Frequency-dependent and correlational selection pressures have conflicting consequences for assortative mating in a color-polymorphic lizard, Uta stansburiana

Acknowledgments We would like to thank the numerous undergraduate researchers involved with this project for their invaluable assistance in lizard rearing and data collection. We also thank D. Haisten, A. Runemark, Y. Takahashi, and M. Verzijden for insightful comments on the manuscript. This project was funded by National Science Foundation DEBOS-15973 to A.G.M. and B.R.S.Peer reviewedPublisher PD

Observations of industrial sulfur flows and implications for Io

The possibility of sulfur flows on the Jovian satellite Io is discussed. Although the primary problem is lack of sufficient information to resolve the issue, interpretations of existing data are hampered by poor knowledge of the thermal properties and rheologic behavior of sulfur flows, especially under conditions present on Io. Relatively few natural sulfur flows occur on Earth and only one has been seen in active flow. However, recent observations of industrial sulfur flows, which are much larger than those produced experimentally, may provide important information concerning natural sulfur flows on both Earth and Io

Quantal interferometry with dissipative internal motion

In presence of dissipation, quantal states may acquire complex-valued phase effects. We suggest a notion of dissipative interferometry that accommodates this complex-valued structure and that may serve as a tool for analyzing the effect of certain kinds of external influences on quantal interference. The concept of mixed-state phase and concomitant gauge invariance is extended to dissipative internal motion. The resulting complex-valued mixed-state interference effects lead to well-known results in the unitary limit and in the case of dissipative motion of pure quantal states. Dissipative interferometry is applied to fault-tolerant geometric quantum computation.Comment: Slight revision, journal reference adde

Shaped nozzles for cryogenic buffer gas beam sources

Cryogenic buffer gas beams are important sources of cold molecules. In this work we explore the use of a converging-diverging nozzle with a buffer-gas beam. We find that, under appropriate circumstances, the use of a nozzle can produce a beam with improved collimation, lower transverse temperatures, and higher fluxes per solid angle

Non-linear Microwave Surface Impedance of Epitaxial HTS Thin Films in Low DC Magnetic Fields

We have carried out non-linear microwave (8 GHz) surface impedance measurements of three YBaCuO thin films in dc magnetic fields $H_{dc}$ (parallel to c axis) up to 12 mT using a coplanar resonator technique. In zero dc field the three films, deposited by the same method, show a spread of low-power residual surface resistance, $R_{res}$ and penetration depth, $\lambda$ (T=15 K) within a factor of 1.9. However, they exhibit dramatically different microwave field, $H_{rf}$ dependences of the surface resistance, $R_s$, but universal $X_s(H_{rf})$ dependence. Application of a dc field was found to affect not only absolute values of $R_s$ and $X_s$, but the functional dependences $R_s(H_{rf})$ and $X_s(H_{rf})$ as well. For some of the samples the dc field was found to decrease $R_s$ below its zero-field low-power value.Comment: 4 pages, 4 figures. To be published in IEEE Trans. Appl. Supercond., June 199

Initial geomagnetic field model from MAGSAT

Magsat data from magnetically quiet days were used to derive a thirteenth degree and order spherical harmonic geomagnetic field model, MGST(3/80). The model utilized both scalar and vector data and fit that data with standard deviations of 8, 52, 55 and 97 nT for the scalar magnitude, B sub r, B sub theta and B sub phi respectively. When compared with earlier models, the Earth's dipole moment continues to decrease at a rate of about 26 nT/year. Evaluation of earlier models with Magsat data shows that the scalar field at the Magsat epoch is best predicted by the POGO(2/72) model but that the AWC/75 and IGS/75 are better for predicting vector fields

Search for long lived charged massive particles in pp collisions at s-hat = 1.8TeV

We report a search for the production of long-lived charged massive particles in a data sample of 90   pb-1 of √s=1.8   TeV pp̅ collisions recorded by the Collider Detector at Fermilab. The search uses the muonlike penetration and anomalously high ionization energy loss signature expected for such a particle to discriminate it from backgrounds. The data are found to agree with background expectations, and cross section limits of O(1) pb are derived using two reference models, a stable quark and a stable scalar lepton

Slow synaptic transmission in frog sympathetic ganglia

Bullfrog ganglia contain two classes of neurone, B and C cells, which receive different inputs and exhibit different slow synaptic potentials. B cells, to which most effort has been directed, possess slow and late slow EPSPs. The sEPSP reflects a muscarinic action of acetylcholine released from boutons on B cells, whereas the late sEPSP is caused by a peptide (similar to teleost LHRH) released from boutons on C cells. During either sEPSP there is a selective reduction in two slow potassium conductances, designated 'M' and 'AHP'. The M conductance is voltage dependent and the AHP conductance is calcium dependent. Normally they act synergistically to prevent repetitive firing of action potentials during maintained stimuli. Computer stimulation of the interactions of these conductances with the other five voltage-dependent conductances present in the membrane allows a complete reconstruction of the effects of slow synaptic transmission on electrical behaviour

Zinc calixarene complexes for the ring opening polymerization of cyclic esters

Reaction of Zn(C₆F₅)₂·toluene (two equivalents) with 1,3-dipropoxy-p-tert-butyl-calix[4]arene (L¹H₂) led to the isolation of the complex [{Zn(C₆F₅)}₂L¹] (1), whilst similar use of Zn(Me)₂ resulted in the known complex [{Zn(Me)}₂L¹] (2). Treatment of L¹H₂ with in situ prepared Zn{N(SiMe₃)₂}₂ in refluxing toluene led to the isolation of the compound [(Na)ZnN(SiMe₃)₂L¹] (3). The stepwise reaction of L¹H₂ and sodium hydride, followed by ZnCl₂ and finally NaN(SiMe₃)₂ yielded the compound [Zn{N(SiMe₃)₂}₂L¹] (4). The reaction between three equivalents of Zn(C₆F₅)₂·toluene and oxacalix[3]arene (L²H₃) at room temperature formed the compound {[Zn(C₆F₅)]₃L²} (5); heating of 5 in acetonitrile caused the ring opening of the parent oxacalix[3]arene and rearrangement to afford the complex [(L²)Zn₆(C₆F₅)(R)(RH)OH]·5MeCN R = C₆F₅CH₂-(p-ᵗBuPhenolate-CH₂OCH₂–)₂–p-ᵗBuPhenolate-CH₂O⁻)³⁻ (6). The molecular structures of the new complexes 1, 3 and 6, together with that of the known complex 2, whose solid state structure has not previously been reported, have been determined. Compounds 1, 3–5 have been screened for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) and rac-lactide. Compounds featuring a Zn–C₆F₅ fragment were found to be poor ROP pre-catalysts as they did not react with benzyl alcohol to form an alkoxide. By contrast, compound 4, which contains a zinc silylamide linkage, was the most active of the zinc-based calix[4]arene compounds screened and was capable of ROP at ambient temperature with 65% conversion over 4 h

Probabilities in the inflationary multiverse

Inflationary cosmology leads to the picture of a "multiverse," involving an infinite number of (spatially infinite) post-inflationary thermalized regions, called pocket universes. In the context of theories with many vacua, such as the landscape of string theory, the effective constants of Nature are randomized by quantum processes during inflation. We discuss an analytic estimate for the volume distribution of the constants within each pocket universe. This is based on the conjecture that the field distribution is approximately ergodic in the diffusion regime, when the dynamics of the fields is dominated by quantum fluctuations (rather than by the classical drift). We then propose a method for determining the relative abundances of different types of pocket universes. Both ingredients are combined into an expression for the distribution of the constants in pocket universes of all types.Comment: 18 pages, RevTeX 4, 2 figures. Discussion of the full probability in Sec.VI is sharpened; the conclusions are strengthened. Note added explaining the relation to recent work by Easther, Lim and Martin. Some references adde