Criticality of O(N) symmetric models in the presence of discrete gauge symmetries

We investigate the critical properties of the three-dimensional (3D) antiferromagnetic RP(N-1}) model, which is characterized by a global O(N) symmetry and a discrete Z_2 gauge symmetry. We perform a field-theoretical analysis using the Landau-Ginzburg-Wilson (LGW) approach and a numerical Monte Carlo study. The LGW field-theoretical results are obtained by high-order perturbative analyses of the renormalization-group (RG) flow of the most general Phi^4 theory with the same global symmetry as the model, assuming a gauge-invariant order-parameter field. For N=4 no stable fixed point is found, implying that any transition must necessarily be of first order. This is contradicted by the numerical results that provide strong evidence for a continuous transition. This suggests that gauge modes are not always irrelevant, as assumed by the LGW approach, but they may play an important role to determine the actual critical dynamics at the phase transition of O(N) symmetric models with a discrete Z_2 gauge symmetry.Comment: 12 pages. arXiv admin note: text overlap with arXiv:1502.07599, arXiv:1706.0436

Landau-Ginzburg-Wilson approach to critical phenomena in the presence of gauge symmetries

We critically reconsider the Landau-Ginzburg-Wilson (LGW) approach to critical phenomena in the presence of gauge symmetries. In the LGW framework, to obtain the universal features of a continuous transition, one identifies the order parameter Phi and considers the corresponding most general Phi4 field theory that has the same symmetries as the original model. In the presence of gauge symmetries, one usually considers a gauge-invariant order parameter and a LGW field theory that is invariant under the global symmetries of the original model. We show that this approach, in which the gauge dynamics is effectively integrated out, may sometimes lead to erroneous conclusions on the nature of the critical behavior. As an explicit example, we show that the above-described LGW approach generally fails for the three-dimensional ferromagnetic and antiferromagnetic CP(N-1) models, which are invariant under global U(N) and local U(1) transformations. We point out possible implications for the finite-temperature chiral transition of nuclear matter.Comment: 7 pages, few changes, refs adde

How I diagnose and treat splenic lymphomas.

The incidental finding of an isolated splenomegaly during clinical assessment of patients evaluated for unrelated causes has become increasingly frequent because of the widespread use of imaging. Therefore, the challenging approach to the differential diagnosis of spleen disorders has emerged as a rather common issue of clinical practice. A true diagnostic dilemma hides in distinguishing pathologic conditions primarily involving the spleen from those in which splenomegaly presents as an epiphenomenon of hepatic or systemic diseases. Among the causes of isolated splenomegaly, lymphoid malignancies account for a relevant, yet probably underestimated, number of cases. Splenic lymphomas constitute a wide and heterogeneous array of diseases, whose clinical behavior spans from indolent to highly aggressive. Such a clinical heterogeneity is paralleled by the high degree of biologic variation in the lymphoid populations from which they originate. Nevertheless, the presenting clinical, laboratory, and pathologic features of these diseases often display significant overlaps. In this manuscript, we present our approach to the diagnosis and treatment of these rare lymphomas, whose complexity has been so far determined by the lack of prospectively validated prognostic systems, treatment strategies, and response criteria

Torre in C2. Osservazioni su un laboratorio di progettazione architettonica

A partire dall'osservazione di un'esperienza didattica in un laboratorio di progettazione architettonica, si riflette su un metodo di insegnamento che pone l'architettura fra la realtà urbana e la storia, in una prospettiva di acquisizione di strumenti necessari all'elaborazione progettuale. I cicli dei laboratori "Torre in C2" chiudono l'attività didattica pluriennale di Giuliana Tripodo. Si cerca di rintracciare le matrici formative di questa esperienza in un dialogo che travalica i recinti disciplinari

A tribute to Juan Rosai

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A Quarterly Food-at-Home Price Database for the U.S.

This report provides a detailed description of the methodology used to construct ERS’s Quarterly Food-at-Home Price Database (Q-FAHPD). As the name suggest, these data provide quarterly observations on the mean price of 52 food categories for specific U.S. markets. We provide a description of the Nielsen Homescan data that was used to create this database, the methodology used to classify foods into food groups, how we determined the appropriate the level of aggregation (sub-regional markets) and our calculation of average prices for each food group. This report also contains an overview and summary of the resulting data.Nielsen Homescan, food prices, diet quality, market prices, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Health Economics and Policy,

Design of semi-interpenetrating networks based on poly(ethyl-2-cyanoacrylate) and oligo(ethylene glycol) diglycidyl ether

The synthesis of semi-interpenetrating networks (SIPN) based on linear poly(ethyl 2- cyanoacrylate) (PECA) and oligo(ethylene glycol) diglycidyl ether (OEGDG) based polymer networks was motivated by the hypothesis that the brittleness of polycyanoacrylates may be overcome by incorporating them into a polymer network architecture. A sequential synthetic route was applied, in which first PECA was prepared by anionic polymerization. Subsequently, OEGDG was crosslinked with different anhydrides and curing catalysts to form networks with hydrolyzable ester bonds and interpenetrating PECA. These SIPNs showed a low water uptake compared to other polyether based networks. Some of the obtained materials were transparent and exhibited a great flexibility, which was maintained also after 24 h of immersion in water and subsequent drying. Such networks could be components of future stimuli-sensitive material systems