A heterotic sigma model with novel target geometry

We construct a (1,2) heterotic sigma model whose target space geometry consists of a transitive Lie algebroid with complex structure on a Kaehler manifold. We show that, under certain geometrical and topological conditions, there are two distinguished topological half--twists of the heterotic sigma model leading to A and B type half--topological models. Each of these models is characterized by the usual topological BRST operator, stemming from the heterotic (0,2) supersymmetry, and a second BRST operator anticommuting with the former, originating from the (1,0) supersymmetry. These BRST operators combined in a certain way provide each half--topological model with two inequivalent BRST structures and, correspondingly, two distinct perturbative chiral algebras and chiral rings. The latter are studied in detail and characterized geometrically in terms of Lie algebroid cohomology in the quasiclassical limit.Comment: 83 pages, no figures, 2 references adde

Characterising epithelial tissues using persistent entropy

In this paper, we apply persistent entropy, a novel topological statistic, for characterization of images of epithelial tissues. We have found out that persistent entropy is able to summarize topological and geometric information encoded by \alpha-complexes and persistent homology. After using some statistical tests, we can guarantee the existence of significant differences in the studied tissues.Comment: 12 pages, 7 figures, 4 table

Insights Into Aboriginal Australian Mortuary Practices: Perspectives From Ancient DNA

Paleogenetics is a relatively new and promising field that has the potential to provide new information about past Indigenous social systems, including insights into the complexity of burial practices. We present results of the first ancient DNA (aDNA) investigation into traditional mortuary practices among Australian Aboriginal people with a focus on North-East Australia. We recovered mitochondrial and Y chromosome sequences from five ancestral Aboriginal Australian remains that were excavated from the Flinders Island group in Cape York, Queensland. Two of these individuals were sampled from disturbed beach burials, while the other three were from bundle burials located in rock shelters. Genomic analyses showed that individuals from all three rock shelter burials and one of the two beach burials had a close genealogical relationship to contemporary individuals from communities from Cape York. In contrast the remaining male individual, found buried on the beach, had a mitochondrial DNA sequence that suggested that he was not from this location but that he was closely related to people from central Queensland or New South Wales. In addition, this individual was associated with a distinctive burial practice to the other four people. It has been suggested that traditionally non-locals or lower status individuals were buried on beaches. Our findings suggest that theories put forward about beach burials being non-local, or less esteemed members of the community, can potentially be resolved through analyses of uniparental genomic data. Generally, these results support the suggestion often derived from ethnohistoric accounts that inequality in Indigenous Australian mortuary practices might be based on the status, sex, and/or age of individuals and may instead relate to place of geographic origin. There is, however, some departure from the traditional ethnohistoric account in that complex mortuary internments were also offered to female individuals of the community, with genomic analyses helping to confirm that the gender of one of the rockshelter internments was that of a young female

Symmetry and Specializability in the continued fraction expansions of some infinite products

Let $f(x) \in \mathbb{Z}[x]$. Set $f_{0}(x) = x$ and, for $n \geq 1$, define $f_{n}(x)$ $=$ $f(f_{n-1}(x))$. We describe several infinite families of polynomials for which the infinite product \prod_{n=0}^{\infty} (1 + \frac{1}{f_{n}(x)}) has a \emph{specializable} continued fraction expansion of the form S_{\infty} = [1;a_{1}(x), a_{2}(x), a_{3}(x), ... ], where $a_{i}(x) \in \mathbb{Z}[x]$, for $i \geq 1$. When the infinite product and the continued fraction are \emph{specialized} by letting $x$ take integral values, we get infinite classes of real numbers whose regular continued fraction expansion is predictable. We also show that, under some simple conditions, all the real numbers produced by this specialization are transcendental.Comment: 24 page

Scientific questions for the exploration of the terrestrial planets and Jupiter - Advanced planetary missions technology program Progress report

Scientific questions and experimental design for planetary exploration of Jupiter, Mars, Mercury, and Venu

Endothelial Jagged1 promotes solid tumor growth through both pro-angiogenic and angiocrine functions

Angiogenesis is an essential process required for tumor growth and progression. The Notch signaling pathway has been identified as a key regulator of the neo-angiogenic process. Jagged-1 (Jag1) is a Notch ligand required for embryonic and retinal vascular development, which direct contribution to the regulation of tumor angiogenesis remains to be fully characterized. The current study addresses the role of endothelial Jagged1-mediated Notch signaling in the context of tumoral angiogenesis in two different mouse tumor models: subcutaneous Lewis Lung Carcinoma (LLC) tumor transplants and the autochthonous Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP). The role of endothelial Jagged1 in tumor growth and neo-angiogenesis was investigated with endothelial-specific Jag1 gain- and loss-of-function mouse mutants (eJag1OE and eJag1cKO). By modulating levels of endothelial Jag1, we observed that this ligand regulates tumor vessel density, branching, and perivascular maturation, thus affecting tumor vascular perfusion. The pro-angiogenic function is exerted by its ability to positively regulate levels of Vegfr-2 while negatively regulating Vegfr-1. Additionally, endothelial Jagged1 appears to exert an angiocrine function possibly by activating Notch3/Hey1 in tumor cells, promoting proliferation, survival and epithelial-to-mesenchymal transition (EMT), potentiating tumor development. These findings provide valuable mechanistic insights into the role of endothelial Jagged1 in promoting solid tumor development and support the notion that it may constitute a promising target for cancer therapy

A unitary model for structure functions and diffractive production at small x

We propose a unified approach which describes both structure functions in the small-$x$ region and diffractive production in $\gamma^*p$-interactions. It is shown that the model, based on reggeon calculus and a quark-parton picture of the interaction, gives a good description of available experimental data in a broad region of $Q^2$ (including $Q^2 =0$) with a single Pomeron of intercept $\alpha_P(0) = 1.2$. Predictions for very small $x$ are given and the problem of saturation of parton densities is discussed.Comment: 43 pages, latex, 15 postscript figure

Probing the formation of intermediate- to high-mass stars in protoclusters II. Comparison between millimeter interferometric observations of NGC 2264-C and SPH simulations of a collapsing clump

The earliest phases of massive star formation in clusters are still poorly understood. Here, we test the hypothesis for high-mass star formation proposed in our earlier paper (Peretto et al. 2006). In order to confirm the physical validity of this hypothesis, we carried out IRAM Plateau de Bure interferometer observations of NGC 2264-C and performed SPH numerical simulations of the collapse of a Jeans-unstable, prolate dense clump. Our Plateau de Bure observations reveal the presence of a new compact source (C-MM13) located only \~ 10000 AU away, but separated by ~ 1.1 km/s in (projected) velocity, from the most massive Class 0 object (C-MM3) lying at the very center of NGC 2264-C. Detailed comparison with our numerical SPH simulations supports the view that NGC 2264-C is an elongated cluster-forming clump in the process of collapsing and fragmenting along its long axis, leading to a strong dynamical interaction and possible protostar merger in the central region of the clump. The present study also sets several quantitative constraints on the initial conditions of large-scale collapse in NGC 2264-C. Our hydrodynamic simulations indicate that the observed velocity pattern characterizes an early phase of protocluster collapse which survives for an only short period of time (i.e., < 10^5 yr). To provide a good match to the observations the simulations require an initial ratio of turbulent to gravitational energy of only ~ 5 %, which strongly suggests that the NGC 2264-C clump is structured primarily by gravity rather than turbulence. The required "cold'' initial conditions may result from rapid compression by an external trigger.Comment: 15 pages, 8 figures, accepted for publication in A&