bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functionally Localizing Language‐Sensitive Regions in Individual Subjects With fMRI: A Reply to Grodzinsky’s Critique of Fedorenko and Kanwisher (2009)
Authors: Fedorenko Evelina , Kanwisher Nancy 
Published: February 2011

AbstractIn Fedorenko and Kanwisher (F&K 2009), we argued that defining regions of interest functionally in individual subjects may lead to a clearer picture of the functional architecture of the language system because it affords higher sensitivity and selectivity. Grodzinsky (2010) takes issue with two aspects of the F&K paper. First, he argues that the picture of the neural basis of language that has emerged from previous work is not as murky as F&K argue, with the implication that perhaps a new method is not needed. And second, he raises some concerns with the individual‐subjects functional localization approach and argues instead for the use of probabilistic cytoarchitectonic maps (e.g., Amunts et al. 1999). In the current manuscript, we respond to both of Grodzinsky’s points. Regarding the first point, we stand by our assessment of the brain basis of language literature, and argue that many core questions related to functional specialization remain unanswered. We explain why we remain unconvinced by Grodzinsky’s example of Broca’s area (or a portion of it) as a region with a well‐understood functional profile. Regarding the concerns that Grodzinsky raises with respect to the use of functional localizers in investigating the language system, we respond to the main comments and refer the reader to Fedorenko et al. (2010) where the remaining concerns are addressed (with both data and argumentation). Finally, we point out that the probabilistic cytoarchitectonic maps that Grodzinsky advocates have some of the same limitations as other group‐based methods. We conclude that the individual‐subjects functional localization approach, advocated in F&K, holds promise for better understanding the brain basis of language by enabling a detailed characterization of language‐sensitive regions with respect to their role in both linguistic and non‐linguistic processes.
Leveraging Motivational Mindsets to Foster Positive Interracial Interactions
Authors: Murphy Mary C. , Richeson Jennifer A. , Molden Daniel C. 
Published: February 2011

AbstractAs the United States becomes increasingly diverse, interracial contact will become considerably less rare. Much research has suggested that interracial interactions are often stressful and uncomfortable for both Whites and racial minorities. Bringing together several bodies of research, the present article outlines a motivational perspective on the dynamics of intergroup contact. To this end, we consider the roles of three motivational mindsets that have the potential to shape interactions to be less cognitively depleting and more enjoyable for both interactants. In particular, we consider the effects of (i) approach and avoidance motivation (Handbook of Motivation and Cognition: Foundation of Social Behavior, 1990, New York: Guilford Press), (ii) promotion and prevention regulatory focus (American Psychologist, 52, 1997, 1280), and (iii) learning and performance goals (Psychological Review, 95, 1988, 256) in shaping the dynamics of interracial contact. We suggest that investigations into these motivational mindsets will offer further insight into how and why interracial interactions go awry and will assist in the development of strategies and interventions that facilitate more smooth and enjoyable contact experiences.
Positivism and ‘Functional Theory’ in the Thought of Karl Polanyi, 1907–1922
Authors: Dale Gareth 
Published: February 2011

AbstractKarl Polanyi is the author of a modern social science classic, The Great Transformation, as well as a number of well‐known and widely debated essays collected in Trade and Market in the Early Empires and Primitive, Archaic and Modern Economies. These texts were researched and written either during his second exile in 1930s Britain or in wartime or post‐war North America. Not so well known, however, are his Hungarian writings from the 1910s. Until recently, very few of these had been republished or translated, although this is in the process of being rectified [Gareth Dale (forthcoming): Karl Polanyi: The Hungarian Writings]. With reference to new translations of his Hungarian writings, to interviews with his daughter, Kari Polanyi‐Levitt, as well as to biographical essays by György Litván, Évá Gábor, Endre Kiss, and Zoltán Horváth, this article explores his early influences, drawing attention in particular to his flirtation with and then violent reaction against philosophical materialism and ‘objectivist’ sociology, his appreciation of Ernst Mach’s positivism, and his adherence to the ‘functional theory’ of contemporary Guild Socialism.
The Role of Social Networks in Getting a Job
Authors: Trimble Lindsey B. , Kmec Julie A. 
Published: February 2011

AbstractThis article reviews recent research on the effects of social networks on access to job information and getting a job in the United States. Drawing on network ties from friends, family members, acquaintances, employers, or coworkers can improve the job search because individuals gain access to and make use of their network’s social capital. While this job searching strategy can result in a successful job search for some, not all job seekers benefit from reliance on social networks. We spotlight research that documents how reliance on social networks as a means to find work can actually maintain sex and racial/ethnic inequality at work. We discuss research documenting the important role social networks play in the job acquisition process. The last half of this review focuses on several new developments in the literature that promise to further our understanding of social networks’ lasting effects on employment outcomes.
The central electrode correction factor for high‐Z electrodes in small ionization chambers
Authors: Muir B. R. , Rogers D. W. O. 
Published: February 2011

Purpose:Recent Monte Carlo calculations of beam quality conversion factors for ion chambers that use high‐Z electrodes [B. R. Muir and D. W. O. Rogers, Med. Phys., – (2010)] have shown large deviations of values from values calculated using the same techniques as the TG‐51 and TRS‐398 protocols. This report investigates the central electrode correction factor, , for these chambers.Methods:Ionization chambers are modeled and is calculated using the EGSnrc user code egs_chamber for three cases: in photon and electron beams under reference conditions; as a function of distance from an iridium‐192 point source in a water phantom; and as a function of depth in a water phantom on which a 200 kVp x‐ray source or 6 MV beam is incident.Results:In photon beams, differences of up to 3% between calculations for a chamber with a high‐Z electrode and those used by TG‐51 for a 1 mm diameter aluminum electrode are observed. The central electrode correction factor for a given value of the beam quality specifier is different depending on the amount of filtration of the photon beam. However, in an unfiltered 6 MV beam, , varies by only 0.3% for a chamber with a high‐Z electrode as the depth is varied from 1 to 20 cm in water. The difference between calculations for chambers with high‐Z electrodes and TG‐51 values for a chamber with an aluminum electrode is up to 0.45% in electron beams. The central electrode correction, which is roughly proportional to the chambers absorbed dose sensitivity, is found to be large and variable as a function of distance for chambers with high‐Z and aluminum electrodes in low‐energy photon fields.Conclusions:In this work, ionization chambers that employ high‐Z electrodes have been shown to be problematic in various situations. For beam quality conversion factors, the ratio of in a beam quality to that in a Co‐60 beam is required; for some chambers, is significantly different from current dosimetry protocol values because of central electrode effects. It would be best for manufacturers to avoid producing ion chambers that use high‐Z electrodes.
Stochastic formulation of patient positioning using linac‐mounted cone beam imaging with prior knowledge
Authors: Hoegele W. , Loeschel R. , Dobler B. , Hesser J. , Koelbl O. , Zygmanski P. 
Published: February 2011

Purpose:In this work, a novel stochastic framework for patient positioning based on linac‐mounted CB projections is introduced. Based on this formulation, the most probable shifts and rotations of the patient are estimated, incorporating interfractional deformations of patient anatomy and other uncertainties associated with patient setup.Methods:The target position is assumed to be defined by and is stochastically determined from positions of various features such as anatomical landmarks or markers in CB projections, i.e., radiographs acquired with a CB‐CT system. The patient positioning problem of finding the target location from CB projections is posed as an inverse problem with prior knowledge and is solved using a Bayesian maximuma posteriori (MAP) approach. The prior knowledge is three‐fold and includes the accuracy of an initial patient setup (such as in‐room laser and skin marks), the plasticity of the body (relative shifts between target and features), and the feature detection error in CB projections (which may vary depending on specific detection algorithm and feature type). For this purpose, MAP estimators are derived and a procedure of using them in clinical practice is outlined. Furthermore, a rule of thumb is theoretically derived, relating basic parameters of the prior knowledge (initial setup accuracy, plasticity of the body, and number of features) and the parameters of CB data acquisition (number of projections and accuracy of feature detection) to the expected estimation accuracy.Results:MAP estimation can be applied to arbitrary features and detection algorithms. However, to experimentally demonstrate its applicability and to perform the validation of the algorithm, a water‐equivalent, deformable phantom with features represented by six 1 mm chrome balls were utilized. These features were detected in the cone beam projections (XVI, Elekta Synergy®) by a local threshold method for demonstration purposes only. The accuracy of estimation (strongly varying for different plasticity parameters of the body) agreed with the rule of thumb formula. Moreover, based on this rule of thumb formula, about 20 projections for 6 detectable features seem to be sufficient for a target estimation accuracy of 0.2 cm, even for relatively large feature detection errors with standard deviation of 0.5 cm and spatial displacements of the features with standard deviation of 0.5 cm.Conclusions:The authors have introduced a general MAP‐based patient setup algorithm accounting for different sources of uncertainties, which are utilized as the prior knowledge in a transparent way. This new framework can be further utilized for different clinical sites, as well as theoretical developments in the field of patient positioning for radiotherapy.
Comparative imaging study in ultrasound, MRI, CT, and DSA using a multimodality renal artery phantom
Authors: King Deirdre M. , Fagan Andrew J. , Moran Carmel M. , Browne Jacinta E. 
Published: February 2011

Purpose:A range of anatomically realistic multimodality renal artery phantoms consisting of vessels with varying degrees of stenosis was developed and evaluated using four imaging techniques currently used to detect renal artery stenosis (RAS). The spatial resolution required to visualize vascular geometry and the velocity detection performance required to adequately characterize blood flow in patients suffering from RAS are currently ill‐defined, with the result that no one imaging modality has emerged as a gold standard technique for screening for this disease.Methods:The phantoms, which contained a range of stenosis values (0%, 30%, 50%, 70%, and 85%), were designed for use with ultrasound, magnetic resonance imaging, x‐ray computed tomography, and x‐ray digital subtraction angiography. The construction materials used were optimized with respect to their ultrasonic speed of sound and attenuation coefficient, MR relaxometry properties, and Hounsfield number/x‐ray attenuation coefficient, with a design capable of tolerating high‐pressure pulsatile flow. Fiducial targets, incorporated into the phantoms to allow for registration of images among modalities, were chosen to minimize geometric distortions.Results:High quality distortion‐free images of the phantoms with good contrast between vessel lumen, fiducial markers, and background tissue to visualize all stenoses were obtained with each modality. Quantitative assessments of the grade of stenosis revealed significant discrepancies between modalities, with each underestimating the stenosis severity for the higher‐stenosed phantoms (70% and 85%) by up to 14%, with the greatest discrepancy attributable to DSA.Conclusions:The design and construction of a range of anatomically realistic renal artery phantoms containing varying degrees of stenosis is described. Images obtained using the main four diagnostic techniques used to detect RAS were free from artifacts and exhibited adequate contrast to allow for quantitative measurements of the degree of stenosis in each phantom. Such multimodality phantoms may prove useful in evaluating current and emerging US, MRI, CT, and DSA technology.
Metal artifact reduction in x‐ray computed tomography (CT) by constrained optimization
Authors: Zhang Xiaomeng , Wang Jing , Xing Lei 
Published: February 2011

Purpose:The streak artifacts caused by metal implants have long been recognized as a problem that limits various applications of CT imaging. In this work, the authors propose an iterative metal artifact reduction algorithm based on constrained optimization.Methods:After the shape and location of metal objects in the image domain is determined automatically by the binary metal identification algorithm and the segmentation of “metal shadows” in projection domain is done, constrained optimization is used for image reconstruction. It minimizes a predefined function that reflectsa priori knowledge of the image, subject to the constraint that the estimated projection data are within a specified tolerance of the available metal‐shadow‐excluded projection data, with image non‐negativity enforced. The minimization problem is solved through the alternation of projection‐onto‐convex‐sets and the steepest gradient descent of the objective function. The constrained optimization algorithm is evaluated with a penalized smoothness objective.Results:The study shows that the proposed method is capable of significantly reducing metal artifacts, suppressing noise, and improving soft‐tissue visibility. It outperforms the FBP‐type methods and ART and EM methods and yields artifacts‐free images.Conclusions:Constrained optimization is an effective way to deal with CT reconstruction with embedded metal objects. Although the method is presented in the context of metal artifacts, it is applicable to general “missing data” image reconstruction problems.
Scaling law for noise variance and spatial resolution in differential phase contrast computed tomography
Authors: Chen Guang‐Hong , Zambelli Joseph , Li Ke , Bevins Nicholas , Qi Zhihua 
Published: February 2011

Purpose:The noise variance versus spatial resolution relationship in differential phase contrast (DPC) projection imaging and computed tomography (CT) are derived and compared to conventional absorption‐based x‐ray projection imaging and CT.Methods:The scaling law for DPC‐CT is theoretically derived and subsequently validated with phantom results from an experimental Talbot–Lau interferometer system.Results:For the DPC imaging method, the noise variance in the differential projection images follows the same inverse‐square law with spatial resolution as in conventional absorption‐based x‐ray imaging projections. However, both in theory and experimental results, in DPC‐CT the noise variance scales with spatial resolution following an inverse linear relationship with fixed slice thickness.Conclusions:The scaling law in DPC‐CT implies a lesser noise, and therefore dose, penalty for moving to higher spatial resolutions when compared to conventional absorption‐based CT in order to maintain the same contrast‐to‐noise ratio.
Quality assurance of volumetric modulated arc therapy: Evaluation and comparison of different dosimetric systems
Authors: Masi L. , Casamassima F. , Doro R. , Francescon P. 
Published: February 2011

Purpose:To compare and evaluate different dosimetric techniques and devices for the QA of VMAT plans created by two treatment planning systems (TPSs).Methods:A total of 50 VMAT plans were optimized for treatment of anatomical sites of various complexities by two TPSs which use rather different approaches to VMAT optimization. Dosimetric plan verifications were performed both as part of commissioning and as patient specific QA of clinical treatments. Absolute point doses were measured for all plans by a micro ion chamber inserted in a dedicated water‐filled cylindrical phantom. Delivered dose distributions were verified by four techniques based on different detectors: radiographic and gafchromic films, two systems based on 2D diode arrays and an ion chamber array. Gamma index analysis with various tolerance levels (3%, 3 mm and 3%, 2 mm) was used to analyze differences between calculated and delivered doses. Sensitivity to possible delivery errors was also evaluated for three of the considered devices introducing ±3 mm shifts along the three directions and a 3° gantry offset.Results:Ion chamber measured point doses were within 3% of calculated ones for 48 out of 50 values. For delivered dose distribution, the average fraction of passed gamma values using 3% and 3 mm criteria was above 95% for both TPSs and all detectors except gafchromic film which yielded on average of 91.4%. For 49 out of 50 plans, a pass‐rate above 94% was obtained by at least one of the four techniques. Shrinking the tolerance to 3% and 2 mm, the average pass‐rate by all detectors (except film) was still above 95% for one of the two TPSs, but lower for the other one. The detector sensitivity to 3 mm shifts and to gantry angle offset was strongly plan and partially detector dependent: the obtained pass‐rate reduction ranged from 2% to 30%.Conclusions:The presented results for VMAT plans QA assess the reliability of the delivered doses for both TPSs. The slightly lower pass‐rate obtained for one of the considered TPS can be attributed to a higher level of complexity of the optimized plans. The results by different dosimetric techniques are coherent, apart from a few measurements by gafchromic films. The detector sensitivity to delivery errors, being strongly plan dependent, is not easy to evaluate.
Application of thermography for the assessment of allergen‐induced skin reactions
Authors: Rokita Eugeniusz , Rok Tomasz , Tatoń Grzegorz 
Published: February 2011

Purpose:The allergic response is commonly identified and assessed by skin testing. The usual method to quantify skin reactions is to mark wheal and erythema regions and assess the surfaces affected by the reactions; however, subjective interpretation of the outcome may cause errors. Skin thermography supplemented by a mathematical model based on the pathophysiology of heat generation was evaluated as a novel, objective, and sensitive indicator of the skin prick test result.Methods:TH measurements were performed simultaneously with routine skin prick tests for 24 patients. Eight allergens and control (histamine) were examined. Thermographic images of both forearms were acquired every 70 s from 0 to 910 s after skin prick and analyzed with the use of dedicated software. The introduction of potential allergens and histamine at sites on the skin induces a complex sequence of events known as the local inflammatory response. The crucial steps of the process have been considered in the model. In the model, the authors assumed that the reaction takes place in the thin skin layer and that histamine is the principal mediator of the allergic reaction. Histamine penetrates the skin and binds to receptors of nearby capillaries and venules. The engorged vessels are, in turn, responsible for skin redness and an increase in skin temperature.Results:The model parameters were determined by fitting the analytical solutions to the spatiotemporal distributions of the differences between measured and baseline temperatures. The model reproduces experimental data very well. The coefficient of determination ranged from 0.805 to 0.995. Seven model parameters were tested to find the optimal marker of the intensity and kinetics of the allergic reaction. The parameter which quantifies a release of histamine after allergen injection has appeared to be the best indicator of the allergen‐induced response. The parameter correlates with the routine assessment based on wheal and erythema areas (correlation).Conclusions:It was demonstrated that the thermographic measurements supplemented by the mathematical model offer a new approach to the quantification of allergen‐induced skin reactions. Despite the applied simplifications, the proposed model reflected properly the mechanism of heat generation during skin prick test. Moreover, the continuous recording of the skin temperature represents an additional possibility to investigate the mechanism of the allergic reaction.
Characterization of image quality and image‐guidance performance of a preclinical microirradiator
Authors: Clarkson R. , Lindsay P. E. , Ansell S. , Wilson G. , Jelveh S. , Hill R. P. , Jaffray D. A. 
Published: February 2011

Purpose:To assess image quality and image‐guidance capabilities of a cone‐beam CT based small‐animal image‐guided irradiation unit (micro‐IGRT).Methods:A micro‐IGRT system has been developed in collaboration with the authors' laboratory as a means to study the radiobiological effects of conformal radiation dose distributions in small animals. The system, the X‐Rad 225Cx, consists of a 225 kVp x‐ray tube and a flat‐panel amorphous silicon detector mounted on a rotational C‐arm gantry and is capable of both fluoroscopic x‐ray and cone‐beam CT imaging, as well as image‐guided placement of the radiation beams. Image quality (voxel noise, modulation transfer, CT number accuracy, and geometric accuracy characteristics) was assessed using water cylinder and micro‐CT test phantoms. Image guidance was tested by analyzing the dose delivered to radiochromic films fixed to BB's through the end‐to‐end process of imaging, targeting the center of the BB, and irradiation of the film/BB in order to compare the offset between the center of the field and the center of the BB. Image quality and geometric studies were repeated over a 5–7 month period to assess stability.Results:CT numbers reported were found to be linear and the noise for images of homogeneous water phantom was 30 HU at imaging doses of approximately 1 cGy (to water). The presampled MTF at 50% and 10% reached 0.64 and , respectively. Targeting accuracy by means of film irradiations was shown to have a mean displacement error of , with standard deviations of [0.02, 0.20, 0.17] mm. The system has proven to be stable over time, with both the image quality and image‐guidance performance being reproducible for the duration of the studies.Conclusions:The micro‐IGRT unit provides soft‐tissue imaging of small‐animal anatomy at acceptable imaging doses. The geometric accuracy and targeting systems permit dose placement with submillimeter accuracy and precision. The system has proven itself to be stable over 2 yr of routine laboratory use and provides a platform for the exploration of targeted radiation effects in small‐animal models.