Warm Cores around Regions of Low-Mass Star Formation

Warm cores (or hot corinos) around low-mass protostellar objects show a rich chemistry with strong spatial variations. This chemistry is generally attributed to the sublimation of icy mantles on dust grains initiated by the warming effect of the stellar radiation. We have used a model of the chemistry in warm cores in which the sublimation process is based on extensive laboratory data; these data indicate that sublimation from mixed ices occurs in several well-defined temperature bands. We have determined the position of these bands for the slow warming by a solar-mass star. The resulting chemistry is dominated by the sublimation process and by subsequent gas-phase reactions; strong spatial and temporal variations in certain molecular species are found to occur, and our results are, in general, consistent with observational results for the well-studied source IRAS 16293-2422. The model used is similar to one that describes the chemistry of hot cores. We infer that the chemistry of both hot cores and warm cores may be described by the same model (suitably adjusted for different physical parameters).Comment: 11 pages, 5 figures, 2 tables. Accepted by MNRA

Incremental Principal Component Analysis Exact implementation and continuity corrections

This paper describes some applications of an incremental implementation of the principal component analysis (PCA). The algorithm updates the transformation coefficients matrix on-line for each new sample, without the need to keep all the samples in memory. The algorithm is formally equivalent to the usual batch version, in the sense that given a sample set the transformation coefficients at the end of the process are the same. The implications of applying the PCA in real time are discussed with the help of data analysis examples. In particular we focus on the problem of the continuity of the PCs during an on-line analysis.Comment: accepted at http://www.icinco.org

Our astrochemical heritage

Our Sun and planetary system were born about 4.5 billion years ago. How did this happen and what is our heritage from these early times? This review tries to address these questions from an astrochemical point of view. On the one hand, we have some crucial information from meteorites, comets and other small bodies of the Solar System. On the other hand, we have the results of studies on the formation process of Sun-like stars in our Galaxy. These results tell us that Sun-like stars form in dense regions of molecular clouds and that three major steps are involved before the planet formation period. They are represented by the pre-stellar core, protostellar envelope and protoplanetary disk phases. Simultaneously with the evolution from one phase to the other, the chemical composition gains increasing complexity. In this review, we first present the information on the chemical composition of meteorites, comets and other small bodies of the Solar System, which is potentially linked to the first phases of the Solar System's formation. Then we describe the observed chemical composition in the pre-stellar core, protostellar envelope and protoplanetary disk phases, including the processes that lead to them. Finally, we draw together pieces from the different objects and phases to understand whether and how much we inherited chemically from the time of the Sun's birth.Comment: Invited review to be published in "The Astronomy and Astrophysics Review

Near-arcsecond resolution observations of the hot corino of the solar type protostar IRAS 16293-2422

Complex organic molecules have previously been discovered in solar type protostars, raising the questions of where and how they form in the envelope. Possible formation mechanisms include grain mantle evaporation, interaction of the outflow with its surroundings or the impact of UV/X-rays inside the cavities. In this Letter we present the first interferometric observations of two complex molecules, CH3CN and HCOOCH3, towards the solar type protostar IRAS16293-2422. The images show that the emission originates from two compact regions centered on the two components of the binary system. We discuss how these results favor the grain mantle evaporation scenario and we investigate the implications of these observations for the chemical composition and physical and dynamical state of the two components.Comment: 5 pages (apjemulate), 2 figures; accepted by ApJ

Role of Fibroblast Growth Factor Receptor 2 in Pancreatic Cancer: Potential Target for New Therapeutic Approach?

Fibroblast growth factors and their receptors play a key role in cell proliferation, migration and differentiation. Fibroblast growth factor receptor 2 (FGFR2) is involved in carcinogenesis and its altered expression has been shown in several tumors, such as breast, thyroid and pancreatic cancer. The two isoforms of FGFR2 gene, FGFR2- IIIb (also known as KGFR) and FGFR2-IIIc have been shown to exert differential roles in pancreatic cancer. FGFR2- IIIc supports pancreatic cell proliferation, while overexpression of FGFR2-IIIb is correlated to major invasion and metastasis formation. This review focuses on the role of FGFR2 signaling in pancreatic adenocarcinoma and the potential use of FGFR2 tissutal expression as a predictive and/or prognostic marker. Moreover, it will discuss about the potential use of strategies for FGFR2 signaling inhibition in the treatment of pancreatic cancer

Toll-like receptor-mediated signaling cascade as a regulator of the inflammation network during alcoholic liver disease

Chronic abuse of alcohol leads to various histological abnormalities in the liver. These are conditions collectively known as alcoholic liver disease (ALD). Currently, ALD is considered to be one of the major causes of death worldwide. An impaired intestinal barrier with related endotoxemia is among the various pathogenetic factors. This is mainly characterized by circulating levels of lipopolysaccharide (LPS), considered critical for the onset of intra-hepatic inflammation. This in turn promotes hepatocellular damage and fibrosis in ALD. Elevated levels of LPS exert their effects by binding to Toll-like receptors (TLRs) which are expressed by all liver-resident cells. The activation of TLR signaling triggers an overproduction and release of some cytokines, which promote an autocatalytic cascade of other proinflammatory signals. In this review, we provide an overview of the mechanisms that sustain LPS-mediated activation of TLR signaling, reporting current experimental and clinical evidence of its role during inflammation in ALD

Benefit-cost analysis of participatory breeding program in Syria

Participatory plant breeding is seen by several scientists as a way to overcome the limitations of conventional breeding by offering farmers the possibility of deciding which varieties better suit their needs and conditions without exposing them to any risk. It exploits the potential gains of breeding for specific adaptation through the selection in the marginal environment. The participation of farmers increases the probability and speed of adoption as well as the breeding efficiency and the effectiveness of the breeding program. The objective of this study is to estimate and compare the benefits and costs of participatory and conventional barley breeding programs. Benefit-cost analysis was used to analyze the costs and benefits of the PPB program at ICARDA and the conventional program at ICARDA and NARS