Eikonal Distorted-Wave Calculation for the Excitation of H by He

The eikonal distorted-wave Born approximation developed recently by Chen, Joachain, and Watson is applied to hydrogen excitation by helium impact in the intermediate-energy range. The differential and total cross sections for the excitation of the hydrogen atom to the 2s, 2p±, or 2p0 state by helium impact are presented. These results are compared to experiment and previous calculations. The differential cross section for the excitation of hydrogen to the 2s state compares well with the experimental data of Thomas and Sauers in shape and slope, but has a discrepancy in magnitude

Eikonal Approximation Applied to Atom-Atom Excitation at Intermediate Energies: Excitation of H by H

The eikonal distorted-wave Born approximation (DWBA) developed recently by Chen, Joachain, and Watson is applied to atom-atom excitation in the intermediate energy range. In this paper the excitation of a hydrogen atom to the 2s, 2p±, or 2p0 state by hydrogen impact is considered. Differential cross sections are presented. Total cross sections are presented and compared to previous calculations. It is shown that the eikonal DWBA results for the total cross section approach the two-state distortion-approximation results in the limit of high energy and very-small-angle scattering

Transcript for Episode 21: Mixed Bag: Constitutional Empowerment of Montana\u27s Local Government

https://digitalcommons.mtech.edu/crucible_transcriptions/1020/thumbnail.jp

Postenucleation adjuvant chemotherapy with vincristine, etoposide, and carboplatin for the treatment of high-risk retinoblastoma.

BACKGROUND: Analysis of 52 eyes with high-risk retinoblastoma managed with postenucleation adjuvant chemotherapy using vincristine sulfate, etoposide phosphate, and carboplatin showed no evidence of systemic metastasis in any case during a mean (range) follow-up of 66 (12-202) months. PURPOSE: To determine the efficacy of postenucleation adjuvant chemotherapy with vincristine, etoposide, and carboplatin in the prevention of metastasis for patients with high-risk retinoblastoma. METHODS: Retrospective, nonrandomized, interventional case series of 52 eyes in 51 patients with high-risk retinoblastoma consisting of tumor invasion into the anterior segment, posterior uvea 3 mm or greater, postlaminar optic nerve, or any combination of posterior uvea and optic nerve involvement. RESULTS: Of 51 consecutive patients with high-risk retinoblastoma, there were 30 males (59%) and 21 females (41%), with a median age of 28 months at diagnosis. All 52 eyes were classified as group E. The main histopathologic risk factors included anterior segment invasion (7 [13%]), isolated massive posterior uveal invasion of 3 mm or greater (6 [12%]), isolated postlaminar optic nerve invasion (15 [29%]), or any posterior uveal invasion with any optic nerve involvement (24 [46%]). There was additional invasion into the sclera (3 [6%]) and extrascleral structures, including the orbit (1 [2%]). A single histopathologic high-risk factor was present in 32 eyes (62%), whereas 20 eyes (38%) manifested 2 or more high-risk characteristics. Based on previously published series, untreated high-risk retinoblastoma carries at least a 24% risk for metastatic disease. In the present series, using vincristine, etoposide, and carboplatin in all cases, there was no metastasis during a mean follow-up of 66 months (median [range], 55 [12-202] months). CONCLUSIONS: Retinoblastoma with invasion into the postlaminar optic nerve and/or posterior uvea is at high risk for metastasis and death. In this study, postenucleation chemotherapy using vincristine, etoposide, and carboplatin was effective in preventing metastasis in every case (100%)

Conjunctival Melanoma: Features Based on the Fitzpatrick Skin Type (FST) in 540 Patients at a Single Ocular Oncology Center

Background: The Fitzpatrick skin type (FST) is a classification system for skin pigmentation that has been used to stratify risk for cutaneous melanoma; however, it has not yet been explored in the context of conjunctival melanoma. Herein, we examine FST and its association with the clinical features of conjunctival melanoma. Methods: A retrospective review was conducted on 540 medical records of patients with pathologic diagnosis of conjunctival melanoma. The patients were categorized according to the FST classification based on their external facial photographs at presentation. This includes: Type I (white skin color), Type II (fair skin color), Type III (average skin color), Type IV (light-brown skin color), Type V (brown skin color), and Type VI (black skin color). Other clinical features (namely tumor characteristics, tumor location, and tumor color) were also noted. Results: The FST included Types I (n=126, 23%), II (n=337, 62%), III (n=56, 10%), IV (n=8, 2%), V (n=12, 2%), and VI (n=1, \u3c1%). Statistical analysis (FST I vs. FST II vs. FST III, IV, V, and VI) revealed FST I and II tumors had smaller tumor thickness (2.1 vs. 2.8 vs. 3.6 mm, p=0.01) and less eyelid involvement (13% vs. 13% vs. 28%, p=0.02). Discussion: In this analysis, we found that the majority of patients with conjunctival melanoma are FST I or II; they also had smaller tumor thickness and less eyelid involvement than FST III, IV, V, and VI. Thus, patients with FST I and II should be considered a phenotype at risk for conjunctival melanoma and be observed accordingly

Melanoma of the Choroid in a Dog

Intraocular tumors are rare in the dog. Of the reported neoplasms, melanomas are the most common. These tumors characteristically arise in the anterior uvea and secondarily infiltrate posteriorly into the choroid and/or anteriorly into the corneoscleral region. Advanced tumors may extend extraocularly. In the dog, isolated choroidal melanomas are extremely uncommon; to the authors\u27 knowledge, only two cases have been previously reported. This report describes a pigmented choroidal tumor in a dog with clinical and histopathologic features resembling a benign melanoma

Photodynamic Therapy in Ocular Oncology

Over the past two decades, we have witnessed the increasing use of photodynamic therapy (PDT) in the field of ocular oncology. Based on a review of the literature and our own experience, we herein review the role of PDT for the management of intraocular tumors. The discussion includes two main topics. First, we discuss the application of PDT for benign tumors, including circumscribed choroidal hemangioma, choroidal osteoma, retinal astrocytoma, retinal capillary hemangioma (retinal hemangioblastoma), and retinal vasoproliferative tumor. Second, we assess the role of PDT for malignant tumors, including choroidal melanoma and choroidal metastasis

Effects of capecitabine treatment on the uptake of thymidine analogs using exploratory PET imaging agents: 18F-FAU, 18F-FMAU, and 18F-FLT

Patient Image Data. (XLSX 19 kb