303 research outputs found
Relevant Deformations in Open String Field Theory: a Simple Solution for Lumps
We propose a remarkably simple solution of cubic open string field theory
which describes inhomogeneous tachyon condensation. The solution is in
one-to-one correspondence with the IR fixed point of the RG-flow generated in
the two--dimensional world-sheet theory by integrating a relevant operator with
mild enough OPE on the boundary. It is shown how the closed string overlap
correctly captures the shift in the closed string one point function between
the UV and the IR limits of the flow. Examples of lumps in non-compact and
compact transverse directions are given.Comment: 45 pages. v2: typos and minor improvements. v3: submitted to jhe
Non-simply-laced Lie algebras via F theory strings
In order to describe the appearance in F theory of the non--simply--laced Lie
algebras, we use the representation of symmetry enhancements by means of string
junctions. After an introduction to the techniques used to describe symmetry
enhancement, that is algebraic geometry, BPS states analysis and string
junctions, we concentrate on the latter. We give an explicit description of the
folding of D_{2n} to B_n of the folding of E_6 to F_4 and that of D_4 to G_2 in
terms of junctions and Jordan strings. We also discuss the case of C_n, but we
are unable in this case to provide a string interpretation.Comment: 24 pages, 3 figure
Mutation Symmetries in BPS Quiver Theories: Building the BPS Spectra
We study the basic features of BPS quiver mutations in 4D
supersymmetric quantum field theory with gauge symmetries.\ We show,
for these gauge symmetries, that there is an isotropy group
associated to a set of quiver mutations capturing
information about the BPS spectra. In the strong coupling limit, it is shown
that BPS chambers correspond to finite and closed groupoid orbits with an
isotropy symmetry group isomorphic to the discrete
dihedral groups contained in Coxeter with the
Coxeter number of G. These isotropy symmetries allow to determine the BPS
spectrum of the strong coupling chamber; and give another way to count the
total number of BPS and anti-BPS states of gauge theories. We
also build the matrix realization of these mutation groups from which we read directly the electric-magnetic
charges of the BPS and anti-BPS states of QFT as well as
their matrix intersections. We study as well the quiver mutation symmetries in
the weak coupling limit and give their links with infinite Coxeter groups. We
show amongst others that is contained in
; and isomorphic to the infinite Coxeter
. Other issues such as building
and are also
studied.Comment: LaTeX, 98 pages, 18 figures, Appendix I on groupoids adde
Rapid generation of endogenously driven transcriptional reporters in cells through CRISPR/Cas9
CRISPR/Cas9 technologies have been employed for genome editing to achieve gene knockouts and knock-ins in somatic cells. Similarly, certain endogenous genes have been tagged with fluorescent proteins. Often, the detection of tagged proteins requires high expression and sophisticated tools such as confocal microscopy and flow cytometry. Therefore, a simple, sensitive and robust transcriptional reporter system driven by endogenous promoter for studies into transcriptional regulation is desirable. We report a CRISPR/Cas9-based methodology for rapidly integrating a firefly luciferase gene in somatic cells under the control of endogenous promoter, using the TGFβ-responsive gene PAI-1. Our strategy employed a polycistronic cassette containing a non-fused GFP protein to ensure the detection of transgene delivery and rapid isolation of positive clones. We demonstrate that firefly luciferase cDNA can be efficiently delivered downstream of the promoter of the TGFβ-responsive gene PAI-1. Using chemical and genetic regulators of TGFβ signalling, we show that it mimics the transcriptional regulation of endogenous PAI-1 expression. Our unique approach has the potential to expedite studies on transcription of any gene in the context of its native chromatin landscape in somatic cells, allowing for robust high-throughput chemical and genetic screens
Comments on Lumps from RG flows
In this note we investigate the proposal of Ellwood and one of the authors et
al. to construct a string field theory solution describing the endpoint of an
RG flow from a reference BCFT to a target BCFT*. We show that the proposed
class of solutions suffers from an anomaly in the equations of motion.
Nevertheless, the gauge invariant action exactly reproduces the expected shift
in energy.Comment: 30 pages, 1 eps figure. V2: 40 pages 3 figures, presentation
expanded, energy and closed string tadpole computations extended to more
general class of solution
Back reaction, covariant anomaly and effective action
In the presence of back reaction, we first produce the one-loop corrections
for the event horizon and Hawking temperature of the Reissner-Nordstr\"om black
hole. Then, based on the covariant anomaly cancelation method and the effective
action technique, the modified expressions for the fluxes of gauge current and
energy momentum tensor, due to the effect of back reaction, are obtained. The
results are consistent with the Hawking fluxes of a (1+1)-dimensional blackbody
at the temperature with quantum corrections, thus confirming the robustness of
the covariant anomaly cancelation method and the effective action technique for
black holes with back reaction.Comment: 17 page
Tate Form and Weak Coupling Limits in F-theory
We consider the weak coupling limit of F-theory in the presence of
non-Abelian gauge groups implemented using the traditional ansatz coming from
Tate's algorithm. We classify the types of singularities that could appear in
the weak coupling limit and explain their resolution. In particular, the weak
coupling limit of SU(n) gauge groups leads to an orientifold theory which
suffers from conifold singulaties that do not admit a crepant resolution
compatible with the orientifold involution. We present a simple resolution to
this problem by introducing a new weak coupling regime that admits
singularities compatible with both a crepant resolution and an orientifold
symmetry. We also comment on possible applications of the new limit to model
building. We finally discuss other unexpected phenomena as for example the
existence of several non-equivalent directions to flow from strong to weak
coupling leading to different gauge groups.Comment: 34 page
Connecting Solutions in Open String Field Theory with Singular Gauge Transformations
We show that any pair of classical solutions of open string field theory can
be related by a formal gauge transformation defined by a gauge parameter
without an inverse. We investigate how this observation can be used to
construct new solutions. We find that a choice of gauge parameter consistently
generates a new solution only if the BRST charge maps the image of into
itself. When this occurs, we argue that naturally defines a star algebra
projector which describes a surface of string connecting the boundary conformal
field theories of the classical solutions related by . We also note that
singular gauge transformations give the solution space of open string field
theory the structure of a category, and we comment on the physical
interpretation of this observation.Comment: V2: minor improvements, added citation
Population-based incidence of Type 2 diabetes and its associated risk factors: results from a six-year cohort study in Iran
<p>Abstract</p> <p>Background</p> <p>The Middle East is estimated to have the largest increase in prevalence of diabetes by 2030; yet there is lack of published data on the incidence of Type 2 diabetes in this region. This study aimed to estimate Type 2 diabetes incidence and its associated risk factors in an Iranian urban population.</p> <p>Methods</p> <p>Among 3307 non-diabetics ≥ 20 years (mean age 42 ± 13 years, 42% males), glucose tolerance test was performed at baseline in 1999–2001 and at two consecutive phases in 2001–2005 and 2005–2008. Diabetes and glucose tolerance status were defined according to the ADA 1997 criteria. Logistic regression was used to determine the independent variables associated with incident diabetes and their odds ratios (OR).</p> <p>Results</p> <p>After median follow-up of 6 years, 237 new cases of diabetes were ascertained corresponding to an age and sex standardized cumulative incidence of 6.4% (95%CI: 5.6–7.2) and incidence rate of 10.6 (9.2–12.1) per 1000 person years. Besides classical diabetes risk factors, female sex and low education level significantly increased risk of diabetes in age adjusted models. In full model, the independent predictors were age [OR, 95%CI: 1.2 (1.1–1.3)], family history of diabetes [1.8 (1.3–2.5)], body mass index ≥ 30 kg/m<sup>2 </sup>[2.3 (1.5–3.6)], abdominal obesity [1.9 (1.4–2.6)], high triglyceride [1.4 (1.1–1.9)], Isolated impaired fasting glucose (IFG) [7.4 (3.6–15.0)], Isolated impaired glucose tolerance (IGT) [5.9 (4.2–8.4)] and combined IFG and IGT [42.2 (23.8–74.9)].</p> <p>Conclusion</p> <p>More than 1% of the Iranian urban population older than 20 years develops Type 2 diabetes each year. Combination of IFG and IGT was the strongest predictor of incident diabetes among the modifiable risk factors.</p
Level truncation analysis of regularized identity based solutions
We evaluate the vacuum energy of regularized identity based solutions through
level truncation computations in open bosonic string field theory. We show that
the level truncated solutions bring a value of the vacuum energy expected for
the tachyon vacuum in agreement with Sen's first conjecture.Comment: 22 pages, comments added, one table adde
- …