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International audience; The effect of tillage timing on weed community assembly was assessed at four locations in the Northeastern United States by tilling the soil every two weeks from April to September and quantifying the emerged weed community six weeks after each tillage event. Variance partitioning analysis was used to test the relative importance of tillage timing and weather on weed community assembly (106 weed species). At a regional scale, site (75.5% of the explained inertia)-and to a lesser extent, timing-of tillage (18.3%), along with weather (18.1%), shaped weed communities. At a local scale, the timing of tillage explained approximately 50% of the weed community variability. The effect of tillage timing, after partitioning out the effect of weather variables, remained significant at all locations. Weather conditions, mainly growing degree days, but also precipitation occurring before tillage, were important factors and could improve our ability to predict the impact of tillage timing on weed community assemblages. Our findings illustrate the role of disturbance timing on weed communities, and can be used to improve the timing of weed control practices and to maximize their efficacy.

There is no abstract for this paper.

The SynCardia™ total artificial heart (TAH) is the only FDA-approved TAH in the world. The SynCardia™ TAH is a pneumatically driven, pulsatile system capable of flows of >9 L/min. The TAH is indicated for use as a bridge to transplantation (BTT) in patients at imminent risk of death from non-reversible bi-ventricular failure. In the Pivotal US approval trial the TAH achieved a BTT rate of >79%. Recently a multi-center, post-market approval study similarly demonstrated a comparable BTT rate. A major milestone was recently achieved for the TAH, with over 1100 TAHs having been implanted to date, with the bulk of implantation occurring at an ever increasing rate in the past few years. The TAH is most commonly utilized to save the lives of patients dying from end-stage bi-ventricular heart failure associated with ischemic or non-ischemic dilated cardiomyopathy. Beyond progressive chronic heart failure, the TAH has demonstrated great efficacy in supporting patients with acute irreversible heart failure associated with massive acute myocardial infarction. In recent years several diverse clinical scenarios have also proven to be well served by the TAH including severe heart failure associated with advanced congenital heart disease. failed or burned-out transplants, infiltrative and restrictive cardiomyopathies and failed ventricular assist devices. Looking to the future a major unmet need remains in providing total heart support for children and small adults. As such, the present TAH design must be scaled to fit the smaller patient, while providing equivalent, if not superior flow characteristics, shear profiles and overall device thrombogenicity. To aid in the development of a new “pediatric,” TAH an engineering methodology known as “Device Thrombogenicity Emulation (DTE)”, that we have recently developed and described, is being employed. Recently, to further our engineering understanding of the TAH, as steps towards next generation designs we have: (1) assessed of the degree of platelet reactivity induced by the present clinical 70 cc TAH using a closed loop platelet activity state assay, (2) modeled the motion of the TAH pulsatile mobile diaphragm, and (3) performed fluid-structure interactions and assessment of the flow behavior through inflow and outflow regions of the TAH fitted with modern bi-leaflet heart valves. Developing a range of TAH devices will afford biventricular replacement therapy to a wide range of patients, for both short and long-term therapy.

Background Right ventricular failure is a serious complication after left ventricular assist device placement. Case Presentation A 70-year-old male in decompensated heart failure with right ventricular failure after the placement of a left ventricular assist device. A single dual-lumen PROTEKDuo cannula was inserted percutaneously via the internal jugular vein to draw blood from the right atrium and return into the pulmonary artery using the CentriMag system, by passing the failing ventricle. The patient was successfully weaned from right ventricular assist device. Conclusions In comparison to two-cannula conventional procedures, this right ventrivular assist device system improves patient rehabilitation and minimizes blood loss and risk of infection, while shortening procedure time and improving clinical outcomes in right ventricular failure.

Yield stability is fundamental to global food security in the face of climate change, and better strategies are needed for buffering crop yields against increased weather variability. Regional- scale analyses of yield stability can support robust inferences about buffering strategies for widely-grown staple crops, but have not been accomplished. We present a novel analytical approach, synthesizing 2000-2014 data on weather and soil factors to quantify their impact on county-level maize yield stability in four US states that vary widely in these factors (Illinois, Michigan, Minnesota and Pennsylvania). Yield stability is quantified as both 'downside risk' (minimum yield potential, MYP) and 'volatility' (temporal yield variability). We show that excessive heat and drought decreased mean yields and yield stability, while higher precipitation increased stability. Soil water holding capacity strongly affected yield volatility in all four states, either directly (Minnesota and Pennsylvania) or indirectly, via its effects on MYP (Illinois and Michigan). We infer that factors contributing to soil water holding capacity can help buffer maize yields against variable weather. Given that soil water holding capacity responds (within limits) to agronomic management, our analysis highlights broadly relevant management strategies for buffering crop yields against climate variability, and informs region-specific strategies.

With the growth and diversity of mechanical circulatory support (MCS) systems entering clinical use, a need exists for a robust mock circulation system capable of reliably emulating and reproducing physiologic as well as pathophysiologic states for use in MCS training and inter-device comparison. We report on the development of such a platform utilizing the SynCardia Total Artificial Heart (TAH) and a modified Donovan Mock Circulation System (DMCS), capable of being driven at normal and reduced output. With this platform, clinically relevant heart failure hemodynamics could be reliably reproduced as evidenced by elevated left atrial pressure (+112%), reduced aortic flow (−12.6%), blunted Starling-like behavior and increased afterload sensitivity when compared to normal function. Similarly, pressure-volume relationships demonstrated enhanced sensitivity to afterload and decreased Starling-like behavior in the heart failure model. Lastly, the platform was configured to allow the easy addition of a left ventricular assist device (HeartMate II® at 9600 RPM), which upon insertion resulted in improvement of hemodynamics. The present configuration has the potential to serve as a viable system for training and research, aimed at fostering safe and effective MCS device use.

We evaluated interrater agreement across multiple respondents on anecdotal assessments and compared cases in which agreement was obtained with outcomes of functional analyses. Experiment 1 evaluated agreement among multiple respondents on the function of problem behavior for 27 individuals across 42 target behaviors using the Motivation Assessment Scale (MAS) and the Questions about Behavioral Function (QABF). Results showed that at least 4 of 5 respondents agreed on the primary maintaining consequence for 52% (22 of 42) of target behaviors with the MAS and 57% (24 of 42) with the QABF. Experiment 2 examined correspondence between the anecdotal assessment results and functional analysis results for 7 individuals for whom at least 4 of 5 respondents showed agreement in Experiment 1. Correspondence with functional analysis results was observed in 6 of 7 cases with the QABF and in 4 of 7 cases with the MAS. Implications of these outcomes for the utility of anecdotal assessments are discussed.

Cardiac power output has been shown to quantify cardiac reserve. Cardiac reserve is defined as the difference between basal and maximal cardiac performance. We compared cardiac power index to other commonly used hemodynamic parameters to validate its usefulness to stage heart failure patients and determine the optimal time for implantation of mechanical circulatory support. A retrospective study of twenty-eight heart failure patients implanted with mechanical circulatory support was analyzed at three levels of drug therapy. Subjects were further separated into two categories: survived versus deceased. Cardiac power index was the only statistically significant hemodynamic parameter that identified cardiac reserve (pConclusion: Cardiac reserve was a determinant of post-device survival; therefore, these data suggest that device implantation should occur prior to the 0.34 Watts/m2 threshold.

Agricultural weed management has become entrenched in a single tactic—herbicide—resistant crops—and needs greater emphasis on integrated practices that are sustainable over the long term. In response to the outbreak of glyphosate-resistant weeds, the seed and agrichemical industries are developing crops that are genetically modified to have combined resistance to glyphosate and synthetic auxin herbicides. This technology will allow these herbicides to be used over vastly expanded areas and will likely create three interrelated challenges for sustainable weed management. First, crops with stacked herbicide resistance are likely to increase the severity of resistant weeds. Second, these crops will facilitate a significant increase in herbicide use, with potential negative consequences for environmental quality. Finally, the short-term fix provided by the new traits will encourage continued neglect of public research and extension in integrated weed management. Here, we discuss the risks to sustainable agric...

Agroecosystems are inherently complex, and practices aimed at managing one component of the system can have unintended consequences for other components of the system. Management decisions, therefore, can be improved by assessing and understanding the multivariate nature of agricultural systems and the multifunctional character of particular agricultural management practices. The act of simultaneously assessing and evaluating multiple characteristics or functions in agriculture also can be a valuable education and extension activity, because it draws on active and experiential methods of learning and because the process effectively reveals important functions and tradeoffs associated with agroecosystems and their management. Here we introduce a tool (the spider plot) and present a case-study exercise in which we used this tool to evaluate the multiple characteristics and functions of different cover crops within a field day workshop format. We also provide examples of how this approach could be used to assess other management practices or properties of agroecosystems and communicate multivariate concepts within a weed science classroom or extension environment.

Anticoagulation of children on mechanical circulatory support presents a challenge. We implanted 28 devices in children and infants using a consistent anticoagulation protocol. We performed a retrospective review of all children implanted in our program with mechanical assist devices since 1997. Heparin, dipyridamole, and aspirin were used for anticoagulation and antiaggregation. Coagulation monitoring included thromboelastography (TEG), platelet aggregration studies, international normalized ratio, partial thromboplastin time, and platelet count. Twenty-eight children, ages 1 month to 16 years (mean 5.3; median 2.4 years), were implanted for 3-107 days (mean 27; median 17). Eighteen received left ventricular assist devices, seven received biventricular assist devices, and three received total artificial hearts. Adverse events during the 720 days of device support included the following: six (21%) reoperations for bleeding; seven strokes (25%): two fatal, two with a mild residual deficit, and three without deficit; and three (11%) visceral emboli: two fatal and one nonfatal. There were eight deaths (29%). Causes of death were embolic (four), graft failure post-transplantation (one), preimplant anoxic brain damage (two), and postexplant heart failure (one). 24/28 (86%) survived to transplantation or weaning from device and 20/28 (71%) were discharged from the hospital, 10 after transplantation and 10 after native heart recovery. All 20 early survivors survived long term. We describe an anticoagulation protocol based upon TEG and platelet aggregation studies and using heparin, aspirin, and dipyridamole. Adequate anticoagulation is more difficult in children. However, 71% of the patients in our study survived long term.

In the mid-Atlantic region, the demand for organic dairy has provided incentives for farmers to transition their land to organic feed grain production. At the same time, interest in minimum-tillage organic production is growing. Two field experiments were conducted to assess the effects of a first year cover crop and tillage system on weed populations, cash crop yield, and net returns over the 3-yr transition period in a cover crop-soybean (Glycine max (L.) Merr.)-corn (Zea mays L.) feed grain rotation. The cover crop treatments were rye (Secale cereale L.)-hairy vetch (Vicia villosa Roth) (hereafter RYE) and timothy (Phleum pratense L.)-red clover (Trifolium pratense L.) (hereafter TIM). Tillage system treatments were moldboard plow (full tillage, FT) and chisel plow (minimum tillage, MT). Across both experiments, soybean yields ranged from 1190 to 3721 kg ha -1 . Corn grain yields were affected by tillage in the first experiment only, and were 59% higher in FT (9370 kg ha -1 ) compared to MT (5906 kg ha -1 ). Weed abundance was primarily affected by tillage, with densities in corn being 244% higher in MT compared to FT. Cumulative net returns in the first experiment were profit-generating in systems where TIM was the initial cover crop (mean = U.S. $ 317 ha -1 ). Mean cumulative net returns were positive in three of the four treatment combinations in the second experiment (U.S. $ 74-299 ha -1 ). Improved strategies for minimizing the costs associated with fertilization and management of weeds in minimal tillage will be necessary to improve the profitability and sustainability of reduced-tillage organic systems.

Plants require solar radiation for photosynthesis and their growth is directly related to the amount received, assuming that other environmental parameters are not limiting. Therefore, precise estimation of photosynthetically active radiation (PAR) is necessary to enhance overall accuracies of plant growth models. This study aimed to explore the PAR radiant flux in the San Francisco Bay Area of northern California. During the growing season (March through August) for 2 years 2007–2008, the on-site magnitudes of photosynthetic photon flux densities (PPFD) were investigated and then processed at both the hourly and daily time scales. Combined with global solar radiation (R S) and simulated extraterrestrial solar radiation, five PAR-related values were developed, i.e., flux density-based PAR (PPFD), energy-based PAR (PARE), from-flux-to-energy conversion efficiency (fFEC), and the fraction of PAR energy in the global solar radiation (fE), and a new developed indicator—lost PARE percentages (LPR)—when solar radiation penetrates from the extraterrestrial system to the ground. These PAR-related values indicated significant diurnal variation, high values occurring at midday, with the low values occurring in the morning and afternoon hours. During the entire experimental season, the overall mean hourly value of fFEC was found to be 2.17 μmol J−1, while the respective fE value was 0.49. The monthly averages of hourly fFEC and fE at the solar noon time ranged from 2.15 in March to 2.39 μmol J−1 in August and from 0.47 in March to 0.52 in July, respectively. However, the monthly average daily values were relatively constant, and they exhibited a weak seasonal variation, ranging from 2.02 mol MJ−1 and 0.45 (March) to 2.19 mol MJ−1 and 0.48 (June). The mean daily values of fFEC and fE at the solar noon were 2.16 mol MJ−1 and 0.47 across the entire growing season, respectively. Both PPFD and the ever first reported LPR showed strong diurnal patterns. However, they had opposite trends. PPFD was high around noon, resulting in low values of LPR during the same time period. Both were found to be highly correlated with global solar radiation R S, solar elevation angle h, and the clearness index K t. Using the best subset selection of variables, two parametric models were developed for estimating PPFD and LPR, which can easily be applied in radiometric sites, by recording only global solar radiation measurements. These two models were found to be involved with the most commonly measured global solar radiation (R S) and two large-scale geometric parameters, i.e., extraterrestrial solar radiation and solar elevation. The models were therefore insensitive to local weather conditions such as temperature. In particular, with two test data sets collected in USA and Greece, it was verified that the models could be extended across different geographical areas, where they performed well. Therefore, these two hourly based models can be used to provide precise PAR-related values, such as those required for developing precise vegetation growth models.

Most infants and children implanted with ventricular assist devices (VADs) go on to cardiac transplantation. Recovery of dilated cardiomyopathies with the combination left ventricular decompression with a VAD and treatment with maximal medical therapy has been possible in some adults, and may be more feasible in infants and children. We used pulsatile and continuous flow VADs and the total artificial heart (TAH) as bridges to transplantation or to recovery. Candidates for native heart recovery were treated with maximal medical therapy for congestive heart failure and short-term dobutamine prior to weaning off device support. Since 1997, 28 infants and children, ages 1 month to 16 years, were implanted for durations of 3-107 days (mean 27). Eighteen received left VADs (LVAD), seven biventricular assist devices (BiVADs), and three TAHs. Device-related mortality was 7/28 (25%), leaving 21/28 (75%) surviving to transplantation or weaning from device support and 20/28 (71%) discharged from the hospital and currently surviving for 2 months to 9 years. Ten of 11 transplant recipients (90%) have survived 2 to 9 years. All 10 with recovered hearts are alive and well for 2 months to 5 years. Eight of 12 (67%) LVAD patients with dilated hearts recovered. None of the recovery patients were over 6 years old. Infants and children who have failed inotropic therapy may be treated with an LVAD and medical therapy for congestive heart failure anticipating native heart recovery. A variety of devices have been tried. All small LVADs yielded comparable results. Larger and older children also have a chance of recovery, but our experience with them is too small except to note that they do well with larger devices and transplantation.

Keebler et al. [(1)][1] set out an interesting and useful study pertaining to some of the key management issues of veno-arterial extracorporeal membrane oxygenation (ECMO) for refractory cardiogenic shock. As the authors rightly note, avoiding left ventricular distention using a venting strategy is

Community assembly theory provides a useful framework to assess the response of weed communities to agricultural management systems and to improve the predictive power of weed science. Under this framework, weed community assembly is constrained by abiotic and biotic “filters” that act on species traits to determine community composition. We used an assembly approach to investigate the response of weed seed banks to 25 yr of management-related filtering in three different row-crop management systems in southeastern Pennsylvania: organic manure-based, organic legume-based, and conventional. Weed seed banks were sampled in April of 2005 and 2006 and quantified by direct germination in a greenhouse. We also assessed the filtering effects of weed management practices and relationships between assembled seed bank and emergent weed communities by allowing or excluding weed control practices within each management system and measuring emergent weed community response. Germinable weed seed bank densities and species richness in the final year of the study were over 40% and 15% higher, respectively, in the organic systems relative to the conventional system. Seed bank community structure in the organic systems was different from the conventional system, and the relationships between assembled seed banks and the emergent flora varied. Primary tillage, weed control, timing of planting, and fertility management appeared to be the main filters that differentiated weed seed banks in the three systems. Weed life history, emergence periodicity, seed size, and responsiveness to soil fertility and hydrology appeared to be the most important functional traits determining how weed species responded to management-related filters. Our results suggest that management systems can exert strong filtering effects that can persist over relatively long (greater than one growing season) time scales. Legacy effects of community-level filtering might be more important than previously assumed, and should be incorporated into predictive models of weed community assembly.

We develop a new conceptual model we call the Resource Pool Diversity Hypothesis (RPDH) aimed at explaining how soil resource pool diversity may mediate competition for soil resources between weeds and crops. The primary tenets of the RPDH are that (i) in plant communities, the intensity of inter-specific competition can depend upon the degree to which niche differentiation and resource partitioning occur among species, (ii) agricultural systems are unique in that management practices, such as crop rotation, source of fertility and weed management, result in inputs to the soil and (iii) these inputs directly or indirectly become soil resource pools from which crops and weeds may partition resources. The RPDH leads to the novel prediction that along a gradient of increasing cropping system diversity, yield loss due to weed-crop competition (i.e. the impact on yield per unit weed density) for soil resources should decrease. Similarly, the degree to which crops and weeds overlap in soil resource niche breadth (which is determined by species-specific functional traits for resource acquisition), will determine the extent to which weed-crop competition weakens as resource pool diversity increases. While there have been no direct tests of the RPDH, we highlight evidence from the agricultural literature that provides strong support for components of the hypothesis. Validation of the RPDH would have important implications across a broad range of cropping systems for the development of management strategies that aim to reduce yield loss impact per unit weed plant density and the fundamental principles of integrated weed management, such as the concepts of weed thresholds and critical periods.

The transition period to certified organic production can present a significant weed management challenge for growers. Organic certification requires that prohibited fertilizers and pesticides must not have been used for 36 mo before harvest of the first organic crop. Understanding how organic management practices and initial weed seed-bank densities affect weed population dynamics during the transition period may improve weed management efficacy and adoption of organic practices. We examined how tillage systems (full or reduced) and cover crop species planted during the first transition year (rye or a mixture of timothy and red clover) affect the seedling densities of three common annual weed species, common lambsquarters, velvetleaf, and foxtail spp., during the 3-yr transition period. Weed seeds were applied in a one-time pulse at the beginning of the study at three densities, low, medium, and high (60, 460, and 2,100 seeds m−2, respectively), and cumulative seedling densities of each species were assessed annually. Treatment factors had variable and species-specific effects on weed seedling densities. In general, the full-tillage system, with an initial cover crop of timothy and red clover, resulted in the lowest density of weed seedlings following seed-bank augmentation. There was little consistent association between the initial densities of applied weed seeds in the weed seed bank at the start of the transition and weed seedling densities at the end of the transition period. This suggests that when multiple crop and weed cultural management practices are employed during the organic transition period, initial failures in weed management may not necessarily lead to persistent and intractable annual weed species management problems following organic certification.

Summary Experiments comparing conventional and organic systems often report similar yields despite substantially higher weed abundance in the organic systems. A potential explanation for this observation is that weed–crop competition relationships differ between the two types of systems. We analysed weed and crop yield data from the Rodale Institute Farming Systems Trial (FST), which provides a unique 27-year dataset of a conventional (CNV) and two organic [manure (MNR) and legume (LEG)] soyabean (Glycine max (L.) Merr.) and maize (Zea mays L.) cropping systems. Average soyabean yields were similar between the MNR and CNV systems and only slightly reduced in the LEG system, whereas average maize yields did not differ among systems despite the two organic systems having more than four and six times greater weed biomass in soyabean and maize respectively. Plot-level weed biomass–crop yield relationships indicated that weed–crop competition differed between the two organic and CNV systems in maize, and was strongest in the CNV system, intermediate in the LEG system and weakest in the MNR system. These results suggest that organic cropping systems may be able to tolerate a greater abundance of weeds compared to conventional systems and that fertility management within organic systems may influence weed–crop competition.

Weed science has contributed much to agriculture, forestry and natural resource management during its history. However, if it is to remain relevant as a scientific discipline, it is long past time for weed scientists to move beyond a dominating focus on herbicide efficacy testing and address the basic science underlying complex issues in vegetation management at many levels of biological organization currently being solved by others, such as invasion ecologists and molecular biologists. Weed science must not be circumscribed by a narrowly-defined set of tools but rather be seen as an integrating discipline. As a means of assessing current and future research interests and funding trends among weed scientists, the Weed Science Society of America conducted an online survey of its members in summer of 2007. There were 304 respondents out of a membership of 1330 at the time of the survey, a response rate of 23%. The largest group of respondents (41%) reported working on research problems primarily focused on herbicide efficacy and maintenance, funded mainly by private industry sources. Another smaller group of respondents (22%) reported focusing on research topics with a complex systems focus (such as invasion biology, ecosystem restoration, ecological weed management, and the genetics, molecular biology, and physiology of weedy traits), funded primarily by public sources. Increased cooperation between these complementary groups of scientists will be an essential step in making weed science increasingly relevant to the complex vegetation management issues of the 21st century.

Understanding how communities of important soil invertebrates vary with land use may lead to the development of more sustainable land-use strategies. We assessed the abundance and species composition of earthworm communities across six replicated long-term experimental ecosystems that span a gradient in agricultural land-use intensity. The experimental systems include a conventional rowcrop agricultural system, two lower-intensity row-crop systems (no-till and tilled organic input), an early successional old-field system, a 40–60 years old coniferous forest plantation, and an old-growth deciduous forest system. Earthworm populations varied among systems; they were lowest in the most intensively managed row-crop system (107 m

A functional analysis indicated that chronic eye poking exhibited by a woman with profound mental retardation persisted in the absence of social contingencies. We initiated a procedure in which a therapist delivered a punisher (mild reprimand) contingent on eye poking in the presence, but not the absence, of a neutral stimulus (wristbands). Subsequently, eye poking was suppressed when the participant wore the wristbands in novel environments without the reprimand contingency.

With the increase in survival for children with cancer, part of the focus of current research is aimed towards evaluating how these children are adapting psychosocially. Neurocognitive deficits have been well established. However, there are multiple facets encompassing quality of life, including general mental health, lifestyles and health behaviors, and academic and cognitive functioning. The relationship between neurocognitive and psychosocial functioning has yet to be thoroughly evaluated. The purpose of this study was to investigate the relationship between neurocognitive and psychosocial functioning in survivors of brain tumors and acute lymphoblastic leukemia. Data was collected from existing archival database comprised of patients of the at Cook Children's Medical Center in Texas. The sample consisted of 177 patients between the ages of 3 and 12 who were at least two years post-diagnosis. Measures used included the NEPSY and the Behavioral Assessment for Children. Statistical analyses included a several one-way analysis of variances, an independent samples t-test, a univariate analysis of variance, a hierarchical multiple regression, and odds ratio analyses. Results indicated survivors treated with neurosurgery alone appear to be less at risk for developing behavior problems than other treatment modalities. Also, brain tumor survivors demonstrate more problematic behaviors than survivors of acute lymphoblastic leukemia. Visuospatial functioning, diagnosis, and type of treatment were found to be predictive variables of behavior problems. Attention, and perhaps language, deficits may predispose children to more problems in their behavior. It is concluded that there are other factors affecting behavior in this population that were not accounted for in this analysis. It is recommended for future studies to research the individual clinical scales of the Behavior Assessment System for Children, obtain information from multiple informants, study this relationship longitudinally, and research additional factors that may be influencing the relationship between neurocognitive and psychosocial functioning. This provides evidence of risk factors that should be monitored as the child returns home and to school.

Background. Safety and efficacy studies of various mechanical circulatory support devices are important, but may not be strictly comparable. Lacking prospective randomized studies for different devices, we believe that comparison of risk factor analyses may give the surgeon a tool more powerful than current studies for matching a patient with an appropriate device. In this paper, we report risk factor profiles for bridge to transplantation with the CardioWest total artificial heart and summarize reports for other devices. Methods. A multiinstitutional risk factor analysis of the CardioWest total artificial heart, as a bridge to transplantation in 81 patients, was conducted. Univariate analyses were performed on 43 preimplantation prognostic factors. From this group, eight factors were chosen for multivariate analysis. Our results were compared with all recent risk factor analyses for other devices. Results. Independent predictors for death at three intervals by multivariate analysis were as follows: “implant to transplant”: history of smoking (odds ratio, 34); “implant to 30 days after transplant”: history of smoking (odds ratio, 10.00), prothrombin time greater than 16 seconds (odds ratio, 4.76); and “implant to 1 year after transplant”: prothrombin time greater than 16 seconds (odds ratio, 3.85). The major difference between this experience and multiple reported experiences with left ventricular assist devices is that for left ventricular assist devices, but not for the temporary CardioWest total artificial heart, right heart failure, high central venous pressure, and being on a ventilator (with or without sepsis) were independent predictors of mortality. Conclusions. Risk factors for bridge to transplantation with the CardioWest total artificial heart are different from those reported for left ventricular assist devices. Recognition of these risk factor differences may facilitate appropriate device selection. (Ann Thorac Surg 2008;85:1639 ‐ 45) © 2008 by The Society of Thoracic Surgeons

Understanding the role of diversity in the functioning of ecosystems has important implications for agriculture. Previous agricultural research has shown that crop rotation and the use of cover crops can lead to increases in yield relative to monoculture; however, few studies have been performed within the broader context of diversity–ecosystem function theory and in the absence of chemical inputs. We performed a field experiment in SW Michigan, USA, in which we manipulated the number of crop species grown in rotation and as winter cover crops over a 3-year period to test if varying the number of species in a rotation affected grain yield, a critical metric of ecosystem function in row-crops. The experimental design was unique in that no fertilizer or pesticides were used, and the only management variable manipulated was number of species in the rotation, thus providing a strong comparison to grassland diversity–ecosystem function experiments. Treatments included continuous monocultures of three row-crops, corn Zea mays L., soybean Glycine max (L.) Merr., and winter wheat Triticum aestivum L., and 2- and 3-year annual rotations with and without cover crops (zero, one, or two legume/small grain species), encompassing a range of crop diversity from one to six species. Crop yields and weed biomass were measured annually for 3 years and plant available soil nitrogen was measured over the course of the growing season in the final year of the study. In all 3 years, corn grain yield increased linearly in response to the number of crops in the rotation. Corn yields in the highest diversity treatment (three crops, plus three cover crops) were over 100% higher than in continuous monoculture and were not significantly different from the county average for each of the 3 years despite the absence of chemical inputs. Corn yields in the diversity treatments were strongly correlated with the availability of inorganic soil nitrogen, which was likely influenced by the number of different legume species (crops and cover crops) present in the rotation. In soybean and winter wheat, yield differences among crop diversity treatments were also significant, but of lower magnitude (32 and 53%, respectively), and showed little direct relationship to the number of crop species grown in a rotation. Results demonstrate that agricultural research motivated by ecological theory can provide important insights into the functioning of agroecosystems and enhance our understating of the linkages between diversity and ecosystem function. Importantly, these results suggest that reduced chemical inputs do not necessarily result in yield penalties and provide support for incorporation of crop or species diversity when determining how ecosystem services can be included in food, fiber, and biofuel production.

The 70 cc total artificial heart (TAH) has been utilized as bridge to transplant (BTT) for biventricular failure. However, the utilization of 70 cc TAH has been limited to large patients for the low output from the pulmonary as well as systemic vein compression after chest closure. Therefore, the 50 cc TAH was developed by SynCardia (Tucson, AZ) to accommodate smaller chest cavity. We report the first TAH exchange from a 70 to 50 cc due to a fit difficulty. The patient failed to be closed with a 70 cc TAH, although the patient met the conventional 70 cc TAH fit criteria. We successfully closed the chest with a 50 cc TAH.

Shortly after SynCardia total artificial heart (TAH) implant, venovenous extracorporeal membrane oxygenation (ECMO) via a 31 Fr Avalon cannula was used for profound hypoxic lung dysfunction. Immediately after starting ECMO, TAH flow increased by 1.5-2.0 L/min, presumably because of augmented TAH filling by the ECMO jet.

Year to year variation in yield is an inherent risk associated with crop production and many growers rely on intensive mechanical or chemical inputs to preserve crop yield in the face of fluctuating environmental conditions. However, as interest grows in alternative crop management systems which depend less on external inputs, determining the degree to which management systems can impact the temporal yield variability will help the development of sustainable agroecosystems. This study assessed average crop yields and temporal yield variability over a 12-yr period in four agricultural management systems that are part of a long-term cropping systems experiment at the W.K. Kellogg Biological Station (KBS) Long Term Ecological Research (LTER) site in southwestern Michigan. The four systems follow a corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and winter wheat (Triticum aestivum L.) 3-yr rotation under conventional (CT), no-till (NT), low-input (LI), or organic (ORG) management, and each crop phase was present in the rotation four times from 1993 to 2004. Yields were measured each year and crop yield variability was estimated using the coefficient of variation calculated separately for each crop phase. Averaged over the study period, yields in the CT and NT systems were similar across all crop phases of the rotation and of higher magnitude than the LI system only in the winter wheat phase of the rotation. Compared to the other three management systems, yields in the ORG system were lower in the corn and winter wheat phases of the rotation. Yields in the soybean phase were similar across the four management systems. Temporal yield variability differed among management systems and rotation phases and was highest in the ORG system during the soybean (CV = 48%) and winter wheat (CV = 33%) phases of the rotation. Compared to the CT system, yield variability was 40% lower in the LI (corn phase), 33% lower in the NT (soybean phase) and similar in the NT (corn and winter wheat phases) systems. Results of this study suggest that yield and temporal yield variability under alternative management systems such as no-till and low-input can be comparable to that in conventional systems. However, temporal yield variability can be as high or higher in organic cropping systems without external inputs of manure or compost.

Kochia (Kochia scoparia [L.] Schrad.), also known as fireweed, belvedere, burning bush, railroad weed or summer cypress, was first introduced to the USA in the early 1900s as an ornamental plant from Eurasia (Undersander et al. 1990). Although it has been grown as a drought-resistant forage crop, this annual plant is a particularly problematic weed in small grain-cropping systems in North America. Kochia is drought-tolerant, has a deep taproot, and its branched stem can grow to a height of almost 2.5 m, making this species an effective competitor for light, nutrients, and soil moisture. Additionally, kochia can produce thousands of seeds per plant and is able to spread these seeds long distances very quickly due to its ability to disperse (as a “tumbleweed”) during windstorms.

Concern over the consequences of increased weed seed inputs to the soil seed bank during the transition period from conventional to organic production is one obstacle to grower adoption of reduced input and nonchemical weed management strategies. An 11-yr study was established in southwest Montana to investigate the effect of a single pulse of wild oat seeds on subsequent seed bank dynamics. In 1993, wild oat seeds were sown at five densities (0, 20, 80, 320, and 800 seeds m−2) in eight wheat–small grain cropping systems that differed in the number of crops in rotation and fallow periods. Wild oat seed banks were measured each spring from 1994 to 2004 in half of the cropping systems and from 2001 to 2004 in all eight systems. In 1994, seed bank densities in response to the pulse were as much as 11 times higher than controls that received no seeds in 1993. By 1996, after mechanical fallowing of all cropping systems, wild oat seed bank densities were not significantly different from densities in co...

This study evaluated the relationship between diversity and activity-density of carabid beetles and invertebrate weed seed predation in conventional, no-till, and organic management systems in the Midwest USA. Carabid beetles were sampled with pitfall traps and invertebrate seed predation rates of fall panicum and common lambsquarters were assayed with exclosure cages. Total carabid activity-density was over two times higher in the conventional systems compared to the no-till and organic management systems. In contrast, activity-densities of seed-predating carabid species were over three times higher in the no-till compared to the conventional and organic systems. Carabid diversity was higher in the no-till and organic systems compared to the conventional system, and a multivariate analysis showed that carabid community structure was distinct among the three systems. Predation of fall panicum and common lambsquarters seeds was often over two times higher in the no-till compared to the conventional and organic systems, and there was a strong correlation (r > 0.94) between seed removal rates and the total number of carabid seed predators captured in each system.

This case study reports the operative management of a 63-year-old male patient following implantation of the HeartMate II (HMII) left ventricular assist device (LVAD), with a non-compliant left ventricle (LV) and a reduced right ventricular (RV) end-diastolic volume. Intraoperatively, the patient had a thin, fragile LV wall with laminated clot; a ventricular septal defect was encountered during removal of the clot. Along with an aortic valve repair, the LV and the septum were reconstructed with multiple bovine pericardium patches, thus, moderately reducing the RV and LV stroke volume. A difference in cardiac output via a Swan-Ganz catheter (approximately 1.5 l/min) was observed as opposed to the HMII’s estimated flow. The result was later replicated and verified in vitro via the Donovan Mock Circulation System (DMCS), where about 2 l/min lower flow on the HMII system was observed. In conclusion, the HMII flow rate displayed can be inaccurate and should only be used for trending.

There is increasing global demand for food, bioenergy feedstocks and a wide variety of bio-based products. In response, agriculture has advanced production, but is increasingly depleting soil regulating and supporting ecosystem services. New production systems have emerged, such as no-tillage, that can enhance soil services but may limit yields. Moving forward, agricultural systems must reduce trade-offs between production and soil services. Soil functional zone management (SFZM) is a novel strategy for developing sustainable production systems that attempts to integrate the benefits of conventional, intensive agriculture and no-tillage. SFZM creates distinct functional zones within crop row and inter-row spaces. By incorporating decimetre-scale spatial and temporal heterogeneity, SFZM attempts to foster greater soil biodiversity and integrate complementary soil processes at the sub-field level. Such integration maximizes soil services by creating zones of ‘active turnover’, optimized for crop growth and yield (provisioning services); and adjacent zones of ‘soil building’, that promote soil structure development, carbon storage and moisture regulation (regulating and supporting services). These zones allow SFZM to secure existing agricultural productivity while avoiding or minimizing trade-offs with soil ecosystem services. Moreover, the specific properties of SFZM may enable sustainable increases in provisioning services via temporal intensification (expanding the portion of the year during which harvestable crops are grown). We present a conceptual model of ‘virtuous cycles’, illustrating how increases in crop yields within SFZM systems could create self-reinforcing feedback processes with desirable effects, including mitigation of trade-offs between yield maximization and soil ecosystem services. Through the creation of functionally distinct but interacting zones, SFZM may provide a vehicle for optimizing the delivery of multiple goods and services in agricultural systems, allowing sustainable temporal intensification while protecting and enhancing soil functioning.

Introduction: The Thoratec Corporation has over 10,000 patients registered as recipients of the HeartMate II left ventricular assist device (LVAD) worldwide. Although it has undoubtedly prolonged the lifespan of heart failure patients, the most recognized risk associated with these devices is the development of thrombus. In the presence of a small or developing clot, the HeartMate II display module and system monitor indicate that there is a decrease in pump flow, adjusts its pump power and is accompanied by audible and visual alarms when flow rates drop below a fixed threshold established by Thoratec. In contrast, when thrombus completely inhibits flow through the device, the display module and system monitor have failed in previous case studies to indicate that flow has reduced to zero and do not produce any corresponding alarms. Methods: To test the efficacy of the HeartMate II alarms, a cardiovascular simulation tank was used to reproduce the hemodynamics of a typical heart failure patient. The hemodynamics were then improved by the addition of the HeartMate II LVAD and different partial and complete occlusions were applied to the inlet and outlet of the HeartMate II pump. Conclusions: Partially occluding the inflow and/or outflow of the HeartMate II did display changes in flow and presented with alarms when flow was estimated to be below 2.5 L/min; however, complete occlusion of the inflow and/or outflow failed to produce any alarms or accurately measured changes in flow.

The ability to evolve Military Communication and Information Systems (CIS) effectively and affordably is enhanced by the adoption of open and modular system architectures. However, there are a number of issues with actually achieving these benefits in practice. This paper presents the results of an initial system study into blockers to the achievement of the benefits of open and modular systems. In particular, the study and this paper, focuses on the issues associated with: the rapidly evolving Information and Communications Technology landscape; the commercial approach to the procurement of CIS systems; the evolution of such systems in a safe and secure manner.

Left ventricular assist devices (LVADs) are commonly used as either a bridge-to-transplant or a destination therapy. The traditional approach for LVAD implantation is via median sternotomy, but many candidates for this procedure have a history of failed cardiac surgeries and previous sternotomy. Redo sternotomy increases the risk of heart surgery, particularly in the setting of advanced heart failure. Robotics facilitates a less invasive approach to LVAD implantation that circumvents some of the morbidity associated with a redo sternotomy. We compared the outcomes of all patients at our institution who underwent LVAD implantation via either a traditional sternotomy or using robotic assistance. The robotic cohort showed reduced resource utilization including length of hospital stay and use of blood products. As the appropriate candidates become elucidated, robotic assistance may improve the safety and cost-effectiveness of reoperative LVAD surgery.

The dynamics of soil seed banks in crop rotations of corn, soybean, and winter wheat were investigated to determine whether weed seed inputs associated with the winter wheat phases of the rotation were present in the readily germinable fraction of the seed bank in subsequent phases. Two studies were conducted, each in chisel-plowed systems. In one study, we compared seed banks in plots after 8 yr of corn grown continuously and with rotation that included winter wheat and soybean. A second study followed seed bank composition and abundance for 3 yr in plots that were planted to corn and soybean in successive years after planting to winter wheat. Seed banks were measured by direct germination in a heated greenhouse. In the first study, seed banks in plots planted to continuous corn (never planted to winter wheat) and the corn phase of the rotation (winter wheat planted 3 yr earlier) did not differ in species composition or abundance despite significant differences in seed banks in plots that had be...

The current motivating concept underlying our view of invasive plant species is that they are dangerous and destructive invaders that drive native plant communities to extinction and must be eradicated at almost any cost. This negative view of non-native plants has resulted in the adoption and implementation of control efforts that may not be entirely successful and have the potential to result in severe non-target effects. The history of weed control in agroecosystems may provide insights on how to deal with non-native plant species in non-crop-lands, and shed light on some of the potential consequences of current control programs for the environment and for non-target organisms. Alternative research and management foci, based on knowledge gleaned from agricultural systems, may improve the effectiveness and sustainability of non-native plant species management in range- and wildlands.

A trait-based community assembly approach to weed management may enhance our understanding of how weed communities respond to specific management practices and increase the utility of weed management based on ecological principles. Therefore, identifying management practices that operate as assembly filters and the species traits upon which they act is an important first step in developing a more predictive weed science. Here, I report results from a 3-yr investigation of the effects of timing of annual tillage (spring vs. fall) on the annual assembly of arable weed communities. The timing of tillage had consistent and dramatic effects on the composition of weed communities; spring tillage led to weed communities dominated by early emerging spring annual forbs and C4 grasses, and fall tillage led to communities dominated by later-emerging forbs and C3 grasses. Traits determining a species' susceptibility to tillage time likely include germination syndrome and life cycle, both of which influence how species respond to changes in soil resource levels and light availability driven by seasonal disturbance regime. Manipulating the timing of tillage and other major soil disturbances may therefore be an important tool for managers interested in influencing community composition or targeting species with similar germination and life-history traits.

The effects of crop rotation and management system on annual variability in weed communities and crop yields were assessed in a 4-yr study in Michigan. Variability of the weed community and corn yields were assessed using the coefficient of variation (CV) and a multivariate dissimilarity index (Bray-Curtis) that accounted for changes in both weed species abundance and composition. The treatments included two rotations: continuous corn and a corn–corn–soybean–wheat rotation, and two management systems: conventional (CONV) and organic-based (ORG). Weed biomass was significantly higher in the ORG system; however, there was no effect of crop rotation on weed biomass or number of weed species in a treatment (species richness). Annual variability in weed community composition and structure was affected by both crop rotation and management system and was highest in the ORG rotation. In contrast to the weed community, variability in corn yield was highest in the least-diverse cropping system (CONV monoculture), despite that system having a more constant weed community. Corn yield in the ORG rotation was not significantly different from that in the CONV monoculture. Results of this study suggest that management aimed at increasing cropping system diversity may have additional effects on weed communities and crop yields beyond those commonly reported, and these may have important implications for the development of more efficient and sustainable weed and crop management practices.

Background Bridge to transplantation (BTT) is an accepted option when a donor heart is not available. Extensive clinical study has been done with BTT in the adult population, but comparatively fewer data are available in the pediatric population with regard to pulsatile devices. Methods Ten pediatric patients are presented, all of whom underwent BTT or recovery with pneumatic paracorporeal systems. The Berlin Heart bi-ventricular assist device (BVAD) was utilized in 1 patient, the Medos VAD in 4 patients (1 left ventricular assist device [LVAD], 3 BVADs) and the Thoratec VAD in 5 patients (3 BVADs, 2 LVADs). The pediatric population consisted of 3 females and 7 males. Mean age of the population was 7.4 years, weight 25 kg and body surface area (BSA) 0.88 m2. Etiology for heart failure consisted of 4 viral, 3 congenital and 3 idiopathic cardiomyopathies. Before implant, all patients had evidence of progressive cardiac failure despite inotropic support, and 2 patients had been on extracorporeal membrane oxygenation (ECMO). Mean duration on the device was 34.3 days (8 to 107 days). Results Two patients suffered stroke and recovered without sequelae. Two patients died of ischemic stroke and 1 of sepsis. Seven patients survived (6 transplanted and 1 weaned) for a survival rate of 70% compared with survival for ECMO as BTT, which was 40% to 50%. All survivors had complications related to bleeding, thromboembolic events and infections. Conclusions The Thoratec VAD can be placed in small patients with large hearts that can accommodate the available cannulas. The Berlin Heart and the Medos VAD have a selection of ventricles with small stroke volumes. All 3 systems can be used successfully in the pediatric population as BTT with better survival than with ECMO.

BACKGROUND The CardioWest Total Artificial Heart orthotopically replaces both native cardiac ventricles and all cardiac valves, thus eliminating problems commonly seen in the bridge to transplantation with left ventricular and biventricular assist devices, such as right heart failure, valvular regurgitation, cardiac arrhythmias, ventricular clots, intraventricular communications, and low blood flows. METHODS We conducted a nonrandomized, prospective study in five centers with the use of historical controls. The purpose was to assess the safety and efficacy of the CardioWest Total Artificial Heart in transplant-eligible patients at risk for imminent death from irreversible biventricular cardiac failure. The primary end points included the rates of survival to heart transplantation and of survival after transplantation. RESULTS Eighty-one patients received the artificial-heart device. The rate of survival to transplantation was 79 percent (95 percent confidence interval, 68 to 87 percent). Of the 35 control patients who met the same entry criteria but did not receive the artificial heart, 46 percent survived to transplantation (P

Background The SynCardia CardioWest total artificial heart (CardioWest TAH) is a biventricular, orthotopic, pneumatic, pulsatile blood pump driven by an external console. For each ventricle, the length of the blood-flow path is shorter and the inflow and outflow valves are larger than in any other bridge-to-transplant device, resulting in greater blood flow at smaller pre-load. Such a device should be optimal for bridging transplant candidates who have biventricular failure and for whom all other therapies have failed. Methods From January 1, 1993, to April 1, 2002, we prospectively studied 62 consecutive CardioWest TAH implant recipients to document safety and efficacy in bridge to transplantation. We used multisystem monitoring and multidrug therapy for anti-coagulation in 58 patients starting September 1, 1994. Results Before implantation, patients were critically ill with biventricular heart failure. Mortality in this group from the time of implantation until transplantation was 23%. Causes of death during device support included multi-organ failure (6), sepsis (3), and valve entrapment (2). Forty-eight patients underwent transplantation (77%). Forty-two survived to hospital discharge (68% of the total, 88% of those undergoing transplantation). Adverse events included bleeding (20%), device malfunction (5%), fit complications (3%), mediastinal infections (5%), visceral embolus (1.6%), and stroke during support (1.6%). The linearized stroke rate was 0.068 events per patient-year. Conclusions Sixty-eight percent of critically ill transplant candidates for whom medical therapy failed were bridged to transplantation with the CardioWest TAH and survived long-term. Most deaths that occurred during device support were related to pre-implant problems. Infection and stroke were rare events. Therefore, we recommend the CardioWest TAH as the biventricular bridge-to-transplant device of choice.

Metformin, a drug widely used in the treatment of type 2 diabetes, has recently been shown to act on skeletal muscle and liver in part through the activation of AMP-activated protein kinase (AMPK). Whether metformin or the satiety factor leptin, which also stimulates AMPK in muscle, regulates this enzyme in pancreatic islets is unknown. We have recently shown that forced increases in AMPK activity inhibit insulin secretion from MIN6 cells (da Silva Xavier G, Leclerc I, Varadi A, Tsuboi T, Moule SK, and Rutter GA. Biochem J 371: 761–774, 2003). Here, we explore whether 1) glucose, metformin, or leptin regulates AMPK activity in isolated islets from rodent and human and 2) whether changes in AMPK activity modulate insulin secretion from human islets. Increases in glucose concentration from 0 to 3 and from 3 to 17 mM inhibited AMPK activity in primary islets from mouse, rat, and human, confirming previous findings in insulinoma cells. Incubation with metformin (0.2–1 mM) activated AMPK in both human islets and MIN6 β-cells in parallel with an inhibition of insulin secretion, whereas leptin (10–100 nM) was without effect in MIN6 cells. These studies demonstrate that AMPK activity is subject to regulation by both glucose and metformin in pancreatic islets and clonal β-cells. The inhibitory effects of metformin on insulin secretion may therefore need to be considered with respect to the use of this drug for the treatment of type 2 diabetes.