Gulf Stream Ring Coalescence with the Gulf Stream off Cape Hatteras.

A cyclonic ring, which had separated from the Gulf Stream 7 months earlier and traveled 500 kilometers westward, collided with the stream in September 1977. Within 3 days the ring and stream joined to form a sharp S-shaped meander. Shipboard expendable temperature probes and four bottom-moored inverted echo sounders were used to obtain synoptic descriptions of the rejoining process.

Connectivity of marine populations: open or closed?

Most marine populations are thought to be well connected via long-distance dispersal of larval stages. Eulerian and Lagrangian flow models, coupled with linear mortality estimates, were used to examine this assumption. The findings show that when simple advection models are used, larval exchange rates may be overestimated; such simplistic models fail to account for a decrease of up to nine orders of magnitude in larval concentrations resulting from diffusion and mortality. The alternative process of larval retention near local populations is shown to exist and may be of great importance in the maintenance of marine population structure and management of coastal marine resources.

A magnetic bearing system for a continuous ventricular assist device.

This article describes a prototype continuous flow ventricular assist device (CFVAD3) supported in magnetic bearings. The VAD is a small centrifugal four bladed pump. The pump's geometry is explained. The CFVAD3 is the first compact VAD completely supported in magnetic bearings. The magnetic bearings are composed of an inlet side actuator divided into eight pole sets, and an outlet side actuator, also divided into eight pole sets. The pump operating performance was tested and found to be within the design flow rate of up to 9 L/min, and head up to 170 mm Hg for human circulatory support. Magnetic bearing operation out of center positions under various operating orientations were measured and found to be < 1/6 of the bearing clearance, well within specifications. The expected magnetic bearing power loss has been calculated at approximately 6.5 watts.

Effects of spatial grouping on the functional response of predators.

A unified mechanistic approach is given for the derivation of various forms of functional response in predator-prey models. The derivation is based on the principle of mass action but with the crucial refinement that the nature of the spatial distribution of predators and/or opportunities for predation are taken into account in an implicit way. If the predators are assumed to have a homogeneous spatial distribution, then the derived functional response is prey-dependent. If the predators are assumed to form a dense colony or school in a single (possibly moving) location, or if the region where predators can encounter prey is assumed to be of limited size, then the functional response depends on both predator and prey densities in a manner that reflects feeding interference between predators. Depending on the specific assumptions, the resulting functional response may be of Beddington-DeAngelis type, of Hassell-Varley type, or ratio-dependent.

Myelodysplastic syndromes. A clinical and pathologic analysis of 109 cases.

A total of 109 patients with myelodysplastic syndromes (MDS) was analyzed to determine the clinical and pathologic features of the five recently defined French-American-British Cooperative Group (FAB) subtypes, and to assess the utility of this classification system in predicting survival, evolution to acute nonlymphocytic leukemia (ANLL), and cause of death. All patients with MDS presented with anemia; additional cytopenias were present in patients with refractory anemia with excess blasts (RAEB), chronic myelomonocytic leukemia (CMML) and refractory anemia with excess blasts in transformation to ANLL (RAEB/Tr). Thirty-two patients received some form of antileukemic therapy for MDS. ANLL developed in 16 of the 77 remaining untreated patients, including 18% (2/11), 0% (0/21), 22% (5/23), 33% (2/6), and 44% (7/16) of patients with refractory anemia (RA), refractory anemia with ring sideroblasts (RARS), RAEB, CMML, and RAEB/Tr, respectively (P = 0.02). The FAB subtype was highly predictive of survival with median survivals ranging from 71 months for RARS to 5 months for RAEB/Tr (P = less than 0.0001). Patients with RAEB, CMML, and RAEB/Tr frequently died of direct consequences of MDS, while patients with RA and especially RARS generally survived or died from unrelated disorders (P = less than 0.0001). MDS encompass a spectrum of disorders. RA and RARS, are relatively indolent and often do not lead to the patient's demise. RAEB, CMML, and RAEB/Tr are aggressive disorders which are often responsible for the patient's death whether or not actual progression to overt leukemia occurs. FAB subtype predicts survival, evolution to ANLL, and cause of death, although the five morphologic subtypes appear to separate into only two disease groups, especially with regard to survival and cause of death.

Drinking water and cancer incidence in Iowa. III. Association of cancer with indices of contamination.

With data from the Iowa Cancer Registry, age-adjusted sex-specific cancer incidence rates for the years 1969-1981 were determined for towns with a population of 1,000-10,000 and a public water supply from a single stable ground source. These rates were related to levels of volatile organic compounds and metals found in the finished drinking water of these towns in the spring of 1979. Results showed association between 1,2 dichloroethane and cancers of the colon and rectum and between nickel and cancers of the bladder and lung. The effects were most clearly seen in males. These associations were independent of other water quality and treatment variables and were not explained by occupational or other sociodemographic features including smoking. Because of the low levels of the metals and organics, the authors suggest that they are not causal factors, but rather indicators of possible anthropogenic contamination of other types. The data suggest that water quality variables other than chlorination and trihalomethanes deserve further consideration as to their role in the development of human cancer.

Respiratory illnesses in survivors of infant respiratory distress syndrome.

This prospective study examined the frequency and severity of respiratory illnesses in survivors of preterm birth compared with those in full-term infants. Although preterm infants did not demonstrate an inherent risk of subsequent respiratory illness when compared with full-term infants, earlier and more severe lower respiratory illnesses were observed among survivors of idiopathic respiratory distress syndrome (RDS). Infants who survived RDS but who developed residual lung disease had a greater risk of both more frequent and more severe subsequent lower respiratory illnesses than did RDS survivors who did not have persistent roentgenographic changes. We suggest that the risk of increased respiratory illness in these infants was a consequence of residual pulmonary abnormalities apparent on the chest roentgenogram at discharge from the nursery. Agents associated with respiratory illnesses were similar in all groups of study patients.

Is microstaging of early invasive cancer of the urinary bladder possible or useful?

Reports suggest that it is possible and useful to classify T1 (Stage A) carcinomas of the urinary bladder into subgroups dependent on the depth of invasion as defined by the muscularis mucosae (MM). In an attempt to evaluate the reproducibility of these findings, we reviewed the slides from 77 cases of T1 bladder cancer diagnosed in 1983 in Iowa residents. The cases were identified through a statewide cancer registry. Slides and pathology reports were obtained from the original laboratories. Two pathologists independently evaluated each case, most (74 cases) of which were transurethral resections, for the presence or absence of MM and three levels of invasion (lamina propria, MM, and submucosa). Disagreements were resolved by simultaneous review resulting in a consensus diagnosis. Because of the population-based source, tissue had been obtained by multiple urologists and processed in multiple laboratories, resulting in noticeable variation in quality of material. Interobserver agreement for the level of invasion was poor between the two pathologists (kappa = 0.22; 95% C.I. = 0.08-0.36). Consensus resulted in 34 cases (44.2%) invasive to the lamina propria, 23 (29.9%) to the MM, and 11 (14.3%) to the submucosa. The level was indeterminate in nine (11.7%). All of the 77 cases were followed until death or 1993-95, with 57 patients dying during this interval. There were no significant differences in survival for each level of invasion (lamina propria, MM, submucosa) and the indeterminate cases, as determined by either consensus or individual observer evaluation. Our findings suggest that microstaging of early invasive bladder cancer is technically difficult and, at least in cases derived from various urologists and laboratories, does not yield a prognostically significant separation.