A small molecule that induces assembly of a four way DNA junction at low temperature

Small molecules that induce the formation of higher order DNA structures have potential therapeutic and nanotechnology applications. Screening of a click library has identified the first compound to induce the formation of a Holliday junction structure at room temperature without the need for a high temperature annealing step

The Accreting White Dwarf in SS Cygni Revealed

We have carried out a combined Hubble Space Telescope (HST/GHRS) and Far Ultraviolet Spectroscopic Explorer FUSE) analysis of the prototype dwarf nova SS Cygni during quiescence. The FUSE and HST spectra were obtained at comparable times after outburst and have matching flux levels where the two spectra overlap. In our synthetic spectral analysis, we have used SS Cygni's accurate HST FGS parallax giving d = 166pc, a newly determined mass for the accreting white dwarf (Bitner et al. 2007) of Mwd=0.81Msun (lower than the previous, widely used 1.2 Msun) and the reddening E_{B-V} values 0.04 (Verbunt 1987; La Dous 1991) and 0.07 (Bruch and Engel 1994) derived from the 2175A absorption feature in the IUE LWP spectra. From the best-fit model solutions to the combined HST + FUSE spectral energy distribution, we find that the white dwarf is reaching a temperature Teff of 45-55,000K in quiescence, assuming Log(g)= 8.3 with a solar composition accreted atmosphere. The exact temperature of the WD depends on the reddening assumed and on the inclusion of a quiescent low mass accretion rate accretion disk. Accretion disk models alone fit badly in the FUSE range while, and if we take the distance to be a free parameter, the only accretion disk model which fits well is for a discordant distance of at least several hundred pc and an accretion rate (1.E-8 Msun/yr which is unacceptably high for a dwarf nova in quiescence. We discuss the implications of the white dwarf's temperature on the time-averaged accretion rate and long term compressional heating models.Comment: ApJ, accepte

Nuclear Fusion via Triple Collisions in Solar Plasma

We consider several nuclear fusion reactions that take place at the center of the sun, which are omitted in the standard pp-chain model. More specifically the reaction rates of the nonradiative production of ^3He, ^7Be, and ^8B nuclei in triple collisions involving electrons are estimated within the framework of the adiabatic approximation. These rates are compared with those of the corresponding binary fusion reactions.Comment: 3 pages, latex (RevTex), no figure

A risk assessment for the remote ocean: the case of the South East Atlantic

Degradation of the natural world and associated ecosystem services is attributed to a historical failure to include its ‘value’ in decision-making. Uncertainty in the quantification of the relationship between natural capital ‘assets’ that give rise to critical societal benefits and people is one reason for the omission of these values from natural resource management. As this uncertainty increases in marine systems and further still with distance from the coast, the connection between society and natural capital assets is less likely to be included adequately in decision-making. Natural capital assets of Areas Beyond National Jurisdiction (ABNJ), including those of the deep sea, are distant but are known to generate many benefits for society, from the diffuse and broad-scale benefits of climate regulation to the provision of wild fish for food. While our understanding of the precise relationships (the status of asset stocks, ecosystem functions and processes) that control the availability of ecosystem services and the flows of benefits is limited, this does not preclude opening a discourse on how these natural capital assets could best be managed to continue to benefit society. Here we apply a natural capital approach to the South East Atlantic ABNJ, one of the least scientifically understood regions of the planet, and develop a framework for risk assessment. We do this by describing the benefit flows from the natural capital assets of the region, appraising how activities are creating pressures on these flows and whether the controls for these pressures protect them. Our risk register highlights how governance currently favours the protection of direct (extractive) benefit flows from natural capital assets of the region, which are primarily targeted for financial benefit. Without a systems-based framework that can account for the cumulative pressures on natural capital assets their status, associated ecosystem services and benefits are at risk. Such an approach is essential to capture and protect the foundational and often diffuse connections between marine natural capital and global society.</jats:p

Validation of the Spanish Short Self-Regulation Questionnaire (SSSRQ) through Rasch Analysis

The Supplementary Material for this article can be found online at: http://journal.frontiersin.org/article/10.3389/fpsyg.2017.00276/full#supplementary-materialBackground: The aim of the study was to psychometrically characterize the Spanish Short Self-Regulation Questionnaire (SSSRQ) through Rasch analysis.Materials and Methods: 831 Spaniard university students (262 men), between 17 and 39 years of age and ranging from the first to the 5th year of studies, completed the SSSRQ questionnaire. Confirmatory factor analysis (CFA) was carried out in order to establish structural adequacy. Afterward, by means of the Rasch model, a study of each sub scale was conducted to test for dimensionality, fit of the sample questions, functionality of the response categories, reliability and estimation of Differential Item Functioning by gender and course.Results: The four sub-scales comply with the unidimensionality criteria, the questions are in line with the model, the response categories operate properly and the reliability of the sample is acceptable. Nonetheless, the test could benefit from the inclusion of additional items of both high and low difficulty in order to increase construct validity, discrimination and reliability for the respondents. Several items with differences in gender and course were also identified.Discussion: The results evidence the need and adequacy of this complementary psychometric analysis strategy, in relation to the CFA to enhance the instrument.This research was funded by Fundación Universitaria Konrad Lorenz (Colombia), by a R&D Project Grant, ref. EDU2011-24805 (2012-2015) of the Ministry of Science and Innovation (Spain), and with Federal Funds (European Union)

Mass Segregation in Globular Clusters

We present the results of a new study of mass segregation in two-component star clusters, based on a large number of numerical N-body simulations using our recently developed dynamical Monte Carlo code. Specifically, we follow the dynamical evolution of clusters containing stars with individual masses m_1 as well as a tracer population of objects with individual masses m_2=\mu m_1, using N=10^5 total stars. For heavy tracers, which could represent stellar remnants such as neutron stars or black holes in a globular cluster, we characterize in a variety of ways the tendency for these objects to concentrate in or near the cluster core. In agreement with simple theoretical arguments, we find that the characteristic time for this mass segregation process varies as 1/\mu. For models with very light tracers (\mu <~ 10^-2), which could represent free-floating planets or brown dwarfs, we find the expected depletion of light objects in the cluster core, but also sometimes a significant enhancement in the halo. Using these results we estimate the optical depth to gravitational microlensing by planetary mass objects or brown dwarfs in typical globular clusters. For some initial conditions, the optical depth in the halo due to very low-mass objects could be much greater than that of luminous stars. If we apply our results to M22, using the recent null detection of Sahu, Anderson, & King (2001), we find an upper limit of ~25% at the 63% confidence level for the current mass fraction of M22 in the form of very low-mass objects.Comment: Accepted for publication in ApJ. Minor revisions reflecting the new results of Sahu et al. on M22. 13 pages in emulateapj style, including 9 figures and 3 table

Classroom Management through Teacher Candidates’ Lenses: Transforming Learning Communities Through a Community of Practice

To better prepare teacher candidates for classroom management through attention to learning communities that affirm and support diverse students, including those effected by trauma, four instructors redesigned a required, undergraduate course. This study describes findings from three teacher candidate co-authors who were enrolled in that course. One semester after completing a course on classroom management and building community, candidates were asked to review their course products and other artifacts to consider what they learned and build upon their prior knowledge. Candidates used stimulated recall to respond to prompts on community building and relationships, gender and racial inclusivity, trauma sensitive practices, and the school to prison pipeline. Their perspectives contribute to understandings about how candidates engage in sense-making regarding classroom communities and classroom management

Easily retrievable objects among the NEO population

Asteroids and comets are of strategic importance for science in an effort to understand the formation, evolution and composition of the Solar System. Near-Earth Objects (NEOs) are of particular interest because of their accessibility from Earth, but also because of their speculated wealth of material resources. The exploitation of these resources has long been discussed as a means to lower the cost of future space endeavours. In this paper, we consider the currently known NEO population and define a family of so-called Easily Retrievable Objects (EROs), objects that can be transported from accessible heliocentric orbits into the Earth’s neighbourhood at affordable costs. The asteroid retrieval transfers are sought from the continuum of low energy transfers enabled by the dynamics of invariant manifolds; specifically, the retrieval transfers target planar, vertical Lyapunov and halo orbit families associated with the collinear equilibrium points of the Sun-Earth Circular Restricted Three Body problem. The judicious use of these dynamical features provides the best opportunity to find extremely low energy Earth transfers for asteroid material. A catalogue of asteroid retrieval candidates is then presented. Despite the highly incomplete census of very small asteroids, the ERO catalogue can already be populated with 12 different objects retrievable with less than 500 m/s of Δv. Moreover, the approach proposed represents a robust search and ranking methodology for future retrieval candidates that can be automatically applied to the growing survey of NEOs

Transient Tribo-Dynamics of Thermo-Elastic Compliant High-Performance Piston Skirts

Advanced piston technology for motorsport applications is driven through development of lightweight pistons with preferentially compliant short partial skirts. The preferential compliance is achieved through structural stiffening, such that a greater entrainment wedge is achieved at the skirt’s bottom edge through thermo-elastic deformation, whilst better conforming contact geometry at the top of the skirt. In practice, the combination of some of these conditions is intended to improve the load-carrying capacity and reduce friction. The approach is fundamental to the underlying ethos of race and high-performance engine technology. Contact loads of the order of 5 kN and contact kinematics in the range 0–35 m/s result in harsh transient tribological conditions. Therefore, piston design requires detailed transient analysis, which integrates piston dynamics, thermo-elastic distortion and transient elastohydrodynamics. The paper provides such a detailed analysis as well as verification of the same using non-invasive ultrasonic-assisted lubricant film thickness measurement from a fired engine under normal operating conditions, an approach not hitherto reported in literature. Good agreement is noted between measured film thickness and predictions

Secular changes in the quiescence of WZ Sge: the development of a cavity in the inner disk

We find a dimming during optical quiescence of the cataclysmic variable WZ Sge by about half a magnitude between superoutbursts. We connect the dimming with the development of a cavity in the inner part of the accretion disk. We suggest that, when the cavity is big enough, accretion of material is governed by the magnetic field of the white dwarf and pulsations from the weakly magnetic white dwarf appear. The time scale of forming the cavity is about a decade, and it persists throughout the whole quiescent phase. Such a cavity can be accommodated well by the proposed magnetic propeller model for WZ Sge, where during quiescence mass is being expelled by the magnetic white dwarf from the inner regions of the accretion disk to larger radii.Comment: 10 pages, 4 figures, accepted for publication in Astronomy and Astrophysics; following referee report, many textual changes, figures improved, more historic data added, conclusions unchange