2,859 research outputs found
Magnetic Misalignment of Interstellar Dust Filaments
We present evidence for scale-independent misalignment of interstellar dust
filaments and magnetic fields. We estimate the misalignment by comparing
millimeter-wave dust-polarization measurements from Planck with filamentary
structures identified in neutral-hydrogen (HI) measurements from HI4PI. We find
that the misalignment angle displays a scale independence (harmonic coherence)
for features larger than the HI4PI beam width (). We additionally find a
spatial coherence on angular scales of . We present
several misalignment estimators formed from the auto- and cross-spectra of
dust-polarization and HI-based maps, and we also introduce a map-space
estimator. Applied to large regions of the high-Galactic-latitude sky, we find
a global misalignment angle of , which is robust to a variety of
masking choices. By dividing the sky into small regions, we show that the
misalignment angle correlates with the parity-violating cross-spectrum
measured in the Planck dust maps. The misalignment paradigm also predicts a
dust signal, which is of relevance in the search for cosmic birefringence
but as yet undetected; the measurements of are noisier than of , and
our correlations of with misalignment angle are found to be weaker and
less robust to masking choices. We also introduce an HI-based dust-polarization
template constructed from the Hessian matrix of the HI intensity, which is
found to correlate more strongly than previous templates with Planck dust
modes.Comment: 30 pages, 17 figure
Proton Wires in an Electric Field: the Impact of Grotthuss Mechanism on Charge Translocation
We present the results of the modeling of proton translocation in finite
H-bonded chains in the framework of two-stage proton transport model. We
explore the influence of reorientation motion of protons, as well as the effect
of electric field and proton correlations on system dynamics. An increase of
the reorientation energy results in the transition of proton charge from the
surrounding to the inner water molecules in the chain. Proton migration along
the chain in an external electric field has a step-like character, proceeding
with the occurrence of electric field threshold-type effects and drastic
redistribution of proton charge. Electric field applied to correlated chains
induces first a formation of ordered dipole structures for lower field
strength, and than, with a further field strength increase, a stabilization of
states with Bjerrum D-defects. We analyze the main factors responsible for the
formation/annihilation of Bjerrum defects showing the strong influence of the
complex interplay between reorientation energy, electric field and temperature
in the dynamics of proton wire.Comment: 28 pages, 9 figure
Activated carbons developed in different activation conditions to improve nitrate adsorption performance
The suitability of activated carbons (ACs)with dissimilar textural and surface chemistry characteristics was studied for nitrate removal, under different pH conditions. For this task, four ACs were used; two of them were manufactured bychemical and physical steam activation from orange peel and almond shell, while the other two were commercial adsorbents. It was found that both the precursor and activation methodology influence the adsorbents characteristics. Regarding nitrate uptake, their chemical surface was very relevant, while the textural properties did not exert a remarkable effect. Also, nitrate adsorption under acid pH was improved, especially for basic adsorbents, in contrast with neutral conditions, in which case no adsorbent stood out. The amelioration of nitrate removal for basic adsorbents and acidic pH conditions was associated to a greater prominence of electrostatic contributionsas well as a lower extent of adsorption competition between hydroxyl and nitrate ions.La idoneidad de carbones activados (CAs) con características texturales y de química superfical diferentes se estudió para la eliminación de nitratos bajo diferentes condiciones de pH. Para ello se utilizaron cuatro CAs; dos de ellos comerciales y otros dos manufacturados mediante activación química y física a partir de cáscara de naranja y de almendra, respectivamente. Los resultados obtenidos mostraron que el precursor y la metodología de activación influyen en las características adsorbentes. En cuanto a la capacidad de adsorción, su superficie química fue muy relevante, mientras que las propiedades texturales no ejercieron un efecto notable. Además, la adsorción de nitrato mejoró a pH ácido, especialmente en el caso de los adsorbentes básicos, lo cual se asoció a una mayor importancia de las contribuciones electrostáticas así como, una menor adsorción competitiva entre los iones hidroxilo y nitrato.Fil: Roman, S.. Universidad de Extremadura; EspañaFil: Ledesma, B.. Universidad de Extremadura; EspañaFil: Fernandez, Maria Emilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina. Universidad de Buenos Aires. Programa de Investigación y Desarrollo de Fuentes Alternativas de Materias Primas y Energia. Departamento de Industrias; ArgentinaFil: Nunell, Gisel Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina. Universidad de Buenos Aires. Programa de Investigación y Desarrollo de Fuentes Alternativas de Materias Primas y Energia. Departamento de Industrias; ArgentinaFil: Bonelli, Pablo Ricardo. Universidad de Buenos Aires. Programa de Investigación y Desarrollo de Fuentes Alternativas de Materias Primas y Energia. Departamento de Industrias; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cukierman, Ana Lea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Programa de Investigación y Desarrollo de Fuentes Alternativas de Materias Primas y Energia. Departamento de Industrias; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentin
A fractionally cointegrated VAR analysis of economic voting and political support
We use a fractionally cointegrated vector autoregressive model to examine the relationship between Canadian political support and macroeconomic conditions. This model is well suited for the analysis because it allows multiple fractional time series and admits simple asymptotic inference for the model parameters and tests of the hypotheses of interest. In the long-run equilibrium, we find that support for the Progressive Conservative Party was higher during good economic times, i.e. periods of high interest rates and low unemployment, while support for the Liberal Party was higher during bad economic times, i.e. periods of low interest rates and high unemployment. We also test and reject the notion that party support is driven only by relative (to the United States) economic performance. Indeed, our findings suggest that US macroeconomic variables do not enter the long-run equilibrium of Canadian economic voting (political opinion poll support) at all
Peptide-based microcapsules obtained by self-assembly and microfluidics as controlled environments for cell culture
Funding for this study was provided by the Portuguese Foundation for Science and Technology (FCT, grant PTDC/EBB-BIO/ 114523/2009). D. S. Ferreira gratefully acknowledges FCT for the PhD scholarship (SFRH/BD/44977/2008)
Tissue Compatibility of Two Biodegradable Tubular Scaffolds Implanted Adjacent to Skin or Buccal Mucosa in Mice
Radiation therapy for cancer in the head and neck region leads to a marked loss of salivary gland parenchyma, resulting in a severe reduction of salivary secretions. Currently, there is no satisfactory treatment for these patients. To address this problem, we are using both tissue engineering and gene transfer principles to develop an orally implantable, artificial fluid-secreting device. In the present study, we examined the tissue compatibility of two biodegradable substrata potentially useful in fabricating such a device. We implanted in Balb/c mice tubular scaffolds of poly-L-lactic acid (PLLA), poly-glycolic acid coated with PLLA (PGA/PLLA), or nothing (sham-operated controls) either beneath the skin on the back, a site widely used in earlier toxicity and biocompatibility studies, or adjacent to the buccal mucosa, a site quite different functionally and immunologically. At 1, 3, 7, 14, and 28 days postimplantation, implant sites were examined histologically, and systemic responses were assessed by conventional clinical chemistry and hematology analyses. Inflammatory responses in the connective tissue were similar regardless of site or type of polymer implant used. However, inflammatory reactions were shorter and without epithelioid and giant cells in sham-operated controls. Also, biodegradation proceeded more slowly with the PLLA tubules than with the PGA/PLLA tubules. No significant changes in clinical chemistry and hematology were seen due to the implantation of tubular scaffolds. These results indicate that the tissue responses to PLLA and PGA/PLLA scaffolds are generally similar in areas subjacent to skin in the back and oral cavity. However, these studies also identified several potentially significant concerns that must be addressed prior to initiating any clinical applications of this device.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63126/1/107632702760240562.pd
When is a Central Bank Governor Fired? Evidence Based on a New Data Set
This paper uses a new data set on the term in office of central bank governors in 137 countries covering the period 1970-2004 to estimate a model for the chance that a central bank governor is replaced. We formulate a number of hypotheses based on the literature on the determinants of central bank independence that are tested using conditional logit models and the Extreme Bounds Analysis. We conclude that, apart from the share of the current term in office elapsed, high levels of political and regime instability, the occurrence of elections, and high inflation increase the probability of a turnover
Government debt expansion and stock returns
Using an international dataset, this paper documents a negative association between increases in the central government debt-to-GDP ratio and dollar-denominated stock index returns. Depending on the estimation method, raising the debt ratio by one percentage point diminishes the stock returns by between 39 to 95 basis points. We show that this result cannot be explained by changes in the investment risk. Instead, government debt issuance exerts upward pressure on private interest rates and appears to signal a greater tax burden in the future. These two factors coincide to produce a fall in stock market prices
Dielectric and thermal relaxation in the energy landscape
We derive an energy landscape interpretation of dielectric relaxation times
in undercooled liquids, comparing it to the traditional Debye and
Gemant-DiMarzio-Bishop pictures. The interaction between different local
structural rearrangements in the energy landscape explains qualitatively the
recently observed splitting of the flow process into an initial and a final
stage. The initial mechanical relaxation stage is attributed to hopping
processes, the final thermal or structural relaxation stage to the decay of the
local double-well potentials. The energy landscape concept provides an
explanation for the equality of thermal and dielectric relaxation times. The
equality itself is once more demonstrated on the basis of literature data for
salol.Comment: 7 pages, 3 figures, 41 references, Workshop Disordered Systems,
Molveno 2006, submitted to Philosophical Magazin
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