Architecting space communication networks under mission demand uncertainty

NASAs Space Network has been a successful program that has provided reliable communication and navigation services for three decades. As the third generation of satellites is being launched, alternatives to the current architecture of the system are being studied in order to improve the performance of the system, reduce its costs and facilitate its integration with the Near Earth Network and the Deep Space Network. Within this context, past research has proven the feasibility of efficiently exploring a large space of alternative network architectures using a tradespace search framework. Architecting a space communication network is a complex task that requires consideration of uncertainty, namely (1) factoring in customer demand variability, (2) predicting technology improvements and (3) considering possible budgetary constraints. This paper focuses on adding uncertainty associated with (1) to the existing communications network architecture tool by describing a heuristic-based model to derive mission concept of operations (conops) as a function of communication requirements. The accuracy of the model is assessed by comparing real conops from current TDRSS-supported missions with the predicted concept of operations. The model is used to analyze how customer forecast uncertainty affects the choice of the future network architecture. In particular, four customer scenarios are generated and compared with the current TDRSS capabilities.United States. National Aeronautics and Space Administration (NNX11AR70G

Síndrome de insensibilidad completa a los andrógenos: reporte de un caso, ilustración del manejo quirúrgico

ResumenEl término “desorden en la diferenciación sexual” (DDS) representa un grupo de anormalidades en el desarrollo del tracto genitourinario, en el cual ocurre un desarrollo atípico en uno o más niveles: cromosómico, gonadal o anatómico. Los genéticamente varones 46XY pueden presentarse con genitales externos fenotípicamente femeninos o ambiguos. El síndrome de insensibilidad a los andrógenos se podría considerar una enfermedad causada por la resistencia a la acción androgénica, causada por la mutación Xq11-12, que afecta los receptores androgénicos; la presentación clínica dependerá del grado de insensibilidad, leve (masculino infértil), moderada o completa como en nuestro caso. Requiere seguimiento por psicólogo y psiquíatra para familiares y paciente, para un desarrollo psicosexual adecuado, antes y después del tratamiento quirúrgico definitivo.El objetivo del presente artículo es realizar una revisión sistemática de los artículos publicados en la base de datos de Medline, para identificar la epidemiología e incidencia del síndrome de insensibilidad completa a los andrógenos, así como reconocer su abordaje, tratamiento y seguimiento de estos casos.Se presenta paciente de 23 años de edad, sin antecedentes patológicos de importancia, la cual inicia su estudio a los 17 años de edad por el Servicio de Ginecología, por presentar amenorrea y falta de desarrollo en caracteres sexuales secundarios, tiene estudios de imagen sin evidenciar estructuras Müllerianas; se realiza laparoscopía diagnóstica en 2 ocasiones sin poder identificar órganos sexuales femeninos o vestigios de testículos; estudio hormonal con niveles de estrógenos y testosterona evidentemente bajos con hormona folículo estimulante (FSH), hormona luteinizante (LH) y hormona liberadora de gonadotropinas dentro de parámetros normales; el cariotipo reporta 46XY. En ese momento se ofrece apoyo psiquiátrico, se decide continuar con educación femenina, por lo que se resuelve colocación de prótesis mamaria. Finalmente, se nos interconsulta para la realización de vaginoplastía con uso de segmento intestinal como canal vaginal.AbstractThe term “disorders of sexual differentiation” (DSD) encompasses a group of abnormalities in the development of the genitourinary tract. Atypical development occurs at one or more chromosomal, gonadal, or anatomic levels. 46 XY genetic males may present with external genitals that are phenotypically female or ambiguous. Androgen insensitivity syndrome could be considered a disease caused by resistance to androgenic action due to the Xq11-12 mutation that affects the androgenic receptors. Clinical presentation depends on the degree of insensitivity: mild (infertile male), partial, or complete, as with our patient. Psychologic and psychiatric follow-up is required for both the patient and family members so there can be adequate psychosexual development before and after definitive surgical treatment.The aim of this article was to conduct a systematic review of published reports in the MEDLINE database to identify the epidemiology and incidence of complete androgen insensitivity syndrome and to examine the approach, treatment, and follow-up of these cases.We present herein a 23-year-old patient, with an unremarkable pathologic history, who began to be studied by the Gynecology Service at 17 years of age due to amenorrhea and lack of secondary sexual development. Imaging studies failed to show Müllerian structures. Diagnostic laparoscopy was performed on 2 occasions in which female sexual organs or vestiges of testes were unable to be identified. Hormonal study revealed obviously low levels of estrogens and testosterone, and follicle-stimulating hormone (FSH), luteinizing hormone (LH), and gonadotropinreleasing hormone were within normal parameters; 46XY karyotype was reported. Psychiatric support was then offered. It was decided that the patient would continue to be raised and treated as a female and therefore she was given breast implants. Our service was subsequently consulted for performing vaginoplasty using an intestinal segment as the vaginal canal

Performance characterization of a multiplexed space-to-ground optical network

Advances in phased array systems for multi-beam free space optical communications are a key enabler for a new space-to-ground network architecture, namely a multiplexed optical architecture. The fundamental idea of a multiplexed space-to-ground optical network is the utilization of a multi-beam optical payload that allows each spacecraft to establish links with multiple ground stations within its line of sight. Information is then downlinked in parallel, from the satellite to the ground, through the subset of links not disrupted by clouds. In this paper we evaluate the performance of a multiplexed optical space-to-ground architecture from a systems perspective, with particular emphasis on the effect of cloud correlation in the network throughput. In particular, we first derive the expected data volume returned in a multiplexed architecture as a function of the optical network availability and the system total capacity. Then, we compare the performance of the proposed multiplexed architecture against a traditional single-beam downlink system that utilizes site diversity to mitigate cloud coverage effects. This comparison is based on two canonical scenarios, a global highly uncorrelated network representative of a geosynchronous satellite; and local, highly correlated, network representative of a low Earth orbit spacecraft. Through this analysis, we demonstrate that multiplexed architectures can improve the throughput of a space-to-ground optical network as compared to that of a single ground telescope without requiring a beam switching mechanism

Evidence for a change in the nuclear mass surface with the discovery of the most neutron-rich nuclei with 17<Z <25

The results of measurements of the production of neutron-rich nuclei by the fragmentation of a 76-Ge beam are presented. The cross sections were measured for a large range of nuclei including fifteen new isotopes that are the most neutron-rich nuclides of the elements chlorine to manganese (50-Cl, 53-Ar, 55,56-K, 57,58-Ca, 59,60,61-Sc, 62,63-Ti, 65,66-V, 68-Cr, 70-Mn). The enhanced cross sections of several new nuclei relative to a simple thermal evaporation framework, previously shown to describe similar production cross sections, indicates that nuclei in the region around 62-Ti might be more stable than predicted by current mass models and could be an indication of a new island of inversion similar to that centered on 31-Na.Comment: 4 pages, 3 figures, to be published in Physical Review Letters, 200

Beta-decay of nuclei around Se-90. Search for signatures of a N=56 sub-shell closure relevant the r-process

Nuclear structure plays a significant role on the rapid neutron capture process (r-process) since shapes evolve with the emergence of shells and sub-shells. There was some indication in neighboring nuclei that we might find examples of a new N=56 sub-shell, which may give rise to a doubly magic Se-90 nucleus. Beta-decay half lives of nuclei around Se-90 have been measured to determine if this nucleus has in fact a doubly-magic character. The fragmentation of Xe-136 beam at the National Superconducting Cyclotron Laboratory at Michigan State University was used to create a cocktail of nuclei in the A=90 region. We have measured the half lives of twenty-two nuclei near the r-process path in the A=90 region. The half lives of As-88 and Se-90 have been measured for the first time. The values were compared with theoretical predictions in the search for nuclear-deformation signatures of a N=56 sub-shell, and its possible role in the emergence of a potential doubly-magic Se-90. The impact of such hypothesis on the synthesis of heavy nuclei, particularly in the production of Sr, Y and Zr elements was investigated with a weak r-process network. The new half lives agree with results obtained from a standard global QRPA model used in r-process calculations, indicating that Se-90 has a quadrupole shape incompatible with a closed N=56 sub-shell in this region. The impact of the measured Se-90 half-life in comparison with a former theoretical predication associated with a spherical half-life on the weak-r-process is shown to be strong

Production cross sections of neutron rich isotopes from a 82Se beam

Production cross sections for neutron-rich nuclei from the fragmentation of a 82Se beam at 139 MeV/u were measured. The longitudinal momentum distributions of 122 neutron-rich isotopes of elements $11 \le Z \le 32$ were determined by varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei including several isotopes first observed in this work. These are the most neutron-rich nuclides of the elements $22 \le Z \le 25$ (64Ti, 67V, 69Cr, 72Mn). One event was registered consistent with 70Cr, and another one with 75Fe. A one-body Qg systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. The current results confirm those of our previous experiment with a 76Ge beam: enhanced production cross sections for neutron-rich fragments near Z=20.Comment: Talk given at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

Present and Future Experiments with Stored Exotic Nuclei at Relativistic Energies

Recent progress is presented from experiments on masses and lifetimes of bare and few-electron exotic nuclei at GSI.Comment: Proceedings of International Conference on "Frontiers in Nuclear Structure, Astrophysics and Reactions", Kos, Greece, September 12-17, 200