2,861 research outputs found
Observation of Feshbach resonances between two different atomic species
We have observed three Feshbach resonances in collisions between lithium-6
and sodium-23 atoms. The resonances were identified as narrow loss features
when the magnetic field was varied. The molecular states causing these
resonances have been identified, and additional lithium-sodium resonances are
predicted. These resonances will allow the study of degenerate Bose-Fermi
mixtures with adjustable interactions, and could be used to generate ultracold
heteronuclear molecules
Observation of Bose-Einstein Condensation of Molecules
We have observed Bose-Einstein condensation of molecules. When a spin mixture
of fermionic Li-6 atoms was evaporatively cooled in an optical dipole trap near
a Feshbach resonance, the atomic gas was converted into Li_2 molecules. Below
600 nK, a Bose-Einstein condensate of up to 900,000 molecules was identified by
the sudden onset of a bimodal density distribution. This condensate realizes
the limit of tightly bound fermion pairs in the crossover between BCS
superfluidity and Bose-Einstein condensation.Comment: 4 pages, 3 figure
Formation Time of a Fermion Pair Condensate
The formation time of a condensate of fermionic atom pairs close to a
Feshbach resonance was studied. This was done using a phase-shift method in
which the delayed response of the many-body system to a modulation of the
interaction strength was recorded. The observable was the fraction of condensed
molecules in the cloud after a rapid magnetic field ramp across the Feshbach
resonance. The measured response time was slow compared to the rapid ramp,
which provides final proof that the molecular condensates reflect the presence
of fermion pair condensates before the ramp.Comment: 5 pages, 4 figure
How can we improve teaching of ECG interpretation skills? Findings from a prospective randomised trial.
BACKGROUND: There is an ongoing debate on how ECG interpretation should be taught during undergraduate medical training. This study addressed the impact of teaching format, examination consequences and student motivation on skills retention. METHODS: A total of 493 fourth-year medical students participated in a six-group, partially randomised trial. Students received three levels of teaching intensity: self-directed learning (2 groups), lectures (2 groups) or small-group peer-teaching (2 groups). On each level of teaching intensity, end-of-course written examinations (ECG exit exam) were summative in one group and formative in the other. Learning outcome was assessed in a retention test two months later. RESULTS: Retention test scores were predicted by summative assessments (adjusted beta 4.08; 95% CI 1.39-6.78) but not by the type of teaching. Overall performance levels and motivation did not predict performance decrease or skills retention. CONCLUSIONS: Summative assessments increase medium-term retention of ECG interpretation skills, irrespective of instructional format
Significant increase in factual knowledge with web-assisted problem-based learning as part of an undergraduate cardio-respiratory curriculum
In recent years, increasing attention has been paid to web-based learning although the advantages of computer-aided instruction over traditional teaching formats still need to be confirmed. This study examined whether participation in an online module on the differential diagnosis of dyspnoea impacts on student performance in a multiple choice examination of factual knowledge in cardiology and pneumology. A virtual problem-based learning environment for medical students supervised by postgraduate teachers was created. Seventy-four out of 183 fourth-year medical students volunteered to use the online module while attending a 6-week cardio-respiratory curriculum in summer 2007. Of these, 40 were randomly selected to be included (intervention group); the remaining 34 served as an internal control group. Analysis of all written exams taken during the preceding term showed that both groups were comparable (86.4 ± 1.1 vs. 85.9 ± 1.1%; p = 0.751). Students in the intervention group scored significantly higher in the final course assessment than students allocated to the control group (84.8 ± 1.3 vs. 79.5 ± 1.4%; p = 0.006; effect size 0.67). Thus, additional problem-based learning with an online module as part of an undergraduate cardio-respiratory curriculum lead to higher students’ scores in an exam testing factual knowledge. Whether using this teaching format increases overall student motivation to engage in the learning process needs to be further investigated
Search for proton decay in the Frejus experiment
The status of the Frejus experiment and the preliminary results obtained in the search for nucleon decay are discussed. A modular, fine grain tracking calorimeter was installed in the Frejus laboratory in the period extending from October 1983 to May 1985. The 3300 cubic meter underground laboratory, located in the center of the Frejus tunnel in the Alps, is covered in the vertical direction by 1600 m of rocks (4400 m w.e.). The average number of atmospheric muons in the lab is 4.2 square meters per day. The 912 ton detector is made of 114 modules, each one including eight flash chamber and one Geiger vertical planes of (6 x 6) square meters dimensions. The flash chamber (and Geiger) planes are alternatively crossed to provide a 90 deg. stereo reconstruction. No candidate for the nucleon decay into charged lepton is found in the first sample of events
Structured Smoking Cessation Training for Medical Students: a prospective study
Introduction: Physician adherence to guideline recommendations regarding the provision of counseling and support for smokers willing to quit is low. A lack of training during undergraduate medical education has been identified as a potential cause. This prospective intervention study evaluated a novel teaching module for medical students.
Methods: As part of a 6-week cardiovascular course, 125 fourth-year undergraduate medical students received a multimodal and interactive teaching module on smoking cessation, including online learning material, lectures, seminars, and practical skills training. Short- and medium-term effects on knowledge, skills, attitudes, and self-reported practice were measured using written examinations and an objective structured clinical examination at the end of the module and 6 months later. Results were compared to data obtained from a historical control cohort (n = 70) unexposed to the intervention.
Results: At the 6-month follow-up, scores in the knowledge test were significantly higher in the intervention than the control group (61.1% vs. 51.7%; p < .001). A similar pattern was observed in the objective structured clinical examination (71.5% vs. 60.5%; p < .001). More students in the intervention than control group agreed that smoking was a chronic disease (83.1% vs. 68.1%; p = .045). The control group was more likely to report recording smoking status (p = .018), but no group difference was detected regarding the report of advising to quit (p = .154).
Conclusions: A novel teaching module for undergraduate medical students produced a sustained learning outcome in terms of knowledge, skills, and attitudes but not self-reported practice.
Implications: Studies across the world have identified considerable knowledge gaps and deficits in practical training with regard to smoking cessation counseling in undergraduate medical students. This paper describes a teaching intervention informed by current recommendations for the design of educational activities aimed at enabling medical students to deliver adequate behavior change counseling. The teaching module was tailored to the needs of a specific healthcare system. Given its effectiveness as demonstrated in this prospective study, a rollout of this intervention in medical schools might have the potential to substantially improve medical students’ knowledge, skills, and attitudes in relation to smoking cessation counseling
Condensation of Pairs of Fermionic Atoms Near a Feshbach Resonance
We have observed Bose-Einstein condensation of pairs of fermionic atoms in an
ultracold ^6Li gas at magnetic fields above a Feshbach resonance, where no
stable ^6Li_2 molecules would exist in vacuum. We accurately determined the
position of the resonance to be 822+-3 G. Molecular Bose-Einstein condensates
were detected after a fast magnetic field ramp, which transferred pairs of
atoms at close distances into bound molecules. Condensate fractions as high as
80% were obtained. The large condensate fractions are interpreted in terms of
pre-existing molecules which are quasi-stable even above the two-body Feshbach
resonance due to the presence of the degenerate Fermi gas.Comment: submitted to PRL. v3: clarifying revisions, added referenc
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