PDFS: Practical Data Feed Service for Smart Contracts

Smart contracts are a new paradigm that emerged with the rise of the blockchain technology. They allow untrusting parties to arrange agreements. These agreements are encoded as a programming language code and deployed on a blockchain platform, where all participants execute them and maintain their state. Smart contracts are promising since they are automated and decentralized, thus limiting the involvement of third trusted parties, and can contain monetary transfers. Due to these features, many people believe that smart contracts will revolutionize the way we think of distributed applications, information sharing, financial services, and infrastructures. To release the potential of smart contracts, it is necessary to connect the contracts with the outside world, such that they can understand and use information from other infrastructures. For instance, smart contracts would greatly benefit when they have access to web content. However, there are many challenges associated with realizing such a system, and despite the existence of many proposals, no solution is secure, provides easily-parsable data, introduces small overheads, and is easy to deploy. In this paper we propose PDFS, a practical system for data feeds that combines the advantages of the previous schemes and introduces new functionalities. PDFS extends content providers by including new features for data transparency and consistency validations. This combination provides multiple benefits like content which is easy to parse and efficient authenticity verification without breaking natural trust chains. PDFS keeps content providers auditable, mitigates their malicious activities (like data modification or censorship), and allows them to create a new business model. We show how PDFS is integrated with existing web services, report on a PDFS implementation and present results from conducted case studies and experiments.Comment: Blockchain; Smart Contracts; Data Authentication; Ethereu

Strategies to link tiny neutrino masses with huge missing mass of the Universe

With the start of the LHC, interest in electroweak scale models for the neutrino mass has grown. In this letter, we review two specific models that simultaneously explain neutrino masses and provide a suitable DM candidate. We discuss the implications of these models for various observations and experiments including the LHC, Lepton Flavor Violating (LFV) rare decays, direct and indirect dark matter searches and Kaon decay.Comment: 17 pages, one diagram, talk given at International Conference on Flavor Physics in the LHC era in Singapor

Custodial SO(4) symmetry and CP violation in N-Higgs-doublet potentials

We study the implementation of global $SO(4)\sim SU(2)_L\otimes SU(2)_R$ symmetry in general potentials with N-Higgs-doublets in order to obtain models with custodial $SO(3)_C$ symmetry. We conclude that any implementation of the custodial SO(4) symmetry is equivalent, by a basis transformation, to a canonical one if $SU(2)_L$ is the gauge factor, $U(1)_Y$ is embedded in $SU(2)_R$ and we require $N$ copies of the doublet representation of $SU(2)_R$. The invariance by SO(4) automatically leads to a CP invariant potential and the basis of the canonical implementation of SO(4) is aligned to a basis where CP-symmetry acts in the standard fashion. We show different but equivalent implementations for the 2HDM, including an implementation not previously considered.Comment: 22pp, REVTeX4. Published versio

Helioseismic Ring Analysis of CME Source Regions

We apply the ring diagram technique to source regions of halo coronal mass ejections (CMEs) to study changes in acoustic mode parameters before, during, and after the onset of CMEs. We find that CME regions associated with a low value of magnetic flux have line widths smaller than the quiet regions implying a longer life-time for the oscillation modes. We suggest that this criterion may be used to forecast the active regions which may trigger CMEs.Comment: Accepted for publication in J. Astrophys. Astr. Also available at http://www2.nso.edu/staff/sushant/paper.htm

Phase Transitions of Charged Scalars at Finite Temperature and Chemical Potential

We calculate the grand canonical partition function at the one-loop level for scalar quantum electrodynamics at finite temperature and chemical potential. A classical background charge density with a charge opposite that of the scalars ensures the neutrality of the system. For low density systems we find evidence of a first order phase transition. We find upper and lower bounds on the transition temperature below which the charged scalars form a condensate. A first order phase transition may have consequences for helium-core white dwarf stars in which it has been argued that such a condensate of charged helium-4 nuclei could exist.Comment: 20 pages, 3 figures. Version accepted for publication in JHE

Sneutrino Mixing Phenomena

In any model with nonzero Majorana neutrino masses, the sneutrino and antisneutrino of the supersymmetric extended theory mix. We outline the conditions under which sneutrino-antisneutrino mixing is experimentally observable. The mass-splitting of the sneutrino mass eigenstates and sneutrino oscillation phenomena are considered.Comment: 12 pages, revtex + axodraw, 1 figure included. Minor change

Supersymmetric Scenarios with Dominant Radiative Neutralino Decay

The radiative decay of the next-to-lightest neutralino into a lightest neutralino and a photon is analyzed in the MSSM. We find that significant regions of the supersymmetric parameter space with large radiative BR's (up to about 100%) do exist. The radiative channel turns out to be enhanced when the neutralino tree-level decays are suppressed either "kinematically" or "dynamically". In general, in the regions allowed by LEP data and not characterized by asymptotic values of the SuSy parameters, the radiative enhancement requires tan beta ~= 1 and/or M_1 ~= M_2, and negative values of \mu. We present typical specific scenarios where these "necessary" conditions are fulfilled, relaxing the usual relation M_1=(5/3)*tan^2(th_W)*M_2. The influence of varying the stop masses and mixing angle when the radiative decay is enhanced is also considered. Some phenomenological consequences of the above picture are discussed.Comment: 32 pages, LaTeX file + 23 figures embedded with epsf.sty. In this revised version, Eq.(3) plus some related notations and text passages have been changed. Minor error corrected in Fig.12(a). The numerical analysis and the conclusions of the paper are not affected. (Includes the erratum to appear in Phys. Rev. D.) Source and ps files are also available at ftp://hpteo.roma1.infn.it/pub/preprints/ambr-mele/Rome1-1148/ or at http://feynman.physics.lsa.umich.edu/~ambros/Physics.html#1

The effect of different bleaching protocols, used with and without sodium ascorbate, on bond strength between composite and enamel

This in vitro study aims to evaluate whether a solution of 10% sodium ascorbate (SA) may exert a beneficial effect on the bonding of composite to enamel after using different bleaching agents and protocols. Microtensile bond strength (μTBS) was evaluated on 72 freshly extracted human central incisors, divided into eight experimental groups and one control group (total n = 9): Group 1 serves as control (nonbleached). Group 2 was bleached with 5% carbamide peroxide. Group 3 was bleached with 5% carbamide peroxide and then treated with 10% SA. Group 4 was bleached with 10% carbamide peroxide. Group 5 was bleached with 10% carbamide peroxide, then treated with 10% SA. Group 6 was bleached with 16% carbamide peroxide. Group 7 was bleached with 16% carbamide peroxide, then treated with 10% SA. Group 8 was bleached with 6% hydrogen peroxide. Group 9 was bleached with 6% hydrogen peroxide, then treated with 10% SA. All groups were restored immediately after the different treatments using a resin composite. The μTBS values were measured using a universal testing machine and statistical analysis was performed by means of normality and variance analyses, SIDAK test for univariate test and multiple comparisons, and Student test to compare μTBS values of each group with the control. The mean μTBS values in groups 2, 4, 6, 8 were significantly lower than controls. For groups 3, 5, 7, 9, subjected to antioxidant (10% SA) application, all μTBS values increased significantly. However, only for Groups 3 and 5 there was no significant difference with the control. Applying 10% SA for 10 min may improve the bond strength composite/bleached enamel just when whitening is performed with 5% and 10% carbamide peroxide