Adiabatic Quantum Simulators

In his famous 1981 talk, Feynman proposed that unlike classical computers, which would presumably experience an exponential slowdown when simulating quantum phenomena, a universal quantum simulator would not. An ideal quantum simulator would be controllable, and built using existing technology. In some cases, moving away from gate-model-based implementations of quantum computing may offer a more feasible solution for particular experimental implementations. Here we consider an adiabatic quantum simulator which simulates the ground state properties of sparse Hamiltonians consisting of one- and two-local interaction terms, using sparse Hamiltonians with at most three-local interactions. Properties of such Hamiltonians can be well approximated with Hamiltonians containing only two-local terms. The register holding the simulated ground state is brought adiabatically into interaction with a probe qubit, followed by a single diabatic gate operation on the probe which then undergoes free evolution until measured. This allows one to recover e.g. the ground state energy of the Hamiltonian being simulated. Given a ground state, this scheme can be used to verify the QMA-complete problem LOCAL HAMILTONIAN, and is therefore likely more powerful than classical computing.Comment: 9 pages, 1 figur

An epidemiological model with voluntary quarantine strategies governed by evolutionary game dynamics

During pandemic events, strategies such as social distancing can be fundamental to curb viral spreading. Such actions can reduce the number of simultaneous infections and mitigate the disease spreading, which is relevant to the risk of a healthcare system collapse. Although these strategies can be suggested, their actual implementation may depend on the population perception of the disease risk. The current COVID-19 crisis, for instance, is showing that some individuals are much more prone than others to remain isolated, avoiding unnecessary contacts. With this motivation, we propose an epidemiological SIR model that uses evolutionary game theory to take into account dynamic individual quarantine strategies, intending to combine in a single process social strategies, individual risk perception, and viral spreading. The disease spreads in a population whose agents can choose between self-isolation and a lifestyle careless of any epidemic risk. The strategy adoption is individual and depends on the perceived disease risk compared to the quarantine cost. The game payoff governs the strategy adoption, while the epidemic process governs the agent's health state. At the same time, the infection rate depends on the agent's strategy while the perceived disease risk depends on the fraction of infected agents. Results show recurrent infection waves, which were seen in previous epidemic scenarios with quarantine. Notably, the risk perception is found to be fundamental for controlling the magnitude of the infection peak, while the final infection size is mainly dictated by the infection rates. Low awareness leads to a single and strong infection peak, while a greater disease risk leads to shorter, although more frequent, peaks. The proposed model spontaneously captures relevant aspects of a pandemic event, highlighting the fundamental role of social strategies

Extensional flow of Newtonian and Boger fluids through a flow focusing microdevice

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.In this work we perform a numerical and experimental study on the flow of Newtonian and viscoelastic fluids through a microfluidic device in which hydrodynamic flow focusing is produced using two balanced lateral sheath streams that shape a third inlet stream. The flow focusing device used was conceived to achieve a nearly constant extensional rate along the centerline and is shaped much like a conventional cross-slot except for comprising three inlets and one exit channel. The work undertaken comprises experimental flow visualization as well as 2D and 3D numerical calculations using a finite volume method. The Newtonian fluid used in the experiments was distilled water and the viscoelastic fluid was an aqueous solution containing 125 ppm (w/w) of polyacrylamide (PAA, Mw = 18×10(6) g/mol), to which 1% of salt (NaCl) was added. The addition of salt to a shear-thinning PAA solution resulted in a low viscosity Boger fluid, i.e., a viscoelastic fluid with a nearly constant viscosity. The combination of small length scales characteristic of microfluidics with this type of fluid allows us to observe strong elastic effects in the absence of shear-thinning and inertial effects (or at least when these effects are weak). We report a rich variety of flow features, which depend on the fluid used as well as on the operational conditions. Additionally, we show good qualitative agreement between the experimental observations and the numerical predictions.FCT, FEDER and COMPETE for financial support through projects REEQ/262/EME/2005, REEQ/928/EME/2005 and PTDC/EME-MFE/099109/2008

Simulations of extensional flow in microrheometric devices

We present a detailed numerical study of the flow of a Newtonian fluid through microrheometric devices featuring a sudden contraction–expansion. This flow configuration is typically used to generate extensional deformations and high strain rates. The excess pressure drop resulting from the converging and diverging flow is an important dynamic measure to quantify if the device is intended to be used as a microfluidic extensional rheometer. To explore this idea, we examine the effect of the contraction length, aspect ratio and Reynolds number on the flow kinematics and resulting pressure field. Analysis of the computed velocity and pressure fields show that, for typical experimental conditions used in microfluidic devices, the steady flow is highly three-dimensional with open spiraling vortical structures in the stagnant corner regions. The numerical simulations of the local kinematics and global pressure drop are in good agreement with experimental results. The device aspect ratio is shown to have a strong impact on the flow and consequently on the excess pressure drop, which is quantified in terms of the dimensionless Couette and Bagley correction factors. We suggest an approach for calculating the Bagley correction which may be especially appropriate for planar microchannels

Boger fluid flow through hyperbolic contraction microchannels

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Boger fluids are characterized by their constant viscosity and elasticity and are very useful to study pure elastic flow behavior. In this paper we assess the potential of a microfluidic hyperbolic contraction as a device to measure the relaxation time of low viscosity polymer solutions, which are difficult to characterize in a conventional capillary break-up extensional rheometer. For this purpose we initially characterize the shear and extensional rheology of aqueous solutions of polyacrylamide (PAA) at different concentrations (400, 250, 125 and 50 ppm) with 1% (w/w) of NaCl, which result in low viscosity Boger fluids. Subsequently, flow visualizations of their flow through a microfluidic hyperbolic contraction were carried out in order to quantify the relation between their degree of elasticity and the vortex growth upstream of the microchannel.Fundação para a Ciência e a Tecnologia (FCT), COMPETE and FEDER through projects PTDC/ EQU-FTT/ 71800/2006, PTDC/EQUFTT/ 70727/2006, PTDC/EME-MFE/099109/ 2008, REEQ/928/EME/2005 and REEQ/298/EME/2005

Primary gastric plasmacytoma: a rare entity

Extramedullary plasmacytomas (EP) are tumours composed by a monoclonal population of plasma cells that arise in extraosseus tissues, comprising <5% of all plasma cell neoplasms. Usually, EP arise in the head and neck region, and the stomach is the second most common location-gastric plasmacytoma (GP). Clinical and radiological manifestations are unspecific and may mimic other tumours like gastric adenocarcinomas, gastric stromal tumours and lymphomas, mainly marginal cell lymphoma (MALT lymphoma) and usually definitive diagnosis is provided by pathological evaluation. We present a case of primary GP, discovered incidentally as a polypoid lesion. Tumour was composed by sheets of mature and immature plasmocytes positive for CD138 on immunohistochemistry, without Helicobacter pylori identification. The patient is alive 6 years later and without tumour relapse.info:eu-repo/semantics/publishedVersio

Induced liver injury after high-dose methylprednisolone in a patient with multiple sclerosis

A 33-year-old woman with multiple sclerosis, medicated with high doses of methylprednisolone, cyclophosphamide and glatiramer acetate, was referred to our department due to acute liver injury. The laboratory investigation was normal except for weakly positive antinuclear antibodies. Cyclophosphamide and glatiramer acetate were suspended, and intravenous immunoglobulin with maintenance of high doses of methylprednisolone was initiated. The patient developed another episode of acute hepatitis so the immunoglobulin was stopped. After that, she had three more episodes of elevation of liver enzymes with no hepatic insufficiency while medicated only with high doses of methylprednisolone. At this time, liver biopsy showed focal centrilobubar hepatocyte necrosis with minimal interface hepatitis. After the high doses of methylprednisolone were suspended, the patient remained asymptomatic, with normal hepatic enzymes. This case emphasises that, although rare, induced liver injury after high doses of methylprednisolone can occur.info:eu-repo/semantics/publishedVersio

Processing parameters in laser powder bed fusion metal additive manufacturing

JPO acknowledges Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the projects UIDB/00667/2020 and UIDB/50025/2020 .As metallic additive manufacturing grew in sophistication, users have requested greater control over the systems, namely the ability to fully change the process parameters. The goal of this manuscript is to review the effects of major process parameters on build quality (porosity, residual stress, and composition changes) and materials properties (microstructure and microsegregation), and to serve as a guide on how these parameters may be modified to achieve specific design goals for a given part. The focus of this paper is on laser powder bed fusion, but elements can be applied to electron beam powder bed fusion or direct energy deposition techniques.publishersversionpublishe

Microchannels analogues for the study of viscoelastic fluid flows through porous media

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.This work studies the flow behavior and related pressure losses of viscoelastic polymer solutions in microchannels with two different sequences of contraction/expansion, disposed in a symmetric and an asymmetric arrangement, respectively. These microfluidic devices are proposed as simplified microchannel analogues for the flow of Newtonian and viscoelastic fluids through porous media. The results show that the symmetric configuration mimics the pressure gradient of these polymer solutions through a porous medium at low flow rates (below a critical Deborah number, Decr), while the asymmetric arrangement gives the asymptotic limit at high De values (above Decr) as a consequence of the intrinsic differences in the extensional rate profiles defined by each microgeometry.Fundação para a Ciência e a Tecnologia (FCT), COMPETE and FEDER through projects PTDC/ EQU-FTT/ 71800/ 2006, PTDC/EQUFTT/ 70727/ 2006, PTDC/ EME-MFE/ 99109/ 2008 and REEQ/ 262/ EME/ 2005

Biochemical and molecular mechanisms of plant-microbe-metal interactions: relevance for phytoremediation

Plants and microbes coexist or compete for survival and their cohesive interactions play a vital role in adapting to metalliferous environments, and can thus be explored to improve microbe-assisted phytoremediation. Plant root exudates are useful nutrient and energy sources for soil microorganisms, with whom they establish intricate communication systems. Some beneficial bacteria and fungi, acting as plant growth promoting microorganisms (PGPMs), may alleviate metal phytotoxicity and stimulate plant growth indirectly via the induction of defense mechanisms against phytopathogens, and/or directly through the solubilization of mineral nutrients (nitrogen, phosphate, potassium, iron, etc.), production of plant growth promoting substances (e.g., phytohormones), and secretion of specific enzymes (e.g., 1-aminocyclopropane-1-carboxylate deaminase). PGPM can also change metal bioavailability in soil through various mechanisms such as acidification, precipitation, chelation, complexation, and redox reactions. This review presents the recent advances and applications made hitherto in understanding the biochemical and molecular mechanisms of plant-microbe interactions and their role in the major processes involved in phytoremediation, such as heavy metal detoxification, mobilization, immobilization, transformation, transport, and distribution.info:eu-repo/semantics/publishedVersio