Specific Isotopic Labeling and Photooxidation-linked Structural Changes in the Manganese-stabilizing Subunit of Photosystem II

Photosystem II (PSII) oxidizes water to molecular oxygen; the catalytic site is a cluster of four manganese ions. The catalytic site undergoes four sequential light-driven oxidation steps to form oxygen; these sequentially oxidized states are referred to as the Sn states, where n refers to the number of oxidizing equivalents stored. The extrinsic manganese stabilizing protein (MSP) of PSII influences the efficiency and stability of the manganese cluster, as well as the rates of the S state transitions. To understand how MSP influences photosynthetic water oxidation, we have employed isotope editing and difference Fourier transform infrared spectroscopy. MSP was expressed in Escherichia coli under conditions in which MSP aspartic and glutamic acid residues label at yields of 65 and 41%, respectively. Asparagine and glutamine were also labeled by this approach. GC/MS analysis was consistent with minimal scrambling of label into other amino acid residues and with no significant scrambling into the peptide bond. Selectively labeled MSP was then reconstituted to PSII, which had been stripped of native MSP. Difference Fourier transform infrared spectroscopy was used to probe the S 1QA to S2QA- transition at 200 K, as well as the S1QB to S2Q B- transition at 277 K. These experiments show that aspargine, glutamine, and glutamate residues in MSP are perturbed by photooxidation of manganese during the S1 to S2 transition

Shared Neuroanatomical Substrates of Impaired Phonological Working Memory Across Reading Disability and Autism

Background Individuals with reading disability and individuals with autism spectrum disorder (ASD) are characterized, respectively, by their difficulties in reading and social communication, but both groups often have impaired phonological working memory (PWM). It is not known whether the impaired PWM reflects distinct or shared neuroanatomical abnormalities in these two diagnostic groups. Methods White-matter structural connectivity via diffusion weighted imaging was examined in 64 children, age 5 to 17 years, with reading disability, ASD, or typical development, who were matched on age, gender, intelligence, and diffusion data quality. Results Children with reading disability and children with ASD exhibited reduced PWM compared with children with typical development. The two diagnostic groups showed altered white matter microstructure in the temporoparietal portion of the left arcuate fasciculus and in the occipitotemporal portion of the right inferior longitudinal fasciculus (ILF), as indexed by reduced fractional anisotropy and increased radial diffusivity. Moreover, the structural integrity of the right ILF was positively correlated with PWM ability in the two diagnostic groups but not in the typically developing group. Conclusions These findings suggest that impaired PWM is transdiagnostically associated with shared neuroanatomical abnormalities in ASD and reading disability. Microstructural characteristics in left arcuate fasciculus and right ILF may play important roles in the development of PWM. The right ILF may support a compensatory mechanism for children with impaired PWM

Spectro-interferometric observations of classical nova V458 Vul 2007

We used the Palomar Testbed Interferometer (PTI) to resolve 2.2 $\mu$m emission from the classical nova V458 Vul 2007 over the course of several days following its discovery on 2007 August 8.54 UT. We also obtained K-band photometric data and spectra of the nova during the early days of the outburst. We also used photometric measurements from the AAVSO database. This is a unique data set offering a 3-technique approach: high-resolution imaging, spectroscopy and photometry. Our analysis shows that the nova ejecta can be modeled as an inclined disk at low inclination i.e. low ellipticity which is consistent with the nova being in the fireball phase at which the outflowing gas is optically thick, confirmed by the presence of strong P-Cygni Balmer lines in the spectra. The expansion velocity is $\approx$1700 $\rm km\ s^{-1}$, derived from the H$\alpha$ line. By combining the nova's angular expansion rate measured by PTI with the expansion rate measured from spectroscopy, the inferred distance to the nova is 9.9-11.4 kpc. We also used the K-band fluxes and the derived size of the emission to estimate the total mass ejected from the nova $\approx 4\times 10^{-4} M_{\odot}$. The quick transition of the nova from Fe II to He/N class makes V458 Vul 2007 a hybrid nova.Comment: 31 pages, 7 figures, accepted for publication in Ap

X-ray Properties of the First SZE-selected Galaxy Cluster Sample from the South Pole Telescope

We present results of X-ray observations of a sample of 15 clusters selected via their imprint on the cosmic microwave background (CMB) from the thermal Sunyaev-Zel'dovich (SZ) effect. These clusters are a subset of the first SZ-selected cluster catalog, obtained from observations of 178 deg^2 of sky surveyed by the South Pole Telescope. Using X-ray observations with Chandra and XMM-Newton, we estimate the temperature, T_X, and mass, M_g, of the intracluster medium (ICM) within r_500 for each cluster. From these, we calculate Y_X=M_g T_X and estimate the total cluster mass using a M_500-Y_X scaling relation measured from previous X-ray studies. The integrated Comptonization, Y_SZ, is derived from the SZ measurements, using additional information from the X-ray measured gas density profiles and a universal temperature profile. We calculate scaling relations between the X-ray and SZ observables, and find results generally consistent with other measurements and the expectations from simple self-similar behavior. Specifically, we fit a Y_SZ-Y_X relation and find a normalization of 0.82 +- 0.07, marginally consistent with the predicted ratio of Y_SZ/Y_X=0.91+-0.01 that would be expected from the density and temperature models used in this work. Using the Y_X derived mass estimates, we fit a Y_SZ-M_500 relation and find a slope consistent with the self-similar expectation of Y_SZ ~ M^5/3 with a normalization consistent with predictions from other X-ray studies. We compare the X-ray mass estimates to previously published SZ mass estimates derived from cosmological simulations of the SPT survey. We find that the SZ mass estimates are lower by a factor of 0.89+-0.06, which is within the ~15% systematic uncertainty quoted for the simulation-based SZ masses.Comment: 28 pages, 19 figures, submitted to Ap

Altered engagement of the speech motor network is associated with reduced phonological working memory in autism

Nonword repetition, a common clinical measure of phonological working memory, involves component processes of speech perception, working memory, and speech production. Autistic children often show behavioral challenges in nonword repetition, as do many individuals with communication disorders. It is unknown which subprocesses of phonological working memory are vulnerable in autistic individuals, and whether the same brain processes underlie the transdiagnostic difficulty with nonword repetition. We used functional magnetic resonance imaging (fMRI) to investigate the brain bases for nonword repetition challenges in autism. We compared activation during nonword repetition in functional brain networks subserving speech perception, working memory, and speech production between neurotypical and autistic children. Autistic children performed worse than neurotypical children on nonword repetition and had reduced activation in response to increasing phonological working memory load in the supplementary motor area. Multivoxel pattern analysis within the speech production network classified shorter vs longer nonword-repetition trials less accurately for autistic than neurotypical children. These speech production motor-specific differences were not observed in a group of children with reading disability who had similarly reduced nonword repetition behavior. These findings suggest that atypical function in speech production brain regions may contribute to nonword repetition difficulties in autism.R01 DC011339 - NIDCD NIH HHS; R21 DC017576 - NIDCD NIH HHS; R03 DC014045 - NIDCD NIH HHS; T32 DC000038 - NIDCD NIH HHSPublished versio

Cosmological Constraints from Sunyaev-Zel'dovich-Selected Clusters with X-ray Observations in the First 178 Square Degrees of the South Pole Telescope Survey

We use measurements from the South Pole Telescope (SPT) Sunyaev Zel'dovich (SZ) cluster survey in combination with X-ray measurements to constrain cosmological parameters. We present a statistical method that fits for the scaling relations of the SZ and X-ray cluster observables with mass while jointly fitting for cosmology. The method is generalizable to multiple cluster observables, and self-consistently accounts for the effects of the cluster selection and uncertainties in cluster mass calibration on the derived cosmological constraints. We apply this method to a data set consisting of an SZ-selected catalog of 18 galaxy clusters at z > 0.3 from the first 178 deg2 of the 2500 deg2 SPT-SZ survey, with 14 clusters having X-ray observations from either Chandra or XMM. Assuming a spatially flat LCDM cosmological model, we find the SPT cluster sample constrain sigma_8 (Omega_m/0.25)^0.30 = 0.785 +- 0.037. In combination with measurements of the CMB power spectrum from the SPT and the seven-year WMAP data, the SPT cluster sample constrain sigma_8 = 0.795 +- 0.016 and Omega_m = 0.255 +- 0.016, a factor of 1.5 improvement on each parameter over the CMB data alone. We consider several extensions beyond the LCDM model by including the following as free parameters: the dark energy equation of state (w), the sum of the neutrino masses (sum mnu), the effective number of relativistic species (Neff), and a primordial non-Gaussianity (fNL). We find that adding the SPT cluster data significantly improves the constraints on w and sum mnu beyond those found when using measurements of the CMB, supernovae, baryon acoustic oscillations, and the Hubble constant. Considering each extension independently, we best constrain w=-0.973 +- 0.063 and the sum of neutrino masses sum mnu < 0.28 eV at 95% confidence, a factor of 1.25 and 1.4 improvement, respectively, over the constraints without clusters. [abbrev.]Comment: 21 pages, 8 figures, submitted to Ap

Large‐scale science education intervention research we can use

This article develops an argument that the type of intervention research most useful for improving science teaching and learning and leading to scalable interventions includes both research to develop and gather evidence of the efficacy of innovations and a different kind of research, design‐based implementation research (DBIR). DBIR in education focuses on what is required to bring interventions and knowledge about learning to all students, wherever they might engage in science learning. This research focuses on implementation, both in the development and initial testing of interventions and in the scaling up process. In contrast to traditional intervention research that focuses principally on one level of educational systems, DBIR designs and tests interventions that cross levels and settings of learning, with the aim of investigating and improving the effective implementation of interventions. The article concludes by outlining four areas of DBIR that may improve the likelihood that new standards for science education will achieve their intended purpose of establishing an effective, equitable, and coherent system of opportunities for science learning in the United States. © 2012 Wiley Periodicals, Inc. J Res Sci Teach 49: 281–304, 2012Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90232/1/21001_ftp.pd

Impact of Acculturation on Math Achievement in Community College Students

We investigated the potential moderating role of cultural adoption and cultural maintenance on the WM-math relation in a diverse group of CC students (n = 94). We expected that higher levels of adoption and maintenance would decrease WM load (via cognitive load) and aid math performance. At higher levels of acculturation, the WM-math relation was hypothesized approximate meta-analytic findings. Alternatively, at low levels of acculturation, the WM-math correlation was anticipated to be attenuated due to the added variability in culture and negative impact low acculturation levels have on WM, by increasing cognitive load. Within our sample (N = 94), WM-math correlations averaged r = .38 (similar to prior work), but acculturation did not significantly relate to math performance. Neither cultural adoption (computations: F=1.68, p =.199; word problems: F=.42, p =.521) nor cultural maintenance (computations: F=.83, p = .364; word problems: F=.36, p = .550) moderated the WM-math relations. In this context, developing individualized interventions would not appear to be an efficient use of resources. Instead, institutions (e.g., schools, city/federal government) may benefit from redoubling their efforts in providing academic and non-academic resources and supports to provide a more equitable educational experience to all students and offer the best possibility at future success. Post-hoc analyses, however, revealed that the cultural adoption-math relationship varied across different levels of vocabulary and math abilities, although not in the direction anticipated. Findings suggest complex relationships between WM, acculturation, and math such that acculturation does impact math performance when either vocabulary or math abilities are strong. This suggests additional individual and/or population characteristics should be explored more thoroughly (SES, discrimination, culture of origin) to further elucidate these complex relations

Executive Functioning in Struggling Readers: The NIH Examiner

Executive functioning (EF) is an important domain general control process implicated in the development of successful reading. While a number of previous studies have investigated the role of EF in children with reading difficulties (RD), results have been mixed due to lack of clarity within the domain and varied assessment methods. In the present study, we investigated the role of EF in a large group (n = 355) of 4th, 5th and 6th grade students with RD. To characterize EF, we utilized the NIH Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (NIH EXAMINER), a novel, short yet comprehensive, and free assessment. We investigated how the broad domain of EF is related to reading on three levels: word reading, reading fluency and reading comprehension, and for the latter, considered the impact of inference making. Results indicated relations of EF to reading consistent with prior work (average r = .26) with this novel measure. Multivariate multiple regression analyses compared the contribution of EF across all reading outcomes in a single model. Results revealed an overall effect of EF on reading, p < 0.001, and significant differences between fluency and comprehension, p < 0.001, and between decoding and comprehension, p = 0.014, but not between fluency and decoding, p = 0.062. The relation of EF to reading comprehension was fully mediated by inference making, and both indirect effects (short and long textual distance) were significant, although they were not significantly different from each other. Results may aid the development of specific reading interventions which consider the important and unique structure and role of EF in struggling readers.Psychology, Department o