1,218 research outputs found
Spatial learning and memory in the tortoise (Geochelone carbonaria)
A single tortoise (Geochelone carbonaria) was trained in an eight-arm radial maze, with the apparatus and general procedures modeled on those used to demonstrate spatial learning in rats. The tortoise learned to perform reliably above chance, preferentially choosing baited arms, rather than returning to arms previously visited on a trial. Test sessions that examined control by olfactory cues revealed that they did not affect performance. No systematic, stereotyped response patterns were evident. In spite of differences in brain structure, the tortoise showed spatial learning abilities comparable to those observed in mammals
Weak force detection using a double Bose-Einstein condensate
A Bose-Einstein condensate may be used to make precise measurements of weak
forces, utilizing the macroscopic occupation of a single quantum state. We
present a scheme which uses a condensate in a double well potential to do this.
The required initial state of the condensate is discussed, and the limitations
on the sensitivity due to atom collisions and external coupling are analyzed.Comment: 12 pages, 2 figures, Eq.(41) has been correcte
Friction force on a vortex due to the scattering of superfluid excitations in helium II
The longitudinal friction acting on a vortex line in superfluid He is
investigated within a simple model based on the analogy between such vortex
dynamics and that of the quantal Brownian motion of a charged point particle in
a uniform magnetic field. The scattering of superfluid quasiparticle
excitations by the vortex stems from a translationally invariant interaction
potential which, expanded to first order in the vortex velocity operator, gives
rise to vortex transitions between nearest Landau levels. The corresponding
friction coefficient is shown to be, in the limit of elastic scattering
(vanishing cyclotron frequency), equivalent to that arising from the Iordanskii
formula. Proposing a simple functional form for the scattering amplitude, with
only one adjustable parameter whose value is set in order to get agreement to
the Iordanskii result for phonons, an excellent agreement is also found with
the values derived from experimental data up to temperatures about 1.5 K.
Finite values of the cyclotron frequency arising from recent theories are shown
to yield similar results. The incidence of vortex-induced quasiparticle
transitions on the friction process is estimated to be, in the roton dominated
regime, about 50 % of the value of the friction coefficient, 8 % of which
corresponds to roton-phonon transitions and 42 % to roton
ones.Comment: 15 pages, 4 figures; typos corrected, to be published in PR
Anomalies on orbifolds with gauge symmetry breaking
We embed two 4D chiral multiplets of opposite representations in the 5D N=2
gauge theory compactified on an orbifold .
There are two types of orbifold boundary conditions in the extra dimension to
obtain the 4D N=1 gauge theory from the bulk: in
Type I, one has the bulk gauge group at and the unbroken gauge group at
while in Type II, one has the unbroken gauge group at both fixed
points. In both types of orbifold boundary conditions, we consider the zero
mode(s) as coming from a bulk -plet and brane fields at the fixed
point(s) with the unbroken gauge group. We check the consistency of this
embedding of fields by the localized anomalies and the localized FI terms. We
show that the localized anomalies in Type I are cancelled exactly by the
introduction of a bulk Chern-Simons term. On the other hand, in some class of
Type II, the Chern-Simons term is not enough to cancel all localized anomalies
even if they are globally vanishing. We also find that for the consistent
embedding of brane fields, there appear only the localized log FI terms at the
fixed point(s) with a U(1) factor.Comment: LaTeX file of 19 pages with no figure, published versio
Interventions to prevent obesity in school-aged children 6-18 years: An update of a Cochrane systematic review and meta-analysis including studies from 2015–2021
Background Childhood obesity remains a global public health priority due to the enormous burden it generates. Recent surveillance data suggests there has been a sharp increase in the prevalence of childhood obesity during the COVID-19 pandemic. The Cochrane review of childhood obesity prevention interventions (0–18 years) updated to 2015 is the most rigorous and comprehensive review of randomised controlled trials (RCTs) on this topic. A burgeoning number of high quality studies have been published since that are yet to be synthesised. Methods An update of the Cochrane systematic review was conducted to include RCT studies in school-aged children (6-18 years) published to 30 June 2021 that assessed effectiveness on child weight (PROSPERO registration: CRD42020218928). Available cost-effectiveness and adverse effect data were extracted. Intervention effects on body mass index (BMI) were synthesised in random effects meta-analyses by setting (school, after-school program, community, home), and meta-regression examined the association of study characteristics with intervention effect. Findings Meta-analysis of 140 of 195 included studies (183,063 participants) found a very small positive effect on body mass index for school-based studies (SMD –0·03, 95%CI –0·06,–0·01; trials = 93; participants = 131,443; moderate certainty evidence) but not after-school programs, community or home-based studies. Subgroup analysis by age (6–12 years; 13–18 years) found no differential effects in any setting. Meta-regression found no associations between study characteristics (including setting, income level) and intervention effect. Ten of 53 studies assessing adverse effects reported presence of an adverse event. Insufficient data was available to draw conclusions on cost-effectiveness. Interpretation This updated synthesis of obesity prevention interventions for children aged 6–18 years, found a small beneficial impact on child BMI for school-based obesity prevention interventions. A more comprehensive assessment of interventions is required to identify mechanisms of effective interventions to inform future obesity prevention public health policy, which may be particularly salient in for COVID-19 recovery planning. Funding This research was funded by the National Health and Medical Research Council (NHMRC), Australia (Application No APP1153479)
Identification of stingless bees (Hymenoptera: Apidae) in Kenya using Morphometrics and DNA barcoding
Stingless bees are important pollinators of wild plants and crops. The identity of stingless bee species in Africa has not been fully documented. The present study explored the utility of morphometrics and DNA barcoding for identification of African stingless bee populations, and to further employ these tools to identify potential cryptic variation within species. Stingless bee samples were collected from three ecological zones, namely Kakamega Forest, Mwingi and Arabuko-Sokoke Forest, which are geographically distant and cover high, medium and low altitudes, respectively. Forewing and hind leg morphometric characters were measured to determine the extent of morphological variation between the populations. DNA barcodes were generated from the mitochondrial cytochrome c-oxidase I (COI) gene. Principal Component Analysis (PCA) on the morphometric measurements separated the bee samples into three clusters: (1) Meliponula bocandei; (2) Meliponula lendliana + Plebeina hildebrandti; (3) Dactylurina schmidti + Meliponula ferruginea black + Meliponula ferruginea reddish brown, but Canonical Variate Analysis (CVA) separated all the species except the two morphospecies (M. ferruginea reddish brown and black). The analysis of the COI sequences showed that DNA barcoding can be used to identify all the species studied and revealed remarkable genetic distance (7.3%) between the two M. ferruginea morphs. This is the first genetic evidence that M. ferruginea black and M. ferruginea reddish brown are separate species
Search for Solar Axions Produced in the Reaction
A search for the axioelectric absorption of 5.5-MeV solar axions produced in
the reaction was performed with
two BGO detectors placed inside a low-background setup. A model independent
limit on axion-photon and axion-nucleon couplings was obtained: . Constraints on the axion-electron
coupling constant were obtained for axions with masses in the MeV
range: . The solar positron flux from
decay was determined for axions with masses . Using the existing experimental data on the interplanetary positron
flux, a new constraint on the axion-electron coupling constant for axions with
masses in the MeV range was obtained: .Comment: 6 pages, 5 figure
Prolonged enoxaparin therapy compared with standard-of-care antithrombotic therapy in opiate-treated patients undergoing primary percutaneous coronary intervention
A novel enoxaparin regimen consisting of intra-arterial bolus (0.75 mg/kg) followed by intravenous infusion (0.75 mg/kg/6 hours) has been developed as a possible solution to the delayed absorption of oral P2Y12 inhibitors in opiate-treated ST-elevation myocardial infarction (STEMI) patients undergoing primary angioplasty. We aimed to study the feasibility of this regimen as an alternative to standard-of-care treatment (SOC) with unfractionated heparin ± glycoprotein IIb/IIIa antagonist (GPI). One hundred opiate-treated patients presenting with STEMI and accepted for primary angioplasty were randomized (1:1) to either enoxaparin or SOC. Fifty patients were allocated enoxaparin (median age 61, 40% females) and 49 allocated SOC (median age 62, 22% females). One developed stroke before angiography and was withdrawn. One SOC patient had a gastrointestinal bleed resulting in 1 g drop in hemoglobin and early cessation of GPI infusion. Two enoxaparin patients had transient minor bleeding: one transient gingival bleed and one episode of coffee ground vomit with no hemoglobin drop or hemodynamic instability. Two SOC and no enoxaparin group patients had acute stent thrombosis. These preliminary data support further study of this novel 6-hour enoxaparin regimen in opiate-treated PPCI patients
Origami World
We paste together patches of to find solutions which describe two
4-branes intersecting on a 3-brane with non-zero tension. We construct
explicitly brane arrays with Minkowski, de Sitter and Anti-de Sitter geometries
intrinsic to the 3-brane, and describe how to generalize these solutions to the
case of , , where -branes intersect on a 3-brane. The
Minkowski and de Sitter solutions localize gravity to the intersection, leading
to 4D Newtonian gravity at large distances. We show this explicitly in the case
of Minkowski origami by finding the zero-mode graviton, and computing the
couplings of the bulk gravitons to the matter on the intersection. In de Sitter
case, this follows from the finiteness of the bulk volume. The effective 4D
Planck scale depends on the square of the fundamental 6D Planck scale, the
radius and the angles between the 4-branes and the radial
direction, and for the Minkowski origami it is . If this may account for the Planck-electroweak hierarchy even if , with a possibility for sub-millimeter corrections to the
Newton's law. We comment on the early universe cosmology of such models.Comment: plain LaTeX, 23 pages + 2 .eps figure
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