5,698 research outputs found
Body composition data from the rat subjects of Cosmos 1129 experiment K-316
The effects of 18.5 days of weightlessness on the body composition of young, growing, male laboratory rats were examined. Three groups of 5 rats each were examined. It is indicated that exposure of young, growing, male rats to 18.5 days of weightlessness produces: (1) no effect on the quantity of fat stored by the body; (2) a slight reduction in the quantity of fat free tissue laid down by the body; (3) a small reduction in the fraction of water contained by the fat free body mass; (4) a similar reduction in the fraction of water contained by the fat free skin and fat free carcass; (5) a shift in relative distribution of the total body water from skin to viscera; (6) a diminution in the fraction of extracellular water contained by the fat free body; (7) no effect on the fraction of total skeletal musculature contained by the fat free body, as indicated by body creatine content; (8) a sizeable reduction in the fraction of bone mineral contained by the fat free body, as calculated from body calcium content. The nature of the physiological changes induced by unloading from Earth gravity in the mammalian organism are illustrated
Constructing Infinitary Quotient-Inductive Types
This paper introduces an expressive class of quotient-inductive types, called
QW-types. We show that in dependent type theory with uniqueness of identity
proofs, even the infinitary case of QW-types can be encoded using the
combination of inductive-inductive definitions involving strictly positive
occurrences of Hofmann-style quotient types, and Abel's size types. The latter,
which provide a convenient constructive abstraction of what classically would
be accomplished with transfinite ordinals, are used to prove termination of the
recursive definitions of the elimination and computation properties of our
encoding of QW-types. The development is formalized using the Agda theorem
prover.Comment: The accompanying Agda code can be found at
https://doi.org/10.17863/CAM.4818
Algebraic Isomorphisms and Spectra of Triangular Limit Algebras: Erratum
We have found an error in the proof of Theorem 4.1 in [2]. This error affects only Theorems 4.1 and 4.3. As we have been unable to find an alternative proof of Theorem 4.1, we do not know if these theorems are true in full generality. Restricted to limit algebras generated by their order-preserving normalizers, the proof is correct. The theorems are known to be true in this case by somewhat different methods [1]
Fetal Heart Rate Decelerations in Women with Sleep-Disordered Breathing
Emerging literature has shown that women with sleep-disordered breathing (SDB) have increased risk for gestational hypertension/preeclampsia and gestational diabetes. Case reports suggest an association between maternal apnea and fetal heart rate deceleration but data are lacking on how maternal sleep impacts fetal health. Since decelerations may be associated with adverse outcomes, we sought to determine whether fetal heart rate decelerations were associated with SDB. A cohort study of third trimester pregnant women with a singleton fetus was conducted. Participants underwent a home sleep test with continuous portable electronic fetal monitoring. SDB was defined as a respiratory disturbance index (RDI)â„10 events/hour. The temporality between a respiratory event and fetal heart rate decelerations was determined to be present if a deceleration occurred \u3c 30 s after a respiratory event. Forty women were included with mean (±SD) age, BMI, and gestational age of 32.0±5.5 years, 37.1±8.0 kg/m(2), and 34.6±2.4 weeks respectively. Overall, n=23 (57.5%) women had SDB. Thirty-seven late decelerations were observed in 18 women; of these, 84% were temporally associated with a respiratory event. Nine of the 18 women (50%) had SDB. Ten prolonged decelerations were observed in 6 women of which nine (90%) were temporally associated with a respiratory event. Five of the six women (83%) had an RDIâ„10. These initial data suggest that, in this population, the majority of both late and prolonged fetal heart rate decelerations occur with a maternal respiratory event. Since respiratory events are characteristic of maternal SDB, this raises the possibility that SDB may influence fetal well-being
Universally Coupled Massive Gravity
We derive Einstein's equations from a linear theory in flat space-time using
free-field gauge invariance and universal coupling. The gravitational potential
can be either covariant or contravariant and of almost any density weight. We
adapt these results to yield universally coupled massive variants of Einstein's
equations, yielding two one-parameter families of distinct theories with spin 2
and spin 0. The Freund-Maheshwari-Schonberg theory is therefore not the unique
universally coupled massive generalization of Einstein's theory, although it is
privileged in some respects. The theories we derive are a subset of those found
by Ogievetsky and Polubarinov by other means. The question of positive energy,
which continues to be discussed, might be addressed numerically in spherical
symmetry. We briefly comment on the issue of causality with two observable
metrics and the need for gauge freedom and address some criticisms by
Padmanabhan of field derivations of Einstein-like equations along the way.Comment: Introduction notes resemblance between Einstein's discovery process
and later field/spin 2 project; matches journal versio
In defence of the familiar : understanding conservatism in concert selection amongst classical music audiences
Since the establishment of a classical music canon in the 19th century, classical music culture has historically been focused on a stable set of masterpieces by genius composers predominantly from the classical and romantic periods. A small number of composers continue to dominate programming to this day. Many classical music organisations are keen to programme music beyond this narrow repertoire and to showcase new or unfamiliar works. The need to sell tickets, however, is often an obstacle, with organisations far more confident in the ability of big hits to attract large crowds. This article explores the experiences and opinions of classical music concertgoers in relation to familiar and unfamiliar music, providing a number of reasons as to why audiences may choose to hear well-known pieces rather than new works. This paper reports on one strand of a qualitative study with 42 individuals who booked tickets for one of two concert series consisting of core and populist repertoire, respectively. Semi-structured interviews were carried out to explore the reasons for their choices and their experiences of attending live concerts. These interviews showed that most participants did indeed have a clear preference for hearing music that was familiar to them, and only frequent attenders relished the challenge of unknown music. Participants felt that listening to familiar music was usually a more enjoyable experience than hearing something new. They rarely spoke of becoming bored with over-familiar music, perhaps because the live concert experience brings a sense of freshness to even the most familiar work
Nonaxisymmetric Magnetorotational Instability in Proto-Neutron Stars
We investigate the stability of differentially rotating proto-neutron stars
(PNSs) with a toroidal magnetic field. Stability criteria for nonaxisymmetric
MHD instabilities are derived using a local linear analysis. PNSs are expected
to have much stronger radial shear in the rotation velocity compared to normal
stars. We find that nonaxisymmetric magnetorotational instability (NMRI) with a
large azimuthal wavenumber is dominant over the kink mode () in
differentially rotating PNSs. The growth rate of the NMRI is of the order of
the angular velocity which is faster than that of the kink-type
instability by several orders of magnitude. The stability criteria are
analogous to those of the axisymmetric magnetorotational instability with a
poloidal field, although the effects of leptonic gradients are considered in
our analysis. The NMRI can grow even in convectively stable layers if the
wavevectors of unstable modes are parallel to the restoring force by the
Brunt-V\"ais\"al\"a oscillation. The nonlinear evolution of NMRI could amplify
the magnetic fields and drive MHD turbulence in PNSs, which may lead to
enhancement of the neutrino luminosity.Comment: 24pages, 7figures, Accepted for publication in the Astrophysical
Journal (December 12, 2005
A principled approach to programming with nested types in Haskell
Initial algebra semantics is one of the cornerstones of the theory of modern functional programming languages. For each inductive data type, it provides a Church encoding for that type, a build combinator which constructs data of that type, a fold combinator which encapsulates structured recursion over data of that type, and a fold/build rule which optimises modular programs by eliminating from them data constructed using the buildcombinator, and immediately consumed using the foldcombinator, for that type. It has long been thought that initial algebra semantics is not expressive enough to provide a similar foundation for programming with nested types in Haskell. Specifically, the standard folds derived from initial algebra semantics have been considered too weak to capture commonly occurring patterns of recursion over data of nested types in Haskell, and no build combinators or fold/build rules have until now been defined for nested types. This paper shows that standard folds are, in fact, sufficiently expressive for programming with nested types in Haskell. It also defines buildcombinators and fold/build fusion rules for nested types. It thus shows how initial algebra semantics provides a principled, expressive, and elegant foundation for programming with nested types in Haskell
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