Exclusion Statistics of Quasiparticles in Condensed States of Composite Fermion Excitations

The exclusion statistics of quasiparticles is found at any level of the hierarchy of condensed states of composite fermion excitations (for which experimental indications have recently been found). The hierarchy of condensed states of excitations in boson Jain states is introduced and the statistics of quasiparticles is found. The quantum Hall states of charged $\alpha$-anyons ($\alpha$ -- the exclusion statistics parameter) can be described as incompressible states of $(\alpha+2p)$-anyons ($2p$ -- an even number).Comment: 4 page

Quantum Hall Spherical Systems: the Filling Fraction

Within the newly formulated composite fermion hierarchy the filling fraction of a spherical quantum Hall system is obtained when it can be expressed as an odd or even denominator fraction. A plot of $\nu\frac{2S}{N-1}$ as a function of $2S$ for a constant number of particles (up to N=10001) exhibits structure of the fractional quantum Hall effect. It is confirmed that $\nu_e +\nu_h=1$ for all particle-hole conjugate systems, except systems with $N_e =N_h$, and $N_e=N_h \pm 1$.Comment: 3 pages, Revtex, 7 PostScript figures, submitted to Phys. Rev. B Rapid Communicatio

Composite Fermions and the Half-Filled State

Under appropriate conditions electron-hole symmetry should apply to a partially filled Landau level of a two-dimensional electron gas. This suggests that the application of Jain’s composite fermion (CF) picture to either electrons or holes should lead to equivalent results. Surprisingly, for a system of Ne electrons on a Haldane sphere, this is not true for three values of the Landau level degeneracy 2S+1. When Ne-1\u3c~S\u3c~Ne, the sum of the electron filling factor ν and the hole filling factor μ, as determined from Jain’s picture, is smaller than unity. Because of this, use of the relation ν=1-μ can lead to “twin” or “alias” states having different values of ν for the same Ne and 2S+1. One example is the “half-filled” state. It is determined by requiring the effective (mean-field) flux 2S* “seen” by one CF to vanish. Different results are obtained when S*e=Se-(Ne-1) and S*h=S-(Nh-1) are set equal to zero. The same problem arises in the CF hierarchy picture when the number of quasielectrons nQE is related to the effective flux 2S* by 2(nQE-1)\u3c~2S*\u3c~2nQE

Meta-analysis and Meta-regression of Cognitive Behavioral Therapy for Psychosis (CBTp) Across Time: The Effectiveness of CBTp has Improved for Delusions

Published research shows small-to-medium effects of Cognitive Behavioral Therapy for Psychosis (CBTp) on reducing psychotic symptoms. Given the on-going development of CBTp interventions, the aim of this systematic review is to examine whether the effectiveness of CBTp has changed across time. MEDLINE, EMBASE, PsycINFO, and CENTRAL were searched for randomized controlled trials examining CBTp interventions targeting positive and/or negative symptoms vs treatment as usual. Four meta-analyses were carried out to examine the effectiveness of CBTp for: positive symptoms; delusions; hallucinations; and negative symptoms. Four meta-regressions examined whether the effectiveness of CBTp changed across time for these groups of symptoms. A total of 28 studies (n = 2698) yielded a pooled g of −0.24 (95% confidence interval [CI] −0.32, −0.16, P < .001) favoring CBTp for positive symptoms, with nonsignificant heterogeneity (Q = 26.87, P = .47; I2 =0%); 13 studies (n = 890) yielded a pooled g of −0.36 (95% CI −0.59, −0.13, P = .002) for delusions, with substantial heterogeneity (Q = 31.99, P = .001; I2 =62%); 16 studies (n = 849) yielded a pooled g of −0.26 (95% CI −0.42, −0.11, P < .001) for hallucinations, with nonsignificant heterogeneity (Q = 18.10, P = .26; I2 =17%); 19 studies (n = 1761) yielded a pooled g of −0.22 (95% CI −0.33, −0.12, P < .001) for negative symptoms, with nonsignificant heterogeneity (Q = 20.32, P = .32, I2 =11%). Meta-regressions indicated a significant effect of year on the effectiveness of CBTp only for delusions (F[1, 11] = 5.99, P = .032; R2 = 0.594); methodological quality did not effect this finding. Findings indicate small-to-medium effects of CBTp for psychotic symptoms, with increasing effectiveness across time for delusions

The Composite Fermion Hierarchy: Condensed States of Composite Fermion Excitations?

A composite Fermion hierarchy theory is constructed in a way related to the original Haldane picture by applying the composite Fermion (CF) transformation to quasiparticles of Jain states. It is shown that the Jain theory coincides with the Haldane hierarchy theory for principal CF fillings. Within the Fermi liquid approach for few electron systems on the sphere a simple interpretation of many-quasiparticle spectra is given and provides an explanation of failure of CF hierarchy picture when applied to the hierarchical $4/11$ state.Comment: 6 pages, Revtex, 4 figures in PostScript, submitted to Phys. Rev. Let

Mid-Infrared Ethane Emission on Neptune and Uranus

We report 8- to 13-micron spectral observations of Neptune and Uranus from the NASA Infrared Telescope Facility spanning more than a decade. The spectroscopic data indicate a steady increase in Neptune's mean atmospheric 12-micron ethane emission from 1985 to 2003, followed by a slight decrease in 2004. The simplest explanation for the intensity variation is an increase in stratospheric effective temperature from 155 +/- 3 K in 1985 to 176 +/- 3 K in 2003 (an average rate of 1.2 K/year), and subsequent decrease to 165 +/- 3 K in 2004. We also detected variation of the overall spectral structure of the ethane band, specifically an apparent absorption structure in the central portion of the band; this structure arises from coarse spectral sampling coupled with a non-uniform response function within the detector elements. We also report a probable direct detection of ethane emission on Uranus. The deduced peak mole fraction is approximately an order of magnitude higher than previous upper limits for Uranus. The model fit suggests an effective temperature of 114 +/- 3 K for the globally-averaged stratosphere of Uranus, which is consistent with recent measurements indicative of seasonal variation.Comment: Accepted for publication in ApJ. 16 pages, 10 figures, 2 table

Role of surface microgeometries on electron escape probability and secondary electron yield of metal surfaces

The influence of microgeometries on the Secondary Electron Yield (SEY) of surfaces is investigated. Laser written structures of different aspect ratio (height to width) on a copper surface tuned the SEY of the surface and reduced its value to less than unity. The aspect ratio of microstructures was methodically controlled by varying the laser parameters. The results obtained corroborate a recent theoretical model of SEY reduction as a function of the aspect ratio of microstructures. Nanostructures - which are formed inside the microstructures during the interaction with the laser beam - provided further reduction in SEY comparable to that obtained in the simulation of structures which were coated with an absorptive layer suppressing secondary electron emission

HD 145263: Spectral Observations of Silica Debris Disk Formation via Extreme Space Weathering?

We report here time domain infrared spectroscopy and optical photometry of the HD145263 silica-rich circumstellar disk system taken from 2003 through 2014. We find an F4V host star surrounded by a stable, massive 1e22 - 1e23 kg (M_Moon to M_Mars) dust disk. No disk gas was detected, and the primary star was seen rotating with a rapid ~1.75 day period. After resolving a problem with previously reported observations, we find the silica, Mg-olivine, and Fe-pyroxene mineralogy of the dust disk to be stable throughout, and very unusual compared to the ferromagnesian silicates typically found in primordial and debris disks. By comparison with mid-infrared spectral features of primitive solar system dust, we explore the possibility that HD 145263's circumstellar dust mineralogy occurred with preferential destruction of Fe-bearing olivines, metal sulfides, and water ice in an initially comet-like mineral mix and their replacement by Fe-bearing pyroxenes, amorphous pyroxene, and silica. We reject models based on vaporizing optical stellar megaflares, aqueous alteration, or giant hypervelocity impacts as unable to produce the observed mineralogy. Scenarios involving unusually high Si abundances are at odds with the normal stellar absorption near-infrared feature strengths for Mg, Fe, and Si. Models involving intense space weathering of a thin surface patina via moderate (T < 1300 K) heating and energetic ion sputtering due to a stellar superflare from the F4V primary are consistent with the observations. The space weathered patina should be reddened, contain copious amounts of nanophase Fe, and should be transient on timescales of decades unless replenished.Comment: 41 Pages, 5 Figures, 5 Tables, Accepted for publication in the Astrophysical Journa

Evolution from protoplanetary to debris discs: The transition disc around HD 166191

HD 166191 has been identified by several studies as hosting a rare and extremely bright warm debris disc with an additional outer cool disc component. However, an alternative interpretation is that the star hosts a disc that is currently in transition between a full gas disc and a largely gas-free debris disc. With the help of new optical to mid-IR spectra and Herschel imaging, we argue that the latter interpretation is supported in several ways: i) we show that HD 166191 is co-moving with the ~4 Myr-old Herbig Ae star HD 163296, suggesting that the two have the same age, ii) the disc spectrum of HD 166191 is well matched by a standard radiative transfer model of a gaseous protoplanetary disc with an inner hole, and iii) the HD 166191 mid-IR silicate feature is more consistent with similarly primordial objects. We note some potential issues with the debris disc interpretation that should be considered for such extreme objects, whose lifetime at the current brightness is mush shorter than the stellar age, or in the case of the outer component requires a mass comparable to the solid component of the Solar nebula. These aspects individually and collectively argue that HD 166191 is a 4-5 Myr old star that hosts a gaseous transition disc. Though it does not argue in favour of either scenario, we find strong evidence for 3-5 um disc variability. We place HD 166191 in context with discs at different evolutionary stages, showing that it is a potentially important object for understanding the protoplanetary to debris disc transition.Comment: accepted to MNRAS, fixed typos in abstract and axis labe