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RIV Framework for Phase Transition Analysis in Compressed Sensing
Oliver James,Heung-No Lee 대한전자공학회 2015 ITC-CSCC :International Technical Conference on Ci Vol.2015 No.6
In this paper, we introduce restricted isometry random variable (RIV) generalizing the restricted isometry constant (RIC) in compressed sensing (CS). For i.i.d. Gaussian encoders, we derive the probability distribution function of the RIV using order statistics and extreme value theory. We show the benefits of the distributions in signal recovery analysis via the critical functions, which predict the RICs of an encoder for various problem sizes. We demonstrate that RIV-based critical functions give precise estimates of the RICs than the previous eigenvalue (EV) -based approaches. We also demonstrate that this precise estimation aids to improve the previous EV-based phase transition analysis in CS.
The Viable but Nonculturable State in Bacteria
Oliver James D. The Microbiological Society of Korea 2005 The journal of microbiology Vol.43 No.1
It had long been assumed that a bacterial cell was dead when it was no longer able to grow on routine culture media. We now know that this assumption is simplistic, and that there are many situations where a cell loses culturability but remains viable and potentially able to regrow. This mini-review defines what the 'viable but nonculturable' (VBNC) state is, and illustrates the methods that can be used to show that a bacterial cell is in this physiological state. The diverse environmental factors which induce this state, and the variety of bacteria which have been shown to enter into the VBNC state, are listed. In recent years, a great amount of research has revealed what occurs in cells as they enter and exist in this state, and these studies are also detailed. The ability of cells to resuscitate from the VBNC state and return to an actively metabolizing and culturable form is described, as well as the ability of these cells to retain virulence. Finally, the question of why cells become nonculturable is addressed. It is hoped that this mini-review will encourage researchers to consider this survival state in their studies as an alternative to the conclusion that a lack of culturability indicates the cells they are examining are dead.
Development of an Autonomous Hand Tractor Platform for Philippine Agricultural Operations
Anthony James Bautista,Samuel Oliver Wane,Fredrick Nario,John Lester Torres,Tedheus Eigyef Danao 제어로봇시스템학회 2018 제어로봇시스템학회 국제학술대회 논문집 Vol.2018 No.10
The growing population, low level of mechanization, and climate change puts major constraints onto food production in Philippines’ agriculture. Aside from these, the younger generation are not choosing farming as a career, thus, there is a shortage of labour for farm work. These challenges therefore require innovative and practical solutions. Autonomous navigation as applied in agriculture plays a key role in the advancement of agricultural machineries. Development of agricultural robots became more accessible because of the availability of open source software and hardware. The objective of the research is to develop a platform for autonomous navigation by modifying a walking tractor. Arduino Mega 2560 was used as the main microcontroller and readily available GPS and compass module were used as navigation sensors. Waypoint following test and heading performance test were performed and the results show that the robot can navigate successfully with an inaccuracy of 2 meters from the desired path and a 4 degree RMS heading error was also recorded at a speed of 0.15 m/s. The results from this study can be used as a basis in developing simple autonomous robots which does not require high navigation accuracy such as delivering and carrying loads around the farm.
Day, Ashley P.,Oliver, James D. The Microbiological Society of Korea 2004 The journal of microbiology Vol.42 No.2
Vibrio vulnificus, a Gram-negative bacterium found in estuarine waters, is responsible for over 95% of all seafood-related deaths in the United States. As a result of a temperature downshift to 5$^{\circ}C$, this organism enters the viable but nonculturable (VBNC) state. Changes in the membrane fatty acid (FA) composition of V. vulnificus may be a contributing factor to the ability of this organism to enter into and survive in the VBNC state. This hypothesis was tested by incubating the organism at 5$^{\circ}C$ in arti-ficial sea water and analyzing the cells' FAs during the initial hours of temperature and nutrient down-shift. Prior to downshift, the predominant FAs were 16:0, 16:1 and 18:0. During the first four hours of downshift, statistically significant changes occurred in 15:0, 16:1, 16:0, 17:0, and 18:0. These results indicate that changes in FA composition occur prior to entry of V. vulnificus into the VBNC state, suggesting that the ability to maintain membrane fluidity may be a factor in this physiological response. Cells in which fatty acid synthesis was inhibited did not survive, indicating that active fatty acid metab-olism is essential for entry of cells into the VBNC state.
Tonya C. Bates,James D. Oliver 한국미생물학회 2004 The journal of microbiology Vol.42 No.2
Ingestion of shellfish-associated Vibrio parahaemolyticus is the primary cause of potentially severe gastroenteritis in many countries. However, only Kanagawa phenomenon (hemolysin) positive (KP+) strains of V. parahaemolyticus are isolated from patients, whereas >99% of strains isolated from the environment do not produce this hemolysin (i.e. are KP-). The reasons for these differences are not known. Following a temperature downshift, Vibrio parahaemolyticus enters the viable but nonculturable (VBNC) state wherein cells maintain viability but cannot be cultured on routine microbiological media. We speculated that KP+ and KP- strains may respond differently to the temperature and salinity conditions of seawater by entering into this state which might account for the low numbers of culturable KP+ strains isolated from estuarine waters. The response of eleven KP+ and KP- strains of V. parahaemolyticus following exposure to a nutrient and temperature downshift in different salinities, similar to conditions encountered in their environment, was examined. The strains included those from which the KP+ genes had been selectively removed or added. Our results indicated that the ability to produce hemolysin did not affect entrance into the VBNC state. Further, VBNC cells of both biotypes could be restored to the culturable state following an overnight temperature upshift.
Bates, Tonya C.,Oliver, James D. The Microbiological Society of Korea 2004 The journal of microbiology Vol.42 No.2
Ingestion of shellfish-associated Vibrio parahaemolyticus is the primary cause of potentially severe gas-troenteritis in many countries. However, only Kanagawa phenomenon (hemolysin) positive (KP$\^$+/) strains of V. parahaemolyticus are isolated from patients, whereas >99% of strains isolated from the environment do not produce this hemolysin (i.e. are KP$\^$-/). The reasons for these differences are not known. Following a temperature downshift, Vibrio parahaemolyticus enters the viable but noncultur-able (VBNC) state wherein cells maintain viability but cannot be cultured on routine microbiological media. We speculated that KP$\^$+/ and KP$\^$-/ strains may respond differently to the temperature and salinity conditions of seawater by entering into this state which might account for the low numbers of cul-turable KP$\^$+/ strains isolated from estuarine waters. The response of eleven KP$\^$+/ and KP$\^$-/ strains of V. parahaemolyticus following exposure to a nutrient and temperature downshift in different salinities, similar to conditions encountered in their environment, was examined. The strains included those from which the KP$\^$+/ genes had been selectively removed or added. Our results indicated that the ability to produce hemolysin did not affect entrance into the VBNC state. Further, VBNC cells of both biotypes could be restored to the culturable state following an overnight temperature upshift.
Karen Dyer Blackwell,James D. Oliver 한국미생물학회 2008 The journal of microbiology Vol.46 No.2
While numerous studies have characterized the distribution and/or ecology of various pathogenic Vibrio spp., here we have simultaneously examined several estuarine sites for Vibrio vulnificus, V. cholerae, and V. parahaemolyticus. For a one year period, waters and sediment were monitored for the presence of these three pathogens at six different sites on the east coast of North Carolina in the United States. All three pathogens, identified using colony hybridization and PCR methods, occurred in these estuarine environments, although V. cholerae occurred only infrequently and at very low levels. Seventeen chemical, physical, and biological parameters were investigated, including salinity, water temperature, turbidity, dissolved oxygen, levels of various inorganic nutrients and dissolved organic carbon, as well as total vibrios, total coliforms, and E. coli. We found each of the Vibrio spp. in water and sediment to correlate to several of these environmental measurements, with water temperature and total Vibrio levels correlating highly (P<0.0001) with occurrence of the three pathogens. Thus, these two parameters may represent simple assays for characterizing the potential public health hazard of estuarine waters.