The Detection of Iridium Using Laser-Induced Breakdown Spectroscopy

Although one thinks of a thruster as utilizing both a fuel and an oxidizer, as well as an ignition source to release molecular energy, thrusters exist that combine the fuel and oxidizer in a single fluid. These monopropellant thrusters can utilize either an ignition source or a catalyst to release the molecular energy stored within the propellant. Monopropellant thrusters are especially attractive for space flight systems because they only require a single propellant line which reduces systems weight and complexity. Some monopropellant thrusters, including legacy hydrazine thrusters, and newer thrusters using hydrazine replacements, that utilize a heterogeneous catalyst have experienced performance anomalies due to the degradation of the catalyst bed. At the Air Force Research Laboratory, current state-of-health diagnostic techniques ate being developed to better understand this catalyst bed degradation for the new hydrazine replacement monopropellant, AF-M315E. Laser-induced Breakdown Spectroscopy (LIBS) is being used to detect and quantify active catalyst materials in the exhaust plume, such as iridium. Previous work has been unsuccessful in detecting iridium. However, by shortening the delay settings on the camera detector, the spectrometer used in LIBS will be able to pick up more of the emissions from the laser-ablated sample, leading to the detection of iridium. DISTRIBUTION A: Approved for public release: distribution unlimited

Assessment of disk MHD generators for a base load powerplant

Results from a study of the disk MHD generator are presented. Both open and closed cycle disk systems were investigated. Costing of the open cycle disk components (nozzle, channel, diffuser, radiant boiler, magnet and power management) was done. However, no detailed costing was done for the closed cycle systems. Preliminary plant design for the open cycle systems was also completed. Based on the system study results, an economic assessment of the open cycle systems is presented. Costs of the open cycle disk conponents are less than comparable linear generator components. Also, costs of electricity for the open cycle disk systems are competitive with comparable linear systems. Advantages of the disk design simplicity are considered. Improvements in the channel availability or a reduction in the channel lifetime requirement are possible as a result of the disk design

Colorectal carcinogenesis: an archetype of gut microbiota-host interaction

Sporadic colorectal cancer (CRC) remains a major cause of worldwide mortality. Epidemiological evidence of markedly increased risk in populations that migrate to Western countries, or adopt their lifestyle, suggests that CRC is a disease whose aetiology is defined primarily by interactions between the host and his environment. The gut microbiome sits directly at this interface and is now increasingly recognised as a modulator of colorectal carcinogenesis. Bacteria such as Fusobacterium nucleatum and Escherichia coli (E. Coli) are found in abundance in patients with CRC and have been shown in experimental studies to promote neoplasia. A whole armamentarium of bacteria-derived oncogenic mechanisms has been defined, including the subversion of apoptosis and the production of genotoxins and pro-inflammatory factors. But the microbiota may also be protective: for example, they are implicated in the metabolism of dietary fibre to produce butyrate, a short chain fatty acid, which is anti-inflammatory and anti-carcinogenic. Indeed, although our understanding of this immensely complex, highly individualised and multi-faceted relationship is expanding rapidly, many questions remain: Can we define friends and foes, and drivers and passengers? What are the critical functions of the microbiota in the context of colorectal neoplasia

Stroke in Devon: knowledge was good, but action was poor.

BACKGROUND AND AIM: Effective implementation of early treatment strategies for stroke requires prompt admission to hospital. There are several reasons for delayed admission. Good awareness should facilitate early admission. We identified local targets for education. METHODS: Four groups, each of 40 people, completed questionnaires to determine their knowledge of stroke symptoms and risk factors, and the action they took or would take in the event of a stroke. The groups were: patients with a diagnosis of stroke or TIA (within 48 hrs of admission); patients at risk of stroke; the general population; and nurses. RESULTS: Forty per cent of stroke patients identified their stroke. Median time from onset of symptoms to seeking medical help was 30 minutes. Medical help was sought by the patient themselves in only 15% of cases. In 80% of cases the GP was called rather than an ambulance. Of the at risk group, 93% were able to list at least one symptom of acute stroke, as were 88% of the general population. An ambulance would be called by 73% of the at risk group in the event of a stroke. Patients with self reported risk factors for stroke were largely unaware of their increased risk. Only 7.5% of at risk patients acquired their stroke information from the medical profession. CONCLUSIONS: Public knowledge about stroke is good. However, stroke patients access acute services poorly. At risk patients have limited awareness of their increased risk. A campaign should target people at risk, reinforcing the diagnosis of stroke and access to medical services

Cancer risk in second degree relatives of children with soft tissue sarcoma.

The risk of cancer in the second degree relatives of a population-based series of children with soft tissue sarcoma was studied in relation to (i) various characteristics in these relatives, (ii) certain clinical features in the index children previously identified as risk factors for cancer in their first degree relatives. Overall there was a non-significant deficit of cancers in the second degree relatives (RR = 0.88) and cancer risk was unrelated to type or site of cancer, type of relative, or to risk factors in the index case. The findings indicate that although the families investigated may include a proportion with the Li-Fraumeni cancer family syndrome, the increased cancer risk already reported in the first degree relatives does not extent to second degree relatives in general