Recent instrumentation for the optical studies of solids in the vacuum ultra-violet

Optical studies of solids in vacuum ultraviolet - solid state physic

The FERRUM project: Experimental lifetimes and transition probabilities from highly excited even 4d levels in Fe ii

We report lifetime measurements of the 6 levels in the 3d6(5D)4d e6G term in Fe ii at an energy of 10.4 eV, and f -values for 14 transitions from the investigated levels. The lifetimes were measured using time-resolved laser-induced fluorescence on ions in a laser-produced plasma. The high excitation energy, and the fact that the levels have the same parity as the the low-lying states directly populated in the plasma, necessitated the use of a two-photon excitation scheme. The probability for this process is greatly enhanced by the presence of the 3d6(5D)4p z6F levels at roughly half the energy difference. The f -values are obtained by combining the experimental lifetimes with branching fractions derived using relative intensities from a hollow cathode discharge lamp recorded with a Fourier transform spectrometer. The data is important for benchmarking atomic calculations of astrophysically important quantities and useful for spectroscopy of hot stars.Comment: A&A, accepte

Demographics and the Political Sustainability of Pay-as-you-go Social Security

The net present value of costs and benefits from a pay-as-you-go social security system are negative for young people and positive for the elderly. If people all vote their financial self-interest, there will be a pivotal age such that those who are younger favor smaller social security benefits and those who are older will favor larger benefits. For persons of each age and sex, we estimate the expected present value gained or lost from a small permanent increase in the amount of benefits, where the cost of these benefits is divided equally among the population of working age. Assuming that everyone votes his or her long run financial self-interest, and calculating the number of voters in the population of each age and sex, we can determine whether there is majority support for an increase or a decrease in social security benefits. We use statistics on the age distribution and mortality rates for the United States to explore the sensitivity of political support for social security to alternative assumptions about the discount rate, excess burden in taxation, voter participation rates, and birth, death, and migration rates. We find that a once-and-for-all decrease in benefits would be defeated by a majority of selfish voters under a wide range of parameters. We also study the predicted majority outcomes of votes on changing the retirement age.

Electromagnetic energy transfer and switching in nanoparticle chain arrays below the diffraction limit

Electromagnetic energy transfer in plasmon wires consisting of chains of closely spaced metal nanoparticles can occur below the diffraction limit by means of coupled plasmon modes. Coherent propagation with group velocities that exceed 0.1 c is possible in straight wires and around sharp corners (bending radius much less than wavelength of visible light). Energy transmission through chain networks is possible at high efficiencies and is a strong function of the frequency and polarization direction of the plasmon mode. Although these structures exhibit transmission losses due to heating of about 3 dB/500 nm, they have optical functionality that cannot be obtained in other ways at a length scale ≪1 μm

The Acute Effect of a Mandibular Repositioning Appliance on Force Production During an Isometric Clean Pull in Recreationally Trained Males

ABSTRACT DANIEL HARTMAN: The Acute Effect of a Mandibular Repositioning Appliance on Force Production During an Isometric Clean Pull in Recreationally Trained Males (Under the direction of Dr. John Garner) The use of a performance mouthpiece may cause notable performance changes in an isometric mid-thigh clean pull (iMTCP) due to altered muscular force production. The purpose of this study was to examine the effects of wearing various mouthpieces coupled with a clenching of the jaw on iMTCP force production. Three recreationally trained college-aged males (Age: 26.67 ± 2.89) volunteered to participate in three testing sessions separated by one week each. In the three sessions, the subject performed repetitions of an iMTCP under the following conditions: performance mouthpiece with jaw clenched (PMP-JC), performance mouthpiece with no clench (PMP-NC), traditional mouthpiece with jaw clenched (TMP-JC), traditional mouthpiece with no clench (TMP-NC), no mouthpiece with jaw clenched (NoMP-JC), and no mouthpiece with no clench (NoMP-NC). The iMTCP assessment was measured using a Jones Machine® with a modified fixed bar allowing the subject’s strength to be transferred onto a force plate via ground reaction force. The force plate analyzed the subject’s clean pull trials as the collected data was used to calculate the subject’s peak force (Fz), normalized peak force (nFz), and rate of force development (RFD). There were no significant differences (p > .05) or interactions found in Fz between the test trials. Similarly, for nFz and RFD, no significant differences (p >.05) or interactions were found between conditions. Therefore, the subjects’ iMTCP assessments showed no overall interactions or improvements between conditions for this study. This goes to show that there is no overall benefit to wearing any sort of performance mouthpiece in hopes of generating a larger force production

A vision for leading effective schools : a reflective essay

We will face many challenges in the year 2000 and beyond - societal issues, economic issues, educational issues. The school in which I work will strive to promote leadership in all teachers, form a community of lifelong learners, and evaluate and grow professionally together. It is not my goal to manage with a top-down approach. It is my vision that I will lead the school community into exceptional instruction and learning. Leadership strengths will flow from a shared vision, values, and personal reflection. I do believe that by following these three tenets, I will lead the kids of today into a promising and successful tomorrow