1,051 research outputs found
Optimized production of large Bose Einstein Condensates
We suggest different simple schemes to efficiently load and evaporate a
''dimple'' crossed dipolar trap. The collisional processes between atoms which
are trapped in a reservoir load in a non adiabatic way the dimple. The
reservoir trap can be provided either by a dark SPOT Magneto Optical Trap, the
(aberrated) laser beam itself or by a quadrupolar or quadratic magnetic trap.
Optimal parameters for the dimple are derived from thermodynamical equations
and from loading time, including possible inelastic and Majorana losses. We
suggest to load at relatively high temperature a tight optical trap. Simple
evaporative cooling equations, taking into account gravity, the possible
occurrence of hydrodynamical regime, Feshbach resonance processes and three
body recombination events are given. To have an efficient evaporation the
elastic collisional rate (in s) is found to be on the order of the
trapping frequency and lower than one hundred times the temperature in
micro-Kelvin. Bose Einstein condensates with more than atoms should be
obtained in much less than one second starting from an usual MOT setup.Comment: 14 page
Two Measures of Non-Probabilistic Uncertainty
There are two reasons why uncertainty about the future yield of investments
may not be adequately described by Probability Theory. The first one is due to
unique or nearly-unique events, that either never realized or occurred too
seldom for probabilities to be reliable. The second one arises when when one
fears that something may happen, that one is not even able to figure out, e.g.,
if one asks: "Climate change, financial crises, pandemic, war, what next?"
In both cases, simple one-to-one causal mappings between available
alternatives and possible consequences eventually melt down. However, such
destructions reflect into the changing narratives of business executives,
employees and other stakeholders in specific, identifiable and differential
ways. In particular, texts such as consultants' reports or letters to
shareholders can be analysed in order to detect the impact of both sorts of
uncertainty onto the causal relations that normally guide decision-making.
We propose structural measures of causal mappings as a means to measure
non-probabilistic uncertainty, eventually suggesting that automated text
analysis can greatly augment the possibilities offered by these techniques.
Prospective applications may concern statistical institutes, stock market
traders, as well as businesses wishing to compare their own vision to those
prevailing in their industry.Comment: 22 pages, 15 figure
Yield and Forage Quality in Alfalfa-Weeping Lovegrass Mixtures
Little is known about the relative performance of weeping lovegrass in mixtures with alfalfa. Our objective was to compare the productivity and forage quality of monocultures and binary mixtures of the species. Mixtures always gave higher yields than any of the monocultures and the highest was obtained in the mixture with the largest proportion of alfalfa. In the second year weeping lovegrass N concentration in the mixtures were higher than in monoculture. Weeping lovegrass did not affect the alfalfa N concentration. There was not differences in the NDF, for between these species
Micropropagation of Glandularia, native genus with ornamental potencial
En este trabajo se estableció un protocolo
de propagación in vitro de tres especies
nativas del género Glandularia: G. peruviana,
G. sp. y G. laciniata. Para el establecimiento in
vitro se evaluó el medio de Murashige Skoog
(MS) con macro y micronutrientes diluidos a
la mitad adicionado con 0,05 μM de bencilaminopurina
(BAP) sola o en combinación con
0,1 μM thiadiazuron (TDZ) y un testigo sin
reguladores del crecimiento. En la etapa de
multiplicación se evaluó el medio de cultivo
MS diluido a la ½ ó ¼ y adicionado de 20 ó
40 gr.L-1 de sacarosa. Es posible establecer y
micropropagar estas especies en medios de
cultivo sencillos. El medio más eficiente para
el establecimiento fue aquel sin reguladores,
mientras que el más adecuado para la multiplicación
fue MS ½ adicionado de 20 gr.L-1 de
sacarosa, en el cual la tasa de multiplicación
cada 30 dÃas fue de 6 en G. sp. y G. peruviana
y 4 para G. laciniata.In this work there was established a protocol
of microspropagation of three native species
of the genus Glandularia, G. peruviana, G.
sp. and G. laciniata. Macro and micronutrients
half strength Murashige Skoog (MS) media
added with BAP 0.05 μM alone or in combination
with TDZ 0.1 μM were tested in the
establishment stage. Half and quarter strength
MS media with 20 or 40 g.L-1 of sucrose were
assayed at multiplication stage. It is possible to
establish and to micropropagate these species
in simple culturing media. The most efficient
media for establishment stage was that one
without growth regulators, whereas the most
suitable for the multiplication it was MS ½
with 20 g.L-1 of sucrose, where the multiplication
rate every 30 days were 6 for G. sp and
G. peruviana and 4 for G. laciniata.Fil: Ponce, MarÃa T..
Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias BiológicasFil: Guiñazú, Mónica E..
Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias BiológicasFil: Fioretti, Sonia B..
Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Producción AgropecuariaFil: Cirrincione, Miguel A..
Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Biológica
Primary structure of a protease isoinhibitor from bovine spleen. A possible intermediate in the processing of the primary gene product.
Sequence studies on the protease isoinhibitor I isolated from bovine spleen have revealed that it consists of two molecular variants which differ only in the presence of an additional COOH-terminal residue, asparagine, in the less abundant form. The complete amino acid sequence shows that they are composed of 65 or 66 residues and predicts Mr of 7223 or 7338, respectively. The sequences correspond exactly to the 58-residue polypeptide chain of spleen isoinhibitor II plus NH2- and COOH-terminal extensions of 2 and 5 or 6 amino acid residues, respectively. Moreover the entire sequences are located within the 100-residue structure deduced from the mRNA and DNA sequences of the putative precursor. These data support the idea that the molecular variants of isoinhibitor I are either mature proteins with distinct functional roles, or intermediates in the multistage processing of the primary product of gene expression, which eventually leads to the mature protein, i.e. inhibitor II
Enhancement of the formation of ultracold Rb molecules due to resonant coupling
We have studied the effect of resonant electronic state coupling on the
formation of ultracold ground-state Rb. Ultracold Rb molecules
are formed by photoassociation (PA) to a coupled pair of states,
and , in the region below the
limit. Subsequent radiative decay produces high vibrational levels of the
ground state, . The population distribution of these state
vibrational levels is monitored by resonance-enhanced two-photon ionization
through the state. We find that the populations of vibrational
levels =112116 are far larger than can be accounted for by the
Franck-Condon factors for transitions with
the state treated as a single channel. Further, the
ground-state molecule population exhibits oscillatory behavior as the PA laser
is tuned through a succession of state vibrational levels. Both of
these effects are explained by a new calculation of transition amplitudes that
includes the resonant character of the spin-orbit coupling of the two
states. The resulting enhancement of more deeply bound ground-state molecule
formation will be useful for future experiments on ultracold molecules.Comment: 6 pages, 5 figures; corrected author lis
Aluminum modulation of proteolytic activities
The effect of aluminum ions on the activity of proteolyic activities, mainly serine proteases and calpains, has been examined. Aluminum affects the biological activity of proteolytic activities either through a direct effect on the enzyme molecule or through a deregulation of the control mechanisms acting on them. Binding of the ion, most likely results in molecular rearrangements affecting both the substrates binding site and the site involved in the recognition of macromolecular inhibitors. As whole, the data reported clearly indicate that aluminum significatively affects the intracellular protein turnover, most likely triggering catastrophic events for the cellular life. The physiopathological significance of these effects has been discussed, in particular for neurological disorders (the Alzheimer's disease included) where an imbalance of proteolytic as well as antiproteolytic systems appears a crucial event both for the formation of neuritic plaques and neurofibrillary tangles which are the major hallmarks of the disease. © 2002 Elsevier Science B.V. All rights reserved
A Unique Amphibole- and Magnetite-Rich Carbonaceous Chondrite from Almahata Sitta
Almahata Sitta (AhS) 202 from the UoK collection represents a clast from the polymict breccia asteroid 2008 TC3. AhS 202 was recognized as a unique carbonaceous chondrite (CC) with a high magnetite content. Here we report that it also contains a significant amount of amphibole, a mineral that is very rare in chondrites and has not previously been reported in significant abundance in a CC. We present new petrographic, oxygen isotope, and micro-FTIR data. We discuss petrogenesis and possible relationships to known CC
- …