982 research outputs found
Level and length of cyclic solar activity during the Maunder minimum as deduced from the active day statistics
The Maunder minimum (MM) of greatly reduced solar activity took place in
1645-1715, but the exact level of sunspot activity is uncertain as based, to a
large extent, on historical generic statements of the absence of spots on the
Sun. Here we aim, using a conservative approach, to assess the level and length
of solar cycle during the Maunder minimum, on the basis of direct historical
records by astronomers of that time. A database of the active and inactive days
(days with and without recorded sunspots on the solar disc respectively) is
constructed for three models of different levels of conservatism (loose ML,
optimum MO and strict MS models) regarding generic no-spot records. We have
used the active day fraction to estimate the group sunspot number during the
MM. A clear cyclic variability is found throughout the MM with peaks at around
1655--1657, 1675, 1684 and 1705, and possibly 1666, with the active day
fraction not exceeding 0.2, 0.3 or 0.4 during the core MM, for the three
models. Estimated sunspot numbers are found very low in accordance with a grand
minimum of solar activity.
We have found, for the core MM (1650-1700), that: (1) A large fraction of
no-spot records, corresponding to the solar meridian observations, may be
unreliable in the conventional database. (2) The active day fraction remained
low (below 0.3-0.4) throughout the MM, indicating the low level of sunspot
activity. (3) The solar cycle appears clearly during the core MM. (4) The
length of the solar cycle during the core MM appears years, but there
is an uncertainty in that. (5) The magnitude of the sunspot cycle during MM is
assessed to be below 5-10 in sunspot numbers;
A hypothesis of the high solar cycles during the MM is not confirmed.Comment: Accepted to Astron. Astrophy
Pulsed electric fields to improve the use of non-saccharomyces starters in red wines
New nonthermal technologies, including pulsed electric fields (PEF), open a new way to generate more natural foods while respecting their organoleptic qualities. PEF can reduce wild yeasts to improve the implantation of other yeasts and generate more desired metabolites. Two PEF treatments were applied; one with an intensity of 5 kV/cm was applied continuously to the must for further colour extraction, and a second treatment only to the must (without skins) after a 24-hour maceration of 17.5 kV/cm intensity, reducing its wild yeast load by up to 2 log CFU/mL, thus comparing the implantation and fermentation of inoculated non-Saccharomyces yeasts. In general, those treated with PEF preserved more total esters and formed more anthocyanins, including vitisin A, due to better implantation of the inoculated yeasts. It should be noted that the yeast Lachancea thermotolerans that had received PEF treatment produced four-fold more lactic acid (3.62 ± 0.84 g/L) than the control of the same yeast, and Hanseniaspora vineae with PEF produced almost three-fold more 2-phenylethyl acetate than the rest. On the other hand, 3-ethoxy-1-propanol was not observed at the end of the fermentation with a Torulaspora delbrueckii (Td) control but in the Td PEF, it was observed (3.17 ± 0.58 mg/L)
Expanding the dynamic range of flat-panel detectors used in small-animal cone-beam CT: an automated dual-exponsure technique
[Poster] 4th European Molecular Imaging Meeting, Barcelona, Spain, May 27 - 30, 2009This work is supported in part by Ministerio de Ciencia e Innovación (TEC2008-06715 and TEC2007-64731), EU-FP7 project FMTXCT-201792 and CD-TEAM project (CENIT program).Publicad
Simulation of mechanical misalignments in a cone-beam micro-CT system
Proceeding of: 2008 IEEE Nuclear Science Symposium Conference Record (NSS '08), Dresden, Germany, 19-25 October 2008X-ray CT images usually show artefacts due not only to physical effects -e.g., beam hardening-, but also to misalignments that remain after mechanical calibration. These
artefacts become particularly noticeable in the case of high spatial resolution systems and in hybrid systems, such as PETCT,
SPECT-CT scanners, which rely on a correct registration of emission and CT data. Hence, slight mechanical misalignments affect the quality of the CT images and any attenuation
correction methods or further quantification based on them. We implemented a computer simulator of these artefacts on a conebeam,
flat-panel based micro-CT scanner. Using this simulator, we studied the effect of these different misalignments (pitch and
roll tilts, skew and shifts) on reconstructed images.This work is partially funded by the CD-TEAM Project, CENIT Program, Spanish Ministerio de Industria, and with grants from the Ministerio de Educaci6n y Ciencia, projects TEC200764731 and TEC2008-06715-C02-01
On the organization of the nucleosomes associated with telomeric sequences
AbstractThe functions of telomeres and, probably, of interstitial telomeric sequences (ITSs) are influenced by their chromatin structure and organization. Telomeres in higher eukaryotes fold into nucleosomes that are about 20–40 bp shorter than the nucleosomes associated with bulk chromatin. Although the functional relevance of this short nucleosomal organization remains unknown, it is believed that short nucleosomes should contribute to telomere function. Whereas telomeric nucleosomes have been widely studied in different organisms, very little is known about the nucleosomal organization of ITSs. Chinese hamster ITSs have been found to associate with short nucleosomes. However, we have found that Arabidopsis thaliana ITSs fold into nucleosomes that have a repeat length similar to bulk chromatin. We discuss how the primary sequence of telomeres and ITSs could influence their nucleosomal organization
Fracturas epifisiolisis graves de la extremidad proximal del radio: resultado tras tratamiento quirúrgico
La fractura-epifisiolisis del cuello radial es una lesión grave que puede
originar alteracione s en e l crecimiento epifisario. Presentamo s una seri e de 22 casos
revisados con una antigüedad mínima de dos años. Fueron intervenidos 14 pacientes,
de los que 10 estaban incluidos en el grupo III o en lesione s de Jeffery. Once enfermos
fueron tratado s con cirugí a abierta. Cuando l a intervenció n consisti ó en reducció n
abierta y osteosíntesis, los resultados clínicos fueron buenos en el 50%, pero cuando só-
lo se practicó reducción cruenta sin asociar sistema estabilizador metálico, éstos llegaron
al 100%. En cinco de los ocho paciente s del primer grupo se presentaron calcificacione
s articulares y en dos, epifisiodesis. En el segundo grupo no aparecieron ninguna
de éstas alteraciones. Creemos que en los casos de fracturas epifisiolisis del cuello radial
en niños con gran desplazamiento, el tratamiento ideal es la cuidadosa reducción
cruenta evitando fijación con aguja.The fracture epiphysiolysis of radial neck is a grave lesion which may
induc e epiphysea l grown disturbances. A review of 22 case s suffering such fracture s
was carried out with a mean follow-up of 2 years. Of the total, 14 cases wer e treated by
surgery, 10 of thes e showing either type III or Jeffery's fractures. Eleven patients reequired
open reduction. In 50% of the cases treated by open reduction and internal fixation,
the clinical results wer e satisfactory. When internal fixation was not used, the satisfactory
results reached 100%. Five of the 8 cases of the firt groups developed periarticular
ossifications and 2 othe r showed epiphyseal closening. Thes e type of complications
wer e not seen in the second group. For epiphysiolysis of the radial neck with sever
e displacement. The ideal treatment seems to be a careful open reduction avoiding
internal fixation
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