Emittance compensation with dynamically optimized photoelectron beam profiles

Much of the theory and experimentation concerning creation of a high-brightness electron beam from a photocathode, and then applying emittance compensation techniques, assumes that one must strive for a uniform density electron beam, having a cylindrical shape. On the other hand, this shape has large nonlinearities in the space-charge field profiles near the beam's longitudinal extrema. These nonlinearities are known to produce both transverse and longitudinal emittance growth. On the other hand, it has recently been shown by Luiten that by illuminating the cathode with an ultra-short laser pulse of appropriate transverse profile, a uniform density, ellipsoidally shaped bunch is dynamically formed, which then has linear space-charge fields in all dimensions inside of the bunch. We study here this process, and its marriage to the standard emittance compensation scenario that is implemented in most recent photoinjectors. It is seen that the two processes are compatible, with simulations indicating a very high brightness beam can be obtained. The robustness of this scheme to systematic errors is examined. Prospects for experimental tests of this scheme are discussed

Increasing Onshore Oil Production: An Unexpected Explosion in Trauma Patients

Introduction. Few data currently exist which are focused on typeand severity of onshore oil extraction-related injuries. The purposeof this study was to evaluate injury patterns among onshore oil fieldoperations. Methods. A retrospective review was conducted of all traumapatients aged 18 and older with an onshore oil field-related injuryadmitted to an American College of Surgeons-verified level 1 traumacenter between January 1, 2003 and June 30, 2012. Data collectedincluded demographics, injury severity and details, hospital outcomes,and disposition. Results. A total of 66 patients met inclusion criteria. All patientswere male, of which the majority were Caucasian (81.8%, n = 54)with an average age of 36.5 ± 11.8 years, injury severity score of 9.4 ±8.9, and Glasgow Coma Scale score of 13.8 ± 3.4. Extremity injurieswere the most common (43.9%, n = 29), and most were the resultof being struck by an object (40.9%, n = 27). Approximately onethirdof patients (34.8%, n = 23) were admitted to the intensive careunit. Nine patients (13.6%) required mechanical ventilation while27 (40.9%) underwent operative treatment. The average hospitallength of stay was 5.8 ± 16.6 days, and most patients (78.8%, n = 52)were discharged home. Four patients suffered permanent disabilities,and there were two deaths. Conclusions. Increased domestic onshore oil production inevitablywill result in higher numbers of oil field-related traumas. By focusingon employees who are at the greatest risk for injuries and by targetingthe main causes of injuries, training programs can lead to a decreasein injury incidence. Kans J Med 2018;11(2):34-37

Critical slowing down in polynomial time algorithms

Combinatorial optimization algorithms which compute exact ground state configurations in disordered magnets are seen to exhibit critical slowing down at zero temperature phase transitions. Using arguments based on the physical picture of the model, including vanishing stiffness on scales beyond the correlation length and the ground state degeneracy, the number of operations carried out by one such algorithm, the push-relabel algorithm for the random field Ising model, can be estimated. Some scaling can also be predicted for the 2D spin glass.Comment: 4 pp., 3 fig

Issues in the determination of “responders” and “non‐responders” in physiological research

As a follow-up to our 2015 review, we cover more issues on the topic of “response heterogeneity”, which we define as clinically-important individual differences in the physiological responses to the same treatment or intervention that cannot be attributed to random within-subjects variability. We highlight various pitfalls with the common practice of counting the number of “responders”, “non-responders” and “adverse responders” in samples that have been given certain treatments/interventions for research purposes. We focus on the classical parallel-group randomised controlled trial (RCT) design and assume typical good practice in trial design.We show that sample responder counts are biased because individuals differ in terms of pre-to-post within-subjects random variability in the study outcome(s) and not necessarily treatment response. Ironically, sample differences in responder counts may be explained wholly by sample differences in mean response, even if there is no response heterogeneity at all. Sample comparisons of responder counts also have relatively low statistical precision. These problems do not depend on how the response threshold has been selected, e.g. on the basis of a measurement error statistic, and are not rectified fully by the use of confidence intervals for individual responses in the sample