Preliminary testing of a prototype portable X-ray fluorescence spectrometer

A portable X-ray fluorescence spectrometer for use as an analyzer in mineral resource investigative work was built and tested. The prototype battery powered spectrometer, measuring 11 by 12 by 5 inches and weighing only about 15 pounds, was designed specifically for field use. The spectrometer has two gas proportional counters and two radioactive sources, Cd (10a) and Fe (55). Preliminary field and laboratory tests on rock specimens and rock pulps have demonstrated the capability of the spectrometer to detect 33 elements to date. Characteristics of the system present some limitations, however, and further improvements are recommended

Sentencing Disparities in Yakima County: The Washington Sentencing Reform Act Revisited

This study expands upon an earlier exploration of sentencing disparity in the Yakima County, Washington judicial system. The Sentencing Reform Act was adopted in 1981, becoming effective in 1984, to end inequitable sentences imposed on individuals who are convicted of similar offenses. This work adds to the original study by including an investigation of exceptional sentences and offense type crime. Independent variables are defendants\u27 ethnicity (Hispanic, Native American, and White), age, and gender. The period of investigation includes fiscal years 1986 through 1991. Data was provided to the researchers by the Washington Sentencing Guidelines Commission and was processed using a difference of means test (ANOVA program). The findings suggest that sentencing disparity, while not being widespread, does persist nearly a decade after the Sentencing Reform Act was adopted. Hispanic defendants who had no prior criminal history were apt to receive disproportionately more severe sentences for similar crimes than Native Americans or whites

The VLT-FLAMES survey of massive stars: Mass loss and rotation of early-type stars in the SMC

We have studied the optical spectra of a sample of 31 O- and early B-type stars in the Small Magellanic Cloud, 21 of which are associated with the young massive cluster NGC 346. Stellar parameters are determined using an automated fitting method. Comparison with predictions of stellar evolution that account for stellar rotation does not result in a unique age, though most stars are best represented by an age of 1-3 Myr. The present day v_sini distribution of the 21 dwarf stars in our sample is consistent with an underlying rotational velocity (v_r) distribution that can be characterised by a mean velocity of about 160-190 km/s and an effective half width of 100-150 km/s. The v_r distribution must include a small percentage of slowly rotating stars. If predictions of the time evolution of the equatorial velocity for massive stars within the environment of the SMC are correct, the young age of the cluster implies that this underlying distribution is representative for the initial rotational velocity distribution. The location in the Hertzsprung-Russell diagram of the stars showing helium enrichment is in qualitative agreement with evolutionary tracks accounting for rotation, but not for those ignoring v_r. The mass loss rates of the SMC objects having luminosities of log L/L_sun > 5.4 are in excellent agreement with predictions. However, for lower luminosity stars the winds are too weak to determine M_dot accurately from the optical spectrum. Two of three spectroscopically classified Vz stars from our sample are located close to the theoretical zero age main sequence, as expected.Comment: 35 pages, accepted for publication in A&

The effects of impurities on the performance of silicon solar cells

The major factors that determine the tolerable concentrations of impurities in silicon feedstock for solar cells used in power generation are discussed in this report. It is concluded that a solar-grade silicon can be defined only for a specific manufacturing process. It is also concluded that it is the electrical effects, efficiency and resistivity, that are dominant in determining tolerable concentrations of impurities in the silicon feedstock. Crystal growth effects may become important when faster growth rates and larger crystal diameters are developed and used

Electron Conditioning of Technical Aluminium Surfaces: Effect on the Secondary Electron Yield

The effect of electron conditioning on commercially aluminium alloys 1100 and 6063 were investigated. Contrary to the assumption that electron conditioning, if performed long enough, can reduce and stabilize the SEY to low values ($\leq 1.3$, value of many pure elements), the SEY of aluminium did not go lower than 1.8. In fact, it reincreases with continued electron exposure dose.Comment: 36 pages, 25 figures, submitted to JVST

Employment in Construction and Distribution Industries: The Impact of the New Jobs Tax Credit

Excerpt] The New Jobs Tax Credit (NJTC) offers a tax credit of fifty percent of the first $4200 of wages per employee for increases in employment of more than two percent over the previous year. Economic theory predicts that such a tax credit should stimulate employment, decrease hours worked per week, and reduce product prices of the subsidized industries. A time series analysis of the construction, retailing, and wholesaling industries finds strong support for these hypotheses. Our results suggest that the NJTC was responsible for 150,000-670,000 of the more than 1-million increase in employment that occurred between mid-1977 and mid-1978 in the construction and retailing industries. Similar analysis indicates that by June 1978, NJTC had produced roughly a 1 percentage point reduction in the margin between retail and wholesale prices of commodities that saved consumers$1.9-$3.6 billion over the course of the previous year

Repulsive force support system feasibility study

A new concept in magnetic levitation and control is introduced for levitation above a plane. A set of five vertical solenoid magnets mounted flush below the plane supports and controls the model in five degrees of freedom. The compact system of levitation coils is contained in a space 2.4 m (96 in) diameter by 1 m (40 in) deep with the top of the levitation system 0.9 m (36 in) below the center line of the suspended model. The levitated model has a permanent magnet core held in position by the five parallel superconductive solenoids symmetrically located in a circle. The control and positioning system continuously corrects for model position in five dimensions using computer current pulses superimposed on the levitation coil base currents. The conceptual designs include: superconductive and Nd-Fe-B permanent magnet model cores and levitation solenoids of either superconductive, cryoresistive, or room temperature windings

Geochronology, geochemistry and isotope tracing of the Oligocene magmatism of the Buchim–Damjan–Borov Dol ore district: Implications for timing, duration and source of the magmatism

Timing, source and magmatic evolution of the intrusions in the Buchim–Damjan–Borov Dol ore district of the Former Yugoslav Republic of Macedonia (F.Y.R.O.M.) have been studied. They intrude the Circum Rhodope Unit close to the contact with the Vardar Zone and are a part of the Late Eocene–Oligocene Macedonian Rhodope– North Aegean belt. The magmatism at Buchim–Damjan–Borov Dol occurred between 24.04 ± 0.77 and 24.51 ± 0.89 Ma, as indicated by chemical-annealing (CA)–LA ICP-MS zircon dating. Major element, trace and rare earth element analyses have been performed on the various intrusive rocks. All ore bearing magmas were classified as trachyandesitic, except the youngest intrusion which is not associated with mineralization; the Black Hill locality (24.04 ± 0.77 Ma) shows a trachytic composition. The distribution of the trace elements, enrichment of large ion lithophile elements (LILE) and depletion in high field strength elements (HFSE), indicates subduction-related magmatism; most of the magmas follow a calc-alkaline fractionation trend with shoshonitic affinities; additionally, Sr/Y (10 to 90) and La/Yb values show somesimilarities to adakite-likemagmas. Sr and Nd isotope ratios (Sri = 0.70658 to 0.70740 and Ndi = 0.512425–0.512497) showthat themagmatic productswere slightly contaminated by continental crust material, e.g., the Variscan/Cadomian basement. In the Late Eocene– Oligocene belt the magmatism between 29 and 35 Ma is dominated by crustal melting with an increase in the mantle contribution between 20 and 27 Ma. We suggest the following scenario for the magmatic history of the Buchim–Damjan–Borov Dol ore district: a slab rollback of an oceanic slab located further to the SW which led to extensional and compressional features in upper levels of the continental crust. In the middle to upper crust three consecutive crystallization stages occurred at variable depths as indicated by amphibole zonation. Mixing of newly formed crust with mantle-like affinities and continental crust material in variable degrees during the ascent of the magma can explain all geochemical characteristics. The magma crystallized as dykes or stocks near the Earth's surface (>1 km) after its final emplacement and contemporaneous hydrothermal activity led to different mineralization styles depending on the lithology of the host rocks