1,833 research outputs found
Keyword binding as a method of reducing the length of indexes in library catalogues (based on the experience of Digital Library of Wielkopolska)
This paper presents a relatively simple and cheap method for shortening the subject indexes in library catalogs. The method involves taking a set of several dozen general concepts, characterized by a low semantic awareness barrier. Built around these words are subindexes made up of the words which appear in descriptions containing a particular general concept. The effectiveness of the method was studied by analyzing the content of fragments of subject indexes of the NUKAT central catalog of Polish libraries, the University Library in Poznań and the Library of Congress. Compared with the subject headings language method, this method reduces the length of an index by an average of two-thirds, and makes it significantly easier for readers to navigate the vocabulary used by the cataloger. This method has been developed for the needs of Digital Library of Wielkopolska, and will probably be used in all regional digital libraries in Poland
Keyword binding as a method of reducing the length of indexes in library catalogues (based on the experience of Digital Library of Wielkopolska)
This paper presents a relatively simple and cheap method for shortening the subject indexes in library catalogues. The method involves taking a set of several dozen general concepts, characterized by a low semantic awareness barrier. Built around these words are subindexes made up of the words which appear in descriptions containing a particular general concept. The effectiveness of the method was studied by analyzing the content of fragments of subject indexes of the NUKAT central catalogue of Polish libraries, the University Library in Poznań and the Library of Congress. Compared with the subject headings language method, this method reduces the length of an index by an average of two-thirds, and makes it significantly easier for readers to navigate the vocabulary used by the cataloger. This method has been developed for the needs of Digital Library of Wielkopolska, and will probably be used in all regional digital libraries in Poland.Artykuł przedstawia stosunkowo prostą i tanią metodę skracania indeksów rzeczowych w katalogach bibliotecznych. Polega ona na przyjęciu zestawu kilkudziesięciu pojęć ogólnych - charakteryzujących się niską barierą świadomości semantycznej. Wokół tych słów budowane są subindeksy złożone ze słów występujących w opisach zawierających dane pojęcie ogólne. Skuteczność metody badano, analizując zawartość fragmentów indeksów przedmiotowych centralnego katalogu bibliotek polskich NUKAT, Biblioteki Uniwersyteckiej w Poznaniu i Biblioteki Kongresu. Metoda ta w porównaniu z metodą języka haseł przedmiotowych średnio trzykrotnie skraca długość indeksu i znacznie ułatwia czytelnikowi rozeznanie w użytym przez katalogera słownictwie. Została opracowana dla potrzeb Wielkopolskiej Biblioteki Cyfrowej i prawdopodobnie będzie stosowana we wszystkich regionalnych bibliotekach cyfrowych w Polsce
Sleep Disruption Medical Intervention Forecasting (SDMIF) Module for the Integrated Medical Model
The NASA Integrated Medical Model (IMM) assesses the risk, including likelihood and impact of occurrence, of all credible in-flight medical conditions. Fatigue due to sleep disruption is a condition that could lead to operational errors, potentially resulting in loss of mission or crew. Pharmacological consumables are mitigation strategies used to manage the risks associated with sleep deficits. The likelihood of medical intervention due to sleep disruption was estimated with a well validated sleep model and a Monte Carlo computer simulation in an effort to optimize the quantity of consumables. METHODS: The key components of the model are the mission parameter program, the calculation of sleep intensity and the diagnosis and decision module. The mission parameter program was used to create simulated daily sleep/wake schedules for an ISS increment. The hypothetical schedules included critical events such as dockings and extravehicular activities and included actual sleep time and sleep quality. The schedules were used as inputs to the Sleep, Activity, Fatigue and Task Effectiveness (SAFTE) Model (IBR Inc., Baltimore MD), which calculated sleep intensity. Sleep data from an ISS study was used to relate calculated sleep intensity to the probability of sleep medication use, using a generalized linear model for binomial regression. A human yes/no decision process using a binomial random number was also factored into sleep medication use probability. RESULTS: These probability calculations were repeated 5000 times resulting in an estimate of the most likely amount of sleep aids used during an ISS mission and a 95% confidence interval. CONCLUSIONS: These results were transferred to the parent IMM for further weighting and integration with other medical conditions, to help inform operational decisions. This model is a potential planning tool for ensuring adequate sleep during sleep disrupted periods of a mission
Organosulfate Formation in Biogenic Secondary Organic Aerosol
Organosulfates of isoprene, α-pinene, and β-pinene have recently been identified in both laboratory-generated and ambient secondary organic aerosol (SOA). In this study, the mechanism and ubiquity of organosulfate formation in biogenic SOA is investigated by a comprehensive series of laboratory photooxidation (i.e., OH-initiated oxidation) and nighttime oxidation (i.e., NO3-initiated oxidation under dark conditions) experiments using nine monoterpenes (α-pinene, β-pinene, d-limonene, l-limonene, α-terpinene, γ-terpinene, terpinolene, Δ3-carene, and β-phellandrene) and three monoterpenes (α-pinene, d-limonene, and l-limonene), respectively. Organosulfates were characterized using liquid chromatographic techniques coupled to electrospray ionization combined with both linear ion trap and high-resolution time-of-flight mass spectrometry. Organosulfates are formed only when monoterpenes are oxidized in the presence of acidified sulfate seed aerosol, a result consistent with prior work. Archived laboratory-generated isoprene SOA and ambient filter samples collected from the southeastern U.S. were reexamined for organosulfates. By comparing the tandem mass spectrometric and accurate mass measurements collected for both the laboratory-generated and ambient aerosol, previously uncharacterized ambient organic aerosol components are found to be organosulfates of isoprene, α-pinene, β-pinene, and limonene-like monoterpenes (e.g., myrcene), demonstrating the ubiquity of organosulfate formation in ambient SOA. Several of the organosulfates of isoprene and of the monoterpenes characterized in this study are ambient tracer compounds for the occurrence of biogenic SOA formation under acidic conditions. Furthermore, the nighttime oxidation experiments conducted under highly acidic conditions reveal a viable mechanism for the formation of previously identified nitrooxy organosulfates found in ambient nighttime aerosol samples. We estimate that the organosulfate contribution to the total organic mass fraction of ambient aerosol collected from K-puszta, Hungary, a field site with a similar organosulfate composition as that found in the present study for the southeastern U.S., can be as high as 30%
Development of a Design Tool for Flow Rate Optimization in the Tata Swach Water Filter
When developing a first-generation product, an iterative approach often yields the shortest time-to-market. In order to optimize its performance, however, a fundamental understanding of the theory governing its operation becomes necessary. This paper details the optimization of the Tata Swach, a consumer water purifier produced for India. The primary objective of the work was to increase flow rate while considering other factors such as cost, manufacturability, and efficacy. A mathematical model of the flow characteristics through the filter was developed. Based on this model, a design tool was created to allow designers to predict flow behavior without prototyping, significantly reducing the necessity of iteration. Sensitivity analysis was used to identify simple ways to increase flow rate as well as potential weak points in the design. Finally, it was demonstrated that maximum flow rate can be increased by 50% by increasing the diameter of a flow-restricting feature while simultaneously increasing the length of the active purification zone. This can be accomplished without significantly affecting cost, manufacturability, and efficacy.MIT Tata Center for Technology and Desig
SRG110 Stirling Generator Dynamic Simulator Vibration Test Results and Analysis Correlation
The U.S. Department of Energy (DOE), Lockheed Martin (LM), and NASA Glenn Research Center (GRC) have been developing the Stirling Radioisotope Generator (SRG110) for use as a power system for space science missions. The launch environment enveloping potential missions results in a random input spectrum that is significantly higher than historical radioisotope power system (RPS) launch levels and is a challenge for designers. Analysis presented in prior work predicted that tailoring the compliance at the generator-spacecraft interface reduced the dynamic response of the system thereby allowing higher launch load input levels and expanding the range of potential generator missions. To confirm analytical predictions, a dynamic simulator representing the generator structure, Stirling convertors and heat sources were designed and built for testing with and without a compliant interface. Finite element analysis was performed to guide the generator simulator and compliant interface design so that test modes and frequencies were representative of the SRG110 generator. This paper presents the dynamic simulator design, the test setup and methodology, test article modes and frequencies and dynamic responses, and post-test analysis results. With the compliant interface, component responses to an input environment exceeding the SRG110 qualification level spectrum were all within design allowables. Post-test analysis included finite element model tuning to match test frequencies and random response analysis using the test input spectrum. Analytical results were in good overall agreement with the test results and confirmed previous predictions that the SRG110 power system may be considered for a broad range of potential missions, including those with demanding launch environments
Fatigue Crack Growth Behavior Evaluation of Grainex Mar-M 247 for NASA's High Temperature, High Speed Turbine Seal Test Rig
The fatigue crack growth behavior of Grainex Mar-M 247 is evaluated for NASA s Turbine Seal Test Facility. The facility is used to test air-to-air seals primarily for use in advanced jet engine applications. Because of extreme seal test conditions of temperature, pressure, and surface speeds, surface cracks may develop over time in the disk bolt holes. An inspection interval is developed to preclude catastrophic disk failure by using experimental fatigue crack growth data. By combining current fatigue crack growth results with previous fatigue strain-life experimental work, an inspection interval is determined for the test disk. The fatigue crack growth life of the NASA disk bolt holes is found to be 367 cycles at a crack depth of 0.501 mm using a factor of 2 on life at maximum operating conditions. Combining this result with previous fatigue strain-life experimental work gives a total fatigue life of 1032 cycles at a crack depth of 0.501 mm. Eddy-current inspections are suggested starting at 665 cycles since eddy current detection thresholds are currently at 0.381 mm. Inspection intervals are recommended every 50 cycles when operated at maximum operating conditions
The fecal presence of enterotoxin and F4 genes as an indicator of efficacy of treatment with colistin sulfate in pigs
Background :
Enterotoxigenic Escherichia coli (ETEC) strains producing multiple enterotoxins are important causes of post-weaning diarrhea (PWD) in pigs. The aim of the present study was to investigate the fecal presence of ETEC enterotoxin as well as F4 and F18 genes as an indicator of colistin sulfate (CS) efficacy for treatment of PWD in pigs. Forty-eight piglets were weaned at the age of 21 days, and were divided into four groups: challenged treated, challenged untreated, unchallenged treated, and unchallenged untreated. Challenge was performed using 109 CFU of an ETEC: F4 strain, and treatment was conducted using oral CS at the dose of 50,000 IU/kg. The fecal presence of genes encoding for STa, STb, LT, F4 and F18 was detected using PCR.
Results :
The PCR amplification of ETEC virulence genes showed that nearly 100% of pigs excreted genes encoding for STa and STb toxins in the feces before the challenge. These genes, in the absence of the gene encoding F4, were considered as a marker for F4-negative ETEC. One day after ETEC: F4 oral challenge pigs in the two challenged groups excreted the genes encoding LT and F4 in the feces. These genes were considered as a marker for F4-positive ETEC. However, the gene encoding F18 was not detected in any fecal samples of the 4 groups throughout the experiment. After only 3 days of successive oral treatment with CS, a significant reduction in both the F4-positive and negative ETEC populations was observed in the challenged treated group compared to the challenged untreated group (p < 0.0001).
Conclusions :
Our study is among the first to report that under controlled farming conditions, oral CS treatment had a significant effect on both fecal F4-positive and F4-negative ETEC in pigs. However, CS clinical efficiency was correlated with non-detection of F4-positive ETEC in the feces. Furthermore the fecal presence of F4-negative ETEC was not associated with clinical symptoms of post-weaning diarrhea in pigs
- …
