The effect of a concentration-dependent viscosity on\ud particle transport in a channel flow with porous walls

We analyse the transport of a dilute suspension of particles through a channel with porous walls accounting for the concentration dependence of the viscosity. Two cases of leakage flow of fluid through the porous channel walls are studied: (i) constant flux, and (ii) dependent on the pressure drop across the wall. The effect of mixing the suspension first compared with point injection is examined by considering inlet concentration distributions of different widths. We find that a pessimal distribution width exists that maximizes the required hydrodynamic pressure for a constant fluid influx. We also show that the presence of an osmotic pressure may lead to fluid being sucked into the channel. We consider how the application of an external hydrodynamic pressure affects this observation and discuss the significance of our results for water filtration

The combined use of selective deuteration and double resonance experiments in assigning the 1H resonances of valine and tyrosine residues of dihydrofolate reductase

AbstractSelective deuteration is a general solution to the resolution problem which limits the application of double resonance experiments to the assignment of the 1H NMR spectra of proteins. Spin-decoupling and NOE experiments have been carried out on Lactobacillus casei dihydrofolate reductase and on selectively deuterated derivatives of the enzyme containing either [γ-2H6]Val or (α,δ2,ϵ1-2H3]His, [α,δ1,δ2,ϵ1,ϵ2,ζ-2H6]Phe, [α,δ1,ϵ3,ζ2,ζ3,η2-2H6]Trp and [α,ϵ1,ϵ2-2H3]Tyr. When combined with ring-current shift calculations based on the crystal structure of the enzyme, these experiments allow us to assign 1H resonances of Val 61, Val 115, Tyr 46 and Tyr 68

The reaction between phosphorus trifluorideborane and ammonia : The synthesis of triamidophosphorus-borane,(NH2)3PBH3

The reaction of unstable phosphorus trifluoride-borane and ammonia yields the new, stable compound, (H2N)3PBH3.A formal analogy between BH3 and O is developed, and evidence is presented to indicate that the B---P bond is not broken during the ammonolysis of F3PBH3.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32370/1/0000445.pd

More is the Same; Phase Transitions and Mean Field Theories

This paper looks at the early theory of phase transitions. It considers a group of related concepts derived from condensed matter and statistical physics. The key technical ideas here go under the names of "singularity", "order parameter", "mean field theory", and "variational method". In a less technical vein, the question here is how can matter, ordinary matter, support a diversity of forms. We see this diversity each time we observe ice in contact with liquid water or see water vapor, "steam", come up from a pot of heated water. Different phases can be qualitatively different in that walking on ice is well within human capacity, but walking on liquid water is proverbially forbidden to ordinary humans. These differences have been apparent to humankind for millennia, but only brought within the domain of scientific understanding since the 1880s. A phase transition is a change from one behavior to another. A first order phase transition involves a discontinuous jump in a some statistical variable of the system. The discontinuous property is called the order parameter. Each phase transitions has its own order parameter that range over a tremendous variety of physical properties. These properties include the density of a liquid gas transition, the magnetization in a ferromagnet, the size of a connected cluster in a percolation transition, and a condensate wave function in a superfluid or superconductor. A continuous transition occurs when that jump approaches zero. This note is about statistical mechanics and the development of mean field theory as a basis for a partial understanding of this phenomenon.Comment: 25 pages, 6 figure

A Gravitational Aharonov-Bohm Effect, and its Connection to Parametric Oscillators and Gravitational Radiation

A thought experiment is proposed to demonstrate the existence of a gravitational, vector Aharonov-Bohm effect. A connection is made between the gravitational, vector Aharonov-Bohm effect and the principle of local gauge invariance for nonrelativistic quantum matter interacting with weak gravitational fields. The compensating vector fields that are necessitated by this local gauge principle are shown to be incorporated by the DeWitt minimal coupling rule. The nonrelativistic Hamiltonian for weak, time-independent fields interacting with quantum matter is then extended to time-dependent fields, and applied to problem of the interaction of radiation with macroscopically coherent quantum systems, including the problem of gravitational radiation interacting with superconductors. But first we examine the interaction of EM radiation with superconductors in a parametric oscillator consisting of a superconducting wire placed at the center of a high Q superconducting cavity driven by pump microwaves. We find that the threshold for parametric oscillation for EM microwave generation is much lower for the separated configuration than the unseparated one, which then leads to an observable dynamical Casimir effect. We speculate that a separated parametric oscillator for generating coherent GR microwaves could also be built.Comment: 25 pages, 5 figures, YA80 conference (Chapman University, 2012

A preliminary investigation of materialism and impulsiveness as predictors of technological addictions among young adults

Background and aims: The primary objective of the present research is to investigate the drivers of technological addiction in college students — heavy users of Information and Communication Technology (ICT). The study places cell phone and instant messaging addiction in the broader context of consumption pathologies, investigating the influence of materialism and impulsiveness on these two technologies. Clearly, cell phones serve more than just a utilitarian purpose. Cell phones are used in public and play a vital role in the lives of young adults. The accessibility of new technologies, like cell phones, which have the advantages of portability and an ever increasing array of functions, makes their over-use increasingly likely. Methods: College undergraduates (N = 191) from two U.S. universities completed a paper and pencil survey instrument during class. The questionnaire took approximately 15–20 minutes to complete and contained scales that measured materialism, impulsiveness, and mobile phone and instant messaging addiction. Results: Factor analysis supported the discriminant validity of Ehrenberg, Juckes, White and Walsh's (2008) Mobile Phone and Instant Messaging Addictive Tendencies Scale. The path model indicates that both materialism and impulsiveness impact the two addictive tendencies, and that materialism's direct impact on these addictions has a noticeably larger effect on cell phone use than instant messaging. Conclusions: The present study finds that materialism and impulsiveness drive both a dependence on cell phones and instant messaging. As Griffiths (2012) rightly warns, however, researchers must be aware that one's addiction may not simply be to the cell phone, but to a particular activity or function of the cell phone. The emergence of multi-function smart phones requires that research must dig beneath the technology being used to the activities that draw the user to the particular technology

Searches for very high energy gamma rays from blazars with CANGAROO-III telescope in 2005-2009

We have searched for very high energy (VHE) gamma rays from four blazars using the CANGAROO-III imaging atmospheric Cherenkov telescope. We report the results of the observations of H 2356-309, PKS 2155-304, PKS 0537-441, and 3C 279, performed from 2005 to 2009, applying a new analysis to suppress the effects of the position dependence of Cherenkov images in the field of view. No significant VHE gamma ray emission was detected from any of the four blazars. The GeV gamma-ray spectra of these objects were obtained by analyzing Fermi/LAT archival data. Non-simultaneous wide range (radio to VHE gamma-ray bands) spectral energy distributions (SEDs) including CANGAROO-III upper limits, GeV gamma-ray spectra, and archival data are discussed using a one-zone synchrotron self-Compton (SSC) model in combination with a external Compton (EC) radiation. The HBLs (H 2356-309 and PKS 2155-304) can be explained by a simple SSC model, and PKS 0537-441 and 3C 279 are well modeled by a combination of SSC and EC model. We find a consistency with the blazar sequence in terms of strength of magnetic field and component size.Comment: 11 pages, 8 figures, Accepted for publication in Astroparticle Physic

Lagrangian Curves in a 4-dimensional affine symplectic space

Lagrangian curves in R4 entertain intriguing relationships with second order deformation of plane curves under the special affine group and null curves in a 3-dimensional Lorentzian space form. We provide a natural affine symplectic frame for Lagrangian curves. It allows us to classify La- grangrian curves with constant symplectic curvatures, to construct a class of Lagrangian tori in R4 and determine Lagrangian geodesic

Effect of He implantation on the microstructure of zircaloy-4 studied using in situ TEM

Highlights • Differences in the evolution of α and βZr microstructures under 6 keV He ion implantation have been analysed as a function of irradiation dose and temperature using in situ TEM. • Both thermal and irradiation stabilities of Zr hydrides particles were studied and were found to dissolve with increasing fluence. • It is suggested that the combination of two different mass-transport mechanisms for He in zircaloy-4 play a major rule in the Zr hydride irradiation-induced dissolution. • He bubble lattices were observed to form during irradiation at 473 K and 1148 K in both crystalline phases, α and βZr, at around the same fluence of 1.7×10^17 ions⋅cm−2 (3.2 dpa)

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter