Psychosocial Development in Racially and Ethnically Diverse Youth: Conceptual and Methodological Challenges in the 21st Century

As the US population becomes more diverse in the 21st century, researchers face many conceptual and methodological challenges in working with diverse populations. We discuss these issues for racially and ethnically diverse youth, using Spencer’s phenomenological variant of ecological systems theory (PVEST) as a guiding framework. We present a brief historical background and discuss recurring conceptual flaws in research on diverse youth, presenting PVEST as a corrective to these flaws. We highlight the interaction of race, culture, socioeconomic status, and various contexts of development with identity formation and other salient developmental processes. Challenges in research design and interpretation of data are also covered with regard to both assessment of contexts and developmental processes. We draw upon examples from neighborhood assessments, ethnic identity development, and attachment research to illustrate conceptual and methodological challenges, and we discuss strategies to address these challenges. The policy implications of our analysis are also considered

Physical Conditions of Accreting Gas in T Tauri Star Systems

We present results from a low resolution (R~300) near-infrared spectroscopic variability survey of actively accreting T Tauri stars (TTS) in the Taurus-Auriga star forming region. Paschen and Brackett series H I recombination lines were detected in 73 spectra of 15 classical T Tauri systems. The values of the Pan/PaB, Brn/BrG, and BrG/Pan H I line ratios for all observations exhibit a scatter of < 20% about the weighted mean, not only from source to source, but also for epoch-to-epoch variations in the same source. A representative or `global' value was determined for each ratio in both the Paschen and Brackett series as well as the BrG/Pan line ratios. A comparison of observed line ratio values was made to those predicted by the temperature and electron density dependent models of Case B hydrogen recombination line theory. The measured line ratios are statistically well-fit by a tightly constrained range of temperatures (T < 2000 K) and electron densities 1e9 < n_e < 1e10 cm^-3. A comparison of the observed line ratio values to the values predicted by the optically thick and thin local thermodynamic equilibrium cases rules out these conditions for the emitting H I gas. Therefore, the emission is consistent with having an origin in a non-LTE recombining gas. While the range of electron densities is consistent with the gas densities predicted by existing magnetospheric accretion models, the temperature range constrained by the Case B comparison is considerably lower than that expected for accreting gas. The cooler gas temperatures will require a non-thermal excitation process (e.g., coronal/accretion-related X-rays and UV photons) to power the observed line emission.Comment: 12 pages, emulateapj format, Accepted for publication in Ap

On the massive star content of the nearby dwarf irregular Wolf-Rayet galaxy IC 4662

Aims. We investigate the massive stellar content of the nearby dwarf irregular Wolf-Rayet galaxy IC 4662, and consider its global star forming properties in the context of other metal-poor galaxies, the SMC, IC 10 and NGC 1569. Methods. Very Large Telescope/FORS2 imaging and spectroscopy plus archival Hubble Space Telescope/ACS imaging datasets permit us to spatially identify the location, number and probable subtypes of Wolf-Rayet stars within this galaxy. We also investigate suggestions that a significant fraction of the ionizing photons of the two giant H II regions A1 and A2 lie deeply embedded within these regions. Results. Wolf-Rayet stars are associated with a number of sources within IC 4662-A1 and A2, plus a third compact H II region to the north west of A1 (A1-NW). Several sources appear to be isolated, single (or binary) luminous nitrogen sequence WR stars, while extended sources are clusters whose masses exceed the Orion Nebula Cluster by, at most, a factor of two. IC 4662 lacks optically visible young massive, compact clusters that are common in other nearby dwarf irregular galaxies. A comparison between radio and H-derived ionizing fluxes of A1 and A2 suggests that 30–50% of their total Lyman continuum fluxes lie deeply embedded within these regions. Conclusions. The star formation surface density of IC 4662 is insufficient for this galaxy to qualify as a starburst galaxy, based upon its photometric radius, R25. If instead, we were to adopt the

Predictions for high-frequency radio surveys of extragalactic sources

We present detailed predictions of the contributions of the various source populations to the counts at frequencies of tens of GHz. New evolutionary models are worked out for flat-spectrum radio quasars, BL Lac objects, and steep-spectrum sources. Source populations characterized by spectra peaking at high radio frequencies, such as extreme GPS sources, ADAF/ADIOS sources and early phases of gamma-ray burst afterglows are also dealt with. The counts of different populations of star-forming galaxies (normal spirals, starbursts, high-z galaxies detected by SCUBA and MAMBO surveys, interpreted as proto-spheroidal galaxies) are estimated taking into account both synchrotron and free-free emission, and dust re-radiation. Our analysis is completed by updated counts of Sunyaev-Zeldovich effects in clusters of galaxies and by a preliminary estimate of galactic-scale Sunyaev-Zeldovich signals associated to proto-galactic plasma.Comment: 12 pages, 14 figures, to be published in A&

Radio Studies of the Middle Corona: Current State and New Prospects in the Next Decade

The middle corona, defined as the region between ~1.5-6 solar radii, is a critical transition region that connects the highly structured lower corona to the outer corona where the magnetic field becomes predominantly radial. This paper discusses the current state of radio studies on the middle corona, challenges to obtaining a more comprehensive picture, and recommends an outlook

Changing Politics: Towards a New Democracy

In October 2014 the PSA joint-funded a Consultation event ‘Changing Politics – Towards a New Democracy’ with St. George’s House. The Chair of the PSA, Professor Matthew Flinders, chaired the event which brought together participants from a range of fields (including academics, think tankers and practitioners in several policy areas). Today, St. George’s House has published a report which highlights the main themes emerging from the discussion as well as some conclusions and recommendations. It identifies several areas where changes are urgently needed to reinvigorate democracy. The report concludes that to fully succeed in addressing the growth of political apathy and disengagement, parties and leaders must forget their differences and join citizens, academics, charities and others to address this problem with all available energy and resources

A Kinase-Independent Role for the Rad3ATR-Rad26ATRIP Complex in Recruitment of Tel1ATM to Telomeres in Fission Yeast

ATM and ATR are two redundant checkpoint kinases essential for the stable maintenance of telomeres in eukaryotes. Previous studies have established that MRN (Mre11-Rad50-Nbs1) and ATRIP (ATR Interacting Protein) interact with ATM and ATR, respectively, and recruit their partner kinases to sites of DNA damage. Here, we investigated how Tel1ATM and Rad3ATR recruitment to telomeres is regulated in fission yeast. Quantitative chromatin immunoprecipitation (ChIP) assays unexpectedly revealed that the MRN complex could also contribute to the recruitment of Tel1ATM to telomeres independently of the previously established Nbs1 C-terminal Tel1ATM interaction domain. Recruitment of Tel1ATM to telomeres in nbs1-c60Δ cells, which lack the C-terminal 60 amino acid Tel1ATM interaction domain of Nbs1, was dependent on Rad3ATR-Rad26ATRIP, but the kinase domain of Rad3ATR was dispensable. Thus, our results establish that the Rad3ATR-Rad26ATRIP complex contributes to the recruitment of Tel1ATM independently of Rad3ATR kinase activity, by a mechanism redundant with the Tel1ATM interaction domain of Nbs1. Furthermore, we found that the N-terminus of Nbs1 contributes to the recruitment of Rad3ATR-Rad26ATRIP to telomeres. In response to replication stress, mammalian ATR–ATRIP also contributes to ATM activation by a mechanism that is dependent on the MRN complex but independent of the C-terminal ATM interaction domain of Nbs1. Since telomere protection and DNA damage response mechanisms are very well conserved between fission yeast and mammalian cells, mammalian ATR–ATRIP may also contribute to the recruitment of ATM to telomeres and to sites of DNA damage independently of ATR kinase activity