590 research outputs found
Spherical orbit closures in simple projective spaces and their normalizations
Let G be a simply connected semisimple algebraic group over an algebraically
closed field k of characteristic 0 and let V be a rational simple G-module of
finite dimension. If G/H \subset P(V) is a spherical orbit and if X is its
closure, then we describe the orbits of X and those of its normalization. If
moreover the wonderful completion of G/H is strict, then we give necessary and
sufficient combinatorial conditions so that the normalization morphism is a
homeomorphism. Such conditions are trivially fulfilled if G is simply laced or
if H is a symmetric subgroup.Comment: 24 pages, LaTeX. v4: Final version, to appear in Transformation
Groups. Simplified some proofs and corrected minor mistakes, added
references. v3: major changes due to a mistake in previous version
Regular functions on spherical nilpotent orbits in complex symmetric pairs: Exceptional cases
Given an exceptional simple complex algebraic group G and a symmetric pair (G, K), we study the spherical nilpotent K-orbit closures in the isotropy representation of K. We show that they are all normal except in one case in type G(2), and we compute the K-module structure of the ring of regular functions on their normalizations
Adsorption of phenol/tyrosol from aqueous solutions on macro-reticular aromatic and macro-porous polystyrene cross-linked with divinylbenzene polymeric resins
The current work aims at separating by adsorption of low-molecular-weight organic compounds in a
nanofiltration concentrate of the olive mill wastewaters. The experimental investigations on adsorption of
phenol/tyrosol in single and binary systems were conducted in batch mode by using the commercially
available macroporous resins FPX66 and MN202. The structures of such resins were examined by FTIR
before and after adsorption. The operating parameters affecting the adsorption process such as resin dosage,
contact time, pH, and initial concentration of phenol/tyrosol were investigated. Fast phenol and tyrosol uptakes
were observed for both resins. It can be attributed to their physical properties, for instance high specific area
and microporous area. The adsorption selectivity of phenol is larger than tyrosol when using FPX66 resin, but
smaller if MN202 resin is used. Acidic pH appeared to be always favourable for the adsorption. A synergetic
effect between solutes was observed since adsorption of phenol and tyrosol in the binary systems was faster
than the individual sorption of each solute. Five isotherms namely Langmuir, Freundlich, DubininRadushkevich,
Temkin and Redlich-Peterson were selected to fit the obtained equilibrium experimental data.
Finally, desorption of the examined compounds with ethanol (EtOH) allowed a maximum around 85 % of
phenol, and equal to 94 % of tyrosol on FPX66 and MN202 resins
Adsorption of phenol/tyrosol from aqueous solutions on macro-reticular aromatic and macro-porous polystyrene cross-linked with divinylbenzene polymeric resins
The current work aims at separating by adsorption of low-molecular-weight organic compounds in a
nanofiltration concentrate of the olive mill wastewaters. The experimental investigations on adsorption of
phenol/tyrosol in single and binary systems were conducted in batch mode by using the commercially
available macroporous resins FPX66 and MN202. The structures of such resins were examined by FTIR
before and after adsorption. The operating parameters affecting the adsorption process such as resin dosage,
contact time, pH, and initial concentration of phenol/tyrosol were investigated. Fast phenol and tyrosol uptakes
were observed for both resins. It can be attributed to their physical properties, for instance high specific area
and microporous area. The adsorption selectivity of phenol is larger than tyrosol when using FPX66 resin, but
smaller if MN202 resin is used. Acidic pH appeared to be always favourable for the adsorption. A synergetic
effect between solutes was observed since adsorption of phenol and tyrosol in the binary systems was faster
than the individual sorption of each solute. Five isotherms namely Langmuir, Freundlich, DubininRadushkevich,
Temkin and Redlich-Peterson were selected to fit the obtained equilibrium experimental data.
Finally, desorption of the examined compounds with ethanol (EtOH) allowed a maximum around 85 % of
phenol, and equal to 94 % of tyrosol on FPX66 and MN202 resins
A combinatorial smoothness criterion for spherical varieties
We suggest a combinatorial criterion for the smoothness of an arbitrary
spherical variety using the classification of multiplicity-free spaces,
generalizing an earlier result of Camus for spherical varieties of type .Comment: 14 pages, 2 table
In vitro ion chelating, antioxidative mechanism of extracts from fruits and barks of tetrapleura tetraptera and their protective effects against fenton mediated toxicity of metal ions on liver homogenates
The aim of the present study was to investigate the antioxidant activity and protective potential of T. tetraptera extracts against ion toxicity. The antioxidant activity of the extracts was investigated spectrophotometrically against several radicals (1,1-diphenyl-2-picrylhydrazyl (DPPH•), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS•), hydroxyl radical (HO•), and nitric oxide (NO•)), followed by the ferric reducing power, total phenols, flavonoid, and flavonol contents. The effects of the extracts on catalase (CAT), superoxide dismutase (SOD), and peroxidase activities were also determined using the standard methods as well as the polyphenol profile using HPLC. The results showed that the hydroethanolic extract of T. tetraptera (CFH) has the lowest ICvalue with the DPPH, ABTS, OH, and NO radicals. The same extract also exhibited the significantly higher level of total phenols (37.24 ± 2.00 CAE/g dried extract); flavonoids (11.36 ± 1.88 QE/g dried extract); and flavonols contents (3.95 ± 0.39 QE/g dried extract). The HPLC profile of T. tetraptera revealed that eugenol (958.81 ± 00 mg/g DW), quercetin (353.78 ± 00 mg/g DW), and rutin (210.54 ± 00 mg/g DW) were higher in the fruit than the bark extracts. In conclusion, extracts from T. tetraptera may act as a protector against oxidative mediated ion toxicity. © 2015 Bruno Moukette Moukette et al
Standard monomial theory for wonderful varieties
A general setting for a standard monomial theory on a multiset is introduced
and applied to the Cox ring of a wonderful variety. This gives a degeneration
result of the Cox ring to a multicone over a partial flag variety. Further, we
deduce that the Cox ring has rational singularities.Comment: v3: 20 pages, final version to appear on Algebras and Representation
Theory. The final publication is available at Springer via
http://dx.doi.org/10.1007/s10468-015-9586-z. v2: 20 pages, examples added in
Section 3 and in Section
Analisis Pengaruh Rx Level Terhadap Kecepatan Download Data Pada Teknologi GPRS Di PT XL Axiata Tbk. Purwokerto
Data transfer speed on GPRS\u27s technology isaffected by the present of some obstacles between sender\u27s side and recipient\u27s side. Those obstacles cause propagation loss that affect the reduction of power level value (rx level). The reduction will affect the data speed. The lower rx level\u27s value means the lower dataspeed. This researchwas done by doing drive test on BTS North Purwokerto and BTS Tambaksogra to measure the amount of power measured (Pr) andthe download data speed on GPRS\u27s network. The measuredpower level (Pr) was normalized to get rx level value. Regression analysis was done to get the relation between the download speed and the rx level value. Theanalysis has resulted in a model: download speed = 4.1 (rx level) 0.459 , with R^2 = 0.380. Correlation analysis shows high correlationbetween rx level and download speed (r = 0.608)
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