Electronic viscosity in a quantum well: A test for the local density approximation

In the local density approximation (LDA) for electronic time-dependent current-density functional theory (TDCDFT) many-body effects are described in terms of the visco-elastic constants of the homogeneous three-dimensional electron gas. In this paper we critically examine the applicability of the three-dimensional LDA to the calculation of the viscous damping of 1-dimensional collective oscillations of angular frequency $\omega$ in a quasi 2-dimensional quantum well. We calculate the effective viscosity $\zeta(\omega)$ from perturbation theory in the screened Coulomb interaction and compare it with the commonly used three-dimensional LDA viscosity $Y(\omega)$. Significant differences are found. At low frequency $Y(\omega)$ is dominated by a shear term, which is absent in $\zeta(\omega)$. At high frequency $\zeta(\omega)$ and $Y(\omega)$ exhibit different power law behaviors ($\omega^{-3}$ and $\omega^{-5/2}$ respectively), reflecting different spectral densities of electron-hole excitations in two and three dimensions. These findings demonstrate the need for better approximations for the exchange-correlation stress tensor in specific systems where the use of the three-dimensional functionals may lead to unphysical results.Comment: 10 pages, 7 figures, RevTex

Intersemiotic transcreation: the life and afterlife of Giuseppe Verdi's Macbeth.

Macbeth was a nobleman, a king, a supporter of Christianity in Scotland, but most of all he was, and still is, the protagonist of countless adventures, told through music, singing, verse, prose, fiction, film. And translated into an infinite array of languages. The stories of Macbeth, all together and seen one at a time, embody the very essence of translation, in creative ways. This essay sets forth the notion of intersemiotic transcreation precisely with reference to the story of Macbeth, by reconstructing its evolution and by focusing especially on Giuseppe Verdi\u2019s worldwide famous opera named after the Scottish king. A detailed analysis is also offered of two contemporary English versions of Giuseppe Verdi\u2019s Macbeth, in an attempt to understand where translation finishes, if it does, and where intersemiotic transcreation starts. Both types of translation examined (interlingual surtitles and singing translation) recall processes of transmutation, change, (re)creation and transcreation, and bear witness to the creativity which goes hand in hand with writing and translating, over the centuries and across codes of communication

Photonic circuits for generating modal, spectral, and polarization entanglement

We consider the design of photonic circuits that make use of Ti:LiNbO$_{3}$ diffused channel waveguides for generating photons with various combinations of modal, spectral, and polarization entanglement. Down-converted photon pairs are generated via spontaneous optical parametric down-conversion (SPDC) in a two-mode waveguide. We study a class of photonic circuits comprising: 1) a nonlinear periodically poled two-mode waveguide structure, 2) a set of single-mode and two-mode waveguide-based couplers arranged in such a way that they suitably separate the three photons comprising the SPDC process, and, for some applications, 3) a holographic Bragg grating that acts as a dichroic reflector. The first circuit produces frequency-degenerate down-converted photons, each with even spatial parity, in two separate single-mode waveguides. Changing the parameters of the elements allows this same circuit to produce two nondegenerate down-converted photons that are entangled in frequency or simultaneously entangled in frequency and polarization. The second photonic circuit is designed to produce modal entanglement by distinguishing the photons on the basis of their frequencies. A modified version of this circuit can be used to generate photons that are doubly entangled in mode number and polarization. The third photonic circuit is designed to manage dispersion by converting modal, spectral, and polarization entanglement into path entanglement

Coliseum : March or Two Step

https://digitalcommons.library.umaine.edu/mmb-ps/3092/thumbnail.jp

Viscous corrections to the resistance of nano-junctions: a dispersion relation approach

It is well known that the viscosity of a homogeneous electron liquid diverges in the limits of zero frequency and zero temperature. A nanojunction breaks translational invariance and necessarily cuts off this divergence. However, the estimate of the ensuing viscosity is far from trivial. Here, we propose an approach based on a Kramers-Kr\"onig dispersion relation, which connects the zero-frequency viscosity, $\eta(0)$, to the high-frequency shear modulus, $\mu_{\infty}$, of the electron liquid via $\eta(0) =\mu_{\infty} \tau$, with $\tau$ the junction-specific momentum relaxation time. By making use of a simple formula derived from time-dependent current-density functional theory we then estimate the many-body contributions to the resistance for an integrable junction potential and find that these viscous effects may be much larger than previously suggested for junctions of low conductance.Comment: 6 pages, 5 figures, Revised versio

Paediatric ambulatory care sensitive hospitalisation and Italian deprivation index. Retrospective multilevel analysis of administrative data from 2008 to 2018 in the Abruzzo Region (Southern Italy)

OBJECTIVES: to estimate and analyse the trend of paediatric hospitalisations for Ambulatory Care Sensitive Conditions (ACSCs) from 2008 to 2018 in a region of southern Italy and to assess the association with the socio-economic deprivation index (DI). DESIGN: retrospective observational study. SETTING AND PARTICIPANTS: ACSC hospitalisations in children (<=18 years) were identified. Discharges for ACSC of the Abruzzo Region from 2008 to 2018 were selected and the deprivation index of the municipality of residence was assigned to the hospital discharge record where the patient's residence was reported. MAIN OUTCOME MEASURES: the rate of paediatric preventable admissions (PPHs) related to ACSC, standardized by age and gender with the direct method, was calculated for the years of observation. The average annual percentage change (AAPC) was calculated with a trend analysis. In addition, the odds ratios (ORs) of hospitalisation for ACSC were calculated using a hierarchical logistic regression model. RESULTS: 252,513 hospitalisations were examined, of which 16,264 (6.4%) attributable to ACSC. During the study period, the hospitalisation rate decreased from 8.59 per 1,000 to 6.12 per 1,000 residents, with an AAPC of -3.7, which was statistically significant (p<0.05). Furthermore, an association was highlighted between hospitalisations related to ACSC and the deprivation of the municipality of residence. Using as a comparison people residing in the municipalities belonging to the first quintile, the least deprived, the strength of the association between PPHs and DI increased from the third quintile (OR 1.13; CI95% 1.02-1.24) up to the fifth quintile, most deprived (OR 1.14; CI95% 1.01-1.30). CONCLUSIONS: paediatric patients residing in Abruzzo have a risk of undergoing a preventable hospitalisation associated with an ACSC which depends on the deprivation index of the municipality of residence. Although it is difficult to evaluate the mechanisms involved in the relationship between economic deprivation and hospitalisation, DI can be useful to identify the areas which are most at risk on which to prioritize public health interventions

Trend in primary caesarean delivery. A five-year experience in Abruzzo, Italy

Background: Primary caesarean section (PCS) rate is one of the main indicators of quality of care suggested by the Italian Government. Hospital rankings are usually based on it, therefore lower rates reflect more appropriate clinical practice. The aim of this study is to describe a five-year trend of PCS rate in Abruzzo region from 2009 to 2013 and to examine the medical indications for this mode of delivery. Methods: Forty-five thousand one hundred forty-nine deliveries occurring from 2009 to 2013 were collected from all hospital discharge records (HDR) and analyzed. Among them we found 12,542 PCS. Odds ratios (ORs) with 95% confidence interval (95% CI) were estimated using logistic regression methods to evaluate the relationship between maternal risk factors and PCS in hospital over 1000 delivery/yrs. Results: The five-year PCS rate was 28.9%, with a decreasing trend from 31.4% in 2009 to 26.1% in 2013. Vasto Civil Hospital shows the lowest PCS rate (17.9% in 2013) among hospitals with a maximum of 1000 deliveries per year, while Pescara Civil Hospital shows the lowest PCS rate (25.4% in 2013) among hospitals with over 1000 deliveries per year. Women with major risk factors for cesarean section delivered more frequently in maternity units over 1000 delivery/yrs. Logistic regression analyses showed as diabetes, hypertension, twin pregnancy, fetal distress and preterm delivery were significant risk factors to deliver in unit over 1000 delivery/yrs. The most frequent (overall 66.6%) discharge diagnosis recorded in Hospital discharge records (HDR) is "Caesarean Delivery Without Indication". 7.3% of PCS made in Abruzzo concerns women living in other Italian regions. 11.4% of PCS contains one of the indications to caesarean section (CS) that the Italian Guidelines consider appropriate. Conclusions: During the analyzed period, Abruzzo showed a decreasing, but still too high, PCS rate, compared to the limits fixed by the Italian Ministry of Health. Considering the limitation of this study, based on administrative data that are poor in clinical information, it is not possible to define the appropriateness of all caesarean sections

Families of Proper Holomorphic Embeddings and Carleman-type Theorems with parameters

We solve the problem of simultaneously embedding properly holomorphically into $\Bbb C^2$ a whole family of $n$-connected domains $\Omega_r\subset\Bbb P^1$ such that none of the components of $\Bbb P^1\setminus\Omega_r$ reduces to a point, by constructing a continuous mapping $\Xi\colon\bigcup_r\{r\}\times\Omega_r\to\Bbb C^2$ such that $\Xi(r,\cdot)\colon\Omega_r\hookrightarrow\Bbb C^2$ is a proper holomorphic embedding for every $r$. To this aim, a parametric version of both the Anders\'en-Lempert procedure and Carleman's Theorem is formulated and proved

Time dependent Markovian master equation beyond the adiabatic limit

We develop a Markovian master equation that models the evolution of systems subject to arbitrary driving and control fields. Our approach combines time rescaling and weak-coupling limits for the system-environment interaction with a secular approximation. The derivation makes use of the adiabatic time evolution operator in a manner that allows for the efficient description of strong driving, while recovering the adiabatic master equation in the appropriate limit. To illustrate the effectiveness of our approach, we apply it to the paradigmatic case of a two-level (qubit) system subjected to a form of periodic driving that remains unsolvable using a Floquet representation. We demonstrate the reliability and broad scope of our approach by benchmarking the solutions of the derived reduced time evolution against numerically exact simulations using tensor networks. Our results provide rigorous conditions that must be satisfied by phenomenological master equations for driven systems that do not rely on first principles derivations.Comment: 20+8 pages, 5 figures. Comments are welcom