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J C Kimball

Publications and source records attributed to J C Kimball.

11 recordsLinked to original sources
PubMed2004

Aharonov-Bohm effects in entangled molecules.

Molecules which are magnetic and conducting, if suitably entangled (e.g., catenanes and knots) could exhibit Aharonov-Bohm effects which can be viewed as particular examples of a Berry phase. The corrections to the quantum energy levels reflect the entangled geometry of the molecules and, while small (they are proportional to the square of the fine structure constant), may be observable. We illustrate these corrections for a number of catenated and knotted structures. For couplings between the components of a catenane (link), the Aharonov-Bohm corrections are determined by integer-valued linking numbers. For knots, the Aharonov-Bohm correction is proportional to the geometric writhe of the knot.

Journal Article↗
PubMed2001

Chaotic properties of the soft-disk Lorentz gas.

The traditional hard-disk Lorentz gas describes the chaotic motion of a classical point particle through an array of impenetrable disks. Soft-disk modifications of the two-dimensional Lorentz gas, where the scattering particle can move into the disk interiors, are considered here. Conditions on the soft-disk potentials and disk separations that guarantee chaotic motion are obtained.

Journal Article↗
PubMed1982

Extraneural metastases from cerebellar medulloblastoma.

Six of 19 patients treated for medulloblastoma over an 8-year period developed extraneural metastases. The most common sites of metastatic disease were bone (5 patients), and bone marrow (4 patients). Radionucleotide bone scans and/or bone marrow aspirates detected disease in all such cases. Four patients also had recurrence within the central nervous system. Four of six patients relapsed within one year of initial treatment. All recurrences were treated with radiotherapy and/or chemotherapy with symptomatic improvement. The use of bone scans and bone marrow aspirations in the follow-up of patients with treated medulloblastoma would seem to be indicated.

Adolescent↗
PubMed1981

Pharmacokinetics of vincristine sulfate in children.

A radioimmunoassay was used to measure vincristine sulfate concentrations in the serum of four children with malignancies (ages 5-16 years) following intravenous (IV) bolus injections. The pharmacokinetic data were analyzed by a non-linear least-square regression program NONLIN. A three-compartment open model fitted the raw data better than a two-compartment model in three patients. In the other patient the raw data fitted a two-compartment open model. The half-lives of the triphasic decay curves alpha, beta, and gamma were 2.6, 41, and 1,531 min (25.5 h), respectively. The mean apparent volume of the central compartment was 3.25 l, and the the volume of distribution per 1.73 m2 body surface area at steady state was 215.9 l. In a three-compartment open model, the first-order distribution and elimination rate constants (min-1) of vincristine were as follows: k12, 0.088; k13, 0.121; k21, 0.028; k31, 0.0026; k10, 0.045. The plasma clearance was 146.2 ml/min per 1.73 m2, while the AUC0 infinity was 27,816 nM . min. Urinary excretion in one patient demonstrated a drug concentration of greater than 1.0 X 10(-7) M in the urine up to 78 h after the injection. Up to 37% of the administered drug was excreted in the urine as vincristine and/or its metabolites by 90 h. The low elimination rate constant from poorly perfused tissues to blood plasma (k31), a large apparent volume of distribution, and a long biological half-life (25.5 h) indicate avid tissue binding from which a slow release of the drug from the body tissues occurs.

Adolescent↗
PubMed1980

Favorable response to maintenance therapy of second or subsequent remissions in childhood acute lymphocytic leukemia.

Twenty-two children with acute lymphocytic leukemia (ALL) who had relapsed while on therapy and for whom remissions were successfully reinduced were maintained with a combination of methotrexate, daunomycin, 6-mercaptopurine, prednisone, and vincristine (Djerassi-methotrexate with BOMB). The median duration of remission was 35 weeks (range, five to 364+ weeks). Of 8 children (36%) did not relapse while receiving this therapy, 4 are off all therapy (durations of remissions, 40+, 97+, 132+, and 216+ weeks). Improved responses were found in children with platelet counts of greater than 10(5)/mm3 at the time of index relapse. Intrathecal chemotherapy seemed to greatly prolong the duration of remission for 16 children when compared to those children who did not receive IT therapy (45.5 vs. 24 weeks). No central nervous system relapses occurred. This maintenance regimen for children with previously relapsed ALL appears to be effective and worth additional clinical trials.

Adolescent↗
PubMed1978

Prognosis after metastases in osteosarcoma.

Data from 106 patients with osteosarcoma who developed metastases during treatment were analyzed for prognostic factors for postmetastic survival time. Patients diagnosed in 1971 or later received more intensive chemotherapy and had significantly longer postmetastatic survival time than those diagnosed in 1970 or earlier (P = 0.002). Patients whose metastasis occurred 13 or more months after diagnosis had signicantly longer postmetastatic survival time than those whose metastasis occurred during the first 12 months after diagnosis (P = 0.005). Life-table regression analysis revealed an interaction between "year of diagnosis" and "months to metastasis" which provided a postmetastatic survival advantage for those having metastasis after diagnosis over metastasis at diagnosis for patients diagnosed in 1971 or later but not for those diagnosed in 1970 or earlier (P = 0.093).

Adolescent↗