9,476 research outputs found
Cold-electron bolometers for future mm and sub-mm sky surveys
Future sky surveys in the mm/sub-mm range, like the forthcoming balloon-borne
missions LSPE, OLIMPO, SPIDER etc., will need detectors insensitive to cosmic
rays (CRs) and with a NEP of the order of W/sqrt(Hz).
The Cold-Electron Bolometers (CEBs) technology is promising, having the
required properties, since the absorber volume is extremely small and the
electron system of the absorber is thermally insulated from the phonon system.
We have developed an experimental setup to test the optical performance and the
CRs insensitivity of CEBs, with the target of integrating them in the OLIMPO
and LSPE focal planes.Comment: 6 figure
Telephone-cord instabilities in thin smectic capillaries
Telephone-cord patterns have been recently observed in smectic liquid crystal
capillaries. In this paper we analyse the effects that may induce them. As long
as the capillary keeps its linear shape, we show that a nonzero chiral
cholesteric pitch favors the SmA*-SmC* transition. However, neither the
cholesteric pitch nor the presence of an intrinsic bending stress are able to
give rise to a curved capillary shape.
The key ingredient for the telephone-cord instability is spontaneous
polarization. The free energy minimizer of a spontaneously polarized SmA* is
attained on a planar capillary, characterized by a nonzero curvature. More
interestingly, in the SmC* phase the combined effect of the molecular tilt and
the spontaneous polarization pushes towards a helicoidal capillary shape, with
nonzero curvature and torsion.Comment: Submitte
The emergence of AdS(2) from quantum fluctuations
We have shown how the quantization of two-dimensional quantum gravity with an
action which contains only a positive cosmological constant and boundary
cosmological constants leads to the emergence of a spacetime which can be
described as a constant negative curvature spacetime with superimposed quantum
fluctuations.Comment: 4 pages. Talk given by W. Westra at the Eleventh Marcel Grossmann
Meeting on General Relativity at the Freie U. Berlin, July 23 - 29, 200
Interfaces and the edge percolation map of random directed networks
The traditional node percolation map of directed networks is reanalyzed in
terms of edges. In the percolated phase, edges can mainly organize into five
distinct giant connected components, interfaces bridging the communication of
nodes in the strongly connected component and those in the in- and
out-components. Formal equations for the relative sizes in number of edges of
these giant structures are derived for arbitrary joint degree distributions in
the presence of local and two-point correlations. The uncorrelated null model
is fully solved analytically and compared against simulations, finding an
excellent agreement between the theoretical predictions and the edge
percolation map of synthetically generated networks with exponential or
scale-free in-degree distribution and exponential out-degree distribution.
Interfaces, and their internal organization giving place from "hairy ball"
percolation landscapes to bottleneck straits, could bring new light to the
discussion of how structure is interwoven with functionality, in particular in
flow networks.Comment: 20 pages, 4 figure
"All on short" prosthetic-implant supported rehabilitations
Objectives. Short implants are increasing their popularity among clinicians who want to fulfill the constant demanding of fixed prosthetic solutions in edentulous jaws. The aim of this report was to propose a new possibility to project and realize an occlusal guided implant cross-arch prosthesis supported by ultra-short implants, describing it presented an edentulous mandible case report. Methods. A 61-year-old, Caucasian, female patient who attended the dental clinic of the University of L’Aquila presented with edentulous posterior inferior jaw and periodontitis and periimplantitis processes in the anterior mandible. The remaining tooth and the affected implant were removed. Six 4-mm-long implants were placed to support a cross-arch metal-resin prosthesis. Results. At 1-year follow-up clinical and radiological assessment showed a good osseointegration of the fixtures and the patient was satisfied with the prosthesis solution. Conclusion. The method, even if it requires further validation, seems to be a valid aid in solving lower edentulous clinical cases, and appears less complex and with more indications of other proposals presented in the current clinical literature. Our case report differs from the current technique All-on-Four, which uses four implants in the mandible to support overdenture prosthesis, assuring a very promising clinical resul
Photonic applications of azobenzene molecules embedded in amorphous polymer
AbstractThe incorporation of azobenzene chromophores into polymer systems gives rise to a number of unique effects under UV and visible light irradiation. The light-driven isomerization of the azobenzene element acts as a light-to-mechanical energy converter, translating the nanoscopic structural movement of the isomerization azobenzene into macroscopic topographic film modulation in the form of surface relief. This review focuses on the study of reversible changes in shape in various systems incorporating azobenzene, including large-scale superficial photo-patterned glassy materials, light-driven reshaping of tridimensional superficial azo-textures and contractions of stimuli-responsive liquid crystalline networks (LCNs). Further, promising applications of azo systems are investigated as smart biointerfaces able to mimic time-varying biological systems
On the Fe abundance peak formation in cool-core clusters of galaxies: hints from cluster WARPJ1415.1+3612 at z=1.03
We present a detailed study of the iron content of the core of the
high-redshift cluster WARPJ1415.1+3612 (z=1.03). By comparing the central Fe
mass excess observed in this system, M_Fe^exc = (1.67 +/- 0.40) x 10^9 M_sun,
with those measured in local cool-core systems, we infer that the bulk of the
mass excess was already in place at z=1, when the age of the Universe was about
half of what it is today. Our measures point to an early and intense period of
star formation most likely associated with the formation of the BCG. Indeed, in
the case of the power-law delay time distribution with slope -1, which
reproduces the data of WARPJ1415.1+3612 best, half of the supernovae explode
within 0.4 Gyr of the formation of the BCG. Finally, while for local cool-core
clusters the Fe distribution is broader than the near infrared light
distribution of the BCG, in WARPJ1415.1+3612 the two distributions are
consistent, indicating that the process responsible for broadening the Fe
distribution in local systems has not yet started in this distant cluster.Comment: 10 pages, accepted for publication in A&A, minor language corrections
added in v
Enhancing the Violation of the Einstein-Podolsky-Rosen Local Realism by Quantum Hyper-entanglement
Mermin's observation [Phys. Rev. Lett. {\bf 65}, 1838 (1990)] that the
magnitude of the violation of local realism, defined as the ratio between the
quantum prediction and the classical bound, can grow exponentially with the
size of the system is demonstrated using two-photon hyper-entangled states
entangled in polarization and path degrees of freedom, and local measurements
of polarization and path simultaneously.Comment: Minor errors corrected. To appear on Physical Review Letter
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