14,558 research outputs found
Open science and modified funding lotteries can impede the natural selection of bad science.
Assessing scientists using exploitable metrics can lead to the degradation of research methods even without any strategic behaviour on the part of individuals, via 'the natural selection of bad science.' Institutional incentives to maximize metrics like publication quantity and impact drive this dynamic. Removing these incentives is necessary, but institutional change is slow. However, recent developments suggest possible solutions with more rapid onsets. These include what we call open science improvements, which can reduce publication bias and improve the efficacy of peer review. In addition, there have been increasing calls for funders to move away from prestige- or innovation-based approaches in favour of lotteries. We investigated whether such changes are likely to improve the reproducibility of science even in the presence of persistent incentives for publication quantity through computational modelling. We found that modified lotteries, which allocate funding randomly among proposals that pass a threshold for methodological rigour, effectively reduce the rate of false discoveries, particularly when paired with open science improvements that increase the publication of negative results and improve the quality of peer review. In the absence of funding that targets rigour, open science improvements can still reduce false discoveries in the published literature but are less likely to improve the overall culture of research practices that underlie those publications
Ergodic Transport Theory, periodic maximizing probabilities and the twist condition
The present paper is a follow up of another one by A. O. Lopes, E. Oliveira
and P. Thieullen which analyze ergodic transport problems. Our main focus will
a more precise analysis of case where the maximizing probability is unique and
is also a periodic orbit.
Consider the shift T acting on the Bernoulli space \Sigma={1, 2, 3,..,
d}^\mathbb{N} A:\Sigma \to \mathbb{R} a Holder potential.
Denote m(A)=max_{\nu is an invariant probability for T} \int A(x) \; d\nu(x)
and, \mu_{\infty,A}, any probability which attains the maximum value. We assume
this probability is unique (a generic property). We denote \T the bilateral
shift. For a given potential Holder A:\Sigma \to \mathbb{R}, we say that a
Holder continuous function W: \hat{\Sigma} \to \mathbb{R} is a involution
kernel for A, if there is a Holder function A^*:\Sigma \to \mathbb{R}, such
that, A^*(w)= A\circ \T^{-1}(w,x)+ W \circ \T^{-1}(w,x) - W(w,x). We say that
A^* is a dual potential of A. It is true that m(A)=m(A^*). We denote by V the
calibrated subaction for A, and, V^* the one for A^*. We denote by I^* the
deviation function for the family of Gibbs states for \beta A, when \beta \to
\infty.
For each x we get one (more than one) w_x such attains the supremum above.
That is, solutions of V(x) = W(w_x,x) - V^* (w_x)- I^*(w_x).
A pair of the form (x,w_x) is called an optimal pair. If \T is the shift
acting on (x,w) \in {1, 2, 3,.., d}^\mathbb{Z}, then, the image by \T^{-1} of
an optimal pair is also an optimal pair.
Theorem - Generically, in the set of Holder potentials A that satisfy
(i) the twist condition,
(ii) uniqueness of maximizing probability which is supported in a periodic
orbit, the set of possible optimal w_x, when x covers the all range of possible
elements x in \in \Sigma, is finite
Geodesic analysis and steady accretion on a traversable wormhole
In this work, we analyze the behavior of light and matter as they pass near
and through a traversable wormhole. In particular, we study the trajectories of
massive and massless particles and the dust accretion around a traversable
wormhole previously reported in Eur. Phys. J. C \textbf{82} (2022) no.7, 605.
For massive particles, we integrate the trajectory equation for ingoing and
outgoing geodesics and classify the orbits of particles scattered by the
wormhole in accordance with their asymptotic behavior far from the throat. We
represent all the time--like trajectories in an embedding surface where it is
shown explicitly the trajectories of i) particles that deviate from the throat
and remain in the same universe, ii) particles that traverse the wormhole to
another universe, and iii) particles that get trapped in the wormhole in
unstable circular orbits. For the massless particles, we numerically integrate
the trajectory equation to show the ray-tracing around the wormhole specifying
the particles that traverse the wormhole and those that are only deviated by
the throat. For the study of accretion, we consider the steady and spherically
symmetric accretion of dust. Our results show that the wormhole parameters can
significantly affect the behavior of light and matter near the wormhole. Some
comparisons with the behavior of matter around black holes are made
Reaching the boundary between stellar kinematic groups and very wide binaries. III. Sixteen new stars and eight new wide systems in the beta Pictoris moving group
Aims. We look for common proper motion companions to stars of the nearby
young beta Pictoris moving group. Methods. First, we compiled a list of 185
beta Pictoris members and candidate members from 35 representative works. Next,
we used the Aladin and STILTS virtual observatory tools, and the PPMXL proper
motion and Washington Double Star catalogues to look for companion candidates.
The resulting potential companions were subjects of a dedicated
astro-photometric follow-up using public data from all-sky surveys. After
discarding 67 sources by proper motion and 31 by colour-magnitude diagrams, we
obtained a final list of 36 common proper motion systems. The binding energy of
two of them is perhaps too small to be considered physically bound. Results. Of
the 36 pairs and multiple systems, eight are new, 16 have only one stellar
component previously classified as a beta Pictoris member, and three have
secondaries at or below the hydrogen-burning limit. Sixteen stars are reported
here for the first time as moving group members. The unexpected large number of
high-order multiple systems, 12 triples and two quadruples among 36 systems,
may suggest a biased list of members towards close binaries or an increment of
the high-order-multiple fraction for very wide systems.Comment: A&A in pres
Religiosity and Sexual Risk Behaviors Among Latina Adolescents: Trends from 1995 to 2008
Purpose: The purpose of this study was to determine trends in the influence of religiosity on sexual activity of Latina adolescents in the United States from 1995 to 2008 and to determine if differences existed between the Mexican American and other Latina groups.
Methods: The sample comprised the subset of unmarried, 15–21-year-old (mean 17 years) Latina female respondents in the 1995 (n=267), 2002 (n=306), and 2006–2008 (n=400) National Survey of Family Growth (NSFG) datasets. Associations between religiosity (importance of religion and service attendance) and history of ever having sex, number of sex partners, and age of sexual debut were investigated.
Results: Less than one half of Latinas in 1995 (44%) and in 2006–2008 (44%) reported that religion was very important to them, whereas in 2002, 50% reported it was important. Only in 1995 did Latinas who viewed religion as very important have a significantly lower level of sexual initiation. In 1995 and in 2006–2008, Latinas who held religion as very important had significantly fewer partners. In all three cohorts, the higher religious importance group had higher virgin survival rates. Across cohorts, approximately one third of respondents reported frequent religious attendance. In all cohorts, frequent attenders were less likely to have had sex, had fewer partners, and had older age at sexual debut. The survival rate as virgins for Mexican origin Latinas was higher in 1995 and 2002 compared to non-Mexican Latinas but was almost the same in 2006–2008.
Conclusions: Religiosity had a protective association with sexual activity among Latina adolescents. The association of importance of religion with sexual activity has diminished from 1995 to 2008, however, whereas the importance of service attendance has remained stable. The influence of religion was more apparent among the Latinas of Mexican origin, but this greater influence also diminished by 2006–2008
Submillimeter polarisation and magnetic field properties in the envelopes of proto-planetary nebulae CRL 618 and OH 231.8+4.2
We have carried out continuum and line polarisation observations of two
Proto-planetary nebulae (PPNe), CRL 618 and OH 231.8+4.2, using the
Submillimeter Array (SMA) in its compact configuration. The frequency range of
observations, 330-345 GHz, includes the CO(J=3-2) line emission. CRL 618 and OH
231.8+4.2 show quadrupolar and bipolar optical lobes, respectively, surrounded
by a dusty envelope reminiscent of their AGB phase. We report a detection of
dust continuum polarised emission in both PPNe above 4 sigma but no molecular
line polarisation detection above a 3 sigma limit. OH 231.8+4.2 is slightly
more polarised on average than CRL 618 with a mean fractional polarisation of
4.3 and 0.3 per cent, respectively. This agrees with the previous finding that
silicate dust shows higher polarisation than carbonaceous dust. In both
objects, an anti-correlation between the fractional polarisation and the
intensity is observed. Neither PPNe show a well defined toroidal equatorial
field, rather the field is generally well aligned and organised along the polar
direction. This is clearly seen in CRL 618 while in the case of OH 231.8+4.2,
the geometry indicates an X-shaped structure coinciding overall with a
dipole/polar configuration. However in the later case, the presence of a
fragmented and weak toroidal field should not be discarded. Finally, in both
PPNe, we observed that the well organised magnetic field is parallel with the
major axis of the 12CO outflow. This alignment could indicate the presence of a
magnetic outflow launching mechanism. Based on our new high resolution data we
propose two scenarios to explain the evolution of the magnetic field in evolved
stars.Comment: 11 pages, 8 figures and 1 table. Accepted for publication in the
Monthly Notices of the Royal Astronomical Societ
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