Robust quantum boomerang effect in non-Hermitian systems

Anderson localization is a general phenomenon that applies to a variety of disordered physical systems. Recently, a novel manifestation of Anderson localization for wave packets launched with a finite average velocity was proposed, the Quantum boomerang effect (QBE). This phenomenon predicts that the disorder-averaged center of mass of a particle initially moves ballistically, then makes a U-turn, and finally slowly returns to its initial position. The QBE has been predicted to take place in several Hermitian models with Anderson localization and has been experimentally observed in the paradigmatic quantum kicked rotor model. In this work, we investigate the emergence of the QBE in non-Hermitian systems and clarify the importance of symmetries of the Hamiltonian and the initial state. We generalize the analytical arguments available in the literature and show that even in the case of complex spectrum a boomerang-like behavior can appear in a non-Hermitian system. We confirm our analytical results through a careful numerical investigation of the dynamics for several non-Hermitian models. We find that non-Hermiticity leads to the breakdown of the dynamical relation, though the QBE is preserved. This work opens up new avenues for future investigations in Anderson localized systems. The models studied here may be implemented using cold atoms in optical lattices.Comment: 14 pages, 10 figure

Steam - oxygen gasification of refuse derived fuel in fluidized beds: Modelling and pilot plant testing

A one-dimensional kinetic model for steam‑oxygen gasification of refuse derived fuel in a bubbling fluidized bed reactor has been developed. The model incorporates the reaction network of steam‑oxygen gasification within the fluid dynamics of a fluidized bed to predict waste and tars conversion, gas composition and overall gasification performance. The model was validated by comparing outlet products composition and temperature profile with experimental data from a pilot-scale fluidized bed gasifier, operated at different conditions. The model showed accurate predictive capability and ease of computation. The effects of the operating conditions on gas yield and process efficiency were evaluated and the most appropriate fuel feeding height, equivalent ratio and the relative amount of steam to inject were identified

Capgras-like syndrome in a patient with an acute urinary tract infection.

Delusional misidentification syndromes are a group of delusional phenomena in which patients misidentify familiar persons, objects, or themselves, believing that they have been replaced or transformed. In 25%-40% of cases, misidentification syndromes have been reported in association with organic illness. We report an acute episode of Capgras-like delusion lasting 8 days, focused on the idea that people were robots with human bodies, in association with an acute urinary infection. To our knowledge, this is the first case report associating urinary tract infection with Capgras-like syndrome. Awareness of the prevalence of delusional misidentification syndromes associated with acute medical illness should promote diligence on the part of clinicians in recognizing this disorder

Tunneling of polarized fermions in 3D double wells

We study the tunneling of a spin polarized Fermi gas in a three-dimensional double well potential, focusing on the time dynamics starting from an initial state in which there is an imbalance in the number of particles in the two wells. Although fermions in different doublets of the double well tunnel with different frequencies, we point out that (incoherent) oscillations of a large number of particles can arise, as a consequence of the presence of transverse degrees of freedom. Estimates of the doublet structure and of the occupation of transverse eigenstates for a realistic experimental setup are provided.Comment: 10 pages, Typos corrected and figures changed - published in Laser Physics, issue on the LPHYS'11 conference (Sarajevo, 2011

Abel-Jacobi maps for hypersurfaces and non commutative Calabi-Yau's

It is well known that the Fano scheme of lines on a cubic 4-fold is a symplectic variety. We generalize this fact by constructing a closed p-form with p=2n-4 on the Fano scheme of lines on a (2n-2)-dimensional hypersurface Y of degree n. We provide several definitions of this form - via the Abel-Jacobi map, via Hochschild homology, and via the linkage class, and compute it explicitly for n = 4. In the special case of a Pfaffian hypersurface Y we show that the Fano scheme is birational to a certain moduli space of sheaves on a p-dimensional Calabi--Yau variety X arising naturally in the context of homological projective duality, and that the constructed form is induced by the holomorphic volume form on X. This remains true for a general non Pfaffian hypersurface but the dual Calabi-Yau becomes non commutative.Comment: 34 pages; exposition of Hochschild homology expanded; references added; introduction re-written; some imrecisions, typos and the orbit diagram in the last section correcte

Ultrasonographic measurements of abdominal lymph nodes in growing puppies

The sonographic appearance of the normal abdominal lymph nodes in adult dogs has been well described, but the data in puppies are scarce and of poor quality. The aim of the current study was to evaluate any differences in abdominal lymph node sonographic measurements in puppies of various sizes and to determine whether any differences were correlated with growth and weight gain during the first 10 weeks of life. By an approach based on prospective and serial measurements, length, width and thickness of jejunal, medial iliac and hypogastric nodes were obtained in twenty-one healthy puppies of various sizes, at six (T0), eight (T1) and ten (T2) weeks of age. The relationship between body weight and length, width and thickness of lymph nodes was evaluated using a Pearson correlation analysis. An ANOVA test was used to compare the measurements at different ages. Jejunal and iliac lymph nodes were the largest in large breed dogs. In large-sized puppies only the length of the jejunal lymph nodes correlated positively with width and body weight. Length of medial iliac lymph nodes correlated positively with width and body weight in all three sizes. None of the measurements of hypogastric lymph nodes were related to body weight. In large-sized puppies jejunal and iliac lymph nodes increased in length and width with age; in medium-sized puppies only iliac lymph nodes increased; in small-sized puppies jejunal and iliac lymph nodes significantly decreased in length and thickness. In conclusion, the lymph node sizes in young animals are directly related to body weight and do not decrease with growth during the first 10 weeks of life, except in small-sized puppies

Rock magnetism and palaeomagnetism of the Montalbano Jonico section (Italy): evidence for late diagenetic growth of greigite and implications for magnetostratigraphy

The Montalbano Jonico (MJ) section, cropping out in Southern Italy, represents a potential candidate to define the Lower/Middle Pleistocene boundary and it has been proposed as a suitable Global Stratotype Section and Point (GSSP) of the Ionian Stage (Middle Pleistocene). The MJ section is the only continuous benthic and planktonic δ18O on-land reference in the Mediterranean area for the Mid-Pleistocene transition, spanning an interval between about 1240 and 645 ka. Combined biostratigraphy and sapropel chronology, tephra stratigraphy and complete high-resolution benthic and planktonic foraminiferal stable oxygen isotope records already provide a firm chronostratigraphic framework for the MJ section. However, magnetostratigraphy was still required to precisely locate the Brunhes-Matuyama transition and to mark the GSSP for the Ionian stage. We carried out a palaeomagnetic study of a subsection (Ideale section) of the MJ composite section, sampling 61 oriented cores from 56 stratigraphic levels spread over a ca. 80-m-thick stratigraphic interval that correlates to the oxygen isotopic stage 19 and should therefore include the Brunhes-Matuyama reversal. The palaeomagnetic data indicate a stable and almost single-component natural remanent magnetization (NRM). A characteristic remanent magnetization (ChRM) was clearly identified by stepwise demagnetization of the NRM. The ChRM declination values vary around 0◦ and the ChRM inclination around the expected value (59◦) for a geocentric axial dipole field at the sampling locality. This result indicates that the section has been remagnetized during the Brunhes Chron. A preliminary study of 27 additional not azimuthally oriented hand samples, collected at various levels from other parts of the MJ composite section, indicates that all the samples are of normal polarity and demonstrates that the remagnetization is widespread across the whole exposed stratigraphic sequence. A series of specific rock magnetic techniques were then applied to investigate the nature of the main magnetic carrier in the study sediments, and they suggest that the main magnetic mineral in the MJ section is the iron sulphide greigite (Fe3S4). Scanning electron microscope observations and elemental microanalysis reveal that greigite occurs both as individual euhedral crystals and in iron sulphides aggregates filling voids in the clay matrix. Therefore, we infer that the remagnetization of the section is due to the late-diagenetic growth of greigite under reducing conditions, most likely resulting in the almost complete dissolution of the original magnetic minerals. Iron sulphide formation in the MJ section can be linked to migration of mineralized fluids. Our inferred timing of the remagnetization associated with greigite growth represents the longest remanence acquisition delay documented in greigite-bearing clays of the Italian peninsula so far

Exploring quantum quasicrystal patterns: a variational study

We study the emergence of quasicrystal configurations produced purely by quantum fluctuations in the ground-state phase diagram of interacting bosonic systems. By using a variational mean-field approach, we determine the relevant features of the pair interaction potential that stabilize such quasicrystalline states in two dimensions. Unlike their classical counterpart, in which the interplay between only two wave vectors determines the resulting symmetries of the solutions, the quantum picture relates in a more complex way to the instabilities of the excitation spectrum. Moreover, the quantum quasicrystal patterns are found to emerge as the ground state with no need of moderate thermal fluctuations. The study extends to the exploration of the excitation properties and the possible existence of super-quasicrystals, i.e. supersolid-like quasicrystalline states in which the long-range non-periodic density profile coexist with a non-zero superfluid fraction. Our calculations show that, in an intermediate region between the homogeneous superfluid and the normal quasicrystal phases, these exotic states indeed exist at zero temperature. Comparison with full numerical simulations provides a solid verification of the variational approach adopted in this work.Comment: 10 pages, 6 Figure