1,591 research outputs found
Discovery of Very High Energy gamma - ray emission from the extreme BL Lac object H2356-309 with H.E.S.S
The understanding of acceleration mechanisms in active galactic nuclei (AGN)
jets and the measurement of the extragalactic-background-light (EBL) density
are closely linked and require the detection of a large sample of
very-high-energy (VHE) emitting extragalactic objects at varying redshifts. We
report here on the discovery with the H.E.S.S. (High Energy Stereoscopic
System) atmospheric-Cherenkov telescopes of the VHE Gamma-ray emission from
H2356 - 309, an extreme BL Lac object located at a redshift of 0.165. The
observations of this object, which was previously proposed as a
southern-hemisphere VHE candidate source, were performed between June and
December 2004. The total exposure is 38.9 hours live time, after data quality
selection, which yields the detection of a signal at the level of 9.0
(standard deviations) .Comment: To appear on proceeding of 29th International Cosmic Ray Conference
(ICRC 2005
On Hirschman and log-Sobolev inequalities in mu-deformed Segal-Bargmann analysis
We consider a deformation of Segal-Bargmann space and its transform. We study
L^p properties of this transform and obtain entropy-entropy inequalities
(Hirschman) and entropy-energy inequalities (log-Sobolev) that generalize the
corresponding known results in the undeformed theory.Comment: 42 pages, 3 figure
A self-assembly based supramolecular bioink with hierarchical control As a new bioprinting tool
Tissue engineering aims to capture details of the extracellular matrix (ECM) that stimulate cell growth and tissue regeneration. Molecularly complex materials or advanced additive fabrication techniques are often used to capture aspects of the ECM. Promising biofabrication techniques often lack nano and molecular scale control, as well as materials that can recreate the natural ECM or selectively guide cell behaviour. On the other hand, complex biomaterials based on molecular self-assembly tend to lack reproducibility and order beyond the nanoscale. We propose a new material fabrication platform that integrates the benefits of bioprinting and molecular self-assembly to overcome the current major limitations. Our approach relies on the co-assembly of peptide amphiphiles (PAs) with biomolecules and/or proteins found in the ECM, whilst exploiting the droplet-on-demand (DoD) printing process. Taking advantage of the interfacial fluid forces during printing, it is possible to guide the self-assembly into aligned or disordered nanofibers, hydrogel structures of different geometries and sizes, surface topographies and higher-ordered structures made from multiple hydrogels. The co-assembly process can be performed during printing and in cell-friendly conditions, whilst exhibiting high cell viability (\u3e 88 %). Moreover, multiple cell types can be spatially distributed on the outside or embedded within the tuneable biomimetic scaffolds. The combination of self-assembly with 3D-bioprinting, provides a basis for a new biofabrication platform to create hydrogels of complex geometry, structural hierarchy and tuneable chemical composition.
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New Physics searches in a low threshold scintillating argon bubble chamber measuring coherent elastic neutrino-nucleus scattering in reactors
The sensitivity to New Physics of a low threshold scintillating argon bubble
chamber measuring coherent elastic neutrino-nucleus scattering in reactors is
reported. Namely, light scalar mediators, sterile neutrino oscillations,
unitarity violation, and non-standard interactions are studied. The results
indicate that this detector could be able to set stronger constraints than
current limits set by the recent COHERENT measurements. Considering the best
scenario, a 100 kg detector located 30 m from a 2000 MW reactor, a
sterile neutrino search would cover most of the space parameter allowed from
the reactor anti-neutrino anomaly fit. Unitarity violation studies could set
constraints on more stringent than the current oscillation
experiments fit. A low threshold argon detector with very low backgrounds has
the potential to explore New Physics in different scenarios and set competitive
constraints
A Spectacular VHE Gamma-Ray Outburst from PKS 2155-304 in 2006
Since 2002 the VHE (>100 GeV) gamma-ray flux of the high-frequency peaked BL
Lac PKS 2155-304 has been monitored with the High Energy Stereoscopic System
(HESS). An extreme gamma-ray outburst was detected in the early hours of July
28, 2006 (MJD 53944). The average flux above 200 GeV observed during this
outburst is ~7 times the flux observed from the Crab Nebula above the same
threshold. Peak fluxes are measured with one-minute time scale resolution at
more than twice this average value. Variability is seen up to ~600 s in the
Fourier power spectrum, and well-resolved bursts varying on time scales of ~200
seconds are observed. There are no strong indications for spectral variability
within the data. Assuming the emission region has a size comparable to the
Schwarzschild radius of a ~10^9 solar mass black hole, Doppler factors greater
than 100 are required to accommodate the observed variability time scales.Comment: 4 pages, 3 figures; To appear in the Proceedings of the 30th ICRC
(Merida, Mexico
Estimación de los términos de transferencia de masa en la recuperación de licopeno empleando aceite de Moringa oleifera Lam como solvente
The aim of this work was to assess the terms associated with mass transfer in the lycopene recovery from the waste of a tomato canning plant. Moringa oleifera Lam oil was employed as solvent. An ultrasonic extraction was carried out on skin and seeds. The operational variables were temperature (skin: 45, 60, 75, 90 ºC; seed: 45, 60, 75 ºC), matrix/solvent ratio (m/v) (1:20, 1:25, 1:30), particle size (skin: < 1, 1-2, > 3.15 mm; seed: < 1, 1-2, > 2 mm) and extract separation method (filtration and centrifugation). Kinetic constant, lycopene concentration on the solid surface, volumetric coefficient of mass transfer and effective diffusivity were determined. The more the kinetic constant increased, the higher the volumetric coefficient of mass transfer was. Effective diffusivity increased with temperature. Activation energy values suggest a possible deterioration of lycopene at temperatures higher than the optimum. The use of M. oleifera oil as solvent should increase the biological value of the lycopene extracts.El objetivo del presente trabajo fue evaluar los términos asociados a la transferencia de masa en la extracción de licopeno a partir del residuo de la industria de conservas de tomate. Como solvente se utilizó aceite de Moringa oleífera Lam. Se realizó una extracción ultrasónica sobre piel y semillas. Las variables operacionales investigadas fueron, temperatura (piel: 45, 60, 75, 90 ºC; semillas: 45, 60, 75 ºC), relación soluto/solvente (m/v) (1:20, 1:25, 1:30), tamaño de partícula (piel: <1, 1-2, >3.15 mm; semilla: <1, 1-2, >2 mm) y métodos de separación del extracto (filtración y centrifugación). Se determinaron la constante cinética, la concentración de licopeno en la superficie del sólido, el coeficiente volumétrico de transferencia de masa y la difusividad efectiva. A mayor contante cinética, mayor coeficiente volumétrico de transferencia de masa. La difusividad efectiva aumentó con la temperatura. Los valores de energía de activación sugieren un posible deterioro del licopeno a temperaturas superiores a las óptimas. El uso del aceite de M. oleífera como solvente debe incrementar el valor biológico de los extractos de licopeno
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