Field-induced local moments around nonmagnetic impurities in metallic cuprates

We consider a defect in a strongly correlated host metal and discuss, within a slave boson mean field formalism for the $t-t'-J$ model, the formation of an induced paramagnetic moment which is extended over nearby sites. We study in particular an impurity in a metallic band, suitable for modelling the optimally doped cuprates, in a regime where the impurity moment is paramagnetic. The form of the local susceptibility as a function of temperature and doping is found to agree well with recent NMR experiments, without including screening processes leading to the Kondo effect.Comment: 7 pages, submitted to Phys Rev

Bilingualism alters children’s frontal lobe functioning for attentional control

Bilingualism is a typical linguistic experience, yet relatively little is known about its impact on children’s cognitive and brain development. Theories of bilingualism suggest that early dualâ language acquisition can improve children’s cognitive abilities, specifically those relying on frontal lobe functioning. While behavioral findings present much conflicting evidence, little is known about its effects on children’s frontal lobe development. Using functional nearâ infrared spectroscopy (fNIRS), the findings suggest that Spanishâ English bilingual children (n = 13, ages 7â 13) had greater activation in left prefrontal cortex during a nonâ verbal attentional control task relative to ageâ matched English monolinguals. In contrast, monolinguals (n = 14) showed greater right prefrontal activation than bilinguals. The present findings suggest that early bilingualism yields significant changes to the functional organization of children’s prefrontal cortex for attentional control and carry implications for understanding how early life experiences impact cognition and brain development.This fNIRS study investigated the impact of bilingual exposure on children’s brain organization for attentional control (N = 27, ages 7â 13). During a nonâ verbal attention task, bilinguals showed greater left frontal lobe activation than monolinguals. Monolinguals showed greater right frontal lobe activation than bilinguals. The findings suggest that bilingualism affects the functionality of children’s left prefrontal cortex for attentional control.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/1/desc12377-sup-0001-FigS1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/2/desc12377.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/3/desc12377_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/4/desc12377-sup-0003-SupInfo.pd

Achromatizing a liquid-crystal spectropolarimeter: Retardance vs Stokes-based calibration of HiVIS

Astronomical spectropolarimeters can be subject to many sources of systematic error which limit the precision and accuracy of the instrument. We present a calibration method for observing high-resolution polarized spectra using chromatic liquid-crystal variable retarders (LCVRs). These LCVRs allow for polarimetric modulation of the incident light without any moving optics at frequencies >10Hz. We demonstrate a calibration method using pure Stokes input states that enables an achromatization of the system. This Stokes-based deprojection method reproduces input polarization even though highly chromatic instrument effects exist. This process is first demonstrated in a laboratory spectropolarimeter where we characterize the LCVRs and show example deprojections. The process is then implemented the a newly upgraded HiVIS spectropolarimeter on the 3.67m AEOS telescope. The HiVIS spectropolarimeter has also been expanded to include broad-band full-Stokes spectropolarimetry using achromatic wave-plates in addition to the tunable full-Stokes polarimetric mode using LCVRs. These two new polarimetric modes in combination with a new polarimetric calibration unit provide a much more sensitive polarimetric package with greatly reduced systematic error.Comment: Accepted in PAS

Critical evaluation of magnetic field detections reported for pulsating B-type stars in the light of ESPaDOnS, Narval and reanalyzed FORS1/2 observations

Recent spectropolarimetric studies of 7 SPB and $\beta$ Cep stars have suggested that photospheric magnetic fields are more common in B-type pulsators than in the general population of B stars, suggesting a significant connection between magnetic and pulsational phenomena. We present an analysis of new and previously published spectropolarimetric observations of these stars. New Stokes $V$ observations obtained with the high-resolution ESPaDOnS and Narval instruments confirm the presence of a magnetic field in one of the stars ($\epsilon$ Lup), but find no evidence of magnetism in 5 others. A re-analysis of the published longitudinal field measurements obtained with the low-resolution FORS1/2 spectropolarimeters finds that the measurements of all stars show more scatter from zero than can be attributed to Gaussian noise, suggesting the presence of a signal and/or systematic under-estimation of error bars. Re-reduction and re-measurement of the FORS1/2 spectra from the ESO archive demonstrates that small changes in reduction procedure lead to substantial changes in the inferred longitudinal field, and substantially reduces the number of field detections at the 3$\sigma$ level. Furthermore, we find that the published periods are not unique solutions to the time series of either the original or the revised FORS1/2 data. We conclude that the reported field detections, proposed periods and field geometry models for $\alpha$ Pyx, 15 CMa, 33 Eri and V1449 Aql are artefacts of the data analysis and reduction procedures, and that magnetic fields at the reported strength are no more common in SPB/$\beta$ Cep stars than in the general population of B stars.Comment: 10 pages, 5 figures, accepted for publication in ApJ, 2012, typo correcte

Vulnerability to bullying in children with a history of specific speech and language difficulties

This is an electronic version of an article published in Lindsay, Geoff and Dockrell, Julie and Mackie, Clare (2008) Vulnerability to bullying in children with a history of specific speech and language difficulties. European Journal of Special Needs Education, 23 (1). pp. 1-16. European Journal of Special Needs Education is available online at: http://www.informaworld.com/10.1080/0885625070179120

Financial capability and functional financial literacy in young adults with developmental language disorder

Background: Financial capability is an essential feature of the organisation of one’s personal life and engagement with society. Very little is known of how adequately individuals with developmental language disorder (DLD) handle financial matters. It is known that language difficulties place them at a disadvantage in many aspects of their development and during their transition into adulthood, leading to the possibility that financial issues may prove burdensome for them. This study examines the financial capability and functional financial literacy of young adults with DLD and compares them to those of age matched peers (AMPs). We tested the expectation that those with DLD would find financial management more challenging than would their peers, and that they would need to seek greater support from family members or other people. Methods: Participants completed a detailed individual interview, which included items drawn from the British Household Panel Survey and additional measures of financial capability, functional financial literacy and of perceived support. Nonverbal IQ, language, reading and numeracy measures were also collected. Results: Compared to typically developing AMPs, young people with DLD report less extensive engagement with financial products and lower competence in functional financial literacy. A considerably higher proportion of those with DLD (48% vs 16% of AMPs) report that they draw on support, primarily from parents, in various financial tasks, including paying bills, choosing financial products, and taking loans from family or friends. Conclusions: This is the first study to consider the financial capability skills and functional financial literacy of young adults with DLD. We provide novel evidence that some young adults with DLD lack functional financial skills and require support to successfully manage their finances. This has policy implications that relate not only to engaging affected individuals in discussions about financial management but also to wider familial support

Magnetic fields and differential rotation on the pre-main sequence I: The early-G star HD 141943 - brightness and magnetic topologies

Spectroscopic and spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at four observing epochs (in 2006, 2007, 2009 and 2010). The observations were undertaken at the 3.9-m Anglo-Australian Telescope using the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. Brightness and surface magnetic field topologies were reconstructed for the star using the technique of least-squares deconvolution to increase the signal-to-noise of the data. The reconstructed brightness maps show that HD 141943 had a weak polar spot and a significant amount of low latitude features, with little change in the latitude distribution of the spots over the 4 years of observations. The surface magnetic field was reconstructed at three of the epochs from a high order (l <= 30) spherical harmonic expansion of the spectropolarimetric observations. The reconstructed magnetic topologies show that in 2007 and 2010 the surface magnetic field was reasonably balanced between poloidal and toroidal components. However we find tentative evidence of a change in the poloidal/toroidal ratio in 2009 with the poloidal component becoming more dominant. At all epochs the radial magnetic field is predominantly non-axisymmetric while the azimuthal field is predominantly axisymmetric with a ring of positive azimuthal field around the pole similar to that seen on other active stars.Comment: 18 pages, 17 figures, accepted by MNRA

Narrative skills in adolescents with a history of SLI in relation to non-verbal IQ scores

There is a debate about whether the language of children with primary language disorders and normal cognitive levels is qualitatively different from those with language impairments who have low or borderline non-verbal IQ (NVIQ). As children reach adolescence, this distinction may be even harder to ascertain, especially in naturalistic settings. Narrative may provide a useful, ecologically valid way in which to assess the language ability of adolescents with specific language impairment (SLI) who have intact or lowered NVIQ and to determine whether there is any discernable difference in every day language. Nineteen adolescents with a history of SLI completed two narrative tasks: a story telling condition and a conversational condition. Just under half the group (n = 8) had non-verbal IQs of 85. The remaining 11 had NVIQs in the normal range or above. Four areas of narrative (productivity, syntax, cohesion and performance) were assessed. There were no differences between the groups on standardized tests of language. However, the group with low NVIQ were poorer on most aspects of narrative, suggesting that cognitive level is important, even when language is the primary disorder. The groups showed similar patterns of differences between story telling and conversational narrative. It was concluded that adolescents with a history of SLI and poor cognitive levels have poorer narrative skills than those with normal range NVIQ even though these may not be detected by standardized assessment. Their difficulties present as qualitatively similar to those with normal range NVIQ and narratives appear impoverished rather than inaccurate

The first magnetic maps of a pre-main sequence binary star system - HD 155555

We present the first maps of the surface magnetic fields of a pre-main sequence binary system. Spectropolarimetric observations of the young, 18 Myr, HD 155555 (V824 Ara, G5IV + K0IV) system were obtained at the Anglo-Australian Telescope in 2004 and 2007. Both datasets are analysed using a new binary Zeeman Doppler imaging (ZDI) code. This allows us to simultaneously model the contribution of each component to the observed circularly polarised spectra. Stellar brightness maps are also produced for HD 155555 and compared to previous Doppler images. Our radial magnetic maps reveal a complex surface magnetic topology with mixed polarities at all latitudes. We find rings of azimuthal field on both stars, most of which are found to be non-axisymmetric with the stellar rotational axis. We also examine the field strength and the relative fraction of magnetic energy stored in the radial and azimuthal field components at both epochs. A marked weakening of the field strength of the secondary star is observed between the 2004 and 2007 epochs. This is accompanied by an apparent shift in the location of magnetic energy from the azimuthal to radial field. We suggest that this could be indicative of a magnetic activity cycle. We use the radial magnetic maps to extrapolate the coronal field (by assuming a potential field) for each star individually - at present ignoring any possible interaction. The secondary star is found to exhibit an extreme tilt (~75 deg) of its large scale magnetic field to that of its rotation axis for both epochs. The field complexity that is apparent in the surface maps persists out to a significant fraction of the binary separation. Any interaction between the fields of the two stars is therefore likely to be complex also. Modelling this would require a full binary field extrapolation.Comment: 17 pages, 12 figures, accepted for publication in MNRA

Improving storytelling and vocabulary in secondary school students with language disorder: a randomized controlled trial

Background: Although language and communication difficulties are common in secondary school students, there has been limited research into the efficacy of interventions for adolescents with language and communication difficulties. Aims: To investigate the efficacy of teaching assistant (TA)-delivered narrative and vocabulary interventions to mainstream secondary school-aged students with language disorder. Methods & Procedures: A randomized controlled trial (RCT) of a language and communication intervention was used to evaluate the efficacy of vocabulary and narrative interventions to improve the vocabulary and narrative performance of adolescents (mean age = 12.8 years) with language disorder. The language and communication programmes (narrative, vocabulary and combined narrative and vocabulary) were delivered by TAs in the classroom, three times per week, for 45–60 min each, over 6 weeks, totalling 18 sessions. Standardized and intervention-specific measures were used as outcomes. Outcomes & Results: Twenty-one schools with 358 eligible participants were recruited. The three intervention groups showed significant improvements (d =.296) on a narrative latent variable defined by a standardized narrative assessment (the Expression, Reception and Recall of Narrative Instrument—ERRNI), but there were no significant improvements on an overall vocabulary latent variable compared with the waiting control group. Differential effects were found on some non-standardized intervention-specific measures with the narrative group making significantly more progress on narrative tasks compared with the waiting control group, the vocabulary group showing the same pattern on specific vocabulary tasks, and the combined narrative and vocabulary group making significantly more progress on some of the intervention-specific narrative, and all the intervention-specific vocabulary outcomes compared with the waiting control group. Conclusions & Implications: It is possible to improve narrative but not vocabulary skills, as assessed by standardized measures, in secondary school students with a relatively brief group TA-delivered intervention. There were differential effects for both narrative and vocabulary with intervention-specific measures. Future work is required to explore whether more intensive and longer lasting interventions would be more effective and to identify which students in this age group are most likely to benefit from such interventions