Hamiltonian quantum simulation with bounded-strength controls

We propose dynamical control schemes for Hamiltonian simulation in many-body quantum systems that avoid instantaneous control operations and rely solely on realistic bounded-strength control Hamiltonians. Each simulation protocol consists of periodic repetitions of a basic control block, constructed as a suitable modification of an "Eulerian decoupling cycle," that would otherwise implement a trivial (zero) target Hamiltonian. For an open quantum system coupled to an uncontrollable environment, our approach may be employed to engineer an effective evolution that simulates a target Hamiltonian on the system, while suppressing unwanted decoherence to the leading order. We present illustrative applications to both closed- and open-system simulation settings, with emphasis on simulation of non-local (two-body) Hamiltonians using only local (one-body) controls. In particular, we provide simulation schemes applicable to Heisenberg-coupled spin chains exposed to general linear decoherence, and show how to simulate Kitaev's honeycomb lattice Hamiltonian starting from Ising-coupled qubits, as potentially relevant to the dynamical generation of a topologically protected quantum memory. Additional implications for quantum information processing are discussed.Comment: 24 pages, 5 color figure

A sequential update algorithm for computing the stationary distribution vector in upper block-Hessenberg Markov chains

This paper proposes a new algorithm for computing the stationary distribution vector in continuous-time upper block-Hessenberg Markov chains. To this end, we consider the last-block-column-linearly-augmented (LBCL-augmented) truncation of the (infinitesimal) generator of the upper block-Hessenberg Markov chain. The LBCL-augmented truncation is a linearly-augmented truncation such that the augmentation distribution has its probability mass only on the last block column. We first derive an upper bound for the total variation distance between the respective stationary distribution vectors of the original generator and its LBCL-augmented truncation. Based on the upper bound, we then establish a series of linear fractional programming (LFP) problems to obtain augmentation distribution vectors such that the bound converges to zero. Using the optimal solutions of the LFP problems, we construct a matrix-infinite-product (MIP) form of the original (i.e., not approximate) stationary distribution vector and develop a sequential update algorithm for computing the MIP form. Finally, we demonstrate the applicability of our algorithm to BMAP/M/$\infty$ queues and M/M/$s$ retrial queues.Comment: The typo in Abstract has been correcte

The Canadian Cluster Comparison Project: detailed study of systematics and updated weak lensing masses

Masses of clusters of galaxies from weak gravitational lensing analyses of ever larger samples are increasingly used as the reference to which baryonic scaling relations are compared. In this paper we revisit the analysis of a sample of 50 clusters studied as part of the Canadian Cluster Comparison Project. We examine the key sources of systematic error in cluster masses. We quantify the robustness of our shape measurements and calibrate our algorithm empirically using extensive image simulations. The source redshift distribution is revised using the latest state-of-the-art photometric redshift catalogs that include new deep near-infrared observations. Nonetheless we find that the uncertainty in the determination of photometric redshifts is the largest source of systematic error for our mass estimates. We use our updated masses to determine b, the bias in the hydrostatic mass, for the clusters detected by Planck. Our results suggest 1-b=0.76+-0.05(stat)}+-0.06(syst)}, which does not resolve the tension with the measurements from the primary cosmic microwave background.Comment: resubmitted to MNRAS after review by refere

Concurrent p53 mutation in EGFR mutant non-small cell lung cancer is associated with resistance to first and second generation EGFR tyrosine kinase inhibitors, a meta-analysis

Epidermal growth factor receptor (EGFR) mutant lung cancers tend to respond well to EGFR tyrosine kinase inhibitors (TKIs). However, resistance has been described. Molecular studies have revealed that concurrent mutations of tumor driver genes are associated with TKI resistance. To delineate the role of concurrent mutation of tumor suppressor gene p53 in TKI resistance, a meta-analysis was performed using published observations of EGFR mutant lung cancer patients treated with first or second generation TKIs. 31 studies are included in the analysis following a search of PubMed. Probability of TKI resistance and progress free survival (PFS) were compared in patients with or without p53 mutation. An increased probability of TKI resistance is seen in p53 mutant lung cancers. Interestingly, when resistance is defined as PFSmonths, there is insignificant increase of resistance in p53 mutant patients (OR=1.93, 95% CI [0.38, 9.85], p=0.43). When resistance is defined as PFS(OR=20.16, 95% CI [2.61, 155.75], p=0.004). In addition, p53 mutation is associated with a significantly shortened progress free survival in these patients (HR=1.57, 95% CI [1.26,1.97], p\u3c0.0001)

Assisting Communities to Access EU Funds for Inclusion

National governments in Europe can greatly enhance the implementation of their National Roma Integration Strategies and social inclusion more broadly. One proven way of doing this is by providing assistance to local authorities and organizations to access and implement projects financed by European Structural and Investment Funds.The Making the Most of EU Funds for Roma Program of the Open Society Foundations has worked for more than five years with local communities to leverage EU funds for social inclusion projects targeting Roma, as well as other disadvantaged communities. This paper summarizes the experiences and methodologies employed by the program, bearing in mind that national authorities—particularly in new member states benefiting from Structural Funds—might be keen to replicate a similar model to advance their own social inclusion goals.National governments can establish similar support mechanisms for local communities in order to intensify local spending of EU funds for social inclusion. This assistance is most relevant for EU Member States with sizeable Roma communities including Bulgaria, Czech Republic, Hungary, Romania, and Slovakia

Programming the Structural Funds for Roma Inclusion in 201420

The new 2014–20 EU budget period is the first to start with Roma inclusion high on the European agenda. The regulations on EU funds, adopted in December last year, create favorable conditions for launching ambitious policy reforms benefiting equality and Roma inclusion with support from EU funds.The relevant national level operational programs, to be finalized and adopted in the coming months, should take advantage of these favorable conditions and commit to policy reforms, such as investing in early childhood development; providing quality, desegregated education services that equip disadvantaged children for labor market participation; providing personalized employment services that are able to address multiple disadvantages; and strengthening access to primary health care services for marginalized communities in remote areas.Operational programs should also commit to changes in structures and procedures allocating EU funds, e.g., by setting up strong equality policy units, using simplified cost options, and launching global grants and capacity-building services.The Making the Most of EU Funds for Roma program of the Open Society Foundations contributes to the programming of Structural Funds for Roma Inclusion with this toolkit. The aim of the toolkit is to assist public authorities involved in the programming by describing not just what should be done but also how these can be don

Chlamydia pneumoniae infection acts as an endothelial stressor with the potential to initiate the earliest heat shock protein 60-dependent inflammatory stage of atherosclerosis

We identified increased expression and redistribution of the intracellular protein 60-kDa human heat shock protein (hHSP60) (HSPD1) to the cell surface in human endothelial cells subjected to classical atherosclerosis risk factors and subsequent immunologic cross-reactivity against this highly conserved molecule, as key events occurring early in the process of atherosclerosis. The present study aimed at investigating the role of infectious pathogens as stress factors for vascular endothelial cells and, as such, contributors to early atherosclerotic lesion formation. Using primary donor-matched arterial and venous human endothelial cells, we show that infection with Chlamydia pneumoniae leads to marked upregulation and surface expression of hHSP60 and adhesion molecules. Moreover, we provide evidence for an increased susceptibility of arterial endothelial cells for redistribution of hHSP60 to the cellular membrane in response to C. pneumoniae infection as compared to autologous venous endothelial cells. We also show that oxidative stress has a central role to play in endothelial cell activation in response to chlamydial infection. These data provide evidence for a role of C. pneumoniae as a potent primary endothelial stressor for arterial endothelial cells leading to enrichment of hHSP60 on the cellular membrane and, as such, a potential initiator of atherosclerosi

A preliminary snapshot investigation of the marine soundscape for Malta : a stepping stone towards achieving ‘good ecological status’

The ever-accelerating rate of research focusing on the issue of underwater noise pollution, particularly concerning low-frequency, continuous noise, has steadily been unveiling the myriad of detrimental ecological implications caused to marine life. Despite this, many European Member States, such as Malta, still lack solid monitoring and regulatory frameworks aimed at characterising and improving the state of the marine acoustic environment and achieving ‘Good Ecological Status’ in accordance with the Marine Strategy Framework Directive. This shortcoming is directly reflected in the complete absence of baseline information covering the quality of the national soundscape. This paper aims to serve as a preliminary investigation into continuous underwater noise generation within Maltese waters, focusing on two sites characterised by heavy marine activity: Cirkewwa and the Grand Harbour. Digital signal processing software packages (dBWav version 1.3.4) were used to extract and analyse sound pressure levels from in situ recorded audio files. Further statistical analysis was also carried out so as to evaluate the resultant snapshot of the baseline marine soundscapes at both sites. Furthermore, AIS data were used to tentatively identify the identifiable sources of underwater noise pollution. Given the current information lacuna revolving around the issue of underwater noise pollution in Malta, this paper may serve as a pilot study, with the aim of bridging this knowledge gap and forming the basis of future national research for Maltese marine conservation.peer-reviewe

Object Classificators Using the AdaBoost Algorithm and Neural Networks

The construction of image object detectors is still a relevant task, due to dynamic developments in the field of computer vision. In this work, we combined neural network technologies with existing data processing algorithms to obtain effective object classifiers. We demonstrate our approach on the example of face detection

Mechanical Characterisation of Woven Pneumatic Active Textile

Active textiles have shown promising applications in soft robotics owing to their tunable stiffness and design flexibility. Given the breadth of the design space for planar and spatial arrangements of these woven structures, a rigorous and generalizable characterisation of these systems is not yet available. In order to characterize the response of a stereotypical woven pattern to actuation, we undertake a parametric study of plain weave active fabrics and characterise their mechanical properties in accordance with the relevant ISO standards for varying muscle densities and both monotonically increasing/decreasing pressures. Tensile and flexural tests were undertaken on five plain weave samples made of a nylon 6 (polyamide) warp and EM20 McKibben S-muscle weft, for input pressures ranging from 0.00 MPa to 0.60 MPa, at three muscle densities, namely 100 m−1 , 74.26 m−1 and 47.62 m−1 . Contrary to intuition, we find that a lower muscle density has a more prominent impact on the thickness, but a significantly lesser one on length, highlighting a critical dependency on the relative orientation among the loading, the passive textile and the muscle filaments. Hysteretic behaviour as large as 10% of the longitudinal contraction is observed on individual filaments and woven textiles, and its onset is identified in the shear between the rubber tube and the outer sleeve of the artificial muscle. Hysteresis is shown to be muscle density-dependent and responsible for a strongly asymmetrical response upon different pressure inputs. These findings provide new insights into the mechanical properties of active textiles with tunable stiffness, and may contribute to future developments in wearable technologies and biomedical devices