1,573 research outputs found
Modelling regional variation of first-time births in Denmark 1980-1994 by an age-period-cohort model
Despite the small size of Denmark, there have traditionally been rather consistent regional differences in fertility rates. We apply the statistical age-period-cohort model to include the effect of these three time-related factors thereby concisely illuminating the regional differences of first-time births in Denmark. From the Fertility of Women and Couples Dataset we obtain data on number of births by nulliparous women by year (1980-1994), age (15-45) and county of residence. We show that the APC-model describes the fertility rates of nulliparous women satisfactorily. To catch the regional variation an interaction parameter between age and county is necessary, which provides a surprisingly good description suggesting that the county-specific age-distributions of first-time fertility rates differ. Our results are in general agreement with the 'moral geography' concepts of Tonboe (2001).age-period-cohort models, Denmark, fertility, fertility rate, nulliparous women, regional variation
Social Transmission of Experience of Agency: An Experimental Study
The sense of controlling one’s own actions is fundamental to normal human mental function, and also underlies concepts of social responsibility for action. However, it remains unclear how the wider social context of human action influences sense of agency. Using a simple experimental design, we investigated, for the first time, how observing the action of another person or a robot could potentially influence one’s own sense of agency. We assessed how observing another’s action might change the perceived temporal relationship between one’s own voluntary actions and their outcomes, which has been proposed as an implicit measure of sense of agency. Working in pairs, participants chose between two action alternatives, one rewarded more frequently than the other, while watching a rotating clock hand. They judged, in separate blocks, either the time of their own action, or the time of a tone that followed the action. These were compared to baseline judgements of actions alone, or tones alone, to calculate the perceptual shift of action toward outcome and vice versa. Our design focused on how these two dependent variables, which jointly provide an implicit measure of sense of agency, might be influenced by observing another’s action. In the observational group, each participant could see the other’s actions. Multivariate analysis showed that the perceived time of action and tone shifted progressively toward the actual time of outcome with repeated experience of this social situation. No such progressive change occurred in other groups for whom a barrier hid participants’ actions from each other. However, a similar effect was observed in the group that viewed movements of a human-like robotic hand, rather than actions of another person. This finding suggests that observing the actions of others increases the salience of the external outcomes of action and this effect is not unique to observing human agents. Social contexts in which we see others controlling external events may play an important role in mentally representing the impact of our own actions on the external world
Density waves theory of the capsid structure of small icosahedral viruses
We apply Landau theory of crystallization to explain and to classify the
capsid structures of small viruses with spherical topology and icosahedral
symmetry. We develop an explicit method which predicts the positions of centers
of mass for the proteins constituting viral capsid shell. Corresponding density
distribution function which generates the positions has universal form without
any fitting parameter. The theory describes in a uniform way both the
structures satisfying the well-known Caspar and Klug geometrical model for
capsid construction and those violating it. The quasiequivalence of protein
environments in viral capsid and peculiarities of the assembly thermodynamics
are also discussed.Comment: 8 pages, 3 figur
Defect free global minima in Thomson's problem of charges on a sphere
Given unit points charges on the surface of a unit conducting sphere,
what configuration of charges minimizes the Coulombic energy ? Due to an exponential rise in good local minima, finding global
minima for this problem, or even approaches to do so has proven extremely
difficult. For \hbox{} recent theoretical work based on
elasticity theory, and subsequent numerical work has shown, that for --1000 adding dislocation defects to a symmetric icosadeltahedral lattice
lowers the energy. Here we show that in fact this approach holds for all ,
and we give a complete or near complete catalogue of defect free global minima.Comment: Revisions in Tables and Reference
Capacitive coupling of atomic systems to mesoscopic conductors
We describe a technique that enables a strong, coherent coupling between
isolated neutral atoms and mesoscopic conductors. The coupling is achieved by
exciting atoms trapped above the surface of a superconducting transmission line
into Rydberg states with large electric dipole moments, that induce voltage
fluctuations in the transmission line. Using a mechanism analogous to cavity
quantum electrodynamics an atomic state can be transferred to a long-lived mode
of the fluctuating voltage, atoms separated by millimeters can be entangled, or
the quantum state of a solid state device can be mapped onto atomic or photonic
states.Comment: 4 pages, including one figure. v2: Improved discussion of surface
effect
Stereospecific dihaloalkane binding in a pH-sensitive cavity in cubic insulin crystals.
Elasticity Theory and Shape Transitions of Viral Shells
Recently, continuum elasticity theory has been applied to explain the shape
transition of icosahedral viral capsids - single-protein-thick crystalline
shells - from spherical to buckled/faceted as their radius increases through a
critical value determined by the competition between stretching and bending
energies of a closed 2D elastic network. In the present work we generalize this
approach to capsids with non-icosahedral symmetries, e.g., spherocylindrical
and conical shells. One key new physical ingredient is the role played by
nonzero spontaneous curvature. Another is associated with the special way in
which the energy of the twelve topologically-required five-fold sites depends
on the background local curvature of the shell in which they are embedded.
Systematic evaluation of these contributions leads to a shape phase diagram in
which transitions are observed from icosahedral to spherocylindrical capsids as
a function of the ratio of stretching to bending energies and of the
spontaneous curvature of the 2D protein network. We find that the transition
from icosahedral to spherocylindrical symmetry is continuous or weakly
first-order near the onset of buckling, leading to extensive shape degeneracy.
These results are discussed in the context of experimentally observed
variations in the shapes of a variety of viral capsids.Comment: 53 pages, 17 figure
Chiral Quasicrystalline Order and Dodecahedral Geometry in Exceptional Families of Viruses
On the example of exceptional families of viruses we i) show the existence of
a completely new type of matter organization in nanoparticles, in which the
regions with a chiral pentagonal quasicrystalline order of protein positions
are arranged in a structure commensurate with the spherical topology and
dodecahedral geometry, ii) generalize the classical theory of quasicrystals
(QCs) to explain this organization, and iii) establish the relation between
local chiral QC order and nonzero curvature of the dodecahedral capsid faces.Comment: 8 pages, 3 figure
Distinción de variantes en color de Serapias perez-chiscanoi (Orchidaceae) en relación con táxones de la Península Ibérica
Serapias perez-chiscanoi has a stable and uniform appearance with green flowers. Throughout its distribution area, however, plants have been found with deviant pink to red flowers that show similarities with other taxa that are occasionally pale flowered. S. perez-chiscanoi is easy to differentiate from S. cordigera subsp. cordigera by the colour of the flowers (S. cordigera subsp. cordigera has red to purple flowers) and the fact that the hypochile dimensions of S. perez-chiscanoi are significantly smaller. It is, however, more difficult to distinguish it from individuals of S. cordigera subsp. gentilii with pale flowers, which occur frequently. The two taxa differ in colour pattern and floral dimensions, especially the hypochile length, which is shorter in S. perez-chiscanoi. Pale-flowered individuals of another species, S. parviflora, are easily distinguished by their significantly smaller flowers. S. perez-chiscanoi occurs in Spain in the autonomous regions of Extremadura and Castilla-La Mancha and in Portugal, S. cordigera subsp. gentilii seems to occur along the coastal regions of SW Portugal, while S. cordigera subsp. cordigera and S. parviflora are distributed throughout the Iberian Peninsula.La Serapias perez-chiscanoi tiene una apariencia estable y uniforme con flores verdes. Sin embargo, a lo largo de su área de distribución, se han encontrado ejemplares de flores con coloraciones desviantes de color rosa hasta rojo que muestran similitudes con otros táxones que presentan ocasionalmente flores pálidas. Serapias perez-chiscanoi es fácil de diferenciar con respecto a S. cordigera subsp. cordigera por el color de las flores (S. cordigera subsp. cordigera tiene flores de rojizas hasta púrpura) y por las dimensiones significativamente más peque - ñas del hipoquilo de S. perez-chiscanoi. Sin embargo es más difícil hacer una distinción con respecto a S. cordigera subsp. gentilii, ya que los individuos de este taxon presentan flores pálidas, lo que ocurre con frecuencia. Estos dos táxones se diferencian por el patrón de colores y por las pequeñas dimensiones de las piezas florales, especialmente el tamaño del hipoquilo más corto en S. perez-chiscanoi. Los individuos de flores pálidas de S. parviflora se pueden distinguir fácilmente gracias a sus flores de pequeño tamaño. Serapias perez-chiscanoi se localiza en España en las comunidades autónomas de Extremadura y Castilla-La Mancha y en Portugal, S. cordigera subsp. gentilii se puede encontrar en las zonas costeras del suroeste de Portugal, mientras que S. cordigera subsp. cordigera y S. parviflora se encuentran en la mayor parte de la Península Ibéric
Long-term renal safety profile of ibandronate 6 mg infused over 15 minutes
In an earlier study, intravenous (i.v.) ibandronate 6 mg administered every 3-4 weeks had a similarly good renal safety profile whether infused over 15 or 60 min in women with breast cancer and bone metastases. This current study focuses on the renal safety of the extended use of ibandronate
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