Branched covers of the sphere and the prime-degree conjecture

To a branched cover between closed, connected and orientable surfaces one associates a "branch datum", which consists of the two surfaces, the total degree d, and the partitions of d given by the collections of local degrees over the branching points. This datum must satisfy the Riemann-Hurwitz formula. A "candidate surface cover" is an abstract branch datum, a priori not coming from a branched cover, but satisfying the Riemann-Hurwitz formula. The old Hurwitz problem asks which candidate surface covers are realizable by branched covers. It is now known that all candidate covers are realizable when the candidate covered surface has positive genus, but not all are when it is the 2-sphere. However a long-standing conjecture asserts that candidate covers with prime degree are realizable. To a candidate surface cover one can associate one Y -> X between 2-orbifolds, and in a previous paper we have completely analyzed the candidate surface covers such that either X is bad, spherical, or Euclidean, or both X and Y are rigid hyperbolic orbifolds, thus also providing strong supporting evidence for the prime-degree conjecture. In this paper, using a variety of different techniques, we continue this analysis, carrying it out completely for the case where X is hyperbolic and rigid and Y has a 2-dimensional Teichmueller space. We find many more realizable and non-realizable candidate covers, providing more support for the prime-degree conjecture

New gene functions are involved in the thermotolerance of the wild wheat relative Aegilops umbellulata

Wheat is one of the most important food crops in the world for human consumption, like all plants it is exposed to environmental stresses including high temperatures. The deleterious effect of high temperatures negatively affects plant growth and development, leading to reduced viability and yield. These effects can be reduced by improvement of thermotolerance through innovative breeding strategies, based on the expansion of the genetic pool available, by exploring important genetic functions from wheat wild progenitors. Improving the genetic thermotolerance characteristics of wheat requires greater understanding of genetic bases of thermotolerance, through identification of high temperature stress related genes. A good source of new useful alleles is given by Aegilops species characterized by thermotolerant habits. In this study we have classified as thermotolerant or thermosensitive, on the basis of physiologic tests, some accessions of wheat wild relative species belonging to Aegilops and Triticum genera. A thermotolerant accession of Aegilops umbellulata (AUM5) was selected, subjected to different thermal treatments and analyzed at transcriptional level. By differential display reverse transcriptase polymerase chain reaction (DDRT-PCR), we investigated modulation of gene expression elicited by heat treatments. This approach allowed the identification of various transcript-derived fragments (TDFs) produced by AUM5 in response to different thermal treatments. The functions of the inducible unique genes in the molecular determination of thermotolerance process are discussed

Is old stuff back? A fatal case of ethyl chloride sniffing

Background: Ethyl chloride (EC) or chloroethane is a colourless halogenated hydrocarbon gas regularly employed as a topical anaesthetic spray for pain-related injuries and muscle spasm in athletes. However, EC became also popular as a street drug in the 1980s. Brief inhalations of EC vapour can result in dizziness, euphoria, confusion, incoordination, hallucinosis, impairment of short-term memory and narcosis. Inhalation of higher doses, usually employed to \u201cget high\u201d, may be related to severe depression of the central nervous system. Indeed, toxicity and deaths have been reported so far. Case presentation: A 40-year-old man was found unresponsive after EC inhalation. EC determination was performed by dynamic headspace gas chromatography coupled to mass spectrometry. EC was detected in the peripheral blood (0.156 g/L), central blood concentration (0.203 g/L) and the lung and brain (19 and 25 mg/kg). EC in the vitreous humour showed a sensitively lower respect to blood (0.018 vs 0.203 g/L). Conclusions: Considering the results of toxicological analyses of investigations on the death scene besides the absence of any signs of trauma, death was attributed to inhalation of ethyl chloride

Il problema del rimbalzo unidimensionale

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Problema dell'unicità. - Esempio di non unicità

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Il problema del rimbalzo unidimensionale

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Il problema del rimbalzo unidimensionale e sue approssimazioni non convesse

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Problema dell'unicità. - Esempio di non unicità

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Approssimazioni con penalizzazioni non convesse per il pdr unidimensionale e teorema di esistenza

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Problema dell'unicità. - Esempio di non unicità

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