53 research outputs found
P. FARNÉS SCHERER, Construir y adaptar las Iglesias. Orientaciones y sugerencias prácticas sobre el espacio celebrativo, según el espíritu del Concilio Vaticano II, Ed. Regina, Barcelona 1989, 272 pp., 13 x 19,5. [RECENSIÓN]
We study the growth of two- and three-body correlations in an ultracold Bose gas quenched to unitarity. This is encoded in the dynamics of the two- and three-body contacts analyzed in this work. Via a set of relations connecting many-body correlations dynamics with few-body models, signatures of the Efimov effect are mapped out as a function of evolution time at unitarity over a range of atomic densities . For the thermal resonantly interacting Bose gas, we find that atom-bunching leads to an enhanced growth of few-body correlations. These atom-bunching effects also highlight the interplay between few-body correlations that occurs before genuine many-body effects enter on Fermi timescales
Influence of random roughness on the Casimir force at small separations
The influence of random surface roughness of Au films on the Casimir force is
explored with atomic force microscopy in the plate-sphere geometry. The
experimental results are compared to theoretical predictions for separations
ranging between 20 and 200 nm. The optical response and roughness of the Au
films were measured and used as input in theoretical predictions. It is found
that at separations below 100 nm, the roughness effect is manifested through a
strong deviation from the normal scaling of the force with separation distance.
Moreover, deviations from theoretical predictions based on perturbation theory
can be larger than 100%.Comment: 18, 5 figure
Characterization of optical properties and surface roughness profiles: The Casimir force between real materials
The Lifshitz theory provides a method to calculate the Casimir force between
two flat plates if the frequency dependent dielectric function of the plates is
known. In reality any plate is rough and its optical properties are known only
to some degree. For high precision experiments the plates must be carefully
characterized otherwise the experimental result cannot be compared with the
theory or with other experiments. In this chapter we explain why optical
properties of interacting materials are important for the Casimir force, how
they can be measured, and how one can calculate the force using these
properties. The surface roughness can be characterized, for example, with the
atomic force microscope images. We introduce the main characteristics of a
rough surface that can be extracted from these images, and explain how one can
use them to calculate the roughness correction to the force. At small
separations this correction becomes large as our experiments show. Finally we
discuss the distance upon contact separating two rough surfaces, and explain
the importance of this parameter for determination of the absolute separation
between bodies.}Comment: 33 pages, 14 figures, to appear in Springer Lecture Notes in Physics,
Volume on Casimir Physics, edited by Diego Dalvit, Peter Milonni, David
Roberts, and Felipe da Ros
Influence of roughness on capillary forces between hydrophilic surfaces
Capillary forces have been measured by Atomic Force Microscopy in the
plate-sphere setup between gold, borosilicate glass, GeSbTe, titanium, and UV
irradiated amorphous titaniumdioxide surfaces. The force measurements were
performed as a function contact time and surface roughness in the range 0.2 -
15 nm rms, and relative humidity ranging between 2 and 40 %. It is found that
even for the lowest attainable relative humidity 2 % very large capillary
forces are still present. The latter suggests the persistence of a nanometers
thick adsorbed water layer that acts as a capillary bridge between contacting
surfaces. Moreover, we found a significantly different scaling behavior of the
force with rms roughness for materials with different hydrophilicity as
compared to gold-gold surfaces
Bunching, clustering, and the buildup of few-body correlations in a quenched unitary Bose gas
We study the growth of two- and three-body correlations in an ultracold Bose gas quenched to unitarity. This is encoded in the dynamics of the two- and three-body contacts analyzed in this work. Via a set of relations connecting many-body correlations dynamics with few-body models, signatures of the Efimov effect are mapped out as a function of evolution time at unitarity over a range of atomic densities . For the thermal resonantly interacting Bose gas, we find that atom-bunching leads to an enhanced growth of few-body correlations. These atom-bunching effects also highlight the interplay between few-body correlations that occurs before genuine many-body effects enter on Fermi timescales
Fetal exposure to bisphenols and phthalates and childhood bone mass: a population-based prospective cohort study.
Background: Exposure to bisphenols and phthalates might influence bone health. We hypothesized that exposure to bisphenols and phthalates during fetal life has persistent effects on bone development. Objectives: To analyze the associations of fetal exposure to bisphenols and phthalates with bone health in school-aged children. Methods: Among 1,362 mother-child pairs participating in a population-based cohort study, we measured maternal urinary concentrations of bisphenols and phthalates at first, second and third trimester with high performance liquid chromatography electrospray ionizatio
Effects of neonatal enteral glutamine supplementation on cognitive, motor and behavioural outcomes in very preterm and/or very low birth weight children at school age
Novel highly integrated biodiesel production technology in a centrifugal contactor separator device
Значение мотивации персонала на предприятии
Основная цель – систематизировать сведения о мотивации персонала и
его значении на предприятии
Population-Specific Responses to Interspecific Competition in the Gut Microbiota of Two Atlantic Salmon (Salmo salar) Populations
The gut microbial community in vertebrates plays a role in nutrient digestion and absorption, development of intestine and immune systems, resistance to infection, regulation of bone mass and even host behavior and can thus impact host fitness. Atlantic salmon (Salmo salar) reintroduction efforts into Lake Ontario, Canada, have been unsuccessful, likely due to competition with non-native salmonids. In this study, we explored interspecific competition effects on the gut microbiota of two Atlantic salmon populations (LaHave and Sebago) resulting from four non-native salmonids. After 10 months of rearing in semi-natural stream tanks under six interspecific competition treatments, we characterized the gut microbiota of 178 Atlantic salmon by parallel sequencing the 16S rRNA gene. We found 3978 bacterial OTUs across all samples. Microbiota alpha diversity and abundance of 27 OTUs significantly differed between the two populations. Interspecific competition reduced relative abundance of potential beneficial bacteria (six genera of lactic acid bacteria) as well as 13 OTUs, but only in the LaHave population, indicating population-specific competition effects. The pattern of gut microbiota response to interspecific competition may reflect local adaptation of the host-microbiota interactions and can be used to select candidate populations for improved species reintroduction success
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