Control design based on a linear state function observer

A control design method based on a linear state function observer is proposed. The method is a semi-inverse design procedure in that the control law is not designed before the observer system, but is a result of the observer design. However, the observer design is not completely independent of the control design, but seeks to yield a feedback signal that is close to a prescribed control law. First, the observer design problem is considered as the reconstruction of a linear function of the state vector. The linear state function to be reconstructed is the given control law. Then, based on the derivation for linear state function observers, the observer design is formulated as a parameter optimization problem. The optimization objective is to generate a matrix that is close to the given feedback gain matrix. Based on that matrix, the form of the observer and a new control law can be determined. The semi-inverse design procedure can yield a reduced-order observer with dimension considerably smaller than that of the system. Two numerical examples are used to demonstrate the proposed design procedure.     

Effective immunity to dental caries: enhancement of salivary anti-Streptococcus mutans antibody responses with oral adjuvants

In the present study, we compared the ability of the soluble adjuvants concanavalin A (ConA), muramyl dipeptide (MDP), and peptidoglycan (PG) to enhance immune responses to orally administered particulate antigens of Streptococcus mutans 6715 in gnotobiotic rats. The isotype and levels of antibody in saliva and in serum from experimental rats were determined by an enzyme-linked immunosorbent assay using S. mutans whole cells (WC) as the coating antigen. The specificities of salivary and serum immunoglobulin A (IgA) antibodies to particulate S. mutans antigens, lipoteichoic acid, S. mutans serotype g carbohydrate, and dextran were also determined. When 50 micrograms of ConA was used as the oral adjuvant with S. mutans 6715 WC immunogen, a slight enhancement of immune responses was obtained. A higher dose of ConA suppressed humoral responses to the immunogen. Enhanced immune responses, especially of the IgA isotype, in both serum and saliva were induced in gnotobiotic rats given MDP and either S. mutans 6715 WC or purified cell walls (CW) by gastric intubation. Elevated IgA antibody levels to CW, lipoteichoic acid, and carbohydrate were observed in rats given S. mutans WC and MDP by gastric intubation, whereas oral immunization with S. mutans CW and MDP resulted in higher antibody levels to CW and carbohydrate and lower levels to lipoteichoic acid when compared with the antibody levels in rats given antigen alone. Rats orally immunized with either S. mutans WC or CW and MDP and challenged with virulent S. mutans 6715 exhibited significantly (P less than or equal to 0.05) lower plaque scores, numbers of viable S. mutans in plaque, and caries scores than did rats immunized with antigen alone or in infected-only controls. In another series of experiments, a PG fraction derived from S. mutans 6715 CW was assessed for adjuvant properties. The oral administration of PG and either S. mutans WC or CW induced good salivary and serum IgA antibody responses. The specificity of the antibodies was similar to that obtained in rats given antigen and MDP. Rats receiving either S. mutans WC or CW and PG and challenged with virulent S. mutans 6715 had lower plaque scores, fewer numbers of viable S. mutans in plaque, and lower caries activity than did infected rats receiving S. mutans WC or CW immunogen alone. These results provide evidence that soluble adjuvants derived from the gram-positive bacterial CW, e.g., MDP and PG, are effective oral adjuvants and augment IgA immune responses to particulate S. mutans antigens which are protective against the mucosally associated disease, dental caries.     

The effect of an oxide layer on the ohmicity of contacts to amorphous silicon

Surface oxide layers on CVD films of amorphous silicon can cause the metallic contacts to the films to be non-ohmic. Dipping an amorphous silicon sample in a solution of hydrofluoric acid prior to electrode deposition removes the oxide layer and permits the formation of ohmic contacts.     

Chemical, Physical, and Sensory Properties of a Sweet Potato French-Fry Type Product During Frozen Storage

Chemical, physical, and sensory properties of a sweet potato Frenchfry type product were determined after 0, 3, 6, 9, and 12 months frozen storage. Analyses included measurements of dry matter, sugars, alcohol insoluble solids, carotene, vitamin C, color, texture and sensory panel scores for color, flavor and texture. Few changes were observed except for an appreciable loss (58%) in vitamin C and an apparent increase in carotene (27%). A partial drying treatment before freezing increased the rate of ascorbic acid loss. For the fried product, no appreciable storage-induced changes were noted in the sensory scores for color, flavor and texture thus indicating that the product had good stability in frozen storage.     

Effect of Curing on Sensory Properties and Carbohydrate Composition of Baked Sweet Potatoes

In a two-year study, the flavor and texture profiles and carbohydrate composition of cured, baked‘Jewels’sweet potatoes were compared to baked, uncured‘Jewels’sweet potatoes. Curing increased the rate of production of flavor notes and only slightly influenced development of “moist” mouthfeel. Given sufficient time after harvest, baked, cured roots were indistinguishable from baked, uncured roots. Carbohydrate content was not a sensitive indicator of post-harvest treatment since no statistically significant differences were detected between cured and uncured roots.     

Ascospore Heat Resistance and Control Measures for Talaromyces flaws Isolated From Fruit Juice Concentrate

Talarotnyces flavus were isolated from fruit juice concentrates in two unrelated spoilage incidences of packaged reconstituted fruit juice. The population of survivors in heated fruit concentrate was 0.6 colony forming units (CFU) per gram. The ellipsoidal ascospores diameters were 4.5 ± 6 μm. Potassium sorbate and sodium benzoate prevented outgrowth of T. flavus, the concentration required was lower when the pH of the growth medium was 3.5 instead of 5.4. Conidia were sensitive to 70% ethanol, but ascospores were resistant. Ascospores required heat activation before maximum outgrowth occurred, the time for activation was less with higher activation temperature. Thermal death rate curves were nonlogarithmic but approached logarithmic death rate at higher temperatures. A calculated thermal destruction rate, using the exponential formula, for 1 log₁₀ was 2–7 min at 90°C depending upon the strain; and the approximate z-value was 10.3°C.     

The role of the fixation location in inhibition of return.

In examining the role of the fixation location in inhibition of return (IOR), 3 experiments were conducted in which an exogenous cue was used to reorient attention following a peripheral cue and before the appearance of a target. However, this cue occurred at either the traditional central fixation location or a nonfixated location. In Exp 1, 10 undergraduates' eye positions were monitored at the 3 different times during the trial (after the onset of the cue at 1 of the target locations; after the onset of the 2nd cue; after the onset of the target). In Exp 2, 16 undergraduates repeated the same procedures as in Exp 1 except that an additional cue was added. In Exp 3, 8 undergraduates repeated the same procedures as in Exp 1 except the placement of the fixation, peripheral, and target locations was altered. The results indicate that reorienting attention to a fixated location results in a significant reduction in the inhibitory effect. The results from the study suggest that IOR could serve as a mechanism that improves the efficiency of visual searches. (PsycINFO Database Record (c) 2010 APA, all rights reserved)