Values of the Pukánszky invariant in McDuff factors

In 1960 Pukánszky introduced an invariant associating to every masa in a separable II<sub>1</sub> factor a non-empty subset of the N ∪ {∞}. This invariant examines the multiplicity structure of the von Neumann algebra generated by the left-right action of the masa. In this paper it is shown that any non-empty subset of the N ∪ {∞} arises as the Pukánszky invariant of some masa in a separable McDuff II<sub>1</sub> factor containing a masa with Pukánszky invariant {1}. In particular the hyperfinite II<sub>1</sub> factor and all separable McDuff II<sub>1</sub> factors with a Cartan masa satisfy this hypothesis. In a general separable McDuff II<sub>1</sub> factor we show that every subset of the N ∪ {∞} containing ∞ is obtained as a Pukánszky invariant of some masa

Strong singularity of singular masas in II₁ factors

A singular masa A in a II1 factor N is defined by the property that any unitary w ∈ N for which A=wAw* must lie in A. A strongly singular masa A is one that satisfies the inequality ||EA- EwAw*||∞,2 ≥||w- EA(w)||2 for all unitaries w ∈ N where EA is the conditional expectation of N onto A, and ||⋅||∞,2 is defined for bounded maps Φ : N → N by sup{||Φ (x)||2:x ∈ N,||x||≤1}. Strong singularity easily implies singularity, and the main result of this paper shows the reverse implication

Water vole (Arvicola amphibius) abundance in grassland habitats of Glasgow

Water vole (Arvicola amphibius) populations have undergone a serious decline throughout the UK, and yet a stronghold of these small mammals is found in the greater Easterhouse area of Glasgow. The water voles in this location are mostly fossorial, living a largely subterranean existence in grasslands, rather than the more typical semi-aquatic lifestyle in riparian habitats. In this study, we carried out capture-mark-recapture surveys on water voles at two sites: Cranhill Park and Tillycairn Drive. We made a total of 62 captures including retraps, and the resulting population estimates were 78 individuals (95% confidence interval 41-197) for Cranhill Park and 42 individuals (20-141) for Tillycairn Drive. From these figures we estimated a population density of water voles, which appeared to be higher than other reports from the UK. Despite the difficulties of sampling in urban environments that resulted in relatively low capture rates, our data suggest that the greater Easterhouse area of Glasgow holds water voles at relatively high population densities. These results will inform future conservation in the City of Glasgow and surrounding areas, as well as raise awareness of important water vole populations in urban environments

Is silt the most influential soil grain size fraction?

The contribution of individual grain size fractions (2000–500, 500–250, 250–63, 63–2 and < 2 μm) to bulk soil surface area and reactivity is discussed with reference to mineralogical and oxalate and dithionite extractions data. The 63–2 μm fraction contributed up to 56% and 67% of bulk soil volume and BET surface area, respectively. Consideration of these observations and the mineralogy of this fraction suggest that the 63–2 μm fraction may be the most influential for the release of elements via mineral dissolution in the bulk soil

Ground State Properties of the Doped 3-Leg t-J Ladder

Results for a doped 3-leg t-J ladder obtained using the density matrix renormalization group are reported. At low hole doping, the holes form a dilute gas with a uniform density. The momentum occupation of the odd band shows a sharp decrease at a large value of k_F similar to the behavior of a lightly doped t-J chain, while the even modes appear gapped. The spin-spin correlations decay as a power law consistent with the absence of a spin gap, but the pair field correlations are negligible. At larger doping we find evidence for a spin gap and as x increases further we find 3-hole diagonal domain walls. In this regime there are pair field correlations and the internal pair orbital has d_x^2-y^2 - like symmetry. However, the pair field correlations appear to fall exponentially at large distances.Comment: 14 pages, 11 postscript figure

The impact of parent-created motivational climate on adolescent athletes' perceptions of physical self-concept

This is a preliminary version of this article. The official published version can be obtained from the link below.Grounded in expectancy-value model (Eccles, 1993) and achievement goal theory (Nicholls, 1989), this study examined the perceived parental climate and its impact on athletes' perceptions of competence and ability. Hierarchical regression analyses with a sample of 237 British adolescent athletes revealed that mothers and fathers' task- and ego-involving climate predicted their son's physical self-concept; the father in particular is the strongest influence in shaping a son's physical self-concept positively and negatively. It was also found that the self-concept of the young adolescent athlete is more strongly affected by the perceived parental-created motivational climate (both task and ego) than the older adolescent athlete's self-concept. These findings support the expectancy-value model assumptions related to the role of parents as important socializing agents, the existence of gender-stereotyping, and the heavy reliance younger children place on parents' feedback

Effects of domain walls on hole motion in the two-dimensional t-J model at finite temperature

The t-J model on the square lattice, close to the t-J_z limit, is studied by quantum Monte Carlo techniques at finite temperature and in the underdoped regime. A variant of the Hoshen-Koppelman algorithm was implemented to identify the antiferromagnetic domains on each Trotter slice. The results show that the model presents at high enough temperature finite antiferromagnetic (AF) domains which collapse at lower temperatures into a single ordered AF state. While there are domains, holes would tend to preferentially move along the domain walls. In this case, there are indications of hole pairing starting at a relatively high temperature. At lower temperatures, when the whole system becomes essentially fully AF ordered, at least in finite clusters, holes would likely tend to move within phase separated regions. The crossover between both states moves down in temperature as doping increases and/or as the off-diagonal exchange increases. The possibility of hole motion along AF domain walls at zero temperature in the fully isotropic t-J is discussed.Comment: final version, to appear in Physical Review

Giant Coulomb broadening and Raman lasing on ionic transitions

CW generation of anti-Stokes Raman laser on a number of blue-green argon-ion lines (4p-4s, 4p-3d) has been demonstrated with optical pumping from metastable levels 3d'^2G, 3d^4F. It is found, that the population transfer rate is increased by a factor of 3-5 (and hence, the output power of such Raman laser) owing to Coulomb diffusion in the velocity space. Measured are the excitation and relaxation rates for the metastable level. The Bennett hole on the metastable level has been recorded using the probe field technique. It has been shown that the Coulomb diffusion changes shape of the contour to exponential cusp profile while its width becomes 100 times the Lorentzian one and reaches values close to the Doppler width. Such a giant broadening is also confirmed by the shape of the absorption saturation curve.Comment: RevTex 18 pages, 5 figure

Designing a 2D RZ Venture Model for Neutronic Analysis of the Nigeria Research Reactor-1 (NIRR-1)

A 2D RZ VENTURE model has been developed for the Nigeria Research Reactor-1 (NIRR-1) and this model was used to perform neutronic analysis for the system using the code “VENTURE-PC”. The major homogenized regions in the 2D VENTURE model include the active fuel region and the control region while the remaining components in the system geometry where modelled as closely as possible. The reactor physics parameters generated from the neutronic calculations include excess reactivity, control rod worth, shim worth, shutdown margin. The model predictions of these parameters for NIRR-1 system were in good agreement with experimental results as well as the results from similar calculations using different nuclear analysis tools. This 2D RZ VENTURE model gives an excellent simulation of the Nigeria Research Reactor-1 and the model will be very helpful in the future analysis of the system, as well for developing an LEU core model for future conversion of NIRR-1 from HEU to LEU fuelled research reactor. Keywords: Model, Neutronics, geometry, code, Design, Reactor, Simulation, Calculations, NIRR-1, Shim, Control, Shutdown, Physics. Peak, Density, Power, Flux, Neutro