Two-Component Scaling near the Metal-Insulator Bifurcation in Two-Dimensions

We consider a two-component scaling picture for the resistivity of two-dimensional (2D) weakly disordered interacting electron systems at low temperature with the aim of describing both the vicinity of the bifurcation and the low resistance metallic regime in the same framework. We contrast the essential features of one-component and two-component scaling theories. We discuss why the conventional lowest order renormalization group equations do not show a bifurcation in 2D, and a semi-empirical extension is proposed which does lead to bifurcation. Parameters, including the product $z\nu$, are determined by least squares fitting to experimental data. An excellent description is obtained for the temperature and density dependence of the resistance of silicon close to the separatrix. Implications of this two-component scaling picture for a quantum critical point are discussed.Comment: 7 pages, 1 figur

Orchidectomy after chemotherapy for patients with metastatic testicular germ cell cancer

Objective: to evaluate the contribution of routine orchidectomy in the management of patients who present with advanced, metastatic, testicular germ cell cancer and who are treated with initial chemotherapy.Patients and methods: sixty consecutive patients presenting with metastatic testicular germ cell cancer and treated with initial chemotherapy followed by orchidectomy were identified. The results from a clinical and pathological review of these patients are presented. The pathological findings at orchidectomy were compared with the pathological findings from metastatic masses resected after chemotherapy, and are reviewed with the clinical outcome.Results: of the 60 orchidectomy specimens after chemotherapy, 24 (40%) contained significant histological abnormalities comprising residual invasive germ cell cancer, intratubular germ cell neoplasia and/or mature teratoma. The remaining 36 (60%) orchidectomy specimens contained fibrous scarring with or with no necrosis. Six (10%) orchidectomy specimens contained residual invasive germ cell cancer, three nonseminomatous germ cell cancer (NSGCT) and three seminoma. The patients with residual invasive NSGCT present within the testis had evidence of residual invasive NSGCT within extragonadal masses resected after chemotherapy; all three have relapsed and died from chemorefractory progressive disease.Conclusion: orchidectomy after chemotherapy is recommended in all patients undergoing primary chemotherapy, as a significant proportion (40%) are left with histological abnormalities that predispose to subsequent relapse. Persistence of invasive NSGCT at the site of the primary tumour after chemotherapy is associated with persistence of invasive disease at other metastatic sites and is a poor prognostic finding

An unusual differential diagnosis of penile warts: metastases from rectal carcinoma

Patients with penile lesions, such as virally induced papillomata, frequently present to genitourinary medicine clinics and general practitioners. Their diagnosis is usually based on clinical observation and biopsy is not generally undertaken. Penile lesions may rarely have a more sinister aetiology and represent metastatic spread from solid tumours arising at distant sites. Penile metastases arise most frequently from genitourinary cancers (prostate, bladder and kidney), but may also arise from tumours of the large bowel; other primary sites are extremely uncommon. We report the case of a patient presenting with penile metastases from rectal carcinoma arising during third-line chemotherapy for metastatic diseas

Late relapse of metastatic non-seminomatous testicular germ cell tumours

Although the majority of men presenting with non-seminomatous germ cell tumours (NSGCT) are cured, late relapse (occurring more than 2 years after obtaining a complete response to treatment) is increasingly recognized. The typical patterns of disease spread have been well-documented, but the findings at late relapse are more variable and less well-described. We discuss the phenomenon of late relapse, the characteristics of teratoma differentiated (TD), and the issue of long-term imaging surveillance of patients with NSGCT. The potential sites of late relapse of NSGCT and the associated spectrum of imaging appearances are illustrated