Bipartite entanglement of quantum states in a pair basis

The unambiguous detection and quantification of entanglement is a hot topic of scientific research, though it is limited to low dimensions or specific classes of states. Here we identify an additional class of quantum states, for which bipartite entanglement measures can be efficiently computed, providing new rigorous results. Such states are written in arbitrary $d\times d$ dimensions, where each basis state in the subsystem A is paired with only one state in B. This new class, that we refer to as pair basis states, is remarkably relevant in many physical situations, including quantum optics. We find that negativity is a necessary and sufficient measure of entanglement for mixtures of states written in the same pair basis. We also provide analytical expressions for a tight lower-bound estimation of the entanglement of formation, a central quantity in quantum information.Comment: 8 pages, 10 figure

Hidden XY structure of the bond-charge Hubbard model

The repulsive one-dimensional Hubbard model with bond-charge interaction (HBC) in the superconducting regime is mapped onto the spin-1/2 XY model with transverse field. We calculate correlations and phase boundaries, realizing an excellent agreement with numerical results. The critical line for the superconducting transition is shown to coincide with the analytical factorization line identifying the commensurate-incommensurate transition in the XY model.Comment: 4 pages, 3 figure

Brane parity orders in the insulating state of Hubbard ladders

The Mott insulating state of the Hubbard model at half-filling could be depicted as a spin liquid of singly occupied sites with holon-doublon quantum fluctuations localized in pairs. In one dimension the behavior is captured by a finite value of the charge parity string correlator, which fails to remain finite when generalized to higher dimensions. We recover a definition of parity brane correlator which may remain nonvanishing in presence of interchain coupling, by assigning an appropriate fractional phase to the parity breaking fluctuations. In case of Hubbard ladders at half-filling, we find that the charge parity brane is non-zero at any repulsive value of interaction. The spin parity brane instead becomes nonvanishing in the even-leg case, in correspondence to the onset of the spin gapped D-Mott phase, which is absent in the odd-leg case. The behavior of the parity correlators is also analyzed by means of a numerical DMRG analysis of the one- and two-leg ladder.Comment: Main article: 5 pages, 1 figure. Supplementary information: 4 pages, 8 figure

How hidden orders generate gaps in one-dimensional fermionic systems

We demonstrate that hidden long range order is always present in the gapped phases of interacting fermionic systems on one dimensional lattices. It is captured by correlation functions of appropriate nonlocal charge and/or spin operators, which remain asymptotically finite. The corresponding microscopic orders are classified. The results are confirmed by DMRG numerical simulation of the phase diagram of the extended Hubbard model, and of a Haldane insulator phas

An Innovative Approach to Kinematic Analysis of Multibody Hydraulic Actuation Systems

The paper focuses on the development of an innovative methodology for the direct measurement of the main kinematic variables in multi-body hydraulic actuation systems. The analysis investigates how the motion capture technique has been applied to the experimental determination of position, velocity and acceleration of hydraulically controlled actuation systems for off-highway machineries. A number of earth-moving machines has been taken into account, in particular a mini-excavator articulated harm has been equipped with both a standard mechanical system for position and acceleration measurement (including different accelerometers, linear and angular transducers), and a set of IR markers for motion capture application. First, the hydraulically controlled boom-arm-bucket system has been operated using a control routine reproducing a reference operating condition, in order to define the accuracy of the motion capture system in detecting the kinematic quantities\u2019 variations. At the same time, the hydraulic variables have been also acquired to monitor the behavior during the machine working routine. Thus, the results obtained by the different experimental techniques have been compared, in order to state the reliability of the motion capture technique to predict the fast dynamics of pressure variations through the accurate measurement of mechanical devices\u2019 oscillation. Finally, the paper reports the main results obtained using the data from the motion capture characterization of the dynamic performance of the mini-excavator, with particular attention devoted to the dynamic analysis through lumped and distributed parameter numerical co-simulation

Effect of allogeneic intraoperative blood transfusion on survival in patients treated with radical cystectomy for nonmetastatic bladder cancer: Results from a single high-volume institution

Transfusion has been related to poor survival after surgery in several cancers. Recently, timing of transfusion has been proposed as crucial in the determination of poor survival expectanies after surgery, in fact, intra- operative but not postoperative transfusion were found to be related. We confirmed these findings in patients who underwent radical cystectomy because of bladder cancer; physicians should avoid use of transfusion intraoperatively. Background: Previous studies have demonstrated that perioperative blood transfusion (BT) is associated with a significantly increased risk of cancer recurrence and mortality after radical cystectomy (RC). Recently, it was shown for the first time that intraoperative transfusion has a detrimental effect on cancer survival. The aim of the current study was to validate this finding in a single European institution. Patients and Methods: The study focused on 1490 consecutive nonmetastatic bladder cancer patients treated with RC at a single tertiary care referral center between January 1990 and August 2013. KaplaneMeier analyses and Cox regression analyses were used to assess the effect of timing of BT administration (no transfusion vs. intraoperative transfusion vs. postoperative transfusion vs. intra- operative and postoperative transfusion) on cancer-specific mortality (CSM), overall mortality (OM), and disease recurrence. Results: Mean age at the time of RC was 67 years. Overall, 322 (21.6%) patients received intraoperative BT and 97 (6.5%) received postoperative BT. At a mean follow-up time of 125 months (median, 110 months), the 5- and 10-year CSM rate was 846 (58%) and 715 (48%), respectively. In multivariable analyses patients who received intraoperative BT had greater risk of disease recurrence (hazard ratio [HR], 1.24; P .2). Conclusion: Our study confirms that intraoperative, but not postoperative BT, are related to a detrimental effect on survival after RC. These results should be take into account by physicians to administer BT using the correct timing

Multi-phase and Multi-component CFD Analysis of a Load - Sensing Proportional Control Valve

The paper analyzes the flow through a directional control valve for load –sensing application by means of a multi-phase and multi-component CFD approach. Numerical modeling includes both cavitation and aeration; in particular, the Rayleigh-Plesset equation and the inertia controlled growth model for bubble formation are adopted. The effects of gas release and vapor formation as well as turbulence on the main valve metering characteristics are investigated. The results show a remarkable influence of the aeration phenomena on the recirculating zones downstream of the metering area and thus on the cavitation onset region

Energy recovery of the biomass from livestock farms in Italy: the case of Modena Province

The energy recovery from manure of different Italian livestock farms is analysed by means of numerical simulation using an in-house developed code. In particular, the animal farming in the province of Modena is taken into account and biomass is exploited in an integrated system including different waste to energy technologies. In the considered system, the manure of a number of types of animals is fed into an anaerobic digester, while the digested sludge is separated into the solid and liquid fractions. The former is employed as a fuel in a downdraft gasifier, while the latter is purified by means of both forward and inverse osmosis. Finally, the obtained bio-gas and syngas are used in a cogeneration system based on a spark ignition internal combustion engine to produce electric and thermal power. The potential power production of the considered territory is estimated and compared with the energy requirements of the animal farms. Different strategies for the distributed exploitation of the manure versus a centralized solution are investigated and the relating plant size and production of electric energy and thermal energy are evaluated

A Combined Methodology for Studying the Axial Balancing Mechanism of Orbit Annular Hydraulic Machines

A customized combined methodology, based on both 2D CFD and lumped parameters numerical modeling, useful for simulating the hydraulic behavior of orbit annular machines, has been developed and here presented. More in details, the predictive capabilities of this CAE tool can be applied for the study of both roller and gerotor architectures and considering both pumping and motoring operating mode. First of all, a in-house developed 2D CFD methodology, based on the integration of the stationary form of the Reynolds equation for the determination of the pressure distribution inside the lateral clearances bounded by the sides of the stator-rotor group and the valve plate, as well as the internal manifold surface, is firstly presented and applied. The same computational procedure has been also involved for the investigation of the leakages through the clearance between the valve plate and the balancing ring. After that, a lumped and distributed parameters numerical model has been involved for the simulation of a typical orbit roller motor operation. In this case, particular care has been devoted to the modeling of the axial leakage clearances, adopting analytical interpolation functions deducted from the numerical results calculated applying the previously described 2D CFD methodology. Finally, the whole CAE approach has been validated by means of a comprehensive numerical vs. experimental comparison, obtaining a general good accordance for the overall operating field of this particular type of hydraulic unit

Non-local order parameters for the 1D Hubbard model

We characterize the Mott insulator and Luther-Emery phases of the 1D Hubbard model through correlators that measure the parity of spin and charge strings along the chain. These non-local quantities order in the corresponding gapped phases and vanish at the critical point $U_c=0$. The Mott insulator consists of bound doublon-holon pairs, which in the Luther-Emery phase turn into electron pairs with opposite spins, both unbinding at $U_c$. The behavior of the parity correlators can be captured by an effective free spinless fermion model.Comment: 4 pages; 3 figure