The Algebra of Non-Local Charges in Non-Linear Sigma Models

We obtain the exact Dirac algebra obeyed by the conserved non-local charges in bosonic non-linear sigma models. Part of the computation is specialized for a symmetry group $O(N)$. As it turns out the algebra corresponds to a cubic deformation of the Kac-Moody algebra. The non-linear terms are computed in closed form. In each Dirac bracket we only find highest order terms (as explained in the paper), defining a saturated algebra. We generalize the results for the presence of a Wess-Zumino term. The algebra is very similar to the previous one, containing now a calculable correction of order one unit lower.Comment: 27 pages + figures available via ftp, Plain TeX, IFUSP/P-106

Sviluppo di un acciaio per lavorazione a caldo rinforzato tramite alligazione meccanica

I compositi a matrice metallica combinano elevata durezza e buona tenacità offrendo la possibilità di modularele loro proprietà attraverso la scelta più opportuna del tipo, frazione e dimensioni del rinforzo. La produzione dicompositi a matrice metallica basati su acciai per lavorazioni a caldo è stata poco sviluppata in letteratura. Inquesto lavoro è stata investigata la possibilità di produrre un acciaio per lavorazioni a caldo AISI H13 rinforzatocon particelle ceramiche di diversa natura quali carburi (TiC), nitruri (TiN) e boruri (TiB2). Questi compostirisultano particolarmente promettenti per applicazioni ad alta temperatura data la loro elevata stabilità termica.Le polveri composite sono state prodotte tramite macinazione meccanica, ottenendo un affinamento dellamicrostruttura e una fine distribuzione delle particelle di rinforzo. Le polveri composite sono state sinterizzatetramite la tecnica Spark Plasma, in modo da preservare la fine microstruttura prodotta durante macinazionee limitare l’interazione tra matrice e particelle rinforzanti. Il composito con il 20%vol di TiB2 mostra la migliordensificazione raggiungendo quasi densità teorica. L’analisi diffrattometrica ai raggi-x di questo materialeevidenzia però la formazione di composti secondari, quali Fe2B e TiC, indicando una parziale decomposizione delTiB2. Tra i materiali sinterizzati, il composito il TiC mostra il maggior incremento di durezza

SPS-assisted Synthesis of SICp reinforced high entropy alloys: reactivity of SIC and effects of pre-mechanical alloying and post-annealing treatment

In this work a traditional high entropy alloy (FeCoNiCrAl) was reinforced by uniformly distributed reactive silicon carbide (SiC) particles by a powder metallurgy synthetic route, using as precursors simply mixed powders or mechanically prealloyed ones. The reactive sintering produced a single isomorphic BCC structure. The sample microstructure resulted equiassic, more homogenous in samples based on prealloyed powders. The instability of SiC in the presence of metal precursors resulted in the formation of more stable carbides and silicides, as well as in carbon diffusion in the high entropy alloy matrix and partially unreacted SiC particles. The formation of these newly formed fine precipitates, as well as the presence of residual SiC were useful to increase the hardness of the alloy

High entropy alloys obtained by field assisted powder metallurgy route: SPS and microwave heating

The aim of this work was to investigate the field assisted powder metallurgy route for producing HEAs at equimolar composition, i.e. FeCoNiCrAl, starting from metal powders. Both mixed, mechanically activated and mechanically alloyed powders have been used. The powders obtained by mechanical alloying were synthesized only by SPS, whereas the remaining ones were sintered by SPS or microwave heating. The investigated field assisted sintering techniques allowed an extremely short alloying time, high energy density on the load and negligible contamination by the surrounding environment. Both the conducted sintering-synthesis technology resulted not definitive to produce chemical homogeneity and to obtain a single stable structure. Thus a subsequently heat treatment was required. The post heat treatment, indeed, led to a single crystalline structure (FCC) and the material was fully recrystallized. After heat treatment samples are isomorphic: they exhibit two different phases with the same FCC cell, but different chemical composition, in detail Fe-Cr richer and Al-Ni richer. SPS-ed samples present a reduced porosity, while microwave processed ones are much more porous and this is reflected in the mechanical properties

Studio del processo di macinazione meccanica di un acciaio per lavorazioni a caldo

Gli acciai per lavorazioni a caldo sono caratterizzati da buona tenacità ed elevata durezza a caldo.La metallurgia delle polveri, grazie alla produzione di materiali con microstruttura più fine,consente di migliorare entrambe queste caratteristiche. In questo lavoro, una polvere di AISI H13atomizzata in gas è stata macinata meccanicamente in modo da ridurre sia la dimensione delleparticelle che la dimensione della grana cristallina. I risultati mostrano che dopo 1000 minuti dimacinazione in un mulino planetario a sfere la dimensione del grano può essere ridotta in modosignificativo fino a 15nm. L’elevato grado di deformazione introdotto nelle particelle attiva ilprocesso di sinterizzazione e di conseguenza la polvere può essere sinterizzata a temperature e pertempi inferiori. Per produrre campioni ad alta densità e per mantenere la dimensione della granafine (<1?m) la polvere è stata sinterizzata tramite Spark Plasma Sintering. La microstruttura e ladurezza dei campioni prodotti da polvere macinata sono state investigate e confrontate con quelle diun materiale prodotto con polvere atomizzata

Análise faunística de cochonilhas (hemiptera: sternorrhyncha) na cultura da videira no município de Pinto Bandeira, Rio Grande do Sul, Brasil.

O Rio Grande do Sul é o principal estado produtor de uvas e vinhos do país, com destaque para a região da Serra Gaúcha. Um dos principais problemas enfrentados pelos viticultores é a presença de cochonilhas que ocorrem na parte aérea da cultura e que, dependendo da severidade dos danos causam a morte da planta. Nesse trabalho foi realizada uma análise faunística das cochonilhas presentes na parte aérea de videiras, no município de Pinto Bandeira, RS. As amostragens foram realizadas quinzenalmente em vinhedo comercial de 1 ha de Vitis vinifera L. cultivar Merlot. Foram coletadas amostras de cochonilhas presentes no ritidoma e brotações, de janeiro de 2011 a janeiro de 2013. A triagem e identificação dos espécimes foram realizadas em laboratório com o auxílio de microscópio óptico e bibliografia especializada. Os dados obtidos foram analisados a partir da determinação da frequência, constância e dominância. Foram identificadas duas espécies de cochonilhas incluídas em Diaspididae - Hemiberlesia latanie e Pseudaonidia marquesi; e uma em Monophlebidae - Icerya schrottkyi. Hemiberlesia latanie foi a espécie que apresentou 89,72% de frequência, I. schrottkyi 7,13% e P. marquesi 3,14%. Hemiberlesia latanie foi a cochonilha dominante, mais frequente e constante no vinhedo

Sexual reproduction and mating-type-mediated strain development in the penicillin-producing fungus Penicillium chrysogenum

Penicillium chrysogenum is a filamentous fungus of major medical and historical importance, being the original and present-day industrial source of the antibiotic penicillin. The species has been considered asexual for more than 100 y, and despite concerted efforts, it has not been possible to induce sexual reproduction, which has prevented sexual crosses being used for strain improvement. However, using knowledge of mating-type (MAT) gene organization, we now describe conditions under which a sexual cycle can be induced leading to production of meiotic ascospores. Evidence of recombination was obtained using both molecular and phenotypic markers. The identified heterothallic sexual cycle was used for strain development purposes, generating offspring with novel combinations of traits relevant to penicillin production. Furthermore, the MAT1-1–1 mating-type gene, known primarily for a role in governing sexual identity, was also found to control transcription of a wide range of genes with biotechnological relevance including those regulating penicillin production, hyphal morphology, and conidial formation. These discoveries of a sexual cycle and MAT gene function are likely to be of broad relevance for manipulation of other asexual fungi of economic importance

AKT1 and MYC Induce Distinctive Metabolic Fingerprints in Human Prostate Cancer

Cancer cells may overcome growth factor dependence by deregulating oncogenic and/or tumor-suppressor pathways that affect their metabolism, or by activating metabolic pathways de novo with targeted mutations in critical metabolic enzymes. It is unknown whether human prostate tumors develop a similar metabolic response to different oncogenic drivers or a particular oncogenic event results in its own metabolic reprogramming. Akt and Myc are arguably the most prevalent driving oncogenes in prostate cancer. Mass spectrometry–based metabolite profiling was performed on immortalized human prostate epithelial cells transformed by AKT1 or MYC, transgenic mice driven by the same oncogenes under the control of a prostate-specific promoter, and human prostate specimens characterized for the expression and activation of these oncoproteins. Integrative analysis of these metabolomic datasets revealed that AKT1 activation was associated with accumulation of aerobic glycolysis metabolites, whereas MYC overexpression was associated with dysregulated lipid metabolism. Selected metabolites that differentially accumulated in the MYC-high versus AKT1-high tumors, or in normal versus tumor prostate tissue by untargeted metabolomics, were validated using absolute quantitation assays. Importantly, the AKT1/MYC status was independent of Gleason grade and pathologic staging. Our findings show how prostate tumors undergo a metabolic reprogramming that reflects their molecular phenotypes, with implications for the development of metabolic diagnostics and targeted therapeutics.Fil: Priolo, Carmen. Department of Medical Oncology. Dana Farber Cancer Institute. Brigham and Women's Hospital; Estados UnidosFil: Pyne, Saumyadipta. Department of Medical Oncology. Dana Farber Cancer Institute. Brigham and Women's Hospital; Estados UnidosFil: Rose, Joshua. Department of Medical Oncology. Dana Farber Cancer Institute. Brigham and Women's Hospital; Estados UnidosFil: Regan, Erzsébet Ravasz. Harvard Medical School; Estados UnidosFil: Zadra, Giorgia. Department of Medical Oncology. Dana Farber Cancer Institute. Brigham and Women's Hospital; Estados UnidosFil: Photopoulos, Cornelia. Department of Medical Oncology. Dana Farber Cancer Institute. Brigham and Women's Hospital; Estados UnidosFil: Cacciatore, Stefano. Department of Medical Oncology. Dana Farber Cancer Institute. Brigham and Women's Hospital; Estados UnidosFil: Schultz, Denise. Johns Hopkins University; Estados UnidosFil: Scaglia, Natalia. Department of Medical Oncology. Dana Farber Cancer Institute. Brigham and Women's Hospital; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: McDunn, Jonathan. Metabolon Inc.; Estados UnidosFil: de Marzo, Angelo M.. Johns Hopkins University; Estados UnidosFil: Loda, Massimo. Department of Pathology. Brigham and Women's Hospital; Estados Unidos. Department of Medical Oncology. Dana Farber Cancer Institute. Brigham and Women's Hospital; Estados Unidos. University of Cambridge; Estados Unidos. King's College London. Division of Cancer Studies; Estados Unido

On a Testing Methodology for the Mechanical Property Assessment of a New Low-Cost Titanium Alloy Derived from Synthetic Rutile

Mechanical property data of a low-cost titanium alloy derived directly from synthetic rutile is reported. A small-scale testing approach comprising consolidation via field-assisted sintering technology, followed by axisymmetric compression testing, has been designed to yield mechanical property data from small quantities of titanium alloy powder. To validate this approach and provide a benchmark, Ti-6Al-4V powder has been processed using the same methodology and compared with material property data generated from thermo-physical simulation software. Compressive yield strength and strain to failure of the synthetic rutile-derived titanium alloy were revealed to be similar to that of Ti-6Al-4V