Effect of tetraethoxysilane (TEOS) on melting gel behavior

To increase the connectivity of the molecular structure but not to prevent softening, small amounts of tetraethoxysilane (TEOS) were added to phenyl-substituted melting gels. The limit of the additions was determined when the melting gel lost its ability to soften. A comparison was made between TEOS diluted with ethanol, TEOS diluted with methanol, and tetramethoxysilane (TMOS) diluted with methanol. The additions had slight effects on the glass transition behavior, the gelling time and the indentation hardness. The role of the TEOS was both a form of dilution and a cross-linking promoter.     

Biomass fuel smoke exposure was associated with adverse cardiac remodeling and left ventricular dysfunction in Peru

While household air pollution from biomass fuel combustion has been linked to cardiovascular disease, the effects on cardiac structure and function have not been well described. We sought to determine the association between biomass fuel smoke exposure and cardiac structure and function by transthoracic echocardiography. We identified a random sample of urban and rural residents living in the high‐altitude region of Puno, Peru. Daily biomass fuel use was self‐reported. Participants underwent transthoracic echocardiography. Multivariable linear regression was used to examine the relationship of biomass fuel use with echocardiographic measures of cardiac structure and function, adjusting for age, sex, height, body mass index, diabetes, physical activity, and tobacco use. One hundred and eighty‐seven participants (80 biomass fuel users and 107 non‐users) were included in this analysis (mean age 59 years, 58% women). After adjustment, daily exposure to biomass fuel smoke was associated with increased left ventricular internal diastolic diameter (P=.004), left atrial diameter (P=.03), left atrial area (four‐chamber) (P=.004) and (two‐chamber) (P=.03), septal E′ (P=.006), and lateral E′ (P=.04). Exposure to biomass fuel smoke was also associated with worse global longitudinal strain in the two‐chamber view (P=.01). Daily biomass fuel use was associated with increased left ventricular size and decreased left ventricular systolic function by global longitudinal strain.     

Dielectric determination of bio‐ and free‐calcium in commercial alkaline‐cooked ground corn

Using dielectric measurements, it was possible to determine the concentration of bio‐ and free‐calcium in a corn dough prepared mixing commercial powder of alkaline‐cooked ground‐corn kernel (maize), Zea mays, with different concentrations of Ca(OH)₂ and the same amount of water. This allows determining the conditions to obtain dough with high bio‐calcium content and consequently high nutritional value. The samples were placed in the interior of a small parallel‐plate capacitor. The capacitance and the cell current profiles were obtained with the corresponding relaxation times as a function of the Ca concentration. With this information, it was possible to determine the threshold concentration at which the Ca ions are not longer linked chemically to the cornstarch molecules and move freely in the interior of the dough. A model based on the ionic conductivity was developed to explain the dependence of the relaxation times with the Ca concentration.     

Diacetyl reduction by commercial Saccharomyces cerevisiae strains during vinification

Microbially derived diacetyl accumulation during vinification imparts a buttery wine aroma, which has stylistic implications. However, at higher concentrations diacetyl induces an aromatic off‐flavour. Saccharomyces cerevisiae is able to reduce diacetyl to below the sensory threshold. Therefore, characterization of the diacetyl reduction in commercial wine yeasts creates new opportunities to manage the risk of wine associated off‐flavours. Diacetyl reduction by two commercial S. cerevisiae strains was characterized in Pinot blanc grape must of the vintage 2012 with different initial diacetyl concentrations (0–50 mg/L). Highest diacetyl reduction was found in the first two days after wine yeasts were inoculated. No further decrease in diacetyl content was observed after the fourth day. All assays in which diacetyl was added showed the same final diacetyl concentration of approximately 2 mg/L. However, a significantly lower amount of diacetyl was found in grape must without adding diacetyl. The present results indicate that commercial wine yeasts are able to reduce much higher amounts of diacetyl than normally expected during the vinification procedure. However, the constant final diacetyl concentration indicates that diacetyl accumulation may be the result of wine matrix binding effects, which prevent a complete reduction by active wine yeasts. Copyright © 2013 The Institute of Brewing & Distilling.     

Monetary Policy Under Time-Varying Uncertainty Aversion

In this paper we develop a framework to analyze the optimal policy of an inflation-targeting monetary authority that is not fully confident about its model and the degree of mistrust changes over time as the structure of the economy changes. These changes can include structural breaks as well as price, output or real exchange shocks. We use robust control to denote the degree of uncertainty aversion of the policy maker and a Markov chain to capture the time-varying nature of the uncertainty aversion. We find that in general a more aggressive interest rate policy is the optimal response to: (i) more uncertainty aversion and (ii) higher likelihood that the uncertainty aversion may appear in the future. Moreover, we find that the policy maker’s welfare decreases when there is an increase in uncertainty aversion. However, the transition probabilities in the Markov-chain have ambiguous effects on the policy maker expected losses.     

MMSEC-RAKE receivers with resolution reduction of the diversitybranches: analysis, simulation, and applications

In channels where the delay spread is smaller than the chip interval (e.g., an IS-95 system operating in indoor environments), spread-spectrum signals do not give rise to path diversity. In this situation, maximal-ratio combiner (MRC) RAKE receivers with resolution reduction (RR) of the diversity receiver branches may be used by the mobile stations to provide diversity gain, significantly improving system performance. A new resolution reduction technique based on the use of a minimum mean-square-error diversity combiner (MMSEC) is proposed in this work. We show that, under very general assumptions, this new method of RR is optimal. A detailed study of the performance of a dual-branch MMSEC-RAKE receiver with RR in a typical indoor office environment is presented. In order to allow a simple practical implementation, a suboptimal structure of the MMSEC is also proposed. Numerical results show that this new receiver scheme provides a 1.2-dB improvement over the previously proposed RR technique based on MRC, and a 4.9-dB improvement over conventional MRC-RAKE receiver without RR, at a frame-error rate of 0.01 for the downlink of the IS-95 system in a typical indoor office environment     

Surface Domain Structures and Mesoscopic Phase Transition in Relaxor Ferroelectrics

Relaxor ferroelectrics are a prototypical example of ferroic systems in which interplay between atomic disorder and order parameters gives rise to emergence of unusual properties, including non‐exponential relaxations, memory effects, polarization rotations, and broad spectrum of bias‐ and temperature‐induced phase transitions. Despite more than 40 years of extensive research following the original discovery of ferroelectric relaxors by the Smolensky group, the most basic aspect of these materials – the existence and nature of order parameter – has not been understood thoroughly. Using extensive imaging and spectroscopic studies by variable‐temperature and time resolved piezoresponse force microscopy, we find that the observed mesoscopic behavior is consistent with the presence of two effective order parameters describing dynamic and static parts of polarization, respectively. The static component gives rise to rich spatially ordered systems on the ～100 nm length scales, and are only weakly responsive to electric field. The surface of relaxors undergoes a mesoscopic symmetry breaking leading to the freezing of polarization fluctuations and shift of corresponding transition temperature.     

Stable time step estimates for mesh‐free particle methods

Real‐time computational biomechanics for medicine usually uses explicit time integration, because of its efficiency and suitability for parallel implementation. Explicit time integration is only conditionally stable and therefore requires an estimation of the maximum stable time step that can be used. In this paper we develop a method of estimating the stable time step for mesh‐free particle methods for a specific case of mass lumping: the mass associated with an integration point is distributed equally to all nodes found in the support domain of that integration point. Two estimates of the stable time step for each integration point are developed: one that is very accurate but more costly to compute and one less accurate but easier to implement. The results are also valid for the FEM and beyond computational biomechanics for medicine. Copyright © 2012 John Wiley & Sons, Ltd.