20,894 research outputs found
The place of architectural design studios in Portugal in response to the Bologna agreement
The curriculum harmonization of European university courses, converging for a European High-er Education Area by the so called Bologna Process (1999-2010), relocated the debate about the specificity of education in architecture, and its traditional methodology of learning by design, within the University environment. This paper approaches the structural, organizational and curricular developments of a group of Portuguese architectural schools, describing the changes driven by the Bologna Process and inquiring to what extent they present a change to the organization, the contents and the significance of traditional teaching of architectural design.info:eu-repo/semantics/acceptedVersio
Kinetic conversion of CO to CH4 in the Solar System
Some of the most interesting chemistry in the Solar System involves changes in the oxidation state of the simple carbon species. The chemical pathways for the conversion of CH4 to CO and CO2 are for the most part known. The reverse process, the reduction of CO to CH4, is, however, poorly understood. This is surprising in view of the importance of the reduction process in the chemistry of the Solar System. Recently we investigated the chemical kinetics of a hitherto unsuspected reaction. It is argued that the formation of the methoxy radical (CH3O) from H+H2CO may play an essential role in the reduction of CO to CH4. The rate coefficient for this reaction has been estimated using the approximate theory of J. Troe and transition state theory. We will discuss the implications of this reaction for the chemistry of CO on Jupiter, in the solar nebula, for interpreting the laboratory experiments of A. Bar-Nun and A. Shaviv and A. Bar-Nun and S. Chang, and for organic synthesis in the prebiotic terrestrial atmosphere. The possible relation of CO reduction in the solar nebula and polyoxymethylene observed in comet Halley will be discussed
Bank strategic asset allocation under a unified risk measure
Most available bank asset allocation models use several risk measures as constraints; as a consequence, the comparison of the risk between different asset allocation strategies is often difficult, since each strategy is subject to several risks. With this research, we create a simulation–optimization methodology that measures interest rate, credit and liquidity risks in a unified manner. The associated risk events, such as interest rate increases, liquidity outflows or spikes in defaults are generated using the same simulation engine, giving as output a single risk measure (the probability of failure, used by ratings agencies) that aggregates those risks under the same simulation engine. Finally, we use our methodology to determine Pareto fronts for the optimal balance sheet allocations and minimum-risk strategies. As a result, several findings emerge, such as: 1) Risk is dependent on the income stream; 2) Allocation to book value assets is preferable; 3) Under low rate environments, a full allocation to cash is very risky and is not the minimum risk strategy; 4) Banks can make investments in stocks in environments of high prospective returns and low leverage.info:eu-repo/semantics/acceptedVersio
A 'p-n' diode with hole and electron-doped lanthanum manganite
The hole-doped manganite La0.7Ca0.3MnO3 and the electron-doped manganite
La0.7Ce0.3MnO3 undergo an insulator to metal transition at around 250 K, above
which both behave as a polaronic semiconductor. We have successfully fabricated
an epitaxial trilayer (La0.7Ca0.3MnO3/SrTiO3/La0.7Ce0.3MnO3), where SrTiO3 is
an insulator. At room temperature, i.e. in the semiconducting regime, it
exhibits asymmetric current-voltage (I-V) characteristics akin to a p-n diode.
The observed asymmetry in the I-V characteristics disappears at low
temperatures where both the manganite layers are metallic. To the best of our
knowledge, this is the first report of such a p-n diode, using the polaronic
semiconducting regime of doped manganites.Comment: PostScript text and 2 figures, to be published in Appl. Phys. Lett
Functional MRI with active, fully implanted, deep brain stimulation systems: Safety and experimental confounds
We investigated safety issues and potential experimental confounds when performing functional magnetic resonance imaging (fMRI) investigations in human subjects with fully implanted, active, deep brain stimulation (DBS) systems. Measurements of temperature and induced voltage were performed in an in vitro arrangement simulating bilateral DBS during magnetic resonance imaging (MRI) using head transmit coils in both 1.5 and 3.0 T MRI systems. For MRI sequences typical of an fMRI study with coil-averaged specific absorption rates (SARs) less than 0.4 W/kg, no MRI-induced temperature change greater than the measurement sensitivity (0.1 °C) was detected at 1.5 T, and at 3 T temperature elevations were less than 0.5 °C, i.e. within safe limits. For the purposes of demonstration, MRI pulse sequences with SARs of 1.45 W/kg and 2.34 W/kg (at 1.5 T and 3 T, respectively) were prescribed and elicited temperature increases (> 1 °C) greater than those considered safe for human subjects. Temperature increases were independent of the presence or absence of active stimulator pulsing. At both field strengths during echo planar MRI, the perturbations of DBS equipment performance were sufficiently slight, and temperature increases sufficiently low to suggest that thermal or electromagnetically mediated experimental confounds to fMRI with DBS are unlikely. We conclude that fMRI studies performed in subjects with subcutaneously implanted DBS units can be both safe and free from DBS-specific experimental confounds. Furthermore, fMRI in subjects with fully implanted rather than externalised DBS stimulator units may offer a significant safety advantage. Further studies are required to determine the safety of MRI with DBS for other MRI systems, transmit coil configurations and DBS arrangements
TD-DFT Monitoring of the Absorption Spectra of Polycyclic Aromatic Hydrocarbons over the Basque Country, Spain
Brown carbon is a type of carbonaceous aerosol with strong light absorption in the ultraviolet and visible wavelengths that leads to radiative forcing. However, it is difficult to correlate the chemical composition of brown carbon with its atmospheric light absorption properties, which translates into significant uncertainty. Thus, a time-dependent density functional theory (TD-DFT) approach was used to model the real-world absorption properties of 14 polycyclic aromatic hydrocarbons (PAHs) over three regions of the Basque Country (Spain): Bilbao, Urretxu, and Azpeitia. The data were corrected for atmospheric concentration. The results show that the absorption spectra over each region are qualitatively identical, with the absorption intensities being significantly higher over Bilbao than over Azpeitia and Urretxu. Furthermore, it was found that the light absorption by PAHs should be more relevant for radiative forcing when it occurs at UVA and (sub)visible wavelengths. Finally, among the 14 studied PAHs, benzo[b]fluoranthene, pyrene, fluoranthene, benzo[a]pyrene, and benzo[k]fluoranthene and benzoperylene were identified as the molecules with larger contributions to radiative forcing.</jats:p
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