Search

Background/objectives: The concept of a general factor of collective intelligence, proposed by Woolley et al. in 2010, has spurred interest in understanding collective intelligence within small groups. This study aims to extend this investigation by examining the validity of a general collective intelligence factor, assessing its underlying factor structure, and evaluating its utility in predicting performance on future group problem-solving tasks and academic outcomes. Methods: Employing a correlational study design, we engaged 85 university students in a series of complex cognitive tasks designed to measure collective intelligence through individual, group, and predictive phases. Results: Contrary to the hypothesized single-factor model, our findings favor a two-factor model influenced by Cattell's theory of crystalized and fluid intelligence. These two factors accounted for substantial variance in group performance outcomes, challenging the prevailing single-factor model. Notably, the predictive validity of these factors on group assignments was statistically significant, with both individual and collective intelligence measures correlating moderately with group assignment scores (rs =.40 to.47, p <.05). Conclusions: Our research suggests that collective intelligence in small group settings may not be uniformly governed by a single factor but rather by multiple dimensions that reflect established theories of individual intelligence. This nuanced understanding of collective intelligence could have significant implications for enhancing group performance in both educational and organizational contexts. Future research should explore these dimensions and their independent contributions to group dynamics and outcomes. [ABSTRACT FROM AUTHOR]

Tungsten-181 is a middle energy radioisotope with an average energy of E avg =64.3keV and a half-life of T 1/2 =140d that holds promise as a new HDR brachytherapy source. This is because, except for its two highest energy photons which have energies of 136 keV (yield: 0.0311%) and 156 keV (yield: 0.0083%), this source is dominated by photons which lie between 56 keV to 67 keV. Such photons easily are absorbed by high Z materials but scatter readily in water. This study will investigate the treatment needs and intensity modulation capabilities of W-181 and compare these results to those of Iridium-192 and Ytterbium-169. Simulations were conducted using the Monte Carlo N-Particle Transport Code (MCNP6.2) to calculate the Dose Rate Constant, Radial Dose Function, photon self-absorption, and treatment activity of a 3.5mm long and 0.6mm diameter pellet encapsulated in stainless steel. We finally evaluated the intensity modulation capabilities of this pellet and compared it to Ir-192 and Yb-169. Our W-181 pellet had a Dose Rate Constant of 1.01 ± 0.01cGy∙h-1∙U-1 and a Radial Dose Function, which was fit to a 5th polynomial function to obtain the following coefficients: a 0 =9.01E-1 a 1 =8.60E-2 a 2 =2.96E-2 a 3 =-1.05E-2 a 4 =1.00E-3 a 5 =-3.00E-5. With respect to shielding and intensity modulation, 0.3mm of gold shielding reduced W-181's absorbed dose by 86%, Yb-169′s dose by 62%, and Ir-192's dose by 15%. While this isotope therefore can be an excellent candidate for IMBT, we also found that it is limited by a high photon self-absorption due to tungsten's very high density (19.3g/cm3) and atomic number (74). Specifically, we found that a W-181 pellet would provide an absorbed dose rate per unit activity of 1.84 ± 0.01cGy∙Ci-1min-1 to a treatment area 1cm from the source as opposed to Ir-192 and Yb-169's 31.0 ± 0.37 cGy∙Ci-1∙min-1 and 8.18 ± 0.11 cGy∙Ci-1∙min-1, respectively. A W-181 therapeutic source therefore would require a higher treatment activity than a Yb-169 or Ir-192 source. The capabilities of W-181 for intensity modulation outperforms that of Ir-192 and even Yb-169. Given these results, W-181 shows promise as a brachytherapy source, especially in multi-pellet configurations. [ABSTRACT FROM AUTHOR]

Inspired by a recent call for greater integration between histories of capitalism and of Indigenous peoples in the United States, I argue that scholars across American studies should take stock of the ways in which Indigenous history pertains to fields beyond economic history. This article emphasizes Indigenous agency and activism to historicize how Aboriginal history has become (somewhat) more prominent in American studies. In reviewing some of the literature that has helped bring about this still incomplete shift, I look at developments in the settler states of the United States and Canada in order to highlight their shared colonial structures. [ABSTRACT FROM AUTHOR]

Debates about US empire have subsided somewhat in the aftermath of the George W Bush presidency but the issues underlying such debates have not gone away. In arguing that the history of the United States is an imperial one, this article proposes that US empire is the expression of an intersectional totality, one shaped by various vectors of power but reducible to none. To make this case, the article presents a sketch of US imperial history in order to show how this intersectional totality has evolved over time. Such an exercise can give useful context to the foreign policy initiatives of the Barack Obama administration, one that differs from that of its immediate predecessor but is not outside the structure of imperial history’s longer duration. [ABSTRACT FROM PUBLISHER]

Purpose: A novel 32P brachytherapy source has been in use at our institution intraoperatively for temporary radiation therapy of the spinal dura and other localized tumors. We describe the dosimetry and clinical implementation of the source. Methods and Materials: Dosimetric evaluation for the source was done with a complete set of MCNP5 Monte Carlo calculations preceding clinical implementation. In addition, the depth dose curve and dose rate were measured by use of an electron field diode to verify the Monte Carlo calculations. Calibration procedures using the diode in a custom-designed phantom to provide an absolute dose calibration and to check dose uniformity across the source area for each source before treatment were established. Results: Good agreement was established between the Monte Carlo calculations and diode measurements. Quality assurance measurements results are provided for about 100 sources used to date. Clinical source calibrations were usually within 10% of manufacturer specifications. Procedures for safe handling of the source are described. Discussion: Clinical considerations for using the source are discussed. [ABSTRACT FROM AUTHOR]

Purpose: A novel 169Yb low dose rate permanent implant brachytherapy source, the GammaClip™, was developed by Source Production & Equipment Co. (New Orleans, LA) which is designed similar to a surgical staple while delivering therapeutic radiation. In this report, the brachytherapy source was characterized in terms of 'Dose calculation for photon-emitting brachytherapy sources with average energy higher than 50 keV: Report of the AAPM and ESTRO' by Perez-Calatayud et al. [Med. Phys. 39, 2904-2929 (2012)] using the updated AAPM Task Group Report No. 43 formalism. Methods: Monte Carlo calculations were performed using Monte Carlo N-Particle 5, version 1.6 in water and air, the in-air photon spectrum filtered to remove photon energies below 10 keV in accordance with TG-43U1 recommendations and previously reviewed 169Yb energy cutoff levels [D. C. Medich, M. A. Tries, and J. M. Munro, 'Monte Carlo characterization of an Ytterbium-169 high dose rate brachytherapy source with analysis of statistical uncertainty,' Med. Phys. 33, 163-172 (2006)]. TG-43U1 dosimetric data, including SK, D(r,θ), Λ, gL(r), F(r, θ), [lowercase_phi_synonym]an(r), and [lowercase_phi_synonym]an were calculated along with their statistical uncertainties. Since the source is not axially symmetric, an additional set of calculations were performed to assess the resulting axial anisotropy. Results: The brachytherapy source's dose rate constant was calculated to be (1.22 ± 0.03) cGy h-1 U-1. The uncertainty in the dose to water calculations, D(r,θ), was determined to be 2.5%, dominated by the uncertainties in the cross sections. The anisotropy constant, [lowercase_phi_synonym]an, was calculated to be 0.960 ± 0.011 and was obtained by integrating the anisotropy factor between 1 and 10 cm using a weighting factor proportional to r-2. The radial dose function was calculated at distances between 0.5 and 12 cm, with a maximum value of 1.20 at 5.15 ± 0.03 cm. Radial dose values were fit to a fifth order polynomial and dual exponential regression. Since the source is not axially symmetric, angular Monte Carlo calculations were performed at 1 cm which determined that the maximum azimuthal anisotropy was less than 8%. Conclusions: With a higher photon energy, shorter half-life and higher initial dose rate 169Yb is an interesting alternative to 125I for the treatment of nonsmall cell lung cancer. [ABSTRACT FROM AUTHOR]

Purpose: Absorbed dose energy correction factors, used to convert the absorbed dose deposited in a LiF thermoluminescent dosimeter (TLD) into the clinically relevant absorbed dose to water, were obtained for both spherical volumetric sources and for the model 4140 HDR Yb-169 source. These correction factors have a strong energy dependence below 200 keV; therefore, spectral changes were quantified as Yb-169 photons traveled through both source material (Yb2O3) and water with the corresponding absorbed dose energy correction factors, f(r,θ), calculated as a function of location in a phantom. Methods: Using the MCNP5 Monte Carlo radiation transport simulation program, the Yb-169 spectrum emerging from spherical Yb2O3 sources (density 6.9 g/cm3) with radii between 0.2 and 0.9 mm were analyzed and their behavior compared against those for a point-source. The absorbed dose deposited to both LiF and H2O materials was analyzed at phantom depths of 0.1–10 cm for each source radius and the absorbed dose energy correction factor calculated as the ratio of the absorbed dose to water to that of LiF. Absorbed dose energy correction factors for the Model 4140 Yb-169 HDR brachytherapy source similarly were obtained and compared against those calculated for the Model M-19 Ir-192 HDR source. Results: The Yb-169 average spectral energy, emerging from Yb2O3 spherical sources 0.2–0.9 mm in radius, was observed to harden from 7% to 29%; as these photons traveled through the water phantom, the photon average energy softened by as much as 28% at a depth of 10 cm. Spectral softening was dependent on the measurement depth in the phantom. Energy correction factors were found to vary both as a function of source radius and phantom depth by as much as 10% for spherical Yb2O3 sources. The Model 4140 Yb-169 energy correction factors depended on both phantom depth and reference angle and were found to vary by more than 10% between depths of 1 and 10 cm and angles of 0° and 180°. This was in contrast to that of the Model M-19 Ir-192 source which exhibited approximately 3.5%–4.4% variation in its energy correction factors from phantom depths of 0.5–10 cm. The absorbed dose energy correction factor for the Ir-192 source, on the other hand, was independent of angle to within 1%. Conclusions: The application of a single energy correction factor for Yb-169 TLD based dosimetry would introduce a high degree of measurement uncertainty that may not be reasonable for the clinical characterization of a brachytherapy source; rather, an absorbed dose energy correction function will need to be developed for these sources. This correction function should be specific to each source model, type of TLD used, and to the experimental setup to obtain accurate and precise dosimetric measurements. [ABSTRACT FROM AUTHOR]

The MCNP5 Monte Carlo code was used to simulate the dosimetry of an M-19 iridium-192 high dose rate brachytherapy source in both air/vacuum and water environments with the in-air photon spectrum filtered to remove low-energy photons below δ=10 keV. Dosimetric data was organized into an away-along table and was used to derive the updated AAPM Task Group Report No. 43 (TG-43U1) parameters including SK, D(r,θ), Λ, gL(r), F(r,θ), [lowercase_phi_synonym]an(r), and [lowercase_phi_synonym]an and their respective statistical uncertainties. [ABSTRACT FROM AUTHOR]

The differences between ecological restoration and other conservation and landscape management practices can be subtle or dramatic. I examine the basic tenets of ecological restoration and discuss ways that other practices could begin to achieve the goals of an ecological restoration project—the use of native species in an ecological community setting; recontouring of land to original site conditions; an emulation of historic reference sites; the use of local, natural materials for hardscaping; and many others. I also strongly encourage the use of the Society for Ecological Restoration International's Primer on Ecological Restoration and their Guidelines for Constructing and Managing Ecological Restoration Projects. Finally, I point out that there are numerous situations in which ecological restoration is impossible and should not be attempted. The best thing to do in these cases is to accept that fact, do the best job you can, and describe the project for whatever it is—just don't call it ecological restoration. [ABSTRACT FROM AUTHOR]

Books reviewed:Michael W. Klein, Scott Schuh, and Robert K. Triest,Job Creation, Job Destruction, and International CompetitionCarl Davidson and Steven J. Matusz,International Trade and Labor Markets: Theory, Evidence, and Policy ImplicationsWilliam R. Black,Transportation: A Geographical AnalysisBernard Fingleton,European Regional GrowthBernard Fingleton, Ayda Eraydin, and Raffaele Paci,Regional Growth, SMEs and the Wider EuropeJulia Traistaru, Peter Nijkamp, and Laura Resmini,The Emerging Economic Geography in EU Accession CountriesJohannes Bröcker, Dirk Dohse, and Rüdiger Soltwedel,Innovation Clusters and Interregional CompetitionAlan Hyde,Working in Silicon Valley: Economic and Legal Analysis of a High-Velocity Labor MarketRobert Mark Silverman,Community-Based Organizations: The Intersection of Social Capital and Local Context in Contemporary Urban SocietyWilliam A. V. Clark,Immigrants and the American Dream: Remaking the Middle ClassBarry G. Rabe,Statehouse and Greenhouse: The Emerging Politics of American Climate Change PolicyAmrita Daniere and Lois M. Takahashi,Rethinking Environmental Management in the Pacific Rim: Exploring Local Participation in Bangkok, ThailandCenter for Sustainable Environments, Northern Arizona University, with Terralingua and Grand Canyon Wildlands Council,Safeguarding the Uniqueness of the Colorado Plateau: An Ecoregional Assessment of Biocultural Diversity [ABSTRACT FROM AUTHOR]

Discusses why whiteness emerged as an analytical concept in US historiography beginning with David Roediger's 'The Wages of Whiteness: Race and the Making of the American Working Class' in 1999. This article surveys relevant literature and examines the usefulness of whiteness as a concept. Marxism laid the foundation for the Left's analyses of race, class, and economics; virtually every organization in the late 19th century (except the International Workers of the World) stressed class concerns over racial concerns. Max Shachtman's influential 'Communism and the Negro' (1933) argued that worker liberation would occur only after white workers championed the cause of blacks. The convergence of black radicalism and Marxism faltered during the early Cold War but reemerged during the late 1960's and 1970's and continued to influence scholarship through the turn of the 21st century.

In order to evaluate the impact of heavy exploitation on settlement and recruitment rates of coral reef fishes, the abundances of pre-settlement and pre-recruitment fishes were monitored at Discovery Bay, Jamaica, where fish stocks are heavily exploited and at several sites around the British Virgin Islands (BVI) where exploitation is moderate. Light traps set concurrently at Discovery Bay and at three fringing reefs in BVI caught many species of pre-settlement reef fishes, except grunts and parrotfish, and one BVI site (Hans Creek) may be an area of particularly high settlement. In contrast, heavily exploited fish stocks at Discovery Bay had greatly reduced settlement rates compared with all three sites in BVI. Settlement rates of unexploited species were more similar in Discovery Bay and BVI. Abundances of juvenile fish caught in wire-mesh traps were monitored over several years in Discovery Bay and at three sites in BVI. Consistently low numbers of exploited species were taken at Discovery Bay compared to the BVI sites, indicating that settlement and recruitment rates have been low in recent years. Exploited fish populations in the small marine protected area (MPA) at Discovery Bay are expected to increase very slowly as a result of settlement and recruitment limitation. [Copyright &y& Elsevier]

The present study examines the possibility that teacher knowledge about learning may have an impact on the effectiveness of a school. Thirty-two secondary qualified teachers engaged in a professional development program that provided a framework for reflective study of the learning process, analysis of key aspects of learning in their classes, and identification of the implications for teaching. Changes in teacher effectiveness were monitored in several ways: (1) changes in the display of effective teacher behaviours consistent with a social-constructivist model of learning, (2) changes in perceived ability to facilitate learning in classes, and (3) changes in student performance. The findings support the prediction that involvement in a systematic exploration of the learning process, with teachers explicating their knowledge of learning, has an direct impact, on the display of effective teaching behaviours and on teachers' personal explicit theory of learning. [ABSTRACT FROM AUTHOR]

Examines the relative advantages of urban and rural locations for cloth manufacturing in the medieval England and the Low Countries. Transition of the industry from urban to rural locations; Thesis on industrial location and guild strife in Flemish textile crafts; Industrial transformations in textile manufacturing.

Discusses the use of input-output information to measure the detail of the industrial structure of southern Italy and the linkages between different industrial sectors. Importance of structural change in economic development; Causes of changes in input-output coefficients; Overview of two-sector measures for backward linkage.

The article measures the space heating fuel consumption data for south-facing versus north-facing houses on opposite side of the same street. Measurements were made in a test site in San Jose, California during the winter of 1974-1975. The author explains that the purpose of this measurement is to find out whether savings in fuel consumption exists. He reports that the heating fuel consumption rates for the south-facing test houses are lower than those for the north-facing houses.

A preface for the book "Advances in Marine Biology," Volume 49, edited by Alan J. Southward, Craig M. Young and Lee A. Fuiman is presented.

Abstract: Purpose: To describe a novel source–delivery system for intraoperative brachytherapy in patients with early-stage lung cancer that is readily adaptable to a video-assisted thoracoscopic surgery approach and can be precisely delivered to achieve optimal dose distribution. Methods and Materials: Radioactive ytterbium-169 (169Yb) was sealed within a titanium tube 0.28mm in diameter and then capped and resealed by titanium wires laser welded to the tube to serve as the legs of a tissue-fastening system. Dose simulations were performed using Monte Carlo computer code (Los Alamos National Laboratory, Los Alamos, NM) to mimic the geometric and elemental compositions of the source, fastening apparatus, and surroundings. Results: Five test source capsules were subjected to a tensile load to failure. Failure in each capsule occurred in the wire of the fastener leg; there were no weld failures. Monte Carlo simulations and subsequent dose measurement showed the perturbation by the source legs in the deployed (bent over) position to be small (4–5%) for 169Yb and much less than that for iodine-125 (32%). Conclusion: We have developed a 169Yb brachytherapy source–delivery system that can be used in conjunction with commercially available surgical stapling instruments, facilitates the precise placement of brachytherapy sources relative to the surgical margin, assures the seeds remain fixed in their precise position for the duration of the treatment, overcomes the technical difficulties of manipulating the seeds through the narrow surgical incision associated with video-assisted thoracoscopic surgery, and reduces the radiation dose to the clinicians. [Copyright &y& Elsevier]

Purpose: To study the effects of the breast-air and breast-lung interfaces on the absorbed dose within the planning target volume (PTV) of a MammoSite® balloon dose delivery system as well as the effect of contrast material on the dose rate in the PTV. Methods: The Monte Carlo MCNP5 code was used to simulate dose rate in the PTV of a 2 cm radius MammoSite® balloon dose delivery system. The simulations were carried out using an average female chest phantom (AFCP) and a semi-infinite water phantom for both Yb-169 and Ir-192 high dose rate sources for brachytherapy application. Gastrografin was introduced at varying concentrations to study the effect of contrast material on the dose rate in the PTV. Results: The effect of the density of the materials surrounding the MammoSite® balloon containing 0% contrast material on the calculated dose rate at different radial distances in the PTV was demonstrated. Within the PTV, the ratio of the calculated dose rate for the AFCP and the semi-infinite water phantom for the point closest to the breast-air interface (90°) is less than that for the point closest to the breast-lung interface (270°) by 11.4% and 4% for the HDR sources of Yb-169 and Ir-192, respectively. When contrast material was introduced into the 2 cm radius MammoSite® balloon at varying concentrations, (5%, 10%, 15%, and 20%), the dose rate in the AFCP at 3.0 cm radial distance at 90° was decreased by as much as 14.8% and 6.2% for Yb-169 and Ir-192, respectively, when compared to that of the semi-infinite water phantom with contrast concentrations of 5%, 10%, 15%, and 20%, respectively. Conclusions: Commercially available software used to calculate dose rate in the PTV of a MammoSite® balloon needs to account for patient anatomy and density of surrounding materials in the dosimetry analyses in order to avoid patient underdose. [ABSTRACT FROM AUTHOR]

Radiochromic film dosimetry has been extensively used for intravascular brachytherapy applications for near field within 1 cm from the sources. With the recent introduction of new model of radiochromic films, GAFCHROMIC® EBT, with higher sensitivity than earlier models, it is promising to extend the distances out to 5 cm for low dose rate (LDR) source dosimetry. In this study, the use of new model GAFCHROMIC® EBT film for 125I seed dosimetry in Solid Water® was evaluated for radial distances from 0.06 cm out to 5 cm. A multiple film technique was employed for four 125I seeds (Implant Sciences model 3500) with NIST traceable air kerma strengths. Each experimental film was positioned in contact with a 125I seed in a Solid Water® phantom. The products of the air kerma strength and exposure time ranged from 8 to 3158 U-h, with the initial air kerma strength of 6 U in a series of 25 experiments. A set of 25 calibration films each was sequentially exposed to one 125I seed at about 0.58 cm distance for doses from 0.1 to 33 Gy. A CCD camera based microdensitometer, with interchangeable green (520 nm) and red (665 nm) light boxes, was used to scan all the films with 0.2 mm pixel resolution. The dose to each 125I calibration film center was calculated using the air kerma strength of the seed (incorporating decay), exposure time, distance from seed center to film center, and TG43U1S1 recommended dosimetric parameters. Based on the established calibration curve, dose conversion from net optical density was achieved for each light source. The dose rate constant was determined as 0.991 cGy U-1 h-1 (±6.9%) and 1.014 cGy U-1 h-1 (±6.8%) from films scanned using green and red light sources, respectively. The difference between these two values was within the uncertainty of the measurement. Radial dose function and 2D anisotropy function were also determined. The results obtained using the two light sources corroborated each other. We found good agreement with the TG43U1S1 recommended values of radial dose function and 2D anisotropy function, to within the uncertainty of the measurement. We also verified the dosimetric parameters in the near field calculated by Rivard using Monte Carlo method. The radial dose function values in Solid Water® were lower than those in water recommended by TG43U1S1, by about 2%, 3%, 7%, and 14% at 2, 3, 4, and 5 cm, respectively, partially due to the difference in the phantom material composition. Radiochromic film dosimetry using GAFCHROMIC® EBT model is feasible in determining 2D dose distributions around low dose rate 125I seed. It is a viable alternative to TLD dosimetry for 125I seed dose characterization. [ABSTRACT FROM AUTHOR]

Teacher knowledge is a critical factor in student success. In the Classroom Promotion of Oral Language cluster randomized controlled trial, we aimed to determine whether a teacher professional learning intervention focused on promoting oral language led to improved teacher knowledge. We report a study of the impact of professional learning on teacher knowledge of oral language and literacy constructs. The intervention comprised four days of face-to-face professional learning for early years' teachers, and ongoing school implementation support. Teacher knowledge was measured through a survey at baseline, 12 months and 24 months (n = 40 intervention, n = 38 control). Teachers in the intervention arm made more correct responses on survey items than teachers in the control arm, at both time points. The professional learning intervention improved teacher knowledge in the short-to-medium term. [ABSTRACT FROM AUTHOR]