Understanding the role of promoters in catalysis: operando XAFS/DRIFTS study of CeO_x/Pt/Al₂O₃ during CO oxidation

A combined operando XAFS/DRIFTS study on CeOx/Pt/Al2O3 catalysts has been performed during CO oxidation and provides insights into the changes in nanoparticle structure and adsorbed species during the reaction profile. The onset of CO2 formation is shown to be concurrent with a rapid re-oxidation of the Pt nanoparticles, evidenced by XAFS spectroscopy, and the loss of bridge bonded CO adsorbed on Pt, as shown by simultaneous DRIFTS acquisition. The continued appearance of linear bound CO on the catalyst surface is shown to remain long after catalytic light off. The interaction of Pt and CeOx is evidenced by the improved performance towards CO oxidation, compared to the non-CeOx modified Pt/Al2O3, and changes in the CO adsorption properties on Pt previously linked to Pt-CeO2 interfaces

Sum rules for spin asymmetries

Starting from rotational invariance we derive sum rules for the single-spin asymmetries in inclusive production and binary processes. We also get sum rules for spin correlation parameters in elastic pp-scattering.Comment: 4 page

High precision determination of the Q2Q^2-evolution of the Bjorken Sum

We present a significantly improved determination of the Bjorken Sum for 0.6$\leq Q^{2}\leq$4.8 GeV$^{2}$ using precise new $g_{1}^{p}$ and $g_{1}^{d}$ data taken with the CLAS detector at Jefferson Lab. A higher-twist analysis of the $Q^{2}$-dependence of the Bjorken Sum yields the twist-4 coefficient $f_{2}^{p-n}=-0.064 \pm0.009\pm_{0.036}^{0.032}$. This leads to the color polarizabilities $\chi_{E}^{p-n}=-0.032\pm0.024$ and $\chi_{B}^{p-n}=0.032\pm0.013$. The strong force coupling is determined to be \alpha_{s}^{\overline{\mbox{ MS}}}(M_{Z}^{2})=0.1124\pm0.0061, which has an uncertainty a factor of 1.5 smaller than earlier estimates using polarized DIS data. This improvement makes the comparison between $\alpha_{s}$ extracted from polarized DIS and other techniques a valuable test of QCD.Comment: Published in Phys. Rev. D. V1: 8 pages, 3 figures. V2: Updated references; Included threshold matching in \alpha_s evolution. Corrected a typo on the uncertainty for \Lambda_QCD. V3: Published versio

Status of Longitudinal Polarized Parton Densities and Higher Twist

The present status of the longitudinal polarized parton densities (PDFs) and the contribution of their first moments to the nucleon spin is discussed. Special attention is paid to the role of higher twist effects in determining the PDFs and to the polarized strange quark and gluon densities, which are still not well determined from the present data.Comment: 6 pages, 5 figures; to appear in the proceedings of the 18th International Symposium on Spin Physics (SPIN20008), October 6 - 11, 2008, Charlottesville, Virginia, US

How does age-related macular degeneration affect real-world visual ability and quality of life? A systematic review

Objectives To review systematically the evidence of age-related macular degeneration (AMD) affecting real-world visual ability and quality of life (QoL). To explore trends in specific topics within this body of the literature. Design Systematic review. Methods A systematic literature search was carried out using MEDLINE, EMBASE, CINAHL, PsycINFO, PsychARTICLES and Health and Psychosocial Instruments for articles published up to January 2015 for studies including people diagnosed with AMD, assessing real-world visual ability or QoL as an outcome. Two researchers screened studies for eligibility. Details of eligible studies including study design, characteristics of study population and outcomes measured were recorded in a data extraction table. All included studies underwent quality appraisal using the Mixed Methods Appraisal Tool 2011 Version (MMAT). Results From 5284 studies, 123 were eligible for inclusion. A range of approaches were identified, including performance-based methods, quantitative and qualitative patient-reported outcome measures (PROMs). AMD negatively affects tasks including mobility, face recognition, perception of scenes, computer use, meal preparation, shopping, cleaning, watching TV, reading, driving and, in some cases, self-care. There is evidence for higher rates of depression among people with AMD than among community dwelling elderly. A number of adaptation strategies have been associated with AMD of varying duration. Much of the research fails to report the type of AMD studied (59% of included studies) or the duration of disease in participants (74%). Of those that do report type studied, the breakdown is as follows: wet AMD 20%, dry AMD 4% and both types 17%. Conclusions There are many publications highlighting the negative effects of AMD in various domains of life. Future research should focus on delivering some of this research knowledge into patient management and clinical trials and differentiating between the types of AMD

Are Current Methods of Measuring Dark Adaptation Effective in Detecting the Onset and Progression of Age-Related Macular Degeneration? A Systematic Literature Review

Introduction Dark adaptation (DA) has been proposed as a possible functional biomarker for age-related macular degeneration (AMD). In this systematic review we aim to evaluate current methodology used to assess DA in people with AMD, the evidence of precision in detecting the onset and progression of AMD, and the relationship between DA and other functional and structural measures. Methods MEDLINE, EMBASE, CINAHL, AMED, PsycINFO, PsycARTICLES were searched for studies published between January 2006 and January 2020 that assessed DA in people with AMD. Details of eligible studies including study design, characteristics of study population and outcomes were recorded. All included studies underwent quality appraisal using approved critical appraisal tools. This systematic review follows PRISMA guidelines (PROSPERO registration number: CRD42019129486). Results Forty-eight studies were eligible for inclusion, reporting a variety of instruments and protocols to assess different DA parameters. Twenty of these studies used the AdaptDx (MacuLogix, Hummelstown, PA, USA) instrument and assessed rod-intercept time (RIT). Most of these reported that RIT was delayed in people with AMD and this delay worsened with AMD severity. Four studies, involving 533 participants, reported estimates of diagnostic performance of AdaptDx to separate people with AMD from visually healthy controls. DA has been compared to other measures of visual function, patient-reported outcome measures (PROMs) and structural measures. Ten studies specifically considered evidence that the presence of certain structural abnormalities was associated with impaired DA in AMD. Conclusions This systematic review indicates overwhelming evidence of reasonable quality for an association between impaired DA and AMD. Data on the repeatability and reproducibility of DA measurement are sparse. There is evidence that structural abnormalities such as reticular drusen are associated with prolongation of DA time. Fewer studies have explored an association between DA and other measures of visual function or PROMs. We found no studies that had compared DA with performance-based measures

Updated Report Acceleration of Polarized Protons to 120-150 GeV/c at Fermilab

The SPIN@FERMI collaboration has updated its 1991-95 Reports on the acceleration of polarized protons in Fermilab's Main Injector, which was commissioned by Fermilab. This Updated Report summarizes some updated Physics Goals for a 120-150 GeV/c polarized proton beam. It also contains an updated discussion of the Modifications and Hardware needed for a polarized beam in the Main Injector, along with an updated Schedule and Budget.Comment: 30 pages, 12 figure

Experimental determination of the evolution of the Bjorken integral at low Q^2

We extract the Bjorken integral Gamma^{p-n}_1 in the range 0.17 < Q^2 < 1.10 GeV^2 from inclusive scattering of polarized electrons by polarized protons, deuterons and 3He, for the region in which the integral is dominated by nucleon resonances. These data bridge the domains of the hadronic and partonic descriptions of the nucleon. In combination with earlier measurements at higher Q^2, we extract the non-singlet twist-4 matrix element f_2.Comment: Quoted world data updated. Minor change in some results, Minor rephrasin