1,557 research outputs found
Cemented Thompson versus cemented bipolar prostheses for femoral neck fractures
To compare early functional outcomes, complications, and mortality in elderly patients treated with the less costly, cemented Thompson prosthesis or the cemented bipolar prosthesis in order to identify factors affecting outcomes. Records of 303 patients with femoral neck fractures treated with the cemented Thompson monoblock prosthesis (n=206) or the cemented bipolar prosthesis (n=97) were reviewed. The choice of prosthesis was solely determined by surgeon's preference. Data relating to patient demographics, clinical and residential status, mobility, mental function, mortality, and complications during hospitalisation and rehabilitation were collected. After adjusting for confounding variables, independent postoperative indoor mobility was associated with preoperative indoor mobility (p=0.002) and mental function (p=0.001), whereas postoperative outdoor mobility was associated with preoperative outdoor mobility (p=0.003), daily living activity (p=0.02), and mental function (p=0.02). Mortality within 6 months was only associated with poor mental function (p=0.009). At 6-month follow-up, there was no significant difference between the 2 types of prosthesis in terms of functional outcomes, mortality and complication rates. In elderly patients with limited mobility, treatment with the bipolar prosthesis was not associated with better short-term outcomes than those receiving the Thompson prosthesis
Collective flow in central Au-Au collisions at 150, 250 and 400 A MeV
Radial collective flow and thermalization are studied in gold on gold
collisions at 150, 250 and 400 A MeV bombarding energies with a
relativistically covariant formulation of a QMD code. We find that radial flow
and "thermal" energies calculated for all the charged fragments agree
reasonably with the experimental values. The experimental hardware filter at
small angles used in the FOPI experiments at higher energies selects mainly the
thermalized particles.Comment: 4 pages with 4 EPS figures included. Version accepted for publication
in Phys. Rev.
Correction of cone index for soil water content differences in a coastal plain soil
Soil penetration resistance (cone index) varies with water content. The field variation of water
content could mask treatment differences. The correction of cone index data to a single water
content would help prevent this. We used equations from TableCurve software and from the
literature to correct cone indices for differences in soil water contents. Data were taken from two
field experiments where cotton (Gossypium hirsutum L.) was grown using conventional and
conservation tillage without irrigation, and beans (Phaseolus vulgaris L.) were grown using
conventional tillage with microirrigation. Boundary conditions based on hard, dry and soft. wet
soils were imposed on the equations. Equations fit the data with coefficients of determination
ranging from 0.55 to 0.92 and error mean squares from 1.37 to 6.35. After correction, cone index
dependence on water content was reduced. A single-equation correction did not always fit the data
across all treatments. Separate corrections, based on treatment, might be required. When corrections
required multiple equations, differences may be real or may be a manifestation of the
correction differences. In this case, the correction may not be feasible (unless some future work
can coordinate different equations and assure a uniform correction)
Multi-layer light trapping structures for enhanced solar collection
Light trapping is a commonly used technique for enhancing the efficiency of solar collection in many photovoltaic (PV) devices. In this paper, we present the design of multi-layer light trapping structures that can potentially be retrofitted, or directly integrated, onto crystalline or amorphous silicon solar panels for enhanced optical collection at normal and extreme angle of incidence. This approach can improve the daily optical collection performance of solar panel with and without internally integrated light trapping structure by up to 7.18% and 159.93%, respectively. These improvements predict an enhancement beyond many research level and commercially deployed light trapping technologies. We further enhance this performance by combining our multi-layer optics with high refractive index materials to achieve a daily optical collection of up to 32.20% beyond leading light trapping structures. Our additive light trapping designs could enable the upgradeability of older PV technologies and can be tailored to optimally operate at unique angular ranges for building exteriors or over a wide range of incidence angle for applications such as unmanned aerial vehicles
Transforming fixed-length self-avoiding walks into radial SLE_8/3
We conjecture a relationship between the scaling limit of the fixed-length
ensemble of self-avoiding walks in the upper half plane and radial SLE with
kappa=8/3 in this half plane from 0 to i. The relationship is that if we take a
curve from the fixed-length scaling limit of the SAW, weight it by a suitable
power of the distance to the endpoint of the curve and then apply the conformal
map of the half plane that takes the endpoint to i, then we get the same
probability measure on curves as radial SLE. In addition to a non-rigorous
derivation of this conjecture, we support it with Monte Carlo simulations of
the SAW. Using the conjectured relationship between the SAW and radial SLE, our
simulations give estimates for both the interior and boundary scaling
exponents. The values we obtain are within a few hundredths of a percent of the
conjectured values
Understanding the nature of and through nonleptonic B Decays
We consider the nonleptonic B decays and , involving the newly discovered and the
states. We find that experiments indicate disagreement with model
calculations of their properties and/or breakdown of the factorization
assumption for these decays . We point out that decays involving mesons
where the resonances can be produced via the weak decay of the quark
can provide further information about the nature of these newly discovered
states. We also propose a model to calculate the two body nonleptonic decays , if the and are
interpreted as and molecules.Comment: 14 pages LaTeX; additional reference, notational corrections and
minor clarifications of tex
Dynamically avoiding fine-tuning the cosmological constant: the "Relaxed Universe"
We demonstrate that there exists a large class of action functionals of the
scalar curvature and of the Gauss-Bonnet invariant which are able to relax
dynamically a large cosmological constant (CC), whatever it be its starting
value in the early universe. Hence, it is possible to understand, without
fine-tuning, the very small current value of the CC as compared to its
theoretically expected large value in quantum field theory and string theory.
In our framework, this relaxation appears as a pure gravitational effect, where
no ad hoc scalar fields are needed. The action involves a positive power of a
characteristic mass parameter, M, whose value can be, interestingly enough, of
the order of a typical particle physics mass of the Standard Model of the
strong and electroweak interactions or extensions thereof, including the
neutrino mass. The model universe emerging from this scenario (the "Relaxed
Universe") falls within the class of the so-called LXCDM models of the cosmic
evolution. Therefore, there is a "cosmon" entity X (represented by an effective
object, not a field), which in this case is generated by the effective
functional and is responsible for the dynamical adjustment of the cosmological
constant. This model universe successfully mimics the essential past epochs of
the standard (or "concordance") cosmological model (LCDM). Furthermore, it
provides interesting clues to the coincidence problem and it may even connect
naturally with primordial inflation.Comment: LaTeX, 63 pp, 8 figures. Extended discussion. Version accepted in
JCA
Normal Cones and Thompson Metric
The aim of this paper is to study the basic properties of the Thompson metric
in the general case of a real linear space ordered by a cone . We
show that has monotonicity properties which make it compatible with the
linear structure. We also prove several convexity properties of and some
results concerning the topology of , including a brief study of the
-convergence of monotone sequences. It is shown most of the results are
true without any assumption of an Archimedean-type property for . One
considers various completeness properties and one studies the relations between
them. Since is defined in the context of a generic ordered linear space,
with no need of an underlying topological structure, one expects to express its
completeness in terms of properties of the ordering, with respect to the linear
structure. This is done in this paper and, to the best of our knowledge, this
has not been done yet. The Thompson metric and order-unit (semi)norms
are strongly related and share important properties, as both are
defined in terms of the ordered linear structure. Although and
are only topological (and not metrical) equivalent on , we
prove that the completeness is a common feature. One proves the completeness of
the Thompson metric on a sequentially complete normal cone in a locally convex
space. At the end of the paper, it is shown that, in the case of a Banach
space, the normality of the cone is also necessary for the completeness of the
Thompson metric.Comment: 36 page
Recent developments in unconventional superconductivity theory
The review of recent developments in the unconventional superconductivity
theory is given. In the fist part I consider the physical origin of the Kerr
rotation polarization of light reflected from the surface of superconducting
. Then the comparison of magneto-optical responses in
superconductors with orbital and spin spontaneous magnetization is presented.
The latter result is applied to the estimation of the magneto-optical
properties of neutral superfluids with spontaneous magnetization. The second
part is devoted to the natural optical activity or gyrotropy properties of
noncentrosymmetric metals in their normal and superconducting states. The
temperature behavior of the gyrotropy coefficient is compared with the
temperature behavior of paramagnetic susceptibility determining the noticeable
increase of the paramagnetic limiting field in noncentrosymmetric
superconductors. In the last chapter I describe the order parameter and the
symmetry of superconducting state in the itinerant ferromagnet with
orthorhombic symmetry. Finally the Josephson coupling between two adjacent
ferromagnet superconducting domains is discussed.Comment: 15 page
Forming a stable memory representation in the first year of life: Why imitation is more than child's play.
Although 9-month-old infants are capable of retaining temporally ordered information over long delays, this ability is relatively
fragile. It may be possible to facilitate long-term retention by allowing infants to imitate event sequences immediately after
their presentation. The effects of imitation on immediate and delayed recognition and on long-term recall were investigated
using event-related potentials (ERPs) and elicited imitation, respectively. Mnemonic facilitation resulting from the opportunity
to imitate was apparent using both assessments. ERP assessments at immediate and delayed recognition tests suggested that
infants who were allowed to imitate had stronger memory representations of familiar stimuli relative to infants who only viewed
the presentation of the events. In addition, infants who were allowed to imitate evidenced higher levels of ordered recall after 1
month relative to infants who only watched the experimenter’s demonstration. Therefore, imitation proved to have beneficial
effects on explicit memory in 9
1
/
2
-month-olds, providing evidence of its effectiveness as a tool to augment mnemonic capabilities
in infancy
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