P* Index of Segregation: Distribution Under Reassignment

Students of intergroup relations have measured segregation with a P* index. In this article, we describe the distribution of this index under a stochastic model. We derive exact, closed-form expressions for the mean, variance, and skewness of P* under random segregation. These yield equivalent expressions for a second segregation index: η2. Our analytic results reveal some of the distributional properties of these indices, inform new standardizations of the indices, and enable small-sample significance testing. Two illustrative examples are presented

The Social and Cultural Context of Coping with Sickle Cell Disease: II. The Role of Financial Hardship in Adjustment to Sickle Cell Disease

Recent evidence on the negative psychological effects of poverty suggests that economic status alone might account for the adjustment problems attributed to sickle cell disease (SCD). The relationship of SCD and financial hardship to adjustment was examined in 327 ill children and their parents. SCD and hardship contributed independently to impaired child and parental functioning. For parents, illness severity had more negative effects than did financial hardship, but forPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66919/2/10.1177_0095798499025003003.pd

Conformational flexibility revealed by the crystal structure of a crenarchaeal RadA

Homologous recombinational repair is an essential mechanism for repair of double-strand breaks in DNA. Recombinases of the RecA-fold family play a crucial role in this process, forming filaments that utilize ATP to mediate their interactions with single- and double-stranded DNA. The recombinase molecules present in the archaea (RadA) and eukaryota (Rad51) are more closely related to each other than to their bacterial counterpart (RecA) and, as a result, RadA makes a suitable model for the eukaryotic system. The crystal structure of Sulfolobus solfataricus RadA has been solved to a resolution of 3.2 Å in the absence of nucleotide analogues or DNA, revealing a narrow filamentous assembly with three molecules per helical turn. As observed in other RecA-family recombinases, each RadA molecule in the filament is linked to its neighbour via interactions of a short β-strand with the neighbouring ATPase domain. However, despite apparent flexibility between domains, comparison with other structures indicates conservation of a number of key interactions that introduce rigidity to the system, allowing allosteric control of the filament by interaction with ATP. Additional analysis reveals that the interaction specificity of the five human Rad51 paralogues can be predicted using a simple model based on the RadA structure

SK2 channels are required for function and long-term survival of efferent synapses on mammalian outer hair cells

Cochlear hair cells use SK2 currents to shape responses to cholinergic efferent feedback from the brain. Using SK2-/- mice, we demonstrate that, in addition to their previously defined role in modulating hair cell membrane potentials, SK2 channels are necessary for long-term survival of olivocochlear fibers and synapses. Loss of the SK2 gene also results in loss of electrically driven olivocochlear effects in vivo, and down regulation of ryanodine receptors involved in calcium-induced calcium release, the main inducer of nAChR evoked SK2 activity. Generation of double-null mice lacking both the α10 nAChR gene, loss of which results in hypertrophied olivocochlear terminals, and the SK2 gene, recapitulates the SK2-/- synaptic phenotype and gene expression, and also leads to down regulation of α9 nAChR gene expression. The data suggest a hierarchy of activity necessary to maintain early olivocochlear synapses at their targets, with SK2 serving an epistatic, upstream, role to the nAChRs.Fil: Murthy, Vidya. Tufts University; Estados UnidosFil: Maison, Stéphane F.. Massachusetts Eye and Ear Infirmary; Estados Unidos. Harvard Medical School; Estados UnidosFil: Taranda, Julian. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Tufts University; Estados UnidosFil: Haque, Nadeem. University of Notre Dame; Estados UnidosFil: Bond, Chris T.. Oregon Health Sciences University; Estados UnidosFil: Elgoyhen, Ana Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Adelman, John P.. Oregon Health Sciences University; Estados UnidosFil: Liberman, M. Charles. Massachusetts Eye and Ear Infirmary; Estados Unidos. Harvard Medical School; Estados UnidosFil: Vetter, Douglas E.. Tufts University; Estados Unido

Submission of structural biology data for review purposes.

The editors discuss the submission of structural biology data

Comparing ST-segment elevation myocardial infarction care between patients residing in central and remote locations: a retrospective case series.

People who experience an ST-elevation myocardial infarction (STEMI) due to an occluded coronary artery require prompt treatment. Treatments to open a blocked artery are called reperfusion therapies (RTs), and can include intravenous pharmacological thrombolysis (TL) or primary percutaneous coronary intervention (pPCI) in a cardiac catheterisation laboratory (cath lab). Optimal RT (ORT) with pPCI or TL reduces morbidity and mortality. In remote areas, a number of geographical and organisational barriers may influence access to ORT. These are not well understood, and the exact proportion of patients who receive ORT - and the relationship to time of day and remoteness from the cardiac cath lab - is unknown. The aim of this retrospective study was to compare the characteristics of ORT delivery in central and remote locations in the north of Scotland, and to identify potential barriers to optimal care with a view to service redesign. The study was set in the north of Scotland. All patients who attended hospital with a STEMI between March 2014 and April 2015 were identified from national coding data. A data collection form was developed by the research team in several iterative stages. Clinical details were collected retrospectively from patients' discharge letters. Data included treatment location, date of admission, distance of patient from the cath lab, route of access to health care, left ventricular function and RT received. Distance of patients from the cath lab was described as remote if they were more than ninety minutes of driving time from the cardiac cath lab, and described as central if they were ninety minutes or less of driving time from the regional centre. For patients who made contact in a pre-hospital setting, ORT was defined as pre-hospital TL (PHT) or pPCI. For patients who self-presented to the hospital first, ORT was defined as in-hospital TL or pPCI. Data were described as mean (standard deviation) as appropriate. Chi-squared and student's t-test were used as appropriate. Each case was reviewed to determine if ORT was received; if ORT was not received, the reasons for this were recorded to identify potentially modifiable barriers. Of the 627 acute myocardial infarction patients initially identified, 131 had a STEMI, and the others were non-STEMI. From this STEMI cohort, 82 (62%) patients were classed as central and 49 (38%) were remote. In terms of initial therapy, 26 (20%) received pPCI, 19 (15%) received PHTs, 52 (40%) received in-hospital TL, while 33 (25%) received no initial RT. ORT was received by 53 (65%) central and 20 (41%) remote patients; chi-squared = 7.05, degrees of freedom = 130, p < 0.01).Several recurring barriers were identified. This study has therefore demonstrated a significant health inequality between the treatment of STEMI in remote locations compared to central locations. Potential barriers identified include staffing availability and training, public awareness and inter-hospital communication. This suggests that there remain significant opportunities to improve STEMI care for people living in the north of Scotland

The Social and Cultural Context of Coping with Sickle Cell Disease: III. Stress, Coping Tasks, Family Functioning, and Children’s Adjustment

Conceptions of individual and family coping with sickle cell disease (SCD) must incorporate several disease and sociocultural factors. This article proposes an integrative model and tests the relative contribution of model parameters to the prediction of social, academic, and psychological adjustment of children with SCD. The individual coping and family functioning variables most highly predictive of the child’s psychological outcomes (anxiety, depression, and positive mood) include parental psychological functioning, maturity demands made of the ill child, and the quality of relations with parents and siblings. Academic adjustment was significantly predicted by parental academic expectations and by the child’s rejection of a restrictive sick role. Competent social functioning also was predicted by the extent to which the ill child rejected the role of being sick.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67288/2/10.1177_0095798499025003006.pd

Confirmation of SBS 1150+599A As An Extremely Metal-Poor Planetary Nebula

SBS 1150+599A is a blue stellar object at high galactic latitude discovered in the Second Byurakan Survey. New high-resolution images of SBS 1150+599A are presented, demonstrating that it is very likely to be an old planetary nebula in the galactic halo, as suggested by Tovmassian et al (2001). An H-alpha image taken with the WIYN 3.5-m telescope and its "tip/tilt" module reveals the diameter of the nebula to be 9.2", comparable to that estimated from spectra by Tovmassian et al. Lower limits to the central star temperature were derived using the Zanstra hydrogen and helium methods to determine that the star's effective temperature must be > 68,000K and that the nebula is optically thin. New spectra from the MMT and FLWO telescopes are presented, revealing the presence of strong [Ne V] lambda 3425, indicating that the central star temperature must be > 100,000K. With the revised diameter, new central star temperature, and an improved central star luminosity, we can constrain photoionization models for the nebula significantly better than before. Because the emission-line data set is sparse, the models are still not conclusive. Nevertheless, we confirm that this nebula is an extremely metal-poor planetary nebula, having a value for O/H that is less than 1/100 solar, and possibly as low as 1/500 solar.Comment: 19 pages, 6 figures. Accepted for publication in the Astronomical Journa

Magnetic confinement of an electric arc in transverse supersonic flow

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77344/1/AIAA-2803-657.pd