1,122 research outputs found
Two-loop master integrals for the leading QCD corrections to the Higgs coupling to a pair and to the triple gauge couplings and
We compute the two-loop master integrals required for the leading QCD
corrections to the interaction vertex of a massive neutral boson , e.g.
or , with a pair of bosons, mediated by a quark
doublet composed of one massive and one massless flavor. All the external legs
are allowed to have arbitrary invariant masses. The Magnus exponential is
employed to identify a set of master integrals that, around space-time
dimensions, obey a canonical system of differential equations. The canonical
master integrals are given as a Taylor series in , up to
order four, with coefficients written as combination of Goncharov
polylogarithms, respectively up to weight four. In the context of the Standard
Model, our results are relevant for the mixed EW-QCD corrections to the Higgs
decay to a pair, as well as to the production channels obtained by
crossing, and to the triple gauge boson vertices and .Comment: 42 pages, 5 figures, 2 ancillary file
Do conformational changes contribute to the surface plasmon resonance signal?
Surface plasmon resonance (SPR)-based biosensors are widely used instruments
for characterizing molecular interactions. In theory the SPR signal depends
only on mass changes for interacting molecules of same chemical nature. Whether
conformational changes of interacting molecules also contribute to the SPR
signal is still a subject of lively debates. Works have been published claiming
that conformational changes were detected but all factors contributing to the
SPR signal were not carefully considered, in addition to often using no or
improper controls. In the present work we used a very well-characterized
oligonucleotide, the thrombin-binding DNA aptamer (TBA), which upon binding of
potassium ions folds into a two G-tetrad antiparallel G-quadruplex structure.
All terms contributing to the maximal expected SPR response, Rmax, in
particular the refractive index increment, RII, of both partners and the
fraction of immobilized TBA target available, ca, were experimentally assessed.
The resulting Rmax was then compared to the maximal experimental SPR response
for potassium ions binding to TBA using appropriate controls. Regardless how
the RIIs were measured, by SPR or refractometry, and how much TBA available for
interacting with potassium ions was considered, the theoretical and the
experimental SPR responses never matched, the former being always lower than
the latter. Using a straightforward experimental model system and by thoroughly
taking into account all contributing factors we therefore conclude that
conformational changes can indeed contribute to the measured SPR signal
Master integrals for the NNLO virtual corrections to scattering in QCD: the non-planar graphs
We complete the analytic evaluation of the master integrals for the two-loop
non-planar box diagrams contributing to the top-pair production in the
quark-initiated channel, at next-to-next-to-leading order in QCD. The integrals
are determined from their differential equations, which are cast into a
canonical form using the Magnus exponential. The analytic expressions of the
Laurent series coefficients of the integrals are expressed as combinations of
generalized polylogarithms, which we validate with several numerical checks. We
discuss the analytic continuation of the planar and the non-planar master
integrals, which contribute to in QCD, as well as
to the companion QED scattering processes and .Comment: 1+26 pages, 4 figures, 1 table, 3 ancillary files. v2: references
added, text partly reworded, results unmodifie
Investigação de triatomÃneos nos municÃpios de Rio Grande, Santa Vitória do Palmar e Jaguarão
Investigação de triatomÃneos nos municÃpios de Rio Grande,Santa Vitória do Palmar e Jaguarã
Serine/threonine kinase 3-phosphoinositide-dependent protein kinase-1 (PDK1) as a key regulator of cell migration and cancer dissemination
Dissecting the cellular signaling that governs the motility of eukaryotic cells is one of the fundamental tasks of modern cell biology, not only because of the large number of physiological processes in which cell migration is crucial, but even more so because of the pathological ones, in particular tumor invasion and metastasis. Cell migration requires the coordination of at least four major processes: polarization of intracellular signaling, regulation of the actin cytoskeleton and membrane extension, focal adhesion and integrin signaling and contractile forces generation and rear retraction. Among the molecular components involved in the regulation of locomotion, the phosphatidylinositol-3-kinase (PI3K) pathway has been shown to exert fundamental role. A pivotal node of such pathway is represented by the serine/threonine kinase 3-phosphoinositide-dependent protein kinase-1 (PDPK1 or PDK1). PDK1, and the majority of its substrates, belong to the AGC family of kinases (related to cAMP-dependent protein kinase 1, cyclic Guanosine monophosphate-dependent protein kinase and protein kinase C), and control a plethora of cellular processes, downstream either to PI3K or to other pathways, such as RAS GTPase-MAPK (mitogen-activated protein kinase). Interestingly, PDK1 has been demonstrated to be crucial for the regulation of each step of cell migration, by activating several proteins such as protein kinase B/Akt (PKB/Akt), myotonic dystrophy-related CDC42-binding kinases alpha (MRCKα), Rho associated coiled-coil containing protein kinase 1 (ROCK1), phospholipase C gamma 1 (PLCγ1) and β3 integrin. Moreover, PDK1 regulates cancer cell invasion as well, thus representing a possible target to prevent cancer metastasis in human patients. The aim of this review is to summarize the various mechanisms by which PDK1 controls the cell migration process, from cell polarization to actin cytoskeleton and focal adhesion regulation, and finally, to discuss the evidence supporting a role for PDK1 in cancer cell invasion and dissemination
Master integrals for the NNLO virtual corrections to scattering in QED: the non-planar graphs
We evaluate the master integrals for the two-loop non-planar box-diagrams
contributing to the elastic scattering of muons and electrons at
next-to-next-to-leading order in QED. We adopt the method of differential
equations and the Magnus exponential to determine a canonical set of integrals,
finally expressed as a Taylor series around four space-time dimensions, with
coefficients written as a combination of generalised polylogarithms. The
electron is treated as massless, while we retain full dependence on the muon
mass. The considered integrals are also relevant for crossing-related
processes, such as di-muon production at colliders, as well as for the
QCD corrections to top-pair production at hadron colliders. In particular, our
results, together with the planar master integrals recently computed, represent
the complete set of functions needed for the evaluation of the photonic
two-loop virtual next-to-next-to-leading order QED corrections to and .Comment: published version, 33 pages, 3 figures, 1 ancillary file. arXiv admin
note: text overlap with arXiv:1709.0743
Principal Eigenvalue of Mixed Problem for the Fractional Laplacian: Moving the Boundary Conditions
We analyze the behavior of the eigenvalues of the following non local mixed
problem \left\{ \begin{array}{rcll} (-\Delta)^{s} u &=& \lambda_1(D) \ u
&\inn\Omega,\\ u&=&0&\inn D,\\ \mathcal{N}_{s}u&=&0&\inn N. \end{array}\right
Our goal is to construct different sequences of problems by modifying the
configuration of the sets and , and to provide sufficient and necessary
conditions on the size and the location of these sets in order to obtain
sequences of eigenvalues that in the limit recover the eigenvalues of the
Dirichlet or Neumann problem. We will see that the non locality plays a crucial
role here, since the sets and can have infinite measure, a phenomenon
that does not appear in the local case (see for example \cite{D,D2,CP})
Systematic screening of LNA/2′-O-methyl chimeric derivatives of a TAR RNA aptamer
AbstractWe synthesized and evaluated by surface plasmon resonance 64 LNA/2′-O-methyl sequences corresponding to all possible combinations of such residues in a kissing aptamer loop complementary to the 6-nt loop of the TAR element of HIV-1. Three combinations of LNA/2′-O-methyl nucleoside analogues where one or two LNA units are located on the 3′ side of the aptamer loop display an affinity for TAR below 1nM, i.e. one order of magnitude higher than the parent RNA aptamer. One of these combinations inhibits the TAR-dependent luciferase expression in a cell assay
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