467 research outputs found
Classical approach in quantum physics
The application of a classical approach to various quantum problems - the
secular perturbation approach to quantization of a hydrogen atom in external
fields and a helium atom, the adiabatic switching method for calculation of a
semiclassical spectrum of hydrogen atom in crossed electric and magnetic
fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's
approach to Stark problem, long-lived excited states of a helium atom recently
discovered with the help of Poincar section, inelastic
transitions in slow and fast electron-atom and ion-atom collisions - is
reviewed. Further, a classical representation in quantum theory is discussed.
In this representation the quantum states are treating as an ensemble of
classical states. This approach opens the way to an accurate description of the
initial and final states in classical trajectory Monte Carlo (CTMC) method and
a purely classical explanation of tunneling phenomenon. The general aspects of
the structure of the semiclassical series such as renormgroup symmetry,
criterion of accuracy and so on are reviewed as well. In conclusion, the
relation between quantum theory, classical physics and measurement is
discussed.Comment: This review paper was rejected from J.Phys.A with referee's comment
"The author has made many worthwhile contributions to semiclassical physics,
but this article does not meet the standard for a topical review"
Higher dimensional supersymmetry in 4D superspace
We present an explicit formulation of supersymmetric Yang-Mills theories from
\D= 5 to 10 dimensions in the familiar \N=1,\D=4 superspace. This provides
the rules for globally supersymmetric model building with extra dimensions and
in particular allows us to simply write down SUSY preserving
interactions between bulk fields and fields localized on branes. We present a
few applications of the formalism by way of illustration, including
supersymmetric ``shining'' of bulk fields, orbifolds and localization of chiral
fermions, anomaly inflow and super-Chern-Simons theories.Comment: Typos corrected. Added reference to early work by Marcus, Sagnotti
and Siegel and a term to the non-Abelian Lagrangian for D>5 formally needed
for gauge invariance. The results however remain unchange
Bioactive composition and free radical scavenging activity of fresh orange maize hybrids: impacts of genotype, maturity stages, and processing methods
Open Access Journal; Published online: 24 Feb 2021Bioactive compounds in foods are responsible for their biological activities, but biotic and abiotic factors may influence their levels. This study evaluated the impact of three genotypes (designated 4, 5, and 7), maturity stages (20, 27, and 34 days after pollination) and processing methods (hydrothermal and dry-heating) on the bioactive constituents (carotenoids, phytate, tannins, vitamin C) and 2,2-diphenyl-2-picrylhydrazyl radical (DPPH*) scavenging activity of fresh orange maize hybrids. Freshly harvested maize cobs of each genotype were subjected to hydrothermal processing at 100°C and dry-heating with husks and without husks. Carotenoids (lutein, zeaxanthin, ÎČ-cryptoxanthin, α-carotene, and total ÎČ-carotene) contents of fresh and processed samples were analyzed using HPLC; other bioactive constituents and DPPH* scavenging ability were determined using spectrophotometric methods. Genotype had a significant effect on the levels of carotenoids (p < 0.001) and vitamin C (p < 0.05), while genotype (p < 0.001), and processing methods (p < 0.001) had significant effects on DPPH* SC50. Maturity stages, processing methods and their interaction also had significant effects (p < 0.001) on the levels of all the bioactive constituents. A positive moderate to strong correlation was observed between (p < 0.001) α-carotene and the following: lutein (r = 0.57), ÎČ-cryptoxanthin (r = 0.69), total ÎČ-carotene (r = 0.62). However, the relationship between α-carotene and zeaxanthin was positive but weak (r = 0.39). A positive moderate correlation (p < 0.001) was observed between lutein and the following: ÎČ-cryptoxanthin (r = 0.57), total ÎČ-carotene (r = 0.58), and zeaxanthin (r = 0.52). A positive strong correlation (p < 0.001) was observed between ÎČ-cryptoxanthin and each of total ÎČ-carotene (r = 0.92) and zeaxanthin (r = 0.63); total ÎČ-carotene and zeaxanthin (r = 0.65); while the association between vitamin C and DPPH* SC50 was negative and weak (r = â0.38). Generally, genotype 4 and harvesting at 34 days after pollination had the best combination of bioactive constituents and DPPH* scavenging ability
Characterization of striga-resistant yellow-orange maize hybrids for bioactive, carbohydrate and pasting properties
Open Access Journal; Published online: 10 Dec 2020Understanding the bioactive constituents and physicochemical components in cereals can provide insights into their potential health benefits and food applications. This study evaluated some bioactive constituents, carbohydrate profiles and pasting properties of 16 Striga-resistant hybrids, with yellow-orange kernel color and semi-flint to flint kernel texture, grown in two replications at two field locations in Nigeria. Carotenoids were quantified using HPLC, while other analyses were carried out using standard laboratory methods. The ranges of major carotenoids (”g/g) across the two locations varied from 2.6 to 9.6 for lutein, from 2.1 to 9.7 for zeaxanthin, from 0.8 to 2.9 for ÎČ-cryptoxanthin, from 1.4 to 4.1 for ÎČ-carotene; with total xanthophylls and provitamin A carotenoids (pVAC) ranging from 5.4 to 17.1 and 1.4 to 4.1”g/g, respectively. Tannins content ranged from 2.1 to 7.3 mg/g, while phytate ranged from 0.4 to 7.1%. Starch, free sugar, amylose and amylopectin ranged from 40.1 to 88.9%, 1.09 to 6.5%, 15.0 to 34.1%, and 65.9
to 85.0%, respectively. Peak and final viscosities ranged from 57.8 to 114.9 and 120.3 to 261.6 Rapid Visco Units (RVU), respectively. Total xanthophylls, ÎČ-carotene, tannins, phytate, sugar, amylose and amylopectin levels, as well as peak and final viscosities, varied significantly (p < 0.05) across the hybrids. Amylose was significantly correlated (p< 0.05) with total xanthophylls, ÎČ-carotene, pVAC, phytate and pasting temperature (r = 0.3, 0.3, 0.4, 0.3, 0.3, respectively), but starch significantly correlated with tannins (r = 0.3). Hence, the Striga-resistant yellow-orange maize hybrids have a good combination of bioactive constituents, carbohydrate profile and pasting properties, which are partly influenced by hybrid
Antioxidant, starch-digesting enzymes inhibitory, and pasting properties of elite yellow-fleshed cassava genotypes
Open Access Journal; Published online: 16 Mar 2023Biofortification of cassava roots has improved its health benefits by raising the quantity and bioavailability of bioactive compounds, particularly carotenoids. This study analyzed the bioactive constituents (carotenoids, tannins, total phenolics, and flavonoids), antioxidant, starch-digesting enzymes (a-amylase and a-glucosidase) inhibitory and pasting properties of flours of 18 elite yellow-fleshed cassava genotypes grown at the International Institute of Tropical Agriculture, Ibadan, using standard laboratory methods. Generally, the concentrations of the bioactive constituents (9-cis- -carotene, 13-cis- -carotene, all trans- -carotene, total -carotene, total carotenoids, tannins, total phenolics, and total flavonoids) of the dierent cassava genotypes varied. The antioxidant activity varied significantly among the dierent cassava genotypes, with IITA-TMS-IBA183001 having the highest reducing power (2.59 GAE mg/g) and most potent DPPH· scavenging ability (SC50: 14.56 mg/mL). However, the starch-hydrolysing enzymes (alpha-amylase and alpha-glucosidase) inhibitory and the pasting properties of the dierent genotypes were generally comparable. Total carotenoids content significantly correlated with the DPPH· SC50 (r = â0.495), while total phenolics content correlated with ABTS·+(r = 0.839) and DPPH· SC50 (r = â0.870). Also, tannins content significantly correlated with ABTS·+ (r = 0.553), while total flavonoids content was significantly correlated with a-amylase IC50 (r = â0.532). These findings suggest the potential of flours of the 18 elite yellow-fleshed cassava genotypes to serve as important dietary sources of antioxidants and starch-hydrolysing enzyme inhibitors, which may be beneficial in oxidative stress and postprandial hyperglycaemic conditions
Anomalies, Fayet-Iliopoulos terms and the consistency of orbifold field theories
We study the consistency of orbifold field theories and clarify to what
extent the condition of having an anomaly-free spectrum of zero-modes is
sufficient to guarantee it. Preservation of gauge invariance at the quantum
level is possible, although at the price, in general, of introducing operators
that break the 5d local parity. These operators are, however, perfectly
consistent with the orbifold projection. We also clarify the relation between
localized Fayet-Iliopoulos (FI) terms and anomalies. These terms can be
consistently added, breaking neither local supersymmetry nor the gauge
symmetry. In the framework of supergravity the localized FI term arises as the
boundary completion of a bulk interaction term: given the bulk Lagrangian the
FI is fixed by gauge invariance.Comment: 31 pages, 1 figure. v2: some typos corrected, references adde
Localized anomalies in orbifold gauge theories
We apply the path-integral formalism to compute the anomalies in general
orbifold gauge theories (including possible non-trivial Scherk-Schwarz boundary
conditions) where a gauge group G is broken down to subgroups H_f at the fixed
points y=y_f. Bulk and localized anomalies, proportional to \delta(y-y_f), do
generically appear from matter propagating in the bulk. The anomaly zero-mode
that survives in the four-dimensional effective theory should be canceled by
localized fermions (except possibly for mixed U(1) anomalies). We examine in
detail the possibility of canceling localized anomalies by the Green-Schwarz
mechanism involving two- and four-forms in the bulk. The four-form can only
cancel anomalies which do not survive in the 4D effective theory: they are
called globally vanishing anomalies. The two-form may cancel a specific class
of mixed U(1) anomalies. Only if these anomalies are present in the 4D theory
this mechanism spontaneously breaks the U(1) symmetry. The examples of five and
six-dimensional Z_N orbifolds are considered in great detail. In five
dimensions the Green-Schwarz four-form has no physical degrees of freedom and
is equivalent to canceling anomalies by a Chern-Simons term. In all other
cases, the Green-Schwarz forms have some physical degrees of freedom and leave
some non-renormalizable interactions in the low energy effective theory. In
general, localized anomaly cancellation imposes strong constraints on model
building.Comment: 30 pages, 4 figures. v2: reference adde
Two-Loop Helicity Amplitudes for Quark-Gluon Scattering in QCD and Gluino-Gluon Scattering in Supersymmetric Yang-Mills Theory
We present the two-loop QCD helicity amplitudes for quark-gluon scattering,
and for quark-antiquark annihilation into two gluons. These amplitudes are
relevant for next-to-next-to-leading order corrections to (polarized) jet
production at hadron colliders. We give the results in the `t Hooft-Veltman and
four-dimensional helicity (FDH) variants of dimensional regularization. The
transition rules for converting the amplitudes between the different variants
are much more intricate than for the previously discussed case of gluon-gluon
scattering. Summing our two-loop expressions over helicities and colors, and
converting to conventional dimensional regularization, gives results in
complete agreement with those of Anastasiou, Glover, Oleari and Tejeda-Yeomans.
We describe the amplitudes for 2 to 2 scattering in pure N=1 supersymmetric
Yang-Mills theory, obtained from the QCD amplitudes by modifying the color
representation and multiplicities, and verify supersymmetry Ward identities in
the FDH scheme.Comment: 77 pages. v2: corrected errors in eqs. (3.7) and (3.8) for one-loop
assembly; remaining results unaffecte
Influence of traditional processing and genotypes on the antioxidant and antihyperglycaemic activities of yellow-fleshed cassava
Open Access Journal; Published online: 14 Oct 2022Yellow-fleshed cassava root (YFCR) is processed into traditional products that may influence its bioactivities. In this study, the antioxidant and anti-hyperglycaemic activities of three traditional products (lafun, fufu and gari) from five genotypes (IITA-TMS-IBA070337, 182961, 182962, 182986, 183044) of YFCR were evaluated. The YFCR genotypes were grown at the International Institute of Tropical Agriculture (IITA) research field, Ibadan. The bioactive constituents (total carotenoids, total phenolics, tannins and total flavonoids), antioxidant [2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) radical cation (ABTSâą+) and 1,1-diphenyl-2- picrylhydrazyl radical (DPPHâą) scavenging capacities, and reducing power], and starch-digesting enzymes (a-amylase and a-glucosidase) inhibitory activities of the products
were determined using standard laboratory methods. The glucose response of the products was assessed in human subjects. The concentrations of the bioactive constituents of the products from different genotypes varied significantly (p < 0.05). The ABTSâą+ and DPPHâą scavenging capacities and the reducing power of the products also differed significantly (p < 0.05), such that the lafun from IITA-TMS-IBA182962, IITA-TMS-IBA070337 and IITA-TMS-IBA070337 had the strongest ABTSâą+ and DPPHâą scavenging
capacities, and reducing power, respectively. The a-amylase and a-glucosidase inhibitory activities of the three products differed significantly (p < 0.05), with the lafun from IITA-TMS-IBA070337 and IITA-TMS-IBA07033 having the strongest a-amylase and a-glucosidase inhibitory activity, respectively. Also,
the lafun from IITA-TMS-182986 had the least glucose response, while the fufu from IITA-TMS-IBA070337 had the highest glucose response. Overall, the lafun from different genotypes of YFCR had the most potent antioxidant and starch-digesting enzymes inhibitory activities and the least glucose responses. Hence, lafun may be a promising dietary intervention targeting oxidative stress, hyperglycaemia, and their resultant type 2 diabetes
Indirect search for dark matter: prospects for GLAST
Possible indirect detection of neutralino, through its gamma-ray annihilation
product, by the forthcoming GLAST satellite from our galactic halo, M31, M87
and the dwarf galaxies Draco and Sagittarius is studied. Gamma-ray fluxes are
evaluated for the two representative energy thresholds, 0.1 GeV and 1.0 GeV, at
which the spatial resolution of GLAST varies considerably. Apart from dwarfs
which are described either by a modified Plummer profile or by a
tidally-truncated King profiles, fluxes are compared for halos with central
cusps and cores. It is demonstrated that substructures, irrespective of their
profiles, enhance the gamma-ray emission only marginally. The expected
gamma-ray intensity above 1 GeV at high galactic latitudes is consistent with
the residual emission derived from EGRET data if the density profile has a
central core and the neutralino mass is less than 50 GeV, whereas for a central
cusp only a substantial enhancement would explain the observations. From M31,
the flux can be detected above 0.1 GeV and 1.0 GeV by GLAST only if the
neutralino mass is below 300 GeV and if the density profile has a central cusp,
case in which a significant boost in the gamma-ray emission is produced by the
central black hole. For Sagittarius, the flux above 0.1 GeV is detectable by
GLAST provided the neutralino mass is below 50 GeV. From M87 and Draco the
fluxes are always below the sensitivity limit of GLAST.Comment: 14 Pages, 7 Figures, 3 Tables, version to appear on Physical Review
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