2,203 research outputs found
A Mott-like State of Molecules
We prepare a quantum state where each site of an optical lattice is occupied
by exactly one molecule. This is the same quantum state as in a Mott insulator
of molecules in the limit of negligible tunneling. Unlike previous Mott
insulators, our system consists of molecules which can collide inelastically.
In the absence of the optical lattice these collisions would lead to fast loss
of the molecules from the sample. To prepare the state, we start from a Mott
insulator of atomic 87Rb with a central region, where each lattice site is
occupied by exactly two atoms. We then associate molecules using a Feshbach
resonance. Remaining atoms can be removed using blast light. Our method does
not rely on the molecule-molecule interaction properties and is therefore
applicable to many systems.Comment: Proceedings of the 20th International Conference on Atomic Physics
(ICAP 2006), edited by C. Roos, H. Haffner, and R. Blatt, AIP Conference
Proceedings, Melville, 2006, Vol. 869, pp. 278-28
Auger Electrons from Argon with Energies 150-210 eV Produced by H\u3csup\u3e+\u3c/sup\u3e and H\u3csub\u3e2\u3c/sub\u3e\u3csup\u3e\u3c/sup\u3e Impacts
Secondary electrons in the energy range 150-210 eV produced by 125-300-keV H+ and H2+ impacts on argon gas are measured as a function of their energy and angle of emission. Discrete line spectra are due to Auger transitions from L2 and L3 vacancy states as well as satellite transitions from multivacancy states. The widths, energies, and branching ratios of the L2 and L3 vacancy states are presented. Widths of these states are appreciably greater than those obtained with electron impact excitation. This can be attributed to the recoil velocities of the target atom and to the presence of the proton in the vicinity of the emitting atom. The angular distribution of Auger electrons is found to be nearly isotropic, in marked contrast to electrons in the continum spectrum. The cross sections for the production of L2,3 and L3 vacancy states are determined as a function of impact energy
Predictors of family communication of one’s organ donation intention in Switzerland
OBJECTIVES: Family members continue to play a prominent role in decisions to donate organs at the time of death. Prior knowledge of the deceased's intention to donate was identified as an important influential factor in the donation decision-making process. This study examined what factors lead to family communication of a person's wish regarding organ donation. METHODS: A population-based survey was used to identify the prevalence of people who had informed family members of their intention to donate. Associated factors were evaluated using bivariate and multivariate analyses. RESULTS: Multivariate analysis revealed that communication to a family member of the intention to donate organs was more likely if the respondent had a signed donor card (OR = 10.23, CI = 5.25-19.93), had a family discussion on organ donation or transplantation (OR = 7.12, CI = 4.91-10.34), had a partner and knew his or her attitude to organ donation (OR = 5.76, CI = 4.20-7.90), had previously personally had a good look at the issue of organ donation (OR = 2.59, CI = 1.79-3.75), was rather younger (OR = 0.98, CI = 0.97-0.99), was of Swiss nationality (OR = 2.21, CI = 1.25-3.91), felt that he or she was sufficiently informed (OR = 2.10, CI = 1.50-2.94), had the information necessary to come to an appropriate decision on organ donation and-although this relation may be weaker-were (rather) willing to become an organ donor after death (OR = 1.41, CI = 1.01-1.97). CONCLUSIONS: Our findings highlight the need for public education and community campaigns to promote the need to share with others, the intention to donate and to increase people's knowledge on this issue
Gladiolus varieties in floriculture trial gardens at Iowa State College
One of the few gladiolus trial gardens in the United States is located at Ames, Iowa. This project was established in 1929 by the Iowa Gladiolus Society and the Department of Horticulture at Iowa State College. It has enjoyed the active cooperation of gladiolus breeders and commercial growers. The purpose of this garden is to make a comparative study of new and important varieties of gladioli to determine their commercial value and general adaptability. The value of this trial garden from a demonstration point of view alone can hardly be overestimated. Thousands of plant lovers visit the garden annually to inspect and study the blooms of the named varieties of this popular flower. The entire stock now under observation has been acquired by voluntary contribution of gladiolus growers and originators. These donated corms are held for test and demonstration only; none are for sale or otherwise distributed. Complete records are taken on season, racial character, vigor, habits of growth, color, markings and commercial value. This information is available to all who desire it, and it is the purpose of this bulletin to present tabulated results of performance records taken on the outstanding varieties under trial over a one-year and in some cases a two-year period. There are 253 varieties in this special list
Auger Electrons from Argon with Energies 150-210 eV Produced by H\u3csup\u3e+\u3c/sup\u3e and H\u3csub\u3e2\u3c/sub\u3e\u3csup\u3e\u3c/sup\u3e Impacts
Secondary electrons in the energy range 150-210 eV produced by 125-300-keV H+ and H2+ impacts on argon gas are measured as a function of their energy and angle of emission. Discrete line spectra are due to Auger transitions from L2 and L3 vacancy states as well as satellite transitions from multivacancy states. The widths, energies, and branching ratios of the L2 and L3 vacancy states are presented. Widths of these states are appreciably greater than those obtained with electron impact excitation. This can be attributed to the recoil velocities of the target atom and to the presence of the proton in the vicinity of the emitting atom. The angular distribution of Auger electrons is found to be nearly isotropic, in marked contrast to electrons in the continum spectrum. The cross sections for the production of L2,3 and L3 vacancy states are determined as a function of impact energy
Thermal contact resistance between two nanoparticles
We compute the thermal conductance between two nanoparticles in contact based
on the Molecular Dynamics technique. The contact is generated by letting both
particles stick together under van der Waals attractions. The thermal
conductance is derived from the fluctuation-dissipation theorem and the time
fluctuations of the exchanged power. We show that the conductance is
proportional to the atoms involved in the thermal interaction. In the case of
silica, the atomic contribution to the thermal conductance is in the range of
0.5 to 3 nW.K-1. This result fits to theoretical predictions based on
characteristic times of the temperature fluctuation. The order of magnitude of
the contact conductance is 1 \mu W.K-1 when the cross section ranges from 1 to
10nm2
On Calculation of Thermal Conductivity from Einstein Relation in Equilibrium MD
In equilibrium molecular dynamics, Einstein relation can be used to calculate
the thermal conductivity. This method is equivalent to Green-Kubo relation and
it does not require a derivation of an analytical form for the heat current.
However, it is not commonly used as Green-Kubo relationship. Its wide use is
hindered by the lack of a proper definition for integrated heat current (energy
moment) under periodic boundary conditions. In this paper, we developed an
appropriate definition for integrated heat current to calculate thermal
conductivity of solids under periodic conditions. We applied this method to
solid argon and silicon based systems; compared and contrasted with the
Green-Kubo approach.Comment: We updated this manuscript from second version by changing the title
and abstract. This paper is submitted to J. Chem. Phy
Atom-molecule Rabi oscillations in a Mott insulator
We observe large-amplitude Rabi oscillations between an atomic and a
molecular state near a Feshbach resonance. The experiment uses 87Rb in an
optical lattice and a Feshbach resonance near 414 G. The frequency and
amplitude of the oscillations depend on magnetic field in a way that is well
described by a two-level model. The observed density dependence of the
oscillation frequency agrees with the theoretical expectation. We confirmed
that the state produced after a half-cycle contains exactly one molecule at
each lattice site. In addition, we show that for energies in a gap of the
lattice band structure, the molecules cannot dissociate
Optical diode based on the chirality of guided photons
Photons are nonchiral particles: their handedness can be both left and right.
However, when light is transversely confined, it can locally exhibit a
transverse spin whose orientation is fixed by the propagation direction of the
photons. Confined photons thus have chiral character. Here, we employ this to
demonstrate nonreciprocal transmission of light at the single-photon level
through a silica nanofibre in two experimental schemes. We either use an
ensemble of spin-polarised atoms that is weakly coupled to the nanofibre-guided
mode or a single spin-polarised atom strongly coupled to the nanofibre via a
whispering-gallery-mode resonator. We simultaneously achieve high optical
isolation and high forward transmission. Both are controlled by the internal
atomic state. The resulting optical diode is the first example of a new class
of nonreciprocal nanophotonic devices which exploit the chirality of confined
photons and which are, in principle, suitable for quantum information
processing and future quantum optical networks
- …