1,088 research outputs found
Equivalence between the real time Feynman histories and the quantum shutter approaches for the "passage time" in tunneling
We show the equivalence of the functions and
for the ``passage time'' in tunneling. The former, obtained within the
framework of the real time Feynman histories approach to the tunneling time
problem, using the Gell-Mann and Hartle's decoherence functional, and the
latter involving an exact analytical solution to the time-dependent
Schr\"{o}dinger equation for cutoff initial waves
Genetic resources of Spanish hulled wheats
Emmer (Triticum turgidum ssp. dicoccum Schrank em Thell, syn T. dicoccon Schrank) and spelt (T.
aestivum ssp. spelta L. em Thell.) are two hulled wheats that are still grown in some Spanish regions, mainly in
Asturias (North of Spain), where are indistinctly named as escanda. One recent collecting mission carried out in
this Spanish zone has showed the scarce presence of emmer (4 populations), together with the presence of
foreigner spelt that could change the genetic patrimony of the escanda, because of present agronomic
characteristics more adapted to the present requirements than the autochthon spelt lines. This supposes one
clear danger to the maintaining of these hulled wheats, together with the lost of diversity associated to them. The
endosperm storage proteins have showed to be good markers for measure of this diversity. The analysis of the
autochthon populations collected showed wide variation for the storage proteins, also as for morphological traits.
In conclusion, we think that the evaluation of these genetic resources could be useful for enlarging the
background of the modern wheats. Likewise, for the obtaining of escanda lines with better agronomical,
morphological and quality traits than the actual lines, with the advantage of to be materials adapted to the special
conditions of the cultivated zon
Variation of High Molecular Weight Glutenin Subunits in Two Neglected Tetraploid Wheat Subspecies
The genetic diversity of 140 accessions of Triticum turgidum ssp. carthlicum Nevski em. A. Löve &
D. Löve and 159 accessions of T. turgidum ssp. polonicum L. em. Thell. was evaluated by the analysis of HMW
glutenin subunits. Seven allelic variants were found among the carthlicum accessions: three at the Glu-A1 locus
(two of them were novel alleles) and four at the Glu-B1 locus (one of them novel). More variability was found
among the polonicum accessions with 16 allelic variants: six at the Glu-A1 locus (three of them novel), and ten
at the Glu-B1 locus (five of them novel). Totally, ten new alleles were found, one of which appeared in both
subspecies. Out of 19 different combinations of alleles detected in both subspecies, 14 were novel. Based on the
available passport data, the carthlicum accessions could be separated by origin into 18 groups, and the polonicum
accessions into 33 such groups. The genetic diversity was lower among the carthlicum (Ht = 0.174) than among
the polonicum accessions (Ht = 0.562). In both subspecies, most diversity was present between groups differing
in origin, whereas diversity within the groups was very low. The detected variability offers possibilities for the
improvement of bread making quality in durum wheat through introduction of newly detected alleles and for
the broadening of genetic diversity in this wheat species
Physical Properties and Chemical Characterization of Macro- and Micro-Nutriments of Elite Blue Maize Hybrids (Zea mays L.)
Five elite blue maize hybrids and two blue maize landraces were evaluated for various quality characteristics. Hybrids showed physical characteristics demanded by dry-millers and tortilla processors: above 290 g in one hundred-kernel weight test, higher test weight (76.1–78.5 kg hl−1) and lower flotation index (22–61%). Hybrid maize 613 × 27 (9.9%) and 611 × 8 (9.5%) contained the highest protein. Potassium, magnesium, manganese and zinc contents of hybrid maize were higher than landraces by 15, 30, 55 and 41%, respectively. Nutrimental profile showed linoleic acid contents above 50% in 503 × 67, 613 × 27 and 611 × 8 hybrid samples. Lysine levels of landraces and hybrids 503 × 67 (33.9 g kg−1 protein) and 631 × 27 (31.7 g kg−1 protein) were higher than reported for regular white corn (27 g kg−1 protein), as well as the highest tryptophan levels for Chalqueno (6.0 g kg−1 protein) and hybrid 503 × 67 (6.9 g kg−1 protein). Highest protein quality based on its digestibility was found in hybrid 503 × 67. Results indicated that elite blue maize hybrids could be an important source of nutrimental compounds with potential for functional food industries
Cambios en la representación polínica de los ecosistemas fluvio-marinos de transición del entorno de la Ría de Vigo durante los últimos 1500 años
XV lnternational A.P.L.E. Symposium of Palynolog
Slowly rotating charged fluid balls and their matching to an exterior domain
The slow-rotation approximation of Hartle is developed to a setting where a
charged rotating fluid is present. The linearized Einstein-Maxwell equations
are solved on the background of the Reissner-Nordstrom space-time in the
exterior electrovacuum region. The theory is put to action for the charged
generalization of the Wahlquist solution found by Garcia. The Garcia solution
is transformed to coordinates suitable for the matching and expanded in powers
of the angular velocity. The two domains are then matched along the zero
pressure surface using the Darmois-Israel procedure. We prove a theorem to the
effect that the exterior region is asymptotically flat if and only if the
parameter C_{2}, characterizing the magnitude of an external magnetic field,
vanishes. We obtain the form of the constant C_{2} for the Garcia solution. We
conjecture that the Garcia metric cannot be matched to an asymptotically flat
exterior electrovacuum region even to first order in the angular velocity. This
conjecture is supported by a high precision numerical analysis.Comment: 11 pages, 2 figure
Electron energy loss and induced photon emission in photonic crystals
The interaction of a fast electron with a photonic crystal is investigated by
solving the Maxwell equations exactly for the external field provided by the
electron in the presence of the crystal. The energy loss is obtained from the
retarding force exerted on the electron by the induced electric field. The
features of the energy loss spectra are shown to be related to the photonic
band structure of the crystal. Two different regimes are discussed: for small
lattice constants relative to the wavelength of the associated electron
excitations , an effective medium theory can be used to describe the
material; however, for the photonic band structure plays an
important role. Special attention is paid to the frequency gap regions in the
latter case.Comment: 12 pages, 7 figure
Multivariate analysis of the dominant and sub-dominant epipelic diatoms and water quality data from South African rivers
Data are presented on the distribution of the dominant and sub-dominant epipelic diatoms found in South African rivers from different regions of the country. A multivariate analysis identified 36 diatom species that were associated with different levels of TDS, PO4, NH4 and SiO2. Three groups of rivers were identified. Group I consisted of sites with high PO4 and SiO2, which corresponded to Durban Metropolitan Area sites, Kruger National Park rivers, the rivers in the Johannesburg Metropolitan Area and the Orange River. In these rivers 12 diatom species were identified that might indicate those water quality characteristics. Group II included stations where the water quality had high TDS and NH4 values which were associated with most stations in the Swartkops River in the Eastern Cape. The indicators in this group comprised 12 diatom species. Group III were from sampling stations where the water had low levels of minerals, i.e. the upper reaches of the Gamtoos River and the Swartkops River in the Eastern Cape, the Olifants River in the Northern Cape, rivers sampled in KwaZulu-Natal and the Northern Cape. At these sites, 13 diatom species were found as dominants in this better water quality. Water quality data collected during this study showed that over 50% of the river systems display some degree of eutrophication and thus efforts should be made to reduce inputs of nutrients and pollutants to those rivers.Keywords: ammonium, diatoms, phosphate, rivers, South Africa, total dissolved solid
Methods and Tools for Objective Assessment of Psychomotor Skills in Laparoscopic Surgery
Training and assessment paradigms for laparoscopic surgical skills are evolving from traditional mentor–trainee tutorship towards structured, more objective and safer programs. Accreditation of surgeons requires reaching a consensus on metrics and tasks used to assess surgeons’ psychomotor skills. Ongoing development of tracking systems and software solutions has allowed for the expansion of novel training and assessment means in laparoscopy. The current challenge is to adapt and include these systems within training programs, and to exploit their possibilities for evaluation purposes. This paper describes the state of the art in research on measuring and assessing psychomotor laparoscopic skills. It gives an overview on tracking systems as well as on metrics and advanced statistical and machine learning techniques employed for evaluation purposes. The later ones have a potential to be used as an aid in deciding on the surgical competence level, which is an important aspect when accreditation of the surgeons in particular, and patient safety in general, are considered. The prospective of these methods and tools make them complementary means for surgical assessment of motor skills, especially in the early stages of training. Successful examples such as the Fundamentals of Laparoscopic Surgery should help drive a paradigm change to structured curricula based on objective parameters. These may improve the accreditation of new surgeons, as well as optimize their already overloaded training schedules
Generalized plane-fronted gravitational waves in any dimension
We study the gravitational waves in spacetimes of arbitrary dimension. They
generalize the pp-waves and the Kundt waves, obtained earlier in four
dimensions. Explicit solutions of the Einstein and Einstein-Maxwell equations
are derived for an arbitrary cosmological constant.Comment: Revtex, 18 pages, no figure
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