This work presents a spreadsheet that calculates the mole fractions of end-member components for simple Na-Ca-Li-Mg-Fe2+-Al tourmalines from electron microprobe data. The input includes the B2O3 ...concentration obtained either from direct analysis or by estimation on the basis of stoichiometry. The concentration of Li2O can either be input from other analysis or estimated by the spreadsheet. The spreadsheet does not address the mole fractions of Cr, V, oxidized or deprotonated tourmaline species, nor account for species involving tetrahedral boron or aluminum. Therefore, the spreadsheet is not a comprehensive tool that includes all IMA approved tourmaline species, and so is not intended for naming tourmalines according to IMA convention. The present method includes a useful subset of end-member species that can be described simply from electron microprobe data and so, akin to a normative mineralogical analysis for rock composition, the calculations are intended to provide a normative result that serves as simple basis for comparing tourmalines that is more direct than names derived from the most abundant species present.
A series of electrically conducting metal oxides with the pyrochlore structure (A 2 B 2 O 7−y , with A = Pb or Bi and B = Ru, Ir or Os) were synthesized via precipitation/crystallization in alkaline ...medium and/or via solid-state reaction. The electrocatalytic activity for the oxygen evolution reaction (OER) in 0.1 M KOH was studied using a rotating disk electrode. Lead and bismuth ruthenate pyrochlores showed significantly lower overpotentials for the OER than the state-of-the-art IrO 2 catalyst. Specific activities (at 1.5 V vs. RHE) of 3.0 ± 0.2 A m −2 , 1.3 ± 0.2 A m −2 and 0.06 ± 0.01 A m −2 were obtained for Pb 2 Ru 2 O 6.5 , Bi 2.4 Ru 1.6 O 7 , and IrO 2 respectively. Specific activities for iridate-based pyrochlores (0.3–0.5 A m −2 ) were 5–10 times lower than those for ruthenate-based pyrochlores. Lead osmate pyrochlore showed the lowest OER activity among all the pyrochlores evaluated, with a specific activity of 0.10 ± 0.07 A m −2 . It is proposed that the reaction path for the OER involves several oxygen intermediate species (–O 2− , –OOH, –OO 2− , –OH) bonded to the B-site (Ru, Ir or Os) in the pyrochlore, and that the catalytic activity depends on the bonding strength between the B-cation site and the oxygen species. This hypothesis was supported by the fact that OER activity correlated with Ru concentration in lead-rich lead ruthenate pyrochlores. The decrease of the specific OER activity depended on the occupancy of the 3d orbitals and on the period in the periodic table occupied by the B-cation. The OER activity decreased for pyrochlores with B cations having more d electrons than Ru, and when the B cation occupied period 6. The observed trend in activity was similar to that observed for the oxygen reduction reaction on transition metals, and was related to the strength of the bonding between the adsorbed oxygen species and the B-cation. The exceptional OER activity and stability of lead ruthenate pyrochlore catalysts were evaluated in a solid-state alkaline water electrolyzer. The overpotentials obtained were 0.1–0.2 V lower than for IrO 2 and the performance was stable for at least 200 h.
In a previous work (Morgan and London 1996), we proposed an optimized procedure for electron microprobe analysis (EMPA) of rhyolitic glasses using a broad (20 µm diameter), low-current (2 nA) fixed ...beam. Some important applications for EMPA of glass, such as vitreous inclusions in minerals and experimental run products, require smaller beam diameters that produce greater areal current densities (expressed as nA/µm2). For these situations, we have assessed the effect of areal current density on the migration of Na and its concomitant effects on other elements and their ratios during EMPA of granitic glasses. Anhydrous and hydrous glasses of a haplogranite composition (Ab38.23 Or29.31 Qtz33.37 C0.10) were analyzed at 20 kV accelerating potential, using 2-50 nA beam currents, fixed beam diameters of 2-20 µm, and counting times scaled to yield similar analytical uncertainty at each condition (approximately 2.6% relative for Na2O). There is almost no loss of Na (≤1.7-2.7% relative) using a current density of 0.006 nA/µm2, minor (7-9%) Na loss for current densities up to 0.1 nA/µm2, and increasing Na loss with higher current densities that becomes severe at >0.5 nA/µm2 (e.g., 48-63% relative loss from hydrous glass at 50 nA and 2 µm during 3-6 s of irradiation). Sodium migration is more pronounced in hydrous glasses than in anhydrous ones, with significant loss from hydrous glass occurring during the first second of irradiation. The migration of Na results in increased concentrations of Al and Si, but little or no change in the concentration of K; if not fully corrected for, these effects produce systematic errors in important elemental ratios. With current densities <0.01 nA/µm2, anhydrous glasses or crystalline materials are suitable standards and data correction may not be needed. Significant Na loss using current densities up to ∼0.1-0.2 nA/µm2, especially in hydrous glasses, requires data correction or primary standardization utilizing a glass having composition and water content similar to the unknown. Current densities ≥0.5-1.0 nA/µm2 are not suitable for EMPA of glass because of large and uncertain corrections (∼25% to >100% of the Na2O value obtained). The correlation of analytical condition (beam current and diameter) with current density and EMPA results provided here allows analysts to select beam conditions that optimize the quality of analyses. When current densities ∼0.01 nA/µm2 must be used (e.g., with beam spot sizes <20 µm), the results can lead to improved estimates of the systematic errors due to alkali migration. Natural and some experimental glasses contain a variety of other minor components among which Ca and Fe are important, and so the discussion of analytical methods is extended to more complex compositions. For example, Na migration is accelerated as glass structures become less polymerized than those of simple tectosilicate stoichiometry (e.g., due to increasing alkalinity and/or the presence of fluxing components such as F, Cl, B). Analysis using 20 kV accelerating voltage, as opposed to 15 kV, both slightly decreases Na migration and improves limits of detection and statistical accuracies for minor components such as Fe while providing reasonable beam penetration depths.
Global optometrist top 200 research ranking Efron, Nathan; Morgan, Philip B; Jones, Lyndon W ...
Clinical and experimental optometry,
05/2021, Letnik:
104, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Clinical optometric practice is underpinned by a rigorous research base, the primary evidence for which is publications in refereed scientific journals. Leading optometrists who publish this work ...should be identified and celebrated.
This work aims to derive publication metrics of the leading optometric researchers worldwide.
Methods: An extensive global search was conducted to discover leading optometric researchers; 480 names were identified. A custom-designed bibliographic search tool was developed to interrogate the Scopus database (Elsevier) and extract publication metrics using the unique Scopus Author Identifier number for each optometrist. On 13 January 2021, the full list was reduced to 200 optometrists (the 'Top 200') ranked by h-index - the 'Global Optometrist Top 200 Research Ranking'. The output from the custom tool automatically updates every 24 hours and is available at
www.optomrankings.com
.
The Top 200 have h-indices ranging from 20 to 67 and have published between 28 and 440 papers. Sixty one (30.5%) are women. Konrad Pesudovs has the highest h-index (67) and citations (51,193). The most prolific author is Robert Hess (442 papers). David Piñero is publishing at the fastest rate (17.6 papers per year). The Top 200 work in 13 nations, of whom 172 (86.0%) work in four nations: USA - 76 (38.0%), Australia - 43 (21.5%), UK - 41 (20.5%) and Canada - 16 (8.0%). Of the 72 institutions represented, the University of California, Berkeley, USA is home to the most Top 200 optometrists (17) and has the highest combined h-index of Top 200 optometrists (132).
The optometric profession is supported by a robust research base, prosecuted by a large international cohort of optometric researchers who publish extensively on a broad range of ophthalmic issues and whose work is highly cited. The 200 most impactful optometrists in the world are identified.
Sickle cell disease (SCD) is an inherited, progressively debilitating blood disorder. Emerging gene therapies (GTx) may lead to a complete remission, the benefits of such can only be realized if GTx ...is affordable and accessible in the low-and middle-income countries (LMIC) with the greatest SCD burden. To estimate the health impacts and country-specific value-based prices (VBP) of a future gene therapy for SCD using a cost-utility model framework. We developed a lifetime Markov model to compare the costs and health outcomes of GTx versus standard of care for SCD. We modeled populations in seven LMICs and six high-income countries (HICs) estimating lifetime costs and disability-adjusted life-years (DALYs) in comparison to estimates of a country's cost-effectiveness threshold. Each country's unique VBP for GTx was calculated via threshold analysis. Relative to SOC treatment alone, we found that hypothetical GTx reduced the number of people symptomatic with SCD over time leading to fewer DALYs. Across countries, VBPs ranged from $3.6 million (US) to $700 (Uganda). Our results indicate a wide range of GTx prices are required if it is to be made widely available and may inform burden and affordability for 'target product profiles' of GTx in SCD.
Likert type scales are commonly used in social sciences. Most of the Likert scales include both positively- and negatively worded items. However, the use of negatively worded (reversed) items is ...supported by some researchers but not others. This study analyzes the reversed items in educational settings. The school age, self-rating version of the Dimensions of Mastery Questionnaire (DMQ 17) was used. The sample consisted of 7261 Hungarian students, age 10 to 16. An iteration method was developed and used to filter our presumably invalid responders. The analysis is based on the empirical inconsistency between the reversed and the positively worded items. The iteration eliminated step-by-step the possibly invalid questionnaires. The reliabilities of the scales were increased with the iteration process. After eliminating about 20% of the sample, the reliabilities were somewhat higher with all scales having acceptable alphas. If one would like to use this iteration method for eliminating the invalid responders, he or she needs to oversample the accessible population. Based on this results we eliminated the reversed items form the new DMQ persistence and pleasure scales.
Haemophilia A is a bleeding disorder caused by deficiency of coagulation factor VIII (FVIII) which leads to severe and repeated bleedings. There is a need to understand the optimal treatment pathway ...for FVIII inhibitors with the use of immune tolerance induction (ITI) and the role of haemostatic 'bypassing' agents (BPA) on-demand (OD) or prophylactically (Px). The aim of this study was to gain a better understanding of the real-world use of BPA therapy administered prophylactically or on-demand concomitant with ITI, for the treatment of an inhibitor to FVIII replacement therapy in patients with severe haemophilia A.
Retrospective observational data were used to capture disease management information for patients who were aged 16 or under and had received ITI and BPA treatment for their most recent inhibitor from Jan-2015 to Jan-2019, for 47 patients in the UK and Germany. Descriptive comparisons of the clinical effectiveness and resource utilisation of Px and OD BPA therapy during ITI were conducted.
During ITI and BPA treatment, for an inhibitor, bleeding events averaged 1.5 and 1.2 for Px and OD treatment respectively. Compared to only BPA therapy we see 3.4 and 1.4 bleeding events for Px and OD respectively during an inhibitor.
Baseline disease characteristics differed between BPA therapy cohorts and this resulted in higher clinical effectiveness of ITI treatment alongside BPA Px than BPA OD during an inhibitor.
ObjectivesThe benefits of minimally invasive surgery (MIS) for endometrial carcinoma (EC) are well established although the financial impact of robotic-assisted hysterectomy (RH) compared with ...laparoscopic hysterectomy (LH) is disputed.DesignRetrospective cohort study.SettingEnglish National Health Service hospitals 2011–2017/2018.Participants35 304 women having a hysterectomy for EC identified from Hospital Episode Statistics.Primary and secondary outcome measuresThe primary outcome was the association between route of surgery on cost at intervention, 30, 90 and 365 days for women undergoing an open hysterectomy (OH) or MIS (LH/RH) for EC in England. The average marginal effect was calculated to compare RH versus OH and RH versus LH which adjusted for any differences in the characteristics of the surgical approaches. Secondary outcomes were to analyse costing data for each surgical approach by age, Charlson Comorbidity Index (CCI) and hospital MIS rate classification.ResultsA total of 35 304 procedures were performed, 20 405 (57.8%) were MIS (LH: 18 604 and RH: 1801), 14 291 (40.5%) OH. Mean cost for LH was significantly less than RH, whereas RH was significantly less than OH at intervention, 30, 90 and 365 days (p<0.001). Over time, patients who underwent RH had increasing CCI scores and by the 2015/2016 year had a higher average CCI than LH. Comparing the cost of LH and RH against CCI score identified that the costs closely reflected the patients’ CCI. Increasing disparity was also seen between the MIS and OH costs with rising age. When exploring the association between provider volume, MIS rate and surgical costs, there was an association with the higher the MIS rate the lower the average cost.ConclusionsFurther research is needed to investigate costs in matched patient cohorts to determine the optimum surgical modality in different populations.
This paper explores the identity work taking place around contemporary subcultural hip hop amongst Australian indigenous youth in two disadvantaged urban locations. Previous work on Aboriginal hip ...hop has been attentive to the interface between tradition and modernity. However, existing scholarship has lacked a deeper ethnographic understanding of the dynamics between youth and parent cultures, and the tensions between the two generations. This article is based on research with young hip hop enthusiasts, community activists and educators. It deals with the cultural politics of identification and sees hip hop practice as associated with a process in which Aboriginality is crystallized as a principal affiliation and as offering an account for experiences of social marginalization. Far from being an outlet for expressing a prior or essential Aboriginality, hip hop as cultural practice is associated with the production of particular identifications.
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