25,330 research outputs found
Sub-10 nm colloidal lithography for integrated spin-photo-electronic devices
Colloidal lithography [1] is how patterns are reproduced in a variety of
natural systems and is used more and more as an efficient fabrication tool in
bio-, opto-, and nano-technology. Nanoparticles in the colloid are made to form
a mask on a given material surface, which can then be transferred via etching
into nano-structures of various sizes, shapes, and patterns [2,3]. Such
nanostructures can be used in biology for detecting proteins [4] and DNA [5,6],
for producing artificial crystals in photonics [7,8] and GHz oscillators in
spin-electronics [9-14]. Scaling of colloidal patterning down to 10-nm and
below, dimensions comparable or smaller than the main relaxation lengths in the
relevant materials, including metals, is expected to enable a variety of new
ballistic transport and photonic devices, such as spin-flip THz lasers [15]. In
this work we extend the practice of colloidal lithography to producing
large-area, near-ballistic-injection, sub-10 nm point-contact arrays and
demonstrate their integration in to spin-photo-electronic devices.Comment: 15 pages, 5 figure
Applicazione di tecniche fotogrammetriche per il progetto di restauro dell\u2019Istituto Agrario \u201cCastelnuovo\u201d a Palermo
Il lavoro illustra le fasi di realizzazione del rilevamento architettonico dell\u2019Istituto Agrario Castelnuovo di Palermo. Le operazioni di rilevamento sono state eseguite quale supporto al progetto di restauro. L\u2019area di pertinenza dell\u2019Istituto \ue8 costituita da vari edifici a diversa destinazione d\u2019uso e da un esteso parco. Oggetto di questo studio \ue8 l\u2019edificio principale del Ginnasio, realizzato dall\u2019architetto Antonino Gentile nella prima met\ue0 del XIX secolo. Per il rilevamento sono state utilizzate tecniche di tipo topografico e fotogrammetrico digitale che hanno consentito di eseguire la restituzione tridimensionale ed i fotopiani relativi ai prospetti esterni. Entrambi gli elaborati sono stati utilizzati per la realizzazione del modello tridimensionale fotorealistico dell\u2019edificio
Distinct subpopulations of enteric neuronal progenitors defined by time of development, sympathoadrenal lineage markers and Mash-1-dependence
Enteric and sympathetic neurons have previously been proposed to be lineally related. We present independent lines of evidence that suggest that enteric neurons arise from at least two lineages, only one of which expresses markers in common with sympathoadrenal cells. In the rat, sympathoadrenal markers are expressed, in the same order as in sympathetic neurons, by a subset of enteric neuronal precursors, which also transiently express tyrosine hydroxylase. If this precursor pool is eliminated in vitro by complement-mediated lysis, enteric neurons continue to develop; however, none of these are serotonergic. In the mouse, the Mash-1−/− mutation, which eliminates sympathetic neurons, also prevents the development of enteric serotonergic neurons. Other enteric neuronal populations, however, including those that contain calcitonin gene related peptide are present. Enteric tyrosine hydroxylase-containing cells co-express Mash-1 and are eliminated by the Mash-1−/− mutation, consistent with the idea that in the mouse, as in the rat, these precursors generate serotonergic neurons. Serotonergic neurons are generated early in development, while calcitonin gene related peptide-containing enteric neurons are generated much later. These data suggest that enteric neurons are derived from at least two progenitor lineages. One transiently expresses sympathoadrenal markers, is Mash-1-dependent, and generates early-born enteric neurons, some of which are serotonergic. The other is Mash-1-independent, does not express sympathoadrenal markers, and generates late-born enteric neurons, some of which contain calcitonin gene related peptide
Entanglement Dynamics of Two Independent Cavity-Embedded Quantum Dots
We investigate the dynamical behavior of entanglement in a system made by two
solid-state emitters, as two quantum dots, embedded in two separated
micro-cavities. In these solid-state systems, in addition to the coupling with
the cavity mode, the emitter is coupled to a continuum of leaky modes providing
additional losses and it is also subject to a phonon-induced pure dephasing
mechanism. We model this physical configuration as a multipartite system
composed by two independent parts each containing a qubit embedded in a
single-mode cavity, exposed to cavity losses, spontaneous emission and pure
dephasing. We study the time evolution of entanglement of this multipartite
open system finally applying this theoretical framework to the case of
currently available solid-state quantum dots in micro-cavities.Comment: 10 pages, 4 figures, to appear in Topical Issue of Physica Scripta on
proceedings of CEWQO 201
Vacancy decay in endohedral atoms: the role of non-central position of the atom
We demonstrate that the Auger decay rate in an endohedral atom is very
sensitive to the atom's location in the fullerene cage. Two additional decay
channels appear in an endohedral system: (a) the channel due to the change in
the electric field at the atom caused by dynamic polarization of the fullerene
electron shell by the Coulomb field of the vacancy, (b) the channel within
which the released energy is transferred to the fullerene electron via the
Coulomb interaction. % The relative magnitudes of the correction terms are
dependent not only on the position of the doped atom but also on the transition
energy \om. Additional enhancement of the decay rate appears for transitions
whose energies are in the vicinity of the fullerene surface plasmons energies
of high multipolarity. % It is demonstrated that in many cases the additional
channels can dominate over the direct Auger decay resulting in pronounced
broadening of the atomic emission lines. % The case study, carried out for
Sc@C, shows that narrow autoionizing resonances in an
isolated Sc within the range \om = 30... 45 eV are dramatically
broadened if the ion is located strongly off-the-center. % Using the developed
model we carry out quantitative analysis of the photoionization spectrum for
the endohedral complex ScN@C and demonstrate that the additional
channels are partly responsible for the strong modification of the
photoionization spectrum profile detected experimentally by
M\"{u}ller et al. (J. Phys.: Conf. Ser. 88, 012038 (2008)).Comment: 32 pages, 11 figure
Short term wind speed prediction using Multi Layer Perceptron
Among renewable energy sources wind energy is having an increasing influence on the supply of energy power. However wind energy is not a stationary power, depending on the fluctuations of the wind, so that is necessary to cope with these fluctuations that may cause problems the electricity grid stability. The ability to predict short-term wind speed and consequent production patterns becomes critical for the all the operators of wind energy.
This paper studies several configurations of Artificial Neural Networks (ANN), a well-known
tool able to estimate wind speed starting from measured data. The presented ANNs, t have
been tested through data gathered in the area of Trapani (Sicily). Different models have been
studied in order to determine the best architecture, minimizing statistical error. Simulation results show that the estimated values of wind speed are in good accord with the values measured by the anemometers
Experimental demonstration of phase-remapping attack in a practical quantum key distribution system
Unconditional security proofs of various quantum key distribution (QKD)
protocols are built on idealized assumptions. One key assumption is: the sender
(Alice) can prepare the required quantum states without errors. However, such
an assumption may be violated in a practical QKD system. In this paper, we
experimentally demonstrate a technically feasible "intercept-and-resend" attack
that exploits such a security loophole in a commercial "plug & play" QKD
system. The resulting quantum bit error rate is 19.7%, which is below the
proven secure bound of 20.0% for the BB84 protocol. The attack we utilize is
the phase-remapping attack (C.-H. F. Fung, et al., Phys. Rev. A, 75, 32314,
2007) proposed by our group.Comment: 16 pages, 6 figure
Using patterns position distribution for software failure detection
Pattern-based software failure detection is an important topic of research in recent years. In this method, a set of patterns from program execution traces are extracted, and represented as features, while their occurrence frequencies are treated as the corresponding feature values. But this conventional method has its limitation due to ignore the pattern’s position information, which is important for the classification of program traces. Patterns occurs in the different positions of the trace are likely to represent different meanings. In this paper, we present a novel approach for using pattern’s position distribution as features to detect software failure. The comparative experiments in both artificial and real datasets show the effectiveness of this method
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