New massive supergravity multiplets

We present new off-shell formulations for the massive superspin-3/2 multiplet. In the massless limit, they reduce respectively to the old minimal (n=-1/3) and non-minimal ($n\neq -1/3, 0$) linearized formulations for 4D N=1 supergravity. Duality transformations, which relate the models constructed, are derived.Comment: 18 pages, LaTeX; v2: minor changes, references adde

Atmospheric lepton fluxes at ultrahigh energies

In order to estimate the possibility to observe exotic physics in a neutrino telescope, it is essential to first understand the flux of atmospheric neutrinos, muons and dimuons. We study the production of these leptons by high-energy cosmic rays. We identify three main sources of muons of energy E > 10^6 GeV: the weak decay of charm and bottom mesons and the electromagnetic decay of unflavored mesons. Contrary to the standard assumption, we find that eta mesons, not the prompt decay of charm hadrons, are the dominant source of atmospheric muons at these energies. We show that, as a consequence, the ratio between the neutrino and muon fluxes is significantly reduced. For dimuons, which may be a background for long-lived staus produced near a neutrino telescope, we find that pairs of E ~ 10^7 GeV forming an angle above 10^-6 rad are produced through D (80%) or B (10%) meson decay and through Drell-Yan proceses (10%). The frequency of all these processes has been evaluated using the jet code PYTHIA.Comment: 10 pages, 4 figures; published versio

To Search or not to Search: Where is the Mobile Search Market Heading? Results from a Survey with Experts

Web search providers have a highly successful business model in place, which has rendered them amongst the most profitable companies on the internet. The mobile sector is expanding rapidly with the number of worldwide subscribers estimated to reach 5 billions by 2012 and with two-digit growth rates in the number of mobile internet connections. Consequently, many observers consider mobile search as the 'next big market'. However, there is little evidence so far to support such high expectations. In addition, we spot a general lack of studies based on large public data sets, which employ reproducible methods to forecast the evolution of trends in the sector. Surprisingly, whereas some market research reports dedicated solely to mobile search were published a few years ago, just when mobile search is moving to become a mainstream application, there appear to be no comprehensive recent studies about where the mobile search market is going. In this paper we report and analyse the collective opinions of a group of experts on the prospects of mobile search. The research we present is based on a two-round Delphi exercise. The first round of such exercise was conducted online in order to reach a wide community of experts and to cover a broad range of expertise. The second round was carried out face-to-face with a selection of respondents to discuss in depth the results of the online questionnaire. To get the prospective dimension into the Delphi discussion, we proposed seven distinct scenarios. This set a common ground for participants to engage into a forwardlooking debate and to focus their attention onto prospective drivers and barriers rather than solely onto today's landscape. Our Delphi study confirms the high expectations and bright future experts see for the mobile search market, but with noteworthy nuances. We found that the experts' optimism is rooted in the conviction that all critical technological components are already available and that only some system integration is missing. Our paper argues that there is no adequate market pull response to such technology push. Undeniably some (trial) applications are under way, but their business models are still insufficiently defined and companies are experimenting with different business ideas. Irrespectively of the business model, however, experts single out user-centric interfaces as the most The manuscript was submitted on 15th February 2010. This work was supported in part by the European Commission's coordination action CHORUS+ (ICT-2009.1.5 Grant 249008). Corresponding author: [email protected] critical element for increased mobile search take up. Today's interfaces and applications are not satisfactory in terms of users' needs and desires, which is delaying massive adoption. Another essential component for adoption is trust in the service provider. The liability and responsibility of the different players (telecom operators, search engine providers, device manufacturers, etc) needs to be scrutinized. Our study also presents the views of experts on how privacy and personal data usage are influencing the evolution of mobile search. The paper concludes with some suggestions for fostering the evolution of the mobile search domain by increasing the interoperability of services, assuring the openness and mash-ups of content and services, developing personal identity data management systems to improve user acceptance and enhance trust and by supporting research, both on the technologies that are required to enable more advanced used of mobile search applications, and supporting living labs a experimental platform to test new application and innovative business models

Properties of hyperkahler manifolds and their twistor spaces

We describe the relation between supersymmetric sigma-models on hyperkahler manifolds, projective superspace, and twistor space. We review the essential aspects and present a coherent picture with a number of new results.Comment: 26 pages. v2: Sign mistakes corrected; Kahler potential explicitly calculated in example; references added. v3: Published version--several small clarifications per referee's reques

6D Supersymmetry, Projective Superspace and 4D, N=1 Superfields

In this note, we establish the formulation of 6D, N=1 hypermultiplets in terms of 4D chiral-nonminimal (CNM) scalar multiplets. The coupling of these to 6D, N=1 Yang-Mills multiplets is described. A 6D, N=1 projective superspace formulation is given in which the above multiplets naturally emerge. The covariant superspace quantization of these multiplets is studied in details.Comment: 27 pages, LaTeX, minor changes, references adde

SNHG15 is a bifunctional MYC-regulated noncoding locus encoding a lncRNA that promotes cell proliferation, invasion and drug resistance in colorectal cancer by interacting with AIF

Background: Thousands of long noncoding RNAs (lncRNAs) are aberrantly expressed in various types of cancers, however our understanding of their role in the disease is still very limited. Methods: We applied RNAseq analysis from patient-derived data with validation in independent cohort of patients. We followed these studies with gene regulation analysis as well as experimental dissection of the role of the identified lncRNA by multiple in vitro and in vivo methods. Results: We analyzed RNA-seq data from tumors of 456 CRC patients compared to normal samples, and identified SNHG15 as a potentially oncogenic lncRNA that encodes a snoRNA in one of its introns. The processed SNHG15 is overexpressed in CRC tumors and its expression is highly correlated with poor survival of patients. Interestingly, SNHG15 is more highly expressed in tumors with high levels of MYC expression, while MYC protein binds to two E-box motifs on SNHG15 sequence, indicating that SNHG15 transcription is directly regulated by the oncogene MYC. The depletion of SNHG15 by siRNA or CRISPR-Cas9 inhibits cell proliferation and invasion, decreases colony formation as well as the tumorigenic capacity of CRC cells, whereas its overexpression leads to opposite effects. Gene expression analysis performed upon SNHG15 inhibition showed changes in multiple relevant genes implicated in cancer progression, including MYC, NRAS, BAG3 or ERBB3. Several of these genes are functionally related to AIF, a protein that we found to specifically interact with SNHG15, suggesting that the SNHG15 acts, at least in part, by regulating the activity of AIF. Interestingly, ROS levels, which are directly regulated by AIF, show a significant reduction in SNHG15-depleted cells. Moreover, knockdown of SNHG15 increases the sensitiveness of the cells to 5-FU, while its overexpression renders them more resistant to the chemotherapeutic drug. Conclusion: Altogether, these results describe an important role of SNHG15 in promoting colon cancer and mediating drug resistance, suggesting its potential as prognostic marker and target for RNA-based therapies

Confinement, the gluon propagator and the interquark potential for heavy mesons

The interquark static potential for heavy mesons described by a massive One Gluon Exchange interaction obtained from the propagator of the truncated Dyson-Schwinger equations does not reproduced the expected Cornell potential. I show that no formulation based on a finite propagator will lead to confinement of quenched QCD. I propose a mechanism based on a singular nonperturbative coupling constant which has the virtue of giving rise to a finite gluon propagator and (almost) linear confinement. The mechanism can be slightly modified to produce the screened potentials of unquenched QCD.Comment: 12 pages and 7 figure

Possible symmetries of the superconducting order parameter in a hexagonal ferromagnet

We study the order parameter symmetry in a hexagonal crystal with co-existing superconductivity and ferromagnetism. An experimental example is provided by carbon-based materials, such as graphite-sulfur composites, in which an evidence of such co-existence has been recently discovered. The presence of a non-zero magnetization in the normal phase brings about considerable changes in the symmetry classification of superconducting states, compared to the non-magnetic case.Comment: 4 pages, REVTe

80-річчя академіка НАН України В.І. Старостенка

Qualitative and quantitative changes in soil and fertilizer-derived organic N fractions were assessed during a cropping season in an intertropical Alfisol, under maize and pasture, fertilized with15 N-urea. Before the sowing, after fertilizing and after the harvest, the organic N of top soil samples was fractionated by a two-step acid hydrolysis under reflux (H1 = 1 M HCl for 3 h; H2 = 3 M HCl for 3 h). The total hydrolysable N (HN) from H1 decreased significantly during the cropping season in both maize and pasture soils. Contrastingly, the content of HN from H2 and that of non-hydrolysable N did not vary significantly during the cropping season. The easily hydrolysable fractions, especially amino acid N, amino sugar N and amide N, were the most active N pools and the major source of N potentially available for plants. The urea-derived N that remained in the soil was mainly in organic forms at both 7 and 108 d after fertilizing (70–82% and 93–98%, respectively), higher figures being found in pasture than in maize soil. The total amount of urea-derived HN decreased significantly during the crop period in both maize and pasture soils. This decrease was largely due to the decline in HN from H1. The amount of non-hydrolysable urea-derived N was significantly higher in pasture than in maize soil and it decreases in the former and increases in the latter, during the cropping season. During the crop period, the decrease of urea-derived organic N was 4.6 to 9.1 times higher than that of native organic N. Shortly after fertilizing, the proportion of urea-derived N in the easily hydrolysable (H1) organic fractions was higher than that of soil N, whereas the reverse was true for the slowly hydrolysable (H2) or insoluble fractions. These differences were less marked, but still significant, at the end of cropping. The easily hydrolysable organic N fractions were more sensitive than total N to the impact of land use intensification and are, therefore, a more useful index for early detection of soil biological degradation.Peer reviewe