Reconnection of superfluid vortex bundles

Using the vortex filament model and the Gross Pitaevskii nonlinear Schroedinger equation, we show that bundles of quantised vortex lines in helium II are structurally robust and can reconnect with each other maintaining their identity. We discuss vortex stretching in superfluid turbulence and show that, during the bundle reconnection process, Kelvin waves of large amplitude are generated, in agreement with the finding that helicity is produced by nearly singular vortex interactions in classical Euler flows.Comment: 10 pages, 7 figure

Evaporation of a packet of quantized vorticity

A recent experiment has confirmed the existence of quantized turbulence in superfluid He3-B and suggested that turbulence is inhomogenous and spreads away from the region around the vibrating wire where it is created. To interpret the experiment we study numerically the diffusion of a packet of quantized vortex lines which is initially confined inside a small region of space. We find that reconnections fragment the packet into a gas of small vortex loops which fly away. We determine the time scale of the process and find that it is in order of magnitude agreement with the experiment.Comment: figure 1a,b,c and d, figure2, figure

Polarization of superfluid turbulence

We show that normal fluid eddies in turbulent helium II polarize the tangle of quantized vortex lines present in the flow, thus inducing superfluid vorticity patterns similar to the driving normal fluid eddies. We also show that the polarization is effective over the entire inertial range. The results help explain the surprising analogies between classical and superfluid turbulence which have been observed recently.Comment: 3 figure

The differential recruitment of executive functions during time, number and length perception: An individual differences approach.

Developmental, behavioural and neurological similarities in the processing of different magnitudes (time, number, space) support the existence of a common magnitude processing system (e.g. ATOM; Bueti & Walsh, 2009; Walsh, 2003). It is however unclear whether the recruitment of wider cognitive resources (STM and executive function) during magnitude processing is similar across magnitude domains or domain specific. The current study used an individual differences approach to examine the relationship between STM, executive function and magnitude processing. In two experiments, participants completed number, length and duration bisection tasks to assess magnitude processing and tasks which have been shown to assess STM span and the four key executive component processes identified by Miyake et al. (2000) and Fisk and Sharp (2004) (shifting, inhibition, updating and access). The results suggest that the recruitment of STM and executive resources differed for the different magnitude domains. Duration perception was associated with access, inhibition and STM span. Length processing was associated with updating and number processing was associated with access to semantic memory. For duration and length, greater difficulty in the magnitude judgement task resulted in more relationships to STM and executive function. It is suggested that duration perception may be more demanding of STM and executive resources because it is represented sequentially, unlike length and number which can be represented non-sequentially

Specific heat of the Kelvin modes in low temperature superfluid turbulence

It is pointed out that the specific heat of helical vortex line excitations, in low temperature superfluid turbulence experiments carried out in helium II, can be of the same order as the specific heat of the phononic quasiparticles. The ratio of Kelvin mode and phonon specific heats scales with L_0 T^{-5/2}, where L_0 represents the smoothed line length per volume within the vortex tangle, such that the contribution of the vortex mode specific heat should be observable for L_0 = 10^6-10^8 cm^{-2}, and at temperatures which are of order 1-10 mK.Comment: 3 pages, 1 figur

Finite temperature molecular dynamics study of unstable stacking fault free energies in silicon

We calculate the free energies of unstable stacking fault (USF) configurations on the glide and shuffle slip planes in silicon as a function of temperature, using the recently developed Environment Dependent Interatomic Potential (EDIP). We employ the molecular dynamics (MD) adiabatic switching method with appropriate periodic boundary conditions and restrictions to atomic motion that guarantee stability and include volume relaxation of the USF configurations perpendicular to the slip plane. Our MD results using the EDIP model agree fairly well with earlier first-principles estimates for the transition from shuffle to glide plane dominance as a function of temperature. We use these results to make contact to brittle-ductile transition models.Comment: 6 pages revtex, 4 figs, 16 refs, to appear in Phys. Rev.

Editorial

‘A new spring, and a new sound’, so begins a famous Dutch poem. Will the birds sing differently, as the poet wishes in the next line? BKI, now 178 years old—surely one of the longest-running journals of Southeast Asian studies in the world, and known around its original home, the KITLV (Royal Institute), as ‘the Old Dame’—starts 2022 with a remarkable new development. For this reason, the first issue of the year opens with an Editorial. After generations of sound and steady editing under the direction of two scholars, one in the role of Chief Editor and one as Managing Editor, from now on, BKI will be run by an expanded editorial team of seven scholars drawn both from the geographical region, Southeast Asia, and the disciplines in the humanities and social sciences that BKI is dedicated to examining..

Transduction by Phi Bb-1, a Bacteriophage of Borrelia Burgdorferi

We previously described a bacteriophage of the Lyme disease agent Borrelia burgdorferi designated phi BB-1. This phage packages the host complement of the 32-kb circular plasmids (cp32s), a group of homologous molecules found throughout the genus Borrelia. To demonstrate the ability of phi BB-1 to package and transduce DNA, a kanamycin resistance cassette was inserted into a cloned fragment of phage DNA, and the resulting construct was transformed into B. burgdorferi CA-11.2A cells. The kan cassette recombined into a resident cp32 and was stably maintained. The cp32 containing the kan cassette was packaged by phi BB-1 released from this B. burgdorferi strain. phi BB-1 has been used to transduce this antibiotic resistance marker into naive CA-11.2A cells, as well as two other strains of B. burgdorferi. This is the first direct evidence of a mechanism for lateral gene transfer in B. burgdorferi

Dielectric and absorbate effects on the optical properties of phosphazenes

The optical response of polyphosphazenes can be directly related to the {pi} (out-of-plane) and {pi}{prime} (in-plane) bonding interactions intrinsic to the electronic structure of these materials. Altering this structure either by hydrogen bonding or absorbate effects, affects both the linear and nonlinear optical susceptibilities. In this paper, we have performed electronic structure calculations on the cyclic molecules, P{sub 3}N{sub 3}(NHCH{sub 3}){sub 6}, P{sub 3}N{sub 3}(SCH{sub 3}){sub 6}, P{sub 3}N{sub 3}(OCH{sub 3}){sub 6} and P{sub 4}N{sub 4}(NHCH{sub 3}){sub 8} as model systems for the polymer. Charge distribution arguments are discussed to explain the influence of a polarizing electric field on the {pi} bonding systems, and are used to suggest methods to enhance their nonlinearities