Heterotic type IIA duality with fluxes - towards the complete story

In this paper we study the heterotic type IIA duality when fluxes are turned on. We show that many of the known fluxes are dual to each other and claim that certain fluxes on the heterotic side require that the type IIA picture is lifted to M or even F-theory compactifications with geometric fluxes.Comment: 31 pages, references adde

Identification of hip fracture patients from radiographs using Fourier analysis of the trabecular structure: a cross-sectional study

Peer reviewedPublisher PD

The Dispersal Ecology of Rhodesian Sleeping Sickness Following Its Introduction to a New Area

Tsetse-transmitted human and animal trypanosomiasis are constraints to both human and animal health in sub-Saharan Africa, and although these diseases have been known for over a century, there is little recent evidence demonstrating how the parasites circulate in natural hosts and ecosystems. The spread of Rhodesian sleeping sickness (caused by Trypanosoma brucei rhodesiense) within Uganda over the past 15 years has been linked to the movement of infected, untreated livestock (the predominant reservoir) from endemic areas. However, despite an understanding of the environmental dependencies of sleeping sickness, little research has focused on the environmental factors controlling transmission establishment or the spatially heterogeneous dispersal of disease following a new introduction. In the current study, an annually stratified case-control study of Rhodesian sleeping sickness cases from Serere District, Uganda was used to allow the temporal assessment of correlations between the spatial distribution of sleeping sickness and landscape factors. Significant relationships were detected between Rhodesian sleeping sickness and selected factors, including elevation and the proportion of land which was “seasonally flooding grassland” or “woodlands and dense savannah.” Temporal trends in these relationships were detected, illustrating the dispersal of Rhodesian sleeping sickness into more ‘suitable’ areas over time, with diminishing dependence on the point of introduction in concurrence with an increasing dependence on environmental and landscape factors. These results provide a novel insight into the ecology of Rhodesian sleeping sickness dispersal and may contribute towards the implementation of evidence-based control measures to prevent its further spread

The influence of ethylene and ethylene modulators on shoot organogenesis in tomato

[EN] The influence of ethylene and ethylene modulators on the in vitro organogenesis of tomato was studied using a highly regenerating accession of the wild tomato Solanum pennellii and an F1 plant resulting from a cross between Solanum pennellii and Solanum lycopersicum cv. Anl27, which is known to have a low regeneration frequency. Four ethylene-modulating compounds, each at four levels, were used, namely: cobalt chloride (CoCl 2), which inhibits the production of ethylene; AgNO 3 (SN), which inhibits ethylene action; and Ethephon and the precursor 1-aminocyclopropane-1-carboxylic acid (ACC), which both promote ethylene synthesis. Leaf explants of each genotype were incubated on shoot induction medium supplemented with each of these compounds at 0, 10 or 15 days following bud induction. The results obtained in our assays indicate that ethylene has a significant influence on tomato organogenesis. Concentrations of ethylene lower than the optimum (according to genotype) at the beginning of the culture may decrease the percentage of explants with buds (B), produce a delay in their appearance, or indeed inhibit bud formation. This was observed in S. pennellii and the F1 explants cultured on media with SN (5.8-58.0 ¿M) as well as in the F1 explants cultured on medium with 21.0 ¿M CoCl 2. The percentage of explants with shoots (R) and the mean number of shoots per explant with shoots (PR) also diminished in media that contained SN. Shoots isolated from these explants were less developed compared to those isolated from control explants. On the other hand, ethylene supplementation may contribute to enhancing shoot development. The number of isolable shoots from S. pennellii explants doubled in media with ACC (9.8-98.0 ¿M). Shoots isolated from explants treated with ethylene releasing compounds showed a higher number of nodes when ACC and Ethephon were added at 10 days (in F1 explants) or at 15 days (in S. pennellii) after the beginning of culture. Thus, the importance of studying not only the concentration but also the timing of the application of regulators when developing regeneration protocols has been made manifest. An excess of ethylene supplementation may produce an inhibitory effect, as was observed when using Ethephon (17.2-69.0 ¿M). These results show the involvement of ethylene in tomato organogenesis and lead us to believe that ethylene supplementation may contribute to enhancing regeneration and shoot development in tomato. © 2012 Springer Science+Business Media B.V.Carlos Trujillo has a predoctoral fellowship from the Spanish 'Ministerio de Educacion y Ciencia'. This work has been funded by Universitat Politecnica de Valencia (PAID 05-10). The technical assistance of N. Palacios and the revision of the manuscript's English by J. Bergen are gratefully acknowledged.Trujillo Moya, C.; Gisbert Domenech, MC. (2012). The influence of ethylene and ethylene modulators on shoot organogenesis in tomato. Plant Cell, Tissue and Organ Culture. 111(1):141-148. https://doi.org/10.1007/s11240-012-0168-zS1411481111Abeles FB, Morgan PW, Saltveit ME (1992) Ethylene in plant biology. Academic Press, San DiegoBhatia P, Ashwath N, Senaratna T, David M (2004) Tissue culture studies of tomato (Lycopersicon esculentum). Plant Cell Tiss Org Cult 78:1–21Bhatia P, Ashwath N, Midmore DJ (2005) Effects of genotype, explant orientation, and wounding on shoot regeneration in tomato. In Vitro Cell Dev Biol-Plant 41:457–464Biddington NL (1992) The Influence of ethylene in plant-tissue culture. Plant Growth Regul 11:173–187Brown DC, Thorpe TA (1995) Crop improvement through tissue culture. World J Microbiol Biotechnol 11(4):409–415Chraibi KMB, Latche A, Roustan JP, Fallot J (1991) Stimulation of shoot regeneration from cotyledons of Helianthus annuus by the ethylene inhibitors,silver and cobalt. Plant Cell Rep 10:204–207Devi R, Dhaliwal MS, Kaur A, Gosal SS (2008) Effect of growth regulators on in vitro morphogenic response of tomato. Indian J Biotechnol 7:526–530Dias LLC, Santa-Catarina C, Ribeiro DM, Barros RS, Floh EIS, Otoni WC (2009) Ethylene and polyamine production patterns during in vitro shoot organogenesis of two passion fruit species as affected by polyamines and their inhibitor. Plant Cell Tiss Org Cult 99:199–208Dimasi-Theriou K, Economou AS (1995) Ethylene enhances shoot formation in cultures of the peach rootstock GF-677 (Prunus persica × P. amygdalus). Plant Cell Rep 15:87–90Gisbert C, Arrillaga I, Roig LA, Moreno V (1999) Adquisition of a collection of Lycopersicon pennellii (Corr. D’Arcy) transgenic plants with uidA and nptII marker genes. J Hortic Sci Biotechnol 74:105–109Hughes KW (1981) In vitro ecology: exogenous factors affecting growth and morphogenesis in plant culture systems. Environ Exp Bot 21:281–288Huxter TJ, Thorpe TA, Reid DM (1981) Shoot initiation in light- and darkgrown tobacco callus: the role of ethylene. Physiol Plant 53:319–326Kumar PP, Lakshmanan P, Thorpe TA (1998) Regulation of morphogenesis in plant tissue culture by ethylene. In Vitro Cell Dev Biol Plant 34:94–103Lima JE, Benedito VA, Figueira A, Peres LEP (2009) Callus, shoot and hairy root formation in vitro as affected by the sensitivity to auxin and ethylene in tomato mutants. Plant Cell Rep 28:1169–1177Lu J, Vahala J, Pappinen A (2011) Involvement of ethylene in somatic embryogenesis in Scots pine (Pinus sylvestris L.). Plant Cell Tiss Org Cult 107:25–33Mohiuddin AKM, Chowdhury MKU, Abdullah ZC, Napis S (1997) Influence of silver nitrate (ethylene inhibitor) on cucumber in vitro shoot regeneration. Plant Cell Tiss Org Cult 51:75–78Moshkov IE, Novikova GV, Hall MA, George EF (2008) Plant Growth Regulators III: ethylene. In: George EF, Hall MA, Klerk G-JD (eds) Plant Propaga-tion by Tissue Culture, vol 1. 3rd edn. Springer, The Netherlands, pp 239–248Murashige T, Skoog F (1962) A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol Plant 15:473–497Osman MG, Khalafalla MM (2010) Promotion of in vitro shoot formation from shoot tip of tomato (Lycopersicon esculentum Mill. cv. Omdurman) by ethylene inhibitors. Int J Curr Res 4:82–86Ptak A, El Tahchy A, Wyzgolik G, Henry M, Laurain-Mattar D (2010) Effects of ethylene on somatic embryogenesis and galantamine content in Leucojum aestivum L. cultures. Plant Cell Tiss Org Cult 102:61–67Pua EC, Sim GE, Chi GL, Kong LF (1996) Synergistic effects of ethylene inhibitors and putrescine on shoot regeneration from hypocotyl explants of Chinese radish (Raphanus sativus L. var. longipinnatus Bailey) in vitro. Plant Cell Rep 15:685–690Reid MS (1995) Ethylene in plant growth, development and senescence. In: Davies PJ (ed) Plant hormones: physiology, biochemistry and molecular biology, 2nd edn. Kluwer Acad Publ, The Netherlands, pp 486–508Trujillo-Moya C, Gisbert C, Vilanova S, Nuez F (2011) Localization of QTLs for in vitro plant regeneration in tomato. BMC Plant Biol 11: art.140Tsuchisaka A, Theologis A (2004) Heterodimeric interactions among the 1-amino-cyclopropane-1-carboxylate synthase polypeptides encoded by the Arabidopsis gene family. Proc Natl Acad Sci USA 101:2275–2280Vogel JP, Woeste KE, Theologis A, Kieber JJ (1998) Recessive and dominant mutations in the ethylene biosynthetic gene ACS5 of Arabidopsis confer cytokinin insensitivity and ethylene overproduction, respectively. Proc Natl Acad Sci USA 95:4766–477

The stellar and sub-stellar IMF of simple and composite populations

The current knowledge on the stellar IMF is documented. It appears to become top-heavy when the star-formation rate density surpasses about 0.1Msun/(yr pc^3) on a pc scale and it may become increasingly bottom-heavy with increasing metallicity and in increasingly massive early-type galaxies. It declines quite steeply below about 0.07Msun with brown dwarfs (BDs) and very low mass stars having their own IMF. The most massive star of mass mmax formed in an embedded cluster with stellar mass Mecl correlates strongly with Mecl being a result of gravitation-driven but resource-limited growth and fragmentation induced starvation. There is no convincing evidence whatsoever that massive stars do form in isolation. Various methods of discretising a stellar population are introduced: optimal sampling leads to a mass distribution that perfectly represents the exact form of the desired IMF and the mmax-to-Mecl relation, while random sampling results in statistical variations of the shape of the IMF. The observed mmax-to-Mecl correlation and the small spread of IMF power-law indices together suggest that optimally sampling the IMF may be the more realistic description of star formation than random sampling from a universal IMF with a constant upper mass limit. Composite populations on galaxy scales, which are formed from many pc scale star formation events, need to be described by the integrated galactic IMF. This IGIMF varies systematically from top-light to top-heavy in dependence of galaxy type and star formation rate, with dramatic implications for theories of galaxy formation and evolution.Comment: 167 pages, 37 figures, 3 tables, published in Stellar Systems and Galactic Structure, Vol.5, Springer. This revised version is consistent with the published version and includes additional references and minor additions to the text as well as a recomputed Table 1. ISBN 978-90-481-8817-

Physicians perceived usefulness of high-cost diagnostic imaging studies: results of a referral study in a German medical quality network

BACKGROUND: Medical and technological progress has led to increased numbers of diagnostic tests, some of them inducing high financial costs. In Germany, high-cost diagnostic imaging is performed by a medical specialist after referral by a general practitioner (GP) or specialist in primary care. The aim of this study was to evaluate the physicians' perceived usefulness of high-cost diagnostic imaging in patients with different clinical conditions. METHODS: Thirty-four GPs, one neurologist and one orthopaedic specialist in ambulatory care from a Medical Quality Network documented 234 referrals concerning 97 MRIs, 96 CTs-scan and 41 intracardiac catheters in a three month period. After having received the test results, they indicated if these were useful for diagnosis and treatment of the patient. RESULTS: The physicians' perceived usefulness of tests was lowest in suspected cerebral disease (40% of test results were seen as useful), cervical spine problems (64%) and unexplained abdominal complaints (67%). The perceived usefulness was highest in musculoskeletal symptoms (94%) and second best in cardiological diseases (82%). CONCLUSION: The perceived usefulness of high-cost diagnostic imaging was lower in unexplained complaints than in specific diseases. Interventions to improve the effectiveness and efficiency of test ordering should focus on clinical decision making in conditions where GPs perceived low usefulness

Increased human defensine levels hint at an inflammatory etiology of bisphosphonate-associated osteonecrosis of the jaw: An immunohistological study

<p>Abstract</p> <p>Background</p> <p>Human β-defensins (hBD) are antimicrobial peptides that are an integral part of bone innate immunity. Recently, it could be shown that expression of hBD-1, -2 and -3 were upregulated in cases of osteomyelitis of the jaws. In order to gain insight into the possible impairment of hBD metabolism in bisphosphonate-associated osteonecrosis of the jaws (BONJ), the present exploratory study was designed so as to determine the qualitative and quantitative expression of afore mentioned hBDs in BONJ and infected osteoradionecrosis (ORN), both of which represent inflammatory bone diseases.</p> <p>Methods</p> <p>Bone samples were collected from patients with BONJ (n = 20) and ORN (n = 20). Non-infected healthy bone samples (n = 20) were included as controls. Immunohistological staining in an autostainer was carried out by the (Strept-ABC)-method against hBD-1,-2,-3. Specific positive vs. negative cell reaction of osteocytes (labeling index) near the border of bony resection was determined and counted for quantitative analysis. Number of vital osteocytes vs. empty osteocytes lacunae was compared between groups.</p> <p>Results</p> <p>hBD-1,-2 and -3 could be detected in BONJ as well as ORN and healthy bone samples. Immunoreactivity against hBD-2 and -3 was significantly higher in BONJ than in ORN and healthy jaw bone samples. Number of empty osteocyte lacunae was significantly higher in ORN compared with BONJ (<it>P </it>= 0.001).</p> <p>Conclusion</p> <p>Under the condition of BONJ an increased expression of hBD-1,-2,-3 is detectable, similarly to the recently described upregulation of defensins in chronically infected jaw bones. It remains still unclear how these findings may relate to the pathoetiology of these diseases and whether this is contributing to the development of BONJ and ORN or simply an after effect of the disease.</p

Clusters of galaxies : observational properties of the diffuse radio emission

Clusters of galaxies, as the largest virialized systems in the Universe, are ideal laboratories to study the formation and evolution of cosmic structures...(abridged)... Most of the detailed knowledge of galaxy clusters has been obtained in recent years from the study of ICM through X-ray Astronomy. At the same time, radio observations have proved that the ICM is mixed with non-thermal components, i.e. highly relativistic particles and large-scale magnetic fields, detected through their synchrotron emission. The knowledge of the properties of these non-thermal ICM components has increased significantly, owing to sensitive radio images and to the development of theoretical models. Diffuse synchrotron radio emission in the central and peripheral cluster regions has been found in many clusters. Moreover large-scale magnetic fields appear to be present in all galaxy clusters, as derived from Rotation Measure (RM) studies. Non-thermal components are linked to the cluster X-ray properties, and to the cluster evolutionary stage, and are crucial for a comprehensive physical description of the intracluster medium. They play an important role in the cluster formation and evolution. We review here the observational properties of diffuse non-thermal sources detected in galaxy clusters: halos, relics and mini-halos. We discuss their classification and properties. We report published results up to date and obtain and discuss statistical properties. We present the properties of large-scale magnetic fields in clusters and in even larger structures: filaments connecting galaxy clusters. We summarize the current models of the origin of these cluster components, and outline the improvements that are expected in this area from future developments thanks to the new generation of radio telescopes.Comment: Accepted for the publication in The Astronomy and Astrophysics Review. 58 pages, 26 figure

Measurement and Interpretation of Fermion-Pair Production at LEP energies above the Z Resonance

This paper presents DELPHI measurements and interpretations of cross-sections, forward-backward asymmetries, and angular distributions, for the e+e- -> ffbar process for centre-of-mass energies above the Z resonance, from sqrt(s) ~ 130 - 207 GeV at the LEP collider. The measurements are consistent with the predictions of the Standard Model and are used to study a variety of models including the S-Matrix ansatz for e+e- -> ffbar scattering and several models which include physics beyond the Standard Model: the exchange of Z' bosons, contact interactions between fermions, the exchange of gravitons in large extra dimensions and the exchange of sneutrino in R-parity violating supersymmetry.Comment: 79 pages, 16 figures, Accepted by Eur. Phys. J.

A Determination of the Centre-of-Mass Energy at LEP2 using Radiative 2-fermion Events

Using e+e- -> mu+mu-(gamma) and e+e- -> qqbar(gamma) events radiative to the Z pole, DELPHI has determined the centre-of-mass energy, sqrt{s}, using energy and momentum constraint methods. The results are expressed as deviations from the nominal LEP centre-of-mass energy, measured using other techniques. The results are found to be compatible with the LEP Energy Working Group estimates for a combination of the 1997 to 2000 data sets.Comment: 20 pages, 6 figures, Accepted by Eur. Phys. J.