8,073 research outputs found
Comparative study of total phenolic content and radical scavenging activity of conventionally and organically grown herbs
The aim of the present study was to measure the relative phenolic content in commonly available conventionally and organically grown herbs and to evaluate their antioxidant capacity. Sage (Salvia officinalis), lemon balm (Melissa officinalis) and peppermint (Mentha x piperita) leaves, corriander (Corriandrum sativum) and fennel (Foeniculum vulgare) seeds were used in the present investigation.
Total phenolic content (TPhC), measured by Folin-Ciocalteu method, and radical scavenging activity (RSA), using DPPH method were determined in infusions prepared from above mentioned herbs. TPhC ranged from 75.9 to 1126.5 gallic acid equivalents (GAE) mg/l infusion and RSA – from 7.03 to 91.65%. The obtained data also showed that infusions prepared from organically grown sage, peppermint and lemon balm were slightly higher than those obtained from conventionally grown herbs
Time dependent correlations in marine stratocumulus cloud base height records
The scaling ranges of time correlations in the cloud base height records of
marine boundary layer stratocumulus are studied applying the Detrended
Fluctuation Analysis statistical method. We have found that time dependent
variations in the evolution of the exponent reflect the diurnal
dynamics of cloud base height fluctuations in the marine boundary layer. In
general, a more stable structure of the boundary layer corresponds to a lower
value of the - indicator, i.e. larger anti-persistence, thus a set of
fluctuations tending to induce a greater stability of the stratocumulus. In
contrast, during periods of higher instability in the marine boundary, less
anti-persistent (more persistent like) behavior of the system drags it out of
equilibrium, corresponding to larger values. From an analysis of the
frequency spectrum, the stratocumulus base height evolution is found to be a
non-stationary process with stationary increments. The occurrence of these
statistics in cloud base height fluctuations suggests the usefulness of similar
studies for the radiation transfer dynamics modeling.Comment: 12 pages, 6 figures; to appear in Int. J. Mod. Phys. C, Vol. 13, No.
2 (2002
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Origin of the ungrouped achondrite NWA 4518: mineralogy and geochemistry of FeNi-metal
Ungrouped achondrite NWA 4518 is an ultramafic breccia with abundant siderophile rich IIA-like metal. Its silicate chemistry is similar to that of WINs, HEDs, and silicate inclusions of IIE irons. Oxygen isotopic composition is nearby IAB-IIICD-WIN
On the D-wave state component of the deuteron in the Nambu-Jona-Lasinio model of light nuclei
The D-wave state component of the neutron-proton bound state in the deuteron
is calculated in the Nambu-Jona-Lasinio model of light nuclei - the
relativistically covariant quantum field theoretic approach to the description
of low-energy nuclear forces. The theoretical value of the fraction of the
D-wave state relative to the S-wave state is equal to eta_d = 0.0238. This
agrees well with the phenomenological value eta_d = 0.0256(4) quoted by
Kamionkowski and Bahcall (ApJ. 420, 884 (1994)).Comment: 7 pages, latex, no figure
Six-loop expansion study of three-dimensional -vector model with cubic anisotropy
The six-loop expansions of the renormalization-group functions of
-vector model with cubic anisotropy are calculated within the minimal
subtraction (MS) scheme in dimensions. The
expansions for the cubic fixed point coordinates, critical exponents
corresponding to the cubic universality class and marginal order parameter
dimensionality separating different regimes of critical behavior are
presented. Since the expansions are divergent numerical estimates
of the quantities of interest are obtained employing proper resummation
techniques. The numbers found are compared with their counterparts obtained
earlier within various field-theoretical approaches and by lattice
calculations. In particular, our analysis of strengthens the existing
arguments in favor of stability of the cubic fixed point in the physical case
A combinatorial approach to the set-theoretic solutions of the Yang-Baxter equation
A bijective map , where
is a finite set, is called a \emph{set-theoretic solution of the Yang-Baxter
equation} (YBE) if the braid relation
holds in A non-degenerate involutive solution satisfying
, for all , is called \emph{square-free solution}. There
exist close relations between the square-free set-theoretic solutions of YBE,
the semigroups of I-type, the semigroups of skew polynomial type, and the
Bieberbach groups, as it was first shown in a joint paper with Michel Van den
Bergh.
In this paper we continue the study of square-free solutions and the
associated Yang-Baxter algebraic structures -- the semigroup , the
group and the - algebra over a field , generated by
and with quadratic defining relations naturally arising and uniquely
determined by . We study the properties of the associated Yang-Baxter
structures and prove a conjecture of the present author that the three notions:
a square-free solution of (set-theoretic) YBE, a semigroup of I type, and a
semigroup of skew-polynomial type, are equivalent. This implies that the
Yang-Baxter algebra is Poincar\'{e}-Birkhoff-Witt type algebra,
with respect to some appropriate ordering of . We conjecture that every
square-free solution of YBE is retractable, in the sense of Etingof-Schedler.Comment: 34 page
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