Exploring minimal scenarios to produce transversely bright electron beams using the eigen-emittance concept

Next generation hard X-ray free electron lasers require electron beams with low transverse emittance. One proposal to achieve these low emittances is to exploit the eigen-emittance values of the beam. The eigen-emittances are invariant under linear beam transport and equivalent to the emittances in an uncorrelated beam. If a correlated beam with two small eigen-emittances can be produced, removal of the correlations via appropriate optics will lead to two small emittance values, provided non-linear effects are not too large. We study how such a beam may be produced using minimal linear correlations. We find it is theoretically possible to produce such a beam, however, it may be more difficult to realize in practice. We identify linear correlations that may lead to physically realizable emittance schemes and discuss promising future avenues.     

Evaluation of the Dynamic Yield Locus Tester (DYLT)

ABSTRACT

Shear cells based on the constant volume approach are a promising alternative to the conventional constant load techniques. The objectives of this research were to evaluate the dynamic yield locus tester (DYLT) based on the constant volume approach, and the computer controlled Jenkie tester (CCJT) based on the constant load approach. This was done by comparing the flow parameters obtained using the two techniques for BCR limestone, glass fibers, ground silica, microcrystalline cellulose, and wheat flour. Test results showed the flow parameters obtained using the DYLT and the CCJT were comparable at a level of significance of 0.05 for BCR limestone, glass fibers, ground silica, and microcrystalline cellulose. There were significant differences (p > 0.05) between the flow parameters of the DYLT and CCJT for wheat flour.     

Rapid Prototyping of Microfluidic Systems in Poly(dimethylsiloxane)

This paper describes a procedure that makes it possible to design and fabricate (including sealing) microfluidic systems in an elastomeric material [Formula: see text] poly(dimethylsiloxane) (PDMS) [Formula: see text] in less than 24 h. A network of microfluidic channels (with width >20 μm) is designed in a CAD program. This design is converted into a transparency by a high-resolution printer; this transparency is used as a mask in photolithography to create a master in positive relief photoresist. PDMS cast against the master yields a polymeric replica containing a network of channels. The surface of this replica, and that of a flat slab of PDMS, are oxidized in an oxygen plasma. These oxidized surfaces seal tightly and irreversibly when brought into conformal contact. Oxidized PDMS also seals irreversibly to other materials used in microfluidic systems, such as glass, silicon, silicon oxide, and oxidized polystyrene; a number of substrates for devices are, therefore, practical options. Oxidation of the PDMS has the additional advantage that it yields channels whose walls are negatively charged when in contact with neutral and basic aqueous solutions; these channels support electroosmotic pumping and can be filled easily with liquids with high surface energies (especially water). The performance of microfluidic systems prepared using this rapid prototyping technique has been evaluated by fabricating a miniaturized capillary electrophoresis system. Amino acids, charge ladders of positively and negatively charged proteins, and DNA fragments were separated in aqueous solutions with this system with resolution comparable to that obtained using fused silica capillaries.     

Anatomical correction of the exstrophy-epispadias complex: analysis of 34 patients

OBJECTIVE: To evaluate the surgical procedures required for anatomical reconstruction of the bladder and penis in the exstrophy-epispadias complex. PATIENTS AND METHODS: All primary exstrophy-epispadias repairs carried out by one surgeon between 1987 and 1997 were reviewed. Bladder closure consisted of full extraperitoneal mobilization, transpositional omphaloplasty, drainage with ureteric and urethral catheters and immobilization with a 'frog-leg' plaster-cast or 'mermaid' dressings. Osteotomies were always performed when bladder closure was attempted after 37 h of age. Before 1990 the osteotomies were posterior vertical iliac (one patient) and subsequently anterior oblique iliac (10 patients). Pre-peritoneal herniotomies, in the absence of a clinical hernia, were included in the primary procedure after 1992. A modified Cantwell technique was used for epispadias repair and this was undertaken at a median of 16 months after bladder closure (range 6-30). RESULTS: Thirty-four patients (27 male) were reviewed; one patient had a chromosomal abnormality, a deletion in the short arm of chromosome 4. The male infants required a median of four procedures (range 2-5) for bladder closure, epispadias reconstruction and herniotomies, while the females needed a median of two (range 2-5). Complete bladder dehiscence, requiring re-closure with osteotomies, occurred in three cases (9%, two male). There were no dehiscences in the primary osteotomy group. Fistulae after epispadias repair occurred in four patients (17%). The bladder capacity increased to > 60 mL in 10 of 15 males by 36 months after epispadias repair. Only two of seven female infants attained a capacity of > 60 mL. Of the 15 infants who did not undergo herniotomy at primary closure, 13 subsequently developed inguinal hernias (one uni- and 11 bilateral) with incarceration occurring in two. Twelve infants underwent herniotomy at primary closure and six developed subsequent hernias (two uni- and four bilateral; P = 0.05) with documented incarceration in two. CONCLUSIONS: Anatomical correction of the exstrophy-epispadias complex remains challenging, but can be achieved with complication rates of < 20% for each stage. Bladder volumes large enough to permit adequate bladder neck reconstruction can be anticipated after epispadias repair in a large proportion of male infants, but remains small in female infants with low outlet resistance. Inguinal herniotomy at the time of bladder closure significantly reduces the incidence of subsequent herniation, which nevertheless remains high.     

Positive affectivity and negative outcomes: the role of tenure and job satisfaction

In this study, the authors proposed and tested a 3-way interaction among positive affectivity (PA), job satisfaction, and tenure in predicting negative employee outcomes. Specifically, the authors predicted that the relationship between job satisfaction and negative outcomes would be stronger for high PAs and that this relationship would be more pronounced for longer tenured employees. Results support this 3-way interaction in predicting job search behavior, physical health complaints, and counterproductive employee behavior. In particular, the relationship between job satisfaction and negative outcomes was most strongly negative for high-PA individuals with longer tenure. The authors discuss the implications of these results and some directions for future research.     

Moderators of the Relationships Between Coworkers' Organizational Citizenship Behavior and Fellow Employees' Attitudes.

The authors developed and tested the prediction that the relationship hetween coworkers' organizational citizenship behaviors (OCBs) and fellow employees' attitudes depends on the supervisors' abusiveness. Results of a longitudinal study using data collected from 173 supervised employees at 2 points in time (separated by 7 months) suggested that coworkers' OCB was positively related to fellow employees' job satisfaction and affective commitment when abusive supervision was low. However, when abusive supervision was high, coworkers' OCB was negatively related to job satisfaction and was unrelated to organizational commitment. The results of a 2nd study were consistent with the idea that the attributions employees make for their coworkers' OCB explains the moderating effect of abusive supervision on the relationship between coworkers' OCB and job satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of Work motivation: History, theory, research, and practice.

Reviews the book, Work motivation: History, theory, research, and practice by Gary Latham (see record 2006-11764-000). The reviewer commends Latham for writing an empirically comprehensive and "personal" book on work motivation. Included is a history of work motivation studies throughout the last 100 years, directions for future research, and the author's reflections on what he has learned about the field on his own professional and personal journey through life. The reviewer praises the author's style highly, and recommends this book to all. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hole pockets in the doped 2D Hubbard model

The electronic momentum distribution n(k) of the two dimensional Hubbard model is studied for different values of the coupling U/t, electronic density n , and temperature, using quantum Monte Carlo techniques. A detailed analysis of the data on 8 × 8 clusters shows that features consistent with hole pockets at momenta k=(±/2,±/2,) appear as the system is doped away from half-filling. Our results are consistent with recent experimental data for the cuprates discussed by Aebi et al. (Phys. Rev. Lett.72, 2757 (1994)). In the range of couplings studied, the depth of the pockets is maximum at n approximately 0.9, and it increases with decreasing temperature. The apparent absence of hole pockets in previous numerical studies of this model is explained.