402 research outputs found
The physical development of a privilaged group of African children
The height (body length) and the weight of children depend on a number of factors of which the most important are age, heredity and environment. In under-developed areas· the exact age of the children is often unknown and this may be one of the reasons why few attempts have been made to establish height and weight standards for African children
Magnetic and thermal properties of 4f-3d ladder-type molecular compounds
We report on the low-temperature magnetic susceptibilities and specific heats
of the isostructural spin-ladder molecular complexes L[M(opba)]_{3\cdot
xDMSOHO, hereafter abbreviated with LM (where L =
La, Gd, Tb, Dy, Ho and M = Cu, Zn). The results show that the Cu containing
complexes (with the exception of LaCu) undergo long range magnetic
order at temperatures below 2 K, and that for GdCu this ordering is
ferromagnetic, whereas for TbCu and DyCu it is probably
antiferromagnetic. The susceptibilities and specific heats of TbCu
and DyCu above have been explained by means of a model
taking into account nearest as well as next-nearest neighbor magnetic
interactions. We show that the intraladder L--Cu interaction is the predominant
one and that it is ferromagnetic for L = Gd, Tb and Dy. For the cases of Tb, Dy
and Ho containing complexes, strong crystal field effects on the magnetic and
thermal properties have to be taken into account. The magnetic coupling between
the (ferromagnetic) ladders is found to be very weak and is probably of dipolar
origin.Comment: 13 pages, 15 figures, submitted to Phys. Rev.
Moral reasoning and homosexuality: the acceptability of arguments about lesbian and gay issues
In the political arena, lesbian and gay issues have typically been contested on grounds of human rights, but with variable success. Using a moral developmental framework, the purpose of this study was to explore preferences for different types of moral arguments when thinking about moral dilemmas around lesbian and gay issues. The analysis presented here comprised data collected from 545 students at UK universities, who completed a questionnaire, part of which comprised a moral dilemma task. Findings of the study showed that respondents do not apply moral reasoning consistently, and do not (clearly) favour human rights reasoning when thinking about lesbian and gay issues. Respondents tended to favour reasoning supporting existing social structures and frameworks, therefore this study highlights the importance of structural change in effecting widespread attitude change in relation to lesbian and gay rights issues. The implications of the findings for moral education are also discussed.</p
A late requirement for Wnt and FGF signaling during activin-induced formation of foregut endoderm from mouse embryonic stem cells
AbstractHere we examine how BMP, Wnt, and FGF signaling modulate activin-induced mesendodermal differentiation of mouse ES cells grown under defined conditions in adherent monoculture. We monitor ES cells containing reporter genes for markers of primitive streak (PS) and its progeny and extend previous findings on the ability of increasing concentrations of activin to progressively induce more ES cell progeny to anterior PS and endodermal fates. We find that the number of Sox17- and Gsc-expressing cells increases with increasing activin concentration while the highest number of T-expressing cells is found at the lowest activin concentration. The expression of Gsc and other anterior markers induced by activin is prevented by treatment with BMP4, which induces T expression and subsequent mesodermal development. We show that canonical Wnt signaling is required only during late stages of activin-induced development of Sox17-expressing endodermal cells. Furthermore, Dkk1 treatment is less effective in reducing development of Sox17+ endodermal cells in adherent culture than in aggregate culture and appears to inhibit nodal-mediated induction of Sox17+ cells more effectively than activin-mediated induction. Notably, activin induction of Gsc-GFP+ cells appears refractory to inhibition of canonical Wnt signaling but shows a dependence on early as well as late FGF signaling. Additionally, we find a late dependence on FGF signaling during induction of Sox17+ cells by activin while BMP4-induced T expression requires FGF signaling in adherent but not aggregate culture. Lastly, we demonstrate that activin-induced definitive endoderm derived from mouse ES cells can incorporate into the developing foregut endoderm in vivo and adopt a mostly anterior foregut character after further culture in vitro
Social determinants of content selection in the age of (mis)information
Despite the enthusiastic rhetoric about the so called \emph{collective
intelligence}, conspiracy theories -- e.g. global warming induced by chemtrails
or the link between vaccines and autism -- find on the Web a natural medium for
their dissemination. Users preferentially consume information according to
their system of beliefs and the strife within users of opposite narratives may
result in heated debates. In this work we provide a genuine example of
information consumption from a sample of 1.2 million of Facebook Italian users.
We show by means of a thorough quantitative analysis that information
supporting different worldviews -- i.e. scientific and conspiracist news -- are
consumed in a comparable way by their respective users. Moreover, we measure
the effect of the exposure to 4709 evidently false information (satirical
version of conspiracy theses) and to 4502 debunking memes (information aiming
at contrasting unsubstantiated rumors) of the most polarized users of
conspiracy claims. We find that either contrasting or teasing consumers of
conspiracy narratives increases their probability to interact again with
unsubstantiated rumors.Comment: misinformation, collective narratives, crowd dynamics, information
spreadin
Exchange Interaction in Binuclear Complexes with Rare Earth and Copper Ions: A Many-Body Model Study
We have used a many-body model Hamiltonian to study the nature of the
magnetic ground state of hetero-binuclear complexes involving rare-earth and
copper ions. We have taken into account all diagonal repulsions involving the
rare-earth 4f and 5d orbitals and the copper 3d orbital. Besides, we have
included direct exchange interaction, crystal field splitting of the rare-earth
atomic levels and spin-orbit interaction in the 4f orbitals. We have identified
the inter-orbital repulsion, U and crystal field parameter,
as the key parameters involved in controlling the type of exchange
interaction between the rare earth and copper 3d spins. We have explored
the nature of the ground state in the parameter space of U, ,
spin-orbit interaction strength and the filling n. We find
that these systems show low-spin or high-spin ground state depending on the
filling of the levels of the rare-earth ion and ground state spin is
critically dependent on U and . In case of half-filling
(Gd(III)) we find a reentrant low-spin state as U is increased, for
small values of , which explains the recently reported apparent
anomalous anti-ferromagnetic behaviour of Gd(III)-radical complexes. By varying
U we also observe a switch over in the ground state spin for other
fillings . We have introduced a spin-orbit coupling scheme which goes beyond
L-S or j-j coupling scheme and we find that spin-orbit coupling does not
significantly alter the basic picture.Comment: 22 pages, 11 ps figure
A narrative analysis of career transition themes and outcomes using chaos theory as a guiding metaphor
In a rapidly changing world of work little research exists on mid-career transitions. We investigated these using the open-systems approach of chaos theory as a guiding metaphor and conducted interviews with seven mid-career individuals chosen for their experience of a significant mid-career transition. Four common themes were identified through narrative analysis, where ‘false starts’ to a career were a common experience prior to finding a career ‘fit’. Career transitions, precipitated by a trigger state and/or event such as a period of disillusionment, were an important part of this ‘finding a fit’ process. Overall, career success outcomes were shaped by a combination of chaos elements: chance, unplanned events, and non-linearity of resultant outcomes. We discuss implications for future research and for practice
Population-level effects of human papillomavirus vaccination programs on infections with nonvaccine genotypes
We analyzed human papillomavirus (HPV) prevalences during prevaccination and postvaccination periods to consider possible changes in nonvaccine HPV genotypes after introduction of vaccines that confer protection against 2 high-risk types, HPV16 and HPV18. Our meta-analysis included 9 studies with data for 13,886 girls and women ≤19 years of age and 23,340 women 20–24 years of age. We found evidence of cross-protection for HPV31 among the younger age group after vaccine introduction but little evidence for reductions of HPV33 and HPV45. For the group this same age group, we also found slight increases in 2 nonvaccine high-risk HPV types (HPV39 and HPV52) and in 2 possible high-risk types (HPV53 and HPV73). However, results between age groups and vaccines used were inconsistent, and the increases had possible alternative explanations; consequently, these data provided no clear evidence for type replacement. Continued monitoring of these HPV genotypes is important
Theory of Coexistence of Superconductivity and Ferroelectricity : A Dynamical Symmetry Model
We propose and investigate a model for the coexistence of Superconductivity
(SC) and Ferroelectricity (FE) based on the dynamical symmetries for
the pseudo-spin SC sector, for the displaced oscillator FE sector, and
for the composite system. We assume a minimal
symmetry-allowed coupling, and simplify the hamiltonian using a double mean
field approximation (DMFA). A variational coherent state (VCS) trial
wave-function is used for the ground state: the energy, and the relevant order
parameters for SC and FE are obtained. For positive sign of the SC-FE coupling
coefficient, a non-zero value of either order parameter can suppress the other
(FE polarization suppresses SC and vice versa). This gives some support to
"Matthias' Conjecture" [1964], that SC and FE tend to be mutually exclusive.
For such a Ferroelectric Superconductor we predict: a) the SC gap
(and ) will increase with increasing applied pressure when pressure
quenches FE as in many ferroelectrics, and b) the FE polarization will increase
with increaesing magnetic field up to . The last result is equivalent to
the prediction of a new type of Magneto-Electric Effect in a coexistent SC-FE
material. Some discussion will be given of the relation of these results to the
cuprate superconductors.Comment: 46 page
The PHENIX Experiment at RHIC
The physics emphases of the PHENIX collaboration and the design and current
status of the PHENIX detector are discussed. The plan of the collaboration for
making the most effective use of the available luminosity in the first years of
RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program
available at http://www.rhic.bnl.gov/phenix
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