Use of sweeteners in osmotic pretreatment before freeze-drying of pear and pineapple

The aim of the study was to analyse the influence of the type of osmotic substance (sucrose, glucose, xylitol, trehalose, and sorbitol) on the physicochemical properties of freeze-dried fruit (pear and pineapple). Controlling the functional properties of freeze-dried fruit after osmotic dehydration with aqueous solutions at water activity of a w=0.90 is presented. Decrease in the water adsorption index (WAI) was recorded for all dehydrated samples. The largest decrease (for pears and pineapples by 25 and 65%, respectively) was observed in osmoactive solutions containing trehalose. Considerable increase in the FAI was recorded in samples of dehydrated pineapple. In osmoactive trehalose solutions that increase hardly reached 46%, whereas in sorbitol and xylitol its value elevated to 39% and 13%, respectively. Regardless of the osmoactive sweetener applied prior to freeze-drying, an increase in specific surface area (SBET) of dried materials was observed. For dehydrated pears, SBET ranged from 96 to 697 m2 g−1, and for pineapple, from 115 to 938 m2 g−1. Osmotic dehydration before lyophilisation of fruit samples weakened rehydration relative to the control. The dehydration carried out with osmoactive sweeteners, that is, sorbitol, xylitol, and trehalose, allows obtaining a product with good functional properties that can be successfully used for supplementation of dietary products, in particular for diabetics

Decay Modes of Unstable Strings in Plane-Wave String Field Theory

The cubic interaction vertex of light-cone string field theory in the plane-wave background has a simple effective form when considering states with only bosonic excitations. This simple effective interaction vertex is used in this paper to calculate the three string interaction matrix elements for states of arbitrary bosonic excitation and these results are used to examine certain decay modes on the mass-shell. It is shown that the matrix elements of one string to two string decays involving only bosonic excitations will vanish to all orders in 1/mu on the mass-shell when the number of excitations on the initial string is less than or equal to two, but in general will not vanish when the number of excitations is greater than two. Also, a truncated calculation of the mass-shell matrix elements for one string to three string decays of two excitation states is performed and suggests that these matrix elements do not vanish on the mass-shell. There is, however, a quantitative discrepancy between this last result and its (also non-vanishing) gauge theory prediction from the BMN correspondence.Comment: 11 pages; v2: references added; v3: normalization of interaction vertex and corresponding amplitudes changed by a factor of mu to reflect SFT normalization (must now divide by mu to compare with BMN dual gauge theory), and minor errors correcte

Chiral primary cubic interactions from pp-wave supergravity

We explicitly construct cubic interaction light-cone Hamiltonian for the chiral primary system involving the metric fields and the self-dual four-form fields in the IIB pp-wave supergravity. The background fields representing pp-waves exhibit SO(4)*SO(4)*Z_2 invariance. It turns out that the interaction Hamiltonian is precisely the same as that for the dilaton-axion system, except for the fact that the chiral primary system fields have the opposite parity to that of the dilaton-axion fields under the Z_2 transformation that exchanges two SO(4)'s.Comment: 14 pages, A few comments are adde

Conformal Dimensions of Two-Derivative BMN Operators

We compute the anomalous dimensions of BMN operators with two covariant derivative impurities at the planar level up to first order in the effective coupling lambda'. The result equals those for two scalar impurities as well as for mixed scalar and vector impurities given in the literature. Though the results are the same, the computation is very different from the scalar case. This is basically due to the existence of a non-vanishing overlap between the derivative impurity and the ``background'' field Z. We present details of these differences and their consequences.Comment: 27 pages, v2: references added, minor change

An alternative formulation of light-cone string field theory on the plane wave

We construct a manifestly SO(4) x SO(4) invariant, supersymmetric extension of the closed string cubic interaction vertex and dynamical supercharges in light-cone string field theory on the plane wave space-time. We find that the effective vertex for states built out of bosonic creation oscillators coincides with the one previously constructed in the SO(8) formalism and conjecture that in general the two formulations are physically equivalent. Further evidence for this claim is obtained from the discrete Z_2-symmetry of the plane wave and by computing the mass-shift of the simplest stringy state using perturbation theory. We verify that the leading non-planar correction to the anomalous dimension of the dual gauge theory operators is correctly recovered.Comment: 28 pages; v2: minor change

String interactions and discrete symmetries of the pp-wave background

Free string theory on the plane-wave background displays a discrete Z2 symmetry exchanging the two transverse SO(4) rotation groups. This symmetry should be respected also at the interacting level. We show that the zero mode structure proposed in hep-th/0208148 can be completed to a full kinematical vertex, contrary to claims appeared in the previous literature. We also comment on the relation with recent works on the string-bit formalism and on the comparison with the field theory side of the correspondence.Comment: Proceeding of the 35th Symposium Ahrenshoop Aug 2002 and the Leuven RTN-workshop Sept 200

The 3-string vertex and the AdS/CFT duality in the PP-wave limit

We pursue the study of string interactions in the PP-wave background and show that the proposal of hep-th/0211188 can be extended to a full supersymmetric vertex. Then we compute some string amplitudes in both the bosonic and fermionic sector, finding agreement with the field theory results at leading order in lambda'.Comment: Latex, 25 pages. Comments added and typos correcte

Tracing the String: BMN correspondence at Finite J^2/N

Employing the string bit formalism of hep-th/0209215, we identify the basis transformation that relates BMN operators in N=4 gauge theory to string states in the dual string field theory at finite g_2=J^2/N. In this basis, the supercharge truncates at linear order in g_2, and the mixing amplitude between 1 and 2-string states precisely matches with the (corrected) answer of hep-th/0206073 for the 3-string amplitude in light-cone string field theory. Supersymmetry then predicts the order g_2^2 contact term in the string bit Hamiltonian. The resulting leading order mass renormalization of string states agrees with the recently computed shift in conformal dimension of BMN operators in the gauge theory.Comment: 11 pages, 1 figur

D-branes in PP-wave light cone string field theory

The cubic interaction vertex and the dynamical supercharges are constructed for open strings ending on D7-branes, in light-cone superstring field theory in PP-wave background. In this context, we write down the symmetry generators in terms of the relevant group structure: SU(2) x SU(2) x SO(2) x SO(2), originating from the eight transverse directions in the PP-wave background and use the expressions to explicitly construct the vertex at the level of stringy zero modes. The results are further generalized to include all the stringy excitations as well.Comment: 30 pages, correction in eqn. (4.28), few equations (appendix), Comments (p.17-18) and a reference (no. 58) added, typo is corrected in eqn. (4.5

Stringing Spins and Spinning Strings

We apply recently developed integrable spin chain and dilatation operator techniques in order to compute the planar one-loop anomalous dimensions for certain operators containing a large number of scalar fields in N =4 Super Yang-Mills. The first set of operators, belonging to the SO(6) representations [J,L-2J,J], interpolate smoothly between the BMN case of two impurities (J=2) and the extreme case where the number of impurities equals half the total number of fields (J=L/2). The result for this particular [J,0,J] operator is smaller than the anomalous dimension derived by Frolov and Tseytlin [hep-th/0304255] for a semiclassical string configuration which is the dual of a gauge invariant operator in the same representation. We then identify a second set of operators which also belong to [J,L-2J,J] representations, but which do not have a BMN limit. In this case the anomalous dimension of the [J,0,J] operator does match the Frolov-Tseytlin prediction. We also show that the fluctuation spectra for this [J,0,J] operator is consistent with the string prediction.Comment: 27 pages, 4 figures, LaTex; v2 reference added, typos fixe