289 research outputs found
User's guide to the Mission Analysis Evaluation and Space Trajectory Operations program (MAESTRO)
The MAESTRO system is a mission analysis tool designed to present to the user information necessary to make the various decisions required in the design and execution of a spaceflight mission. The system was designed so that it can be used in both the pre-launch mission planning phase of a mission and during the flight as an in-flight decision making tool. A description of each of the following modes is presented: (1) trajectory propagation mode; (2) retro-fire determination mode; (3) midcourse analysis determination mode; (4) Monte Carlo mode; (5) verification mode; (6) orbit stability mode; and (7) post injection trim mode. A description of the inputs necessary to run the program mode is given along with a sample case
SPARC Controls Melanoma Cell Plasticity through Rac1.
Cell transition to a more aggressive mesenchymal-like phenotype is a hallmark of cancer progression that involves different steps and requires tightly regulated cell plasticity. SPARC (Secreted Protein Acidic and Rich in Cysteine) is a matricellular protein that promotes this transition in various malignant cell types, including melanoma cells. We found that suppression of SPARC expression in human melanoma cells compromised cell migration, adhesion, cytoskeleton structure, and cell size. These changes involved the Akt/mTOR pathway. Re-expression of SPARC or protein addition restored all the cell features. Suppression of SPARC expression was associated with increased Rac1-GTP levels and its membrane localization. Expression of the dominant negative mutant of Rac1 counteracted almost all the changes observed in SPARC-deficient cells. Overall, these data suggest that most of the SPARC-mediated effects occurred mainly through the blockade of Rac1 activity.Fil: Salvatierra Colussi, Edgardo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Alvarez, Mariano J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Leishman, Claudia C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Rivas Baquero, Elvia Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Lutzky, Viviana P.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina. The Royal Brisbane Hospital; AustraliaFil: Chuluyan, Hector Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; ArgentinaFil: Podhajcer, Osvaldo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin
On the Lie symmetries of a class of generalized Ermakov systems
The symmetry analysis of Ermakov systems is extended to the generalized case
where the frequency depends on the dynamical variables besides time. In this
extended framework, a whole class of nonlinearly coupled oscillators are viewed
as Hamiltonian Ermakov system and exactly solved in closed form
Two dimensional dynamical systems which admit Lie and Noether symmetries
We prove two theorems which relate the Lie point symmetries and the Noether
symmetries of a dynamical system moving in a Riemannian space with the special
projective group and the homothetic group of the space respectively. The
theorems are applied to classify the two dimensional Newtonian dynamical
systems, which admit a Lie point/Noether symmetry. Two cases are considered,
the non-conservative and the conservative forces. The use of the results is
demonstrated for the Kepler - Ermakov system, which in general is
non-conservative and for potentials similar to the H\`enon Heiles potential.
Finally it is shown that in a FRW background with no matter present, the only
scalar cosmological model which is integrable is the one for which 3-space is
flat and the potential function of the scalar field is exponential. It is
important to note that in all applications the generators of the symmetry
vectors are found by reading the appropriate entry in the relevant tables.Comment: 25 pages, 17 table
Involutive orbits of non-Noether symmetry groups
We consider set of functions on Poisson manifold related by continues
one-parameter group of transformations. Class of vector fields that produce
involutive families of functions is investigated and relationship between these
vector fields and non-Noether symmetries of Hamiltonian dynamical systems is
outlined. Theory is illustrated with sample models: modified Boussinesq system
and Broer-Kaup system.Comment: LaTeX 2e, 10 pages, no figure
El fenómeno blog. Los blogs y su importancia en la comunicación institucional
Un blog es un sitio web fácil de usar en el cual puede, entre otras muchas cosas, expresar rápidamente sus opiniones e interactuar con otros usuarios. Todo ello gratis. Los weblogs, sitios web compuestos por entradas individuales dispuestas en la página en orden cronológico inverso, estructurados originalmente como diarios personales, basados en enlaces, noticias y opiniones que se actualizan de modo regular, escritos con un estilo informal y subjetivo, han sido muchas cosas a lo largo de estos 10 años, han ido cambiando con la propia Red del mismo modo que ha ido cambiado su percepción social y su impacto cultural, económico, político y mediático
Secreted protein acidic and rich in cysteine produced by human melanoma cells modulates polymorphonuclear leukocyte recruitment and antitumor cytotoxic capacity
The expression of secreted protein acidic and rich in cysteine (SPARC) has been associated with the malignant progression of different types of human cancer. SPARC was associated with tumor cell capacity to migrate and invade, although its precise role in tumor progression is still elusive. In the present study, we show that SPARC produced by melanoma cells modulates the antitumor activity of polymorphonuclear leukocytes (PMN). Administration to nude mice of human melanoma cells in which SPARC expression was transiently or stably knocked down by antisense RNA (SPARC-sup cells) promoted PMN recruitment and obliterated tumor growth even when SPARC-sup cells accounted for only 10% of injected malignant cells. In addition, SPARC-sup cells stimulated the in vitro migration and triggered the antimelanoma cytotoxic capacity of human PMN, an effect that was reverted in the presence of SPARC purified from melanoma cells or by reexpressing SPARC in SPARC-sup cells. Leukotrienes, interleukin 8, and growth-related oncogene, in combination with Fas ligand and interleukin 1, mediated SPARC effects. These data indicate that SPARC plays an essential role in tumor evasion from immune surveillance through the inhibition of the antitumor PMN activity.Facultad de Ciencias Veterinaria
Secreted protein acidic and rich in cysteine produced by human melanoma cells modulates polymorphonuclear leukocyte recruitment and antitumor cytotoxic capacity
The expression of secreted protein acidic and rich in cysteine (SPARC) has been associated with the malignant progression of different types of human cancer. SPARC was associated with tumor cell capacity to migrate and invade, although its precise role in tumor progression is still elusive. In the present study, we show that SPARC produced by melanoma cells modulates the antitumor activity of polymorphonuclear leukocytes (PMN). Administration to nude mice of human melanoma cells in which SPARC expression was transiently or stably knocked down by antisense RNA (SPARC-sup cells) promoted PMN recruitment and obliterated tumor growth even when SPARC-sup cells accounted for only 10% of injected malignant cells. In addition, SPARC-sup cells stimulated the in vitro migration and triggered the antimelanoma cytotoxic capacity of human PMN, an effect that was reverted in the presence of SPARC purified from melanoma cells or by reexpressing SPARC in SPARC-sup cells. Leukotrienes, interleukin 8, and growth-related oncogene, in combination with Fas ligand and interleukin 1, mediated SPARC effects. These data indicate that SPARC plays an essential role in tumor evasion from immune surveillance through the inhibition of the antitumor PMN activity.Facultad de Ciencias Veterinaria
Anomalies in T cell function are associated with individuals at risk of mycobacterium abscessus complex infection
The increasing global incidence and prevalence of non-tuberculous mycobacteria (NTM) infection is of growing concern. New evidence of person-to-person transmission of multidrug-resistant NTM adds to the global concern. The reason why certain individuals are at risk of NTM infections is unknown. Using high definition flow cytometry, we studied the immune profiles of two groups that are at risk of Mycobacterium abscessus complex infection and matched controls. The first group was cystic fibrosis (CF) patients and the second group was elderly individuals. CF individuals with active M. abscessus complex infection or a history of M. abscessus complex infection exhibited a unique surface T cell phenotype with a marked global deficiency in TNFa production during mitogen stimulation. Importantly, immune-based signatures were identified that appeared to predict at baseline the subset of CF individuals who were at risk of M. abscessus complex infection. In contrast, elderly individuals with M. abscessus complex infection exhibited a separate T cell phenotype underlined by the presence of exhaustion markers and dysregulation in type 1 cytokine release during mitogen stimulation. Collectively, these data suggest an association between T cell signatures and individuals at risk of M. abscessus complex infection, however, validation of these immune anomalies as robust biomarkers will require analysis on larger patient cohorts
Heuristics for Broader Assessment of Effectiveness and Usability in Technology-Mediated Technical Communication
Purpose: To offer additional tools for the assessment of effectiveness and usability in technology-mediated communication based in established heuristics.
Method: An interdisciplinary group of researchers at Rensselaer Polytechnic Institute selected five disparate examples of technology-mediated communication, formally evaluated each using contemporary heuristics, and then engaged in an iterative design process to arrive at an expanded toolkit for in depth analyses.
Results: A set of heuristics and operationalized metrics for the deeper analysis of a broader scope of contemporary technology-mediated communication.
Conclusions: The continual evolution of communication, including the emergence of new, interactive media, provides a challenging opportunity to identify effective approaches and techniques. There are benefits to a renewed focus on relationships between people and between people and information, and we offer additional criteria and metrics to supplement established means of heuristic analysis
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