Towards an Atom Laser: Cold Atoms in a Long High-gradient Magnetic Guide.

The propagation of an atomic beam through a 1.7 m long magnetic guide with magnetic field gradient of up to 2.7 kGauss/cm has been demonstrated. The guide is side-loaded with an atomic beam from a Pyramidal MOT Low-velocity Intense Source. The atomic beam observed at the end of the guide has a flux of 3×10e7 atoms/s with a velocity of 1.2 m/s, a transverse temperature of 420±40 μK and a longitudinal temperature of 1 mK. The guided atomic beam was mode-filtered by selective removal of high-energy atoms using radio-frequency coupling to magnetically untrapped states. We found that the phase-space density of the atomic beam was very low for evaporative cooling to be functional. An imaging technique was developed to characterize the guided atomic flow in the presence of a high magnetic field gradient. This technique utilizes the open-channel transition to obtain nearly constant photon yield per atom independent of the location of the atom in the guide, providing a mapping of the fluorescence images to the atomic-density profiles. This technique was theoretically studied using Quantum Monte-Carlo Simulations and validated. A Zeeman slower was constructed and characterized to be used as the primary source of atoms to the magnetic guide. The Zeeman slower output atomic beam has a flux of 3×10e11 atoms/s at a velocity of 40 m/s. We have designed a new injection scheme to transfer atoms from the Zeeman slower to the magnetic guide efficiently. The details of a new method to evaporatively cool atoms in the magnetic guide using surface adsorption are described. Finally, a new guide geometry based on a spiral structure is discussed.Ph.D.Applied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/60753/1/rmhaskar_1.pd

JAMA Published Fewer Industry-Funded Studies after Introducing a Requirement for Independent Statistical Analysis

BACKGROUND: JAMA introduced a requirement for independent statistical analysis for industry-funded trials in July 2005. We wanted to see whether this policy affected the number of industry-funded trials published by JAMA. METHODS AND FINDINGS: We undertook a retrospective, before-and-after study of published papers. Two investigators independently extracted data from all issues of JAMA published between 1 July 2002 and 30 June 2008 (i.e., three years before and after the policy). They were not blinded to publication date. The randomized controlled trials (RCTs) were classified as industry funded (IF), joint industry/non-commercial funding (J), industry supported (IS) (when manufacturers provided materials only), non-commercial (N) or funding not stated (NS). Findings were compared and discrepancies resolved by discussion or further analysis of the reports. RCTs published in The Lancet and NEJM over the same period were used as a control group. Between July 2002 and July 2008, JAMA published 1,314 papers, of which 311 were RCTs. The number of industry studies (IF, J or IS) fell significantly after the policy (p = 0.02) especially for categories J and IS. However, over the same period, the number of industry studies rose in both The Lancet and NEJM. CONCLUSIONS: After the requirement for independent statistical analysis for industry-funded studies, JAMA published significantly fewer RCTs and significantly fewer industry-funded RCTs. This pattern was not seen in the control journals. This suggests the JAMA policy affected the number of submissions, the acceptance rate, or both. Without analysing the submissions, we cannot check these hypotheses but, assuming the number of published papers is related to the number submitted, our findings suggest that JAMA's policy may have resulted in a significant reduction in the number of industry-sponsored trials it received and published

Concordance between decision analysis and matching systematic review of randomized controlled trials in assessment of treatment comparisons: a systematic review

BACKGROUND: Systematic review (SR) of randomized controlled trials (RCT) is the gold standard for informing treatment choice. Decision analyses (DA) also play an important role in informing health care decisions. It is unknown how often the results of DA and matching SR of RCTs are in concordance. We assessed whether the results of DA are in concordance with SR of RCTs matched on patient population, intervention, control, and outcomes. METHODS: We searched PubMed up to 2008 for DAs comparing at least two interventions followed by matching SRs of RCTs. Data were extracted on patient population, intervention, control, and outcomes from DAs and matching SRs of RCTs. Data extraction from DAs was done by one reviewer and from SR of RCTs by two independent reviewers. RESULTS: We identified 28 DAs representing 37 comparisons for which we found matching SR of RCTs. Results of the DAs and SRs of RCTs were in concordance in 73% (27/37) of cases. The sensitivity analyses conducted in either DA or SR of RCTs did not impact the concordance. Use of single (4/37) versus multiple data source (33/37) in design of DA model was statistically significantly associated with concordance between DA and SR of RCTs. CONCLUSIONS: Our findings illustrate the high concordance of current DA models compared with SR of RCTs. It is shown previously that there is 50% concordance between DA and matching single RCT. Our study showing the concordance of 73% between DA and matching SR of RCTs underlines the importance of totality of evidence (i.e. SR of RCTs) in the design of DA models and in general medical decision-making