2,240 research outputs found
Testimony of Jack West Before the Commission on the Future of Worker-Management Relations
Testimony_ASQC_081094.pdf: 115 downloads, before Oct. 1, 2020
Expression, purification and initial characterization of Halobacterium proline dehydrogenase
Abstract only availableNature recycles proline by converting it to glutamate. This 4-electron oxidation process is catalyzed by two catabolic enzymes, proline dehydrogenase (PRODH) and Δ1-pyrroline-5-carboxylate dehydrogenase (P5CDH). Inborn defects in PRODH and P5CDH result in the disorders hyperprolinemia I & II, respectively. These conditions are often associated with mental retardation, convulsions, and brain disorders. PRODH has also been implicated in schizophrenia susceptibility, cancer and P53-mediated apoptosis. Despite their importance in human health and disease, these enzymes have not been extensively studied. Thus, the goal of this research is to characterize the structure and function of PRODH. The work presented here focuses on a newly discovered homologue of PRODH found in archaea, which we identified by bioinformatics analysis of genome sequence data. Archaea are also genetically more closely related to eukaryotes than bacteria, so study of their proteins may provide insights into homologous eukaryotic enzymes. Archaea are some of the Earth's oldest life forms and are known for living in extreme environments. The PRODH researched here is from the Halobacterium (salt-loving), which can be found in places such as the Dead Sea and the Great Salt Lake. Preliminary results so far include testing the expression of Halobacterium PRODH, known as YusM, in two different E. coli expression systems, BL21(DE3)pLysS and Rosetta2. The latter strain was used to account for rare codon usage by Halobacterium. Parameters varied in these expression tests included time and temperature of induction as well as IPTG concentration. After expression, the cells were broken in a French pressure cell and the cell debris was pelleted with centrifugation. YusM was found to be largely associated with the cell pellet; therefore protein purification under denaturing conditions was investigated. The use of urea as a denaturing reagent has been successful for purifying YusM. Once the protein was renatured it showed improved kinetic activity. We believe the improved activity is due to disruption of improperly folded protein by the denaturant, followed by re-folding into the native, or near-native, state. Further studies will need to be done to determine the cause of misfolding in the E. coli cell.Stevens' Chemistry Progra
The massless supersymmetric ladder with L rungs
We show that in the massless N=1 supersymmetric Wess-Zumino theory it is
possible to devise a computational strategy by which the x-space calculation of
the ladder 4-point correlators can be carried out without introducing any
regularization. As an application we derive a representation valid at all loop
orders in terms of conformal invariant integrals. We obtain an explicit
expression of the 3-loop ladder diagram for collinear external points.Comment: LaTeX, 17 pages, 8 figure
Renormalization-Group Improved Effective Lagrangian for Interacting Theories in Curved Spacetime
A method for finding the renormalization group (RG) improved effective
Lagrangian for a massive interacting field theory in curved spacetime is
presented. As a particular example, the -theory is
considered and the RG improved effective Lagrangian is explicitly found up to
second order in the curvature tensors. As a further application, the
curvature-induced phase transitions are discussed for both the massive and the
massless versions of the theory. The problems which appear when calculating the
RG improved effective Lagrangian for gauge theories are discussed, taking as
example the asymptotically free SU(2) gauge model.Comment: 11 pages, LaTeX fil
Two-loop effective potential in quantum field theory in curved space-time
The method of the calculation of effective potential (in linear curvature
approximation and at any loop) in massless gauge theory in curved space- time
by the direct solution of RG equation is given.The closed expression for
two-loop effective potential is obtained.Two-loop effective potential in scalar
self-interacting theory is written explicitly.Some comments about it as well as
about two-loop effective potential in standard model are presented.Comment: 8page
Contribution of matter fields to the Gell-Mann-Low function for N=1 supersymmetric Yang-Mills theory, regularized by higher covariant derivatives
Contribution of matter fields to the Gell-Mann-Low function for N=1
supersymmetric Yang-Mills theory, regularized by higher covariant derivatives,
is obtained using Schwinger-Dyson equations and Slavnov-Tailor identities. A
possible deviation of the result from the corresponding contribution in the
exact Novikov, Shifman, Vainshtein and Zakharov -function is discussed.Comment: 20 pages, 4 figure
Automatic Calculation of supersymmetric Renormalization Group Equations and Self Energies
SARAH is a Mathematica package for studying supersymmetric models. It
calculates for a given model the masses, tadpole equations and all vertices at
tree-level. Those information can be used by \SARAH to write model files for
CalcHep/CompHep or FeynArts/FormCalc. In addition, the second version of SARAH
can derive the renormalization group equations for the gauge couplings,
parameters of the superpotential and soft-breaking parameters at one and
two-loop level. Furthermore, it calculates the one-loop self energies and the
one-loop corrections to the tadpoles. SARAH can handle all N=1 SUSY models
whose gauge sector is a direct product of SU(N) and U(1) gauge groups. The
particle content of the model can be an arbitrary number of chiral superfields
transforming as any irreducible representation with respect to the gauge
groups. To implement a new model, the user has just to define the gauge sector,
the particle, the superpotential and the field rotations to mass eigenstates.Comment: 32 pages, some typoes corrected, matches published versio
supersymmetry and the three loop anomalous dimension for the chiral superfield
We calculate the three loop anomalous dimension for a general
supersymmetric gauge theory. The result is used to probe the possible existence
of renormalisation invariant relationships between the Yukawa and gauge
couplings.Comment: 18 pages. Uses Harvmac. Revised version includes discussion of the
special case of the Wess-Zumino mode
Holomorphic Anomalies and the Nonrenormalization Theorem
It has been argued that the superpotential can be renormalized in the
presence of massless particles. Possible implications which have been
considered include the restoration of supersymmetry at higher loops or a shift
to a supersymmetric vacuum state. We argue that even in the presence of
massless particles, there are no new contributions to the superpotential at any
order in perturbation theory. This confirms the utility of the Wilsonian
superpotential for analyzing the moduli space of the low energy theory.Comment: 9 pages, LaTeX, 1 .ps figure, psfig.sty include
Non-renormalization theorems without supergraphs: The Wess-Zumino model
The non-renormalization theorems of chiral vertex functions are derived on
the basis of an algebraic analysis. The property, that the interaction vertex
is a second supersymmetry variation of a lower dimensional field monomial, is
used to relate chiral Green functions to superficially convergent Green
functions by extracting the two supersymmetry variations from an internal
vertex and transforming them to derivatives acting on external legs. The
analysis is valid in the massive as well as in the massless model and can be
performed irrespective of properties of the superpotential at vanishing
momentum.Comment: 20 pages, Latex, added acknowledgment
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