Quantum Criticality in a Bosonic Josephson Junction

In this paper we consider a bosonic Josephson junction described by a two-mode Bose-Hubbard model, and we thoroughly analyze a quantum phase transition occurring in the system in the limit of infinite bosonic population. We discuss the relation between this quantum phase transition and the dynamical bifurcation occurring in the spectrum of the Discrete Self Trapping equations describing the system at the semiclassical level. In particular, we identify five regimes depending on the strength of the effective interaction among bosons, and study the finite-size effects arising from the finiteness of the bosonic population. We devote a special attention to the critical regime which reduces to the dynamical bifurcation point in the thermodynamic limit of infinite bosonic population. Specifically, we highlight an anomalous scaling in the population imbalance between the two wells of the trapping potential, as well as in two quantities borrowed from Quantum Information Theory, i.e. the entropy of entanglement and the ground-state fidelity. Our analysis is not limited to the zero temperature case, but considers thermal effects as well.Comment: 13 pages, 10 figure

New linearization and reweighting for simulations of string sigma-model on the lattice

We study the discretized worldsheet of Type IIB strings in the Gubser-Klebanov-Polyakov background in a new setup, which eliminates a complex phase previously detected in the fermionic determinant. A sign ambiguity remains, which a study of the fermionic spectrum shows to be related to Yukawa-like terms, including those present in the original Lagrangian before the linearization standard in a lattice QFT approach. Monte Carlo simulations are performed in a large region of the parameter space, where the sign problem starts becoming severe and instabilities appear due to the zero eigenvalues of the fermionic operator. To face these problems, simulations are conducted using the absolute value of a fermionic Pfaffian obtained introducing a small twisted-mass term, acting as an infrared regulator, into the action. The sign of the Pfaffian and the low modes of the quadratic fermionic operator are then taken into account by a reweighting procedure of which we discuss the impact on the measurement of the observables. In this setup we study bosonic and fermionic correlators and observe a divergence in the latter, which we argue - also via a one-loop analysis in lattice perturbation theory - to originate from the U(1)-breaking of our Wilson-like discretization for the fermionic sector

RUMORES DE UMA VIDA

Tece-se essa pesquisa na interface entre modos de vida no contemporâneo e literatura.Como meio de produção de uma escrita, este trabalho faz-se via fragmentos literários.Como problema, delineia-se: escrever em meio a corpos cansados que se arrastam sob a égide do niilismo reativo no contemporâneo, na tênue linha de não encampar uma denúncia, mas perseguir uma estética, um modo de expressão do que se passa. Buscouse,para isso, uma estética trágica. Com o intuito de tomar o trágico como ação, como afirmação estética e filosófica para urdir uma vida, indo de encontro às amarras do niilismo. Desse modo, moveu a urdidura desses fragmentos-dissertativos: como disparar linhas que possibilitem afirmar novas suavidades em corpos conformados? A Literatura,inacabada, informe, pode operar na produção de estranhamentos de corpos esgarçados, como encontro com a alteridade; afirma-se a literatura menor como linha revolucionária. Como metodologia, fragmentos literários foram produzidos e compartilhados com a pergunta: você quer participar de uma experiência literária? Assim, cada fragmento encontra-se nesse trabalho acompanhado do respectivo retorno daqueles que aceitaram o convite. Todos os fragmentos tocam em vidas cansadas, em corpos fatigados. Escrever é entrar em contato com um dispositivo que pode fazê-los outros, deslocá-los. Palavras-chave: cansaço; contemporâneo; literatura menor; fragmentos

Histopathological determinants of autofluorescence patterns in oral carcinoma

Biological tissues (including oral mucosa) can absorb and re-emit specific light wavelengths, detectable through spectrophotometric devices. Such a phenomenon is known as \u201cautofluorescence\u201d (AF). Several devices evaluating tissue AF have been developed and commercialized in the last two decades. Among these, the VELscope\uae system has been proposed as a visual diagnostic aid for potentially malignant disorders and malignant lesions of the oral mucosa. In the present pilot study, we investigated which are the main histopathological features possibly related to variations in AF patterns in a set of 20 oral squamous cell verrucous carcinoma. Among all the histological features investigated, only the mean width of keratin was significantly different between hypofluorescent and hyperfluorescent carcinomas. The results of the present study demonstrate that AF features of oral malignant lesions are significantly associated with the width of their keratin layer

Photobiomodulation with a 645 nm Diode Laser of Saos-2 Cells and Platelet-Rich Plasma: The Potential for a New Mechanism of Action

Objective: The main focus of this in vitro study was to highlight possible differences between outcomes of photobiomodulation performed in the presence or absence of growth factors derived from platelet-rich plasma.Background: Photobiomodulation has garnered increasing attention, thanks to a large number of controlled clinical trials that have proven its efficacy in various oral pathologies. Nevertheless, the mechanism of action is still a matter of debate.Materials and methods: The cell model used was Saos-2ATTC HTB-85, a human osteosarcoma cell line that retains an osteogenic potential matching that of osteoblastic cells. Photobiomodulation was performed with a 645 nm diode laser; we investigated three different fluence values (2, 5, and 10 J/cm(2)) delivered with 3 different irradiation times (1, 2, and 4 min). The design of the study included a case-control structure. Cell viability was assessed by resazurin reduction assay before laser irradiation. We assessed cell differentiation by Alizarin-red Sigma Aldrich assay 48 h after the last laser irradiation.Results: Results show that the combination of photobiomodulation and platelet-rich plasma can lead to a statistically significant increase in both proliferation and differentiation rates.Conclusions: Only a defined amount of energy, that is, a fluence of 5 J/cm(2) delivered in 2 min and of 10 J/cm(2) in 4 min, was proven to be the most effective in the presence of platelet-rich plasma to induce cell proliferation and calcium deposition

Strings on the lattice and AdS/CFT

We present a new auxiliary field representation for the four-fermi term of the gauge-fixed Green-Schwarz superstring action which describes fluctuations around the null-cusp background in $AdS_5\times S^5$. We sketch the main features of the fermionic operator spectrum, identifying the region of parameter space where the sign ambiguity is absent. Measurements for the observables in the setup here described are presented and discussed in a forthcoming publication

On the Origin of the Early Solar System Radioactivities. Problems with the AGB and Massive Star Scenarios

Recent improvements in stellar models for intermediate-mass and massive stars are recalled, together with their expectations for the synthesis of radioactive nuclei of lifetime $\tau \lesssim 25$ Myr, in order to re-examine the origins of now extinct radioactivities, which were alive in the solar nebula. The Galactic inheritance broadly explains most of them, especially if $r$-process nuclei are produced by neutron star merging according to recent models. Instead, $^{26}$Al, $^{41}$Ca, $^{135}$Cs and possibly $^{60}$Fe require nucleosynthesis events close to the solar formation. We outline the persisting difficulties to account for these nuclei by Intermediate Mass Stars (2 $\lesssim$ M/M$_\odot \lesssim 7 - 8$). Models of their final stages now predict the ubiquitous formation of a $^{13}$C reservoir as a neutron capture source; hence, even in presence of $^{26}$Al production from Deep Mixing or Hot Bottom Burning, the ratio $^{26}$Al/$^{107}$Pd remains incompatible with measured data, with a large excess in $^{107}$Pd. This is shown for two recent approaches to Deep Mixing. Even a late contamination by a Massive Star meets problems. In fact, inhomogeneous addition of Supernova debris predicts non-measured excesses on stable isotopes. Revisions invoking specific low-mass supernovae and/or the sequential contamination of the pre-solar molecular cloud might be affected by similar problems, although our conclusions here are weakened by our schematic approach to the addition of SN ejecta. The limited parameter space remaining to be explored for solving this puzzle is discussed.Comment: Accepted for publication on Ap

Large-sized pleomorphic adenoma of the cheek treated with Nd:Yag laser: Report of a case and review of the literature

Pleomorphic adenoma (PA) mostly involves parotid glands, while extra-parotid localizations are relatively uncommon. Particularly, PAs of the cheek minor salivary glands with a size larger than 4 cm are exceedingly rare, with only few cases reported. Surgical treatment of PA usually consists in radical excision. However, despite a presumptive radicality, recurrences, sometimes followed by malignant transformation, may occur. Here we report a case of a large-sized (6 cm) PA of the cheek minor salivary glands in a 70 year-old female patient, successfully treated through a conservative approach, based on the use of Nd:YAG Laser (λ=1064 nm). No recurrences were observed after a 2-year follow-up. A concise review of the literature, describing the features of 14 cases is also provided. Advantages of laser treatment include a precise cut, reduction of trauma on surrounding tissues, the possibility of a very good intraoperative hemostasis. Such features may sometimes allow to avoid general anesthesia, even for removal of big lesions. Post-operative course, in terms of pain and swelling, is usually better for intervention performed with laser, when compared to traditional surgery