115,294 research outputs found
Friends of Musselman Library Newsletter Spring 2005
Table of Contents: From the Director: “Forever Free” Abraham Lincoln Exhibit (Robin Wagner, Christina Ericson Hansen ’92, Gabor Boritt); Fortenbaugh Internship Expands (Julia Grover ’06, Anne Kennedy ’05); Bontanicals Brighten Browsing Room (Jim Ramos); Asian Art Award Announced (Karen Drickamer); Apache Visions: Exhibit Features Skateboard Art; Barbara Holley Establishes Preservation Fund for Library (Barbara Holley ’54); Library News: Athletic Windfall, Reading Al Fresco, Library Tunes, Newspaper and Magazine Browsing, Majestic Theatre Exhibit, Civil War Manuscripts, Oral History, FoML Helps New Voters (Henry T. Bream ’24, Jack Bream ’57, Robert C. ’62, Marsha Parker ’62, Dr. William Sunderman Senior ’19, Jake Yingling ’52 and Genevieve Yingling); Student Projects Featured in Music Exhibition (Dr. William Sunderman Senior ’19, Tim Sestrick, Marta Robertson); In Her Own Words; Spring Lecture on Citron (Molly Hutton, Thomas Citron ’47, Virginia Eshbach Citron ’47); Second Spring Friends Lecture: “The Cyclorama Building and the Loss of Cultural Landscape at Gettysburg”; Focus on Philanthropy: Gift Supports Purchases of Nineteenth Century Documents (Dr. Bradley Hoch); Giving Students a Break (Meggan Emler Smith \u2704, Anne Kennedy, Sujita Kong); Spotlight on Collecting: Captivity Narritives (Edward Maharay, Janet Hancock Maharay ’39, Tim Shannon); Weird and Gross in the Librar
Tuning Pythia8 for future colliders
The majority of Monte-Carlo (MC) simulation campaigns for future
colliders has so far been based on the leading-order (LO) matrix elements
provided by Whizard 1.95, followed by parton shower and hadronization in
Pythia6, using the tune of the OPAL experiment at LEP. In this contribution, we
test and develop the interface between Whizard3 and Pythia8. As a first step,
we simulate the process with LO matrix elements, and
compare three tunes in Pythia8: the standard Pythia8 tune, the OPAL tune and
the ALEPH tune. At stable-hadron level, predictions of charged and neutral
hadron multiplicities of these tunes are compared to LEP data, since they are
strongly relevant to the performance of particle flow algorithms.
The events are used to perform a full detector simulation and reconstruction
of the International Large Detector concept (ILD) as an example for a
particle-flow-optimised detector. At reconstruction level, a comparison of the
jet energy resolution in these tunes is presented. We found good agreement with
previous results that were simulated by Whizard1+Pythia6. In addition, the
preliminary next-to-leading order (NLO) results are also presented. This modern
MC simulation chain, with matched NLO matrix elements in the future, should be
introduced to ILC or other future colliders.Comment: 8 pages, 7 figures, 1 table, LCWS 202
Tuning Monte Carlo Generators: The Perugia Tunes
We present 9 new tunes of the pT-ordered shower and underlying-event model in
PYTHIA 6.4. These "Perugia" tunes update and supersede the older "S0" family.
The data sets used to constrain the models include hadronic Z0 decays at LEP,
Tevatron minimum-bias data at 630, 1800, and 1960 GeV, Tevatron Drell-Yan data
at 1800 and 1960 GeV, and SPS min-bias data at 200, 546, and 900 GeV. In
addition to the central parameter set, called "Perugia 0", we introduce a set
of 8 related "Perugia Variations" that attempt to systematically explore soft,
hard, parton density, and colour structure variations in the theoretical
parameters. Based on these variations, a best-guess prediction of the charged
track multiplicity in inelastic, nondiffractive minimum-bias events at the LHC
is made. Note that these tunes can only be used with PYTHIA 6, not with PYTHIA
8. Note: this report was updated in March 2011 with a new set of variations,
collectively labeled "Perugia 2011", that are optimized for matching
applications and which also take into account some lessons from the early LHC
data. In order not to break the original text, these are described separately
in Appendix B. Note 2: a subsequent "Perugia 2012" update is described in
Appendix C.Comment: 46 page
Reducing the Top Quark Mass Uncertainty with Jet Grooming
The measurement of the top quark mass has large systematic uncertainties
coming from the Monte Carlo simulations that are used to match theory and
experiment. We explore how much that uncertainty can be reduced by using jet
grooming procedures. We estimate the inherent ambiguity in what is meant by
Monte Carlo mass to be around 530 MeV without any corrections. This uncertainty
can be reduced by 60% to 200 MeV by calibrating to the W mass and a further 33%
to 140 MeV by applying soft-drop jet grooming (or by 20% more to 170 MeV with
trimming). At e+e- colliders, the associated uncertainty is around 110 MeV,
reducing to 50 MeV after calibrating to the W mass. By analyzing the tuning
parameters, we conclude that the importance of jet grooming after calibrating
to the W mass is to reduce sensitivity to the underlying event.Comment: 21 pages, 7 figure
Forward-Backward Correlations and Event Shapes as probes of Minimum-Bias Event Properties
Measurements of inclusive observables, such as particle multiplicities and
momentum spectra, have already delivered important information on
soft-inclusive ("minimum-bias") physics at the Large Hadron Collider. In order
to gain a more complete understanding, however, it is necessary to include also
observables that probe the structure of the studied events. We argue that
forward-backward (FB) correlations and event-shape observables may be
particulary useful first steps in this respect. We study the sensitivity of
several different types of FB correlations and two event shape variables -
transverse thrust and transverse thrust minor - to various sources of
theoretical uncertainty: multiple parton interactions, parton showers, colour
(re)connections, and hadronization. The power of each observable to furnish
constraints on Monte Carlo models is illustrated by including comparisons
between several recent, and qualitatively different, PYTHIA 6 tunes, for pp
collisions at sqrt(s) = 900 GeV.Comment: 13 page
The reaction mechanism of metallo-beta-lactamases is tuned by the conformation of an active site mobile loop
Carbapenems are "last resort" β-lactam antibiotics used to treat serious and life-threatening health care-associated infections caused by multidrug-resistant Gram-negative bacteria. Unfortunately, the worldwide spread of genes coding for carbapenemases among these bacteria is threatening these life-saving drugs. Metallo-β-lactamases (MβLs) are the largest family of carbapenemases. These are Zn(II)-dependent hydrolases that are active against almost all β-lactam antibiotics. Their catalytic mechanism and the features driving substrate specificity have been matter of intense debate. The active sites of MβLs are flanked by two loops, one of which, loop L3, was shown to adopt different conformations upon substrate or inhibitor binding, and thus are expected to play a role in substrate recognition. However, the sequence heterogeneity observed in this loop in different MβLs has limited the generalizations about its role. Here, we report the engineering of different loops within the scaffold of the clinically relevant carbapenemase NDM-1. We found that the loop sequence dictates its conformation in the unbound form of the enzyme, eliciting different degrees of active-site exposure. However, these structural changes have a minor impact on the substrate profile. Instead, we report that the loop conformation determines the protonation rate of key reaction intermediates accumulated during the hydrolysis of different β-lactams in all MβLs. This study demonstrates the existence of a direct link between the conformation of this loop and the mechanistic features of the enzyme, bringing to light an unexplored function of active-site loops on MβLs.Fil: Palacios, Antonela Rocio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Mojica, María F.. Case Western Reserve University; Estados UnidosFil: Giannini, Estefanía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Taracila, Magdalena A.. Case Western Reserve University; Estados Unidos. Louis Stokes Veterans Affairs Medical Center; Estados UnidosFil: Bethel, Christopher R.. Louis Stokes Veterans Affairs Medical Center; Estados UnidosFil: Alzari, Pedro M.. Institut Pasteur de Paris; FranciaFil: Otero, Lisandro Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Klinke, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Llarrull, Leticia Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Bonomo, Robert A.. Case Western Reserve University; Estados UnidosFil: Vila, Alejandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin
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