210 research outputs found
Observation of correlated-photon statistics using a single detector
We report experimental observations of correlated-photon statistics in the
single-photon detection rate. The usual quantum interference in a two-photon
polarization interferometer always accompanies a dip in the single detector
counting rate, regardless of whether a dip or peak is seen in the coincidence
rate. This effect is explained by taking into account all possible photon
number states that reach the detector, rather than considering just the state
post-selected by the coincidence measurement. We also report an
interferometeric scheme in which the interference peak or dip in coincidence
corresponds directly to a peak or dip in the single-photon detection rate.Comment: 4 pages, two-column (minor errors corrected.
Experimental Entanglement Concentration and Universal Bell-state Synthesizer
We report a novel Bell-state synthesizer in which an interferometric
entanglement concentration scheme is used. An initially mixed polarization
state from type-II spontaneous parametric down-conversion becomes entangled
after the interferometric entanglement concentrator. This Bell-state
synthesizer is universal in the sense that the output polarization state is not
affected by spectral filtering, crystal thickness, and, most importantly, the
choice of pump source. It is also robust against environmental disturbance and
a more general state, partially mixedpartially entangled state, can be
readily generated as well.Comment: Minor update (Newer data
Enhanced stability of layered phases in parallel hard-spherocylinders due to the addition of hard spheres
There is increasing evidence that entropy can induce microphase separation in
binary fluid mixtures interacting through hard particle potentials. One such
phase consists of alternating two dimensional liquid-like layers of rods and
spheres. We study the transition from a uniform miscible state to this ordered
state using computer simulations and compare results to experiments and theory.
We conclude that (1) there is stable entropy driven microphase separation in
mixtures of parallel rods and spheres, (2) adding spheres smaller then the rod
length decreases the total volume fraction needed for the formation of a
layered phase, therefore small spheres effectively stabilize the layered phase;
the opposite is true for large spheres and (3) the degree of this stabilization
increases with increasing rod length.Comment: 11 pages, 9 figures. Submitted to Phys. Rev. E. See related website
http://www.elsie.brandeis.ed
Estudio del efecto de los ácidos grasos poliinsaturados de la dieta: Mecanismos moleculares involucrados en la inflamación intestinal
The use of “omics” techniques in combination with model systems and molecular tools allows to understand how foods and food components act on metabolic pathways to regulate transcriptional processes. Polyunsaturated fatty acids have distinctive nutritional and metabolic effects because they give rise to lipid mediated products and affect the expression of various genes involved in intestinal inflammation. The present review focuses on the molecular effects of dietary polyunsaturated fatty acids on intestinal inflammation.El uso de técnicas «omic» en combinación con sistemas modelo y herramientas moleculares nos permiten entender como los alimentos y sus componentes actúan en las rutas metabólicas que regulan los procesos transcripcionales. Los ácidos grasos poliinsaturados tienen efectos nutricionales y metabólicos diferenciadores porque producen una elevación de los productos regulados por lípidos y afectan a la expresión de varios genes involucrados en la inflamación intestinal. La presente revisión se enfoca en los efectos moleculares de los ácidos grasos poliinsaturados de la dieta en la inflamación intestinal
Macromolecular theory of solvation and structure in mixtures of colloids and polymers
The structural and thermodynamic properties of mixtures of colloidal spheres
and non-adsorbing polymer chains are studied within a novel general
two-component macromolecular liquid state approach applicable for all size
asymmetry ratios. The dilute limits, when one of the components is at infinite
dilution but the other concentrated, are presented and compared to field theory
and models which replace polymer coils with spheres. Whereas the derived
analytical results compare well, qualitatively and quantitatively, with
mean-field scaling laws where available, important differences from ``effective
sphere'' approaches are found for large polymer sizes or semi-dilute
concentrations.Comment: 23 pages, 10 figure
Rubber's inclusion in zero-deforestation legislation is necessary but not sufficient to reduce impacts on biodiversity
Agricultural commodity production is a major driver of tropical deforestation and biodiversity loss. Natural rubber from Hevea brasiliensis, a valuable commodity without viable substitutes, has recently been included in the European Union (EU) deforestation regulation that aims to halt imports of goods containing embedded deforestation. Sustained growth in demand for rubber is driven by increasing tire production, caused by rising transport flows and personal car ownership. We show that average natural rubber yields remain static, meaning 2.7–5.3 million ha of additional plantations could be needed by 2030 to meet demand. A systematic literature search identified 106 case studies concerning transitions to and from rubber, revealing that substantial rubber plantation area expansion since 2010 has occurred at the expense of natural forest. Eliminating deforestation from rubber supply chains requires support for millions of smallholder growers to maintain or increase production from existing plantations, without land or water degradation. Supply chain traceability efforts offer opportunities to deliver such support. While the inclusion of rubber in EU legislation is a positive step, it is critical to ensure that smallholders are not marginalized to avoid exacerbating poverty, and that other markets follow suit to avoid displacement of rubber-driven deforestation to unregulated markets
Reliability of the beamsplitter based Bell-state measurement
A linear 50/50 beamsplitter, together with a coincidence measurement, has
been widely used in quantum optical experiments, such as teleportation, dense
coding, etc., for interferometrically distinguishing, measuring, or projecting
onto one of the four two-photon polarization Bell-states . In
this paper, we demonstrate that the coincidence measurement at the output of a
beamsplitter cannot be used as an absolute identifier of the input state
nor as an indication that the input photons have projected to
the state.Comment: 4 pages, two-colum
Residual stress, strain and faults in nanocrystalline palladium and copper
Nanocrystalline Pd and Cu, prepared by inert gas condensation and warm compaction, were studied using x-ray diffraction techniques. A sample of Cu with sub-micrometer grain size produced by severe plastic deformation was also examined. The Warren-Averbach technique was used to separate the line broadening due to grain size, root-mean-squared strain, and faults. Peak shifts and asymmetry were used to determine the long range surface stresses, stacking fault probability, and twin probability. The Young`s modulus of a Pd sample was determined by an ultrasonic technique, and compared with the coarse-grained, fully-dense value
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