Using museum and literature data, we characterize faunal turnover in bivalves and brachiopods of the North American Midcontinent over approximately 12.5 Myr spanning the Pennsylvanian/Permian ...boundary. The two groups experienced indistinguishable rates of background faunal turnover but differed in the type and timing of elevated turnover episodes. Bivalves underwent an episode of elevated first appearance in the Missourian Series whereas brachiopods underwent an episode of elevated disappearance in the Wolfcampian Series. In neither group does turnover history strongly correlate to long-term changes in basinal lithofacies, which reflect evolution of regional climate. Comparison with other time intervals and basins suggests that magnitude and frequency of turnover episodes during the late Paleozoic was intermediate between the more episodic early Paleozoic and less episodic Mesozoic.
A combination of a stratigraphic simulation package (STRATA) and an evolutionary-ecological model (BIOSTRAT) can be used to simulate the distribution of species within a sequence stratigraphic ...framework. BIOMODULE is an extension of this model approach in that it facilitates the visualization and interpretation of those simulations and their input data. Environmental factors (e.g., sea-level changes or sedimentation rates) and ecological factors (preferred water depth, depth tolerance, abundance) that determine the spatial and temporal distribution of species are easily and quickly investigated. In addition, BIOMODULE can be used to compile the stratigraphic first and last appearances of those species and export them into available graphic correlation software packages (Conop9 and GraphCor). This can be used to test the graphic correlation technique and investigate its accuracy and precision under a range of different conditions (e.g., different stratigraphic architectures and sampling densities) since the true correlation of the different sections is already known.
A compilation of species occurrences in a chronostratigraphic framework of depositional sequences from a 250,000 km2 area in the eastern United States is used to test for coordinated stasis in Middle ...and Upper Ordovician articulate brachiopods. Two rapid pulses of turnover in brachiopod species separate three periods of relatively lower turnover (ecologic-evolutionary EE subunits) that range from 3 to 9 m.y. in duration. Turnover within these EE subunits is characterized by high levels of percent species origination (ca. 60%) and percent species extinction (ca. 80%) and low levels of percent species persistence (<10%), all of which fall outside the range reported for coordinated stasis. Turnover between EE subunits is characterized by low levels of percent species holdover and percent species carryover (ca. 10% or less) and is consistent with coordinated stasis, although turnover pulses are driven largely by pulses in either extinction or origination, and not by pulses in both, as reported for coordinated stasis. Taken together, although these data display a marked bimodality in turnover, high levels of turnover within EE subunits is inconsistent with a pattern of coordinated stasis. Turnover rates within these EE subunits are much higher than previous global estimates for Cambro-Ordovician brachiopods or Phanerozoic marine species and indicate that local extirpation and migration play a significant role in regional biodiversity dynamics. Despite the high level of turnover observed within these EE subunits, some level of ecologic stability occurs because abundant genera persist throughout entire EE subunits. Ordovician species in this study behaved relatively independently of other taxa and were not tightly integrated as suggested by the broadly overlapping taxon abundance curves, the shifting habitat preference of some taxa, the piecemeal turnover between EE subunits, and the continuous creation of new species associations due to background levels of turnover within EE subunits. Turnover within EE subunits was associated with relatively stable or only mildly fluctuating environments. Rapid turnover between EE subunits was caused by extreme perturbations to the regional or possibly global ocean-climate system.
Purpose
To compare the frequency of minimally invasive surgical approach to hysterectomy between two time periods, during which the use of the robotic technique has rapidly increased.
Methods
This ...study is a retrospective review of 623 consecutive patients who underwent hysterectomy for benign indications at the Division of Minimally Invasive Gynecologic Surgery via laparoscopic, robotic, laparotomy, mini-laparotomy and vaginal approaches from July 2004 to June 2010. “Early period” refers to the first 311 patients, and “late period” refers to the remaining 312 patients.
Results
The characteristics of patients from the early and late periods were comparable in terms of age, BMI and uterine weight. The rates of hysterectomy by laparotomy, traditional laparoscopy, robotic, vaginal, and mini-laparotomy were significantly different between the early and late periods (17.7 to 5.4 %, 39.5 to 17.6 %, 23.8 to 64.1 %, 5.8 to 4.8 % and 13.2 to 8 %, respectively,
P
< 0.01), with the overall rates of hysterectomies completed via a minimally invasive approach increasing from 82.3 to 94.6 %, respectively (
P
< 0.01). There were no differences in surgical complications between the two periods.
Conclusion
Increased utilization of a robotic approach to hysterectomy correlates with decreasing rates of abdominal hysterectomy concurrent with decreasing rates of traditional laparoscopic hysterectomy. This shift in surgical approach to hysterectomy, while beneficial in increasing the rates of minimally invasive approach to hysterectomy, may have significant economic implications due to the higher cost of robotic surgery.
A hierarchical branching model is presented that tracks diversity of lineages and paraclades simultaneously. It is based on three parameters: (1) lineage origination within a paraclade, (2) lineage ...origination that founds new paraclades, and (3) lineage extinction. The model assumes stochastic constancy of evolutionary rates and, therefore, exponential growth of diversity is the null expectation. The probabilistic model can be used to generate confidence intervals for exponential growth through Monte Carlo simulation. These confidence intervals can be compared to empirical curves to test the null hypothesis of exponential growth. The analytic solution for paraclade diversity gives the statistical expectation for the probabilistic model. It can be applied to empirical diversity curves of supraspecific taxa to estimate total speciation rate, the intrinsic rate of increase, and the proportion of speciation events that found new paraclades. Two factors were identified with the model that may cause diversity curves for higher taxa (e.g., genera, families) to deviate from simple exponential growth during initial phases of diversification: (1) stochastic fluctuation at low diversity, and (2) taxonomic structure (i.e., species/genus ratio). These sources of variability should be evaluated before macroevolutionary explanations for specific diversity trends are invoked. Two kinds of evolutionary radiations were investigated with this model: (1) prolonged periods of low diversity (macroevolutionary lag) in cheilostome bryozoans and mammals prior to their main phases of diversification, and (2) rapid bursts in diversity of bivalves following the late Permian and end-Cretaceous mass extinctions. In all cases these patterns were found to deviate significantly from the null expectation of exponential growth lending support to previous macroevolutionary explanations. Finally, rates of speciation during radiations were compared to rates of speciation during background times for articulate brachiopods, cheilostome bryozoans, bivalves, and mammals. Speciation events that found new paraclades tend to make up a larger proportion of total speciation events during radiations compared to background times indicating that the opportunity for new adaptive zones to be filled at higher taxonomic levels is proportionately higher during these periods of increased evolutionary activity, and is not simply a result of an increased frequency of speciation.
Cluster analysis reveals eight biofacies during a time of faunal turnover and regional oceanographic change in the middle Upper Ordovician of central Kentucky. These biofacies are arranged along a ...deep-water to shallow-water gradient, with the dalmanellid and the Sowerbyella biofacies in offshore facies, the Rafinesquina, the atrypid, and the ramose trepostome biofacies in deep-subtidal to shallow-subtidal facies, the Constellaria-Cyclonema and the Rhynchotrema biofacies in the shallow-subtidal facies, and the Solenopora-Hebertella biofacies in sand-shoal facies. These biofacies are not discrete, but rather they share a large number of taxa suggesting that they are arbitrary subdivisions of a depth-related ecological gradient. Nonetheless, they are useful as a point of comparison with other studies of this time interval in the eastern United States. Previous lower and middle Upper Ordovician biofacies studies portray a similar pattern of plectorthines and rhynchonellaceans in the shallow subtidal, strophomenids in the deep subtidal, and dalmanellids and plectambonitaceans in the offshore, indicating an overall temporal consistency to many of these biofacies at suprageneric taxonomic levels. Similarly, values of preferred depth, depth tolerance, and peak abundance of most taxa are generally conserved, and this is particularly true for abundant taxa. Nonetheless, this 2-m.y. record also indicates temporal changes in the occurrence of some biofacies, in the relative abundances of taxa in some biofacies, in the species membership within biofacies, and in values of preferred depth, depth tolerance, and peak abundance for several taxa. Collectively these indicate a dynamic aspect to an ecosystem that otherwise displays several attributes of stability and underscore that ecologic stability should not be viewed as a simple dichotomy between stability and instability. The dynamic aspects of this ecosystem suggest that these biofacies were not governed by extreme degrees of species interactions that resulted in near constancy of biofacies structure. Continuous changes in water temperature, nutrient supply, and turbidity during this time may have been a contributing factor to changes within this ecosystem.
Abstract Objective To compare the perioperative outcomes associated with 2 minimally invasive surgical routes for the hysterectomy of large fibroid uteri. Methods Retrospective review of 84 women ...undergoing hysterectomy via minilaparotomy (n = 54) or robot-assisted laparoscopy (n = 30) for uteri weighing at least 500 g. Outcome measures included hemorrhage (blood loss of 500 mL or more) and postoperative length of stay. Results Unadjusted mean blood loss (560.2 ± 507.4 mL versus 165.0 ± 257.5 mL, P < 0.001), rate of hemorrhage (40.7% versus 6.7%, P = 0.001, odds ratio 6.1 95% confidence interval 1.5–24.2), and rate of blood transfusion (14.8% versus 0%, P = 0.03 ) were all higher with minilaparotomy than with robot-assisted surgery, while the median postoperative stay was significantly shorter with robotic surgery (2 range 1–4 days versus 1 range 0–7 days, P < 0.01). After adjusting for differences in uterine weight using a multivariate linear regression analysis, the mean blood loss and the rate of hemorrhage were no longer significantly different between the 2 groups. Conclusion The minilaparotomy approach may be used to remove very large uteri and does not require specialized and expensive equipment, or advanced endoscopic training. The robotic approach, when feasible, allows for early postoperative discharge.
We performed sensitivity experiments with the global climate model GENESIS on two stages of the Upper Ordovician (Caradocian, ∼454 Ma; Ashgillian, ∼446 Ma) under a range of atmospheric
pCO
2 values ...(8–18× PAL; Pre-industrial Atmospheric Level), high and low sea level, and two values of poleward ocean heat transport in order to determine the importance of these variables on global cooling. We then coupled a three-dimensional ice sheet model to the global climate model in order to investigate the necessary boundary conditions for ice sheet formation. All simulations with a high sea level and normal heat transport remain free of ice sheets, even with
pCO
2 levels as low as 8× PAL. In the Caradocian simulations, ice sheets form in three scenarios: (1) with
pCO
2 of 8× PAL and a low sea level and normal poleward ocean heat transport, (2) with
pCO
2 of 8× PAL and a high sea level and reduced (50% of normal) poleward ocean heat transport, and (3) with
pCO
2 of 15× PAL and a low sea level and reduced poleward ocean heat transport. In the Ashgillian simulations, ice sheets form in only two scenarios: (1) with
pCO
2 of 8× PAL and a low sea level and normal poleward ocean heat transport, or (2) with
pCO
2 of 8× PAL and a high sea level and reduced poleward ocean heat transport. The ice sheets in the Ashgillian experiments are larger and thicker than the ice sheets in the Caradocian simulations because the southward movement of Gondwana increased land area in the higher southern latitudes where ice sheets could grow. The threshold for glaciation under Ashgillian paleogeography is 8× PAL and either a low sea level (exposed shelves) or a reduced poleward ocean heat transport. While the paleogeographic evolution and a drop in
pCO
2 during the Late Ordovician cooled the global climate, changes in additional factors were required to initiate ice sheet formation, such as a drop in sea level, a reduction in poleward ocean heat transport, or a combination of both.
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