status awareness: results of a single-center survey of hemodialysis patients

This study surveyed hemodialysis patients in an urban transplant center serving a predominantly African American population to identify existing and potential barriers to transplantation. The survey used the Dialysis Patient Transplant Questionnaire (DPTQ) to collect self-reported data including interest in a deceased donor kidney transplant and self-reported listing status. We compared patients' survey data to their UNOS listing and computerized medical record at time of interview. Among the 116 patients surveyed, 83 (71.6%) reported interest in a deceased donor kidney transplant. Eighteen (52.9%) of the 34 patients undergoing pretransplantation workup were unaware of their true listing status, and 88.9% of these patients mistakenly believed they were wait listed. All of the patients who mistakenly thought they were listed were undergoing workup. Finding that a significant number of hemodialysis patients who want a deceased donor kidney transplant mistakenly think they are listed when they are not is a documentable deficiency in communication and a potential barrier to transplantation. The finding highlights a correctable problem in communication and work flow that could help to improve transplant center effectiveness. It also reveals that self-reported waiting list status significantly overestimated true waiting list status for our patients at time of interview.

Quantifying rater drift on the HAM-D in a sample of standardized rater training events: Implications for reliability and sample size calculations

Introduction/objectives/aims

Though rater drift in clinical trials has long been understood to negatively impact trial results, few studies have systematically quantified this. We examined training data for the HAM-D (Hamilton Depression Scale, 17-item version) at two time points to measure the impact.

Methods

Raters participating in a standardized training scored the HAM-D based on two videotaped interviews of depressed patients. To assess drift, data from an initial, post-online training session was compared to data obtained 12 months later. Intra-class correlation coefficients (Shrout & Fliess, 1979) and concordance with expert ratings were compared.

Results

Intra-class correlation coefficients (ICC) for raters (n = 167) following initial training were good to excellent for individual raters (.695–.976, p < .0001) and good for the overall cohort (.752, p < .0001). Concordance with expert ratings was excellent at 99.3%. The overall ICC fell to .730 at the second assessment and although the upper bound of individual performance remained in the good to excellent range, the frequency of scores in the poor to fair range (< .65) increased. Concordance also fell slightly to 87%.

Conclusions

Rater drift occurred over 12 months, as gauged by the metrics of reliability and concordance. Drift was apparent in a limited portion of the cohort but resulted in a lower overall ICC at the second time point. Because studies are generally powered assuming that the ICC remains stable, there are implications for both this power calculation and the required sample size.

Observer agreement regarding the necessity of retreatment of previously coiled recurrent cerebral aneurysms

BACKGROUND AND PURPOSE

The decision regarding whether or not to retreat a previously treated aneurysm not only directly impacts patient care but also serves as a primary outcome measure in numerous, leading randomized controlled trials of modified coils. Our aim was to determine the degree of interobserver variability regarding the need and type of treatment for recurrent aneurysms following coil embolization.

MATERIALS AND METHODS

Twenty-seven previously treated recurrent aneurysms were identified. Five independent readers rated each aneurysm on a 5-point scale: 1, definitely do not retreat; 2, probably do not retreat; 3, unsure; 4, probably retreat; and 5, definitely retreat. The readers noted, in grades 2-5, the type of retreatment preferred, including simple coiling, balloon- or stent-assist coiling, or surgical clipping. Intraobserver agreement κ was calculated. Retreatment recommendations were evaluated between observers by using a Wilcoxon signed rank comparison. Descriptive statistics were performed for categoric treatment-type comparisons.

RESULTS

At least 2- or 3-point differences between 2 readers were present in 17 (63%) and 11 (41%) of 27 cases, respectively. The median κ was 0.27 (range, 0.04-0.43), which indicates fair agreement. Differences between readers varied, with readers 4 and 5 more often recommending retreatment compared with reviewers 1-3 (P < .05). Wide variation was noted in treatment approach, with recommendations for surgical clipping ranging from 2 (7%) to 18 (67%) of 27 cases between readers 1 and 5.

CONCLUSIONS

The current study demonstrates substantial variability among observers not only in whether to retreat a recurrent aneurysm but also how to treat it. These findings suggest that patient management varies widely across treating physicians and also calls into question the use of "retreatment" as an objective end point in clinical trials.

A comparison of intermediate and long-acting insulins in people with type 2 diabetes starting insulin: an observational database study

AIMS

Insulin is normally added to oral glucose-lowering drugs in people with type 2 diabetes when glycaemic control becomes suboptimal. We evaluated outcomes in people starting insulin therapy with neutral protamine Hagedorn (NPH), detemir, glargine or premixed insulins.

METHODS

Insulin-naïve people with type 2 diabetes (n = 8009), ≥ 35 years old, HbA(1c) ≥ 6.5% and begun on NPH (n = 1463), detemir (n = 357), glargine (n = 2197) or premix (n = 3992), were identified from a UK database of primary care records (The Health Improvement Network). Unadjusted and multivariate-adjusted analyses were conducted, with persistence of insulin therapy assessed by survival analysis.

RESULTS

In the study population (n = 4337), baseline HbA(1c) was 9.5 ± 1.6%, falling to 8.4 ± 1.5% over 12 months (change -1.1 ± 1.8%, p < 0.001). Compared with NPH, people taking detemir, glargine and premix had an adjusted reduction in HbA(1c) from baseline, of 0.00% (p = 0.99), 0.19% (p < 0.001) and 0.03% (p = 0.51). Body weight increased by 2.8 kg overall (p < 0.001), and by 2.3, 1.7, 1.9, and 3.3 kg on NPH, detemir, glargine and premix (p < 0.001 for all groups); insulin dose at 12 months was 0.70 (overall), 0.64, 0.61, 0.56 and 0.76 U/kg/day. After 36 months, 57% of people on NPH, 67% on glargine and 83% on premix remained on their initially prescribed insulin.

DISCUSSION AND CONCLUSION

In routine clinical practice, people with type 2 diabetes commenced on NPH experienced a modest disadvantage in glycaemic control after 12 months compared with other insulins. When comparing the insulins, glargine achieved best HbA(1c) reduction, while premix showed greatest weight gain and the highest dose requirement, but had the best persistence of therapy.