Digital quantum simulation of lattice gauge theories in three spatial dimensions

In the present work, we propose a scheme for digital formulation of lattice gauge theories with dynamical fermions in 3+1 dimensions. All interactions are obtained as a stroboscopic sequence of two-body interactions with an auxiliary system. This enables quantum simulations of lattice gauge theories where the magnetic four-body interactions arising in two and more spatial dimensions are obtained without the use of perturbation theory, thus resulting in stronger interactions compared with analogue approaches. The simulation scheme is applicable to lattice gauge theories with either compact or finite gauge groups. The required bounds on the digitization errors in lattice gauge theories, due to the sequential nature of the stroboscopic time evolution, are provided. Furthermore, an implementation of a lattice gauge theory with a non-abelian gauge group, the dihedral group $D_{3}$, is proposed employing the aforementioned simulation scheme using ultracold atoms in optical lattices.Comment: 38 pages, 5 figure

A gauge redundancy-free formulation of compact QED with dynamical matter for quantum and classical computations

We introduce a way to express compact quantum electrodynamics with dynamical matter on two- and three-dimensional spatial lattices in a gauge redundancy-free manner while preserving translational invariance. By transforming to a rotating frame, where the matter is decoupled from the gauge constraints, we can express the gauge field operators in terms of dual operators. In two space dimensions, the dual representation is completely free of any local constraints. In three space dimensions, local constraints among the dual operators remain but involve only the gauge field degrees of freedom (and not the matter degrees of freedom). These formulations, which reduce the required Hilbert space dimension, could be useful for both numerical (classical) Hamiltonian computations and quantum simulation or computation.Comment: 16 pages, 5 figures, v2: as publishe

A variational Monte Carlo algorithm for lattice gauge theories with continuous gauge groups: a study of (2+1)-dimensional compact QED with dynamical fermions at finite density

Lattice gauge theories coupled to fermionic matter account for many interesting phenomena in both high energy physics and condensed matter physics. Certain regimes, e.g. at finite fermion density, are difficult to simulate with traditional Monte Carlo algorithms due to the so-called sign-problem. We present a variational, sign-problem-free Monte Carlo method for lattice gauge theories with continuous gauge groups and apply it to (2+1)-dimensional compact QED with dynamical fermions at finite density. The variational ansatz is formulated in the full gauge field basis, i.e. without having to resort to truncation schemes for the $U(1)$ gauge field Hilbert space. The ansatz consists of two parts: first, a pure gauge part based on Jastrow-type ansatz states (which can be connected to certain neural-network ansatz states) and secondly, on a fermionic part based on gauge-field dependent fermionic Gaussian states. These are designed in such a way that the gauge field integral over all fermionic Gaussian states is gauge-invariant and at the same time still efficiently tractable. To ensure the validity of the method we benchmark the pure gauge part of the ansatz against another variational method and the full ansatz against an existing Monte Carlo simulation where the sign-problem is absent. Moreover, in limiting cases where the exact ground state is known we show that our ansatz is able to capture this behavior. Finally, we study a sign-problem affected regime by probing density-induced phase transitions.Comment: 14+6 pages, 9+1 figure

Digitalisation and Enterprise Knowledge (net)Working

Social media and emerging mobile technologies have forever changed the landscape of human interaction. Furthermore, they already play a pivotal role also in enterprises as a part of the organisational Knowledge Management System. Almost all large organisations have already implemented at least one Enterprise Social Media tool since they enable collaboration, provide easy access to information, and are available at reasonable costs. The effects of the decoupling of the real and the virtual world (as a result of Social Media use) on the construct knowledge and on knowledge management are still not sufficiently investigated. Against this background, the paper presents an exploratory approach of the development of a specific morphological tableau as an instrument for the analysis of employees’ behavior in context of knowledge management related ESM use. Furthermore, the application of the tableau is exemplary illustrated and further research steps are explained

Real-time dynamics in 2+1d compact QED using complex periodic Gaussian states

We introduce a class of variational states to study ground state properties and real-time dynamics in (2+1)-dimensional compact QED. These are based on complex Gaussian states which are made periodic in order to account for the compact nature of the $U(1)$ gauge field. Since the evaluation of expectation values involves infinite sums, we present an approximation scheme for the whole variational manifold. We calculate the ground state energy density for lattice sizes up to $20 \times 20$ and extrapolate to the thermodynamic limit for the whole coupling region. Additionally, we study the string tension both by fitting the potential between two static charges and by fitting the exponential decay of spatial Wilson loops. As the ansatz does not require a truncation in the local Hilbert spaces, we analyze truncation effects which are present in other approaches. The variational states are benchmarked against exact solutions known for the one plaquette case and exact diagonalization results for a $\mathbb{Z}_3$ lattice gauge theory. Using the time-dependent variational principle, we study real-time dynamics after various global quenches, e.g. the time evolution of a strongly confined electric field between two charges after a quench to the weak-coupling regime. Up to the points where finite size effects start to play a role, we observe equilibrating behavior.Comment: 20 pages, 16 figures, v2: as publishe

Respuesta hidrodinámica de un plasma en una fulguración solar

Se propone un modelo hidrodinámico para fulguraciones solares confinadas, suponiendo que la energía es liberada en forma de calor en el ápice de un arco magnético o loop (fuente térmica). El cálculo numérico que se realiza es lagrangiano, en contraste con modelos anteriores que son eulerianos. Debido a que la presión magnética es mucho mayor que la de plasma, trabajamos con loops rígidos que confinan al gas. Se puede observar a lo largo de la simulación un frente conductivo térmico que desciende hacía la cromosfera solar, elevando la temperatura del plasma. Este plasma caliente emite en rayos X blandos (región coronal) y en EUV (región de transición). También se observa material cromosférico que se expande hacia la corona, debido a los gradientes de presión que aparecen durante ia evolución del plasma. Los perfiles de líneas de emisión en rayos X blandos (CaXIX) y EUV (NV) que surgen del modelo son comparados con las observaciones. Se sugieren también algunas modificaciones al modelo que corrigen algunas discrepancias con las observaciones. También se analizan las mejoras introducidas por el tratamiento lagrangiano de la simulación numérica.Asociación Argentina de Astronomí

Transcranial magnetic stimulation in the treatment of adolescent depression: a systematic review and meta-analysis of aggregated and individual-patient data from uncontrolled studies.

Transcranial magnetic stimulation (TMS) is a non-invasive treatment for adolescent major depressive disorder (MDD). Existing evidence on the efficacy of TMS in adolescent MDD awaits quantitative synthesis. A systematic literature search was conducted, and data from eligible studies were synthesized using random-effects models. Treatment-covariate interactions were examined in exploratory analyses of individual-patient data (IPD). Systematic search of the literature yielded 1264 hits, of which 10 individual studies (2 randomized trials) were included for quantitative synthesis of mainly uncontrolled studies. Individual patient data (IPD) were available from five trials (all uncontrolled studies). Quantitative synthesis of aggregated data revealed a statistically significant negative overall standardized mean change (pooled SMCC = 2.04, 95% CI [1.46; 2.61], SE = 0.29, p < .001), as well as a significant overall treatment response rate (Transformed Proportion = 41.30%, 95% CI [31.03; 51.57], SE = 0.05; p < 0.001), considering data from baseline to post-treatment. Exploratory IPD analyses suggests TMS might be more effective in younger individuals and individuals with more severe depression, and efficacy might be enhanced with certain treatment modality settings, including higher number of TMS sessions, longer treatment durations, and unilateral and not bilateral stimulation. Existing studies exhibit methodological shortcomings, including small-study effects and lack of control group, blinding, and randomization-compromising the credibility of the present results. To date, two randomized controlled trials on TMS in adolescent depression have been published, and the only large-scale randomized trial suggests TMS is not more effective than sham stimulation. Future large-scale, randomized, and sham-controlled trials are warranted. Future trials should ensure appropriate selection of patients for TMS treatment and guide precision medicine approaches for stimulation protocols

p166 links membrane and intramitochondrial modules of the trypanosomal tripartite attachment complex.

The protist parasite Trypanosoma brucei has a single mitochondrion with a single unit genome termed kinetoplast DNA (kDNA). Faithfull segregation of replicated kDNA is ensured by a complicated structure termed tripartite attachment complex (TAC). The TAC physically links the basal body of the flagellum with the kDNA spanning the two mitochondrial membranes. Here, we characterized p166 as the only known TAC subunit that is anchored in the inner membrane. Its C-terminal transmembrane domain separates the protein into a large N-terminal region that interacts with the kDNA-localized TAC102 and a 34 aa C-tail that binds to the intermembrane space-exposed loop of the integral outer membrane protein TAC60. Whereas the outer membrane region requires four essential subunits for proper TAC function, the inner membrane integral p166, via its interaction with TAC60 and TAC102, would theoretically suffice to bridge the distance between the OM and the kDNA. Surprisingly, non-functional p166 lacking the C-terminal 34 aa still localizes to the TAC region. This suggests the existence of additional TAC-associated proteins which loosely bind to non-functional p166 lacking the C-terminal 34 aa and keep it at the TAC. However, binding of full length p166 to these TAC-associated proteins alone would not be sufficient to withstand the mechanical load imposed by the segregating basal bodies

Nano-​cuprous oxide catalyzed one-​pot synthesis of a carbazole-​based STAT3 inhibitor: a facile approach via intramolecular C-​N bond formation reactions

In this study, we report the one-​pot synthesis of substituted carbazole derivs. using nano cuprous oxide as a catalyst via intramol. C-​N bond forming reactions. Among the synthesized carbazoles, 3'-​((3-​acetyl-​6-​chloro-​9H-​carbazol-​9-​yl)​methyl)​-​[1,​1'-​biphenyl]​-​2-​carbonitrile (ACB) was identified as a lead antiproliferative agent against lung cancer cell lines A549 and LLC with an IC50 of 13.6 and 16.4 μM resp. Furthermore, we found that the lead compd. suppresses the constitutive phosphorylation of STAT3 (Tyr-​705) in A549, HCC-​2279 and H1975 cells. We analyzed the levels of phospho-​STAT3 and LSD1 in the nuclear ext. of ACB treated HCC-​2279 cells to evaluate the transcriptional activity of STAT3. We found the downregulation of phospho-​STAT3 without any change in the expression of LSD1 indicating that ACB downregulates the transcriptional activity of STAT3. Mol. docking anal. revealed that ACB makes a favorable interaction with Arg-​609 and Ser-​613 in the pTyr site of the SH2 domain of STAT3

Methods to estimate the between-study variance and its uncertainty in meta-analysis

Meta‐analyses are typically used to estimate the overall/mean of an outcome of interest. However, inference about between‐study variability, which is typically modelled using a between‐study variance parameter, is usually an additional aim. The DerSimonian and Laird method, currently widely used by default to estimate the between‐study variance, has been long challenged. Our aim is to identify known methods for estimation of the between‐study variance and its corresponding uncertainty, and to summarise the simulation and empirical evidence that compares them. We identified 16 estimators for the between‐study variance, seven methods to calculate confidence intervals, and several comparative studies. Simulation studies suggest that for both dichotomous and continuous data the estimator proposed by Paule and Mandel and for continuous data the restricted maximum likelihood estimator are better alternatives to estimate the between‐study variance. Based on the scenarios and results presented in the published studies, we recommend the Q‐profile method and the alternative approach based on a ‘generalised Cochran between‐study variance statistic’ to compute corresponding confidence intervals around the resulting estimates. Our recommendations are based on a qualitative evaluation of the existing literature and expert consensus. Evidence‐based recommendations require an extensive simulation study where all methods would be compared under the same scenarios. © 2015 The Authors. Research Synthesis Methods published by John Wiley & Sons Ltd