Thermal Subsystem Operational Times Analysis for Ubiquitous Small Satellites Relay in LEO

The success of the satellite subsystems engineering depends on the optimal design, modeling, simulation, and validation of the deliverables of the conceptual and mission design objectives. This paper presents the operational times analysis of the thermal control subsystem onboard a 97-kg microsatellite in low-Earth orbit during an eclipse period. Power-storing, communication downlink and uplink, payload processing, and thermal control overpower modes were implemented for a communication mission under worst-case orbital patterns. An embedded digital temperature and lighting controller circuitry was designed and practically validated to effect a desired logic. For an average eclipse period of 34.4 mins, the operational times of the thermal subsystem at altitudes of 400 km, 500 km, and 600 km are 38.6 mins, 38.1 mins, and 37.7 mins respectively. Moreover, the thermal control subsystem simulation reveals that reducing the operational times of non-thermal control subsystems during the eclipse period by 50 % can result in an operational factor of safety of over 1.5. At least 10 dB data link transmission margin can be achieved. The reported findings show that the operational times of spacecraft subsystems overpower modes can be reconfigured in orbit to reliably sustain the operating conditions of the capability-based satellite components for ubiquitous communication

Parametric System Engineering Analysis of Capability-based Small Satellite Missions

To achieve appropriate link budget and system engineering analyses of capability-based small satellites (CSSs) missions, an objective assessment and computation of the component-, subsystem-, and system-levels parameters requirements must be carried out. This paper presents the parametric models for the system engineering analysis of communication, meteorology, planetary, and other small satellite programmes with recourse to the initial mission, conceptual design, and post-mission objectives. Mass and power margins are the critical resources under investigation for achieving an economical and sustainable capability-based small satellite mission. Case study systems engineering analyses for meteorology, communication and planetary missions indicate a transmit power for communication uplink and downlink of at least 33 dBm. The parametric model also reveals a signal-to-noise ratio of at least 16 dB per radio communication link for worst-case noise floor and path loss. This holds a great promise for the development of adaptive subsystems for reconfigurable multiband, and multistandard transceivers for multipurpose missions and post-mission applications

Area spectral efficiency of a macro-femto heterogeneous network for cell-edge users under shadowing and fading effects

The traditional macro-only network is not effective, especially when communication signal is required for users far away from the macrocell base station and located in the cell edge. The signal strength reaching these users is excessively attenuated due to fading and shadowing. The deployment of femtocells around the cell edge of this macrocell helps to reduce the effect of fading and shadowing thereby increasing the overall efficiency of the cellular network. This holds a great promise for adaptive space-based wireless sensor networks, formation-flying satellites and constellations

Increased peri-ductal collagen micro-organization may contribute to raised mammographic density

BACKGROUND: High mammographic density is a therapeutically modifiable risk factor for breast cancer. Although mammographic density is correlated with the relative abundance of collagen-rich fibroglandular tissue, the causative mechanisms, associated structural remodelling and mechanical consequences remain poorly defined. In this study we have developed a new collaborative bedside-to-bench workflow to determine the relationship between mammographic density, collagen abundance and alignment, tissue stiffness and the expression of extracellular matrix organising proteins. METHODS: Mammographic density was assessed in 22 post-menopausal women (aged 54–66 y). A radiologist and a pathologist identified and excised regions of elevated non-cancerous X-ray density prior to laboratory characterization. Collagen abundance was determined by both Masson’s trichrome and Picrosirius red staining (which enhances collagen birefringence when viewed under polarised light). The structural specificity of these collagen visualisation methods was determined by comparing the relative birefringence and ultrastructure (visualised by atomic force microscopy) of unaligned collagen I fibrils in reconstituted gels with the highly aligned collagen fibrils in rat tail tendon. Localised collagen fibril organisation and stiffness was also evaluated in tissue sections by atomic force microscopy/spectroscopy and the abundance of key extracellular proteins was assessed using mass spectrometry. RESULTS: Mammographic density was positively correlated with the abundance of aligned periductal fibrils rather than with the abundance of amorphous collagen. Compared with matched tissue resected from the breasts of low mammographic density patients, the highly birefringent tissue in mammographically dense breasts was both significantly stiffer and characterised by large (>80 μm long) fibrillar collagen bundles. Subsequent proteomic analyses not only confirmed the absence of collagen fibrosis in high mammographic density tissue, but additionally identified the up-regulation of periostin and collagen XVI (regulators of collagen fibril structure and architecture) as potential mediators of localised mechanical stiffness. CONCLUSIONS: These preliminary data suggest that remodelling, and hence stiffening, of the existing stromal collagen microarchitecture promotes high mammographic density within the breast. In turn, this aberrant mechanical environment may trigger neoplasia-associated mechanotransduction pathways within the epithelial cell population. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13058-015-0664-2) contains supplementary material, which is available to authorized users

Effect Of Different Levels Of Raw Tropical Legumes On Selected Serum Biochemical Parameters Of Cockerels

Blood samples from matured cockerels fed various levels of different tropical legumes were analysed for some biochemical properties. These legumes include Jack Beans (JB), Benniseed (BN) and Bambara nut (BM) which were used as supplement to soya bean meal at 25% and 50% each in a six weeks feeding trial. Total protein of cockerels in all treatments did not differ significantly (P>0.05) being 3.843g/dl (control), 3.802g/dl (25% JB),3.627g/dl (50% JB), 3.770g/dl (25% BM), 3.595g/dl (50% BM), 3.990g/dl (25% BN) and 3.858g/dl (50% BN). Serum albumen ranged between 1.518g/dl and 1.678g/dl while serum globulins ranged between 2.170g/dl and2.340g/dl. There was no significant difference (P>0.05) between the seven groups of cockerels in respect to these parameters. Supplementation of soya beans with jack beans, benniseed and bambara nut at 25% and 50% was notdeleterious to matured cockerels considering these parameters

Hepatic Involvement In Systemic Amyloidosis – A Case Report

A 52 year old woman presented at the gastroenterology clinic of University of Nigeria Teaching Hospital Enugu with a 3-month history of pruritus, right upper abdominal pain, easy satiety and weight loss. She had been treated in a peripheral hospital 2 years earlier for epigastic pain. The main findings on physical examination were emaciation, scanty axillary hair, palmer erythema and hepatomegaly. Urine examination showed marked proteinuria. Serum alkaline phosphatase was markedly elevated. Histological examination of biopsy specimen of the liver showed marked hyaline-like amorphous perivascular and extravascular deposition, which proved to be amyloid with Congo red stain. The patient later developed persistent vomiting and had one episode of haematemesis. Barium meal showed severe deformity and scarring of the duodenal bulb. Gastrojenostomy was carried out but the patient died 3 hours after surgery from severe haematemesis. We conclude that the patients had amyloid infiltration of the liver with probable involvement of the kidneys and upper gastrointestinal tract Amyloidosis should be suspected in any patient with unexplained hepatopathy and proteinuria KEY WORDS: Amyloidosis, hepatic, cholestasis. Nigerian Journal of Clinical Practice Vol.7(2) 2004: 102-10