Extension of Load Follow Capability of a PWR Reactor by Optimal Control

The problem of extending that part of the fuel life cycle during which a reactor is capable of sustaining load-follow operation is formulated as an optimal control problem. A two-node model representation of pressurized water reactor dynamics is used, leading to a set of non-linear ordinary differential equations. Differential Dynamic Programming is used to solve directly the resulting nonlinear optimization problem and obtain the trajectories of soluble boron concentration and control rod insertion. Results of computations performed for a reference reactor are presented, showing how the optimal control policy stretches the capability of the reactor to follow an average daily load curve towards the end of the fuel life cycle.     

Therapeutic change principles: Are commonalities more apparent than real?

Comments that some of the examples of shared change principles that M. R. Goldfried (see record 1981-28393-001) offers illustrate rather fundamental incompatibilities among the therapies. Clinical strategies involving new corrective experiences and direct feedback are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Familial subtypes of depression: a clinical view

The clinical workup of 238 unipolar depressives were subdivided according to immediate family history. Pure depressives (with only depression in the family) typically have an illness involving more endogenous features and chronicity. Depression spectrum patients (with only alcoholism or sociopathy in first-degree relatives) have the mildest illness. Sporadic depression (with a negative family history) is associated with an intermediate severity. Premorbid unstable personality characteristics are more common to the spectrum patients. Sporadic patients have the least personality difficulties. While these differences are definite, they are not large enough to justify separation of unipolar depression into subsyndromes dependent on symptom differences. Rather, family history seems to exert its effect most strongly on the distinctive premorbid personality characteristics of the 3 groups.     

An automated tissue preclassification approach for telepathology: implementation and performance analysis

Telepathology is generally defined as the use of telecommunications technologies in the practice of anatomic or surgical pathology. In the usual telepathology scenario, a remotely located pathologist views images of tissues samples in order to render a diagnosis of the biopsy. Some telepathology systems involve interactive remote control of a microscope-based imaging system which delivers diagnostic quality imagery to the remote pathologist. The usefulness of such interactive systems depends on minimizing the end-to-end delays involved in controlling the robotic microscope, manipulating the tissue sample, and acquiring and transmitting the high-resolution image. An approach to minimizing end-to-end delay involves adding "intelligence" to the image acquisition system so that it can gather, classify, rank, and transmit diagnostically useful images in a semiautonomous fashion. In this research, we develop image analysis and ranking techniques which can improve the end-to-end performance of a robotic telepathology imaging system. Our semiautonomous image collection system uses morphological techniques to extract seed points for suspicious regions, a novel region growing algorithm to segment the regions of interest, and heuristically motivated expert system ranking techniques to select diagnostically relevant "next-step" image acquisitions. Diagnostic relevance of our segmentation and ranking algorithms is established via subjective and objective testing of the system. In subjective testing, pathologists Agree or Strongly Agree that all segmented regions are diagnostically relevant with probability greater than 0.75. In objective testing, 84% of "next-step" images acquired by our algorithms coincide with the areas most likely to be chosen by a pathologist.     

Recombinant hepatitis A virus antigen: improved production and utility in diagnostic immunoassays

Hepatitis A virus (HAV) immunoassays use cell culture-derived HAV antigen to detect HAV-specific antibodies. The current method of production of HAV antigen in tissue culture is time-consuming and expensive. We previously expressed the HAV open reading frame in recombinant vaccinia viruses (rV-ORF). The recombinant HAV polyprotein was accurately processed and was assembled into subviral particles. These particles were bound by HAV-neutralizing antibodies and were able to elicit antibodies which were detected by commercial immunoassays. The present investigation compared the production of HAV antigen by standard tissue culture methods to the production of HAV antigen with the recombinant vaccinia virus system. In addition, HAV and rV-ORF antigens were assessed for their utility in diagnostic immunoassays. Serum or plasma samples from HAV antibody-positive and antibody-negative individuals were evaluated by immunoassay that used either HAV or rV-ORF antigen. All samples (86 of 86) in which HAV antibody was detected by a commercial enzyme-linked immunosorbent assay (ELISA) also tested positive by the recombinant antigen-based immunoassay (VacRIA). Similarly, all samples (50 of 50) that were HAV antibody negative also tested negative by the VacRIA. The lower limit of detection of HAV antibody was similar among immunoassays with either HAV or rV-ORF antigen. Thus, in the population studied, the sensitivity and specificity of the VacRIA were equivalent to those of the commercial ELISA. Since production of recombinant antigen is faster and less expensive than production of traditional HAV antigen, the development of diagnostic HAV antibody tests with recombinant HAV antigen appears warranted.     

Alcoholism and drug abuse in three groups--bipolar I, unipolars and their acquaintances

OBJECTIVE: Previous work has shown that manic-depressive illness and alcohol abuse are linked. This study further explores the relationship of alcohol and drug abuse in bipolar I patients and unipolar depressives and a comparison group obtained through the acquaintance method. METHOD: Diagnosis was accomplished according to Research Diagnostic Criteria (RDC): controls = 469; bipolars = 277; unipolar depressives = 678. Systematic data were gathered using the SADS on lifetime and current drug abuse and alcoholism. Both patients and comparison subjects were then followed prospectively for 10 years. First degree family members were interviewed using the RDC family history method. RESULTS: The group of bipolar patients and the group of unipolar patients had higher rates of drug and alcohol abuse than the comparison group when primary and secondary affective disorder patients were combined. However, primary unipolar patients did not have higher rates of alcohol or drug abuse than the comparison group. In contrast, primary bipolar patients had higher rates of alcoholism, stimulant abuse, and ever having abused a drug than the primary unipolar group and the control group. In an evaluation of the bipolar patients, drug abusers were significantly younger at intake and had a significantly younger age of onset of bipolar disorder. There was a significant increase in family history of mania or schizoaffective mania in the drug-abusing bipolar patients as compared to the non-abusing bipolar patients. LIMITATION: As in all adult samples of patients with affective illness, the chronology of alcohol and substance problems vis-à-vis the onset of illness was determined retrospectively. CONCLUSIONS: (1) Alcoholism and drug abuse are more frequent in bipolar than unipolar patients. (2) The drug abuse of bipolar patients tends toward the abuse of stimulant drugs. (3) In a bipolar patient, familial diathesis for mania is significantly associated with the abuse of alcohol and drugs. (4) More provocatively, these findings suggest the hypothesis of a common familial-genetic diathesis for a subtype of bipolar I, alcohol and stimulant abuse. CLINICAL IMPLICATIONS: The present analyses, coupled with two previous ones from the CDS, suggest that drug abuse may precipitate an earlier onset of bipolar I disorder in those who already have a familial predisposition for mania. Furthermore, in dually diagnosed patients with manic-depressive and alcohol/stimulant abuse history, mood stabilization of the bipolar disorder represents a rational approach to control concurrent alcohol and drug problems, and should be studied in systematic controlled trials.     

The effect of gender and age at onset of depression on mortality

BACKGROUND: Depression has a marked negative impact on geriatric patient mortality and morbidity. The risk factors and exact reasons for these effects are not well understood. METHOD: Seeking to better define the factors, we retrospectively analyzed the effects of gender and age at onset of affective disorder in a naturalistic study of 192 geriatric patients consecutively admitted to a large midwestern tertiary care center between 1980 and 1987 for the treatment of unipolar depression. RESULTS: After controlling for age at index admission, patients with an onset of depression before age 40 suffered significantly (p < .05) less mortality in follow-up than those with onset after age 40. When effects of gender are examined, the effects of age at onset are most profound in women, with a threefold increase in the rate of death in the cohort with age at onset of depression after 70 years when compared to those with onset before age 40. CONCLUSION: These results and those of others suggest that depressed elderly women with no previous history of affective disorder are at a markedly increased risk compared with elderly women with a history of affective illness for morbidity and mortality and that a significant proportion of elderly depressed patients are admitted to a psychiatric hospital for a depression that is secondary to serious medical illness.     

Thermally stimulated current in SiO2

Thermally stimulated current (TSC) techniques provide information about oxide-trap charge densities and energy distributions in MOS (metal-oxide-semiconductor) capacitors exposed to ionizing radiation or high-field stress that is difficult or impossible to obtain via standard capacitance–voltage or current–voltage techniques. The precision and reproducibility of measurements through repeated irradiation/TSC cycles on a single capacitor is demonstrated with a radiation-hardened oxide, and small sample-to-sample variations are observed. A small increase in E′_δ center density may occur in some non-radiation-hardened oxides during repeated irradiation/TSC measurement cycles. The importance of choosing an appropriate bias to obtain accurate measurements of trapped charge densities and energy distributions is emphasized. A 10 nm deposited oxide with no subsequent annealing above 400°C shows a different trapped-hole energy distribution than thermally grown oxides, but a similar distribution to thermal oxides is found for deposited oxides annealed at higher temperatures. Charge neutralization during switched-bias irradiation is found to occur both because of hole-electron annihilation and increased electron trapping in the near-interfacial SiO₂. Limitations in applying TSC to oxides thinner than 5 nm are discussed.     

Analysis of Mission-Oriented Systems

Several measures of system reliability that are applicable to a mission-oriented or time-dependent system are defined: 1) the probability that the system is in a given state at the end of a given mission phase; 2) the probability density function of the random variable time spent in a state, given that the system has just transited into that state; 3) the probability of mission success. Equations for 1)-3) are derived, and an application of the formulas performed for the Naval Air Development Center, Johnsville, Pa., is discussed.