Background Preoperative physical fitness is predictive of postoperative outcome. Patients with lesser aerobic capacity are at greater risk of postoperative complications, longer hospital stays, and ...mortality. Prehabilitation may improve physical fitness, but it is unknown whether enhanced fitness translates to an improvement in postoperative outcome. Methods This systematic review and meta-analysis aimed to assess the ability of prehabilitation to influence postoperative outcome after intra-abdominal operations. Randomized controlled trials with at least 1 group undergoing a preoperative exercise intervention/prehabilitation were included. The following databases were searched: AMED, CINAHL, EMBASE, PubMed/Medline, and The Cochrane Library. Data extracted from 9 full-articles included author(s), population demographics, type of operation, postoperative measures of outcome, and type of treatment of the prehabilitation and control groups. Methodologic quality was assessed using GRADEpro, and the Cochrane risk of bias tool was used to measure study bias. Results Prehabilitation consisting of inspiratory muscle training, aerobic exercise, and/or resistance training can decrease all types of postoperative complications after intra-abdominal operations (odds ratio: 0.59, 95% confidence interval: 0.38–0.91, P = .03). It is unclear from our meta-analysis whether prehabilitation can decrease postoperative length of stay, because the number of studies that examined length of stay was small ( n = 4). No postoperative mortality was reported in any study, and conclusions could not be drawn on the ability of exercise to influence operative mortality. The methodologic quality of studies was, however, “very low.” Conclusion Prehabilitation appears to be beneficial in decreasing the incidence of postoperative complications; however, more high-quality studies are needed to validate its use in the preoperative setting.
Pico-plankton and nano-plankton are generally thought to represent a negligible fraction of the total particulate organic carbon (POC) export flux in oligotrophic gyres due to their small size, slow ...individual sinking rates, and tight grazer control that leads to high rates of recycling in the euphotic zone. Based upon recent inverse modeling and network analysis however, it has been hypothesized that pico-plankton, including the cyanobacteria Synechococcus and Prochlorococcus, and nano-plankton contribute significantly to POC export, via formation and gravitational settling of aggregates and/or consumption of those aggregates by mesozooplankton, in proportion to their contribution to net primary production. This study presents total suspended particulate (>0.7 μm) and particle size-fractionated (10–20 μm, 20–53 μm, >53 μm) pigment concentrations from within and below the euphotic zone in the oligotrophic subtropical North Atlantic, collected using Niskin bottles and large volume in-situ pumps, respectively. Results show the indicator pigments for Synechococcus, Prochlorococcus and nano-eukaryotes are; (1) found at depths down to 500 m, and; (2) essentially constant, relative to the sum of all indicator pigments, across particle size fractions ranging from 10 μm to >53 μm. Based upon the presence of chlorophyll precursor and degradation pigments, and that in situ pumps do not effectively sample fecal pellets, it is concluded that these pigments were redistributed to deeper waters on larger, more rapidly sinking aggregates likely by gravitational settling and/or convective mixing. Using available pigment and ancillary data from these cruises, these Synechococcus, Prochlorococcus and nano-plankton derived aggregates are estimated to contribute 2–13% (5 ± 4%), 1–20% (5 ± 7%), and 6–43% (23 ± 14%) of the total sediment trap POC flux measured on the same cruises, respectively. Furthermore, nano-eukaryotes contribute equally to POC export and autotrophic biomass, while cyanobacteria contributions to POC export are one-tenth of their contribution to autotrophic biomass. These field observations provide direct evidence that pico- and nano-plankton represent a significant contribution to the total POC export via formation of aggregates in this oligotrophic ocean gyre. We suggest that aggregate formation and fate should be included in ecosystem models, particularly as oligotrophic regions are hypothesized to expand in areal extent with warming and increased stratification in the future.
How well can we quantify dust deposition to the ocean? Anderson, R. F.; Cheng, H.; Edwards, R. L. ...
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
11/2016, Letnik:
374, Številka:
2081
Journal Article
Recenzirano
Odprti dostop
Deposition of continental mineral aerosols (dust) in the Eastern Tropical North Atlantic Ocean, between the coast of Africa and the Mid-Atlantic Ridge, was estimated using several strategies based on ...the measurement of aerosols, trace metals dissolved in seawater, particulate material filtered from the water column, particles collected by sediment traps and sediments. Most of the data used in this synthesis involve samples collected during US GEOTRACES expeditions in 2010 and 2011, although some results from the literature are also used. Dust deposition generated by a global model serves as a reference against which the results from each observational strategy are compared. Observation-based dust fluxes disagree with one another by as much as two orders of magnitude, although most of the methods produce results that are consistent with the reference model to within a factor of 5. The large range of estimates indicates that further work is needed to reduce uncertainties associated with each method before it can be applied routinely to map dust deposition to the ocean. Calculated dust deposition using observational strategies thought to have the smallest uncertainties is lower than the reference model by a factor of 2-5, suggesting that the model may overestimate dust deposition in our study area.
This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’.
A systematic review and network meta-analysis were performed to answer the following research question: Are there differences in the risk and the intensity of tooth sensitivity (TS) among eight light ...activation systems for in-office bleaching in adults?
Randomized controlled trials (RCTs) that compared at least two different in-office bleaching light activations were included. The risk of bias (RoB) was evaluated with the RoB tool version 1.0 from the Cochrane Collaboration tool. A random-effects Bayesian mixed treatment comparison (MTC) model was used independently for high- and low-concentration hydrogen peroxide. The certainty of the evidence was evaluated using the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) approach. A comprehensive search was performed in PubMed, Bridge Base Online (BBO), Latin American and Caribbean Health Sciences Literature database (LILACS), Cochrane Library, Scopus, Web of Science, and grey literature without date and language restrictions on April 23, 2017 (updated on September 26, 2019). Dissertations and theses, unpublished and ongoing trials registries, and IADR (International Association for Dental Research) abstracts (2001-2019) were also searched.
After title and abstract screening and the removal of duplicates, 32 studies remained. Six were considered to be at low RoB, three had high RoB, and the remaining had an unclear RoB. The MTC analysis showed no significant differences among the treatments in each network. In general, the certainty of the evidence was graded as low due to unclear RoB and imprecision.
There is no evidence that the risk and intensity of TS are affected by light activation during in-office bleaching.
226Ra (half-life 1,600 yr) and 228Ra (half-life 5.75 yr) were used as tracers to determine seasonal changes in groundwater input to the Pettaquamscutt estuary from June 1999 to June 2000. Ra isotopes ...were observed to be in excess of activities due to input from streams, Rhode Island Sound water, and particle desorption. The source of excess 226Ra and 228Ra within the estuary is attributed to groundwater transport of Ra derived from the weathering of bedrock within the Pettaquamscutt watershed. Short-lived 224Ra (half-life 3.66 d) was used to calculate an average residence time of the estuary of $8 \pm 4\>d$. Box models used to constrain seasonal changes in groundwater input to the estuary indicate highest groundwater input in the summer $(6.4\!\!-\!\!20\>L\>m^{-2}\>d^{-1})$ and lowest values in the winter $(2.1\!\!-\!\!6.9\>L\>m^{-2}\>d^{-1})$. These Ra-derived groundwater fluxes are similar to rates of aquifer recharge over the annual cycle. Using these Ra-derived groundwater fluxes, the input of inorganic nitrogen and phosphorus from groundwater to the Pettaquamscutt was estimated at $61\!\!-\!\!180\>mmol\>m^{-2}\>yr^{-1}$ and $4.4\!\!-\!\!13\>mmol\>m^{-2}\>yr^{-1}$, respectively.
Purpose: White-matter tract segmentation in patients with brain pathology can guide surgical planning and can be used for tissue integrity assessment. Recently, TractSeg was proposed for automatic ...tract segmentation in healthy subjects. The aim of this study was to assess the use of TractSeg for corticospinal-tract (CST) segmentation in a large cohort of patients with brain pathology and to evaluate its consistency in repeated measurements. Methods: A total of 649 diffusion-tensor-imaging scans were included, of them: 625 patients and 24 scans from 12 healthy controls (scanned twice for consistency assessment). Manual CST labeling was performed in all cases, and by 2 raters for the healthy subjects. Segmentation results were evaluated based on the Dice score. In order to evaluate consistency in repeated measurements, volume, Fractional Anisotropy (FA), and Mean Diffusivity (MD) values were extracted and correlated for the manual versus automatic methods. Results: For the automatic CST segmentation Dice scores of 0.63 and 0.64 for the training and testing datasets were obtained. Higher consistency between measurements was detected for the automatic segmentation, with between measurements correlations of volume = 0.92/0.65, MD = 0.94/0.75 for the automatic versus manual segmentation. Conclusions: The TractSeg method enables automatic CST segmentation in patients with brain pathology. Superior measurements consistency was detected for the automatic in comparison to manual fiber segmentation, which indicates an advantage when using this method for clinical and longitudinal studies.
The Northeast USA is experiencing severe impacts of a changing climate, including increased winter temperatures and accelerated relative sea level rise (RSLR). The sediment-poor, organic-rich nature ...of many Southern New England salt marshes makes them particularly vulnerable to these changes. In order to assess how marsh accretion has changed over time, we returned to Narragansett Bay, RI where salt marsh vertical accretion rates were documented almost 30 years ago. Using radionuclide tracers (²¹⁰Pb and ²³⁷Cs), we observe no significant change in overall accretion rates (0.27–0.69 cm year⁻¹) compared to historical averages (0.24–0.60 cm year⁻¹), but we document a shift in how these marshes maintain elevation. Organic matter now plays a smaller role in contributing to vertical accretion across all study sites, declining by 22 % on average. We attribute this reduction to potentially higher decomposition rates fueled by higher water temperature. Inorganic matter also contributes less to accretion (declining by 44 % on average at marshes located more internal to the estuary), likely due to diminishing sediment supply in this region. With organic and inorganic solids accounting for less of the total accretion, several of the marshes are experiencing symptoms of swelling, with water and porespace contributing more towards accretion compared to historical values. Accretion rates (0.27–0.45 cm year⁻¹) at these organic-rich (>40 % sediment organic matter) marshes are predominantly lower than the current (30 years) rate of RSLR (0.41 ±0.07 cm year⁻¹). These results, combined with the increased rate of RSLR and the hardened shorelines inhibiting landward migration, call into question the longterm survivability of these marshes.
Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem ...allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical countries. Utilising this database, our objectives were: 1. to determine if H:D relationships differ by geographic region and forest type (wet to dry forests, including zones of tension where forest and savanna overlap). 2. to ascertain if the H:D relationship is modulated by climate and/or forest structural characteristics (e.g. stand-level basal area, A). 3. to develop H:D allometric equations and evaluate biases to reduce error in future local-to-global estimates of tropical forest biomass. Annual precipitation coefficient of variation (PV), dry season length (SD), and mean annual air temperature (TA) emerged as key drivers of variation in H:D relationships at the pantropical and region scales. Vegetation structure also played a role with trees in forests of a high A being, on average, taller at any given D. After the effects of environment and forest structure are taken into account, two main regional groups can be identified. Forests in Asia, Africa and the Guyana Shield all have, on average, similar H:D relationships, but with trees in the forests of much of the Amazon Basin and tropical Australia typically being shorter at any given D than their counterparts elsewhere. The region-environment-structure model with the lowest Akaike's information criterion and lowest deviation estimated stand-level H across all plots to within amedian −2.7 to 0.9% of the true value. Some of the plot-to-plot variability in H:D relationships not accounted for by this model could be attributed to variations in soil physical conditions. Other things being equal, trees tend to be more slender in the absence of soil physical constraints, especially at smaller D. Pantropical and continental-level models provided less robust estimates of H, especially when the roles of climate and stand structure in modulating H:D allometry were not simultaneously taken into account.
Seasonal patterns in the partitioning of phytoplankton carbon during receding sea ice conditions in the eastern Bering Sea water column are presented using rates of 14C net primary productivity ...(NPP), phototrophic plankton carbon content, and POC export fluxes from shelf and slope waters in the spring (March 30–May 6) and summer (July 3–30) of 2008. At ice-covered and marginal ice zone (MIZ) stations on the inner and middle shelf in spring, NPP averaged 76±93mmolCm−2d−1, and in ice-free waters on the outer shelf NPP averaged 102±137mmolCm−2d−1. In summer, rates of NPP were more uniform across the entire shelf and averaged 43±23mmolCm−2d−1 over the entire shelf. A concomitant shift was observed in the phototrophic pico-, nano-, and microplankton community in the chlorophyll maximum, from a diatom dominated system (80±12% autotrophic C) in ice covered and MIZ waters in spring, to a microflagellate dominated system (71±31% autotrophic C) in summer. Sediment trap POC fluxes near the 1% PAR depth in ice-free slope waters increased by 70% from spring to summer, from 10±7mmolCm−2d−1 to 17±5mmolCm−2d−1, respectively. Over the shelf, under-ice trap fluxes at 20m were higher, averaging 43±17mmolCm−2d−1. POC export over the shelf and slope estimated from 234Th deficits averaged 11±5mmolCm−2d−1 in spring and 10±2mmolCm−2d−1 in summer. Average e-ratios calculated on a station-by-station basis decreased by ∼30% from spring to summer, from 0.46±0.48 in ice-covered and MIZ waters, to 0.33±0.26 in summer, though the high uncertainty prevents a statistical differentiation of these data.
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