Characterization of stochastic processes which stabilize linear companion form systems

AbstractThe class of stochastic processes is characterized which, as multiplicative noise with large intensity, stabilizes a linear system with companion form d×d-matrix. This includes the characterization of parametric noise which stabilizes the damped inverse pendulum. The proof yields also an expansion of the top Lyapunov exponent in terms of the noise intensity as well as a criterion for a stationary diffusion process permitting a stationary integral and it shows that stabilizing noise averages the Lyapunov spectrum

A Dynamic Programming Approach to De Novo Peptide Sequencing via Tandem Mass Spectrometry

The tandem mass spectrometry fragments a large number of molecules of the same peptide sequence into charged prefix and suffix subsequences, and then measures mass/charge ratios of these ions. The de novo peptide sequencing problem is to reconstruct the peptide sequence from a given tandem mass spectral data of k ions. By implicitly transforming the spectral data into an NC-spectrum graph G=(V,E) where |V|=2k+2, we can solve this problem in O(|V|+|E|) time and O(|V|) space using dynamic programming. Our approach can be further used to discover a modified amino acid in O(|V||E|) time and to analyze data with other types of noise in O(|V||E|) time. Our algorithms have been implemented and tested on actual experimental data.Comment: A preliminary version appeared in Proceedings of the 11th Annual ACM-SIAM Symposium on Discrete Algorithms, pages 389--398, 200

Oxygen-vacancy-mediated Negative Differential Resistance in La and Mg co-substituted BiFeO3 Thin Film

The conductive characteristics of Bi0.9La0.1Fe0.96Mg0.04O3(BLFM) thin film are investigated at various temperatures and a negative differential resistance (NDR) is observed in the thin film, where a leakage current peak occurs upon application of a downward electric field above 80 oC. The origin of the NDR behavior is shown to be related to the ionic defect of oxygen vacancies (VO..) present in the film. On the basis of analyzing the leakage mechanism and surface potential behavior, the NDR behavior can be understood by considering the competition between the polarized distribution and neutralization of VO..

Water and Sediment Discharge from Small Mountainous Rivers, Taiwan: The Roles of Lithology, Episodic Events, and Human Activities

Taiwan’s natural setting creates highly vulnerable watersheds whose rivers discharge disproportionately large quantities of sediment to the coastal ocean. The 16 Taiwanese rivers analyzed in this article discharge ∼180 Mt yr-1 of sediment to the coastal ocean, although totals over the past 20 years have varied between 16 and 440 Mt yr-1. The mean annual sediment yield of 9500 t km-2 yr-1 for the 16 rivers is 60-fold greater than the global yield of 150 t km-2 yr-1, but mean yields for the individual rivers vary by more than 2 orders of magnitude, from 500 to 71,000 t km-2 yr-1. Most sediment erosion and delivery occur in response to typhoon-generated floods, as evidenced by the fact that \u3e75% of the long-term flux occurs in \u3c 1% of the time, about one-third of which reaches hyperpycnal concentrations. Detailed analysis of the 16 watersheds reveals little evidence of any single environmental factor that controls sediment load. The Erren, the highest-yield river on Taiwan, drains an erodible but low-gradient watershed with relatively low runoff. In contrast, three east coast rivers, the Hoping, the Hualien, and the Beinan, have high sediment yields that may be explained by relatively frequent earthquakes coupled with high runoff. Farming and urbanization also have elevated sediment yields in eastern watersheds, whereas Holocene sediments buried in the Taiwan Strait suggest that present-day sediment loads of the western rivers may be no higher than prehuman levels

Hyperpycnal Discharge of Fluvial Sediment to the Ocean: Impact of Super‐Typhoon Herb (1996) on Taiwanese Rivers

Hyperpycnal events (when suspended sediment concentrations exceed 40 g/L) occur in small‐ and medium‐sized rivers throughout the world but are particularly common in Taiwan; they are often related to landslides or debris flows initiated and transported by typhoon floods. Super‐Typhoon Herb, which swept across Taiwan on July 31–August 2, 1996, triggered floods and landslides throughout the southern part of the island. Sediment concentrations in at least seven rivers (Taan, Choshui, Pachang, Erhjen, Tsengwen, Kaoping, and Peinan) approached or exceeded 40 g/L. Calculated sediment discharged from nine rivers (these seven as well as the Wu and Houlung, neither of which apparently reached hyperpycnal concentrations) during these 3 d was 217 million tons (MT)—most of it on August 1—of which ∼80% was discharged at hyperpycnal concentrations. Presumably, most of the sediments discharged by the Peinan River (to the southeast) and the Kaoping, Erhjen, Tsengwen, and Pachang rivers (to the southwest) were transported directly to the Huatong Basin and the South China Sea (via the Penghu Canyon system), respectively. The bulk of the typhoon‐derived sediment (142 MT), however, was discharged to the northwest (primarily by the Choshui River), and its fate remains unknown. It may have ultimately reached the Penghu Canyon system and thereby the South China Sea, but more probably it was transported northward (via the Taiwan Warm Current) toward China, the East China Sea, or (perhaps) the Okinawa Trough

Absorption coefficients in light oil scrubbers

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1941.Includes bibliographical references (leaf 91).by Edward Colin Forbes, John Yü-Ling Kao.M.S

Characterization of the Bacterium Associated With Ratoon Stunting Disease and the Effects of the Disease on Water Relations of Sugarcane.

Part I. Microcolonies of a filamentous, branched organism were observed by phase-contrast and interference-contrast microscopy in vascular extracts from internodes of sugarcane with ratoon stunting disease. The microcolonies were present in a matrix extracted from the xylem vessels of internodes by negative pressure. Matrices and microcolonies were not found in sugarcane known to be free of the disease. Electron microscopy revealed branched chains of cells with septa and mesosomes. The individual cells of the filaments were characteristic of the previously described coryneform bacterium associated with the disease. Vascular extracts from one- or two-node cuttings of diseased cane did not reveal matrices of microcolonies but did contain the individual cells or short branched chains of the organism. The filamentous spiderlike morphology of the microcolonies and true branching suggest a relation to the Actinomycetales. Part II. Freshly sectioned tissues of sugarcane with ratoon stunting disease were examined with the scanning electron microscope. The RSD-associated bacterium was recognized by its diameter, pleomorphism and xylem association. It commonly occupied the protoxylem and metaxylem vessels. The bacterium was observed in the gaps between secondary wall thickenings of xylem vessels and also adhering to the secondary wall. The lacunae, tracheids and xylem parenchyma cells also were invaded by the bacterium. The lumen of some infected xylem elements was filled with a dense network of bacterial cells. Remnants of a supporting matrix were observed in some of these lumina. Unicellular forms were most frequently observed; however, swollen forms, filamentous branching forms and microcolonies consisting of tightly aggregated bacterial cells which I have previously described from extracts of diseased tissue also were observed. Part III. The RSD-associated bacterium was extracted from diseased sugarcane and purified by differential and density gradient centrifugation. Cells were sonicated, DNA was extracted, and walls were prepared by enzymatic digestion. After cell wall hydrolysis, sugars and amino acids were analyzed. Fucose and rhamnose were the major sugar components. Lysine, ornithine, alanine, glutamic acid, and glycine were presumed to make up the peptidoglycan tetrapeptide and linkage. The Tm of the DNA was determined and the G + C content calculated at 60 moles %. These results are characteristic of the family Actinomycetaceae and more specifically the genus Actinomyces. Part IV. The transpiration rate of detached sugarcane shoots with ratoon stunting disease was significantly lower than that of detached healthy shoots. Apparent root pressure also decreased in diseased plants. Intact plant transpiration was measured by weight loss experiments from well watered pots contaning healthy or diseased canes which were unwatered for 7 days. Diffusive resistance of leaves to water vapor loss was measured daily. Diseased plants had a significantly lower transpiration rate than healthy plants; however, no significant differences in diffusive resistance between healthy and diseased plants was detected. This implied that the stomatal behavior of the plants was not affected by the disease, and that the lower transpiration rate in diseased plants appeared to be the consequence of the physical plugging of the xylem vessels by the RSD-associated bacterium and the gel matrices which were described previously