Position requirements for space station personnel and linkages to portable microcomputer performance assessment

The development and use of a menu of performance tests that can be self-administered on a portable microcomputer are investigated. In order to identify, develop, or otherwise select the relevant human capabilities/attributes to measure and hence include in the performance battery, it is essential that an analysis be conducted of the jobs or functions that will be performed throughout a space shuttle mission. The primary job analysis instrument, the Position Analysis Questionnaire (PAQ), is discussed in detail so the reader will have sufficient background for understanding the application of the instrument to the various work activities included within the scope of the study, and the derivation of the human requirements (abilities/attributes) from the PAQ analyses. The research methodology is described and includes the procedures used for gathering the PAQ data. The results are presented in detail with specific emphasis on identifying critical requirements that can be measured with a portable computerized assessment battery. A discussion of the results is given with implications for future research

Efficiency for the imperfect LHC collimation system

The LHC collimation system requires a high cleaning efficiency in order to prevent magnet quenches due to regular beam diffusion. The cleaning efficiency is significantly reduced due to imperfections of the collimator jaws and the machine optics. Tracking tools have been set up to predict the cleaning efficiency in presence of multiple imperfections. The deterioration of cleaning efficiency is quantified for different errors, including collimator surface non-flatness, collimator alignment errors, beta beating, orbit errors, non-linear field errors, and chromatic effects

Quench levels and transient beam losses in LHC magnets

The last evaluation of quench levels related to transient beam losses was done in 1987 [1]. The subject is reevaluated with more detailed approach of the thermodynamics of the superconducting cables in response to a transient heat load associated to beam losses

How to identify and recruit nurses to a survey 14 and 24 years after graduation in a context of scarce data: lessons learnt from the 2012 nurses at work pilot study on nurses' career paths.

BACKGROUND: Nursing workforce data are scarce in Switzerland, with no active national registry of nurses. The worldwide nursing shortage is also affecting Switzerland, so that evidence-based results of the nurses at work project on career paths and retention are needed as part of the health care system stewardship; nurses at work is a retrospective cohort study of nurses who graduated in Swiss nursing schools in the last 30 years. Results of the pilot study are presented here (process and feasibility). The objectives are (1) to determine the size and structure of the potential target population by approaching two test-cohorts of nursing graduates (1988 and 1998); (2) to test methods of identifying and reaching them 14 and 24 years after graduation; (3) to compute participation rates, and identify recruitment and participation biases. METHODS: Graduates' names were retrieved from 26 Swiss nursing schools: 488 nurses from the 1988 cohort and 597 from 1998 were invited to complete a web-based questionnaire. Initial updated addresses (n = 278, seed sample) were found using the Swiss Nursing Association member file. In addition, a snowball method was applied for recruitment, where directly-contacted respondents provided additional names of graduate mates or sent them the invitation. The study was further advertized through the main employers, study partners, and a press release. RESULTS: Participation rate was 26.5% (n = 287), higher for the older cohort of 1988 (29.7%, n = 145) than for 1998 (15.6%, n = 93). Additional nurses (n = 363) not belonging to the test cohorts also answered. All schools were represented among respondents. Only 18 respondents (6%) worked outside nursing or not at all. Among respondents, 94% would 'probably' or 'maybe' agree to participate in the main study. CONCLUSION: The pilot study demonstrated that targeted nurses could be identified and approached. There is an overwhelming interest in the project from them and from policymakers. Recommendations to increase nurses' participation rate for nurses at work include: (1) to open nurses at work recruitment to all nurses in Switzerland, while recreating cohorts post-hoc for relevant analysis; (2) to define a comprehensive communication strategy with special attention to graduate nurses who are harder to reach

Numerical Optimization of Collimator Jaw Orientations and Locations in the LHC

The collimation system of LHC will consist of flat collimator jaws distributed along the IR7 lattice with the aim of limiting the maximum combined amplitudes of secondary halo particles (born along the edges of the primary collimators). The code DJ (Distribution of Jaws) computes this amplitude using a quasi-analytic algorithm (no tracking), by which the maximum initial angles are found, corresponding to trajectories escaping all secondary jaws. We report the latest version of DJ, which contains the following enhancements: (1) the orientation of each pair of jaws is a free variable (instead of using only vertical, horizontal, or 45 degrees skew jaws); (2) the minimizing method used is "simulated annealing", which, for our case of a discontinuous function of up to 32 variables, always finds a global minimum. Different initial jaw distributions lead to different final ones, but they all give essentially the same maximum halo amplitude; this seems to depend only on the number of jaws and the lattice parameters, particularly the tune-split. We discuss lattice characteristics found favorable for collimation

Optimization of Collimator Jaw Locations for the LHC

A highly effective collimation scheme is required in the LHC to limit heating of the vacuum chamber and superconducting magnets by protons either uncaptured at injection or scattered from the collision points. The proposed system would consist of one set of primary collimators followed by three sets of secondary collimators downstream to clean up protons scattered from the primaries. Each set of collimators would consist of four pairs of jaws - horizontal, vertical, and 45 o and 135 o skew. A study is reported of the optimization of the longitudinal positions of these jaws with the aim of minimizing the maximum betatron amplitudes of protons surviving the collimation system. This is performed using an analytical representation of the action of the jaws and is confirmed by tracking. Significant improvement can be obtained by omitting inactive jaws and adding skew jaws

Initial error analysis for the LHC collimation insertion

The two cleaning insertions in the LHC, for betatron and momentum collimation, are optimized for an ideal lattice and collimator jaw setup. We have studied a collimation beam line with randomly generated jaw misalignments and quadrupole field and alignment errors, the resultant distortion of the reference orbit being corrected with the help of monitors placed near critical collimators. Different closed orbit errors and beam shapes are considered at the entrance. We report the level of errors for which no corrections are needed and the level for which corrections are not possible

Kinetic Inductance of Josephson Junction Arrays: Dynamic and Equilibrium Calculations

We show analytically that the inverse kinetic inductance $L^{-1}$ of an overdamped junction array at low frequencies is proportional to the admittance of an inhomogeneous equivalent impedance network. The $ij^{th}$ bond in this equivalent network has an inverse inductance $J_{ij}\cos(\theta_i^0-\theta_j^0-A_{ij})$, where $J_{ij}$ is the Josephson coupling energy of the $ij^{th}$ bond, $\theta_i^0$ is the ground-state phase of the grain $i$, and $A_{ij}$ is the usual magnetic phase factor. We use this theorem to calculate $L^{-1}$ for square arrays as large as $180\times 180$. The calculated $L^{-1}$ is in very good agreement with the low-temperature limit of the helicity modulus $\gamma$ calculated by conventional equilibrium Monte Carlo techniques. However, the finite temperature structure of $\gamma$, as a function of magnetic field, is \underline{sharper} than the zero-temperature $L^{-1}$, which shows surprisingly weak structure. In triangular arrays, the equilibrium calculation of $\gamma$ yields a series of peaks at frustrations $f = \frac{1}{2}(1-1/N)$, where $N$ is an integer $\geq 2$, consistent with experiment.Comment: 14 pages + 6 postscript figures, 3.0 REVTe

Beam Dynamics Issues in the CLIC Long Transfer Line

Both the main and the drive beam of the CLIC project must be transported from the central production site to the head of the main linacs over more than twenty kilometers. Over such distances chromatic error may be substantial. With long distances and large beam currents, ion-induced detuning and instabilities and multi-bunch resistive wall effects must also be considered. These effects are quantified and simulated. Based on these results, a baseline design has been established