332 research outputs found
Design of Strongly Modulating Pulses to Implement Precise Effective Hamiltonians for Quantum Information Processing
We describe a method for improving coherent control through the use of
detailed knowledge of the system's Hamiltonian. Precise unitary transformations
were obtained by strongly modulating the system's dynamics to average out
unwanted evolution. With the aid of numerical search methods, pulsed
irradiation schemes are obtained that perform accurate, arbitrary, selective
gates on multi-qubit systems. Compared to low power selective pulses, which
cannot average out all unwanted evolution, these pulses are substantially
shorter in time, thereby reducing the effects of relaxation. Liquid-state NMR
techniques on homonuclear spin systems are used to demonstrate the accuracy of
these gates both in simulation and experiment. Simulations of the coherent
evolution of a 3-qubit system show that the control sequences faithfully
implement the unitary operations, typically yielding gate fidelities on the
order of 0.999 and, for some sequences, up to 0.9997. The experimentally
determined density matrices resulting from the application of different control
sequences on a 3-spin system have overlaps of up to 0.99 with the expected
states, confirming the quality of the experimental implementation.Comment: RevTeX3, 11 pages including 2 tables and 5 figures; Journal of
Chemical Physics, in pres
Experimental ionization of atomic hydrogen with few-cycle pulses
We present the first experimental data on strong-field ionization of atomic
hydrogen by few-cycle laser pulses. We obtain quantitative agreement at the 10%
level between the data and an {\it ab initio} simulation over a wide range of
laser intensities and electron energies
Diffuse versus square-well confining potentials in modelling @C atoms
Attention: this version- of the manuscript differs from its previously
uploaded version- (arXiv:1112.6158v1) and subsequently published in 2012 J.
Phys. B \textbf{45} 105102 only by a removed typo in Eq.(2) of version-;
there was the erroneous factor "2" in both terms in the right-hand-side of the
Eq.(2) of version-. Now that the typo is removed, Eq.(2) is correct.
A perceived advantage for the replacement of a discontinuous square-well
pseudo-potential, which is often used by various researchers as an
approximation to the actual C cage potential in calculations of
endohedral atoms @C, by a more realistic diffuse potential is
explored. The photoionization of endohedral H@C and Xe@C is
chosen as the case study. The diffuse potential is modelled by a combination of
two Woods-Saxon potentials. It is demonstrated that photoionization spectra of
@C atoms are largely insensitive to the degree of diffuseness
of the potential borders, in a reasonably broad range of 's.
Alternatively, these spectra are found to be insensitive to discontinuity of
the square-well potential either. Both potentials result in practically
identical calculated spectra. New numerical values for the set of square-well
parameters, which lead to a better agreement between experimental and
theoretical data for @C spectra, are recommended for future studies.Comment: 11 pages, 4 figure
Student Evaluation of Faculty Physicians: Gender Differences in Teaching Evaluations
Purpose: To investigate whether there is a difference in medical student teaching evaluations for male and female clinical physician faculty. Methods: The authors examined all teaching evaluations completed by clinical students at one North American medical school in the surgery, obstetrics and gynecology, pediatrics, and internal medicine clinical rotations from 2008 to 2012. The authors focused on how students rated physician faculty on their ?overall quality of teaching? using a 5-point response scale (1?=?Poor to 5?=?Excellent). Linear mixed-effects models provided estimated mean differences in evaluation outcomes by faculty gender. Results: There were 14,107 teaching evaluations of 965 physician faculty. Of these evaluations, 7688 (54%) were for male physician faculty and 6419 (46%) were for female physician faculty. Female physicians received significantly lower mean evaluation scores in all four rotations. The discrepancy was largest in the surgery rotation (males?=?4.23, females?=?4.01, p?=?0.003). Pediatrics showed the next greatest difference (males?=?4.44, females?=?4.29, p?=?0.009), followed by obstetrics and gynecology (males?=?4.38, females?=?4.26, p?=?0.026), and internal medicine (males?=?4.35, females?=?4.27, p?=?0.043). Conclusions: Female physicians received lower teaching evaluations in all four core clinical rotations. This comprehensive examination adds to the medical literature by illuminating subtle differences in evaluations based on physician gender, and provides further evidence of disparities for women in academic medicine.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140140/1/jwh.2015.5475.pd
Ready or Not, Here They Come: Acting Internsâ Experience and Perceived Competency Performing Basic Medical Procedures
OBJECTIVE: To assess acting internsâ (AIâs) experience with and perceived level of competency performing 6 basic medical procedures. DESIGN: Fourth-year medical students at the University of Cincinnati (UCCOM) are required to complete 2 AI rotations in Internal Medicine. All AIs in 2003â2004 (nâ=â150) and 2004â2005 (nâ=â151) were asked to complete a survey about whether during each of their rotations they had performed and felt competent performing the following procedures: phlebotomy, intravenous (IV) catheter insertion, arterial blood gas (ABG), nasogastric (NG) tube insertion, lumbar puncture (LP), and Foley catheter insertion. RESULTS: Four hundred sixty-seven of 601 possible surveys (across both years and both rotations) were completed (78% response rate). During both rotations, relatively few students performed the procedures, ranging from 9% for Foley catheter insertion (24/208) to 50% for both ABG and NG tube insertion (130/259). The two procedures most often performed were ABG (range 46â50%) and NG tube insertion (range 42â50%). Feelings of competency varied from 12% (LP) to 82% (Foley catheter). Except for LP, if students performed a procedure at least once, they reported feeling more competent (range 85% for ABG to 96% for Foley catheter insertion). Among the students who performed LP during a rotation, many still did not feel competent performing LPs: 23 (74%) in rotation 1 and 20 (40%) in rotation 2. CONCLUSION: Many fourth-year students at UCCOM do not perform basic procedures during their acting internship rotations. Procedural performance correlates with feelings of competency. Lumbar puncture competency may be too ambitious a goal for medical students
Measurement of laser intensities approaching 10 15 W/cm 2 with an accuracy of 1%
Accurate knowledge of the intensity of focused ultrashort laser pulses is crucial to the correct interpretation of experimental results in strong-field physics. We have developed a technique to measure laser intensities approaching 1015W/cm2 with an accu
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