Fred Olness

Selective Transfer of Calcium from an Acidic Compartment to the Mitochondrion of Trypanosoma brucei MEASUREMENTS WITH TARGETED AEQUORINS

Organelle compartments are used by cells as reservoirs of exchangeable Ca2+ and as Ca2+ buffers. The following study uses recombinant aequorins (CYT-AEQ and MT-AEQ) to measure the dynamics of Ca2+ flux between organelles in procyclic forms of the pathogenic protozoan, Trypanosoma brucei. Emphasis is placed on the exchange between an acidic Ca2+ reservoir and the mitochondrion. The mammalian mitochondrial targeting sequence was functional in trypanosomes as determined by immunoblots, immunolocalizations, and the observation that MT-AEQ was in a compartment whose Ca2+ uptake was inhibited 82% with carbonyl cyanide p-trifluoromethoxyphenylhydrazone and KCN. The resting level of free calcium ion concentration in the mitochondrion ([Ca2+]mit) was slightly higher than that in the cytoplasm ([Ca2+]cyt) (400 ± 50 nm and 290 ± 40 nm, respectively). Melittin (125 nm) disrupted Ca2+homeostasis by inducing Ca2+ influx across the plasma membrane. [Ca2+]cyt became slightly elevated to 410 ± 100 nm, whereas [Ca2+]mit was selectively increased approximately 12-fold, with a broad peak at 4.8 ± 1.9 μm. At the peak, the mitochondrion contained approximately three times more free Ca2+ than the cytosol. However, mitochondrial retention of the Ca2+ was transient. Similar selective transport into the mitochondrion was observed when Ca2+ efflux from an acidic compartment was induced with monensin (2 μg/ml) in the presence of 5 mm EGTA. [Ca2+]cyt was transiently elevated to 400 ± 50 nm, whereas [Ca2+]mit was elevated to 3.3±1.3 μm. When cells were treated sequentially with monensin (2 μg/ml) and then melittin (200 nm), mitochondrial Ca2+ transport was normal. However, [Ca2+]cyt became elevated to a level that was 1.4-fold higher than with melittin alone. Overall, these data demonstrate that the trypanosome mitochondrion is not a reservoir of exchangeable Ca2+ in the resting cell. However, Ca2+ is selectively channeled to the mitochondrion from the plasma membrane or acidic Ca2+ storage compartment. Additionally, the acidic compartment contributes to maintenance of Ca2+ homeostasis in response to melittin.

On the intrinsic bottom content of the nucleon and its impact on heavy new physics at the LHC

A bstractHeavy quark parton distribution functions (PDFs) play an important role in several Standard Model and New Physics processes. Most analyses rely on the assumption that the charm and bottom PDFs are generated perturbatively by gluon splitting and do not involve any non-perturbative degrees of freedom. It is clearly necessary to test this hypothesis with suitable QCD processes. Conversely, a non-perturbative, intrinsic heavy quark parton distribution has been predicted in the literature. We demonstrate that to a very good approximation the scale-evolution of the intrinsic heavy quark content of the nucleon is governed by non-singlet evolution equations. This allows us to analyze the intrinsic heavy quark distributions without having to resort to a full-fledged global analysis of parton distribution functions. We exploit this freedom to model intrinsic bottom distributions which are so far missing in the literature in order to estimate the impact of this non-perturbative contribution to the bottom-quark PDF, and on parton-parton luminosities at the LHC. This technique can be applied to the case of intrinsic charm, albeit within the limitations outlined in the following.

Terascale Physics Opportunities at a High Statistics, High Energy Neutrino Scattering Experiment: NuSOnG

This paper presents the physics case for a new high-energy, ultra-high statistics neutrino scattering experiment, NuSOnG (Neutrino Scattering on Glass). This experiment uses a Tevatron-based neutrino beam to obtain over an order of magnitude higher statistics than presently available for the purely weak processes νμ + e- → νμ + e- and νμ + e- → νe + μ-. A sample of Deep Inelastic Scattering events which is over two orders of magnitude larger than past samples will also be obtained. As a result, NuSOnG will be unique among present and planned experiments for its ability to probe neutrino couplings to Beyond the Standard Model physics. Many Beyond Standard Model theories physics predict a rich hierarchy of TeV-scale new states that can correct neutrino cross-sections, through modifications of Zνν couplings, tree-level exchanges of new particles such as Z′s, or through loop-level oblique corrections to gauge boson propagators. These corrections are generic in theories of extra dimensions, extended gauge symmetries, supersymmetry, and more. The sensitivity of NuSOnG to this new physics extends beyond 5 TeV mass scales. This paper reviews these physics opportunities.

Parton distributions and lattice QCD calculations: a community white paper

In the framework of quantum chromodynamics (QCD), parton distribution functions (PDFs) quantify how the momentum and spin of a hadron are divided among its quark and gluon constituents. Two main approaches exist to determine PDFs. The first approach, based on QCD factorization theorems, realizes a QCD analysis of a suitable set of hard-scattering measurements, often using a variety of hadronic observables. The second approach, based on first-principle operator definitions of PDFs, uses lattice QCD to compute directly some PDF-related quantities, such as their moments. Motivated by recent progress in both approaches, in this document we present an overview of lattice-QCD and global-analysis techniques used to determine unpolarized and polarized proton PDFs and their moments. We provide benchmark numbers to validate present and future lattice-QCD calculations and we illustrate how they could be used to reduce the PDF uncertainties in current unpolarized and polarized global analyses. This document represents a first step towards establishing a common language between the two communities, to foster dialogue and to further improve our knowledge of PDFs.

ManeParse: A Mathematica reader for Parton Distribution Functions

Abstract Parton Distribution Functions (PDFs) are essential non-perturbative inputs for calculation of any observable with hadronic initial states. These PDFs are released by individual groups as discrete grids as a function of the Bjorken- x and energy scale Q . The LHAPDF project maintains a repository of PDFs from various groups in a new standardized LHAPDF6 xa0format, additionally older formats such as the CTEQxa0PDS grid format are still in use. ManeParse xa0is a package that provides access to PDFs within Mathematica xa0to facilitate calculation and plotting. The program is self-contained so there are no external links to any FORTRAN , C xa0or C++ xa0programs. The package includes the option to use the built-in Mathematica xa0interpolation or a custom cubic Lagrange interpolation routine which allows for flexibility in the extrapolation (particularly at small x -values). ManeParse xa0is fast enough to enable simple calculations (involving even one or two integrations) in the Mathematica xa0framework. Program summary Program Title: ManeParse Program Files doi: http://dx.doi.org/10.17632/knbsccggg4.1 Licensing provisions: MIT Programming language: Mathematica Nature of problem: PDFs are currently read and interpolated via a FORTRAN xa0or C++ xa0interface. Noxa0method exist to read the LHAPDF6 xa0or CTEQxa0PDFs directly in Mathematica . Solution method: A Mathematica xa0package reads in LHAPDF6 xa0and CTEQxa0PDF files. The PDFs are parsed into a three-dimensional array in Bjorken- x , scattering energy Q , and parton flavor, and are stored in memory. Provided functions give access to the PDF, the PDF uncertainty, the PDF correlations, and the parton–parton Luminosities. The LHAPDF6 xa0info files are converted from YAML format into Mathematica rules.

Impact of the heavy-quark matching scales in PDF fits

We investigate the impact of displaced heavy-quark matching scales in a global fit. The heavy-quark matching scale

xFitter 2.0.0 : an open source QCD Fit framework

mu _{m}

SIMP (Strongly Interacting Massive Particle) Search

μm determines at which energy scale