Nano Josephson superconducting tunnel junctions in YBa2Cu3O(7-δ) directly patterned with a focused helium ion beam.

Since the discovery of the high-transition-temperature superconductors (HTSs), researchers have explored many methods to fabricate superconducting tunnel junctions from these materials for basic science purposes and applications. HTS circuits operating at liquid-nitrogen temperatures (∼77 K) would significantly reduce power requirements in comparison with those fabricated from conventional superconductors. The difficulty is that the superconducting coherence length is very short and anisotropic in these materials, typically ∼2 nm in the a-b plane and ∼0.2 nm along the c axis. The electrical properties of Josephson junctions are therefore sensitive to chemical variations and structural defects on atomic length scales. To make multiple uniform HTS junctions, control at the atomic level is required. In this Letter we demonstrate all-HTS Josephson superconducting tunnel junctions created by using a 500-pm-diameter focused beam of helium ions to directly write tunnel barriers into YBa2Cu3O(7-δ) (YBCO) thin films. We demonstrate the ability to control the barrier properties continuously from conducting to insulating by varying the irradiation dose. This technique could provide a reliable and reproducible pathway for scaling up quantum-mechanical circuits operating at liquid-nitrogen temperatures, as well as an avenue to conduct novel planar superconducting tunnelling studies for basic science.

Photoactivation of lysosomally sequestered sunitinib after angiostatic treatment causes vascular occlusion and enhances tumor growth inhibition.

The angiogenesis inhibitor sunitinib is a tyrosine kinase inhibitor that acts mainly on the VEGF and PDGF pathways. We have previously shown that sunitinib is sequestered in the lysosomes of exposed tumor and endothelial cells. This phenomenon is part of the drug-induced resistance observed in the clinic. Here, we demonstrate that when exposed to light, sequestered sunitinib causes immediate destruction of the lysosomes, resulting in the release of sunitinib and cell death. We hypothesized that this photoactivation of sunitinib could be used as a vaso-occlusive vascular-targeting approach to treating cancer. Spectral properties of sunitinib and its lysosomal accumulation were measured in vitro. The human A2780 ovarian carcinoma transplanted onto the chicken chorioallantoic membrane (CAM) and the Colo-26 colorectal carcinoma model in Balb/c mice were used to test the effects of administrating sunitinib and subsequently exposing tumor tissue to light. Tumors were subsequently resected and subject to immunohistochemical analysis. In A2780 ovarian carcinoma tumors, treatment with sunitinib+light resulted in immediate specific angio-occlusion, leading to a necrotic tumor mass 24 h after treatment. Tumor growth was inhibited by 70% as compared with the control group (**P<0.0001). Similar observations were made in the Colo-26 colorectal carcinoma, where light exposure of the sunitinib-treated mice inhibited tumor growth by 50% as compared with the control and by 25% as compared with sunitinib-only-treated tumors (N≥4; P=0.0002). Histology revealed that photoactivation of sunitinib resulted in a change in tumor vessel architecture. The current results suggest that the spectral properties of sunitinib can be exploited for application against certain cancer indications.

The role, responsibilities and status of the clinical medical physicist in AFOMP.

This document is the first of a series of policy statements being issued by the Asia-Oceania Federation of Organizations for Medical Physics (AFOMP). The document was developed by the AFOMP Professional Development Committee (PDC) and was endorsed for official release by AFOMP Council in 2006. The main purpose of the document was to give guidance to AFOMP member organizations on the role and responsibilities of clinical medical physicists. A definition of clinical medical physicist has also been provided. This document discusses the following topics: professional aspects of education and training; responsibilities of the clinical medical physicist; status and organization of the clinical medical physics service and the need for clinical medical physics service.

The role of abdominal angiography in difficult gastrointestinal bleeding.

Two cases of leiomyomas of the jejunum presenting with gastrointestinal bleeding of uncertain origin are described. Diagnosis was finally established by selective angiography. Laparotomy and resection of the tumour were successfully performed. The approach and management of this rare tumour are outlined.

Computers in radiotherapy.

Radiotherapy is one of the earliest fields in Medicine in which computers have made an inroad. The main uses of computers, which include treatment planning, dose calculations, localisation of tumours, verification of patient setups and radiation beam data acquisition, are highlighted in this paper. It is believed that a modern Radiotherapy department cannot function optimally without some form of computing facilities. With advances made in dose calculation algorithms, and in high performance computers, it is expected that the target of 3% accuracy dose calculations can be achieved in treatment planning.

Management of xiphopagus conjoined twins with small bowel obstruction.

A set of xiphopagus conjoined twins with prematurity, exomphalos, and intestinal obstruction was separated successfully. Preoperative evaluation included computerised axial tomography, 99mTc-HIDA scan, and barium enema. Major hepatobiliary and gastrointestinal anomalies were encountered. One twin is alive and well today. The other twin died one week postoperatively from sepsis. Postmortem studies showed she had a severe cardiac anomaly incompatible with normal life.

Choledochal cyst--a review of 25 cases.

Twenty-five cases of choledochal cysts operated at the University Hospital between 1969 and 1981 were reviewed. Nineteen of the patients were females. An accurate pre-operative diagnosis of choledochal cyst was made in 10 patients (40%). We have found the 99Tcm-diethyl-IDA (EHIDA) scan to be the safest and most sensitive diagnostic tool. In recent years excision has been performed whenever possible in view of reports of malignancy developing in the cyst wall. It has a lower morbidity and re-operation rate compared to internal drainage. In excision we advise the use of a cuff of the cyst wall for a wider anastomosis. As the biliary tract shrinks and retracts into the porta following excision of the cyst, stricture formation may still occur despite a wide anastomosis.