188 research outputs found
Effect of gamma radiation of 60Co on sunflower plants (Helianthus annuus L.) (Asteraceae), from irradiated achenes
In order to know the effect of 60Co gamma irradiation, in the sunflower crop, were irradiated achenes in the Transelektro LGI-01 in the Instituto Nacional de Investigaciones Nucleares. The data was evaluated under a completely randomized design, where the treatments were 0, 100, 200, 300, 400, 500, 600, 700, 800 and 900 Gy and four repetitions (10x4) = 40 experimental units. The response variables were: plant height, root length and volume, dry biomass. The results indicated that germination and sprouting decreased as the radiation increased, adjusting these to a quadratic model. Plant height, length, root volume and dry biomass decreased at high doses. From this investigation it was concluded, that doses of 100 and 200 Gy, have a stimulating effect on plant height and root length, being an important agent, to induce genetic variability in sunflower
Servicio de Control Microbiológico (SCM), como Estrategia Didáctica para el laboratorio de Tecnología de Alimentos [Microbiological Control Service, as Didactic Strategy for Food Technology Lab]
Servicio de Control Microbiológico (SCM) es una Estrategia Didáctica dirigida a alumnos de Laboratorios de: Tecnología de Alimentos (LABTEC) y Microbiología de Alimentos (LMA), en la Facultad de Química (FQ) de la Universidad Nacional Autónoma de México (UNAM). Se basa en el desempeño de roles profesionales, donde alumnos de LABTEC que elaboran alimentos actúan como productores que requieren análisis microbiológicos; los alumnos de LMA actúan como proveedores del servicio de control microbiológico. Se elaboran solicitudes y reportes formales, basados en normas de referencia, para que se pueda concluir sobre la calidad higiénica del alimento. La estrategia ha permitido a los participantes, una experiencia muy cercana al ejercicio profesional, para evaluar buenas prácticas de manufactura, trabajo individual y en equipo. Todos desarrollaron habilidades de comunicación profesional, solución de problemas y conciencia sobre la importancia de la calidad higiénica de los alimentos. El control microbiológico en LABTEC se ha realizado sin recursos adicionales, pues se aplican aquellos destinados a las prácticas de LMA. Además de la experiencia de aprendizaje, se está generando mejora continua en ambas asignaturas.
[Microbiological control service (SCM) as a didactic strategy is aimed to those students in laboratories of food technology (LABTEC) and food microbiology (LMA), at the Universidad Nacional Autónoma de México’s School of Chemistry (FQ). It is based in professional role playing; LABTEC students elaborate the products and act as food producers in need of microbiological analysis; LMA students perform as service providers, for microbiological control. They elaborate formal requests and microbiological analysis report, based on mandatory standards, which can lead to conclusions about product’s hygienic quality. The strategy has given students an experience close to professional practice, to evaluate good manufacturing practices, individual and team work. All developed professional communication skills, problems identification and proposals for solving them, as well as consciousness about the importance of hygienic quality of food. The microbiological control in LABTEC has been carried out without the need for additional resources, since those intended for LMA practices are applied to these real samples. The experience is generating continuous improvement in both courses.
Tissue culture of ornamental cacti
Cacti species are plants that are well adapted to growing in arid and semiarid regions where the main problem is water availability. Cacti have developed a series of adaptations to cope with water scarcity, such as reduced leaf surface via morphological modifications including spines, cereous cuticles, extended root systems and stem tissue modifications to increase water storage, and crassulacean acid metabolism to reduce transpiration and water loss. Furthermore, seeds of these plants very often exhibit dormancy, a phenomenon that helps to prevent germination when the availability of water is reduced. In general, cactus species exhibit a low growth rate that makes their rapid propagation difficult. Cacti are much appreciated as ornamental plants due to their great variety and diversity of forms and their beautiful short-life flowers; however, due to difficulties in propagating them rapidly to meet market demand, they are very often over-collected in their natural habitats, which leads to numerous species being threatened, endangered or becoming extinct. Therefore, plant tissue culture techniques may facilitate their propagation over a shorter time period than conventional techniques used for commercial purposes; or may help to recover populations of endangered or threatened species for their re-introduction in the wild; or may also be of value to the preservation and conservation of the genetic resources of this important family. Herein we present the state-of-the-art of tissue culture techniques used for ornamental cacti and selected suggestions for solving a number of the problems faced by members of the Cactaceae family
Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV
We present a search for the production of neutral Higgs bosons decaying into
tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The
data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by
the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the
95% C.L. on the product of production cross section and branching ratio for a
scalar resonance decaying into tautau pairs, and we then interpret these limits
as limits on the production of Higgs bosons in the minimal supersymmetric
standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL
Measurement of the photon-jet production differential cross section in collisions at \sqrt{s}=1.96~\TeV
We present measurements of the differential cross section dsigma/dpT_gamma
for the inclusive production of a photon in association with a b-quark jet for
photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for
photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is
the photon transverse momentum. The b-quark jets are required to have pT>15 GeV
and rapidity |y_jet| < 1.5. The results are based on data corresponding to an
integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the
Fermilab Tevatron Collider at sqrt(s)=1.96 TeV. The measured cross
sections are compared with next-to-leading order perturbative QCD calculations
using different sets of parton distribution functions as well as to predictions
based on the kT-factorization QCD approach, and those from the Sherpa and
Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.
Limits on anomalous trilinear gauge boson couplings from WW, WZ and Wgamma production in pp-bar collisions at sqrt{s}=1.96 TeV
We present final searches of the anomalous gammaWW and ZWW trilinear gauge
boson couplings from WW and WZ production using lepton plus dijet final states
and a combination with results from Wgamma, WW, and WZ production with leptonic
final states. The analyzed data correspond to up to 8.6/fb of integrated
luminosity collected by the D0 detector in pp-bar collisions at sqrt{s}=1.96
TeV. We set the most stringent limits at a hadron collider to date assuming two
different relations between the anomalous coupling parameters
Delta\kappa_\gamma, lambda, and Delta g_1^Z for a cutoff energy scale Lambda=2
TeV. The combined 68% C.L. limits are -0.057<Delta\kappa_\gamma<0.154,
-0.015<lambda<0.028, and -0.008<Delta g_1^Z<0.054 for the LEP parameterization,
and -0.007<Delta\kappa<0.081 and -0.017<lambda<0.028 for the equal couplings
parameterization. We also present the most stringent limits of the W boson
magnetic dipole and electric quadrupole moments.Comment: 10 pages, 5 figures, submitted to PL
Measurement of three-jet differential cross sections d sigma-3jet / d M-3jet in p anti-p collisions at sqrt(s)=1.96 TeV
We present the first measurement of the inclusive three-jet differential
cross section as a function of the invariant mass of the three jets with the
largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96
TeV. The measurement is made in different rapidity regions and for different
jet transverse momentum requirements and is based on a data set corresponding
to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at
the Fermilab Tevatron Collider. The results are used to test the three-jet
matrix elements in perturbative QCD calculations at next-to-leading order in
the strong coupling constant. The data allow discrimination between
parametrizations of the parton distribution functions of the proton.Comment: 10 pages, 4 figures, 2 tables, submitted to Phys. Lett. B, corrected
chi2 values for NNPD
Search for pair production of the scalar top quark in muon+tau final states
We present a search for the pair production of scalar top quarks
(), the lightest supersymmetric partners of the top quarks, in
collisions at a center-of-mass energy of 1.96 TeV, using data
corresponding to an integrated luminosity of {7.3 } collected with the
\dzero experiment at the Fermilab Tevatron Collider. Each scalar top quark is
assumed to decay into a quark, a charged lepton, and a scalar neutrino
(). We investigate final states arising from and
. With no significant excess of events observed above the
background expected from the standard model, we set exclusion limits on this
production process in the (,) plane.Comment: Submitted to Phys. Lett.
Measurements of inclusive W+jets production rates as a function of jet transverse momentum in ppbar collisions at sqrt{s}=1.96 TeV
This Letter describes measurements of inclusive W (--> e nu) + n jet cross
sections (n = 1-4), presented as total inclusive cross sections and
differentially in the nth jet transverse momentum. The measurements are made
using data corresponding to an integrated luminosity of 4.2 fb-1 collected by
the D0 detector at the Fermilab Tevatron Collider, and achieve considerably
smaller uncertainties on W +jets production cross sections than previous
measurements. The measurements are compared to next-to-leading order
perturbative QCD (pQCD) calculations in the n =1-3 jet multiplicity bins and to
leading order pQCD calculations in the 4-jet bin. The measurements are
generally in agreement with pQCD predictions, although certain regions of phase
space are identified where the calculations could be improved
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