An assessment of technology alternatives for telecommunications and information management for the space exploration initiative

On the 20th anniversary of the Apollo 11 lunar landing, President Bush set forth ambitious goals for expanding human presence in the solar system. The Space Exploration Initiative (SEI) addresses these goals beginning with Space Station Freedom, followed by a permanent return to the Moon, and a manned mission to Mars. A well designed, adaptive Telecommunications, Navigation, and Information Management (TNIM) infrastructure is vital to the success of these missions. Utilizing initial projections of user requirements, a team under the direction of NASA's Office of Space Operations developed overall architectures and point designs to implement the TNIM functions for the Lunar and Mars mission scenarios. Based on these designs, an assessment of technology alternatives for the telecommunications and information management functions was performed. This technology assessment identifies technology developments necessary to meet the telecommunications and information management system requirements for SEI. Technology requirements, technology needs and alternatives, the present level of technology readiness in each area, and a schedule for development are presented

Epidemic model with isolation in multilayer networks

The Susceptible-Infected-Recovered (SIR) model has successfully mimicked the propagation of such airborne diseases as influenza A (H1N1). Although the SIR model has recently been studied in a multilayer networks configuration, in almost all the research the isolation of infected individuals is disregarded. Hence we focus our study in an epidemic model in a two-layer network and we use an isolation parameter w to measure the effect of quarantining infected individuals from both layers during an isolation period tw. We call this process the Susceptible-Infected-Isolated-Recovered (SIIR) model. Using the framework of link percolation we find that isolation increases the critical epidemic threshold of the disease because the time in which infection can spread is reduced. In this scenario we find that this threshold increases with w and tw. When the isolation period is maximum there is a critical threshold for w above which the disease never becomes an epidemic. We simulate the process and find an excellent agreement with the theoretical results.We thank the NSF (grants CMMI 1125290 and CHE-1213217) and the Keck Foundation for financial support. LGAZ and LAB wish to thank to UNMdP and FONCyT (Pict 0429/2013) for financial support. (CMMI 1125290 - NSF; CHE-1213217 - NSF; Keck Foundation; UNMdP; Pict 0429/2013 - FONCyT)Published versio

Epidemic Model with Isolation in Multilayer Networks

The Susceptible-Infected-Recovered (SIR) model has successfully mimicked the propagation of such airborne diseases as influenza A (H1N1). Although the SIR model has recently been studied in a multilayer networks configuration, in almost all the research the isolation of infected individuals is disregarded. Hence we focus our study in an epidemic model in a two-layer network, and we use an isolation parameter to measure the effect of isolating infected individuals from both layers during an isolation period. We call this process the Susceptible-Infected-Isolated-Recovered ($SI_IR$) model. The isolation reduces the transmission of the disease because the time in which infection can spread is reduced. In this scenario we find that the epidemic threshold increases with the isolation period and the isolation parameter. When the isolation period is maximum there is a threshold for the isolation parameter above which the disease never becomes an epidemic. We also find that epidemic models, like $SIR$ overestimate the theoretical risk of infection. Finally, our model may provide a foundation for future research to study the temporal evolution of the disease calibrating our model with real data.Comment: 18 pages, 5 figures.Accepted in Scientific Report

Evaluation of components, subsystems, and networks for high rate, high frequency space communications

The development of new space communications technologies by NASA has included both commercial applications and space science requirements. NASA's Systems Integration, Test and Evaluation (SITE) Space Communication System Simulator is a hardware based laboratory simulator for evaluating space communications technologies at the component, subsystem, system, and network level, geared toward high frequency, high data rate systems. The SITE facility is well-suited for evaluation of the new technologies required for the Space Exploration Initiative (SEI) and advanced commercial systems. Described here are the technology developments and evaluation requirements for current and planned commercial and space science programs. Also examined are the capabilities of SITE, the past, present and planned future configurations of the SITE facility, and applications of SITE to evaluation of SEI technology

Interacting social processes on interconnected networks

We propose and study a model for the interplay between two different dynamical processes --one for opinion formation and the other for decision making-- on two interconnected networks $A$ and $B$. The opinion dynamics on network $A$ corresponds to that of the M-model, where the state of each agent can take one of four possible values ($S=-2,-1,1,2$), describing its level of agreement on a given issue. The likelihood to become an extremist ($S=\pm 2$) or a moderate ($S=\pm 1$) is controlled by a reinforcement parameter $r \ge 0$. The decision making dynamics on network $B$ is akin to that of the Abrams-Strogatz model, where agents can be either in favor ($S=+1$) or against ($S=-1$) the issue. The probability that an agent changes its state is proportional to the fraction of neighbors that hold the opposite state raised to a power $\beta$. Starting from a polarized case scenario in which all agents of network $A$ hold positive orientations while all agents of network $B$ have a negative orientation, we explore the conditions under which one of the dynamics prevails over the other, imposing its initial orientation. We find that, for a given value of $\beta$, the two-network system reaches a consensus in the positive state (initial state of network $A$) when the reinforcement overcomes a crossover value $r^*(\beta)$, while a negative consensus happens for $r<r^*(\beta)$. In the $r-\beta$ phase space, the system displays a transition at a critical threshold $\beta_c$, from a coexistence of both orientations for $\beta<\beta_c$ to a dominance of one orientation for $\beta>\beta_c$. We develop an analytical mean-field approach that gives an insight into these regimes and shows that both dynamics are equivalent along the crossover line $(r^*,\beta^*)$.Comment: 25 pages, 6 figure

Application of Transition Metal Phosphine Complexes in the Modeling of Catalytic Processes: Reactivity with Hydrosilanes and Other Industrially Relevant Substrates

The first two chapters of this thesis are devoted to exploring the reactivity of electron rich molybdenum and tungsten trimethylphosphine complexes with hydrosilanes. These complexes, Mo(PMe₃)₆ and W(PMe₃)₄(η²-CH₂PMe₂)H, have been shown to be highly reactive species that undergo a number of bond cleavage reactions. In the presence of the hydrosilanes PhxSiH₄-x (x = 0 - 4), Mo(PMe₃)₆ and W(PMe₃)₄(η²-CH₂PMe₂)H effect Si-H and Si-C bond cleavage, along with Si-Si bond formation; however, the products derived from these reactions are drastically different for Mo(PMe₃)₆ and W(PMe₃)₄(η²-CH₂PMe₂)H and are highly dependent on the substitution of the silane. Mo(PMe₃)₆ reacts with SiH₄, PhSiH₃, and Ph₂SiH₂ to afford novel silyl, hypervalent silyl, silane, and disilane complexes, as respectively illustrated by Mo(PMe₃)₄H2(SiH3)₂, Mo(PMe₃)₄H(k₂-H₂-H₂SiPh₂H), Mo(PMe₃)₃H₄(s-HSiHPh₂), and Mo(PMe₃)₃H₂(k₂-H₂-H₂Si₂Ph₄). Mo(PMe₃)₄H(k₂-H₂-H2Si2Ph₄) is the first example of a complex with a hypervalent [H₂SiPh₂HH] ligand, and Mo(PMe₃)₃H2(k₂-H₂-H₂Si₂Ph₄) represents the first structurally characterized disilane complex. In addition to being structurally unique, these complexes also possess interesting reactivity. For example, Mo(PMe₃)₄((SiH₃)₂H₂ undergoes isotope exchange with SiD₄, and NMR spectroscopic analysis of the SiHxD₄₋ₓ isotopologues released indicates that the reaction occurs via a sigma bond metathesis pathway. In contrast, W(PMe₃)₄(η²-CH₂PMe₂)H affords a range of products that includes metallacycle, disilyl, silane, and bridging silylene complexes. The disilyl compounds, W(PMe₃)₄H₃(SiH₂SiHPh₂) and W(PMe₃)₃H₄SiH₂Ph)(SiH₂SiHPh₂), exhibit the ability of W(PMe₃)₄(n₂-CH₂PMe₂)H to cause both redistribution and Si-Si bond formation. A mechanism involving silylene intermediates is proposed for the generation of these complexes, and this mechanism is supported computationally. Additional support for the presence of intermediates comes from the isolation of a unique complex with a bridging silylene ligand, "WSiW". The bridging silylene bonding motif is unprecedented. The reactivity of the simplest hydrosilane, SiH₄, was also examined with IrCl(CO)(PPh₃)₂ (i.e. Vaska's compound). Previous reports on this reaction have assigned the product as trans-IrH(SiH₃)(Cl)(CO)(PPh₃)₂, in which the hydride and silyl ligands are mutually trans. It is noteworthy, therefore, that we have now obtained a crystal structure of the product of this reaction in which the hydride and silyl ligands are cis, namely cis-IrH(SiH₃)(Cl)(CO)(PPh₃)₂. Calculated energies of the isomeric species also suggest that the product of this reaction was originally misassigned. These results, and the analogous reactions with germane (GeH₄), are described in Chapter 4. Chapter 4 also discusses some reactions of transition metal phosphine complexes, including Ru(PMe₃)₄H₂, Mo(PMe₃)₆, W(PMe₃)₄(η²-CH₂PMe₂)H, and Mo(PMe₃)₄(η²-CH₂PMe₂)H, with industrially relevant substrates. Ru(PMe₃)₄H₂ effects the water gas shift reaction of CO and H2O to form CO2 and H2. Furthermore, Ru(PMe₃)₄H₂ reacts with CO₂, CS₂, and H₂S to respectively form formate, thiocarbonate, and hydrosulfido complexes. The reactivity of Mo(PMe₃)₆ and W(PMe₃)₄(η²-CH₂PMe₂)H towards molecules relevant to the hydrodeoxygenation industry, including dihydrofuran and benzofuran, was studied. The products of these reactions exhibit hydrogenation of unsaturated bonds and C-O bond cleavage, both of which are essential to the hydrodeoxygenation process. Mo(PMe₃)₄(η²-CH₂PMe₂)H reacts with PhI to form an alkylidyne species, [Mo(PMe₃)₄(CPMe₂Ph)I]I, which was structurally characterized by X-ray diffraction. W(PMe₃)₄(η²-CH₂PMe₂)H forms a k2-adduct when treated with 2-seleno-2-methylbenzimidazole, namely W(PMe₃)₄(sebenzimᴹᵉ)H. Chapter 3 discusses the development of two new ruthenaboratrane complexes, [k⁴-B(mimᴮᵘᵗ)₃]Ru(CO)(PR₃) (R = Ph, Me). The structures of these complexes are described, and their d⁶ metal configuration is supported by both Fenske-Hall and Natural Bond Orbital calculations. Some reactivity of these complexes was also explored. For example, [k⁴-B(mimᴮᵘᵗ)₃]Ru(CO)(PMe₃) appears to add MeI across the Ru-B bond. Finally, as an extension of the work that we have done on tungsten trimethylphosphine complexes, the structure of W(PMe₃)₃H₆ in solution was investigated, and the results are presented in Chapter 5. T₁ measurements of the hydride ligands and deuterium isotope effect shifts both confirm that this complex exists as a classical hydride in solution, which is in accord with the classical hydride formulation in the solid state that was previously determined by X-ray diffraction

Numerical Arc Segmentation Algorithm for a Radio Conference (NASARC), version 4.0: User's manual

The information in the NASARC (Version 4.0) Technical Manual (NASA-TM-101453) and NASARC (Version 4.0) User's Manual (NASA-TM-101454) relates to the state of Numerical Arc Segmentation Algorithm for a Radio Conference (NASARC) software development through November 1, 1988. The Technical Manual describes the NASARC concept and the algorithms used to implement the concept. The User's Manual provides information on computer system considerations, installation instructions, description of input files, and program operation instructions. Significant revisions were incorporated in the Version 4.0 software over prior versions. These revisions have further enhanced the modeling capabilities of the NASARC procedure and provide improved arrangements of predetermined arcs within the geostationary orbit. Array dimensions within the software were structured to fit within the currently available 12-megabyte memory capacity of the International Frequency Registration Board (IFRB) computer facility. A piecewise approach to predetermined arc generation in NASARC (Version 4.) allows worldwide planning problem scenarios to be accommodated within computer run time and memory constraints with enhanced likelihood and ease of solution

Breve notícia sobre o "Kormtchaja Kniga"

Os código s d e lei s sã o uma da s principai s fonte s históricas . Alegislação, considerad a como produto da sua época , nos revela a s própriasestrutura s d a sociedad e d a qua l emano u e , po r outr o lado , con -siderada como norma , reflet e fielment e o esforç o conscient e po r mei odo qua l o homem tentou plasma r a sua civilização. Conhece r a lei, éconhecer a respectiv a époc a o u civilização . Apesa r d o luga r comum,a descobert a e a decifraçã o d o Códig o d e Hamurab i é a melho r de -monstração d a noss a afirmação

Identidad para sí de los inmigrantes taiwaneses jóvenes

El fenómeno migratorio siempre fue relevante en el quehacer de la sociedad argentina. A los contingentes de inmigrantes europeos y latinoamericanos se incorporaron en las últimas décadas los de origen asiático, entre ellos los taiwaneses. Al igual que para los demás inmigrantes, el proceso de adaptación a la sociedad argentina presenta desafíos en cuanto a su identidad. Mantenerse “taiwanés” o transformarse en “argentino” es una cuestión que de alguna manera cada uno de los inmigrantes taiwaneses debe resolver. Sin embargo, intuimos que existen elementos comunes que generan tensión entre la adopción de una y otra identidad. El presente trabajo pretende indagar en el aspecto identitario del proceso de adaptación de los inmigrantes taiwaneses jóvenes. En primer lugar se presentan los aspectos teóricos que guiaron la recolección y análisis de los datos. Siguen a continuación, una explicación de los aspectos metodológicos, el análisis de los datos y unas breves conclusiones.Facultad de Humanidades y Ciencias de la Educació