Gastropods are an important component of subtidal Antarctic communities including in common association with macroalgae. Nonetheless, limited data exist detailing their abundance and distribution on macroalgal species. This study documents the abundance and species composition of gastropod assemblages on the two largest, blade-forming Antarctic macroalgae, Himantothallus grandifolius and Sarcopeltis antarctica, sampled across two depths (9 and 18 m) at four sites for each species off Anvers Island, Antarctica. Gastropods were also enumerated on Desmarestia anceps, Desmarestia antarctica and Plocamium sp. but were not included in the main analyses because of small sample sizes. There were major differences between the gastropod assemblages on deep vs shallow H. grandifolius and S. antarctica with much higher numbers of individuals and also greater numbers of gastropod species at the greater depth. Differences between the gastropod assemblages on H. grandifolius and S. antarctica across sampling sites were apparent in non-parametric, multivariate analyses, although depth contributed more than site to these differences. Within common sites, assemblages on H. grandifolius were significantly different from those on S. antarctica at 18 m depth but not at 9 m depth, indicating that the host species can be but is not always more important than site in influencing the gastropod assemblages.

One major challenge in the study of late-Quaternary extinctions (LQEs) is providing better estimates of past megafauna abundance. To show how megaherbivore population size varied before and after the last extinctions in interior Alaska, we use both a database of radiocarbon-dated bone remains (spanning 25–0 ka) and spores of the obligate dung fungus, Sporormiella, recovered from radiocarbon-dated lake-sediment cores (spanning 17–0 ka). Bone fossils show that the last stage of LQEs in the region occurred at about 13 ka ago, but the number of megaherbivore bones remains high into the Holocene. Sporormiella abundance also remains high into the Holocene and does not decrease with major vegetation changes recorded by arboreal pollen percentages. At two sites, the interpretation of Sporormiella was enhanced by additional dung fungal spore types (e.g., Sordaria). In contrast to many sites where the last stage of LQEs is marked by a sharp decline in Sporormiella abundance, in interior Alaska our results indicate the continuance of megaherbivore abundance, albeit with a major taxonomic turnover (including Mammuthus and Equus extinction) from predominantly grazing to browsing dietary guilds. This new and robust evidence implies that regional LQEs were not systematically associated with crashes of overall megaherbivore abundance.

Geophysical granular flows, such as avalanches, debris flows, lahars and pyroclastic flows, are always strongly influenced by the basal topography that they flow over. In particular, localised bumps or obstacles can generate rapid changes in the flow thickness and velocity, or shock waves, which dissipate significant amounts of energy. Understanding how a granular material is affected by the underlying topography is therefore crucial for hazard mitigation purposes, for example to improve the design of deflecting or catching dams for snow avalanches. Moreover, the interactions with solid boundaries can also have important applications in industrial processes. In this paper, small-scale experiments are performed to investigate the flow of a granular avalanche over a two-dimensional smooth symmetrical bump. The experiments show that, depending on the initial conditions, two different steady-state regimes can be observed: either the formation of a detached jet downstream of the bump, or a shock upstream of it. The transition between the two cases can be controlled by adding varying amounts of erodible particles in front of the obstacle. A depth-averaged terrain-following avalanche theory that is formulated in curvilinear coordinates is used to model the system. The results show good agreement with the experiments for both regimes. For the case of a shock, time-dependent numerical simulations of the full system show the evolution to the equilibrium state, as well as the deposition of particles upstream of the bump when the inflow ceases. The terrain-following theory is compared to a standard depth-averaged avalanche model in an aligned Cartesian coordinate system. For this very sensitive problem, it is shown that the steady-shock regime is captured significantly better by the terrain-following avalanche model, and that the standard theory is unable to predict the take-off point of the jet. To retain the practical simplicity of using Cartesian coordinates, but have the improved predictive power of the terrain-following model, a coordinate mapping is used to transform the terrain-following equations from curvilinear to Cartesian coordinates. The terrain-following model, in Cartesian coordinates, makes identical predictions to the original curvilinear formulation, but is much simpler to implement.

Annual rings are not commonly produced in tropical trees because they grow in a relatively aseasonal environment. However, in the subalpine zones of Hawaiʻi's highest volcanoes, there is often strong seasonal variability in temperature and rainfall. Using classical dendrochronological methods, annual growth rings were shown to occur in Sophora chrysophylla, a native tree species on Maunakea, Hawaiʻi. Chronologies were established from nearby non-native, live conifer trees and these were used to verify the dates from a total of 52 series from 22 S. chrysophylla trees, establishing an 86-y chronology (1926–2011). Ring-width patterns were significantly correlated with monthly rainfall from August of the previous year. This study is the first in the eastern tropical Pacific region to demonstrate annual growth rings in trees.

In this review, we discuss and describe those features which distinguish hearts with abnormal atrioventricular septation from the normal heart. The hearts, best described as atrioventricular septal defects, are unified by having a common atrioventricular junction guarded by a valve having five leaflets. The left component has three leaflets and cannot be interpreted in terms of a cleft in a normal mitral valve. The papillary muscles supporting this valve are also markedly dissimilar from the arrangement seen in normal hearts. The subaortic outflow tract is displaced superiorly compared to the normal heart, and is no longer wedged between the left valve and the septum. There is marked discrepancy in the inlet and outlet lengths of the ventricular mass, these dimensions being equal in hearts with normal atrioventricular septation. Although having the above features in common, atrioventricular septal defects show anatomic variations related to the arrangement of the bridging leaflets and their relationship to the septal structures. There may be a common valvar orifice or separate right and left orifices. The anatomic potential for shunting may be at atrial or ventricular levels, or both. Rarely, the septal structures may be intact. Other important features include ventricular dominance, the left ventricular outflow tract, and the disposition of the atrioventricular conduction tissues.

Between January 1985 and March 1990, 66 children with the tetralogy of Fallot underwent 85 cardiac catheterization procedures. The mean age at first procedure was 2.5 years (range 0.1–;14.4 years) and the mean weight was 10.4 kg ( range 2.4–36.0 kg). Diagnostic cardiac catheterization was performed in 60 procedures and balloon dilatation in 25. Hypercyanotic spells had occurred prior to 24 (28%) of the procedures (all the patients being on propranolol) and a systemic-to-pulmonary arterial shunt had been constructed before 28 (33%) procedures. Of the procedures, 54 (64%) were performed under local and 31(36%) under general anesthesia. The pulmonary trunk was entered antegradely in 52 procedures, retrogradely through a shunt in 6 and not entered in 27. Balloon dilatation was performed under general anesthesia on 25 occasions. No procedure was abandoned because of a cyanotic spell. Nine (11%) spells occurred during 86 procedures, one of the procedures being postponed because ofa spell occurring after premedication, the procedure and not, therefore, continuing to catheterization. Five spells occurred before the catheter was positioned in the heart, 2 spells occurred during catheterization. Of the spells, eight occurred during procedures in children who had not had previous shunts. Antegrade entry into the pulmonary trunk in the group with shunts was associated with no spells compared with 6/38 (18%) in the group not having undergone surgery (p<0.l). In the group not undergoing surgery, when the pulmonary trunk was not entered, 1 (5%) spell occurred during 19 procedures compared with 6/38 (18%) when the pulmonary trunk was entered (p<0.4). The only clinically important factor which significantly influenced the incidence of spells was the use of general anesthesia, which was associated with 6/31 (19%) spells compared with local anesthesia which was associated with 2/54 (4%) spells (p<0.026).

Between December 1982 and April 1991, balloon atrial septostomy was performed in the intensive care unit under echocardiographic control in 60 neonates. Of the patients, 58 had complete transposition. Two patients had double outlet right ventricle with a sub-pulmonary ventricular septal defect. Associated lesions included a patent arterial duct in 19 patients, ventricular septal defect in nine, obstruction of the left ventricular outflow tract in six, aortic coarctation in two and tricuspid atresia in one. The mean age at septostomy was four days (range 4 hours - 25 days) and the mean weight 3.19 kg (range 1.17–4.25 kg). In 39 (65%) patients, an infusion of prostaglandin was in progress prior to the septostomy and 22 (37%) were being ventilated. Standard subcostal four-chamber echocardiographic views were used to show the atrial septum and to guide the catheter used for septostomy. Venous access was obtained via the femoral vein in 43 (by percutaneous puncture in 40 and by cutdown in three) and the umbilical vein in 17. Transient atrial arrhythmias were common during the septostomy but no acute hemodynamic disturbances or deaths occurred during the procedure. The size of the atrial septal defect as measured by echocardiography after the septostomy ranged from three to 12 mm in diameter. In only one patient was this inadequate. Three (5%) patients died between two and 10 days after the septostomy, two due to necrotizing enterocolitis and one from persistent hypoxemia. One patient had a cerebral thrombosis and convulsions immediately after the septostomy but made a good neurological recovery. Corrective surgery was performed in 52 (86.6%), two (3.3%) had palliative surgery and two were considered unsuitable for total correction, of whom one has died. One patient died whilst awaiting correction. We conclude that balloon atrial septostomy using echocardiographic guidance can be safely and effectively performed in the intensive care unit.

Twenty-six patients requiring palliation for the tetralogy of Fallot were treated by balloon dilation. The mean age at dilation was 8.5 months (range 0.5−20.6) and the mean weight 6.7 kg (range 2.6−10.7). Successful dilation was achieved in 25 patients. The mean ratio of the balloon to the diameter of the pulmonary outflow tract was 1.6 (range 1.2−2.0). The aortic oxygen saturation increased from mean±SD of 80±12.4% before to 91±4.3% after dilation (p<0.05). The pulmonary arterial oxygen saturation rose from 64±10.7% to 80±7.7% (p<0.05). Transient hypotension and arterial desaturation were noted in 19 patients during inflation of the balloon. One patient had a cardiac arrest prior to dilation and died afterwards. Seven patients had cyanotic spells related to the procedure. Attempts to cross the pulmonary valve resulted in infundibular perforation by the guide wire in one patient. Of the 24 survivors who initially had successful dilation procedures, three have needed a Blalock-Taussig shunt. Palliation without a shunt was achieved in the remaining 21 patients. In 12 patients, repeat angiography, 2.5−20 months (mean 9.1) after dilation, showed an increase in the diameter of the outflow tract from 7.1±2.1 mm before to 9.5±2.0 mm after dilation (p<0.05). Diameters of the pulmonary arteries increased from 6.3±2.2 mm on the right and 6.8±1.9 mm on the left before to 9.2±2.2 mm and 9.3±2.5 mm respectively after dilation (p<0.05 for both branches). Surgical correction has been achieved in 22 patients, 21 of these 2−22 months after balloon dilation and the other patient 20 months after construction of a shunt. At operation, the leaflets of the pulmonary valve were noted to be torn in five patients. In 12 patients, there was extensive scarring of the infundibulum. Balloon dilation of the right ventricular outflow tract achieves adequate palliation and may result in an increase in the diameter of the pulmonary valve and branches of the pulmonary trunk. It should be considered as an alternative to shunt procedures in children with tetralogy of Fallot.

Clinical and Doppler echocardiography were performed in 65 patients who had undergone ligation of the arterial duct between January 1978 and December 1991. Of the patients, 12 (18%) patients had residual patency as demonstrated by color Doppler, while three (4.6%) of these had continuous murmurs. There was no association between residual patency and the age at surgery, the weight at surgery or the follow-up interval.

Formation of aortic aneurysms is an important and not infrequent sequel of surgical repair of aortic coarctation. Detection is often haphazard and fatal ruptures are reported. We report a series of cases where resonance imaging identified aneurysmal dilatation of the thoracic aorta after either patch aortoplasry or subclavian flap repair of aortic coarctation. In one, rupture of the aneurysm occurred five months following the initial resonance study. Repeat imaging confirmed the clinical suspicion of rupture and successful surgical resection was subsequently performed. Magnetic resonance is a practical and reproducible imaging technique which is particularly valuable in the identification of abnormalities within the thoracic aorta following surgical aortoplasty or interventional procedures for aortic coarctation. As a method of routine surveillance in these groups of patients, it is superior to any alternative technique.

In neonates with duct-dependent congenital heart defects, a reliable non-pharmacological, non-surgical method of maintaining flow through the arterial duct may simplify the management. Stent implantation into the arterial duct has been proposed as such a method. In order to evaluate the technical difficulties which may accompany clinical application, stent implantation into the arterial duct was attempted in 32 newborn lambs aged two to nine days (mean 4.2±1.4) weighing 2.4–7.3 kg (mean 4.6±1.0). Four different types of stent were implanted and the ease of implantation and outcomes were assessed. Stent implantation was technically successful in 28 of the 32 lambs (88%). Of these, 11 lambs died shortly after stent implantation with patent ducts, five lambs had early occlusion of the duct and 12 lambs were entered into a long-term study. The Gianturco-Roubin stent was too rigid and too long to enable successful implantation. The Palmaz-Schatz stent was poorly radio-opaque and was difficult to place accurately. When the aortic orifice was not completely covered, the duct occluded within a few days of implantation. The articulation gap also allowed duct tissue to prolapse into the middle of the stent. The Medinvent and Tower stents were simpler to position due to their superior radio-opacity. The Tower stent had an additional advantage in being a single strand stent which could be easily retrieved if misplaced.

We describe a new method of three-dimensional magnetic resonance imaging of the heart that has been used to produce high quality diagnostic images in 274 patients with congenital cardiac disease, ranging in age from 1 day to 66 years. Using a steady state free precession gradient echo technique and parallel imaging, rapid acquisition of the entire cardiac volume is possible during 8 to 15 sequential breath-holds, each lasting between 8 and 15 s. We obtained high-resolution images, with a resolution of 1 mm3, at between 3 and 10 phases of the cardiac cycle.

While images of diagnostic quality were obtained in all cases, in 52 patients there was some degradation due to various factors. Children under 8 years were ventilated, and ventilation was suspended for the breath-holds. For patients breathing spontaneously a novel respiratory navigator technique was developed, using a navigator echo placed over the right hemidiaphragm. This was used successfully in 20 patients, and reduced the misalignment of images obtained during different breath-holds.

Images were analysed using multi-planar reformatting and volume rendering. Image processing took approximately five minutes for each study. End-diastolic images were processed for all patients. Systolic images were also processed in selected cases.

Further improvements in parallel imaging should reduce imaging times further, so that it is possible to obtain the full volume image in a single breath-hold. This will enable imaging of complex anatomy to be obtained using a standard imaging protocol that does not require the operator to understand the cardiac malformation, making the magnetic resonance imaging of congenital cardiac disease faster and more effective.