117 research outputs found
Beyond substrates : strain engineering of ferroelectric membranes
Strain engineering in perovskite oxides provides for dramatic control over material structure, phase, and properties, but is restricted by the discrete strain states produced by available high-quality substrates. Here, using the ferroelectric BaTiO, production of precisely strain-engineered, substrate-released nanoscale membranes is demonstrated via an epitaxial lift-off process that allows the high crystalline quality of films grown on substrates to be replicated. In turn, fine structural tuning is achieved using interlayer stress in symmetric trilayer oxide-metal/ferroelectric/oxide-metal structures fabricated from the released membranes. In devices integrated on silicon, the interlayer stress provides deterministic control of ordering temperature (from 75 to 425 °C) and releasing the substrate clamping is shown to dramatically impact ferroelectric switching and domain dynamics (including reducing coercive fields to <10 kV cm and improving switching times to <5 ns for a 20 µm diameter capacitor in a 100-nm-thick film). In devices integrated on flexible polymers, enhanced room-temperature dielectric permittivity with large mechanical tunability (a 90% change upon ±0.1% strain application) is demonstrated. This approach paves the way toward the fabrication of ultrafast CMOS-compatible ferroelectric memories and ultrasensitive flexible nanosensor devices, and it may also be leveraged for the stabilization of novel phases and functionalities not achievable via direct epitaxial growth
Control of sand flies with attractive toxic sugar baits (ATSB) and potential impact on non-target organisms in Morocco
International audienceBackground: The persistence and geographical expansion of leishmaniasis is a major public health problem that requires the development of effective integrated vector management strategies for sand fly control. Moreover, these strategies must be economically and environmentally sustainable approaches that can be modified based on the current knowledge of sand fly vector behavior. The efficacy of using attractive toxic sugar baits (ATSB) for sand fly control and the potential impacts of ATSB on non-target organisms in Morocco was investigated. Methods: Sand fly field experiments were conducted in an agricultural area along the flood plain of the Ourika River. Six study sites (600 m x 600 m); three with ``sugar rich'' (with cactus hedges bearing countless ripe fruits) environments and three with ``sugar poor'' (green vegetation only suitable for plant tissue feeding) environments were selected to evaluate ATSB, containing the toxin, dinotefuran. ATSB applications were made either with bait stations or sprayed on non-flowering vegetation. Control sites were established in both sugar rich and sugar poor environments. Field studies evaluating feeding on vegetation treated with attractive (non-toxic) sugar baits (ASB) by non-target arthropods were conducted at both sites with red stained ASB applied to non-flowering vegetation, flowering vegetation, or on bait stations. Results: At both the sites, a single application of ATSB either applied to vegetation or bait stations significantly reduced densities of both female and male sand flies (Phlebotomus papatasi and P. sergenti) for the five-week trial period. Sand fly populations were reduced by 82.8% and 76.9% at sugar poor sites having ATSB applied to vegetation or presented as a bait station, respectively and by 78.7% and 83.2%, respectively at sugar rich sites. The potential impact of ATSB on non-targets, if applied on green non-flowering vegetation and bait stations, was low for all non-target groups as only 1% and 0.7% were stained with non-toxic bait respectively when monitored after 24 hours. Conclusions: The results of this field study demonstrate ATSB effectively controls both female and male sand flies regardless of competing sugar sources. Furthermore, ATSB applied to foliar vegetation and on bait stations has low non-target impact
Sleeping with the Enemy: How Intracellular Pathogens Cope with a Macrophage Lifestyle
Sleeping with the Enemy: How Intracellular Pathogens Cope with a Macrophage Lifestyl
Azimuthal Angle Correlations for Rapidity Separated Hadron Pairs in d+Au Collisions at sqrt(s_NN) = 200 GeV
We report on two-particle azimuthal angle correlations between charged
hadrons at forward/backward (deuteron/gold going direction) rapidity and
charged hadrons at mid-rapidity in deuteron-gold (d+Au) and proton-proton (p+p)
collisions at sqrt(s_NN) = 200 GeV. Jet structures are observed in the
correlations which we quantify in terms of the conditional yield and angular
width of away side partners. The kinematic region studied here samples partons
in the gold nucleus carrying nucleon momentum fraction x~0.1 to x~0.01. Within
this range, we find no x dependence of the jet structure in d+Au collisions.Comment: 330 authors, 6 pages text, 4 figures, no tables. Submitted to Phys.
Rev. Lett. Plain text data tables for the points plotted in figures for this
and previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Centrality dependence of charged hadron production in deuteron+gold and nucleon+gold collisions at sqrt(s_NN)=200 GeV
We present transverse momentum (p_T) spectra of charged hadrons measured in
deuteron-gold and nucleon-gold collisions at \sqrts = 200 GeV for four
centrality classes. Nucleon-gold collisions were selected by tagging events in
which a spectator nucleon was observed in one of two forward rapidity
detectors. The spectra and yields were investigated as a function of the number
of binary nucleon-nucleon collisions, \nu, suffered by deuteron nucleons. A
comparison of charged particle yields to those in p+p collisions show that the
yield per nucleon-nucleon collision saturates with \nu for high momentum
particles. We also present the charged hadron to neutral pion ratios as a
function of p_T.Comment: 330 authors, 15 pages text, 16 figures, 3 tables. Submitted to Phys.
Rev. Lett. v2 has minor changes to reflect revisions during review process.
Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
System Size and Energy Dependence of Jet-Induced Hadron Pair Correlation Shapes in Cu+Cu and Au+Au Collisions at sqrt(s_NN) = 200 and 62.4 GeV
We present azimuthal angle correlations of intermediate transverse momentum
(1-4 GeV/c) hadrons from {dijets} in Cu+Cu and Au+Au collisions at sqrt(s_NN) =
62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is
broadened, non-Gaussian, and peaked away from \Delta\phi=\pi in central and
semi-central collisions in all the systems. The broadening and peak location
are found to depend upon the number of participants in the collision, but not
on the collision energy or beam nuclei. These results are consistent with sound
or shock wave models, but pose challenges to Cherenkov gluon radiation models.Comment: 464 authors from 60 institutions, 6 pages, 3 figures, 2 tables.
Submitted to Physical Review Letters. Plain text data tables for the points
plotted in figures for this and previous PHENIX publications are (or will be)
publicly available at http://www.phenix.bnl.gov/papers.htm
Nuclear Modification Factors for Hadrons At Forward and Backward Rapidities in Deuteron-Gold Collisions at sqrt(s_NN) = 200 GeV
We report on charged hadron production in deuteron-gold reactions at
sqrt(s_NN) = 200 GeV. Our measurements in the deuteron-direction cover 1.4 <
eta < 2.2, referred to as forward rapidity, and in the gold-direction -2.0 <
eta < -1.4, referred to as backward rapidity, and a transverse momentum range
p_T = 0.5-4.0 GeV/c. We compare the relative yields for different deuteron-gold
collision centrality classes. We observe a suppression relative to binary
collision scaling at forward rapidity, sensitive to low momentum fraction (x)
partons in the gold nucleus, and an enhancement at backward rapidity, sensitive
to high momentum fraction partons in the gold nucleus.Comment: 330 authors, 6 pages text, 4 figures, REVTeX4. Published in Physical
Review Letters. Minor changes over previous version in response to referee
and editor comments, plus updating of references. Plain text data tables for
the points plotted in figures for this and previous PHENIX publications are
publicly available at http://www.phenix.bnl.gov/papers.htm
Jet Structure from Dihadron Correlations in d+Au collisions at sqrt(s_NN) = 200 GeV
Dihadron correlations at high transverse momentum in d+Au collisions at
sqrt(s_NN) = 200 GeV at midrapidity are measured by the PHENIX experiment at
the Relativistic Heavy Ion Collider (RHIC). From these correlations we extract
several structural characteristics of jets; the root-mean-squared (RMS)
transverse momentum of fragmenting hadrons with respect to the jet
sqrt(), the mean sine-squared angle between the scattered partons
, and the number of particles produced within the dijet that are
associated with a high-p_T particle (dN/dx_E distributions). We observe that
the fragmentation characteristics of jets in d+Au collisions are very similar
to those in p+p collisions and that there is also little dependence on the
centrality of the d+Au collision. This is consistent with the nuclear medium
having little influence on the fragmentation process. Furthermore, there is no
statistically significant increase in the value of from p+p to
d+Au collisions. This constrains the amount of multiple scattering that partons
undergo in the cold nuclear medium before and after a hard-collision.Comment: 330 authors, 30 pages text, RevTeX4, 42 figures, 20 tables. Submitted
to Physical Review C. Plain text data tables for the points plotted in
figures for this and previous PHENIX publications are (or will be) publicly
available at http://www.phenix.bnl.gov/papers.htm
Transverse-energy distributions at midrapidity in , Au, and AuAu collisions at --200~GeV and implications for particle-production models
Measurements of the midrapidity transverse energy distribution, d\Et/d\eta,
are presented for , Au, and AuAu collisions at
GeV and additionally for AuAu collisions at
and 130 GeV. The d\Et/d\eta distributions are first
compared with the number of nucleon participants , number of
binary collisions , and number of constituent-quark participants
calculated from a Glauber model based on the nuclear geometry. For
AuAu, \mean{d\Et/d\eta}/N_{\rm part} increases with , while
\mean{d\Et/d\eta}/N_{qp} is approximately constant for all three energies.
This indicates that the two component ansatz, , which has been used to represent
distributions, is simply a proxy for , and that the term
does not represent a hard-scattering component in distributions. The
distributions of AuAu and Au are then calculated from
the measured distribution using two models that both reproduce
the AuAu data. However, while the number-of-constituent-quark-participant
model agrees well with the Au data, the additive-quark model does not.Comment: 391 authors, 24 pages, 19 figures, and 15 Tables. Submitted to Phys.
Rev. C. Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are publicly available at
http://www.phenix.bnl.gov/papers.htm
Improved Measurement of Double Helicity Asymmetry in Inclusive Midrapidity pi^0 Production for Polarized p+p Collisions at sqrt(s)=200 GeV
We present an improved measurement of the double helicity asymmetry for pi^0
production in polarized proton-proton scattering at sqrt(s) = 200 GeV employing
the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The
improvements to our previous measurement come from two main factors: Inclusion
of a new data set from the 2004 RHIC run with higher beam polarizations than
the earlier run and a recalibration of the beam polarization measurements,
which resulted in reduced uncertainties and increased beam polarizations. The
results are compared to a Next to Leading Order (NLO) perturbative Quantum
Chromodynamics (pQCD) calculation with a range of polarized gluon
distributions.Comment: 389 authors, 4 pages, 2 tables, 1 figure. Submitted to Phys. Rev. D,
Rapid Communications. Plain text data tables for the points plotted in
figures for this and previous PHENIX publications are (or will be) publicly
available at http://www.phenix.bnl.gov/papers.htm
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