Qubit-portraits of qudit states and quantum correlations

The machinery of qubit-portraits of qudit states, recently presented, is consider here in more details in order to characterize the presence of quantum correlations in bipartite qudit states. In the tomographic representation of quantum mechanics, Bell-like inequalities are interpreted as peculiar properties of a family of classical joint probability distributions which describe the quantum state of two qudits. By means of the qubit-portraits machinery a semigroup of stochastic matrices can be associated to a given quantum state. The violation of the CHSH inequalities is discussed in this framework with some examples, we found that quantum correlations in qutrit isotropic states can be detected by the suggested method while it cannot in the case of qutrit Werner states.Comment: 12 pages, 4 figure

Forgetfulness of continuous Markovian quantum channels

The notion of forgetfulness, used in discrete quantum memory channels, is slightly weakened in order to be applied to the case of continuous channels. This is done in the context of quantum memory channels with Markovian noise. As a case study, we apply the notion of weak-forgetfulness to a bosonic memory channel with additive noise. A suitable encoding and decoding unitary transformation allows us to unravel the effects of the memory, hence the channel capacities can be computed using known results from the memoryless setting.Comment: 6 pages, 2 figures, comments are welcome. Minor corrections and acknoledgment adde

Ageostrophic Forcing in a Height Tendency Equation

The role of the ageostrophic vorticity tendencies in the Zwack-Okossi vorticity tendency equation has been examined within the context that this term in the equation acts as a correction term for the vorticity tendency or height tendency calculations. In this paper, this term is shown to act as both a response to initial forcing and as a forcing mechanism itself in modulating the initial forcing. Using an earlier methodology for partitioning the wind field and the height field into their divergent and rotational parts, the ageostrophic wind is shown to contain components of both parts. Then, using an omega equation, an ageostrophic vorticity tendency is calculated, which has forcing mechanisms similar to a height tendency equation. This ageostrophic tendency is then used in this height tendency equation and provides for an improved method of calculating the ageostrophic wind rather than simply calculating it as a residual. Two case studies are then examined to demonstrate this point. For both case studies, the calculated height tendencies using the derived ageostrophic winds and those calculated as a residual overestimated the height tendencies, especially at the surface. While the correlation coefficients show that the two methods are comparable at 500 hPa, at the surface there is a notable degree of improvement in the pattern similarity. This resulted in an improved representation of the 500-hPa height tendencies for the onset of the Atlantic blocking event despite marginal improvements in the calculated field overall

Synoptic/planetary-scale interactions and blocking over the North Atlantic Ocean

The central theme of this project has been the diagnosis of blocking anticyclogenesis and the corresponding interactions with synoptic-scale circulations. To that end an extensive investigation of the dynamics and energetics of a major blocking anticyclone and two upstream cyclones, all of which occurred over the North Atlantic Ocean and the United States in January 1979, was undertaken. Data for the study were provided by Goddard Laboratory for Atmospheres (GLA) 4 LAT by 5 LON FGGE analyses. The methodology has primarily focused on the diagnosis of circulation forcing mechanisms using the modified forms (referred to as the extended forms) of the height tendency and Zwack-Okossi equations developed by our research group. Calculations use routine second-order finite differencing with boundary layer fraction and sensible heating and latent heat release represented as parameterized quantities. Of particular interest are the latent heat release estimates, which combine convectional parameterized values with estimates derived from satellite IR data. The latter were obtained using an algorithm derived by Dr. Franklin R. Robertson of NASA's Marshall Space Flight Center. Results are contained in project reports, theses and publications identified in previous review summaries and reports, and publications listed at the end of this summary. Significant accomplishments in the past year are presented

A Diagnosis of Two Blocking Events That Occurred Simultaneously in the Midlatitude Northern Hemisphere

Using the Goddard Laboratory for Atmospheres Goddard Earth Observing System-1 analyses, the horizontal distribution of atmospheric forcing processes involved in the growth, maintenance, and decay of two Northern Hemisphere midlatitude blocking anticyclones that occurred simultaneously were examined, with the goal of determining whether there was a dynamic connection between the two cases. The complete form of the Zwack- Okossi equation, which is a generalization of the Petterssen-Sutcliffe development equation, was used as the primary diagnostic tool. The basic analyses were partitioned into their planetary-scale and synoptic-scale components (noninteraction) 500-hPa height tendencies, as well as scale interaction 500-hPa height tendencies. Based on the results of this diagnosis, there was no dynamic connection between these blocking anticyclones. This result agrees with findings of other studies based on a statistical analysis of simultaneous blocking. These results also imply that blocking may be a local phenomenon. The diagnostic results from these blocking events were, in many respects, similar to those of previous studies. However, some key differences were found. For example, it was found here that for both mode 2 blocking events, temperature advection was an important mechanism in block formation. Earlier results showed vorticity advection as the primary atmospheric forcing process in block formation for a mode 1 block. Also, the scalepartitioned results show that upstream cyclones contributed to block formation and intensification in these events directly through the synoptic-scale component, often with the support of the interaction component, of the total forcing. Earlier scale-partitioned results showed that the interaction component of the total forcing was most important in the formation of a mode 1 block

Dorsoventral patterning of the Xenopus eye involves differential temporal changes in the response of optic stalk and retinal progenitors to Hh signalling

Background: Hedgehog (Hh) signals are instrumental to the dorsoventral patterning of the vertebrate eye, promoting optic stalk and ventral retinal fates and repressing dorsal retinal identity. There has been limited analysis, however, of the critical window during which Hh molecules control eye polarity and of the temporal changes in the responsiveness of eye cells to these signals. Results: In this study, we used pharmacological and molecular tools to perform stage-specific manipulations of Hh signalling in the developing Xenopus eye. In gain-of-function experiments, most of the eye was sensitive to ventralization when the Hh pathway was activated starting from gastrula/neurula stages. During optic vesicle stages, the dorsal eye became resistant to Hh-dependent ventralization, but this pathway could partially upregulate optic stalk markers within the retina. In loss-of-function assays, inhibition of Hh signalling starting from neurula stages caused expansion of the dorsal retina at the expense of the ventral retina and the optic stalk, while the effects of Hh inhibition during optic vesicle stages were limited to the reduction of optic stalk size. Conclusions: Our results suggest the existence of two competence windows during which the Hh pathway differentially controls patterning of the eye region. In the first window, between the neural plate and the optic vesicle stages, Hh signalling exerts a global influence on eye dorsoventral polarity, contributing to the specification of optic stalk, ventral retina and dorsal retinal domains. In the second window, between optic vesicle and optic cup stages, this pathway plays a more limited role in the maintenance of the optic stalk domain. We speculate that this temporal regulation is important to coordinate dorsoventral patterning with morphogenesis and differentiation processes during eye development

Social Media Marketing Adoption Strategies: An Exploratory Multiple Case Study of Landscape Industry Small Businesses

Despite research contending that marketing is a pivotal factor in small business success, many small business owners continue to underutilize low-cost marketing options available to them. Of these options, social media marketing is a useful tool to maintain competitiveness in the larger marketplace. However, the adoption of social media best practices in small business remains deficient. The landscape industry is a large and growing field with small businesses making up a large and growing share of the industry. Yet some landscape industry small business owners lack strategies to adopt innovative social media marketing strategies to help ensure business viability. This study incorporated a qualitative, exploratory multiple-case study design to explore how landscape industry small business owners use social media marketing strategies to help ensure business viability. Results indicated that successful marketing strategies tended to incorporate Facebook as the primary social media tool and included content such as service, education, and holiday posts. Benefits of social media marketing primarily centered on low-cost marketing options for improved visibility, while challenges included a trial-and-error learning curve. Results of this study might help small businesses improve their long-term viability through social media marketing strategies

Memory effects in attenuation and amplification quantum processes

With increasing communication rates via quantum channels, memory effects become unavoidable whenever the use rate of the channel is comparable to the typical relaxation time of the channel environment. We introduce a model of a bosonic memory channel, describing correlated noise effects in quantum-optical processes via attenuating or amplifying media. To study such a channel model, we make use of a proper set of collective field variables, which allows us to unravel the memory effects, mapping the n-fold concatenation of the memory channel to a unitarily equivalent, direct product of n single-mode bosonic channels. We hence estimate the channel capacities by relying on known results for the memoryless setting. Our findings show that the model is characterized by two different regimes, in which the cross correlations induced by the noise among different channel uses are either exponentially enhanced or exponentially reduced.Comment: 10 pages, 7 figures, close to the published versio