Beam-beam observations in the RHIC

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been in operation since 2000. Over the past decade, the luminosity in the polarized proton (p-p) operations has increased by more than one order of magnitude. The maximum total beam-beam tune shift with two collisions has reached 0.018. The beam-beam interaction leads to large tune spread, emittance growth, and short beam and luminosity lifetimes. In this article, we review the beam-beam observations during the previous RHIC p-p runs. The mechanism for particle loss is presented. The intra-beam scattering (IBS) contributions to emittance and bunch length growths are calculated and compared with the measurements. Finally, we will discuss current limits in the RHIC p-p operations and their solutions.Comment: 7 pages, contribution to the ICFA Mini-Workshop on Beam-Beam Effects in Hadron Colliders, CERN, Geneva, Switzerland, 18-22 Mar 201

A biologically active peptide in the skin of lampreys (Eudontomyzon danfordi vladykovi). [Translation from: Z.Naturforsch. (B), 26(10), 1021-1023, 1971. ]

In recent years interest in the production and description of kinin-type substances has been greatly intensified. So, for example, bradykinin, phyllokinin, physalaemin, ranatensin and caerulein could be extracted from the skin of amphibians as well as. eledoisin out of the salivary glands of Eledon moschata. An examination of lampreys seemed to us particularly profitable in the search for the incidence of further kinins. Ammocoetes of different sizes and also adults of both sexes of the species Eudontomyzon danfordi vladykovi were studied in this research. This species is found in many tributaries of the Danube. Skin extracts were tested on on isolated rat uterus, rat duodenum, guinea pig ileum and rabbit jejunum, further tests were done in order to determine a peptide character of the biologically active substance

Statistics of some atmospheric turbulence records relevant to aircraft response calculations

Methods for characterizing atmospheric turbulence are described. The methods illustrated include maximum likelihood estimation of the integral scale and intensity of records obeying the von Karman transverse power spectral form, constrained least-squares estimation of the parameters of a parametric representation of autocorrelation functions, estimation of the power spectra density of the instantaneous variance of a record with temporally fluctuating variance, and estimation of the probability density functions of various turbulence components. Descriptions of the computer programs used in the computations are given, and a full listing of these programs is included

Mechanistic Links Between the Sedimentary Redox Cycle and Marine Acid-Base Chemistry

The redox state of Earth's surface is controlled on geological timescales by the flow of electrons through the sedimentary rock cycle, mediated largely by the weathering and burial of C‐S‐Fe phases. These processes buffer atmospheric pO₂. At the same time, CO₂ influxes and carbonate burial control seawater acid‐base chemistry and climate over long timescales via the carbonate‐silicate cycle. However, these two systems are mechanistically linked and impact each other via charge balance in the hydrosphere. Here, we use a low‐order Earth system model to interrogate a subset of these connections, with a focus on changes that occur during perturbations to electron flow through the sedimentary rock cycle. We show that the net oxidation or reduction of the Earth's surface can play an important role in controlling acid‐base processes in the oceans and thus climate, and suggest that these links should be more fully integrated into interpretive frameworks aimed at understanding Earth system evolution throughout Precambrian and Phanerozoic time

Lipschitz-continuity of the integrated density of states for Gaussian random potentials

The integrated density of states of a Schroedinger operator with random potential given by a homogeneous Gaussian field whose covariance function is continuous, compactly supported and has positive mean, is locally uniformly Lipschitz-continuous. This is proven using a Wegner estimate

Geochemical support for a climbing habit within the Paleozoic seed fern genus Medullosa

A long-standing problem in paleobotany is the accurate identification of the growth habits and statures of fossil plants. Tissue-specific analysis of stable carbon isotope ratios in plant fossils can provide an independent perspective on this issue. Lignin, a fundamental biopolymer providing structural support in plant tissues and the second most abundant organic material in plants, is ^(13)C depleted by several parts per thousand, averaging 4.1‰, relative to other plant constructional materials (e.g. cellulose). With this isotopic difference, the biochemical structural composition of ancient plants (and inferred stature) can be interrogated using microscale in situ isotope analysis between different tissues in fossils. We applied this technique to a well-preserved specimen of the Late Paleozoic seed plant Medullosa, an extinct genus with a variety of growth habits that includes several enigmatic yet abundant small-stemmed species widely found in calcium carbonate concretions (“coal balls”) in the Pennsylvanian coal beds of Iowa, USA. It remains unclear which of the medullosans were freestanding, and recent analysis of the medullosan vascular system has shown that this system provided little structural support to the whole plant. The leading hypothesis for small-stemmed medullosan specimens predicts that cortical tissues could have provided additional structural support, but only if they were lignified. The expected isotopic difference between lignified tissue and unlignified tissue is smaller than that expected from pure extracts, for the simple reason that even woody tissues maximally contain 40% lignin (by mass). This reduces the expected maximum difference between weakly and heavily lignified tissues by 60%, down to ~0.5‰–2‰. Analysis of the medullosan stem reveals a consistent difference in isotope ratios of 0.7‰–1.0‰ between lignified xylem and cortical tissues. This implies low abundances of lignin (between 0% and 11%) within the cortex. This inferred structural biochemistry supports hypotheses that the peripheral portions of these medullosan stems were not biomechanically reinforced to permit the plants to grow as freestanding, arborescent trees. A number of climbing or scandent medullosans have been identified in the fossil record, and this mode of growth has been suggested to be common within the group on the basis of observations from comparative biomechanics, hydraulics, and development. Finally, this mode of growth is common in several clades of stem group seed plants, including Lyginopteris and Callistophyton, along with Medullosa. This study provides further support for ideas that place a great portion of early seed plant diversity under the canopy, rather than forming it

An Understanding of the Shoulder of Giants: Jovian Planets around Late K Dwarf Stars and the Trend with Stellar Mass

Analyses of exoplanet statistics suggest a trend of giant planet occurrence with host star mass, a clue to how planets like Jupiter form. One missing piece of the puzzle is the occurrence around late K dwarf stars (masses of 0.5-0.75Msun and effective temperatures of 3900-4800K). We analyzed four years of Doppler radial velocities data of 110 late K dwarfs, one of which hosts two previously reported giant planets. We estimate that 4.0+/-2.3% of these stars have Saturn-mass or larger planets with orbital periods <245d, depending on the planet mass distribution and RV variability of stars without giant planets. We also estimate that 0.7+/-0.5% of similar stars observed by Kepler have giant planets. This Kepler rate is significantly (99% confidence) lower than that derived from our Doppler survey, but the difference vanishes if only the single Doppler system (HIP 57274) with completely resolved orbits is considered. The difference could also be explained by the exclusion of close binaries (without giant planets) from the Doppler but not Kepler surveys, the effect of long-period companions and stellar noise on the Doppler data, or an intrinsic difference between the two populations. Our estimates for late K dwarfs bridge those for solar-type stars and M dwarfs and support a positive trend with stellar mass. Small sample size precludes statements about finer structure, e.g. a "shoulder" in the distribution of giant planets with stellar mass. Future surveys such as the Next Generation Transit Survey and the Transiting Exoplanet Satellite Survey will ameliorate this deficiency.Comment: Accepted to The Astrophysical Journa

The thermal power of aluminum nitride at temperatures between 1350 and 1650 deg C in argon and nitrogen atmospheres

The test apparatus for measuring the thermal voltage of aluminum nitride for temperature differences of up to + or - 60 C between 1350 and 1650 C is described. The thermal power and its homogeneous proportion are determined and the heat transfer of the migration ions resulting from the homogeneous thermal power is calculated. The conduction mechanism in aluminum nitride is discussed