3,021 research outputs found

    Coherent photodissociation reactions: Observation by a novel picosecond polarization technique

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    In this communication, we wish to report on a novel picosecond polarization method for measuring the degree of rotational coherence that is preserved in photodissociation reactions. The systems studied here are jet-cooled van der Waals molecules; stilbene [4-6] bound [5] to He or Ne with a 1:1 composition.[7

    Theory of one-dimensional double-barrier quantum pump in two-frequency signal regime

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    A one-dimensional system with two δ\delta-like barriers or wells bi-chromaticaly oscillating at frequencies ω\omega and 2ω2\omega is considered. The alternating signal leads to the direct current across the structure (even in a symmetric system). The properties of this quantum pump are studied in a wide range of the system parameters.Comment: 4 pages, 5 figure

    Enhancing Nurses\u27 Pain Reassessment and Documentation Using Clinical Decision Support: A Quality Improvement Project in Acute Care

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    Purpose: The project aimed to educate medical-surgical registered nurses (RNs) on using the clinical decision support (CDS) tools to complete pain reassessment and documentation. Objectives were to increase pain reassessment compliance, identify perceived pain reassessment barriers, and change current pain reassessment and documentation behaviors. Background: Nurses are responsible for assessing, reassessing, and managing patients’ pain. Quality pain reassessment and documentation are essential to effective pain management. Methods: Participants were accrued via convenience sampling in addition to inclusion and exclusion criteria. The Plan-Do-Check-Act (PDCA) Cycle was used to guide the pilot project conducted in one medical-surgical unit. Implementation interventions: asynchronous computer-based learning module with step-by-step instruction and demonstration on how to use the CDS tools, dissemination of tip sheets to reinforce learning module content, unit rounding, and distribution of information on the importance of pain reassessment and documentation. Participants were also invited to complete an electronic questionnaire to evaluate demographics and perceived pain reassessment barriers. Results: 18 participants completed the project. The educational intervention had a small effect on the participants’ pain reassessment compliance one-week post-intervention. By the second post-intervention week, compliance dipped and regressed to baseline. The primary barriers contributing to participants’ pain reassessment compliance rates were time constraints, competing patient care priorities, heavy workload, inadequate staffing, and forgetfulness. Conclusion: The project results suggest that an educational intervention focused on CDS tools could improve nurses’ pain reassessment and documentation compliance and behaviors

    Ultrafast vectorial and scalar dynamics of ionic clusters: Azobenzene solvated by oxygen

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    The ultrafast dynamics of clusters of trans-azobenzene anion (A–) solvated by oxygen molecules was investigated using femtosecond time-resolved photoelectron spectroscopy. The time scale for stripping off all oxygen molecules from A– was determined by monitoring in real time the transient of the A– rise, following an 800 nm excitation of A– (O2)n, where n=1–4. A careful analysis of the time-dependent photoelectron spectra strongly suggests that for n>1 a quasi-O4 core is formed and that the dissociation occurs by a bond cleavage between A– and conglomerated (O2)n rather than a stepwise evaporation of O2. With time and energy resolutions, we were able to capture the photoelectron signatures of transient species which instantaneously rise (2- for A–O2 and A·O4-·(O2)n–2 for A–(O2)n, where n=2–4. Subsequent to an ultrafast electron recombination, A– rises with two distinct time scales: a subpicosecond component reflecting a direct bond rupture of the A–-(O2)n nuclear coordinate and a slower component (1.6–36 ps, increasing with n) attributed to an indirect channel exhibiting a quasistatistical behavior. The photodetachment transients exhibit a change in the transition dipole direction as a function of time delay. Rotational dephasing occurs on a time scale of 2–3 ps, with a change in the sign of the transient anisotropy between A–O2 and the larger clusters. This behavior is a key indicator of an evolving cluster structure and is successfully modeled by calculations based on the structures and inertial motion of the parent clusters

    Properties of 1D two-barrier quantum pump with harmonically oscillating barriers

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    We study a one-dimensional quantum pump composed of two oscillating delta-functional barriers. The linear and non-linear regimes are considered. The harmonic signal applied to any or both barriers causes the stationary current. The direction and value of the current depend on the frequency, distance between barriers, value of stationary and oscillating parts of barrier potential and the phase shift between alternating voltages.Comment: 7 pages, 8 figure

    An algorithm for the estimation of bounds on the emissivity and temperatures from thermal multispectral airborne remotely sensed data

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    The effective flux incident upon the detectors of a thermal sensor, after it has been corrected for atmospheric effects, is a function of a non-linear combination of the emissivity of the target for that channel and the temperature of the target. The sensor system cannot separate the contribution from the emissivity and the temperature that constitute the flux value. A method that estimates the bounds on these temperatures and emissivities from thermal data is described. This method is then tested with remotely sensed data obtained from NASA's Thermal Infrared Multispectral Scanner (TIMS) - a 6 channel thermal sensor. Since this is an under-determined set of equations i.e. there are 7 unknowns (6 emissivities and 1 temperature) and 6 equations (corresponding to the 6 channel fluxes), there exist theoretically an infinite combination of values of emissivities and temperature that can satisfy these equations. Using some realistic bounds on the emissivities, bounds on the temperature are calculated. These bounds on the temperature are refined to estimate a tighter bound on the emissivity of the source. An error analysis is also carried out to quantitatively determine the extent of uncertainty introduced in the estimate of these parameters. This method is useful only when a realistic set of bounds can be obtained for the emissivities of the data. In the case of water the lower and upper bounds were set at 0.97 and 1.00 respectively. Five flights were flown in succession at altitudes of 2 km (low), 6 km (mid), 12 km (high), and then back again at 6 km and 2 km. The area selected with the Ross Barnett reservoir near Jackson, Mississippi. The mission was flown during the predawn hours of 1 Feb. 1992. Radiosonde data was collected for that duration to profile the characteristics of the atmosphere. Ground truth temperatures using thermometers and radiometers were also obtained over an area of the reservoir. The results of two independent runs of the radiometer data averaged 7.03 plus or minus .70 for the first run and 7.31 plus or minus .88 for the second run. The results of the algorithm yield a temperature of 7.68 for the low altitude data to 8.73 for the high altitude data
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