Postan - A Package for Postoptimal Analysis (An Extension of Minos)

This paper presents a new software package which has been developed in collaboration with IIASA The new package, POSTAN, is designed for postoptimal analysis of linear programming problems, and is embedded in the well-known linear and nonlinear programming code MINOS. POSTAN is composed of a number of FORTRAN subroutines which may be called by adding some new keywords to the original list of MINOS specifications. The main function of POSTAN is to determine the ranges in which certain parameters may be changed without affecting the optimal solution and/or the optimal basis. In this paper the authors outline the general form of the linear programming problems studied, describe the six new subroutines in some detail, and illustrate this description with a printout obtained in the solution of a sample problem. The mathematical theory behind the software package is given in an Appendix

Postan 3 - Extended Postoptimal Analysis Package for Minos

This paper is one of the series of 11 Working Papers presenting the software for interactive decision support and software tools for developing decision support systems. These products constitute the outcome of the contracted study agreement between the System and Decision Sciences Program at IIASA and several Polish scientific institutions. The theoretical part of these results is presented in the IIASA Working Paper WP-88-071 entitled "Theory, Software and Testing Examples in Decision Support Systems" which contains the theoretical and methodological backgrounds of the software systems developed within the project. This paper presents the POSTAN 3 package. This package constitutes the tool for postoptimal analysis for linear and linear-fractional programming problems. POSTAN consists of a number of FORTRAN routines which are incorporated into MINOS, the well known linear and nonlinear programming code developed at the Stanford University. The postoptimal analysis is performed after MINOS has found an optimal solution and is initiated by extending the original MINOS specification file. The main function of POSTAN is ranging with respect to parameters specified by the user and computing the sensitivity coefficients

Comparative Analysis of Medium Voltage AC and DC Network Infrastructure Models

An increasing amount of consumer devices and end-use applications of electricity at the low voltage level that require a direct current (DC) power source have continued to advance in modern day society. At the same time the existing alternating current (AC) infrastructure that has served so well over the past century is beginning to show its age and vulnerability, leading to increased outages and reduced reliability. Also, the amount of high voltage direct current (HVDC) transmission system installations continue to increase around the world because of their proven superiority to high voltage alternating current (HVAC) in certain scenarios. However, with the widespread development and maturation in recent years of low voltage DC devices and systems, as well as large scale HVDC systems, no DC-based infrastructure or delivery system exists to efficiently connect the two together. Such an infrastructure would be developed through a medium voltage DC (MVDC) architecture. In order to properly analyze the benefits of a MVDC infrastructure for power distribution networks, a comparison between MVDC and MVAC architectures is necessary to identify advantages and disadvantages of both approaches. Investigating an architecture that would supply DC power to loads that is not much different in function to the existing AC grid system used today may bring with it increased efficiencies, therefore leading to economic operational and reliability benefits. To the author's knowledge, this thesis provides the first system scale comparative analysis of this nature comparing MVAC and MVDC. The preliminary design for such a system to supply DC power was created in this thesis using the PSCAD software package. The system analyzed utilizes a medium voltage DC bus rated at 20kV with a set of interconnected loads and generation. The DC system, while complicated with its wide array of power electronic converters, grants the ability to control power flow into the system from the different generation sources and to the loads. While the infrastructure design created is an initial step for a larger system, it lays the foundation for the future development of a DC distribution system for real world applications

As "Vespas americanas" de Machado de Assis

Breve introdução à publicação, nesta Machadiana digital, das duas colunas “Vespas Americanas” publicadas em junho de 1864 na revista Semana Ilustrada e inéditas em livro, assinadas por Gil, pseudônimo utilizado na juventude por Machado de Assis

O mistério do oratório do alto do Morro da Providência, no Rio de Janeiro

The article seeks to unravel the mystery of the oratory at the top of Morro da Providência, in the waterfront of Rio de Janeiro, supposedly built to celebrate the arrival of the 20th century, but which already appears in photographs and engravings from previous times. To do this, it will go back to the invasion of Rio de Janeiro in 1711 and the subsequent attempt to fortify the city, looking for evidence that the aforementioned oratory was not built from scratch, but took advantage of an old observation tower that pre-existed in that location.El artículo busca desentrañar el misterio del oratorio en lo alto del Morro da Providência, en la Zona Portuaria de Río de Janeiro, supuestamente construido para celebrar la llegada del siglo XX, pero que ya aparece en fotografías y grabados de épocas anteriores. Para ello, se remontará a la invasión de Río de Janeiro en 1711 y al posterior intento de fortificar la ciudad, buscando evidencia de que el mencionado oratorio no fué construído desde cero, sino que aprovechó una antigua torre de observación que preexistía en esse lugar.O artigo procura desvendar o mistério do oratório do alto do Morro da Providência, na Zona Portuária do Rio de Janeiro, supostamente erguido para comemorar a chegada do século XX, mas que já aparece em fotografias e gravuras de épocas anteriores. Para isso, retrocederá à invasão do Rio de Janeiro de 1711 e à subsequente tentativa de fortificar a cidade, buscando evidências de que o referido oratório não foi construído do zero, mas utilizou-se de uma antiga atalaia de observação preexistente naquele local

Influence of Lipid Oxidization on Structures and Functions of Biological Membranes

The primary aim of this thesis is to clarify how the structures and functions of biological membranes are influenced by the oxidative damage mediated by free radicals. As a precisely defined model systems, artificially reconstituted lipid membranes (Langmuir monolayers, vesicles, supported membranes, multilamellar membranes) incorporating two oxidized phospholipids bearing aldehyde or carboxyl groups at the end of truncated sn-2 acyl chains were fabricated. By the combination of various experimental methods, the generic impact of chain oxidization on physical characteristics of membranes (e.g. lateral cooperativity, fine-structures perpendicular to membrane planes, electrostatics) and the specific interactions of oxidized phospholipids with EO6 peptides and acute immune response proteins was investigated. In the first step, the influence of oxidized phospholipids (OxPL) on the thermodynamics and electrostatics were investigated using Langmuir film balance at the air-water interface. The pressure-area (π-A) isotherms and surface potential (Δψ-A) measurements implied that both OxPLs lead to a decrease in the isothermal compression modulus. In fact, surface potential measurements suggest changes in the orientation of oxidized moieties that decrease the lateral cooperativity. Further increase in the fraction of oxidized lipids resulted in the loss of molecules into bulk water, which seems consistent with the destabilization of cell membranes under oxidative stresses. In the second step, the impact of lipid oxidization on the electrostatics of membranes was examined by the combination of high-energy specular X-ray reflectivity (XRR) and grazing-incidence X-ray fluorescence (GIXF). The scattering length density profiles reconstructed from XRR results suggested that both OxPL leads to membrane thinning, which seems plausible from the decrease in the lateral cooperativity suggested by Langmuir isotherms. GIXF offers an unique possibility to localize specific target elements within Å accuracy, suggesting that the binding affinity (Ca2+ > Cs+ > K+) could be interpreted in terms of the solvation entropy (Hofmeister series). Further, the impact of oxidization on the vertical structural ordering of vertically stacked membrane models was investigated by off-specular neutron scattering. A decreased lamellar periodicity d indicated that incorporation of OxPL into the membrane displace water molecules from the inter-membrane region due to the reorientation of oxidized moieties. In the third step, the combination of experimental techniques was utilized to shed light on specific interactions of OxPLs with peptides and proteins; C-reactive protein that is characteristic for the acute immune responses and monoclonal antibody EO6 to oxidized lipids. Following the fundamental characterization of membrane-protein interactions using isothermal titration calorimetry (ITC) and dynamic light scattering (DLS) of vesicle suspensions, in addition to XRR, GIXF, off-specular neutron scattering, dual waveguide polarization interferometry (DPI) was used to monitor the changes in thickness, refractive index, and the optical anisotropy (birefringence) of lipid membranes simultaneously. Furthermore, the specific binding of EO6 was verified from the fluorescence imaging of glioblastoma multiforme cells undergoing apoptosis, where a clear accumulation of OxPLs could be identified in apoptotic blebs. The obtained results demonstrated that the combination of well defined membrane models and unique physical techniques is a powerful tool to shed a new quantitative light on the generic and specific impacts of lipid oxidization on the lateral cooperativity, vertical fine-structures, electrostatics, and specific interactions in inflammation and apoptosis