Technology requirements for future Earth-to-geosynchronous orbit transportation systems. Volume 1: Executive summary

Technologies including accelerated technology that are critical to performance and/or provide cost advantages for future space transportation systems are identified. Mission models are scoped and include priority missions, and cargo missions. Summary data, providing primary design concepts and features, are given for the SSTO, HLLV, POTV, and LCOTV vehicles. Significant system costs and total system costs in terms of life cycle costs in both discounted and undiscounted dollars are summarized for each of the vehicles

Technology requirements for future Earth-to-geosynchronous orbit transportation systems. Volume 3: Appendices

Technological requirements and forecasts of rocket engine parameters and launch vehicles for future Earth to geosynchronous orbit transportation systems are presented. The parametric performance, weight, and envelope data for the LOX/CH4, fuel cooled, staged combustion cycle and the hydrogen cooled, expander bleed cycle engine concepts are discussed. The costing methodology and ground rules used to develop the engine study are summarized. The weight estimating methodology for winged launched vehicles is described and summary data, used to evaluate and compare weight data for dedicated and integrated O2/H2 subsystems for the SSTO, HLLV and POTV are presented. Detail weights, comparisons, and weight scaling equations are provided

“Supply and demand trends for fertilizer in Zimbabwe: 1930 to date”: Key drivers and lessons learnt

The fertilizer sector in Zimbabwe has evolved over the years in response to different policy changes based on the government’s priorities on agricultural development. The industry grew from the 1930s that targeted primarily large scale commercial farmers, through the liberalization period of the mid 1990s, and recent changes that have introduced controls on the marketing system. Since 2000, following the fast track land reform program, Zimbabwe has faced food insecurity challenges that have been exacerbated by the political and economic crises. This prompted the government to adopt policies that have reduced private sector interests in fertilizer supply. In this situation where explicit fertilizer markets have been absent, relief programs have been leading in facilitating deliveries of fertilizers to poorer smallholder farmers located even in remote areas. The supply of fertilizers in Zimbabwe has been driven by government policy, finance and infrastructure while the demand has primarily been a function of farmer’s capacity to acquire fertilizers, availability of water and farmers knowledge of fertilizer use. There is need for a policy shift that promotes a competitive fertilizer marketing to support a broader range of farmers in Zimbabwe leading to agricultural productivity growth. Investment in infrastructure is critical to reduce marketing costs and to boost fertilizer demand; policies that strengthen farmer’s capacity to acquire fertilizers and increase their knowledge on fertilizer use complemented by technologies that promote water use efficiencies are needed.Fertilizer, supply and demand, policy reform, consumption trends, Crop Production/Industries,

The Zipf law for random texts with unequal probabilities of occurrence of letters and the Pascal pyramid

We model the generation of words with independent unequal probabilities of occurrence of letters. We prove that the probability $p(r)$ of occurrence of words of rank $r$ has a power asymptotics. As distinct from the paper published earlier by B. Conrad and M. Mitzenmacher, we give a brief proof by elementary methods and obtain an explicit formula for the exponent of the power law.Comment: 4 page

The advertisement call and clutch size of the Golden-capped Boulder-frog Cophixalus pakayakulangun (Anura: Microhylidae)

[Extract] In Australia, the family Microhylidae consists of 19 species of Cophixalus Boettger 1892 and 5 species of Austrochaperina Fry 1912 (Hoskin 2012; Hoskin, submitted). Most of these species have highly localized distributions in the rainforests and boulder-fields of north-east Australia (Zweifel 1985; Hoskin 2004; Hoskin & Aland 2011). Australian microhylid frogs are terrestrial breeders with direct development (Zweifel 1985; Hoskin 2004; Anstis et al. 2011). The natural history of Australia’s microhylids is fairly well known, with the basics of breeding biology such as calls and clutch sizes published for most species (Zweifel 1985; Hoskin 2004; Anstis et al. 2011; Hoskin & Aland 2011; Hoskin 2012; Hoskin, submitted). Hoskin & Aland (2011) described two new species from Cape York Peninsula, C. pakayakulangun and C. kulakula, each restricted to boulder-field areas only 30 km apart but readily distinguished by morphology and genetics. Calls could not be compared because the call of C. pakayakulangun was not known at that time. Clutch information for C. pakayakulangun was also not available at the time of description

Influence of relative NK-DC abundance on placentation and its relation to epigenetic programming in the offspring

Normal placentation relies on an efficient maternal adaptation to pregnancy. Within the decidua, natural killer (NK) cells and dendritic cells (DC) have a critical role in modulating angiogenesis and decidualization associated with pregnancy. However, the contribution of these immune cells to the placentation process and subsequently fetal development remains largely elusive. Using two different mouse models, we here show that optimal placentation and fetal development is sensitive to disturbances in NK cell relative abundance at the fetal–maternal interface. Depletion of NK cells during early gestation compromises the placentation process by causing alteration in placental function and structure. Embryos derived from NK-depleted dams suffer from intrauterine growth restriction (IUGR), a phenomenon that continued to be evident in the offspring on post-natal day 4. Further, we demonstrate that IUGR was accompanied by an overall reduction of global DNA methylation levels and epigenetic changes in the methylation of specific hepatic gene promoters. Thus, temporary changes within the NK cell pool during early gestation influence placental development and function, subsequently affecting hepatic gene methylation and fetal metabolism.Fil: Freitag, Nancy. Medicine University of Berlin; AlemaniaFil: Zwier, M. V.. University of Groningen; Países BajosFil: Barrientos, Gabriela Laura. Medicine University of Berlin; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tirado González, Irene. Medicine University of Berlin; AlemaniaFil: Conrad, Melanie L.. Medicine University of Berlin; AlemaniaFil: Rose, Matthias. Medicine University of Berlin; AlemaniaFil: Scherjon, S. A.. University of Groningen; Países BajosFil: Plösch, T.. University of Groningen; Países BajosFil: Blois, Sandra M.. Medicine University of Berlin; Alemani

Robotic Intracorporeal Ileal Conduit Formation: Initial Experience from a Single UK Centre

Objectives. To describe our technique of robotic intracorporeal ileal conduit formation (RICIC) during robotic-assisted radical cystectomy (RARC). To report our initial results of this new procedure. Patients and Methods. Seven male and one female patients underwent RARC with RICIC over a six-month period. Demographic, operative, and outcome data was collected prospectively. Median patient age was 75 years (range 62–78 years). Median followup was 9 months (range 7–14 months). Results. RARC with RICIC was performed successfully in all eight patients. The median total operating time was 360 minutes (range 310–440 minutes) with a median blood loss of 225 mL (range 50–1000 mL). The median length of stay was nine days (range 6–34 days). Four patients (50%) were discharged within seven days. Four patients (50%) experienced one or more complications. This included two Clavien I complications, two Clavien II complications, and two Clavien III complications. Two patients (25%) required transfusion of two units each. To date, there have been no complications associated with the ileal conduit. Conclusion. Whilst being technically challenging, this procedure is safe, feasible, and reproducible. Patients who avoid complication show potential for rapid recovery and early discharge

Advances in Measurement and Force Modeling for Improved GNSS-based Precise Orbit Determination of CYGNSS and Sentinel-6 MF

Precise orbit determination (POD) based on global navigation satellite systems (GNSS) tracking is fundamental to many space-based geodesy missions. The research presented here develops and implements improvements to the models and methods for two missions: CYGNSS, a lowcost constellation of small satellites, and Sentinel-6 Michael Freilich (MF), the current reference global ocean altimeter mission. The orbit solutions are improved though the advancement of the measurement models, dynamic force models, and solution strategies. CYGNSS is a constellation of eight small satellites designed to use reflected GNSS signals for retrieval of ocean surface winds. The navigation requirements to achieve this primary mission are quite loose, allowing the project to use simple point positioning, with a single-frequency GPS receiver, to support mission orbit needs. Research presented here demonstrates that orbits with 3-D positioning accuracy better than 10 cm can be achieved, with an iterative solution strategy that includes calibration of the antenna, use of combined code and carrier GRAPHIC (GRoup And PHase Ionosphere Correction) observables, and correction of a timing difference between code and carrier measurements. The process is validated using comparable data from the GRACE (Gravity Recovery and Climate Experiment) mission, for which high precision reference orbits are available. To support stringent POD requirements, Sentinel-6 MF is equipped with multiple tracking instruments: a TriG GPS receiver, a pair of redundant PODRIX GNSS (GPS + Galileo) receivers, a satellite laser retroreflector, and a Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) receiver. The first study develops an improved dynamic solar radiation pressure model. Compared to the previously used macromodel, this results in more consistent estimates of drag and solar scale parameters throughout changes in the orientation of the sun relative to the orbit plane (beta angle). The second study improves the measurement model by extending the new GPS IIIA transmitter antenna calibration out to boresight angles of 14-17 degrees, which are not observed by ground-based receivers, but are quite important for receivers in low Earth orbit. Implementation of this extension produces solutions that incorporate GPS IIIA measurements with statistics consistent with older satellite families. Finally, applying lessons learned from the previous studies, orbit solutions are generated from all available Sentinel-6 MF GNSS tracking data. This multi-receiver/GNSS configuration with two independent receivers and constellations (GPS + Galileo) revealed a range bias effect in the TriG GNSS observations that can be calibrated. Processing the calibrated TriG and PODRIX observations separately results in highly accurate orbit solutions, which are both consistent with one-way satellite laser ranging (SLR) residuals at the level of 6.9 mm rms. When processed together, the TriG plus PODRIX multi-GNSS solutions produced the most accurate orbit solutions with one-way SLR residual rms of 6.8 mm</p