A comprehensive analysis of tree-level weak interaction processes at low energy is presented for the Randall-Sundrum (RS) model with SU(2)
L
× U(1)
Y
bulk gauge symmetry and brane-localized Higgs ...sector. The complete form of the effective weak Hamiltonian is obtained, which results from tree-level exchange of Kaluza-Klein (KK) gluons and photons, the
W
±
and
Z
0
bosons and their KK excitations, as well as the Higgs boson. Exact expressions are used for the bulk profiles of the various fields, and for the exchange of entire towers of KK gauge-boson states. A detailed phenomenological analysis is performed for potential new-physics effects in neutral-meson mixing and in rare decays of kaons and
B
mesons, including both inclusive and exclusive processes. We find that while the predictions for ∆
F
= 2 observables are rather model-independent, ∆
F
= 1 processes depend sensitively on the exact realizations of the electroweak gauge and the fermionic sector. In this context, we emphasize that the localization of the right-handed top quark in the extra dimension plays a crucial role in the case of rare
Z
0
-mediated decays, as it determines the relative size of left- to right-handed couplings. We also extend earlier studies of quark flavor-changing neutral currents by examining observables which up to now attracted little attention. These include
mixing,
B
→ τν
τ
,
B
→
X
s
(
K
*)
l
+
l
-
, ϵ′
K
/ϵ
K
,
,
,
, and
B
+
→ π
+
π
0
.
A fundamental characteristic of any biological invasion is the speed at which the geographic range of the population expands. This invasion speed is determined by both population growth and ...dispersal. We construct a discrete-time model for biological invasions that couples matrix population models (for population growth) with integrodifference equations (for dispersal). This model captures the important facts that individuals differ both in their vital rates and in their dispersal abilities, and that these differences are often determined by age, size, or developmental stage. For an important class of these equations, we demonstrate how to calculate the population's asymptotic invasion speed. We also derive formulas for the sensitivity and elasticity of the invasion speed to changes in demographic and dispersal parameters. These results are directly comparable to the familiar sensitivity and elasticity of population growth rate. We present illustrative examples, using published data on two plants: teasel (Dipsacus sylvestris) and Calathea ovandensis. Sensitivity and elasticity of invasion speed is highly correlated with the sensitivity and elasticity of population growth rate in both populations. We also find that, when dispersal contains both long- and short-distance components, it is the long-distance component that governs the invasion speed--even when long-distance dispersal is rare.
Neuronal apoptosis contributes to ischemic brain damage and neurodegenerative disorders. Key regulators of neuronal apoptosis are the transcription factor NF-κB and the MAP kinases p38/MAPK and JNK, ...which share a common upstream activator, the mitogen-activated protein kinase kinase kinase (MAP3K) TGFβ-activated kinase 1 (TAK1). Here we investigate the function of TAK1 in ischemia-induced neuronal apoptosis. In primary cortical neurons, TAK1 was activated by oxygen glucose deprivation (OGD), an in vitro model of cerebral ischemia. We found that short-term inhibition of TAK1 protected against OGD in vitro and reduced the infarct volume after middle cerebral artery occlusion in vivo. Prolonged inhibition or deletion of the TAK1 gene in neurons was, however, not protective. Short-term, but not prolonged inhibition of TAK1 interfered with the activation of p38/MAPK and JNK by OGD, the induction of the pro-oxidative genes Cox-2, Nox-2, and p40(phox), and the formation of superoxide. We found that prolonged TAK1 inhibition upregulated another MAP3K, apoptosis signal-regulating kinase-1, which is able to compensate for TAK1 inhibition. Our study demonstrates that TAK1 is a central target for short-term inhibition of key signaling pathways and neuroprotection in cerebral ischemia.
The electron-positron stage of the Future Circular Collider, FCC-ee, is a frontier factory for Higgs, top, electroweak, and flavour physics. It is designed to operate in a 100 km circular tunnel ...built at CERN, and will serve as the first step towards ≥100 TeV proton-proton collisions. In addition to an essential and unique Higgs program, it offers powerful opportunities to discover direct or indirect evidence of physics beyond the Standard Model. Direct searches for long-lived particles at FCC-ee could be particularly fertile in the high-luminosity
Z
run, where 5 × 10
12
Z
bosons are anticipated to be produced for the configuration with two interaction points. The high statistics of Higgs bosons,
W
bosons and top quarks in very clean experimental conditions could offer additional opportunities at other collision energies. Three physics cases producing long-lived signatures at FCC-ee are highlighted and studied in this paper: heavy neutral leptons (HNLs), axion-like particles (ALPs), and exotic decays of the Higgs boson. These searches motivate out-of-the-box optimization of experimental conditions and analysis techniques, which could lead to improvements in other physics searches.
The economics of decentralized methanation units require a reduced complexity of the gas cleanup of gasification-derived syngas resulting in higher concentrations of organic sulfur compounds, e.g. ...thiophene. The influence of thiophene as single compound as well as in combination with higher hydrocarbons on catalytic fixed bed methanation has been experimentally examined in a series of bench-scale tests with a commercial Ni catalyst. The change of activity of the catalytic fixed bed was studied by methanation under well-defined reference settings. For intermediate catalyst treatment the impurities thiophene, as major sulfur species unremoved by acid gas scrubbing, as well as ethene and naphthalene as major hydrocarbon species in syngas, have been chosen. In all experiments thiophene addition showed a slow but steadily-ongoing deactivation of the catalytic fixed bed with catalyst consumption varying from 0.6 to 1.7 gcatalyst/mmolC4H4S. Addition of 1.0vol.% ethene to the feedgas resulted in significant increase of the pressure drop over the fixed bed, whereas simultaneous addition of thiophene and ethene, as well as single or combined addition of naphthalene, did not cause any increase of the pressure drop. The results were compared to the sulfur passivated steam reforming but in case of methanation no similar mechanism is likely to exist.
The paper proposes a model-based feedforward control for the Czochralski crystal growth process. It completes the system for nonlinear model-based control presented by the authors in previous ...publications. From a system theoretical point of view such a feedforward control requires a dynamic lumped parameter model of the hydrodynamical-geometrical as well as of the thermal subsystem of the process. For the heater feedforward control one lacks the latter one with the necessary accuracy. A static approach circumventing this problem is presented here, based on a mathematical description regarding the most important qualitative dependencies between relative changes of manipulated and controlled variables during growth. In combination with feedback control, high precision tracking of the most important system variables, crystal diameter and crystal growth rate, is ensured. Additionally, a comprehensive discussion of the dependencies of the heater feedforward control on technological parameters, growth regimes and crystal shapes is given.
This paper presents a new approach for model-based control of the Czochralski process. The main idea is not to rely on a complex mathematical model of the overall process. Such a model usually ...suffers from many unknown parameters, boundary and initial conditions making the control system not robust. Instead, only those parts of the process are modeled the parameters of which are known with sufficient accuracy and the structure of which is sufficiently precise. From this model a nonlinear model-based controller is derived as the core of the proposed control system. It is used in combination with conventional PID controllers. Doing so, tracking of crystal diameter and growth rate trajectories is realized with a lot of model knowledge included in the control system. Thus, its performance is improved greatly. The usefulness of the approach is proven by several experimental results from growth of gallium-arsenide (GaAs) and indium-phosphide (InP) crystals.
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