3,490 research outputs found
The Recent Brazilian Disinflation Process and Costs
This work revisits the recent disinflation process in Brazil and finds that solely the agents' perception that a policy rupture could occur is capable of triggering a change in the way firms and households used to behave in their pricing and consuming decisions. This change was captured by structural breaks in the parameters of a generalized hybrid Phillips curve, following the 2002 inflation shock. The paper also shows that such parameter changes led to an increase in the disinflation cost evidenced by a free market inflation gain that would have been observed should the coefficients on the Phillips curve have not changed. The paper finds that, maintaining the occurred paths for interest rates, output gap, nominal exchange rates, administered price inflation and exogenous shocks, the free market inflation would have been significantly lower in the absence of such structural break in the underlying inflation process, since mid 2002.
Collider Detection of Dark Matter Electromagnetic Anapole Moments
Dark matter that interacts with the Standard Model by exchanging photons
through higher multipole interactions occurs in a wide range of both strongly
as well as weakly coupled hidden sector models. We study the collider detection
prospects of these candidates, with a focus on Majorana dark matter that
couples through the anapole moment. The study is conducted at the effective
field theory level with the mono- signature incorporating varying levels of
systematic uncertainties at the high-luminosity LHC. The projected collider
reach on the anapole moment is then compared to the reach coming from direct
detection experiments like LZ. Finally, the analysis is applied to a weakly
coupled completion with leptophilic dark matter.Comment: 24 pages, 9 figure
Charged Higgs Boson Pairs at the LHC
We compute the cross section for pair production of charged Higgs bosons at
the LHC and compare the three production mechanisms. The bottom-parton
scattering process is computed to NLO, and the validity of the bottom-parton
approach is established in detail. The light-flavor Drell-Yan cross section is
evaluated at NLO as well. The gluon fusion process through a one-loop amplitude
is then compared with these two results. We show how a complete sample of
events could look, in terms of total cross sections and distributions of the
heavy final states.Comment: 15 pages with 8 figure
Uniform flow of viscoelastic fluids past a confined falling cylinder
Uniform steady flow of viscoelastic fluids past a cylinder placed between two moving parallel plates is investigated numerically with a finite-volume method. This configuration is equivalent to the steady settling of a cylinder in a viscoelastic fluid, and here, a 50% blockage ratio is considered. Five constitutive models are employed
(UCM, Oldroyd-B, FENE-CR, PTT and Giesekus) to assess the effect of rheological properties on the flow kinematics and wake patterns. Simulations were carried out under
creeping flow conditions, using very fine meshes, especially in the wake of the cylinder where large normal stresses
are observed at high Deborah numbers. Some of the results are compared with numerical data from the literature,
mainly in terms of a drag coefficient, and significant discrepancies are found, especially for the constant-viscosity
constitutive models. Accurate solutions could be obtained up to maximum Deborah numbers clearly in excess of those reported in the literature, especially with the PTT and FENECR
models. The existence or not of a negative wake is identified for each set of model parameters
Vacuolar cells seem to be a special trait of the esophagus and crop of carnivorous cephalaspideans (Euopisthobranchia)
Monitoring the production of AAV vectors in insect cells by fluorescence spectroscopy
Adeno-associated viruses (AAV) are among the most promising viral vectors for gene therapy, since they can transduce non-dividing cells from several tissues while maintaining a long-term gene expression. Besides, AAVs possess low immunogenicity compared to other viral vectors, and are physically resistant, which makes them resilient to industrial manufacturing conditions, long-term storage, and in vivo administration. One of the systems available for large scale production of AAVs is the insect cell-baculovirus expression vector system (IC-BEVS). Insect cells grow in suspension to high cell densities with modest growth requirements and without the need of serum supplementation. Consequently, scaling up the production in order to achieve the large number of AAV needed for clinical trials is more straight‑forward than with transfection-based systems.
However, methods for online monitoring of AAV production are still lacking. Such methods would allow determination of the best time of harvest in real-time, thus allowing recovery of AAV as soon as its concentration medium was higher.
Here we apply Fluorescence Spectroscopy to baculovirus-infected insect cell cultures producing adeno‑associated virus vectors, correlating the spectra to critical process parameters like cell concentration, viability and AAV concentration. Sf9 cells were co-infected with two baculovirus (expressing AAV rep and cap and a CMV-GFP transgene) at low or high multiplicities of infection (MOI), and the culture was followed by Fluorescence Spectroscopy in situ through a bioreactor probe.
After an exploratory calibration using data from only one bioreactor, we attested the aptitude of this technique to capture overall data trend: using a 3 component PLS model, we have obtained a calibration NRMSE of 2.9% for total AAV particles per cell, 5.9% for viable cell density and 0.9% for viability). Additional bioreactor productions using different infection parameters (CCI, MOI, time of infection) allowed testing the robustness of fluorescence monitoring to process variability. With this dataset, we tested several pre-treatment methods for the raw spectra, as well as different regression algorithms in order to establish a good predictive model. Ultimately, fluorescence spectroscopy provides a simple tool for online monitoring of key process variables in baculovirus-infected insect cell cultures.
Acknowledgments: Funding from Fundação para a Ciência e a Tecnologia, projects EXPL/BBBBIO/1129/2013 and Daniel Pais’ PhD research grant PD/BD/105873/2014
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