Anthropologists have long been interested in the cultures and customs of the aboriginal inhabitants of North America, and investigators have long sought to determine the type of society utilized by the American Indian, concentrating mainly on their origin and degree of civilization. The development of modem ecology, however, spawned new areas of interest and both anthropologists and biologists became aware of the fact that American Indian culture involved not only a type of civilization, but an intimate relationship with and an unsurpassed knowledge of the land on which he lived. This ability to coexist with nature was never 50 evident as it has become within the past fifteen years, as a result of the deteriorating environment modern society has produced. Society has finally realized the preciousness of natural habitats and begun to develop a "back-to-nature" attitude with emphasis on the preservation of our natural resources. This new attitude has brought with it the realization that, before the coming of the white man, the American Indian had learned to live in harmony with nature and actually shaped the forests and prairies to his own benefits with little detrimental effect on the land. How he was able to do this has been a subject of controversy for many years and a subject that modern ecologists have found difficult to digest. Today there is little doubt that the Indians were able to maintain their environment through the use of fire. Evidence is presented in the from of prescribed burning now being instituted in most U.S. parks and forests. The following discussion is a brief survey of the use of fire by American Indians as fire ecologists, and the ultimate decision to return to tradition.

Direct volume rendering based on projective methods works by projecting, in visibility order, the polyhedral cells of a mesh onto the image plane, and incrementally compositing the cell's color and opacity into the final image. Crucial to this method is the computation of a visibility ordering of the cells. If the mesh is ''well-behaved'' (acyclic and convex), then the MPVO method of Williams provides a very fast sorting algorithm; however, this method only computes an approximate ordering in general datasets, resulting in visual artifacts when rendered. A recent method of Silva et al. removed the assumption that the mesh was convex, by means of a sweep algorithm used in conjunction with the MPVO method; their algorithm is substantially faster than previous methods for general meshes. In this paper we propose a new technique, which we call BSP-XMPVO, which is based on a fast and simple way of using binary space partitions on the boundary elements of the mesh to augment the ordering produced by MPVO. Our results are shown to be orders of magnitude better than previous methods of sorting cells

Purpose

Obesity has increased dramatically in American society during the last 2 decades. While the laparoscopic approach is common for patients requiring radical and partial nephrectomy, it is unclear if this procedure leads to worse outcomes and complications in obese patients. We determined if obese patients undergoing laparoscopic radical (RN), partial (PN) and simple (SN) nephrectomy are at risk for worse surgical outcomes or increased complications.

Materials and methods

We retrospectively identified patients treated with nontransplant transperitoneal laparoscopic nephrectomies from 1998 to 2003. Patients with missing body mass index (BMI), operative, postoperative or pathological information were excluded from study. Obese patients (BMI 30 or greater) were compared to nonobese patients (BMI less than 30).

Results

A total of 189 patients undergoing 117 RN, 44 PN and 30 SNs met study criteria, and 29.0% of patients were obese. Overall obese patients had longer operative times (280 versus 241 minutes, p = 0.003), greater estimated surgical blood loss (230 versus 109 ml, p = 0.0001) and higher transfusion rates (6.8% versus 0.8%, p = 0.032) than nonobese patients. In subgroup analyses obese patients receiving RN and PN had longer operative times and increased blood loss. Obese and nonobese patients have similar open conversion rates, analgesic requirements, hospital stay, time to oral intake, and major and minor complication rates regardless of nephrectomy type.

Conclusions

Laparoscopic nephrectomy is associated with slightly greater operative time, estimated blood loss and transfusion rates in obese patients. Laparoscopic RN, PN and SN are safe and well tolerated in obese patients. Obesity is not a contraindication to laparoscopic renal surgery.

Purpose

Two methods widely used to predict the risk of treatment failure after radical prostatectomy for localized prostate cancer are the 3 level D'Amico risk classification and the Kattan nomogram. Although they have been previously validated, to our knowledge they have not been compared in a community based cohort. We tested the 2 instruments in the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) database, a national registry of patients with prostate cancer, to assess their accuracy in a community based cohort.

Materials and methods

Men were invited to join CaPSURE from 33 American urology practices, of which 30 were community based. A total of 1,701 men with localized prostate cancer (T1-3a) were treated with radical prostatectomy between 1989 and 2000. Patients who received neoadjuvant or adjuvant therapy were excluded. Recurrence was defined as 2 or more consecutive prostate specific antigen measurements of 0.2 ng/ml or greater, or a second treatment greater than 6 months after surgery. Freedom from progression (FFP) was based on life table estimates and Kaplan-Meier curves. Risk groups were compared using a Cox proportional hazards model and ANOVA.

Results

Based on the D'Amico classification 671 cases (39%) were classified as low risk, 446 (26%) were intermediate risk and 584 (34%) were high risk. Five-year FFP was 78%, 63% and 60% in the low, intermediate and high risk groups (HR 1.00, 1.87 and 2.32 respectively, p <0.0001). Mean 5-year FFP predicted by the Kattan nomogram in the same risk groups was 91%, 74% and 69%, respectively. Outcomes in the low risk group were tightly grouped about the mean but there was considerable dispersion of outcomes in the intermediate (30% to 98% FFP) and high (17% to 98%) risk groups.

Conclusions

Stratifying patients in CaPSURE into low, intermediate and high risk categories for disease as described by D'Amico or applying the Kattan nomogram resulted in statistically significant differences in predicted 5-year FFP. However, there was considerable overlap of outcomes between the intermediate and high risk groups. This analysis suggests that simply estimating disease recurrence by stratifying patients into low, intermediate and high risk groups may not provide sufficient information for predicting outcomes among individuals.