2,103 research outputs found
Going with the Flow: Identifying a Single Commonality in Written and Performed Acting Theory
This study was designed to determine whether a single performance commonality could be determined to exist across styles of performance theory, and focused on investigating the experiential moment of performance. Identifying this commonality did not intend to codify the process or purpose of performance but to demonstrate the underlying human aspect of performance, irrespective of context or action, and give performers a starting point from which to approach a tradition radically different than the ones with which they are familiar. In his work, psychologist Mihaly Csikszentimihalyi describes the idea of flow, a merging of attention, awareness, and action which creates a holistic sensation that connects the body to its environment. This form of experience, it was predicted, would appear as an underlying commonality, regardless of the performance theory identifies. Information was gathered in two forms: first, theoretically, through the study of representative performance theories of differing styles; second, practically, through information gathered from professional performers. The elements of flow were found in both the styles used to represent the categories of performance theory and in evidence gathered from performers. Despite this, however, this particular study remains essentially inconclusive. Limited participation and structural flaws in the study limit the conclusiveness if the data. From the information gathered, a definite trend towards the common presence of flow can be identified, but further research remains necessary to conclusively state that it is the overarching commonality of performance theory. The strength of the results, however, indicates that a similar study with broader scope would produce its successful identification
Competition for hydrogen bond formation in the helix-coil transition and protein folding
The problem of the helix-coil transition of biopolymers in explicit solvents,
like water, with the ability for hydrogen bonding with solvent is addressed
analytically using a suitably modified version of the Generalized Model of
Polypeptide Chains. Besides the regular helix-coil transition, an additional
coil-helix or reentrant transition is also found at lower temperatures. The
reentrant transition arises due to competition between polymer-polymer and
polymer-water hydrogen bonds. The balance between the two types of hydrogen
bonding can be shifted to either direction through changes not only in
temperature, but also by pressure, mechanical force, osmotic stress or other
external influences. Both polypeptides and polynucleotides are considered
within a unified formalism. Our approach provides an explanation of the
experimental difficulty of observing the reentrant transition with pressure;
and underscores the advantage of pulling experiments for studies of DNA.
Results are discussed and compared with those reported in a number of recent
publications with which a significant level of agreement is obtained.Comment: 21 pages, 3 figures, submitted to Phys Rev
Statistical-mechanical lattice models for protein-DNA binding in chromatin
Statistical-mechanical lattice models for protein-DNA binding are well
established as a method to describe complex ligand binding equilibriums
measured in vitro with purified DNA and protein components. Recently, a new
field of applications has opened up for this approach since it has become
possible to experimentally quantify genome-wide protein occupancies in relation
to the DNA sequence. In particular, the organization of the eukaryotic genome
by histone proteins into a nucleoprotein complex termed chromatin has been
recognized as a key parameter that controls the access of transcription factors
to the DNA sequence. New approaches have to be developed to derive statistical
mechanical lattice descriptions of chromatin-associated protein-DNA
interactions. Here, we present the theoretical framework for lattice models of
histone-DNA interactions in chromatin and investigate the (competitive) DNA
binding of other chromosomal proteins and transcription factors. The results
have a number of applications for quantitative models for the regulation of
gene expression.Comment: 19 pages, 7 figures, accepted author manuscript, to appear in J.
Phys.: Cond. Mat
Alpha helix-coil phase transition: analysis of ab initio theory predictions
In the present paper we present results of calculations obtained with the use
of the theoretical method described in our preceding paper [1] and perform
detail analysis of alpha helix-random coil transition in alanine polypeptides
of different length. We have calculated the potential energy surfaces of
polypeptides with respect to their twisting degrees of freedom and construct a
parameter-free partition function of the polypeptide using the suggested method
[1]. From the build up partition function we derive various thermodynamical
characteristics for alanine polypeptides of different length as a function of
temperature. Thus, we analyze the temperature dependence of the heat capacity,
latent heat and helicity for alanine polypeptides consisting of 21, 30, 40, 50
and 100 amino acids. Alternatively, we have obtained same thermodynamical
characteristics from the use of molecular dynamics simulations and compared
them with the results of the new statistical mechanics approach. The comparison
proves the validity of the statistical mechanic approach and establishes its
accuracy.Comment: 34 pages, 12 figure
Ab initio theory of helix-coil phase transition
In this paper we suggest a theoretical method based on the statistical
mechanics for treating the alpha-helix-random coil transition in alanine
polypeptides. We consider this process as a first-order phase transition and
develop a theory which is free of model parameters and is based solely on
fundamental physical principles. It describes essential thermodynamical
properties of the system such as heat capacity, the phase transition
temperature and others from the analysis of the polypeptide potential energy
surface calculated as a function of two dihedral angles, responsible for the
polypeptide twisting. The suggested theory is general and with some
modification can be applied for the description of phase transitions in other
complex molecular systems (e.g. proteins, DNA, nanotubes, atomic clusters,
fullerenes).Comment: 24 pages, 3 figure
Renaissance of the ~1 TeV Fixed-Target Program
This document describes the physics potential of a new fixed-target program
based on a ~1 TeV proton source. Two proton sources are potentially available
in the future: the existing Tevatron at Fermilab, which can provide 800 GeV
protons for fixed-target physics, and a possible upgrade to the SPS at CERN,
called SPS+, which would produce 1 TeV protons on target. In this paper we use
an example Tevatron fixed-target program to illustrate the high discovery
potential possible in the charm and neutrino sectors. We highlight examples
which are either unique to the program or difficult to accomplish at other
venues.Comment: 31 pages, 11 figure
Sequence Effects on DNA Entropic Elasticity
DNA stretching experiments are usually interpreted using the worm-like chain
model; the persistence length A appearing in the model is then interpreted as
the elastic stiffness of the double helix. In fact the persistence length
obtained by this method is a combination of bend stiffness and intrinsic bend
effects reflecting sequence information, just as at zero stretching force. This
observation resolves the discrepancy between the value of A measured in these
experiments and the larger ``dynamic persistence length'' measured by other
means. On the other hand, the twist persistence length deduced from
torsionally-constrained stretching experiments suffers no such correction. Our
calculation is very simple and analytic; it applies to DNA and other polymers
with weak intrinsic disorder.Comment: LaTeX; postscript available at
http://dept.physics.upenn.edu/~nelson/index.shtm
Parton Distributions Working Group
The main focus of this working group was to investigate the different issues
associated with the development of quantitative tools to estimate parton
distribution functions uncertainties. In the conclusion, we introduce a
"Manifesto" that describes an optimal method for reporting data.Comment: Report of the Parton Distributions Working Group of the 'QCD and Weak
Boson Physics workshop in preparation for Run II at the Fermilab Tevatron'.
Co-Conveners: L. de Barbaro, S.A. Keller, S. Kuhlmann, H. Schellman, and
W.-K. Tun
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