Pion interactions in the X(3872)

We consider pion interactions in an effective field theory of the narrow resonance X(3872), assuming it is a weakly bound molecule of the charm mesons D-0(D) over bar (*0) and D-*0(D) over bar (0). Since the hyperfine splitting of the D-0 and D-*0 is only 7 MeV greater than the neutral pion mass, pions can be produced near threshold and are nonrelativistic. We show that pion exchange can be treated in perturbation theory and calculate the next-to-leading-order correction to the partial decay width Gamma[X -> D-0(D) over bar (0)pi(0)].

BEHAVIOR OF THE ANION-RADICALS ELECTROCHEMICALLY GENERATED IN THE REDUCTION OF NOSYL AMIDES

The behaviour of nitrobenzenesulfonamide anion radicals generated from the electrochemical reduction of aliphatic and aromatic amines protected by nitrobenzenesulfonyl (nosyl) groups in N,N-' dimethylformamide has been reported. The species have been characterized by voltammetry and optical and electron spin resonance spectroscopies. The visible spectra of the anion radicals were recorded and the hyperfine splitting constants were assigned to specific proton positions and nitrogen nuclei of the molecule. The stabilities of the anion radicals are affected by electronic properties of the protecting group and specific features of the amines, which show direct influence on the route of cathodic cleavage of the nitrobenzenesulfonamides.

Hyperfine interaction in Zn-Al layered double hydroxides intercalated with conducting polymers

Organic-inorganic hybrid materials based on the assembly between inorganic 2D host structure and polymer have received considerable attention in the last few years. This emerging class of materials presents several applications according to their structural and functional properties. Particularly, among others, layered double hydroxides (LDHs) provide the opportunity of preparing new organically modified 2D nanocomposites. Pyrrole carboxylic acid derivatives, namely 4-(lH-pyrrol-1-yl)benzoate, 3-(pyrrol-i-yl)-propanoate,7-(pyrrol-1-yl)-heptanoate, and aniline carboxylic acid derivative, namely 3-aminobenzoic acid, have been intercalated in LDHs of intralamellar composition Zn2Al(OH)(6). The LDHs were synthesized by the co-precipitation method at constant pH followed by hydrothermal treatment for 72 h. The materials were characterized by powder X-ray diffraction patterns (PXRD), transmission electron microscopy (TEM) thermogravimetric analysis (TGA), and electron spin resonance (ESR). The basal spacing found by the PXRD technique gives evidence of the formation of bilayers of the intercalated anions. ESR spectra present a typical signal with a superhyperfine structure with 6 + 1 lines (g = 2.005 +/- 0.0004), which is assigned to the interaction between a carboxylate radical from the guest molecules and a nearby aluminium nucleus (I = 5/2) from the host structure. Additionally, the ESR data suggest that the monomers are connected to each other in limited number after thermal treatment. (c) 2007 Elsevier Ltd. All rights reserved.

Fertility life table of Trichogramma pretiosum and Trichogramma acacioi (Hymenoptera : Trichogrammatidae) on Sitotroga cerealella (Lepidoptera : Gelechiidae) eggs at different constant temperatures

Fertility life tables were developed for both Trichogramma pretiosum and Trichogramma acacioi reared on Sitotroga cerealella eggs as an alternative host at five different temperatures. The egg parasitoids were first collected from Nipteria panacea eggs, a lepidopterous pest of avocado. Egg parasitoid females were individualized in small glass vials along with 40 eggs of the host during 24 h for parasitization. For evaluation of the parasitism capacity, a similar procedure was adopted, but cardboards with eggs were replaced every day. The net reproductive rate (Ro), intrinsic rate of increase (rm), finite rate of increase (lambda), and mean generation time (T) were estimated. Temperature affected all parameters for both Trichogramma species. The highest fecundity for both species was observed at 25degreesC. Extreme temperatures such as 15degreesC or 35degreesC negatively affect the development rate of both species.

Application of the Potentiometric Stripping Analysis with Constant Current for the Determination of Lithium Ions Using a Spinel-Type Manganese (IV) Oxide-Modified Carbon Paste Electrode

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Two-branes with variable tension model and the effective Newtonian constant

It is shown that, in the two brane time variation model framework, if the hidden brane tension varies according to the phenomenological Eotvos law, the visible brane tension behavior is such that its time derivative is negative in the past and positive after a specific time of cosmological evolution. This behavior is interpreted in terms of a useful mechanical system analog and its relation with the variation of the Newtonian (effective) gravitational constant is explored.

DC Electric Field Dependence of the Dielectric Constant of Pzt Thin Films Prepared by Polymeric Precursor Method

This work reports dielectric measurements performed on Pb(Zr0.53Ti0.47)O3 (PZT) thin films prepared by a polymeric precursor method. The -E curves obtained for the PZT film measured at 100 kHz, under a small ac 0.2 kV/cm signal-test and a dc scan featured a typical butterfly curve. However, the -E curves obtained for PZT film under a dc scan, with a scan rate of 0.003 V/s, shows a pronounced asymmetry. The absence of a symmetric secondary peak in -E curves could be an indication of essentially 180 domain switching.

Non-Zeeman splitting for a spin-resolved STM with a Kondo adatom in a spin-polarized two-dimensional electron gas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Physiologic and productive responses of Holstein dairy cows with access to the constant or limited shade

The work: was carried out to evaluate the physiologic and productive responses of 16 Holstein breed cows, in different lactating stages and production levels, maintained in two free stall corral types, with or without plastic sheet covering, in the southeast-northwest of the covered area edges. The animals were confined in free stall system, during the months of the summer, with access to the constant or Limited shade. A complete randomized experimental design was: used. The physiological variables measured were respiratory frequency (morning an afternoon) and rectal temperature (morning and afternoon). The productive variables were milk production (morning, afternoon and daily), dry matter (DM) intake (% live weight) and efficiency of milk production (kg of milk/kg DM intake). The animals with access to the constant shade presented respiratory frequency (74.1 vs 81.0 breath/min.) and rectal temperature (39.5 vs 39.7 degrees C) lower and mirk production (22.6 vs 20.9 kg/day) and efficiency of milk production (1.3 vs 1.2 kg of milk/kg DM ingested) higher than the animals with access to the limited shade. There was no effect on the dry matter intake.

The effect of changes in the bulk dielectric constant on the DNA torsional properties

The effect of changes in the bulk dielectric constant on the DNA torsional properties was evaluated from plasmid circularization reactions. In these reactions, pUC18 previously linearized by EcoRI digestion was recircularized with T4 DNA ligase. The bulk dielectric constant of the reaction medium was decreased by the addition of different concentrations of neutral solutes: ethylene glycol, glycerol, sorbitol, and sucrose, or increased by the addition of glycine. The topoisomers generated by the ligase reaction were resolved by agarose-gel electrophoresis. The DNA twist energy parameter (K), which is an apparent torsional constant, was determined by linearization of the Gaussian topoisomers' distribution. It was observed that the twist energy parameter for the given solutes is almost linearly dependent on the bulk dielectric constant. In the reaction buffer, the twist energy parameter was determined to be 1100 +/- 100. By decreasing the dielectric constant to 74 with the addition of sorbitol, the value of the parameter reaches K = 900 +/- 100, whereas the addition of ethylene glycol leads to kappa = 400 +/- 50. Upon addition of glycine, which resulted in a dielectric constant equal to 91, the value of the twist energy parameter increased to K 1750 +/- 100. (c) 2007 Wiley Periodicals.

Kinematics of a spacetime with an infinite cosmological constant

A solution of the sourceless Einstein's equation with an infinite value for the cosmological constant L is discussed by using Inonu-Wigner contractions of the de Sitter groups and spaces. When Lambda --> infinity, spacetime becomes a four-dimensional cone, dual to Minkowski space by a spacetime inversion. This inversion relates the four-cone vertex to the infinity of Minkowski space, and the four-cone infinity to the Minkowski light-cone. The non-relativistic limit c --> infinity. is further considered, the kinematical group in this case being a modified Galilei group in which the space and time translations are replaced by the non-relativistic limits of the corresponding proper conformal transformations. This group presents the same abstract Lie algebra as the Galilei group and can be named the conformal Galilei group. The results may be of interest to the early Universe Cosmology.

Freezing of the QCD coupling constant and the pion form factor

The possibility that the QCD coupling constant (alpha(s)) has an infrared finite behavior (freezing) has been extensively studied in recent years. We compare phenomenological values of the frozen QCD running coupling between different classes of solutions obtained through non-perturbative Schwinger-Dyson Equations. With these solutions were computed QCD predictions for the asymptotic pion form factor which, in turn, were compared with experiment.

Non-relativistic spacetimes with cosmological constant

Recent data on supernovae favour high values of the cosmological constant. Spacetimes with a cosmological constant have non-relativistic kinematics quite different from Galilean kinematics. de Sitter spacetimes, vacuum solutions of Einstein's equations with a cosmological constant, reduce in the non-relativistic limit to Newton-Hooke spacetimes, which are non-metric homogeneous spacetimes with non-vanishing curvature. The whole non-relativistic kinematics would then be modified, with possible consequences to cosmology, and in particular to the missing-mass problem.

Analysis of the Hb(b)over-bar coupling constant and CP-violation effects at the future e(+)e(-) collider

The e(+)e(-)-->b (B) over bar nu(ν) over bar process, where nu is an electron, muon, or tau-lepton neutrino, is analyzed in detail for the general form of the coupling constant of a Higgs boson with b quarks, with the (m(b)/v)(a + igamma(5)b) parameterization of the Hb (b) over bar interaction. This process is shown to be highly sensitive to this coupling constant. Experiments at the future with roots = 500-GeV linear collider will provide limits of 2 and 20% for deviations of the parameters a and b, respectively, from their Standard Model values. Results concerning the e(+)e(-)-->b (b) over bar nu(ν) over bar process in combination with the independent measurements of the partial width Gamma(H --> b (b) over bar) can testify to the CP origin of the Higgs sector of the theory. (C) 2003 MAIK Nauka/Interperiodica.

Cosmological constant and the speed of light

By exploring the relationship between the propagation of electromagnetic waves in a gravitational field and the light propagation in a refractive medium, it is shown that, in the presence of a positive cosmological constant, the velocity of light will be smaller than its special relativity value. Then, restricting again to the domain of validity of geometrical optics, the same result is obtained in the context of wave optics. It is argued that this phenomenon and the anisotropy in the velocity of light in a gravitational field are produced by the same mechanism.