Search PubMed⌕ Search

Biomedical subjects

Q Ma

Publications and source records attributed to Q Ma.

152 records · Page 9Linked to original sources
PubMed1988

Modeling the process of problem-solving by associative networks capable of improving the performance.

In this paper a model of neural network underlying arithmetic problem-solving is described. Memory models of procedural memory, semantic memory, and working memory, which are necessary to represent the process of the problem-solving, are constructed within a framework of a model of associative processor, HASP, proposed by one of the authors (Hirai 1983). Performance of the model has been simulated on a digital computer. By memorizing primitive knowledge of addition of two digits such as 6 + 8 = 14 in the semantic memory and procedural knowledge for the control of the process of adding in the procedural memory, the model can perform addition of multiple numbers with multiple digits. By making explicit serial associations between consecutive procedural steps, the performance of the model can be improved, because a current procedural step primes the next one. In addition, if a preceding procedural step is a subset of the next one, merging between the two steps occurs. The performance can be improved about 20% by these priming and merging. By memorizing incorrect procedures, the model can generate four kinds of bugs of addition which were observed in children's performance.

Computer Simulation↗
PubMed1986

[One stage resection of esophageal cancer and pulmonary bulla--a report of three patients].

Since 1982, three patients with esophageal cancer complicated with pulmonary bullae have been treated by operation on the esophagus and lung in one performance: In all the patients, the bullae were on the same side of the operation. The esophageal or cardiac cancer was resected first, then the bulla was treated. The site of esophago-gastric anastomosis was reinforced by the greater omentum. For mid-upper esophageal cancer, cervical anastomosis was done in order to avoid infection or leakage. In the third patient, pyopneumothorax occurred after wedge resection of a large bulla in the right upper lung and the surrounding tissues. The patient survived after timely drainage and medical management. The extent of resection for pulmonary bulla (bulla, segment or lobe) depends on the location, shape, size and number of the bullae and the pathological change in the surrounding tissues. We suggest that the indications: Cardio-pulmonary functions of the patient be stage II or better, even with mild emphysema so as they can tolerate anesthesia and surgery. Pulmonary function can be compensated after the lesion is removed, otherwise it is taken as a contraindication. The one stage removal of two foci makes it possible to avoid postoperative complications.

Cardia↗
PubMedDate not supplied

Coupling CD28 co-stimulation to immunoglobulin T-cell receptor molecules: the dynamics of T-cell proliferation and death.

Immunoglobulin T-cell receptor (IgTCR) molecules are potentially potent immune response modifiers because they allow T cells to bypass tolerance. Tolerance to self antigens has been one of the major barriers to the development of effective adoptive immunotherapies for treating cancer. In vitro studies in several laboratories have shown that cross-linking IgTCR molecules with the target antigen leads to cytolytic activity, cytokine release, and T-cell proliferation in model systems. However, many of these studies have used established T-cell lines rather than normal T cells or indirect assays of cytotoxicity, proliferation, and cytokine release. We have sought to establish the validity of these model systems while developing more effective adoptive immunotherapies using normal human T cells. In the present study the activation of T-cell proliferation after IgTCR cross-linking was evaluated. The results show that, in addition to IgTCR signals, CD28 costimulation is required to induce expansions of normal peripheral blood mononuclear cell-derived T cells. Signals from IgTCR alone can induce transient cell division, but they do not induce the prolonged polyclonal expansions that are characteristic of native immune responses. Very strong IgTCR signals could circumvent the CD28 requirement, but only at levels that are unlikely to be physiologically relevant. CD28 costimulation also suppressed the deletion of tumor-reactive subclones by activation-induced cell death. These studies confirm the importance of CD28 costimulation to the proliferation of IgTCR-modified human T cells, a key feature of an effective, reconstructed antitumor response.

Antibody Affinity↗