qqˉq\bar q interaction in light-cone gauge formulations of Yang-Mills theory in 1+1 dimensions

A rectangular Wilson loop with sides parallel to space and time directions is perturbatively evaluated in two light-cone gauge formulations of Yang-Mills theory in 1+1 dimensions, with ``instantaneous'' and ``causal'' interactions between static quarks. In the instantaneous formulation we get Abelian-like exponentiation of the area in terms of $C_F$. In the ``causal'' formulation the loop depends not only on the area, but also on the dimensionless ratio $\beta = {L \over T}$, $2L$ and $2T$ being the lengths of the rectangular sides. Besides it also exhibits dependence on $C_A$. In the limit $T \to \infty$ the area law is recovered, but dependence on $C_A$ survives. Consequences of these results are pointed out.Comment: 30 pages, latex, one figure included as a ps file, an Erratum include

Effective Edge-Fault-Tolerant Single-Source Spanners via Best (or Good) Swap Edges

Computing \emph{all best swap edges} (ABSE) of a spanning tree $T$ of a given $n$-vertex and $m$-edge undirected and weighted graph $G$ means to select, for each edge $e$ of $T$, a corresponding non-tree edge $f$, in such a way that the tree obtained by replacing $e$ with $f$ enjoys some optimality criterion (which is naturally defined according to some objective function originally addressed by $T$). Solving efficiently an ABSE problem is by now a classic algorithmic issue, since it conveys a very successful way of coping with a (transient) \emph{edge failure} in tree-based communication networks: just replace the failing edge with its respective swap edge, so as that the connectivity is promptly reestablished by minimizing the rerouting and set-up costs. In this paper, we solve the ABSE problem for the case in which $T$ is a \emph{single-source shortest-path tree} of $G$, and our two selected swap criteria aim to minimize either the \emph{maximum} or the \emph{average stretch} in the swap tree of all the paths emanating from the source. Having these criteria in mind, the obtained structures can then be reviewed as \emph{edge-fault-tolerant single-source spanners}. For them, we propose two efficient algorithms running in $O(m n +n^2 \log n)$ and $O(m n \log \alpha(m,n))$ time, respectively, and we show that the guaranteed (either maximum or average, respectively) stretch factor is equal to 3, and this is tight. Moreover, for the maximum stretch, we also propose an almost linear $O(m \log \alpha(m,n))$ time algorithm computing a set of \emph{good} swap edges, each of which will guarantee a relative approximation factor on the maximum stretch of $3/2$ (tight) as opposed to that provided by the corresponding BSE. Surprisingly, no previous results were known for these two very natural swap problems.Comment: 15 pages, 4 figures, SIROCCO 201

AFLOW-QHA3P: Robust and automated method to compute thermodynamic properties of solids

Accelerating the calculations of finite-temperature thermodynamic properties is a major challenge for rational materials design. Reliable methods can be quite expensive, limiting their applicability in autonomous high-throughput workflows. Here, the three-phonon quasiharmonic approximation (QHA) method is introduced, requiring only three phonon calculations to obtain a thorough characterization of the material. Leveraging a Taylor expansion of the phonon frequencies around the equilibrium volume, the method efficiently resolves the volumetric thermal expansion coefficient, specific heat at constant pressure, the enthalpy, and bulk modulus. Results from the standard QHA and experiments corroborate the procedure, and additional comparisons are made with the recently developed self-consistent QHA. The three approaches—three-phonon, standard, and self-consistent QHAs—are all included within the open-source ab initio framework aflow, allowing the automated determination of properties with various implementations within the same framework

Genital Chlamydia trachomatis: understanding the roles of innate and adaptive immunity in vaccine research.

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted disease worldwide, and despite significant advances in chlamydial research, a prophylactic vaccine has yet to be developed. This Gram-negative obligate intracellular bacterium, which often causes asymptomatic infection, may cause pelvic inflammatory disease (PID), ectopic pregnancies, scarring of the fallopian tubes, miscarriage, and infertility when left untreated. In the genital tract, Chlamydia trachomatis infects primarily epithelial cells and requires Th1 immunity for optimal clearance. This review first focuses on the immune cells important in a chlamydial infection. Second, we summarize the research and challenges associated with developing a chlamydial vaccine that elicits a protective Th1-mediated immune response without inducing adverse immunopathologies

r-2,c-6-Bis(4-fluoro­phen­yl)-t-3,t-5-dimethyl­piperidin-4-one

In the title compound, C19H19F2NO, the piperidinone ring adopts a chair conformation. The crystal packing is stabilized by C—H⋯O and C—H⋯F inter­molecular inter­actions, generating centrosymmetric dimers of R 2 2(14) and R 2 2(24) rings

3-[(E)-4-Methoxy­benzyl­idene]-1-methyl­piperidin-4-one

The piperidone ring of the title compound, C14H17NO2, adopts a half-chair conformation. The crystal packing is stabilized by inter­molecular C—H⋯O inter­actions, which generate a C(8) chain running along the b axis

3-(4-Methoxy­phen­yl)-6-(phenyl­sulfon­yl)perhydro-1,3-thiazolo[3′,4′:1,2]pyrrolo[4,5-c]pyrrole

In the title compound, C21H24N2O3S2, the three five-membered rings adopt envelope conformations. The dihedral angle between the two aromatic rings is 68.4 (1)°. C—H⋯O inter­actions link the mol­ecules into a chain and the chains are cross-linked via C—H⋯π inter­actions involving the meth­oxy­phenyl ring

3-[(E)-2,4-Dichloro­benzyl­idene]-1-methyl­piperidin-4-one

The piperidine ring of the title compound, C13H13Cl2NO, adopts an envelope conformation. Inter­molecular C—H⋯O inter­actions link the mol­ecules into a C(7) chain running along the b axis

1′-Phenyl-6′-thia­cyclo­heptane-1-spiro-2′-perhydro­pyrrolizine-3′-spiro-3′′-indoline-2,2′′-dione

The thia­zolidine ring and the pyrrolidine ring in the title compound, C25H26N2O2S, both adopt an envelope conformation. The seven-membered ring has a twist-chair conformation. The crystal packing is stabilized by inter­molecular N—H⋯O hydrogen bonds