bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dependence of Photochemical Reactivity of the All‐trans Retinal Protonated Schiff Base on the Solvent and the Excitation Wavelength
Authors: Zgrablić Goran , Ricci Maria , Novello Anna Maria , Parmigiani Fulvio 
Published: January 2010

AbstractAn all‐optical experimental technique aimed at measuring photoisomerization quantum yield (ϕ) of the all‐trans protonated Schiff base of retinal in solution has been implemented. Upon the increase in the excitation wavelength from 400 to 540 nm a slight increase in ϕ from 0.16 ± 0.03 to 0.20 ± 0.02 is observed in the chromophore dissolved in methanol, whereas the ϕ value of the one dissolved in acetonitrile varies only from 0.22 ± 0.03 (400 nm) to 0.23 ± 0.04 (540 nm). The results suggest that dissipation of the excited‐state vibrational energy excess, along with environment‐induced modifications of the potential energy surfaces are necessary for an efficient retinal photoisomerization in both solvent and protein environment.
ORIGINAL ARTICLE: RET‐Y and RBC‐Y in the diagnosis of iron deficiency associated with anaemia of inflammation
Authors: JAYARANEE S. , STHANESHWAR P. 
Published: January 2010

SummaryWe evaluated the usefulness of RET‐Y and RBC‐Y in distinguishing functional iron deficiency from iron‐deficiency anaemia (IDA) in patients with anaemia of inflammation (AI). Sixty healthy blood donors constituted the control group. We studied RET‐Y and RBC‐Y in 115 patients with hypochromic/microcytic anaemia. Of these 42 patients had uncomplicated IDA and 73 had AI. The AI patients were further subdivided into AI with IDA and AI with functional IDA based on soluble transferrin receptor (sTfR) levels. The mean RBC‐Y and RET‐Y values in iron‐deficient patients were 122.4 and 119.8, respectively, which were significantly lower than the control (P < 0.001). The mean level of RET‐Y in patients with AI associated with IDA was 149.3 and this level in AI patients with functional iron deficiency was 147.4. RET‐Y levels in both subgroups of AI patients were significantly lower than control but no significant difference was observed between the two subgroups. Similar findings were observed for RBC‐Y. Receiver operating characteristic analysis also showed lower specificity for RBC‐Y and RET‐Y compared with that of sTfR and its log ferritin ratio (F‐index). RET‐Y and RBC‐Y are useful in the diagnosis of simple IDA but have limited utility in the diagnosis of IDA with AI.
ORIGINAL ARTICLE: Genetics, adaptation, and invasion in harsh environments
Authors: Gomulkiewicz Richard , Holt Robert D. , Barfield Michael , Nuismer Scott L. 
Published: January 2010

AbstractWe analyze mathematical models to examine how the genetic basis of fitness affects the persistence of a population suddenly encountering a harsh environment where it would go extinct without evolution. The results are relevant for novel introductions and for an established population whose existence is threatened by a sudden change in the environment. The models span a range of genetic assumptions, including identical loci that contribute to absolute fitness, a two‐locus quantitative genetic model with nonidentical loci, and a model with major and minor genes affecting a quantitative trait. We find as a general (though not universal) pattern that prospects for persistence narrow as more loci contribute to fitness, in effect because selection per locus is increasingly weakened with more loci, which can even overwhelm any initial enhancement of fitness that adding loci might provide. When loci contribute unequally to fitness, genes of small effect can significantly reduce extinction risk. Indeed, major and minor genes can interact synergistically to reduce the time needed to evolve growth. Such interactions can also increase vulnerability to extinction, depending not just on how genes interact but also on the initial genetic structure of the introduced, or newly invaded, population.
SYNTHESIS: The role of adaptive trans‐generational plasticity in biological invasions of plants
Authors: Dyer Andrew R. , Brown Cynthia S. , Espeland Erin K. , McKay John K. , Meimberg Harald , Rice Kevin J. 
Published: January 2010

AbstractHigh‐impact biological invasions often involve establishment and spread in disturbed, high‐resource patches followed by establishment and spread in biotically or abiotically stressful areas. Evolutionary change may be required for the second phase of invasion (establishment and spread in stressful areas) to occur. When species have low genetic diversity and short selection history, within‐generation phenotypic plasticity is often cited as the mechanism through which spread across multiple habitat types can occur. We show that trans‐generational plasticity (TGP) can result in pre‐adapted progeny that exhibit traits associated with increased fitness both in high‐resource patches and in stressful conditions. In the invasive sedge,Cyperus esculentus, maternal plants growing in nutrient‐poor patches can place disproportional number of propagules into nutrient‐rich patches. Using the invasive annual grass,Aegilops triuncialis, we show that maternal response to soil conditions can confer greater stress tolerance in seedlings in the form of greater photosynthetic efficiency. We also show TGP for a phenological shift in a low resource environment that results in greater stress tolerance in progeny. These lines of evidence suggest that the maternal environment can have profound effects on offspring success and that TGP may play a significant role in some plant invasions.
Overcoming Global and Regional Collective Action Impediments
Authors: Sandler Todd 
Published: January 2010

AbstractAt the outset, the article traces the increased prevalence of transnational collective action to globalization, technological progress, population growth and enhanced surveillance. The article then identifies 15 factors that facilitate successful collective action at the global and regional level. Generally, collective action problems with more of these facilitators are easier to address and, in some instances, will require no explicit policy intervention. By identifying essential facilitators and inhibitors, the article indicates where collective action has either a good or bad prognosis. Thus, scarce policy resources can be directed toward those issues where the prognosis is unfavorable. Much of the article concentrates on spatial considerations, institutional engineering and aggregator technologies. For regional collective action concerns, spatial considerations are particularly important since propinquity and relative location of countries influence how actions of other countries affect social well‐being. Simple institutional designs – cost sharing, thresholds and refunds – can effectively overcome impediments to collective action by making contributors view their net benefits from the viewpoint of the collective. Throughout the article, contrasts are drawn between global and regional collective action. Myriad examples and policy recommendations are offered.Policy Implications Global collective action can differ fundamentally from regional collective action. These differences must inform policy making in addressing collective action impediments. Spatial considerations can play an important role in the underlying incentives motivating regional collective action.Scarce policy‐making resources should be directed at those collective action problems that face the greatest impediments and/or the fewest facilitators – e.g. global warming.The manner in which individual contributions add to the overall amount of the collective action is an essential consideration when designing policies.Simple institutional designs – cost sharing and refunds – can effectively overcome impediments to collective action by aligning countries’ incentives.
Nuclear Disarmament and the 2010 NPT Review Conference
Authors: Clarke Michael 
Published: January 2010

AbstractThe upcoming 2010 NPT RevCon, unlike its predecessor in 25, appears set to take place in an international climate characterised by a widespread hope that there will be practical movement toward nuclear disarmament. This hope has been expressed not only by long‐term arms control and disarmament advocates but also by such US ‘cold warriors’ as former Secretary of State Henry Kissinger. Thus, this survey article will address two key questions: (1) why is progress on nuclear disarmament seen by many as vital for reinvigorating the international non‐proliferation regime? (2) What are the prospects for progress on nuclear disarmament at the 2010 NPT RevCon?
Museum as Soup Kitchen
Authors: Gurian Elaine Heumann 
Published: January 2010

AbstractIn this paper, I suggest that museums have not explored their potential opportunities enough when dealing with their communities under stressful conditions. Each reader, however, should decide when what I am talking about is no longer appropriate for museums in general or your museum in particular. While some museums have moved more in the direction of serving their communities, I am struck by how little philosophical change has actually taken place in most museums after a year into this universal economic downturn. I argue that incorporating a broader palette of social services may make institutions more useful, but at some point these institutions might cease to be traditional museums. My question would be: “Should you care?” I do not suggest that all museums become full‐service community centers, though some might explore that option. Perhaps the question might become: How do we expand our services so that we make museums’ important physical assets of safe civic space and objects useful for tangible three‐dimensional learning into more relevant programs that reach all levels of community, and are rated by many more as essential to their needs and their aspirations for their children?
From Knowing to Not Knowing: Moving Beyond “Outcomes”
Authors: Pekarik Andrew J. 
Published: January 2010

AbstractThe ways that museums measure the success of their exhibitions reveal their attitudes and values. Are they striving to control visitors so that people will experience what the museum wants? Or are they working to support visitors, who seek to find their own path? The type of approach known as “outcome‐based evaluation” weighs in on the side of control. These outcomes are sometimes codified and limited to some half‐dozen or so “learning objectives” or “impact categories.” In essence, those who follow this approach are committed to creating exhibitions that will tell visitors what they must experience. Yet people come to museums to construct something new and personally meaningful (and perhaps unexpected or unpredictable) for themselves. They come for their own reasons, see the world through their own frameworks, and may resist (and even resent) attempts to shape their experience. How can museums design and evaluate exhibitions that seek to support visitors rather than control them? How can museum professionals cultivate “not knowing” as a motivation for improving what they do?
The use of PET images for radiotherapy treatment planning: An error analysis using radiobiological endpoints
Authors: Perrin R. , Evans P. M. , Webb S. , Partridge M. 
Published: January 2010

Purpose:There is significant current interest in the use of biological image guidance in radiotherapy planning. In lung‐cancer treatment, tumor motion due to respiration is known to be a limitation. This is particularly true in PET, where image data are collected over a number of minutes. An in‐house‐developed 4D PET acquisition mode is described and an analysis of the effects of acquisition parameters on the reconstructed image quality is presented. The potential impact of the resulting biological image quality on radiotherapy planning is then quantified in terms of tumor control probability (TCP).Methods:Data were acquired using a human torso phantom comprised of a hot‐filled spheroidal “tumor” ( in diameter) suspended in an air‐filled “lung” cylinder and surrounded by a warm ‐filled background. Two different sphere‐to‐background (S/B) ratios were used. The tumor was connected to a 3‐axis computer‐controlled motion stage and could be moved during PET data acquisition. Images were acquired with a range of count statistics, motion blurring, and CT attenuation correction (CTAC) misalignment. Four simple models were proposed for the assignment of clonogenic cell density according to the voxel value. The impact of image artifacts was then assessed by calculating the TCP, which is the probability that no clonogenic tumor cell remains after a given dose of radiation. TCP was calculated for a uniform dose distribution in the tumor.Results:Reduced count statistics and misaligned CTAC images had the most detrimental impact on the image fidelity. It was found that in both cases the images became less intense, demonstrated by smaller number of voxels at the maximum values. The maximum TCP difference between images with the least and most noise was 3.4%, and with weakest and strongest CT misalignment artifacts, it was 3.2% . Motion blurring only contributed weakly to the TCP imprecision at 1.7% between best‐ and worst‐case images. However, the model‐calculated TCP showed increasing differences from the ground truth as the complexity of the model increased [maximum difference of (model 3)], which could be attributed to the partial volume effect.Conclusions:Based on the results of this study, it is believed that simple techniques of biologically guided radiotherapy planning for lung cancer should be feasible at intermediate contrast levels (tumor‐to‐background ratio of) with the clinically achievable image quality.
Impact of anatomical interventions on the localization of post‐prostatectomy cancer patients
Authors: Diot Quentin , Olsen Christine , Kavanagh Brian , Raben David , Miften Moyed 
Published: January 2010

Purpose:Anatomical deformations of prostate‐bed, rectum, and bladder can compromise the targeting accuracy in post‐prostatectomy cancer patients. In this work, the impact of anatomical interventions on the localization data from post‐prostatectomy patients who received image‐guided IMRT was analyzed.Methods:Patients were localized daily with online kilovoltage cone‐beam computed tomography (kV‐CBCT). The target and the organs at risk (OARs) positional and volumetric changes were evaluated and couch shifts were applied. For patients with large target or OAR volumetric changes, quantified by either a rectal or bladder wall displacement of on the CBCT sagittal images compared to the planning CT, repeated localization CBCT scans were performed following an interventional procedure. The procedure involves insertion of a catheter to deflate the rectum, evacuation of stools, and/or adjustment of bladder filling. The required shifts were then evaluated, and the IMRT treatment was subsequently delivered after proper patient positioning. The pre‐ and post‐intervention shifts were compared in the lateral [left‐right (LR)], longitudinal [superior‐inferior (SI)], and vertical [anterior‐posterior (AP)] directions. The percentage of shifts larger than 5 mm in all directions was also compared. Clinical target volume to planning target volume (CTV‐to‐PTV) expansion margins were estimated based on the pre‐ and post‐intervention localization data.Results:Intervention was performed on all patients treated between October 2008 and March 2009. The number of interventions ranged from 2 to 12 with a median number of 5, resulting in a total of 96 pairs of pre‐ and post‐intervention shifts. The mean value and standard deviation of the shifts from pre‐ versus post‐intervention data were LR, vs ; SI, vs ; and AP, vs . The mean 3D shift distance was vs . The percentage of pre‐intervention shifts larger than 5 mm were 7%, 7%, and 45% in the LR, SI, and AP directions, respectively, compared to 8%, 4%, and 21% for post‐intervention. Localization data from pre‐ and post‐intervention procedures suggest that treatments that do not include intervention to correct for rectum/bladder anatomical variations require an additional 3.3 mm CTV‐to‐PTV margin.Conclusions:Anatomical interventions reduced the localization errors arising from large volume and shape changes in the rectum and/or bladder compared to treatments without interventions.
Dosimetric validation of a commercial Monte Carlo based IMRT planning system
Authors: Grofsmid Dennis , Dirkx Maarten , Marijnissen Hans , Woudstra Evert , Heijmen Ben 
Published: January 2010

Purpose:Recently a commercial Monte Carlo based IMRT planning system (Monaco version 1.0.0) was released. In this study the dosimetric accuracy of this new planning system was validated.Methods:Absolute dose profiles, depth dose curves, and output factors calculated by Monaco were compared with measurements in a water phantom. Different static on‐axis and off‐axis fields were tested at various source‐skin distances for 6, 10, and 18 MV photon beams. Four clinical IMRT plans were evaluated in a water phantom using a linear diode detector array and another six IMRT plans for different tumor sites in solid water using a 2D detector array. In order to evaluate the accuracy of the dose engine near tissue inhomogeneities absolute dose distributions were measured with Gafchromic EBT film in an inhomogeneous slab phantom. For an end‐to‐end test a four‐field IMRT plan was applied to an anthropomorphic lung phantom with a simulated tumor peripherally located in the right lung. Gafchromic EBT film, placed in and around the tumor area, was used to evaluate the dose distribution.Results:Generally, the measured and the calculated dose distributions agreed within 2% dose difference or 2 mm distance‐to‐agreement. But mainly at interfaces with bone, some larger dose differences could be observed.Conclusions:Based on the results of this study, the authors concluded that the dosimetric accuracy of Monaco is adequate for clinical introduction.
Accurate MTF measurement in digital radiography using noise response
Authors: Kuhls‐Gilcrist Andrew , Jain Amit , Bednarek Daniel R. , Hoffmann Kenneth R. , Rudin Stephen 
Published: January 2010

Purpose:The authors describe a new technique to determine the system presampled modulation transfer function (MTF) in digital radiography using only the detector noise response.Methods:A cascaded‐linear systems analysis was used to develop an exact relationship between the two‐dimensional noise power spectrum (NPS) and the presampled MTF for a generalized detector system. This relationship was then utilized to determine the two‐dimensional presampled MTF. For simplicity, aliasing of the correlated noise component of the NPS was assumed to be negligible. Accuracy of this method was investigated using simulated images from a simple detector model in which the “true” MTF was known exactly. Measurements were also performed on three detector technologies (an x‐ray image intensifier, an indirect flat panel detector, and a solid state x‐ray image intensifier), and the results were compared using the standard edge‐response method. Flat‐field and edge images were acquired and analyzed according to guidelines set forth by the International Electrotechnical Commission, using the RQA 5 spectrum.Results:The presampled MTF determined using the noise‐response method for the simulated detector system was in close agreement with the true MTF with an averaged percent difference of 0.3% and a maximum difference of 1.1% observed at the Nyquist frequency. The edge‐response method of the simulated detector system also showed very good agreement at lower spatial frequencies (less than ) with an averaged percent difference of 1.6% but showed significant discrepancies at higher spatial frequencies (greater than ) with an averaged percent difference of 17%. Discrepancies were in part a result of noise in the edge image and phasing errors. For all three detector systems, the MTFs obtained using the two methods were found to be in good agreement at spatial frequencies less than with an averaged percent difference of 3.4%. Above , differences increased to an average of 20%. Deviations of the experimental results largely followed the trend seen in the simulation results, suggesting that differences between the two methods could be explained as resulting from the inherent inaccuracies of the edge‐response measurement technique used in this study. Aliasing of the correlated noise component was shown to have a minimal effect on the measured MTF for the three detectors studied. Systems with significant aliasing of the correlated noise component (e.g., based detectors) would likely require a more sophisticated fitting scheme to provide accurate results.Conclusions:Results indicate that the noise‐response method, a simple technique, can be used to accurately measure the MTF of digital x‐ray detectors, while alleviating the problems and inaccuracies associated with use of precision test objects, such as a slit or an edge.
Near optimal energy selective x‐ray imaging system performance with simple detectors
Authors: Alvarez Robert E. 
Published: January 2010

Purpose:This article describes a method to achieve near optimal performance with low energy resolution detectors. Tapiovaara and Wagner [Phys. Med. Biol. 30, 519–529 (1985)] showed that an energy selective x‐ray system using a broad spectrum source can produce images with a larger signal to noise ratio (SNR) than conventional systems using energy integrating or photon counting detectors. They showed that there is an upper limit to the SNR and that it can be achieved by measuring full spectrum information and then using an optimal energy dependent weighting.Methods:A performance measure is derived by applying statistical detection theory to an abstract vector space of the line integrals of the basis set coefficients of the two function approximation to the x‐ray attenuation coefficient. The approach produces optimal results that utilize all the available energy dependent data. The method can be used with any energy selective detector and is applied not only to detectors using pulse height analysis (PHA) but also to a detector that simultaneously measures the total photon number and integrated energy, as discussed by Roessl et al. [Med. Phys. 34, 959–966 (2007)]. A generalization of this detector that improves the performance is introduced. A method is described to compute images with the optimal SNR using projections in a “whitened” vector space transformed so the noise is uncorrelated and has unit variance in both coordinates. Material canceled images with optimal SNR can also be computed by projections in this space.Results:The performance measure is validated by showing that it provides the Tapiovaara–Wagner optimal results for a detector with full energy information and also a conventional detector. The performance with different types of detectors is compared to the ideal SNR as a function of x‐ray tube voltage and subject thickness. A detector that combines two bin PHA with a simultaneous measurement of integrated photon energy provides near ideal performance across a wide range of operating conditions.Conclusions:Low energy resolution detectors can be used in energy selective x‐ray imaging systems to produce images with near optimal performance.