57 research outputs found

    Energy Loss, Electron Screening, and the Astrophysical 3He(d,p)4He cross section

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    We reanalyze the low-energy 3He(d,p)4He cross section measurements of Engstler et al. using recently measured energy loss data for proton and deuteron beams in a helium gas. Although the new 3He(d,p)4He S-factors are significantly lower than those reported by Engstler et al. they clearly show the presence of electron screening effects. From the new S-factors we find an electron screening energy in agreement with the adiabatic limit.Comment: 8 Page RevTeX document, two postscript figures, now in a self-extracting uufile type archiv

    Critical Review of Theoretical Models for Anomalous Effects (Cold Fusion) in Deuterated Metals

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    We briefly summarize the reported anomalous effects in deuterated metals at ambient temperature, commonly known as "Cold Fusion" (CF), with an emphasis on important experiments as well as the theoretical basis for the opposition to interpreting them as cold fusion. Then we critically examine more than 25 theoretical models for CF, including unusual nuclear and exotic chemical hypotheses. We conclude that they do not explain the data.Comment: 51 pages, 4 Figure

    The Effect of Bound Dineutrons upon BBN

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    We have examined the effects of a bound dineutron, n2, upon big bang nucleosynthesis (BBN) as a function of its binding energy B_n2. We find a weakly bound dineutron has little impact but as B_n2 increases its presence begins to alter the flow of free nucleons to helium-4. Due to this disruption, and in the absence of changes to other binding energies or fundamental constants, BBN sets a reliable upper limit of B_n2 <~ 2.5 MeV in order to maintain the agreement with the observations of the primordial helium-4 mass fraction and D/H abundance

    The role of changing geodynamics in the progressive contamination of Late Cretaceous to Late Miocene arc magmas in the southern Central Andes

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    The tectonic and geodynamic setting of the southern Central Andean convergent margin changed significantly between the Late Cretaceous and the Late Miocene, influencing magmatic activity and its geochemical composition. Here we investigate how these changes, which include changing slab-dip angle and convergence angles and rates, have influenced the contamination of the arc magmas with crustal material. Whole rock geochemical data for a suite of Late Cretaceous to Late Miocene arc rocks from the Pampean flat-slab segment (29–31 °S) of the southern Central Andes is presented alongside petrographic observations and high resolution age dating. In-situ U–Pb dating of magmatic zircon, combined with Ar–Ar dating of plagioclase, has led to an improved regional stratigraphy and provides an accurate temporal constraint for the geochemical data. A generally higher content of incompatible trace elements (e.g. Nb/Zr ratios from 0.019 to 0.083 and Nb/Yb from 1.5 to 16.4) is observed between the Late Cretaceous (~ 72 Ma), when the southern Central Andean margin is suggested to have been in extension, and the Miocene when the thickness of the continental crust increased and the angle of the subducting Nazca plate shallowed. Trace and rare earth element compositions obtained for the Late Cretaceous to Late Eocene arc magmatic rocks from the Principal Cordillera of Chile, combined with a lack of zircon inheritance, suggest limited assimilation of the overlying continental crust by arc magmas derived from the mantle wedge. A general increase in incompatible, fluid-mobile/immobile (e.g., Ba/Nb) and fluid-immobile/immobile (e.g., Nb/Zr) trace element ratios is attributed to the influence of the subducting slab on the melt source region and/or the influx of asthenospheric mantle. The Late Oligocene (~ 26 Ma) to Early Miocene (~ 17 Ma), and Late Miocene (~ 6 Ma) arc magmatic rocks present in the Frontal Cordillera show evidence for the bulk assimilation of the Permian–Triassic (P–T) basement, both on the basis of their trace and rare earth element compositions and the presence of P–T inherited zircon cores. Crustal reworking is also identified in the Argentinean Precordillera; Late Miocene (12–9 Ma) arc magmatic rocks display distinct trace element signatures (specifically low Th, U and REE concentrations) and contain inherited zircon cores with Proterozoic and P–T ages, suggesting the assimilation of both the P–T basement and a Grenville-aged basement. We conclude that changing geodynamics play an important role in determining the geochemical evolution of magmatic rocks at convergent margins and should be given due consideration when evaluating the petrogenesis of arc magmas.</p

    Puerto Rican Children Referred to the Catholic Charities Guidance Institute, New York City, From the Youth Board, New York City, for Placement

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    Background, Timeliness and Importance of the Study. Within the past ten years there has been a more pronounced interest in the Puerto Ricans and in Puerto Rico. Although the Puerto Ricans were granted American citizenship in 1917, they did not migrate in significant numbers to the United States until the 1920\u27s. They arrived in relatively large numbers at this time since they economically supplanted the European immigrants who were kept out by the new immigration laws. At least one half of them settled in New York City.It was not until 1946, however, that the peak of the Puerto Rican entry in the United States was reached. In 1946 there were more than five times as many migrants as in any year in the twenties

    Military-Standard Sensor Nodes for the SmartBrick Structural Health Monitoring Platform

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    The SmartBrick platform is an autonomous, wireless, and robust solution for structural health monitoring of civil infrastructures. The base station is currently in its third generation and has been laboratory and field tested in the United States and Italy. The platform has been presented in our previous publications; the focus of this paper is on recent developments made with the objective of complying with military standards for hardware, software, and communication. Specifically, we discuss the design and implementation of the second generation military-standard wireless sensor node for the SmartBrick platform, to facilitate its use in military applications, where interoperability, robustness, and reliability are of paramount concern. Two major enhancements to the sensor nodes are described in this paper. The first improvement is migrating from the DSPIC30F series to the latest DSCPIC33F series of microcontrollers. The second major improvement to the sensor node is replacing the Texas Instrument CC2480 Zigbee transceiver module with the MRF24J40MA from Microchip. These improvements have resulted in significantly lower power consumption and a longer communication range. We articulate the details of hardware and software development of the sensor node that incorporates this chip. We also describe laboratory and field tests, including underwater tests, carried out for validation of reliable operation and performance of the system
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