2,886 research outputs found
A Higgs Conundrum with Vector Fermions
Many models of Beyond the Standard Model physics involve heavy colored
fermions. We study models where the new fermions have vector interactions and
examine the connection between electroweak precision measurements and Higgs
production. In particular, for parameters which are allowed by precision
measurements, we show that the gluon fusion Higgs cross section and the Higgs
decay branching ratios must be close to those predicted by the Standard Model.
The models we discuss thus represent scenarios with new physics which will be
extremely difficult to distinguish from the minimal Standard Model. We pay
particular attention to the decoupling properties of the vector fermions.Comment: 34 pages, 15 figures. Version accepted for publication in Phys. Rev.
the soluble d2d388 274 fragment of the urokinase receptor inhibits monocyte chemotaxis and integrin dependent cell adhesion
We have previously shown that chymotrypsin-cleaved soluble uPAR (D2D3 88-274 ) elicits migration of monocytic cells through interaction with FPRL-1, a G protein-coupled receptor that is homologous to the fMLP receptor. Here, we report that D2D3 88-274 also modulates the ability of monocytes to migrate in response to other chemokines. Pretreatment of monocytes with increasing amounts of D2D3 88-274 prevents cell migration in response to MCP-1, RANTES and fMLP. We demonstrate that D2D3 88-274 does not inhibit MCP-1 receptor binding, elicit CCR2 internalization and prevent MCP-1-induced intracellular Ca 2+ increase. Thus, CCR2 receptor desensitization cannot account for D2D3 88-274 -mediated inhibition of MCP-1-induced cell migration. Rather, we show that pretreatment of monocytes with D2D3 88-274 dramatically decreases chemokine-induced integrin-dependent rapid cell adhesion by interacting with FPRL-1. Together, our results indicate that chemokine-dependent cell migration can be regulated not only by homologous and heterologous receptor desensitization, but also by inhibition of integrin-dependent cell adhesion, an important step in cell transmigration
Ab initio simulations of Cu binding sites in the N-terminal region of PrP
The prion protein (PrP) binds Cu2+ ions in the octarepeat domain of the
N-terminal tail up to full occupancy at pH=7.4. Recent experiments show that
the HGGG octarepeat subdomain is responsible for holding the metal bound in a
square planar coordination. By using first principle ab initio molecular
dynamics simulations of the Car-Parrinello type, the Cu coordination mode to
the binding sites of the PrP octarepeat region is investigated. Simulations are
carried out for a number of structured binding sites. Results for the complexes
Cu(HGGGW)+(wat), Cu(HGGG) and the 2[Cu(HGGG)] dimer are presented. While the
presence of a Trp residue and a H2O molecule does not seem to affect the nature
of the Cu coordination, high stability of the bond between Cu and the amide
Nitrogens of deprotonated Gly's is confirmed in the case of the Cu(HGGG)
system. For the more interesting 2[Cu(HGGG)] dimer a dynamically entangled
arrangement of the two monomers, with intertwined N-Cu bonds, emerges. This
observation is consistent with the highly packed structure seen in experiments
at full Cu occupancy.Comment: 4 pages, conference proceedin
Caspase-independent programmed cell death triggers Ca2PO4 deposition in an in vitro model of nephrocalcinosis
We provide evidence of caspase-independent cell death triggering the calcification process in GDNF-silenced HK-2 cells
Symmetry defects in single-gyre, wind-driven oceanic systems
We explore some symmetry properties of the leading terms that constitute the solution describing the flow field structure in a wind-driven, bottom-dissipated ocean. Both the weakly non-linear and the highly non-linear regime are investigated. The main result is that the northward displacement and the westward intensification of the current system, which are typical of the subtropical gyres (for instance the North Atlantic Ocean), can be ascribed to an interplay between the symmetries of these terms. Moreover, a duality relationship allows us to relate the conclusions concerning one regime to the other
On the dynamics of quasi-geostrophic intergyre gyres
An important aspect of the present climatic change concerns the wind-stress anomalies over the ocean. It is possible to associate to them a special current field, which appears between the subtropical and the subpolar gyres and is known as intergyre gyre. In the present paper we investigate its dynamics by including recent models of stochastic wind field into the classical model of ocean circulation at the basin scale of Rhines and Young. In the framework of an analytical approach, developed at the geostrophic level of approximation, we explore the circulation patterns of this recently discovered characteristic of double gyres
Coulomb oscillations in three-layer graphene nanostructures
We present transport measurements on a tunable three-layer graphene single
electron transistor (SET). The device consists of an etched three-layer
graphene flake with two narrow constrictions separating the island from source
and drain contacts. Three lateral graphene gates are used to electrostatically
tune the device. An individual three-layer graphene constriction has been
investigated separately showing a transport gap near the charge neutrality
point. The graphene tunneling barriers show a strongly nonmonotonic coupling as
function of gate voltage indicating the presence of localized states in the
constrictions. We show Coulomb oscillations and Coulomb diamond measurements
proving the functionality of the graphene SET. A charging energy of meV is extracted.Comment: 10 pages, 6 figure
Managing the Lean–Agile Paradox in Complex Environments
The decision to incrementally improve existing processes and products or introduce breakthrough innovations depends on the context a company is facing. In situations where problems are known, it is better to incrementally improve, while in complex situations where problems are not known, a probe-sense-respond approach based on experimentation and the exploration of new solutions is preferable. Lean management adapts well to the first type of context, while agile management fits the second type of context. However, organizations must increasingly consider both approaches and become ambidextrous by introducing incremental improvements and breakthrough innovations simultaneously. This requires embracing the paradox between exploiting and exploring, adopting a new leadership mindset, and dual strategic, organizational, and behavioral models. This paper proposed a framework to implement lean and agile approaches simultaneously using the paradox theory to justify and manage this co-existence. This framework is threefold. First, managers need to differentiate between lean and agile, finding ways of keeping the two approaches separated. Second, lean and agile should be integrated so that synergies between the two approaches can be generated. Finally, managers need to achieve a dynamic equilibrium over time between lean and agile. Contributions to the theory and practice of this approach were discussed
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