A new proposal for the picture changing operators in the minimal pure spinor formalism

Using a new proposal for the ""picture lowering"" operators, we compute the tree level scattering amplitude in the minimal pure spinor formalism by performing the integration over the pure spinor space as a multidimensional Cauchy-type integral. The amplitude will be written in terms of the projective pure spinor variables, which turns out to be useful to relate rigorously the minimal and non-minimal versions of the pure spinor formalism. The natural language for relating these formalisms is the. Cech-Dolbeault isomorphism. Moreover, the Dolbeault cocycle corresponding to the tree-level scattering amplitude must be evaluated in SO(10)/SU(5) instead of the whole pure spinor space, which means that the origin is removed from this space. Also, the. Cech-Dolbeault language plays a key role for proving the invariance of the scattering amplitude under BRST, Lorentz and supersymmetry transformations, as well as the decoupling of unphysical states. We also relate the Green`s function for the massless scalar field in ten dimensions to the tree-level scattering amplitude and comment about the scattering amplitude at higher orders. In contrast with the traditional picture lowering operators, with our new proposal the tree level scattering amplitude is independent of the constant spinors introduced to define them and the BRST exact terms decouple without integrating over these constant spinors.

Notes on beta-deformations of the pure spinor superstring in AdS(5) x S(5)

We study the properties of the vertex operator for the beta-deformation of the superstring in AdS(5) x S(5) in the pure spinor formalism. We discuss the action of supersymmetry on the infinitesimal beta-deformation, the application of the homological perturbation theory, and the relation between the worldsheet description and the spacetime supergravity description. (C) 2011 Elsevier B.V. All rights reserved.

Quantum current algebra for the AdS(5) x S(5) superstring

The sigma model describing the dynamics of the superstring in the AdS(5) x S(5) background can be constructed using the coset PSU(2, 2 vertical bar 4)/SO(4, 1) x SO(5). A basic set of operators in this two dimensional conformal field theory is composed by the left invariant currents. Since these currents are not (anti) holomorphic, their OPE`s is not determined by symmetry principles and its computation should be performed perturbatively. Using the pure spinor sigma model for this background, we compute the one-loop correction to these OPE`s. We also compute the OPE`s of the left invariant currents with the energy momentum tensor at tree level and one loop.

Effect of fluoride-containing solutions on the surface of cast commercially pure titanium

This study evaluated the effects of fluoride-containing solutions on the surface of commercially pure titanium (CP Ti) obtained by casting. CP Ti specimens were fabricated and randomly assigned to 5 groups (n=10): group 1: stored in distilled water at 37 ± 1ºC; group 2: stored in distilled water at 37 ± 1ºC and daily immersed in 0.05% NaF for 3 min; group 3: stored in distilled water at 37 ± 1ºC and daily immersed in 0.2% NaF for 3 min; group 4: stored in distilled water at 37 ± 1ºC; and immersed in 0.05% NaF every 15 days for 3 min; and group 5: stored in distilled water at 37 ± 1ºC and immersed in 0.2% NaF every 15 days for 3 min. Surface roughness was measured with a profilometer immediately after metallographic polishing of the specimens (T0) and at 15-day intervals until completing 60 days of experiment (T15, T30, T45, T60). Data were analyzed statistically by ANOVA and Tukey's test (α=0.05). There was no statistically significant difference (p>0.05) in surface roughness among the solutions. In conclusion, fluoride-containing solutions (pH 7.0) used as mouthwashes do not damage the surface of cast CP Ti and can be used by patients with titanium-based restorations.

Comparative study of chemical and mechanical retentive systems for bonding of indirect composite resin to commercially pure titanium

This study evaluated the effect of chemical and mechanical surface treatments for cast metal alloys on the bond strength of an indirect composite resin (Artglass) to commercially pure titanium (cpTi). Thirty cylindrical metal rods (3 mm diameter x 60 mm long) were cast in grade-1 cpTi and randomly assigned to 6 groups (n=5) according to the received surface treatment: sandblasting; chemical treatment; mechanical treatment - 0.4 mm beads; mechanical treatment - 0.6 mm beads; chemical/mechanical treatment - 0.4 mm; and chemical/mechanical treatment - 0.6 mm beads. Artglass rings (6.0 mm diameter x 2.0 mm thick) were light cured around the cpTi rods, according manufacturer's specifications. The specimens were invested in hard gypsum and their bond strength (in MPa) to the rods was measured at fracture with a universal testing machine at a crosshead speed of 2.0 mm/min and 500 kgf load cell. Data were analyzed statistically by one-way ANOVA and Tukey test (a=5%). The surface treatments differed significantly from each other (p<0.05) regarding the recorded bond strengths. Chemical retention and sandblasting showed statistically similar results to each other (p=0.139) and both had significantly lower bond strengths (p<0.05) than the other treatments. In conclusion, mechanical retention, either associated or not to chemical treatment, provided higher bond strength of the indirect composite resin to cpTi.

Comparative study of two commercially pure titanium casting methods

The interest in using titanium to fabricate removable partial denture (RPD) frameworks has increased, but there are few studies evaluating the effects of casting methods on clasp behavior. OBJECTIVE: This study compared the occurrence of porosities and the retentive force of commercially pure titanium (CP Ti) and cobalt-chromium (Co-Cr) removable partial denture circumferential clasps cast by induction/centrifugation and plasma/vacuum-pressure. MATERIAL AND METHODS: 72 frameworks were cast from CP Ti (n=36) and Co-Cr alloy (n=36; control group). For each material, 18 frameworks were casted by electromagnetic induction and injected by centrifugation, whereas the other 18 were casted by plasma and injected by vacuum-pressure. For each casting method, three subgroups (n=6) were formed: 0.25 mm, 0.50 mm, and 0.75 mm undercuts. The specimens were radiographed and subjected to an insertion/removal test simulating 5 years of framework use. Data were analyzed by ANOVA and Tukey's to compare materials and cast methods (α=0.05). RESULTS: Three of 18 specimens of the induction/centrifugation group and 9 of 18 specimens of plasma/vacuum-pressure cast presented porosities, but only 1 and 7 specimens, respectively, were rejected for simulation test. For Co-Cr alloy, no defects were found. Comparing the casting methods, statistically significant differences (p<0.05) were observed only for the Co-Cr alloy with 0.25 mm and 0.50 mm undercuts. Significant differences were found for the 0.25 mm and 0.75 mm undercuts dependent on the material used. For the 0.50 mm undercut, significant differences were found when the materials were induction casted. CONCLUSION: Although both casting methods produced satisfactory CP Ti RPD frameworks, the occurrence of porosities was greater in the plasma/vacuum-pressure than in the induction/centrifugation method, the latter resulting in higher clasp rigidity, generating higher retention force values.

Storage effect on the acceptability of snacks made of pure amaranth and blends of amaranth and corn or chickpea

Snacks made by extrusion cooking of pure amaranth flour or mixtures of 80 per cent amaranth flour and 20 per centcorn grits or chickpea flour were developed to replace the traditional commercial ones with improved nutritional and functional quality. Pure amaranth snacks and the blended ones were flavored with salty and sweet flavors and evaluated for acceptability using a 9-point hedonic scale. The good acceptance observed for either salty or sweet flavored snacks indicated that they have characteristics to compete with similar commercial products. Acceptability of salty snacks increased with storage time at room temperature in BOPP (polypropylene bi-guided) packs whereas slightly decreased for the sweet ones. This type of storage proved to be very efficient for the conservation of the salty product and also suitable for the sweet ones

Intrahepatic Glissonian Approach for Pure Laparoscopic Left Hemihepatectomy

Background: Recent advances in laparoscopic devices and experience with advanced techniques have increased the indications for laparoscopic liver. Aim: The aim of this work was to present a video with technical aspects of a pure laparoscopic left hemi-hepatectomy (segments 2, 3, and 4) by using the intrahepatic Glissonian approach and control of venous outflow without hilar dissection or the Pringle maneuver. Patient and Method: A 63-year-old woman with a 5-cm solitary liver metastasis was referred for treatment. Four trocars were used. The left lobe was pulled upward and the lesser omentum was divided, exposing Arantius' ligament. This ligament is a useful landmark for the identification of the main left Glissonian pedicle. A small anterior incision was made in front of the hilum, and a large clamp was introduced behind the Arantius' ligament toward the anterior incision, allowing control of the left main sheath. Ischemic discoloration of the left liver was achieved and marked with cautery. The vascular clamp was replaced by a stapler. If ischemic delineation was coincident with a previously marked area, the stapler was fired. The left hepatic vein was dissected and encircled. Parenchymal transection and vascular control of the hepatic veins were accomplished with a Harmonic scalpel and an endoscopic stapling device, as appropriate. All these steps were performed without the Pringle maneuver and without hand assistance. Results: Operative time was 220 minutes with minimum blood loss. Hospital stay was 4 days. Pathology showed free surgical margins. The patient is alive with no signs of recurrence 18 months after the operation. Conclusion: Totally laparoscopic left hemihepatectomy is safe and feasible in selected patients and should be considered for patients with benign or malignant liver neoplasms. The described technique, with the use of the intrahepatic Glissonian approach and control of venous outflow, may facilitate laparoscopic left hemihepatectomy by reducing the technical difficulties in pedicle control and may decrease bleeding during liver transection.

Local atomic structure in tetragonal pure ZrO(2) nanopowders

The local atomic structures around the Zr atom of pure (undoped) ZrO(2) nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO(2) nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr-O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye-Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to the z direction; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments.

Evolutionary dynamics on rugged fitness landscapes: Exact dynamics and information theoretical aspects

The parallel mutation-selection evolutionary dynamics, in which mutation and replication are independent events, is solved exactly in the case that the Malthusian fitnesses associated to the genomes are described by the random energy model (REM) and by a ferromagnetic version of the REM. The solution method uses the mapping of the evolutionary dynamics into a quantum Ising chain in a transverse field and the Suzuki-Trotter formalism to calculate the transition probabilities between configurations at different times. We find that in the case of the REM landscape the dynamics can exhibit three distinct regimes: pure diffusion or stasis for short times, depending on the fitness of the initial configuration, and a spin-glass regime for large times. The dynamic transition between these dynamical regimes is marked by discontinuities in the mean-fitness as well as in the overlap with the initial reference sequence. The relaxation to equilibrium is described by an inverse time decay. In the ferromagnetic REM, we find in addition to these three regimes, a ferromagnetic regime where the overlap and the mean-fitness are frozen. In this case, the system relaxes to equilibrium in a finite time. The relevance of our results to information processing aspects of evolution is discussed.

A Procedure for Semantic Querying in the Adaptive Formalism

This paper contains a new proposal for the definition of the fundamental operation of query under the Adaptive Formalism, one capable of locating functional nuclei from descriptions of their semantics. To demonstrate the method`s applicability, an implementation of the query procedure constrained to a specific class of devices is shown, and its asymptotic computational complexity is discussed.

Structural and magnetic properties of pure and nickel doped SnO(2) nanoparticles

Ni-doped SnO(2) nanoparticles prepared by a polymer precursor method have been characterized structurally and magnetically. Ni doping (up to 10 mol%) does not significantly affect the crystalline structure of SnO(2), but stabilizes smaller particles as the Ni content is increased. A notable solid solution regime up to similar to 3 mol% of Ni, and a Ni surface enrichment for the higher Ni contents are found. The room temperature ferromagnetism with saturation magnetization (MS) similar to 1.2 x 10(-3) emu g(-1) and coercive field (H(C)) similar to 40 Oe is determined for the undoped sample, which is associated with the exchange coupling of the spins of electrons trapped in oxygen vacancies, mainly located on the surface of the particles. This ferromagnetism is enhanced as the Ni content increases up to similar to 3 mol%, where the Ni ions are distributed in a solid solution. Above this Ni content, the ferromagnetism rapidly decays and a paramagnetic behavior is observed. This finding is assigned to the increasing segregation of Ni ions (likely formed by interstitials Ni ions and nearby substitutional sites) on the particle surface, which modifies the magnetic behavior by reducing the available oxygen vacancies and/or the free electrons and favoring paramagnetic behavior.

Chemical characterization and anticorrosion properties of corrosion products formed on pure copper in synthetic rainwater of Rio de Janeiro and Sao Paulo

This work aims to characterize corrosion products formed on copper samples exposed to synthetic rainwater of Rio Janeiro and Sao Paulo. XRD and XPS were employed to determine their composition, while electrochemical techniques were used to evaluate their protective properties. XRD and XPS indicated the thickening of the corrosion layer with time. Electrochemical results showed that the protectiveness of the corrosion layer depends on the solution composition. Based on our findings a corrosion mechanism for copper in simulated rainwater is proposed where the role of NH(4)(+) ions in the cuprite layer partial regeneration is taken into account. (C) 2009 Elsevier Ltd. All rights reserved.

Synthesis of Cyclic Guanidine Intermediates of Anatoxin-a(s) in Both Racemic and Enantiomerically Pure Forms

The alkyl chain of anatoxin-a(s) (cyclic guanidines), which can be used as an intermediate in the total synthesis of anatoxin-a(s), was synthesized in both racemic and enantiomerically pure forms. These enantiomerically pure cyclic compounds can be used as chiral inductors in some reactions. The two racemic routes disclosed herein have the advantages of high overall yield and mild reaction conditions. Both routes proceed through an intermediate 2,3-diaminoacid - an important synthetic scaffold - with good yields. Furthermore, the N,N-dimethyl-2(tosylimino)imidazolidine-4-carboxamide might be obtained from 2-(tosylimino)imidazolidine-4-carboxylic acid followed by selective reduction of the carbonyl functionality. All synthesized compounds were analyzed by mass spectrometry and (1)H NMR and (13)C NMR spectroscopy.

Growth and acidification performance of probiotics in pure culture and co-culture with Streptococcus thermophilus: The effect of inulin

Inulin was used as a prebiotic to improve the quality and consistency of skim milk fermented by co-cultures and pure Cultures of Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus bulgaricus and Bifidobacterium lactis with Streptococcus thermophilus. We compared, either in the presence or absence of 4 g inulin/100 g, the results of the main kinetic parameters, specifically the generation time (t(g)), the maximum acidification rate (V(max)). and the times to reach V(max) (t(max)), to attain pH 5.0 (t(pH5.0)) and to complete the fermentation (t(pH4.5)). Post-acidification, lactic acid formation and cell counts were also determined and compared, either 1 day after the fermentation was complete or after 7 day storage at 4 degrees C. In general, inulin addition to the milk increased in co-cultures V(max), decreased t(max), t(g) and t(pH4.5), favored post-acidification, exerted a bifidogenic effect, and preserved almost intact cell viability during storage. In addition, S. thermophilus was shown to stimulate the metabolism of the other lactic bacteria. Contrary to co-cultures, most of the effects in pure Cultures were not statistically significant. The most important aspect of this paper is the use of the generation time as a toot to investigate the microbial response to inulin addition. (c) 2009 Elsevier Ltd. All rights reserved.