30,924 research outputs found
Facilitation of polymer looping and giant polymer diffusivity in crowded solutions of active particles
We study the dynamics of polymer chains in a bath of self-propelled particles
(SPP) by extensive Langevin dynamics simulations in a two dimensional system.
Specifically, we analyse the polymer looping properties versus the SPP activity
and investigate how the presence of the active particles alters the chain
conformational statistics. We find that SPPs tend to extend flexible polymer
chains while they rather compactify stiffer semiflexible polymers, in agreement
with previous results. Here we show that larger activities of SPPs yield a
higher effective temperature of the bath and thus facilitate looping kinetics
of a passive polymer chain. We explicitly compute the looping probability and
looping time in a wide range of the model parameters. We also analyse the
motion of a monomeric tracer particle and the polymer's centre of mass in the
presence of the active particles in terms of the time averaged mean squared
displacement, revealing a giant diffusivity enhancement for the polymer chain
via SPP pooling. Our results are applicable to rationalising the dimensions and
looping kinetics of biopolymers at constantly fluctuating and often actively
driven conditions inside biological cells or suspensions of active colloidal
particles or bacteria cells.Comment: 15 pages, 9 figures, IOPLaTe
A long run structural macroeconometric model of the UK
A new modelling strategy is introduced which provides a practical approach to incorporating long- run structural relationships, suggested by economic theory, in an otherwise unrestricted VAR model. The strategy is applied in the construction of a small quarterly macroeconometric model of the UK, estimated over the period 1965q1-1995q4 in eight core variables: domestic and foreign outputs, domestic and foreign prices (both measured relative to oil prices), the nominal effective exchange rate, nominal domestic and foreign interest rates and real money balances. The aim is to develop a core model with a transparent and theoretically coherent foundation. Tests of restrictions on the long-run relations of the model are presented and the dynamic properties of the model are discussed.Long-Run Structural VAR, A Core UK Model, Macroeconomic Modelling, Persistence Profiles
Forecast Uncertainties in Macroeconomics Modelling: An Application to the UK Economy
This paper argues that probability forecasts convey information on the uncertainties that surround marco-economic forecasts in a manner which is straightforward and which is preferable to other alternatives, including the use of confidence intervals. Probability forecasts relating to UK output growth and inflation, obtained using a small macro-econometric model, are presented. We discuss in detail the probability that inflation will fall within the Bank of England's target range and that recession will be avoided, both as separate single events and jointly. The probability forecasts are also used to provide insights on the interrelatedness of output growth and inflation outcomes at different horizons.Probability Forecasting, Long Run Structural VARs, Macroeconometric Modelling, Forecast Evaluation, Probability Forecasts of Inflation and Output Growth
Sine-Gordon Soliton on a Cnoidal Wave Background
The method of Darboux transformation, which is applied on cnoidal wave
solutions of the sine-Gordon equation, gives solitons moving on a cnoidal wave
background. Interesting characteristics of the solution, i.e., the velocity of
solitons and the shift of crests of cnoidal waves along a soliton, are
calculated. Solutions are classified into three types (Type-1A, Type-1B,
Type-2) according to their apparent distinct properties.Comment: 11 pages, 5 figures, Contents change
Faddeev calculation of pentaquark in the Nambu-Jona-Lasinio model-based diquark picture
A Bethe-Salpeter-Faddeev (BSF) calculation is performed for the pentaquark
in the diquark picture of Jaffe and Wilczek in which is a
diquark-diquark- three-body system. Nambu-Jona-Lasinio (NJL) model is
used to calculate the lowest order diagrams in the two-body scatterings of
and . With the use of coupling constants determined from the
meson sector, we find that interaction is attractive in s-wave
while interaction is repulsive in p-wave. With only the lowest three-body
channel considered, we do not find a bound pentaquark state.
Instead, a bound pentaquark with is obtained with a
unphysically strong vector mesonic coupling constants.Comment: 22 pages, 11 figures, accepted version in Phys. Rev. C. Summary of
main changes/corrections: 1. "which only holds at tree level" below the eq.
(23) is added. 2. In the last paragraph of p.23 we added a remark that the
coupling constant obtained from Lambda mass is different from the estimate as
obtained from the meson spectru
Specific Rab GTPase-activating proteins define the Shiga toxin and epidermal growth factor uptake pathways
Rab family guanosine triphosphatases (GTPases) together with their regulators define specific pathways of membrane traffic within eukaryotic cells. In this study, we have investigated which Rab GTPase-activating proteins (GAPs) can interfere with the trafficking of Shiga toxin from the cell surface to the Golgi apparatus and studied transport of the epidermal growth factor (EGF) from the cell surface to endosomes. This screen identifies 6 (EVI5, RN-tre/USP6NL, TBC1D10A–C, and TBC1D17) of 39 predicted human Rab GAPs as specific regulators of Shiga toxin but not EGF uptake. We show that Rab43 is the target of RN-tre and is required for Shiga toxin uptake. In contrast, RabGAP-5, a Rab5 GAP, was unique among the GAPs tested and reduced the uptake of EGF but not Shiga toxin. These results suggest that Shiga toxin trafficking to the Golgi is a multistep process controlled by several Rab GAPs and their target Rabs and that this process is discrete from ligand-induced EGF receptor trafficking
Observation of Conduction Band Satellite of Ni Metal by 3p-3d Resonant Inverse Photoemission Study
Resonant inverse photoemission spectra of Ni metal have been obtained across
the Ni 3 absorption edge. The intensity of Ni 3 band just above Fermi
edge shows asymmetric Fano-like resonance. Satellite structures are found at
about 2.5 and 4.2 eV above Fermi edge, which show resonant enhancement at the
absorption edge. The satellite structures are due to a many-body configuration
interaction and confirms the existence of 3 configuration in the ground
state of Ni metal.Comment: 4 pages, 3 figures, submitted to Physical Review Letter
Resonant pairing between Fermions with unequal masses
We study the pairing between Fermions of different masses, especially at the
unitary limit. At equal populations, the thermodynamic properties are identical
with the equal mass case provided an appropriate rescaling is made. At unequal
populations, for sufficiently light majority species, the system does not phase
separate. For sufficiently heavy majority species, the phase separated normal
phase have a density larger than that of the superfluid. For atoms in harmonic
traps, the density profiles for unequal mass Fermions can be drastically
different from their equal-mass counterparts.Comment: 10 pages, 4 figure
- …