The hypervolume under the ROC hypersurface of "near-guessing" and "near-perfect" observers in N-class classification tasks

We express the performance of the N-class "guessing" observer in terms of the N2-N conditional probabilities which make up an N-class receiver operating characteristic (ROC) space, in a formulation in which sensitivities are eliminated in constructing the ROC space (equivalent to using false-negative fraction and false-positive fraction in a two-class task). We then show that the "guessing" observer's performance in terms of these conditional probabilities is completely described by a degenerate hypersurface with only N-1 degrees of freedom (as opposed to the N2-N-1 required, in general, to achieve a true hypersurface in such a ROC space). It readily follows that the hypervolume under such a degenerate hypersurface must be zero when N > 2. We then consider a "near-guessing" task; that is, a task in which the N underlying data probability density functions (pdfs) are nearly identical, controlled by N-1 parameters which may vary continuously to zero (at which point the pdfs become identical). With this approach, we show that the hypervolume under the ROC hypersurface of an observer in an N-class classification task tends continuously to zero as the underlying data pdfs converge continuously to identity (a "guessing" task). The hypervolume under the ROC hypersurface of a "perfect" ideal observer (in a task in which the N data pdfs never overlap) is also found to be zero in the ROC space formulation under consideration. This suggests that hypervolume may not be a useful performance metric in N-class classification tasks for N > 2, despite the utility of the area under the ROC curve for two-class tasks.     

Radiotherapy for post-operative inflammatory breast cancer

Two patients with inflammatory breast cancer treated with a combination of radical mastectomy, irradiation, and immunochemotherapy are reported. After radical mastectomy, both patients were given a dose of 4000 rad and 5000 rad to the chest wall and parasternal lymph nodes, and 5000 rad to the axillary and supraclavicular lymph nodes. However, both patients died of recurrence within the irradiated field of the chest wall and metastatic spread to the neighbouring skin. A discussion on the dose and field in radiation therapy for inflammatory breast cancer is presented.     

Road traffic accidents and the Abbreviated Injury Scale (ais) in Japan

Although in Japan the number of casualties from road traffic accidents decreased substantially during a period of improvement of safety measures, in recent years it has remained rather constant. To decrease accidents still further it is necessary to investigate the circumstances of road traffic accidents and the severity of resulting casualties in detail. For this purpose 167,721 cases of road traffic accident casualties occurring between February and April 1979, throughout Japan were analyzed. (1) It was found that 74.2% of all the cases suffered injuries corresponding to AIS-1; 30% of these involved neck injuries. (2) There were 2,654 fatal cases, 67% of which involved head injuries, chiefly cerebral contusion, cranial base fracture, and intracranial hemorrhage. There were fatal cases in the categories of AIS-3 or below which are generally considered not fatal, but those were due to complications. (3) The chief sites of injury varied according to the victim's mode of transport: in an automobile the neck was the site most frequently injured; on a motorcycle the legs and head were usually involved; on a bicycle or walking the head and legs were most at risk. (4) Injuries to pedestrians often fell under the severer AIS-4 or higher codes and constituted 43% of total deaths. (5) Accidents with automobiles changing lanes tended to cause serious injuries and many deaths. Other characteristics of road traffic accidents in Japan are analyzed and discussed.     

Mechanism of enhanced precipitation phenomena in Pb(Sb) alloys with trace element As

The decomposition process of supersaturated solid solution of the Pb-Sb alloys with a small amount of As (∼0.01 wt pct), has been investigated by electrical resistivity measurement. The precipitation process of the Pb-Sb alloys with As is similar to that of the previously reported Pb-As alloys. In the first stage, diffusion of quenched-in excess vacancies accelerates and rate-controls the migration of As and Sb atoms forming an intermediate phase. The second stage is the precipitation of the intermediate phase under the equilibrium vacancy concentration and the third is precipitation of the equilibrium phase. A retardation of reaction in isothermal aging and a partial reversion in isochronal aging appear between the last two stages. The analysis of resistivity change in the Pb-As and Pb-Sb-As alloys shows that the composition and the crystal structure of the intermediate phase are different from those of the equilibrium phase. The mechanism that the preexisted intermediate phase acts as a preferential nucleation site for the equilibrium phase can explain the enhanced precipitation phenomena of the Pb-Sb alloys with trace element As. The reason for the difference in behavior between As and Sb atoms in lead is also discussed.     

Reappraisal of eight representative carcinogenic and non-carcinogenic compounds in a new medium-term rat liver bioassay using D-galactosamine

Tuberculosis incidence and mortality rates are rising steeply, reflecting economic hardship and the deterioration of the health infrastructure. The human and technical resources needed to reverse this trend are on hand, but cannot be used effectively without an adequate financial input. The cost of controlling tuberculosis now is modest compared with the cost of allowing it to increase.     

Expression and ultrastructural localization of HMB-45 antigen

HMB-45 is a monoclonal antibody specific for melanoma cells and premature developing melanocytes. We examined the expression and specific subcellular binding sites of HMB-45 in various types of melanocytes including epidermal melanocytes from fetuses and infants with or without tyrosinase-negative oculocutaneous albinism (type IA), melanin-producing and non-producing melanoma cell lines (G361 and MeWo), and in vivo melanoma cells (melanotic and amelanotic malignant melanoma). Subcellular HMB-45 binding was examined by using post-embedding immunogold electron microscopy with rapid freezing and freeze substitution fixation methods without the use of chemical fixatives to preserve the intracytoplasmic delicate antigen property of HMB-45. HMB-45 antigen was detected not only in in vivo melanoma cells and normal fetal melanocytes, but also in melanocytes in the other conditions. Post-embedding immunogold electron microscopy revealed that HMB-45 antigen was exclusively localized to stages I and II melanosomes in the cytoplasm of neoplastic melanocytes, but was detected mainly on stages II and III melanosomes in the melanocytes from fetuses and infants. In tyrosinase-negative oculocutaneous albinism, only stages I and II melanosomes were detected in the cytoplasm, but both stages of melanosomes were HMB-45 positive. We conclude that HMB-45 appears mainly on the immature melanosomes during melanogenesis in both neoplastic and non-neoplastic melanocytes regardless of their tyrosinase activity, but the intracytoplasmic localization of HMB-45 antigen is different by each condition of melanocytes.     

Selective MR angiography of the liver

OBJECTIVE: Two-dimensional time-of-flight MR angiography was done with a 1.0 T whole-body imaging system. METHODS: The 10 mm thick presaturation slab was positioned between two sagittal imaging slices of the liver. Images were obtained through the right lobe of the liver by moving the slab and slices together. Each image was acquired during a breath-holding interval of 16 s. RESULTS: Since the directions of the portal and hepatic venous flows are opposite to each other in the right lobe, these two venous systems could be visualized on separate images by the interleaved presaturation slab. On the reconstructed angiograms, separation between the two venous systems was complete and even the fourth and fifth branches were demonstrated clearly. These images facilitate clear understanding of the structure of the intrahepatic blood vessels. CONCLUSION: Although this technique is limited to volunteer studies and works only on the right lobe of the liver, it will provide valuable information for evaluating the location and vascular involvement in various liver diseases.