Indirect observation of phase conjugate magnons from non-degenerate four-wave mixing

A phase conjugate mirror utilising four-wave mixing in a magnetic system is experimentally realised for the first time. Indirect evidence of continuous-wave phase conjugation has been observed experimentally and is supported by simulations. The experiment utilizes a pump-probe method to excite a four-wave mixing process. Two antennae are used to pump a region of a thin-film yttrium iron garnet waveguide with magnons of frequency $f_{1}$ to create a spatio-temporally periodic potential. As the probe magnons of $f_{\mathrm{p}}$ impinge on the pumped region, a signal with frequency $f_{\mathrm{c}} = 2f_{1}-f_{\mathrm{p}}$ is observed. The amplitude of the nonlinear signal was highly dependent on the applied magnetic field $H$. Width modes of the probe magnons and standing wave modes of the pump magnons were shown to affect the amplitude of the signal at $f_{\mathrm{c}}$. Experimental data is compared with simulations and theory to suggest that $f_{\mathrm{c}}$ is a phase conjugate of $f_{\mathrm{p}}$.Comment: 6 pages, 6 figure

Hybrid bearings for turbopumps and the like

In rocket engines power is usually obtained by burning fuel and oxidizer which are mixed, pressurized, and directed to a combustion chamber by means of turbopumps. Roller bearings are generally used in these turbopumps, but because of bearing demands hydrostatic bearings were proposed. The use of such bearings is quite feasible because during flight hydrostatic lubrication can reduce roller bearing wear. A disadvantage of such proposals is that during startup, acceleration, and shutdown high pressure fluids are not available for hydrostatic bearings. The fluid lubrication film is not always present in bearings of turbopumps. During these periods a second bearing is required to carry the load. This requirement suggests the use of hybrid bearings in rocket engine turbopumps. Such duplex bearings were provided, but when their inner races are keyed to the shaft or journal two of them are required. And such duplex bearings do not wear evenly. A hybrid hydrostatic-rolling element bearing was provided wherein the rolling element bearing is locked on the stationary housing rather than on the rotating journal

Measuring the impact of object-oriented techniques in grande applications: a method-level analysis

In this work we seek to provide a foundation for the study of the level of use of object-oriented techniques in Java programs in general, and scientific applications in particular. Specifically, we focus on the use of small methods, and the frequency with which they are called, since this forms the basis for the study of method inlining, an important optimisation technique. We compare the Grande and SPEC benchmark suites, and note a significant difference in the nature and composition of these suites

Immobilization of the Erupting Molar in the Syrian Hamster

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67148/2/10.1177_00220345650440061901.pd

Why Do Some CAHs Close Their Skilled Nursing Facility Services While Others Retain Them? (Briefing Paper #32)

Variations in reimbursement policies and swing bed use suggest that the incentives influencing the decisions of CAHs regarding their Skilled Nursing Facility (SNF) units may differ from those of urban hospitals. Based on a review of the literature and conversations with members of the Flex Monitoring Team’s Expert Work Group, we expected the financial decision regarding SNF unit operation to be more complex for CAHs than for PPS hospitals largely because the decision involves the profitability of a PPS-reimbursed SNF within a cost-based facility. In the case of the CAH, the indirect and facility costs associated with operating a PPS-reimbursed SNF unit must be subtracted from the cost base of the cost-reimbursed acute care services thereby reducing reimbursement for those services. We also expected that the availability of swing beds (which can be used effectively to manage acute care length of stay issues without compromising acute care reimbursement) would be a significant factor in decisions to close SNF units. We identified other factors that might influence a CAH’s decision to retain a SNF unit including: the need for an alternative to swing beds to manage length of stay issues for CAHs with consistently high acute care census levels; community need and preference (which might be particularly important for municipal and county-owned hospitals); and limitations on SNF unit closure imposed by state Certificate of Need regulations. Among the potential factors influencing a CAH’s decision to close or retains its SNF units, only the latter factor (i.e., the influence of Certificate of Need regulations) was not supported by our study. We interviewed 20 CAHs operating in eleven states, including 11 hospitals that had closed their SNF units and 9 that continued to operate their services. This report discusses our findings in detail; there is also a policy brief which highlights the same findings

BRITE-Constellation reveals evidence for pulsations in the enigmatic binary η\eta Carinae

$\eta$ Car is a massive, eccentric binary with a rich observational history. We obtained the first high-cadence, high-precision light curves with the BRITE-Constellation nanosatellites over 6 months in 2016 and 6 months in 2017. The light curve is contaminated by several sources including the Homunculus nebula and neighboring stars, including the eclipsing binary CPD$-$59$^\circ$2628. However, we found two coherent oscillations in the light curve. These may represent pulsations that are not yet understood but we postulate that they are related to tidally excited oscillations of $\eta$ Car's primary star, and would be similar to those detected in lower-mass eccentric binaries. In particular, one frequency was previously detected by van Genderen et al. and Sterken et al. through the time period of 1974 to 1995 through timing measurements of photometric maxima. Thus, this frequency seems to have been detected for nearly four decades, indicating that it has been stable in frequency over this time span. These pulsations could help provide the first direct constraints on the fundamental parameters of the primary star if confirmed and refined with future observations.Comment: 8 pages, 4 figures, accepted to MNRA

Genetic dissection of the tissue‐specific roles of type III effectors and phytotoxins in the pathogenicity of Pseudomonas syringae pv. syringae to cherry

When compared with other phylogroups (PGs) of the Pseudomonas syringae species complex, P. syringae pv. syringae (Pss) strains within PG2 have a reduced repertoire of type III effectors (T3Es) but produce several phytotoxins. Effectors within the cherry pathogen Pss 9644 were grouped based on their frequency in strains from Prunus as the conserved effector locus (CEL) common to most P. syringae pathogens; a core of effectors common to PG2; a set of PRUNUS effectors common to cherry pathogens; and a FLEXIBLE set of T3Es. Pss 9644 also contains gene clusters for biosynthesis of toxins syringomycin, syringopeptin and syringolin A. After confirmation of virulence gene expression, mutants with a sequential series of T3E and toxin deletions were pathogenicity tested on wood, leaves and fruits of sweet cherry (Prunus avium) and leaves of ornamental cherry (Prunus incisa). The toxins had a key role in disease development in fruits but were less important in leaves and wood. An effectorless mutant retained some pathogenicity to fruit but not wood or leaves. Striking redundancy was observed amongst effector groups. The CEL effectors have important roles during the early stages of leaf infection and possibly acted synergistically with toxins in all tissues. Deletion of separate groups of T3Es had more effect in P. incisa than in P. avium. Mixed inocula were used to complement the toxin mutations in trans and indicated that strain mixtures may be important in the field. Our results highlight the niche‐specific role of toxins in P. avium tissues and the complexity of effector redundancy in the pathogen Pss 9644