453 research outputs found
Effects of relative phase and interactions on atom-laser outcoupling from a double-well Bose-Einstein condensate: Markovian and non-Markovian dynamics
We investigate aspects of the dynamics of a continuous atom-laser scheme
based on the merging of independently formed atomic condensates. Our
theoretical analysis covers the Markovian as well as the non-Markovian
operational regimes, and is based on a semiclassical (mean-field) two-mode
model. The role of the relative phase between the two condensates and the
effect of interatomic interactions on the evolution of the trapped populations
and the distribution of outcoupled atoms are discussed.Comment: to appear in J. Phys.
Entanglement in the adiabatic limit of a two-atom Tavis-Cummings model
We study the adiabatic limit for the sequential passage of atoms through a
high-Q cavity, in the presence of frequency chirps. Despite the fact that the
adiabatic approximation might be expected to fail, we were able to show that
for proper choice of Stark-pulses this is not the case. Instead, a connection
to the resonant limit is established, where the robust creation of entanglement
is demonstrated. Recent developments in the fabrication of high-Q cavities
allow fidelities for a maximally entangled state up to 97%.Comment: 12 pages, 5 figures, Submitted to Physica Scripta as part of the
Proceedings of the 15th CEWQO 200
Multiple electron trapping in the fragmentation of strongly driven molecules
We present a theoretical quasiclassical study of the formation, during
Coulomb explosion, of two highly excited neutral H atoms (double H) of
strongly driven H. In this process, after the laser field is turned off
each electron occupies a Rydberg state of an H atom. We show that two-electron
effects are important in order to correctly account for double H
formation. We find that the route to forming two H atoms is similar to
pathway B that was identified in Phys. Rev. A {\bf 85} 011402 (R) as one of the
two routes leading to single H formation. However, instead of one
ionization step being "frustrated" as is the case for pathway B, both
ionization steps are "frustrated" in double H formation. Moreover, we
compute the screened nuclear charge that drives the explosion of the nuclei
during double H formation.Comment: 4 pages, 6 figure
Dephasing effects on stimulated Raman adiabatic passage in tripod configurations
We present an analytic description of the effects of dephasing processes on
stimulated Raman adiabatic passage in a tripod quantum system. To this end, we
develop an effective two-level model. Our analysis makes use of the adiabatic
approximation in the weak dephasing regime. An effective master equation for a
two-level system formed by two dark states is derived, where analytic solutions
are obtained by utilizing the Demkov-Kunike model. From these, it is found that
the fidelity for the final coherent superposition state decreases exponentially
for increasing dephasing rates. Depending on the pulse ordering and for
adiabatic evolution the pulse delay can have an inverse effect.Comment: 13 pages; 9 figures; Accepted for publication Physical Review
Familial phenotype differences in PKD1111See Editorial, p. 344.
Familial phenotype differences in PKD1.BackgroundMutations within the PKD1 gene are responsible for the most common and most severe form of autosomal dominant polycystic kidney disease (ADPKD). Although it is known that there is a wide range of disease severity within PKD1 families, it is uncertain whether differences in clinical severity also occur among PKD1 families.MethodsTen large South Wales ADPKD families with at least 12 affected members were included in the study. From affected members, clinical information was obtained, including survival data and the presence of ADPKD-associated complications. Family members who were at risk of having inherited ADPKD but were proven to be non-affected were included as controls. Linkage and haplotype analysis were performed with highly polymorphic microsatellite markers closely linked to the PKD1 gene. Survival data were analyzed by the KaplanâMeier method and the log rank test. Logistic regression analysis was used to test for differences in complication rates between families.ResultsHaplotype analysis revealed that each family had PKD1-linked disease with a unique disease-associated haplotype. Interfamily differences were observed in overall survival (P = 0.0004), renal survival (P = 0.0001), hypertension prevalence (P = 0.013), and hernia (P = 0.048). Individuals with hypertension had significantly worse overall (P = 0.0085) and renal (P = 0.03) survival compared with those without hypertension. No statistically significant differences in the prevalence of hypertension and hernia were observed among controls.ConclusionWe conclude that phenotype differences exist between PKD1 families, which, on the basis of having unique disease-associated haplotypes, are likely to be associated with a heterogeneous range of underlying PKD1 mutations
Non-Markovian dynamics in atom-laser outcoupling from a double-well Bose-Einstein condensate
We investigate the dynamics of a continuous atom laser based on the merging
of independently formed atomic condensates. In a first attempt to understand
the dynamics of the system, we consider two independent elongated Bose-Einstein
condensates which approach each other and focus on intermediate inter-trap
distances so that a two-mode model is well justified. In the framework of a
mean-field theory, we discuss the quasi steady-state population of the traps as
well as the energy distribution of the outcoupled atoms.Comment: 21 pages, 9 figure, to appear in J. Phys.
Geriatric pharmacotherapy : optimisation through integrated approach in the hospital setting
Since older patients are more vulnerable to adverse drug-related events, there is a need to ensure appropriate prescribing in these patients in order to prevent misuse, overuse and underuse of drugs. Different tools and strategies have been developed to reduce inappropriate prescribing; the available measures can be divided into medication assessment tools, and speciïŹc interventions to reduce inappropriate prescribing. Implicit criteria of inappropriate prescribing focus on appropriate dosing, search for drug-drug interactions, and increase adherence. Explicit criteria are consensus-based standards focusing on drugs and diseases and include lists of drugs to avoid in general or lists combining drugs with clinical data. These criteria take into consideration differences between patients, and stand for a medication review, by using a systematic approach. Different types of interventions exist in order to reduce inappropriate prescribing in older patients, such as: educational interventions, computerized decision support systems, pharmacist-based interventions, and geriatric assessment. The effects of these interventions have been studied, sometimes in a multifaceted approach combining different techniques, and all types seem to have positive effects on appropriateness of prescribing. Interdisciplinary teamwork within the integrative pharmaceutical care is important for improving of outcomes and safety of drug therapy. The pharmaceutical care process consists offour steps, which are cyclic for an individual patient. These steps are pharmaceutical anamnesis, medication review, design and follow-up of a pharmaceutical care plan. A standardized approach is necessary for the adequate detection and evaluation of drug-related problems. Furthermore, it is clear that drug therapy should be reviewed in-depth, by having full access to medical records, laboratory values and nursing notes. Although clinical pharmacists perform the pharmaceutical care process to manage the patientâs drug therapy in every day clinical practice, the physician takes the ultimate responsibility for the care of the patient in close collaboration with nurses
A Halomethane thermochemical network from iPEPICO experiments and quantum chemical calculations
Internal energy selected halomethane cations CH3Cl+, CH2Cl2+, CHCl3+, CH3F+, CH2F2+, CHClF2+ and CBrClF2+ were prepared by vacuum ultraviolet photoionization, and their lowest energy dissociation channel studied using imaging photoelectron photoion coincidence spectroscopy (iPEPICO). This channel involves hydrogen atom loss for CH3F+, CH2F2+ and CH3Cl+, chlorine atom loss for CH2Cl2+, CHCl3+ and CHClF2+, and bromine atom loss for CBrClF2+. Accurate 0 K appearance energies, in conjunction with ab initio isodesmic and halogen exchange reaction energies, establish a thermochemical network, which is optimized to update and confirm the enthalpies of formation of the sample molecules and their dissociative photoionization products. The ground electronic states of CHCl3+, CHClF2+ and CBrClF2+ do not confirm to the deep well assumption, and the experimental breakdown curve deviates from the deep well model at low energies. Breakdown curve analysis of such shallow well systems supplies a satisfactorily succinct route to the adiabatic ionization energy of the parent molecule, particularly if the threshold photoelectron spectrum is not resolved and a purely computational route is unfeasible. The ionization energies have been found to be 11.47 ± 0.01 eV, 12.30 ± 0.02 eV and 11.23 ± 0.03 eV for CHCl3, CHClF2 and CBrClF2, respectively. The updated 0 K enthalpies of formation, âfHo0K(g) for the ions CH2F+, CHF2+, CHCl2+, CCl3+, CCl2F+ and CClF2+ have been derived to be 844.4 ± 2.1, 601.6 ± 2.7, 890.3 ± 2.2, 849.8 ± 3.2, 701.2 ± 3.3 and 552.2 ± 3.4 kJ molâ1, respectively. The âfHo0K(g) values for the neutrals CCl4, CBrClF2, CClF3, CCl2F2 and CCl3F and have been determined to be â94.0 ± 3.2, â446.6 ± 2.7, â702.1 ± 3.5, â487.8 ± 3.4 and â285.2 ± 3.2 kJ molâ1, respectively
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