Void Analysis of Hadronic Density Fluctuations at Phase Transition

The event-to-event fluctuations of hadron multiplicities are studied for a quark system undergoing second-order phase transition to hadrons. Emphasis is placed on the search for an observable signature that is realistic for heavy-ion collisions. It is suggested that in the 2-dimensional y-phi space the produced particles selected in a very narrow p_T window may exhibit clustering patterns even when integrated over the entire emission time. Using the Ising model to simulate the critical phenomenon and taking into account a p_T distribution that depends on the emission time, we study in the framework of the void analysis proposed earlier and find scaling behavior. The scaling exponents turn out to be larger than the ones found before for pure configurations without mixing. The signature is robust in that it is insensitive to the precise scheme of simulating time evolution. Thus it should reveal whether or not the dense matter created in heavy-ion collisions is a quark-gluon plasma before hadronization.Comment: 11 pages in LaTeX + 6 figures in p

Test of the REX-RFQ and status of the front part of the REX-ISOLDE linac

For REX-ISOLDE (Radioactive beam EXperiments at ISOLDE/CERN), a test beamline is built up at the Garching Accelerator Lab. to perform He$^{1+}$-experiments with the RFQ, the matching (rebunching) section between RFQ and IH-DT-linac, the IH-structure and several electrostatic lenses of the REX-ISOLDE-mass separator. In a first step, the beamline is conceived for tests with the RFQ. This paper presents the parameters and the status of the REX-RFQ, the experimental setup and the particle dynamics simulations with the COSY infinity code for beam injection and beam analysis. Furthermore it shows the design and status of the mass separator, the IH- structure and the buncher section. (5 refs)

Purifying and Reversible Physical Processes

Starting from the observation that reversible processes cannot increase the purity of any input state, we study deterministic physical processes, which map a set of states to a set of pure states. Such a process must map any state to the same pure output, if purity is demanded for the input set of all states. But otherwise, when the input set is restricted, it is possible to find non-trivial purifying processes. For the most restricted case of only two input states, we completely characterize the output of any such map. We furthermore consider maps, which combine the property of purity and reversibility on a set of states, and we derive necessary and sufficient conditions on sets, which permit such processes.Comment: 5 pages, no figures, v2: only minimal change

Deregulation of the endogenous C/EBPβ LIP isoform predisposes to tumorigenesis

Two long and one truncated isoforms (termed LAP*, LAP, and LIP, respectively) of the transcription factor CCAAT enhancer binding protein beta (C/EBPbeta) are expressed from a single intronless Cebpb gene by alternative translation initiation. Isoform expression is sensitive to mammalian target of rapamycin (mTOR)-mediated activation of the translation initiation machinery and relayed through an upstream open reading frame (uORF) on the C/EBPbeta mRNA. The truncated C/EBPbeta LIP, initiated by high mTOR activity, has been implied in neoplasia, but it was never shown whether endogenous C/EBPbeta LIP may function as an oncogene. In this study, we examined spontaneous tumor formation in C/EBPbeta knockin mice that constitutively express only the C/EBPbeta LIP isoform from its own locus. Our data show that deregulated C/EBPbeta LIP predisposes to oncogenesis in many tissues. Gene expression profiling suggests that C/EBPbeta LIP supports a pro-tumorigenic microenvironment, resistance to apoptosis, and alteration of cytokine/chemokine expression. The results imply that enhanced translation reinitiation of C/EBPbeta LIP promotes tumorigenesis. Accordingly, pharmacological restriction of mTOR function might be a therapeutic option in tumorigenesis that involves enhanced expression of the truncated C/EBPbeta LIP isoform. KEY MESSAGE: Elevated C/EBPbeta LIP promotes cancer in mice. C/EBPbeta LIP is upregulated in B-NHL. Deregulated C/EBPbeta LIP alters apoptosis and cytokine/chemokine networks. Deregulated C/EBPbeta LIP may support a pro-tumorigenic microenvironment

G-protein alpha-subunits in cytosolic and membranous fractions of human neutrophils

In plasma membranes of human neutrophils, we identified two major pertussis toxin substrates of 40 kDa Mr with pI values of 5.30 and 5.37. Only the acidic of the two substrates was also present in neutrophil cytosol. Two-dimensional tryptic peptide maps revealed a high degree of homology of cytosolic and particulate substrates. Purified G-protein beta gamma-complex stimulated pertussis toxin-catalyzed [32P]ADP-ribosylation of membranous and cytosolic substrates of neutrophils less than 2-fold and 6-fold, respectively. Hydrodynamic properties of the cytosolic substrate strongly suggested that it exists as a monomer. Purified G-protein beta gamma-complex increased the s20,w value of the cytosolic substrate from 3.3 S to 4.0 S. The GTP analogue, guanosine 5'-O-(3-thiotriphosphate), promoted the release of pertussis toxin substrates from plasma membranes. An antiserum raised against a sequence specific for the Gi2 alpha-subunit reacted with 39-40 kDa proteins in plasma membranes and with an apparently single 40 kDa protein in cytosol. We conclude that neutrophil cytosol contains monomeric Gi2 alpha-subunits which--by interacting with hydrophobic beta gamma-complexes--may reversibly bind to the plasma membrane

Integrated Photonic Sensing

Loss is a critical roadblock to achieving photonic quantum-enhanced technologies. We explore a modular platform for implementing integrated photonics experiments and consider the effects of loss at different stages of these experiments, including state preparation, manipulation and measurement. We frame our discussion mainly in the context of quantum sensing and focus particularly on the use of loss-tolerant Holland-Burnett states for optical phase estimation. In particular, we discuss spontaneous four-wave mixing in standard birefringent fibre as a source of pure, heralded single photons and present methods of optimising such sources. We also outline a route to programmable circuits which allow the control of photonic interactions even in the presence of fabrication imperfections and describe a ratiometric characterisation method for beam splitters which allows the characterisation of complex circuits without the need for full process tomography. Finally, we present a framework for performing state tomography on heralded states using lossy measurement devices. This is motivated by a calculation of the effects of fabrication imperfections on precision measurement using Holland-Burnett states.Comment: 19 pages, 7 figure

Numerical observation of non-axisymmetric vesicles in fluid membranes

By means of Surface Evolver (Exp. Math,1,141 1992), a software package of brute-force energy minimization over a triangulated surface developed by the geometry center of University of Minnesota, we have numerically searched the non-axisymmetric shapes under the Helfrich spontaneous curvature (SC) energy model. We show for the first time there are abundant mechanically stable non-axisymmetric vesicles in SC model, including regular ones with intrinsic geometric symmetry and complex irregular ones. We report in this paper several interesting shapes including a corniculate shape with six corns, a quadri-concave shape, a shape resembling sickle cells, and a shape resembling acanthocytes. As far as we know, these shapes have not been theoretically obtained by any curvature model before. In addition, the role of the spontaneous curvature in the formation of irregular crenated vesicles has been studied. The results shows a positive spontaneous curvature may be a necessary condition to keep an irregular crenated shape being mechanically stable.Comment: RevTex, 14 pages. A hard copy of 8 figures is available on reques

Crystal structures of self-assembled nanotubes from flexible macrocycles by weak interactions

8 páginas, 7 figuras, 2 tablas, 2 esquemas.Herein we report the crystal structures of tubular self-assemblies of flexible macrooligolides. The assembly is driven by the propensity of the macrocycles to create nearly flat structures displaying a void space within them and the cooperativity of weak directional interactions such as dipole–dipole interactions and CH***Ohydrogen bonds and non-directional interactions such as van der Waals contacts. The significance of the stereochemistry and the size of the cavity in the formation of the nanotubes are also studied.This research was supported by the Spanish MICINN-FEDER (CTQ2008-03334/BQU, CTQ2008-06806-C02-01/BQU and CTQ2008-06754-C04-01/PPQ), the MSC (RTICC RD06/0020/ 1046) and the Canary Islands FUNCIS (PI 01/06).Peer reviewe

"Safe" Coulomb Excitation of 30Mg

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin nat-Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative de-excitation gamma ray yields the B(E2; 0+ -> 2+) value of 30Mg was determined to be 241(31) e2fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg lies still outside the ``island of inversion''