1,447 research outputs found
Investment under ambiguity with the best and worst in mind
Recent literature on optimal investment has stressed the difference between the impact of risk and the impact of ambiguity - also called Knightian uncertainty - on investors' decisions. In this paper, we show that a decision maker's attitude towards ambiguity is similarly crucial for investment decisions. We capture the investor's individual ambiguity attitude by applying alpha-MEU preferences to a standard investment problem. We show that the presence of ambiguity often leads to an increase in the subjective project value, and entrepreneurs are more eager to invest. Thereby, our investment model helps to explain differences in investment behavior in situations which are objectively identical
Insights into the pre-initiation events of bacteriophage phi6 RNA-dependent RNA polymerase : towards the assembly of a productive binary complex
The RNA-dependent RNA polymerase (RdRP) of double-stranded RNA (dsRNA) viruses performs both RNA replication and transcription. In order to initiate RNA polymerization, viral RdRPs must be able to interact with the incoming 3 terminus of the template and position it, so that a productive binary complex is formed. Structural studies have revealed that RdRPs of dsRNA viruses that lack helicases have electrostatically charged areas on the polymerase surface, which might facilitate such interactions. In this study, structure-based mutagenesis, enzymatic assays and molecular mapping of bacteriophage 6 RdRP and its RNA were used to elucidate the roles of the negatively charged plough area on the polymerase surface, of the rim of the template tunnel and of the template specificity pocket that is key in the formation of the productive RNA-polymerase binary complex. The positively charged rim of the template tunnel has a significant role in the engagement of highly structured ssRNA molecules, whereas specific interactions further down in the template tunnel promote ssRNA entry to the catalytic site. Hence, we show that by aiding the formation of a stable binary complex with optimized RNA templates, the overall polymerization activity of the 6 RdRP can be greatly enhanced.The RNA-dependent RNA polymerase (RdRP) of double-stranded RNA (dsRNA) viruses performs both RNA replication and transcription. In order to initiate RNA polymerization, viral RdRPs must be able to interact with the incoming 3 terminus of the template and position it, so that a productive binary complex is formed. Structural studies have revealed that RdRPs of dsRNA viruses that lack helicases have electrostatically charged areas on the polymerase surface, which might facilitate such interactions. In this study, structure-based mutagenesis, enzymatic assays and molecular mapping of bacteriophage 6 RdRP and its RNA were used to elucidate the roles of the negatively charged plough area on the polymerase surface, of the rim of the template tunnel and of the template specificity pocket that is key in the formation of the productive RNA-polymerase binary complex. The positively charged rim of the template tunnel has a significant role in the engagement of highly structured ssRNA molecules, whereas specific interactions further down in the template tunnel promote ssRNA entry to the catalytic site. Hence, we show that by aiding the formation of a stable binary complex with optimized RNA templates, the overall polymerization activity of the 6 RdRP can be greatly enhanced.The RNA-dependent RNA polymerase (RdRP) of double-stranded RNA (dsRNA) viruses performs both RNA replication and transcription. In order to initiate RNA polymerization, viral RdRPs must be able to interact with the incoming 3 terminus of the template and position it, so that a productive binary complex is formed. Structural studies have revealed that RdRPs of dsRNA viruses that lack helicases have electrostatically charged areas on the polymerase surface, which might facilitate such interactions. In this study, structure-based mutagenesis, enzymatic assays and molecular mapping of bacteriophage 6 RdRP and its RNA were used to elucidate the roles of the negatively charged plough area on the polymerase surface, of the rim of the template tunnel and of the template specificity pocket that is key in the formation of the productive RNA-polymerase binary complex. The positively charged rim of the template tunnel has a significant role in the engagement of highly structured ssRNA molecules, whereas specific interactions further down in the template tunnel promote ssRNA entry to the catalytic site. Hence, we show that by aiding the formation of a stable binary complex with optimized RNA templates, the overall polymerization activity of the 6 RdRP can be greatly enhanced.Peer reviewe
Transverse Momentum and Rapidity Dependence of HBT Correlations in Au+Au Collisions at sqrt(s_NN) = 62.4 and 200 GeV
Two-particle correlations of identical charged pion pairs from Au+Au
collisions at sqrt(s_NN) = 62.4 and 200 GeV were measured by the PHOBOS
experiment at RHIC. Data for the 15% most central events were analyzed with
Bertsch-Pratt and Yano-Koonin-Podgoretskii parameterizations using pairs with
rapidities of 0.4 < y_{\pi\pi} < 1.3 and transverse momenta 0.1 < k_T < 1.4
GeV/c. The Bertsch-Pratt radii R_o and R_l decrease as a function of pair
transverse momentum, while R_s is consistent with a weaker dependence. R_o and
R_s are independent of collision energy, while R_l shows a slight increase. The
source rapidity y_{ykp} scales roughly with the pair rapidity y_{\pi\pi},
indicating strong dynamical correlations.Comment: 5 pages, 4 figures, 2 tables, submitted to Phys. Rev.
Landau theory applied to phase transitions in calcium orthotungstate and isostructural compounds
The pressure-driven tetragonal-to-monoclinic phase transition in CaWO4 and
related scheelite-structured orthotungstates is analysed in terms of
spontaneous strains. Based upon our previous high-pressure x-ray diffraction
results and the Landau theory, it is suggested that the
scheelite-to-fergusonite transition is of second order in nature.Comment: 14 pages, 3 figure
Charged antiparticle to particle ratios near midrapidity in p+p collisions at sqrt(s_NN)=200 GeV
The ratios of the yields of primary charged antiparticles to particles have
been obtained for pions, kaons, and protons near midrapidity for p+p collisions
at sqrt(s_NN) = 200 GeV. Ratios of =1.000 +/- 0.012 (stat.) +/- 0.019
(syst.), =0.93 +/- 0.05 (stat.) +/- 0.03 (syst.), and =0.85 +/-
0.04 (stat.) +/- 0.03 (syst.) have been measured. The reported values represent
the ratio of the yields averaged over the rapidity range of 0.1<y_{pi}<1.3 and
0<y_{K,p}<0.8, and for transverse momenta of 0.1<p_T^{pi,K}<1.0 GeV/c and
0.3<p_T^{p}<1.0 GeV/c. Within the uncertainties, all three ratios are
consistent with the values measured in d+Au collisions at the same energy. The
data are compared to results from other collision systems and energies.Comment: 3 pages, 2 figures, 1 table, submitted to Phys. Rev.
Energy dependence of elliptic flow over a large pseudorapidity range in Au+Au collisions at RHIC
This paper describes the measurement of the energy dependence of elliptic
flow for charged particles in Au+Au collisions using the PHOBOS detector at the
Relativistic Heavy Ion Collider (RHIC). Data taken at collision energies of
19.6, 62.4, 130 and 200 GeV are shown over a wide range in
pseudorapidity. These results, when plotted as a function of
, scale with approximate linearity throughout ,
implying no sharp changes in the dynamics of particle production as a function
of pseudorapidity or increasing beam energy.Comment: 5 pages, 4 figure
Forward-Backward Multiplicity Correlations in sqrt(s_NN) = 200 GeV Gold-Gold Collisions
Forward-backward correlations of charged-particle multiplicities in symmetric
bins in pseudorapidity are studied in order to gain insight into the underlying
correlation structure of particle production in Au+Au collisions. The PHOBOS
detector is used to measure integrated multiplicities in bins centered at eta,
defined within |eta|<3, and covering intervals Delta-eta. The variance
sigma^2_C of a suitably defined forward-backward asymmetry variable C is
calculated as a function of eta, Delta-eta, and centrality. It is found to be
sensitive to short range correlations, and the concept of "clustering'' is used
to interpret comparisons to phenomenological models.Comment: 5 Pages, 5 Figures, submitted to Physical Review C -- Rapid
Communication
Centrality dependence of charged hadron transverse momentum spectra in d+Au collisions at sqrt(s_NN) = 200 GeV
We have measured transverse momentum distributions of charged hadrons
produced in d+Au collisions at sqrt(s_NN) = 200 GeV. The spectra were obtained
for transverse momenta 0.25 < p_T < 6.0 GeV/c, in a pseudorapidity range of 0.2
< eta < 1.4 in the deuteron direction. The evolution of the spectra with
collision centrality is presented in comparison to p+pbarcollisions at the same
collision energy. With increasing centrality, the yield at high transverse
momenta increases more rapidly than the overall particle density, leading to a
strong modification of the spectral shape. This change in spectral shape is
qualitatively different from observations in Au+Au collisions at the same
energy. The results provide important information for discriminating between
different models for the suppression of high-p_T hadrons observed in Au+Au
collisions.Comment: 5 pages, 4 figures, submitted to PR
Centrality and pseudorapidity dependence of elliptic flow for charged hadrons in Au+Au collisions at sqrt(sNN) = 200 GeV
This paper describes the measurement of elliptic flow for charged particles
in Au+Au collisions at sqrt(sNN)=200 GeV using the PHOBOS detector at the
Relativistic Heavy Ion Collider (RHIC). The measured azimuthal anisotropy is
presented over a wide range of pseudorapidity for three broad collision
centrality classes for the first time at this energy. Two distinct methods of
extracting the flow signal were used in order to reduce systematic
uncertainties. The elliptic flow falls sharply with increasing eta at 200 GeV
for all the centralities studied, as observed for minimum-bias collisions at
sqrt(sNN)=130 GeV.Comment: Final published version: the most substantive change to the paper is
the inclusion of a complete description of how the errors from the hit-based
and track-based analyses are merged to produce the 90% C.L. errors quoted for
the combined results shown in Fig.
The Landscape of Particle Production: Results from PHOBOS
Recent results from the PHOBOS experiment at RHIC are presented, both from
Au+Au collisions from the 2001 run and p+p and d+Au collisions from 2003. The
centrality dependence of the total charged particle multiplicity in p+p and
d+Au show features, such as Npart-scaling and limiting fragmentation, similar
to p+A collisions at lower energies. Multiparticle physics in Au+Au is found to
be local in (pseudo)rapidity, both when observed by HBT correlations and by
forward-backward pseudorapidity correlations. The shape of elliptic flow in
Au+Au, measured over the full range of pseudorapidity, appears to have a very
weak centrality dependence. Identified particle ratios in d+Au reactions show
little difference between the shape of proton and anti-proton spectra, while
the absolute yields show an approximate m_T scaling.Comment: 8 Pages, 11 Figures, Plenary talk at Quark Matter 2004, Oakland, CA,
January 11-18, 200
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