On totally geodesic submanifolds in the Jacobian locus

We study submanifolds of A_g that are totally geodesic for the locally symmetric metric and which are contained in the closure of the Jacobian locus but not in its boundary. In the first section we recall a formula for the second fundamental form of the period map due to Pirola, Tortora and the first author. We show that this result can be stated quite neatly using a line bundle over the product of the curve with itself. We give an upper bound for the dimension of a germ of a totally geodesic submanifold passing through [C] in M_g in terms of the gonality of C. This yields an upper bound for the dimension of a germ of a totally geodesic submanifold contained in the Jacobian locus, which only depends on the genus. We also study the submanifolds of A_g obtained from cyclic covers of the projective line. These have been studied by various authors. Moonen determined which of them are Shimura varieties using deep results in positive characteristic. Using our methods we show that many of the submanifolds which are not Shimura varieties are not even totally geodesic.Comment: To appear on International Journal of Mathematic

Metabolic interactions between vitamin A and conjugated linoleic acid

Lipid-soluble molecules share several aspects of their physiology due to their common adaptations to a hydrophilic environment, and may interact to regulate their action in a tissue-specific manner. Dietary conjugated linoleic acid (CLA) is a fatty acid with a conjugated diene structure that is found in low concentrations in ruminant products and available as a nutritional supplement. CLA has been shown to increase tissue levels of retinol (vitamin A alcohol) and its sole specific circulating carrier protein retinol-binding protein (RBP or RBP4). However, the precise mechanism of this action has not been elucidated yet. Here, we provide a summary of the current knowledge in this specific area of research and speculate that retinol and CLA may compete for catabolic pathways modulated by the activity of PPAR- and RXR heterodimer. We also present preliminary data that may position PPAR- at the crossroads between the metabolism of lipids and vitamin

Minor millets as a central element for sustainably enhanced incomes, empowerment, and nutrition in rural India

Minor millets comprise a group of cereal species that are genetically diverse and adapted to a range of marginal growing conditions where major cereals such as wheat, rice, and maize are relatively unsuccessful. Millets require few inputs and withstand severe biotic and abiotic stresses. They are also more nutritious than major cereals. Despite these advantages, neglect in several arenas has resulted in a steady decline in the cultivation of minor millets in India over the past few decades. As part of a United Nations global project on underutilized species, we undertook action research intended to stem the decline in cultivation and enhance the conservation and use of minor millets in 753 households spread across 34 villages in four states of India. Our aim was to improve incomes, nutritional status, and empowerment, especially for women. Overall, our holistic approach to mainstreaming species such as finger millet, little millet, foxtail millet, and barnyard millet indicates that these neglected and underutilized species can play a strategic role in improving many dimensions of livelihoods

Identification and Calculation of the Universal Maximum Drag Reduction Asymptote by Polymers in Wall Bounded Turbulence

Drag reduction by polymers in wall turbulence is bounded from above by a universal maximal drag reduction (MDR) velocity profile that is a log-law, estimated experimentally by Virk as $V^+(y^+)\approx 11.7 \log y^+ -17$. Here $V^+(y)$ and $y^+$ are the mean streamwise velocity and the distance from the wall in "wall" units. In this Letter we propose that this MDR profile is an edge solution of the Navier-Stokes equations (with an effective viscosity profile) beyond which no turbulent solutions exist. This insight rationalizes the universality of the MDR and provides a maximum principle which allows an ab-initio calculation of the parameters in this law without any viscoelastic experimental input.Comment: 4 pages, 1 fig. Phys. Rev. Letts., submitte

Phase transitions for the cavity approach to the clique problem on random graphs

We give a rigorous proof of two phase transitions for a disordered system designed to find large cliques inside Erdos random graphs. Such a system is associated with a conservative probabilistic cellular automaton inspired by the cavity method originally introduced in spin glass theory.Comment: 36 pages, 4 figure

Small interfering RNA-producing loci in the ancient parasitic eukaryote Trypanosoma brucei

BACKGROUND: At the core of the RNA interference (RNAi) pathway in Trypanosoma brucei is a single Argonaute protein, TbAGO1, with an established role in controlling retroposon and repeat transcripts. Recent evidence from higher eukaryotes suggests that a variety of genomic sequences with the potential to produce double-stranded RNA are sources for small interfering RNAs (siRNAs). RESULTS: To test whether such endogenous siRNAs are present in T. brucei and to probe the individual role of the two Dicer-like enzymes, we affinity purified TbAGO1 from wild-type procyclic trypanosomes, as well as from cells deficient in the cytoplasmic (TbDCL1) or nuclear (TbDCL2) Dicer, and subjected the bound RNAs to Illumina high-throughput sequencing. In wild-type cells the majority of reads originated from two classes of retroposons. We also considerably expanded the repertoire of trypanosome siRNAs to encompass a family of 147-bp satellite-like repeats, many of the regions where RNA polymerase II transcription converges, large inverted repeats and two pseudogenes. Production of these newly described siRNAs is strictly dependent on the nuclear DCL2. Notably, our data indicate that putative centromeric regions, excluding the CIR147 repeats, are not a significant source for endogenous siRNAs. CONCLUSIONS: Our data suggest that endogenous RNAi targets may be as evolutionarily old as the mechanism itself

VLBI observations of nearby radio loud Active Galactic Nuclei

We present an update of the parsec scale properties of the Bologna Complete Sample consisting of 95 radio sources from the B2 Catalog of Radio Sources and the Third Cambridge Revised Catalog (3CR), with z < 0.1. Thanks to recent new data we have now parsec scale images for 76 sources of the sample. Most of them show a one-sided jet structure but we find a higher fraction of two-sided sources in comparison with previous flux-limited VLBI surveys. A few peculiar sources are presented and discussed in more detail.Comment: 6 pages, 7 figures, Proceedings for "The Universe under the Microscope" (AHAR 2008), April 2008, to be published in Journal of Physics: Conference Series by Institute of Physics Publishing; R. Schoedel, A. Eckart, S. Pfalzner, and E. Ros ed

Cracking the laugh code: laughter through the lens of biology, psychology and neuroscience

Preface to the theme issue which tackles the biological, psychological, neural, and cultural underpinnings of laughter in humans and other animals from a naturalistic and evolutionary perspective

Optimization of extraction of drugs containing polyphenols using an innovative technique

The role of polyphenols in human health nowadays is well established and these natural products, found in many plant species, are the active ingredients of drugs, food supplements and cosmetics. Extraction procedure is pivotal to obtain high quality herbal products but paradoxically this factor is often underrated and obsolete techniques are used. In this work we compared the classic and most used method of maceration and an innovative and standardized technique of extraction, Estrattore Naviglio((R)), processing ten common medicinal plants containing polyphenols and for each analysing specific biological markers such as flavonoids, anthocyanosides and caffeic derivatives in addition to total polyphenols content. Estrattore Naviglio((R)) guaranteed a significant improvement of the chemical quality of extracts combining effectiveness with rapidity and reproducibility. In this work we further investigated the optimization of drug extractions by replicating operations varying parameters setting on Estrattore Naviglio((R)) instrument