Specific Heat of Disordered 3^{3}He

Porous aerogel is a source of elastic scattering in superfluid 3He and modifies the properties of the superfluid, suppressing the transition temperature and order parameter. The specific heat jumps for the B-phase of superfluid 3He in aerogel have been measured as a function of pressure and interpreted using the homogeneous and inhomogeneous isotropic scattering models. The specific heat jumps for other p-wave states are estimated for comparison.Comment: Manuscript prepared for LT 2

The response of calcifying plankton to climate change in the Pliocene

As a result of anthropogenic pCO2 increases, future oceans are growing warmer and lower in pH and oxygen, conditions that are likely to impact planktic communities. Past intervals of elevated and changing pCO2 and temperatures can offer a glimpse into the response of marine calcifying plankton to changes in surface oceans under conditions similar to those projected for the future. Here we present new records of planktic foraminiferal and coccolith calcification (weight and size) from Deep Sea Drilling Project Site 607 (mid-North Atlantic) and Ocean Drilling Program Site 999 (Caribbean Sea) from the Pliocene, the last time that pCO2 was similar to today, and extending through a global cooling event into the intensification of Northern Hemisphere glaciation (3.3 to 2.6 million years ago). Test weights of both surface-dwelling Foraminifera Globigerina bulloides and thermocline-dwelling Foraminifera Globorotalia puncticulata vary with a potential link to regional temperature variation in the North Atlantic, whereas in the tropics Globigerinoides ruber test weight remains stable. In contrast, reticulofenestrid coccoliths show a narrowing size range and a decline in the largest lith diameters over this interval. Our results suggest no major changes in plankton calcite production during the high pCO2 Pliocene or during the transition into an icehouse world.</p

Uniaxial-stress induced phase transitions in [001]c-poled 0.955Pb(Zn1/3Nb2/3)O3-0.045PbTiO3

First-order, rhombohedral to orthorhombic, stress-induced phase transitions have been evidenced by bulk charge-stress measurements and X-ray diffraction derived lattice strain measurements in [001]c-poled PZN-4.5PT. The transitions are induced by uniaxial, compressive loads applied either along or perpendicular to the poling direction. In each case, they occur via rotation of the polar vector in the Cm monoclinic plane and the induced lattice strain is hysteretic yet reversible. Although no depoling is observed in the transverse mode, net depolarization is observed under longitudinal stress which is important for the use of [001]c-poled PZN-PT and PMN-PT single crystals in Tonpilz-type underwater projectors.Comment: To be published in Applied Physics Letters, 16 pages, 3 figure

Absolute instabilities of travelling wave solutions in a Keller-Segel model

We investigate the spectral stability of travelling wave solutions in a Keller-Segel model of bacterial chemotaxis with a logarithmic chemosensitivity function and a constant, sublinear, and linear consumption rate. Linearising around the travelling wave solutions, we locate the essential and absolute spectrum of the associated linear operators and find that all travelling wave solutions have essential spectrum in the right half plane. However, we show that in the case of constant or sublinear consumption there exists a range of parameters such that the absolute spectrum is contained in the open left half plane and the essential spectrum can thus be weighted into the open left half plane. For the constant and sublinear consumption rate models we also determine critical parameter values for which the absolute spectrum crosses into the right half plane, indicating the onset of an absolute instability of the travelling wave solution. We observe that this crossing always occurs off of the real axis

Semi-Empirical Bound on the Chlorinr-37 Solar Neutrino Experiment

The Kamiokande measurement of energetic Boron-8 neutrinos from the sun is used to set a lower bound on the contribution of the same neutrinos to the signal in the \Chlorine\ experiment. Implications for Beryllium-7 neutrinos are discussed.Comment: Latex, 6 pages + 1 postscript figure (included). UTAPHY-HEP-

Water Vapour Effects in Mass Measurement

Water vapour inside the mass comparator enclosure is a critical parameter. In fact, fluctuations of this parameter during mass weighing can lead to errors in the determination of an unknown mass. To control that, a proposal method is given and tested. Preliminary results of our observation of water vapour sorption and desorption processes from walls and mass standard are reported