Condensation temperature of interacting Bose gases with and without disorder

The momentum-shell renormalization group (RG) is used to study the condensation of interacting Bose gases without and with disorder. First of all, for the homogeneous disorder-free Bose gas the interaction-induced shifts in the critical temperature and chemical potential are determined up to second order in the scattering length. The approach does not make use of dimensional reduction and is thus independent of previous derivations. Secondly, the RG is used together with the replica method to study the interacting Bose gas with delta-correlated disorder. The flow equations are derived and found to reduce, in the high-temperature limit, to the RG equations of the classical Landau-Ginzburg model with random-exchange defects. The random fixed point is used to calculate the condensation temperature under the combined influence of particle interactions and disorder.Comment: 7 pages, 2 figure

Wilsonian Proof for Renormalizability of N=1/2 Supersymmetric Field Theories

We provide Wilsonian proof for renormalizability of four-dimensional quantum field theories with ${\cal N}=1/2$ supersymmetry. We argue that the non-hermiticity inherent to these theories permits assigning noncanonical scaling dimension both for the Grassman coordinates and superfields. This reassignment can be done in such a way that the non(anti)commutativity parameter is dimensionless, and then the rest of the proof ammounts to power counting. The renormalizability is also stable against adding standard four-dimensional soft-breaking terms to the theory. However, with the new scaling dimension assignments, some of these terms are not just relevant deformations of the theory but become marginal.Comment: 10 pages, no figure, v2: minor correctio

Temperature dependent band structure of the Kondo insulator

We present a Qantum Monte Carlo (QMC) study of the temperature dependent dynamics of the Kondo insulator. Working at the so-called symmetrical point allows to perform minus-sign free QMC simulations and thus reach temperatures of less than 1% of the conduction electron bandwidth. Study of the temperature dependence of the single particle Green's function and dynamical spin correlation function shows a surprisingly intricate low temperature band structure and gives evidence for two characteristic temperatures, which we identify with the Kondo and coherence temperature, respectively. In particular, the data show a temperature induced metal-insulator transition at the coherence temperature.Comment: RevTex-file, 4 PRB pages with 4 eps figures. Hardcopies of figures (or the entire manuscript) can be obtained by e-mail request to: [email protected]

Electrophoretic Deposition of TiO2 Thin Films for Photocatalytic Degradation of Organic Pollutants in Water

In this study, electrophoretic deposition (EPD) technique was used to deposit titanium dioxide (TiO2) thin films on conducting glass substrates for application in photocatalytic degradation of organic pollutants in water. Phenol was used as a model pollutant. The EPD suspension related parameters and deposition conditions were first optimized for good quality film deposits. The suspension stability and deposition conditions that result in good adherence of TiO2 particles to the substrate with homogeneous film coatings  are ethanol, a TiO2 solid loading of 4 wt%, a 0.2 wt% iodine concentration in the solvent and a deposition voltage of 20 V in a time of 3.5 minutes. The photocatalytic activity of TiO2 thin films decreased exponentially with the ultraviolet light (UV) illumination time and it was also dependent on film thickness, and sintering temperature of the TiO2 thin films. Highest rate of photocatalytic activity was observed at an optimal film thickness of 95 ± 2 µm sintered at 300 °C. The implications of these results are discussed for design of inexpensive wastewater purification systems for light industries as well for semi urban small communities.Keywords: Electrophoretic deposition; Titanium dioxid

Evaluation De L’activité Acaricide De Quelques Biopesticides Sur L’acarien Tarsonème, Polyphagotarsonemus Latus Banks (Acari : Tarsonemidae) Infestant L’aubergine Gboma (Solanum Macrocarpon L.) Au Sud-Bénin

L’acarien tarsonème, Polyphagotarsonemus latus Banks, est un important ravageur de l’aubergine Gboma (Solanum macrocarpon L.), un légume-feuille de grande consommation au Bénin. La gestion de ce ravageur repose fondamentalement sur la lutte chimique avec toutes ses conséquences sur la santé et sur l’environnement ; d’où la nécessité de rechercher des solutions alternatives. Ainsi, la performance de trois biopesticides notamment huile de neem (Azadirachta indica A. Juss), extraits aqueux de hyptis (Hyptis suaveolens (L.) Poit, et du faux basilic (Ocimum gratissimum L), a été testée sur les œufs et adultes de P. latus au laboratoire de paires avec celle de Acarius et Sunpyrifos, deux acaricides chimiques communément utilisés au Bénin. Aussi, leurs effets sur les densités de population du ravageur et la productivité du Gboma ont-ils été évalués en plein champ. Au laboratoire, les taux moyens d’éclosion des œufs ont varié significativement entre traitements, allant 36 ± 5% à 80 ± 5% (P < 0,0001). Le plus fort taux d’éclosion a été enregistré sur le témoin et hyptis tandis que le plus fort d’éclosion a été enregistré avec Acarius suivi du Sunpyrifos et de l’huile de neem. Les taux de mortalité des adultes de P. latus ont également varié significativement entre les différents traitements allant de 43 ± 2% à 100% (P < 0,0001). Les plus faibles mortalités ont été enregistrées sur le témoin suivi de hyptis tandis que les plus forts taux ont été enregistrés, avec les doubles-doses de Acarius, Sunpyrifos et de l’huile de neem. Au champ, les densités moyennes par feuille des stades mobiles de P. latus ont varié significativement entre traitements, allant de 5,37 ± 0,59 et 2,71 ± 0,37 individus (P < 0,0001) ; les densités les plus fortes ayant été enregistrées sur le témoin tandis qu’aucune différence statistique n’a été observée entre les cinq autres traitements. Les plus fortes productivités de Gboma (kg/4 m2 ) ont été enregistrées avec l’huile de neem (13,65 ± 2,13), Sunpyrifos (11,10 ± 1,66) et Acarius (10,76 ± 1,32). Il s’en déduit qu’en attendant des études complémentaires, l’huile de neem peut être recommandée comme alternative aux acaricides chimiques contre P. latus sur les parcelles de Gboma au Sud-Bénin. The broad mite, Polyphagotarsonemus latus Banks is a key pest of the nightshade, commonly called Gboma eggplant (Solanum macrocarpon L.), a staple leafy vegetable in Benin. Management of this pest relies on chemical control despite its harmful environmental and sanitary impacts. It urgestherefore to search for alternative methods. In that respect, performances of some biopesticides including neem oil (Azadirachta indica A. Juss), aqueous extracts of Hyptis suaveolens (L.) Poit and of Ocimum gratissimum L. (clove basil), were tested on egg and adult stages of P. latus in laboratory in comparison to those of Acarius and Sunpyrifos, two chemical acaricides commonly used on vegetable farms in Southern Benin. In addition, their effects on the population densities of the pest and on the productivity of Gboma were evaluated in the field. In the laboratory, mean egg hatching rates varied significantly among treatments, ranging from 36 ± 5% to 80 ± 5% (P < 0,0001). The highest hatching rates were recorded with the control and hyptis treatments whereas the lowest hatching rates were recorded with Acarius followed by Sunpyrifos then neem oil treatments. Mortality rates of adult P. latus individuals also varied significantly among treatments, ranging from 43 ± 2% to 100% (P < 0,0001). The lowest mortality rates were recorded on the control followed by hyptis treatments whereas the highest mortalities were recorded with the double-doses of Acarius, Sunpyrifos and neem oil. In the field trials, mean densities of mobile stages of P. latus varied significantly among treatments, ranging from 5,37 ± 0,59 to 2,71 ± 0,37 individus (P < 0,0001). The highest densities were recorded on the control treatment whereas no significant differences were observed among the five other treatmentsThe highest productivities in fresh Gboma leaves on 4 m2 plot were recorded with neem oil (13.65 ± 2.13 kg), Sunpyrifos (11.1 ± 1.66 kg) and Acarius (10.76 ± 1.32 kg). Pending further studies, neem oil may be recommended as an alternative to chemical acaricides for the control of P. latus on Gboma plots in Southern Benin

The Coherent Radio Emission from the RS CVn Binary HR 1099

We used the Australia Telescope in March-April 2005 to observe the RS CVn binary HR 1099 at 1.384 and 2.368 GHz at two epochs, each of 9 h in duration and 11 days apart. During two episodes of coherent emission, we employed a recently installed facility to sample the data at 78 ms intervals to measure the fine temporal and spectral structure of HR 1099. Our main observational results include: ~100% left hand circularly polarised emission was seen at both 1.384 and 2.368 GHz during both epochs; in the first event the emission feature drifted across the spectrum; three 22 min integrations made at 78 ms time resolution showed that the modulation index of the Stokes V parameter increased monotonically as the integration time was decreased and was still increasing at our resolution limit; we believe that the highly polarised emission is due to electron-cyclotron maser emission (ECME) operating in the corona of one of the binary components. We discuss two kinds of maser sources that may be responsible for driving the observed events. We suggest that the ECME source may be an aurora-like phenomenon due to the transfer of plasma from the K2 subgiant to the G5 dwarf in a strong stellar wind.Comment: Accepted for publication in the Publications of the Astronomical Society of Australi

Connectedness and local connectedness of topological groups and extensions

summary:It is shown that both the free topological group $F(X)$ and the free Abelian topological group $A(X)$ on a connected locally connected space $X$ are locally connected. For the Graev's modification of the groups $F(X)$ and $A(X)$, the corresponding result is more symmetric: the groups $F\Gamma(X)$ and $A\Gamma(X)$ are connected and locally connected if $X$ is. However, the free (Abelian) totally bounded group $FTB(X)$ (resp., $ATB(X)$) is not locally connected no matter how ``good'' a space $X$ is. The above results imply that every non-trivial continuous homomorphism of $A(X)$ to the additive group of reals, with $X$ connected and locally connected, is open. We also prove that any dense in itself subspace of the Sorgenfrey line has a Urysohn connectification. If $D$ is a dense subset of $\{0,1\}^{\frak c}$ of power less than $\frak c$, then $D$ has a Urysohn connectification of the same cardinality as $D$. We also strengthen a result of [1] for second countable Tychonoff spaces without open compact subspaces proving that it is possible to find a compact metrizable connectification of such a space preserving its dimension if it is positive