A Gravitational Redshift Determination of the Mean Mass of White Dwarfs. DBA and DB Stars

We measure apparent velocities (v_app) of absorption lines for 36 white dwarfs (WDs) with helium-dominated atmospheres -- 16 DBAs and 20 DBs -- using optical spectra taken for the European Southern Observatory SN Ia progenitor survey (SPY). We find a difference of 6.9+/-6.9 km/s in the average apparent velocity of the H-alpha lines versus that of the HeI 5876AA for our DBAs. This is a measure of the blueshift of this He line due to pressure effects. By using this as a correction, we extend the gravitational redshift method employed by Falcon et al. (2010) to use the apparent velocity of the HeI 5876AA line and conduct the first gravitational redshift investigation of a group of WDs without visible hydrogen lines. We use biweight estimators to find an average apparent velocity, _BI, (and hence average gravitational redshift, _BI) for our WDs; from that we derive an average mass, _BI. For the DBAs, we find _BI = 40.8+/-4.7 km/s and derive _BI = 0.71 +0.04 -0.05 Msun. Though different from of DAs (32.57 km/s) at the 91% confidence level and suggestive of a larger DBA mean mass than that for normal DAs derived using the same method (0.647 +0.013 -0.014 Msun; Falcon et al. 2010), we do not claim this as a stringent detection. Rather, we emphasize that the difference between _BI of the DBAs and of normal DAs is no larger than 9.2 km/s, at the 95% confidence level; this corresponds to roughly 0.10 Msun. For the DBs, we find ^He_BI = 42.9+/-8.49 km/s after applying the blueshift correction and determine _BI = 0.74 +0.08 -0.09 Msun. The difference between ^He_BI of the DBs and of DAs is less than or equal to 11.5 km/s (~0.12 Msun), at the 95% confidence level. The gravitational redshift method indicates much larger mean masses than the spectroscopic determinations of the same sample by Voss et al. (2007)...Comment: Accepted to the Astrophysical Journal, 10 pages double-column, 3 figures, 5 table

Advanced single permanent magnet axipolar ironless stator ac motor for electric passenger vehicles

A program was conducted to design and develop an advanced-concept motor specifically created for propulsion of electric vehicles with increased range, reduced energy consumption, and reduced life-cycle costs in comparison with conventional systems. The motor developed is a brushless, dc, rare-earth cobalt, permanent magnet, axial air gap inductor machine that uses an ironless stator. Air cooling is inherent provided by the centrifugal-fan action of the rotor poles. An extensive design phase was conducted, which included analysis of the system performance versus the SAE J227a(D) driving cycle. A proof-of-principle model was developed and tested, and a functional model was developed and tested. Full generator-level testing was conducted on the functional model, recording electromagnetic, thermal, aerodynamic, and acoustic noise data. The machine demonstrated 20.3 kW output at 1466 rad/s and 160 dc. The novel ironless stator demonstated the capability to continuously operate at peak current. The projected system performance based on the use of a transistor inverter is 23.6 kW output power at 1466 rad/s and 83.3 percent efficiency. Design areas of concern regarding electric vehicle applications include the inherently high windage loss and rotor inertia

New results on GP Com

We present high resolution optical and UV spectra of the 46 min orbital period, helium binary, GP Com. Our data contains simultaneous photometric correction which confirms the flaring behaviour observed in previous optical and UV data. In this system all lines show a triple peaked structure where the outer two peaks are associated with the accretion disc around the compact object. The main aim of this paper is to constrain the origin of the central peak, also called ``central spike''. We find that the central spike contributes to the flare spectra indicating that its origin is probably the compact object. We also detect that the central spike moves with orbital phase following an S-wave pattern. The radial velocity semiamplitude of the S-wave is ~10 km/s indicating that its origin is near the centre of mass of the system, which in this case lies very close to the white dwarf. Our resolution is higher than that of previous data which allows us to resolve structure in the central peak of the line. The central spike in three of the HeI lines shows another peak blueshifted with respect to the main peak. We propose that one of the peaks is a neutral helium forbidden transition excited in a high electron density region. This forbidden transition is associated with the permitted one (the stronger peak in two of the lines). The presence of a high electron density region again favours the white dwarf as their origin.Comment: 14 pages, 16 figures. Accepted for publication in A&

Guiding principles for evaluating the impacts of conservation interventions on human well-being

Measures of socio-economic impacts of conservation interventions have largely been restricted to externally defined indicators focused on income, which do not reflect people's priorities. Using a holistic, locally grounded conceptualization of human well-being instead provides a way to understand the multi-faceted impacts of conservation on aspects of people's lives that they value. Conservationists are engaging with well-being for both pragmatic and ethical reasons, yet current guidance on how to operationalize the concept is limited. We present nine guiding principles based around a well-being framework incorporating material, relational and subjective components, and focused on gaining knowledge needed for decision-making. The principles relate to four key components of an impact evaluation: (i) defining well-being indicators, giving primacy to the perceptions of those most impacted by interventions through qualitative research, and considering subjective well-being, which can affect engagement with conservation; (ii) attributing impacts to interventions through quasi-experimental designs, or alternative methods such as theory-based, case study and participatory approaches, depending on the setting and evidence required; (iii) understanding the processes of change including evidence of causal linkages, and consideration of trajectories of change and institutional processes; and (iv) data collection with methods selected and applied with sensitivity to research context, consideration of heterogeneity of impacts along relevant societal divisions, and conducted by evaluators with local expertise and independence from the intervention

Resilience to climate shocks in the tropics

This focus collection on resilience to climate shocks in the tropics draws together 16 papers that predominantly examine the impacts of, and responses to, the 2015/2016 El Niño-Southern Oscillation event, in a range of contexts. This introductory synthesis contextualises the collection of papers by reviewing important concepts and highlighting some important insights that emerge from the collection. The papers in this collection collectively highlight: the value of longitudinal and interdisciplinary research in understanding both the roots of, and responses to, resilience challenges; the critical interaction between climatic and land-use changes; and the ways in which governance arrangements underpin societal decision-making across a range of scales and contexts to shape resilience

Individual freedom versus collective responsibility: an ethicist's perspective

Philosophical theories of collective action have produced a number of alternative accounts of the rationality and morality of self-interest and altruism. These have obvious applications to communicable disease control, the avoidance of antibiotic resistance, the responsibility of healthcare professionals to patients with serious communicable diseases, and the sharing of personal data in epidemiological research

Summer Habitat Use of Littoral-Zone Fishes in Lake Tahoe and the Effects of Shoreline Structures

We used scuba observations to determine summer habitat use and the effects of piers on the littoral-zone fish community in Lake Tahoe, California–Nevada. Habitat complexity declined with depth. Over 50% of the littoral zone less than 2 m deep was composed of complex boulder substrates, but this substrate represented less than 10% of the habitat between 10 and 18 m deep. A severe drought lowered the surface elevation of the lake 2 m and reduced the wetted complex rocky habitat by 20% between the 0- and l0-m isobaths (referenced to the mean lake level of 1,899 m above sea level). The dominant littoral-zone fish, adult Lahontan redsides Richardsonius egregius, were found at depths ranging from 1–10 m over substrates, but at somewhat greater depths (3–10 m) over cobble–boulder substrates. Juvenile Lahontan redsides were concentrated around boulders at depths of 1–3 m, and their densities were much lower than the densities of adults. Adult tui chub Gila bicolor and rainbow trout Oncorhynchus mykiss were also most often associated with complex boulder habitats. The daytime densities and species composition of fishes associated with piling-supported piers did not differ significantly from adjacent no-pier areas, whereas the densities of Lahontan redsides, tui chubs, Lahontan speckled dace Rhynichthys osculus robustus, and Tahoe suckers Catostomus tahoensis associated with the complex structure of rock-crib piers were significantly higher than in adjacent no-crib areas. Fish density increased 5–12-fold at night relative to the observed daytime densities in the pier, rock-crib, no-pier, and no-crib transects

The Application of Transformational Leadership Theory to Parenting: Questionnaire Development and Implications for Adolescent Self-Regulatory Efficacy and Life Satisfaction

We draw upon transformational leadership theory to develop an instrument to measure transformational parenting for use with adolescents. First, potential items were generated that were developmentally appropriate and evidence for content validity was provided through the use of focus groups with parents and adolescents. We subsequently provide evidence for several aspects of construct validity of measures derived from the Transformational Parenting Questionnaire (TPQ). Data were collected from 857 adolescents (Mage = 14.70 years), who rated the behaviors of their mothers and fathers. The results provided support for a second-order measurement model of transformational parenting. In addition, positive relationships between mothers’ and fathers’ transformational parenting behaviors, adolescents’ self-regulatory efficacy for physical activity and healthy eating, and life satisfaction were found. The results of this research support the application of transformational leadership theory to parenting behaviors, as well as the construct validity of measures derived from the TPQ. (AUTHORS' ABSTRACT