971 research outputs found
Redefining B-twisted topological sigma models
A recently proposed variation on the usual procedure to perform the
topological B-twist in rigid models is applied to the case of the model on a K\"ahler manifold. This leads to an alternative description of
Witten's topological model, which allows for a proper BRST
interpretation and ghost number assignement. We also show that the auxiliary
fields, which are responsible for the off shell closure of the algebra,
play an important role in our construction.Comment: one reference adde
Overview of Biologically Active Nucleoside Phosphonates
The use of the phosphonate motif featuring a carbon-phosphorous bond as bioisosteric replacement of the labile PâO bond is widely recognized as an attractive structural concept in different areas of medicinal chemistry, since it addresses the very fundamental principles of enzymatic stability and minimized metabolic activation. This review discusses the most influential successes in drug design with special emphasis on nucleoside phosphonates and their prodrugs as antiviral and cancer treatment agents. A description of structurally related analogs able to interfere with the transmission of other infectious diseases caused by pathogens like bacteria and parasites will then follow. Finally, molecules acting as agonists/antagonists of P2X and P2Y receptors along with nucleotidase inhibitors will also be covered. This review aims to guide readers through the fundamentals of nucleoside phosphonate therapeutics in order to inspire the future design of molecules to target infections that are refractory to currently available therapeutic options
On the nature of fermion-monopole supersymmetry
It is shown that the generator of the nonstandard fermion-monopole
supersymmetry uncovered by De Jonghe, Macfarlane, Peeters and van Holten, and
the generator of its standard N=1/2 supersymmetry have to be supplemented by
their product operator to be treated as independent supercharge. As a result,
the fermion-monopole system possesses the nonlinear N=3/2 supersymmetry having
the nature of the 3D spin-1/2 free particle's supersymmetry generated by the
supercharges represented in a scalar form. Analyzing the supercharges'
structure, we trace how under reduction of the fermion-monopole system to the
spherical geometry the nonlinear N=3/2 superalgebra comprising the Hamiltonian
and the total angular momentum as even generators is transformed into the
standard linear N=1 superalgebra with the Hamiltonian to be the unique even
generator.Comment: 8 pages, minor extension of concluding comment
The regularized BRST Jacobian of pure Yang-Mills theory
The Jacobian for infinitesimal BRST transformations of path integrals for
pure Yang-Mills theory, viewed as a matrix \unity +\Delta J in the space of
Yang-Mills fields and (anti)ghosts, contains off-diagonal terms. Naively, the
trace of vanishes, being proportional to the trace of the structure
constants. However, the consistent regulator \cR, constructed from a general
method, also contains off-diagonal terms. An explicit computation demonstrates
that the regularized Jacobian Tr\ \Delta J\exp -\cR /M^2 for is the variation of a local counterterm, which we give. This is a
direct proof at the level of path integrals that there is no BRST anomaly.Comment: 12 pages, latex, CERN-TH.6541/92, KUL-TF-92/2
An alternative BRST operator for topological Landau-Ginzburg models
We propose a new BRST operator for the B-twist of N=2 Landau-Ginzburg (LG) models. It solves the problem of the fractional ghost numbers of Vafa's old BRST operator and shows how the model is obtained by gauge fixing a zero action. An essential role is played by the anti-BRST operator,which is given by one of the supersymmetries of the N=2 algebra. Its presence is needed in proving that the model is indeed a topological field theory. The space of physical observables, defined by taking the anti-BRST cohomology in the BRST cohomology groups, is unchanged
Simplifications in Lagrangian BV quantization exemplified by the anomalies of chiral gravity
The Batalin--Vilkovisky (BV) formalism is a useful framework to study gauge
theories. We summarize a simple procedure to find a a gauge--fixed action in
this language and a way to obtain one--loop anomalies. Calculations involving
the antifields can be greatly simplified by using a theorem on the antibracket
cohomology. The latter is based on properties of a `Koszul--Tate differential',
namely its acyclicity and nilpotency. We present a new proof for this
acyclicity, respecting locality and covariance of the theory. This theorem then
implies that consistent higher ghost terms in various expressions exist, and it
avoids tedious calculations.
This is illustrated in chiral gravity. We compute the one--loop anomaly
without terms of negative ghost number. Then the mentioned theorem and the
consistency condition imply that the full anomaly is determined up to local
counterterms. Finally we show how to implement background charges into the BV
language in order to cancel the anomaly with the appropriate counterterms.
Again we use the theorem to simplify the calculations, which agree with
previous results.Comment: 45 page
Multisystem proteinopathy due to a homozygous p.Arg159His VCP mutation : a tale of the unexpected
ObjectiveTo assess the clinical, radiologic, myopathologic, and proteomic findings in a patient manifesting a multisystem proteinopathy due to a homozygous valosin-containing protein gene (VCP) mutation previously reported to be pathogenic in the heterozygous state.MethodsWe studied a 36-year-old male index patient and his father, both presenting with progressive limb-girdle weakness. Muscle involvement was assessed by MRI and muscle biopsies. We performed whole-exome sequencing and Sanger sequencing for segregation analysis of the identified p.Arg159His VCP mutation. To dissect biological disease signatures, we applied state-of-the-art quantitative proteomics on muscle tissue of the index case, his father, 3 additional patients with VCP-related myopathy, and 3 control individuals.ResultsThe index patient, homozygous for the known p.Arg159His mutation in VCP, manifested a typical VCP-related myopathy phenotype, although with a markedly high creatine kinase value and a relatively early disease onset, and Paget disease of bone. The father exhibited a myopathy phenotype and discrete parkinsonism, and multiple deceased family members on the maternal side of the pedigree displayed a dementia, parkinsonism, or myopathy phenotype. Bioinformatic analysis of quantitative proteomic data revealed the degenerative nature of the disease, with evidence suggesting selective failure of muscle regeneration and stress granule dyshomeostasis.ConclusionWe report a patient showing a multisystem proteinopathy due to a homozygous VCP mutation. The patient manifests a severe phenotype, yet fundamental disease characteristics are preserved. Proteomic findings provide further insights into VCP-related pathomechanisms
Construction of topological field theories using BV
We discuss in detail the construction of topological field theories using the
Batalin--Vilkovisky (BV) quantisation scheme. By carefully examining the
dependence of the antibracket on an external metric, we show that
differentiating with respect to the metric and the BRST charge do not commute
in general. We introduce the energy momentum tensor in this scheme and show
that it is BRST invariant, both for the classical and quantum BRST operators.
It is antifield dependent, guaranteeing gauge independence. For topological
field theories, this energy momentum has to be quantum BRST exact. This leads
to conditions at each order in . As an example of this procedure, we
consider topological Yang--Mills theory. We show how the reducible set of
symmetries used in topological Yang--Mills can be recovered by means of trivial
systems and canonical transformations. Self duality of the antighosts is
properly treated by introducing an infinite tower of auxiliary fields. Finally,
it is shown that the full energy momentum tensor is classically BRST exact in
the antibracket sense.Comment: 15
Dose-effect relations in time-limited combined psycho-pharmacological treatment for depression
BACKGROUND: A limited number of psychotherapy sessions in combination with medication is preferable to pharmacotherapy only in the treatment of ambulatory patients with major depression. Whether there is a relation between the number of sessions and the efficacy of the treatment is uncertain. METHOD: Randomized clinical trial comparing two treatment conditions in outpatients with major depression. All patients studied had a baseline score of at least 14 points on the 17-item Hamilton Depression Rating Scale. The two conditions consist of 8-session or 16-session Short Psychodynamic Supportive Psychotherapy, both in combination with pharmacotherapy. Efficacy was assessed using the 17-item HDRS, the CGI of Severity and of Improvement, the depression subscale of the SCL-90 and the Quality of Life Depression Scale. RESULTS: The rate of change would seem to indicate that eight sessions are preferable for both moderately and severely depressed patients, although the results converged again at the end. Furthermore, in terms of satisfaction with the number of sessions and drop-out percentages during treatment, no differences were found between the conditions. CONCLUSION: In the light of the outcome analysis (faster remission after fewer sessions), a short version of the psychotherapy treatment in a combined course of treatment seems to be justifie
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