Application of electrical resistivity for the control of water content and density in loess

Argentinean loess is a typical collapsible soil which strength and stiffness are mainly governed by water content and unit weight. Electrical resistivity of soils depends fundamentally from water content, porosity, and salt concentration in the pore fluid. The interest of this work is to discuss the applicability of electrical resistivity survey to predict variations in density and water content in loess. Samples of loess were prepared in laboratory at varied densities and water contents. The results show that loess resistivity depends mainly on water content and that soil density has little influence. Mapping water content distribution by means of resistivity measurements is possible if salt concentration in pore fluid is known in advance and assumed uniformly distributed in the whole soil mass. A real scale work is described here for which resistivity mapping was used successfully to evaluate distribution of water content in loess formation.Fil: Rinaldi, V. Universidad Nacional de Córdoba; Argentina.Ingeniería de la Construcció

Bandgap Narrowing in Quantum Wires

In this paper we consider two different geometry of quasi one-dimensional semiconductors and calculate their exchange-correlation induced bandgap renormalization (BGR) as a function of the electron-hole plasma density and quantum wire width. Based on different fabrication scheme, we define suitable external confinement potential and then leading-order GW dynamical screening approximation is used in the calculation by treating electron-electron Coulomb interaction and electron-optical phonon interaction. Using a numerical scheme, screened Coulomb potential, probability of different states, profile of charge density and the values of the renormalized gap energy are calculated and the effects of variation of confinement potential width and temperature are studied.Comment: 17 Pages, 4 Figure

Pseudo-static pile load test: expirience on pre-bored and large diameter piles

Pseudostatic load test is usually employed as an alternative to the conventional static load test for piles. Recent developments showed that the well developed Statnamic tests can be substantially simplified by using a hanging weight falling over a cushion system that allows increasing the time length of the generated stress pulse. This work describes the design of the test method and a recently experience related to the application of the pseudostatic load test used to evaluate the bearing capacity of large diameter piles. The performed test showed that using moderate loads from 10 to 20 tons falling from 10 cm to 120 cm and cushions prepared at varied stiffness allowed to reach more than 800 tons of loading and the fully mobilization of the pile ultimate capacity. The main advantages of the proposed pseudostatic tests respect to the conventional Statnamic tests is the possibility to apply load increments by steps, the repeatability of each loading step and the simpler test setup required by the former.Fil: Rinaldi, V. A. Universidad Nacional de Córdoba; Argentina.Fil: Viguera, R. CIM SRL consultants; Argentina.Ingeniería de la Construcció

Parameterized thermal macromodeling for fast and effective design of electronic components and systems

We present a parameterized macromodeling approach to perform fast and effective dynamic thermal simulations of electronic components and systems where key design parameters vary. A decomposition of the frequency-domain data samples of the thermal impedance matrix is proposed to improve the accuracy of the model and reduce the number of the computationally costly thermal simulations needed to build the macromodel. The methodology is successfully applied to analyze the impact of layout variations on the dynamic thermal behavior of a state-of-the-art 8-finger AlGaN/GaN HEMT grown on a SiC substrate

Thinking beyond organism energy use: A trait-based bioenergetic mechanistic approach for predictions of life history traits in marine organisms

The functional trait-based bioenergetic approach is emergent in many ecological spectra, from the conservation of natural resources to mitigation and adaptation strategies in a global climate change context. Such an approach relies on being able to exploit mechanistic rules to connect environmental human-induced variability to functional traits (i.e. all those specific traits defining species in terms of their ecological roles) and use these to provide estimates of species life history traits (LH; e.g. body size, fecundity per life span, number of reproductive events). LHs are species-specific and proximate determinants of population characteristics in a certain habitat. They represent the most valuable quantitative information to investigate how broad potential distributional boundaries of a species are, and to feed predictive population models. There is much to be found in the current literature that describes mechanistic functional trait-based bioenergetics models, using them to test ecological hypotheses, but a mathematical framework often renders interpretation and use complicated. Here, we wanted to present a simpler interpretation and description of one of the most important recent mechanistic bioenergetic theories: the dynamic energy budget theory by Kooijman (Dynamic Energy Budget Theory for Metabolic Organisation, 2010, Cambridge University Press, Cambridge). Our main aim was to disentangle those aspects that at first reading may seem too mathematically challenging to many marine biologists, ecologists and environmental scientists, and present them for use in mechanistic applications

On Adiabatic Renormalization of Inflationary Perturbations

We discuss the impact of adiabatic renormalization on the power spectrum of scalar and tensor perturbations from inflation. We show that adiabatic regularization is ambiguous as it leads to very different results, for different adiabatic subtraction schemes, both in the range v\equiv k/(aH) \gsim 0.1 and in the infrared regime. All these schemes agree in the far ultraviolet, $v\gg 1$. Therefore, we argue that in the far infrared regime, $v\ll 1$, the adiabatic expansion is no longer valid, and the unrenormalized spectra are the physical, measurable quantities. These findings cast some doubt on the validity of the adiabatic subtraction at horizon exit, $v=1$, to determine the perturbation spectra from inflation which has recently advocated in the literature.Comment: 7 pages, 3 figures, revtex. New version with more results and modified plot

The Human SLC25A33 and SLC25A36 Genes of Solute Carrier Family 25 Encode Two Mitochondrial Pyrimidine Nucleotide Transporters

The human genome encodes 53 members of the solute carrier family 25 (SLC25), also called the mitochondrial carrier family, many of which have been shown to transport inorganic anions, amino acids, carboxylates, nucleotides, and coenzymes across the inner mitochondrial membrane, thereby connecting cytosolic and matrix functions. Here two members of this family, SLC25A33 and SLC25A36, have been thoroughly characterized biochemically. These proteins were overexpressed in bacteria and reconstituted in phospholipid vesicles. Their transport properties and kinetic parameters demonstrate that SLC25A33 transports uracil, thymine, and cytosine (deoxy)nucleoside di- and triphosphates by an antiport mechanism and SLC25A36 cytosine and uracil (deoxy)nucleoside mono-, di-, and triphosphates by uniport and antiport. Both carriers also transported guanine but not adenine (deoxy)nucleotides. Transport catalyzed by both carriers was saturable and inhibited by mercurial compounds and other inhibitors of mitochondrial carriers to various degrees. In confirmation of their identity (i) SLC25A33 and SLC25A36 were found to be targeted to mitochondria and (ii) the phenotypes of Saccharomyces cerevisiae cells lacking RIM2, the gene encoding the well characterized yeast mitochondrial pyrimidine nucleotide carrier, were overcome by expressing SLC25A33 or SLC25A36 in these cells. The main physiological role of SLC25A33 and SLC25A36 is to import/export pyrimidine nucleotides into and from mitochondria, i.e. to accomplish transport steps essential for mitochondrial DNA and RNA synthesis and breakdown

Static and dynamic response analysis of stay cables using terrestrial laser scanning and vibration measurements

Nowadays, high accuracy measurements provided by terrestrial laser scanner and vision sensors allow to collect useful and exhaustive information about the conditions of the existing structures, useful to detect defects and geometry anomalies and to better understand their mechanical behavior. These avant-garde technologies were found to be particularly effective for the structural health assessment of the cable-stayed pedestrian bridge described in this paper. Considering a continuous mono-dimensional model of an inclined perfectly flexible cable, the axial tension is locally tangent to the cable profile. Thus, determining the cable static response under self-weight consists of a geometric shape-finding problem. Through terrestrial laser scanning, a 3D point cloud model of the bridge was acquired, including a data-abundant description of the actual static configuration of the stays. Therefore, cable configuration was no longer an unknown of the static problem, which can be inverted to assess the static tension. Furthermore, modal analysis was conducted also through image-based vibrations measurements to identify the fundamental frequencies of the cables. The independent identification of the axial forces from static (geometric) and dynamic (spectral) data provided results in good agreement