Commutative combinatorial Hopf algebras

We propose several constructions of commutative or cocommutative Hopf algebras based on various combinatorial structures, and investigate the relations between them. A commutative Hopf algebra of permutations is obtained by a general construction based on graphs, and its non-commutative dual is realized in three different ways, in particular as the Grossman-Larson algebra of heap ordered trees. Extensions to endofunctions, parking functions, set compositions, set partitions, planar binary trees and rooted forests are discussed. Finally, we introduce one-parameter families interpolating between different structures constructed on the same combinatorial objects.Comment: 29 pages, LaTEX; expanded and updated version of math.CO/050245

The Algebra of Binary Search Trees

We introduce a monoid structure on the set of binary search trees, by a process very similar to the construction of the plactic monoid, the Robinson-Schensted insertion being replaced by the binary search tree insertion. This leads to a new construction of the algebra of Planar Binary Trees of Loday-Ronco, defining it in the same way as Non-Commutative Symmetric Functions and Free Symmetric Functions. We briefly explain how the main known properties of the Loday-Ronco algebra can be described and proved with this combinatorial point of view, and then discuss it from a representation theoretical point of view, which in turns leads to new combinatorial properties of binary trees.Comment: 49 page

External Benefits of Irrigation in Mountain Areas: Stakeholder Perceptions and Water Policy Implications

Irrigation contributes to land and ecosystem degradation, especially in intensive farming areas. However, in marginal areas, long-established irrigation systems also supply agroecosystem services. This study aimed to identify and prioritize the external benefits provided by irrigation in extensive grazing farms in an Italian alpine region (Aosta Valley, NW Italy). Three local stakeholder groups (land irrigation consortia members, non-farmer users of the irrigation water service, and non-user citizens) engaged in focus group discussions. The transcriptions were analyzed with an integrated subjective and computer-assisted approach. The main result of the study showed that a convergence of stakeholder opinions led to prioritization of the same four benefits, i.e., hydro-geological and land maintenance, traditional agricultural landscape conservation, biodiversity conservation, and leisure recreational activities provision. Incorporating this information into decision-making processes is relevant in marginal mountain areas, especially in light of the implementation of the water pricing policy laid down in the EU Water Framework Directive. To this end, the economic value of the external benefits should be considered along with the recovery costs for water services. Such information is essential to balance the environmental costs of irrigation and to compare the resource cost of alternative water uses

Novel insights into cochlear information processing

Already Helmholtz profoundly addressed the question how the nonlinearity of the human hearing sensor, the cochlea, might shape human sound perception. At his time, research was, however, obstructed by the lack of experimental data regarding the amplification properties of the inner ear. In the meantime, accurate measuring methods have permitted the comparison of models of the hearing sensor with empirical data, leading to a strong revival of the interest into Helmholtz’s original research questions. In our paper, we describe some recent theoretical and modeling advances in the understanding of the nature of human pitch perception. We reveal a number of to date unexplained human auditory percept effects to be direct consequences of the nonlinear properties of the mammalian hearing sensor. Our insights also demonstrate, as a by-note, the limitations of the present reverse engineering approach towards cochlear implants

Conservare l’eredità di Vittone tra conoscenza storica e progetto di restauro

Da una rilettura della storiografia vittoniana emerge la rilevanza della figura di Eugenio Olivero, primo esponente, fra gli studiosi di inizio del XX secolo, a cui si deve il riconoscimento di aver documentato e studiato le architetture di Vittone con passione e curiosità tecnica, ispirando un approccio integrato tra storia e analisi dell’architettura, dei magisteri edilizi e delle tecniche costruttive. Attraverso un esame dell’archivio dell’ studioso, conservato all’Accademia delle Scienze di Torino, il saggio considera l’eredità di Olivero come utile chiave di lettura sia per riflettere sulla carriera e opera di Vittone, sia per ripercorrere le origini di una storia della conservazione dei suoi edifici. Oggi, consolidato l’orientamento metodologico fatto proprio dallo studioso, quale fase propedeutica alla redazione del progetto di restauro, resta aperto il tema della conservazione della autorialità delle architetture vittoniane, individuando in una maggiore interoperabilità dei dati raccolti negli interventi di restauro già eseguiti, la strada per una conservazione e valorizzazione consapevole e coerente, oltre che condivisa, di questo patrimonio

Safety of polymyxin-B-based hemoperfusion in kidney and liver transplant recipients.

Abstract Infection represents one of the primary barriers to successful organ transplantation. Our principal end point was to use a new assay, Entotoxin Activity Assay (EAA), which was developed to rapidly detect endotoxin activity (EA) for an early diagnosis of this complication. We also sought to prove the validity and safety of endotoxin removal using polymyxin-B–based hemoperfusion (PMX-DHP). The criterion for inclusion in the study was suspected infection when a patient experienced at least 2 of the 4 criteria of the systemic inflammatory response syndrome. EAA was performed on 71 patients: 29 liver transplantations and 42 kidney transplantations. Twenty-eight patients (39.5%) with EA >0.60 underwent PMX-DHP treatment to remove endotoxins. Each treatment was performed for 2 hours with a blood flow of 100 mL/min. All of the patients were treated with PMX-DHP until achieving an E

High performance liquid chromatographic determination of 2-furaldehyde and 5-hydroxymethyl-2-furaldehyde in processes citrus juices

The occurrence of 2-furaldehyde (F) and 5-hydroxymethyl-2-furaldehyde (HMF) in processed citrus juices is an indication of quality deterioration. A close relationship between flavor changes and F content exists, while HMF can give rise to browning reactions. Both F and HMF are formed during heat processing or storage at improper temperatures. The detection of these compounds becomes more and more important as aseptic processing and packaging of citrus juices are becoming widespread. Aseptic packaging allows higher temperatures during distribution and storage to be employed without microbial spoilage, but off-flavors develop as citrus products are exposed to these conditions. In this paper a method of determination by high performance liquid chromatography (HPLC) is described. The method is based on the formation of the 2,4-dinitrophenylhydrazones of carbonyl compounds and subsequent reversed-phase separation of these derivatives. Derivatization is carried out by utilizing an acidic solution of 2,4-dinitrophenylhydrazine in acetonitrile. Precipitation of the derivatives of carbonyl compounds is thus avoided, and direct injection of the sample into the HPLC system is allowed. The determination offers a high specificity and a detection limit of the order of 10-8 mol/l for both analytes. Recoveries from an orange juice spiked at different levels are quantitative. Reproducibility data are presented