Transitions Induced by the Discreteness of Molecules in a Small Autocatalytic System

Autocatalytic reaction system with a small number of molecules is studied numerically by stochastic particle simulations. A novel state due to fluctuation and discreteness in molecular numbers is found, characterized as extinction of molecule species alternately in the autocatalytic reaction loop. Phase transition to this state with the change of the system size and flow is studied, while a single-molecule switch of the molecule distributions is reported. Relevance of the results to intracellular processes are briefly discussed.Comment: 5 pages, 4 figure

Can the nutrient dynamics of a northern hardwood forest explain variation in its trophic structure?

Background/Question/Methods: A time series of Lepidoptera larvae (caterpillar) abundance and biomass in the northern hardwood forests of central New Hampshire, USA, shows large interannual fluctuations in aggregated caterpillar biomass (52-fold variation in mg caterpillars/ 8000 leaves) that were spatially correlated across a regional landscape. Primary production of these mature forests has not varied over this period, and many hundreds of Lepidoptera species share comparatively few host plants. Therefore, interannual changes in nutritional quality of even one host plant species may be capable of generating correlated population dynamics for many species in the Lepidoptera community. We tested the hypothesis that variation in soil nutrient availability influences foliar chemistry and ultimately produces a bottom-up force capable influencing the aggregated biomass of the forest's dominant herbivores.

Results/Conclusions: Over a period of four years, measures of nutritional quality for herbivores in three of the forest's four dominant understory tree species (Acer saccharum, Acer pensylvanicum, and Viburnum alnifolium) displayed considerable variation that was consistent across the landscape. Foliar nitrogen (N) content and two metrics of secondary metabolite concentration—total phenolics and condensed tannin—all varied by up to 20% among years. Resin bag extracts of NH4+, NO2- /NO3- and PO4+ showed soil mineral nutrient availability displayed six-fold variation that was consistent with the pattern in foliar N, and a whole tree in situ fertilization experimental manipulation produced rapid effects on foliar chemistry. Finally, variation in the forewing lengths of free-flying moths showed an interannual concordance among species within the group of early season feeders that was also consistent with patterns in foliar quality—suggesting collections of species experience correlated variations in larval growth performance.
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Virtualization Infrastructure within the Controls Environment of the Light Sources at HZB

The advantages of visualization techniques and infrastructures with respect to configuration management, high availability and resource management have become obvious also for controls applications. Today a choice of powerful products are easy to use and support desirable functionality, performance, usability and maintainability at very matured levels. This paper presents the architecture of the virtual infrastructure and its relations to the hardware based counterpart as it has emerged for BESSY II and MLS controls within the past decade. Successful experiences as well as abandoned attempts and caveats on some intricate troubles are summarize

A double parton scattering background to Higgs boson production at the LHC

The experimental capability of recognizing the presence of b quarks in complex hadronic final states has addressed the attention towards final states with b\bar{b} pairs for observing the production of the Higgs boson at the LHC, in the intermediate Higgs mass range.We point out that double parton scattering processes are going to represent a sizeable background to the process.Comment: 9 pages, 2 figure

Standard Model Higgs Physics at a 4 TeV Upgraded Tevatron

We compute an array of Standard Model Higgs boson (\hsm) signals and backgrounds for a possible upgrade of the Tevatron to E_{\rm cm}=4\tev. Taking \mt\geq 140\gev, and assuming a total accumulated luminosity of L=30\fbi, we find that a Standard Model Higgs boson with \mhsm\lsim 110\gev could almost certainly be detected using the \wpm\hsm\rta l\nu b\anti b mode. A Higgs boson with mass between \sim 120\gev and \sim 140\gev or above \sim 230-250\gev almost certainly would not be seen. A Higgs boson with \mhsm\sim 150\gev or 200\lsim\mhsm\lsim 230-250\gev has a decent chance of being detected in the ZZ\rta 4l mode. There would also be some possibility of discovering the \hsm in the WW\rta l\nu jj mode for 150\lsim\mhsm\lsim 200\gev. Finally, hints of an event excess in the WW\rta ll \nu\nu mode due to the \hsm might emerge for 140\lsim\mhsm\lsim 180\gev. Given the difficult nature of the Higgs boson signals for \mhsm values beyond the reach of LEP-200, and the discontinuous \mhsm range that could potentially be probed, justification of an upgrade of the Tevatron to 4\tev on the basis of its potential for Standard Model Higgs boson discovery would seem inappropriate.Comment: 21 pages; requires phyzzx.tex and tables.tex; full postscript file including embedded figures available via anonymous ftp at ucdhep.ucdavis.edu as [anonymous.gunion]4tev.ps, preprint UCD-94-1

QCD and Yukawa corrections to single-top-quark production via q qbar -> t bbar

We calculate the O(alpha_s) and O(alpha_W m_t^2/M_W^2) corrections to the production of a single top quark via the weak process q qbar -> t bbar at the Fermilab Tevatron and the CERN Large Hadron Collider. An accurate calculation of the cross section is necessary in order to extract |V_tb| from experiment.Comment: LaTeX, 13 pages, replaced with version to appear in Phys. Rev.

More Signatures of the Intermediate Mass Higgs Boson

We examine the potential signatures of the Higgs boson when it decays into a tau-lepton pair. We show that with the proper identification of the tau-jet, this decay mode can lead to the identification of the Higgs boson over most of the intermediate mass range (\mW $<$ \mH $<$ 2 \mW).Comment: 10 pages, LaTeX fil

Compact Frontend-Electronics and Bidirectional 3.3 Gbps Optical Datalink for Fast Proportional Chamber Readout

The 9600 channels of the multi-wire proportional chamber of the H1 experiment at HERA have to be read out within 96 ns and made available to the trigger system. The tight spatial conditions at the rear end flange require a compact bidirectional readout electronics with minimal power consumption and dead material. A solution using 40 identical optical link modules, each transferring the trigger information with a physical rate of 4 x 832 Mbps via optical fibers, has been developed and commisioned. The analog pulses from the chamber can be monitored and the synchronization to the global HERA clock signal is ensured.Comment: 13 pages, 10 figure