1,567 research outputs found
Sex Attraction in the House Fly, Musca Domestica L.
Author Institution: Entomology Research Division, Agric. Res. Serv., U.S.D.A., Gainesville, Fla.Attraction tests have shown that virgin female house flies attract both virgin males and females but the degree of attraction is relatively small. A tentative hypothesis of chemical sex attraction is suggested. The attraction does not appear to be due to moisture, motion, or sound effects
Decreasing Hospital-Related Complications Using Hourly Nurse Rounding Focused on the 4 P\u27s
This review of literature sought to find the best practice for nurse rounding in hospitals in an effort to reduce hospital-related complication (falls, pressure ulcers) and improve patient satisfaction. Current research shows a growing trend toward hourly rounding centered on addressing basic patient needs, also known as the 4 P\u27s (pain, potty, position and presence). See abstract for more details
School Nutrition Policy: An Evaluation of the Rhode Island Healthier Beverages Policy in Schools
Background. School policies limiting the availability of sweetened beverages are often considered to be effective interventions for improving children\u27s diet and weight-related health. This study was designed to examine the effectiveness of the Rhode Island Healthier Beverage Policy in reducing consumption of unhealthy beverages and in producing changes in children\u27s weight status. Method. Students in 2 public middle schools in Rhode Island completed self-reported measures of dietary intake and were measured for height and weight prior to and 1 year following the implementation of a state-mandated healthier beverage policy. An inventory of beverages available in vending machines after the beverage policy was implemented provided a measure of adherence with the statewide policy. Results. Both surveyed schools demonstrated compliance with the beverage policy (ie, greater than 70% of available beverages complied). Self-reported consumption of sweetened beverages did not change significantly following policy implementation. Neither average BMI percentile for age and gender nor frequency of children in each weight category changed significantly 1 year after the policy was implemented. Conclusions. Although the healthier beverage policy was effectively implemented, it did not result in changes in self-reported sweetened beverage consumption or weight status 1 year later. Additional school policy and individual-level changes appear to be necessary to effect change in weight and dietary outcomes for children. © 2012 The Author(s)
Bis(monoacylglycero)phosphate Forms Stable Small Lamellar Vesicle Structures: Insights into Vesicular Body Formation in Endosomes
AbstractBis(monoacylglycero)phosphate (BMP) is an unusually shaped lipid found in relatively high percentage in the late endosome. Here, we report the characterization of the morphology and molecular organization of dioleoyl-BMP (DOBMP) with dynamic light scattering, transmission electron microscopy, nuclear magnetic resonance (NMR) spectroscopy, and electron paramagnetic resonance spectroscopy. The morphology of hydrated DOBMP dispersions varies with pH and ionic strength, and DOBMP vesicles are significantly smaller in diameter than phosphatidylcholine dispersions. At neutral pH, DOBMP forms highly structured, clustered dispersions 500 nm in size. On the other hand, at acidic pH, spherically shaped vesicles are formed. NMR and spin-labeled electron paramagnetic resonance demonstrate that DOBMP forms a lamellar mesophase with acyl-chain packing similar to that of other unsaturated phospholipids. 31P NMR reveals an orientation of the phosphate group in DOBMP that differs significantly from that of other phospholipids. These macroscopic and microscopic structural characterizations suggest that the biosynthesis of BMP on the inner luminal membrane of maturing endosomes may possibly produce budded vesicles high in BMP content, which form small vesicular structures stabilized by the physical properties of the BMP lipid
Manifolds with small Dirac eigenvalues are nilmanifolds
Consider the class of n-dimensional Riemannian spin manifolds with bounded
sectional curvatures and diameter, and almost non-negative scalar curvature.
Let r=1 if n=2,3 and r=2^{[n/2]-1}+1 if n\geq 4. We show that if the square of
the Dirac operator on such a manifold has small eigenvalues, then the
manifold is diffeomorphic to a nilmanifold and has trivial spin structure.
Equivalently, if M is not a nilmanifold or if M is a nilmanifold with a
non-trivial spin structure, then there exists a uniform lower bound on the r-th
eigenvalue of the square of the Dirac operator. If a manifold with almost
nonnegative scalar curvature has one small Dirac eigenvalue, and if the volume
is not too small, then we show that the metric is close to a Ricci-flat metric
on M with a parallel spinor. In dimension 4 this implies that M is either a
torus or a K3-surface
Searching for New Physics Through AMO Precision Measurements
We briefly review recent experiments in atomic, molecular, and optical
physics using precision measurements to search for physics beyond the Standard
Model. We consider three main categories of experiments: searches for changes
in fundamental constants, measurements of the anomalous magnetic moment of the
electron, and searches for an electric dipole moment of the electron.Comment: Prepared for Comments on AMO Physics at Physica Script
A nonlinear scalar model of extreme mass ratio inspirals in effective field theory II. Scalar perturbations and a master source
The motion of a small compact object (SCO) in a background spacetime is
investigated further in a class of model nonlinear scalar field theories having
a perturbative structure analogous to the General Relativistic description of
extreme mass ratio inspirals (EMRIs). We derive regular expressions for the
scalar perturbations generated by the SCO's motion valid through third order in
, the size of the SCO to the background curvature length scale. Our
expressions are compared to those calculated through second order in
by Rosenthal in [E. Rosenthal, CQG 22, S859 (2005)] and found to agree but our
procedure for regularizing the scalar perturbations is considerably simpler.
Following the Detweiler-Whiting (DW) scheme, we use our regular expressions for
the field and derive the regular self-force corrections through third order. We
find agreement with our previous derivation based on a variational principle of
an effective action for the worldline associated with the SCO thus
demonstrating the internal consistency of our formalism. This also explicitly
demonstrates that the DW decomposition of Green's functions is a valid and
practical method of self force computation at higher orders in perturbation
theory and, as we show in an appendix, at all orders in perturbation theory.
Finally, we identify a master source from which all other physically relevant
quantities are derivable. Knowing the master source perturbatively allows one
to construct the waveform measured by an observer, the regular part of the
field on the worldline, the regular part of the self force, and orbital
quantities such as shifts of the innermost stable circular orbit, etc. The
existence of a master source together with the regularization methods
implemented in this series should be indispensable for derivations of
higher-order gravitational self force corrections.Comment: For Part 1 of this series, see arXiv:1012.4488. 20 pages, 7 figure
Transition Metal Complexes of Dibenzyl Tetraazamacrocycles
Tetraazamacrocycles, cyclic molecules with four nitrogen atoms, have long been known to produce highly stable transition metal complexes. Cross-bridging such molecules with 2-carbon chains has been shown to enhance the stability of these complexes even further, providing enough stability to use the resulting compounds in applications as diverse and demanding as aqueous, green oxidation catalysis all the way to drug molecules injected into humans. Although the stability of these compounds is believed to result from the increased rigidity and topological complexity imparted by the cross-bridge, there is insufficient experimental data to exclude other causes. In this study, standard organic and inorganic synthetic methods were used to produce unbridged dibenzyl tetraazamacrocycle analogues of known cross-bridged tetraazamacrocycles and their transition metal complexes to allow direct comparison of molecules identical except for the cross-bridge. The syntheses of the known tetraazamacrocycles and the novel transition metal complexes were successful with high yields and purity. Initial chemical characterization of the complexes by UV-Visible spectroscopy and cyclic voltammetry shows little difference in electronic properties from bridged versions. Direct comparison studies of the unbridged and bridged compounds’ stabilities remain to be carried out and will shed light on the importance of the cross-bridge to complex robustness
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On-resin N-methylation of cyclic peptides for discovery of orally bioavailable scaffolds.
Backbone N-methylation is common among peptide natural products and has a substantial impact on both the physical properties and the conformational states of cyclic peptides. However, the specific impact of N-methylation on passive membrane diffusion in cyclic peptides has not been investigated systematically. Here we report a method for the selective, on-resin N-methylation of cyclic peptides to generate compounds with drug-like membrane permeability and oral bioavailability. The selectivity and degree of N-methylation of the cyclic peptide was dependent on backbone stereochemistry, suggesting that conformation dictates the regiochemistry of the N-methylation reaction. The permeabilities of the N-methyl variants were corroborated by computational studies on a 1,024-member virtual library of N-methyl cyclic peptides. One of the most permeable compounds, a cyclic hexapeptide (molecular mass = 755 Da) with three N-methyl groups, showed an oral bioavailability of 28% in rat
Radiation reaction and gravitational waves in the effective field theory approach
We compute the contribution to the Lagrangian from the leading order (2.5
post-Newtonian) radiation reaction and the quadrupolar gravitational waves
emitted from a binary system using the effective field theory (EFT) approach of
Goldberger and Rothstein. We use an initial value formulation of the underlying
(quantum) framework to implement retarded boundary conditions and describe
these real-time dissipative processes. We also demonstrate why the usual
scattering formalism of quantum field theory inadequately accounts for these.
The methods discussed here should be useful for deriving real-time quantities
(including radiation reaction forces and gravitational wave emission) and
hereditary terms in the post-Newtonian approximation (including memory, tail
and other causal, history-dependent integrals) within the EFT approach. We also
provide a consistent formulation of the radiation sector in the equivalent
effective field theory approach of Kol and Smolkin.Comment: 23 pages, 8 figure
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