Design of an RSFQ Control Circuit to Observe MQC on an rf-SQUID

We believe that the best chance to observe macroscopic quantum coherence (MQC) in a rf-SQUID qubit is to use on-chip RSFQ digital circuits for preparing, evolving and reading out the qubit's quantum state. This approach allows experiments to be conducted on a very short time scale (sub-nanosecond) without the use of large bandwidth control lines that would couple environmental degrees of freedom to the qubit thus contributing to its decoherence. In this paper we present our design of a RSFQ digital control circuit for demonstrating MQC in a rf-SQUID. We assess some of the key practical issues in the circuit design including the achievement of the necessary flux bias stability. We present an "active" isolation structure to be used to increase coherence times. The structure decouples the SQUID from external degrees of freedom, and then couples it to the output measurement circuitry when required, all under the active control of RSFQ circuits. Research supported in part by ARO grant # DAAG55-98-1-0367.Comment: 4 pages. More information and publications at http://www.ece.rochester.edu:8080/users/sde/research/publications/index.htm

Instability statistics and mixing rates

We claim that looking at probability distributions of \emph{finite time} largest Lyapunov exponents, and more precisely studying their large deviation properties, yields an extremely powerful technique to get quantitative estimates of polynomial decay rates of time correlations and Poincar\'e recurrences in the -quite delicate- case of dynamical systems with weak chaotic properties.Comment: 5 pages, 5 figure

Transcriptional regulatory networks controlling woolliness in peach in response to preharvest gibberellin application and cold storage

BACKGROUND: Postharvest fruit conservation relies on low temperatures and manipulations of hormone metabolism to maintain sensory properties. Peaches are susceptible to chilling injuries, such as ‘woolliness’ that is caused by juice loss leading to a ‘wooly’ fruit texture. Application of gibberellic acid at the initial stages of pit hardening impairs woolliness incidence, however the mechanisms controlling the response remain unknown. We have employed genome wide transcriptional profiling to investigate the effects of gibberellic acid application and cold storage on harvested peaches. RESULTS: Approximately half of the investigated genes exhibited significant differential expression in response to the treatments. Cellular and developmental process gene ontologies were overrepresented among the differentially regulated genes, whereas sequences in cell death and immune response categories were underrepresented. Gene set enrichment demonstrated a predominant role of cold storage in repressing the transcription of genes associated to cell wall metabolism. In contrast, genes involved in hormone responses exhibited a more complex transcriptional response, indicating an extensive network of crosstalk between hormone signaling and low temperatures. Time course transcriptional analyses demonstrate the large contribution of gene expression regulation on the biochemical changes leading to woolliness in peach. CONCLUSION: Overall, our results provide insights on the mechanisms controlling the complex phenotypes associated to postharvest textural changes in peach and suggest that hormone mediated reprogramming previous to pit hardening affects the onset of chilling injuries. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12870-015-0659-2) contains supplementary material, which is available to authorized users

Analytical results for a Bessel function times Legendre polynomials class integrals

When treating problems of vector diffraction in electromagnetic theory, the evaluation of the integral involving Bessel and associated Legendre functions is necessary. Here we present the analytical result for this integral that will make unnecessary numerical quadrature techniques or localized approximations. The solution is presented using the properties of the Bessel and associated Legendre functions.Comment: 4 page

Influencia del tiempo de gelificación sobre las propiedades estructurales, vibracionales y eléctricas del compósito PEG0.2/V2O5

Se estudiaron las propiedades estructurales, vibracionales y eléctricas de películas V2O5·nH2O y PEG0.2/V2O5 en función del tiempo de gelificación. Las películas fueron sinterizadas por sol-gel mediante la ruta del pentóxido de vanadio sobre sustratos de vidrio previamente tratados. La caracterización se llevo a cabo mediante Difracción de Rayos-X, Espectroscopía Raman y el método de las cuatro puntas convencional de van der Pauw. Los resultados indican que el aumento en el tiempo de gelificación del sol precursor (V2O5.nH2O) incrementa la calidad cristalina, el grado de hidratación, y la concentración de iones V5+ en las películas. En el compósito híbrido (PEG0.2/V2O5) los iones VO2+ actúan como enlazantes entre las cadenas poliméricas haciéndolas más compactas, lo cual facilita la movilidad de los portadores de carga eléctrica entre los iones vanadios. Los resultados mostraron una transición de fase semiconductormetal alrededor de 34°C, una transición óptica del tipo indirecta (para V2O5·nH2O) y una transición vítrea alrededor de Tg=-69°C.Structural, vibrational and electrical properties of V2O5·nH2O and PEG0.2/V2O5 films as a function of gelation time were studied. The films were sintered by sol-gel using vanadium pentoxide route on glass substrates previously treated. Films were characterized by X-Ray Diffraction, Raman Spectroscopy and the four-point van der Pauw conventional method. The results indicated that when the gelation time of the precursor (V2O5·nH2O) is increased, the crystalline quality, the degree of hydration, and V5+ ion concentration are increased. In the hybrid composite (PEG0.2/V2O5), VO2+ ions act as bonding between the polymer chains, making them more compact to facilitate the mobility of electric charge carriers between vanadium ions. The results showed a semiconductor-metal transition about 34°C, an indirect optical transition (V2O5·nH2O) and a vitreous transition around Tg=-69°C.Fil: Londoño Calderon, Cesar Leandro. Universidad Nacional de Colombia; Colombia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Jurado, J. F.. Universidad Nacional de Colombia; ColombiaFil: Vargas Hernández, C.. Universidad Nacional de Colombia; Colombi

To Each According to its Degree: The Meritocracy and Topocracy of Embedded Markets

A system is said to be meritocratic if the compensation and power available to individuals is determined by their abilities and merits. A system is topocratic if the compensation and power available to an individual is determined primarily by her position in a network. Here we introduce a model that is perfectly meritocratic for fully connected networks but that becomes topocratic for sparse networks-like the ones in society. In the model, individuals produce and sell content, but also distribute the content produced by others when they belong to the shortest path connecting a buyer and a seller. The production and distribution of content defines two channels of compensation: a meritocratic channel, where individuals are compensated for the content they produce, and a topocratic channel, where individual compensation is based on the number of shortest paths that go through them in the network. We solve the model analytically and show that the distribution of payoffs is meritocratic only if the average degree of the nodes is larger than a root of the total number of nodes. We conclude that, in the light of this model, the sparsity and structure of networks represents a fundamental constraint to the meritocracy of societies.MIT Media Lab Consortiu