505 research outputs found
Characterization of the Surface Finish of Machined Parts Using Artificial Vision and Hough Transform
Metabolic profiles of six African cultivars of cassava (Manihot esculenta Crantz) highlight bottlenecks of root yield
Open Access Article; Published online: 17 Jan 2020Cassava is an important staple crop in sub‐Saharan Africa, due to its high productivity even on nutrient poor soils. The metabolic characteristics underlying this high productivity are poorly understood including the mode of photosynthesis, reasons for the high rate of photosynthesis, the extent of source/sink limitation, the impact of environment, and the extent of variation between cultivars. Six commercial African cassava cultivars were grown in a greenhouse in Erlangen, Germany, and in the field in Ibadan, Nigeria. Source leaves, sink leaves, stems and storage roots were harvested during storage root bulking and analyzed for sugars, organic acids, amino acids, phosphorylated intermediates, minerals, starch, protein, activities of enzymes in central metabolism and yield traits. High ratios of RuBisCO:phosphoenolpyruvate carboxylase activity support a C3 mode of photosynthesis. The high rate of photosynthesis is likely to be attributed to high activities of enzymes in the Calvin–Benson cycle and pathways for sucrose and starch synthesis. Nevertheless, source limitation is indicated because root yield traits correlated with metabolic traits in leaves rather than in the stem or storage roots. This situation was especially so in greenhouse‐grown plants, where irradiance will have been low. In the field, plants produced more storage roots. This was associated with higher AGPase activity and lower sucrose in the roots, indicating that feedforward loops enhanced sink capacity in the high light and low nitrogen environment in the field. Overall, these results indicated that carbon assimilation rate, the K battery, root starch synthesis, trehalose, and chlorogenic acid accumulation are potential target traits for genetic improvement
Relaciones entre pH, aluminio y materia orgánica en algunos suelos de Colombia.
Se determinaron las relaciones existentes entre pH, el Al intercambiable y el contenido de materia orgánica en varios suelos del país. Se utilizaron los resultados de 833 análisis de suelos provenientes en su mayoría de las regiones naturales, dichos análisis se realizaron en el Laboratorio de Suelos del ICA, el Al intercambiable se determinó en suelos con pH inferior o igual a 5.5 y las muestras se agruparon de acuerdo a su contenido de materia orgánica, en 2 grupos: uno con contenido mayor del 10 por ciento y el otro, con contenido menor del 10 por ciento. Debido a que la mayoría de muestras provenían de las 3 regiones naturales: Cordilleras Andinas, Sabana de Bogotá y Llanos Orientales, sólo se presentan los resultados de las mismas, éstos demuestran que existe una relación inversa entre el contenido de Al y el pH, relación que es menos estrecha en los Llanos Orientales que en las otras 2 regiones naturales. En las Cordilleras Andinas y en la Sabana de Bogotá, las variaciones del pH debidas a la acción del Al no están afectadas por el contenido de materia orgánic
Organización de los filamentos de actina en células mioides peritubulares del túbulo seminífero de rata
Las células mioides peritubulares (MP) en roedores forman una monocapa entre dos láminas basales alrededor de los túbulos seminíferos (TS) y participan en la contracción
The symmetry of the superconducting order parameter in PuCoGa
The symmetry of the superconducting order parameter in single-crystalline
PuCoGa ( K) is investigated via zero- and transverse-
field muon spin relaxation (SR) measurements, probing the possible
existence of orbital and/or spin moments (time reversal-symmetry violation TRV)
associated with the superconducting phase and the in-plane magnetic-field
penetration depth in the mixed state, respectively. We find no
evidence for TRV, and show that the superfluid density, or alternatively,
, are for . Taken together these measurements are consistent with an even-parity
(pseudo-spin singlet), d-wave pairing state.Comment: 4 pages, 5 figure
Milagrito: a TeV air-shower array
Milagrito, a large, covered water-Cherenkov detector, was the world's first
air-shower-particle detector sensitive to cosmic gamma rays below 1 TeV. It
served as a prototype for the Milagro detector and operated from February 1997
to May 1998. This paper gives a description of Milagrito, a summary of the
operating experience, and early results that demonstrate the capabilities of
this technique.Comment: 38 pages including 24 figure
The Hubble Space Telescope PanCET Program:An Optical to Infrared Transmission Spectrum of HAT-P-32Ab
The cosmic ray positron excess and neutralino dark matter
Using a new instrument, the HEAT collaboration has confirmed the excess of
cosmic ray positrons that they first detected in 1994. We explore the
possibility that this excess is due to the annihilation of neutralino dark
matter in the galactic halo. We confirm that neutralino annihilation can
produce enough positrons to make up the measured excess only if there is an
additional enhancement to the signal. We quantify the `boost factor' that is
required in the signal for various models in the Minimal Supersymmetric
Standard Model parameter space, and study the dependence on various parameters.
We find models with a boost factor greater than 30. Such an enhancement in the
signal could arise if we live in a clumpy halo. We discuss what part of
supersymmetric parameter space is favored (in that it gives the largest
positron signal), and the consequences for other direct and indirect searches
of supersymmetric dark matter.Comment: 11 pages, 6 figures, matches published version (PRD
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