scholarly journals The tortoise and the hare? Post-fire regeneration in mixed Eucalyptus - Callitris forest

2011 ◽  
Vol 59 (6) ◽  
pp. 575 ◽  
Author(s):  
Ian D. Lunt ◽  
Heidi C. Zimmer ◽  
David C. Cheal

Seedling regeneration after a high intensity wildfire was assessed in a mixed forest dominated by Eucalyptus species and Callitris endlicheri (Parl.) F.M. Bailey. Patterns were compared against the ‘slow seedling’ or ‘tortoise-and-hare’ theory of competitive interactions between gymnosperms and angiosperms. Browsing effects were documented using fenced plots, and seedling density, mortality and height were assessed over 6 years, from 2004–10. Consistent with expectations, Eucalyptus seedlings grew faster than Callitris seedlings in most situations. Callitris seedlings grew faster and produced seed cones sooner in plots with fewer Eucalyptus seedlings compared with plots with dense Eucalyptus seedlings. The local growth rates of Callitris seedlings were not associated with long-term site suitability for Callitris, as many plots with diminutive Callitris seedlings and dense Eucalyptus seedlings were dominated by Callitris trees before the 2003 fire. Contrary to expectations, few Callitris seedlings died during the 6-year period, so competition during the regeneration phase did not regulate co-existence. Strong drought tolerance and the ability to persist in dense, unthinned stands may enable Callitris to persist beneath dense Eucalyptus regeneration. Nevertheless, Callitris seedlings growing with dense Eucalyptus seedlings have a longer primary juvenile period than seedlings in sites with fewer seedling or adult eucalypts, which places these stands at greater risk of mortality in future fires and greater risk of browsing in the meantime.

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
P Huang ◽  
C Liu

Abstract Background Lower systolic blood pressure (SBP) at admission or discharge was associated with poor outcomes in patients with heart failure and preserved ejection fraction (HFpEF). However, the optimal long-term SBP for HFpEF was less clear. Purpose To examine the association of long-term SBP and all-cause mortality among patients with HFpEF. Methods We analyzed participants from the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) study. Participants had at least two SBP measurements of different times during the follow-up were included. Long-term SBP was defined as the average of all SBP measurements during the follow-up. We stratified participants into four groups according to long-term SBP: <120mmHg, ≥120mmHg and <130mmHg, ≥130mmHg and <140mmHg, ≥140mmHg. Multivariable adjusted Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CI) for all-cause mortality associated with SBP level. To assess for nonlinearity, we fitted restricted cubic spline models of long-term SBP. Sensitivity analyses were conducted by confining participants with history of hypertension or those with left ventricular ejection fraction≥50%. Results The 3338 participants had a mean (SD) age of 68.5 (9.6) years; 51.4% were women, and 89.3% were White. The median long-term SBP was 127.3 mmHg (IQR 121–134.2, range 77–180.7). Patients in the SBP of <120mmHg group were older age, less often female, less often current smoker, had higher estimated glomerular filtration rate, less often had history of hypertension, and more often had chronic obstructive pulmonary disease and atrial fibrillation. After multivariable adjustment, long-term SBP of 120–130mmHg and 130–140mmHg was associated with a lower risk of mortality during a mean follow-up of 3.3 years (HR 0.65, 95% CI: 0.49–0.85, P=0.001; HR 0.66, 95% CI 0.50–0.88, P=0.004, respectively); long-term SBP of <120mmHg had similar risk of mortality (HR 1.03, 95% CI: 0.78–1.36, P=0.836), compared with long-term SBP of ≥140mmHg. Findings from restricted cubic spline analysis demonstrate that there was J-shaped association between long-term SBP and all-cause mortality (P=0.02). These association was essentially unchanged in sensitivity analysis. Conclusions Among patients with HFpEF, long-term SBP showed a J-shaped pattern with all-cause mortality and a range of 120–140 mmHg was significantly associated with better outcomes. Future randomized controlled trials need to evaluate optimal long-term SBP goal in patients with HFpEF. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): China Postdoctoral Science Foundation Grant (2019M660229 and 2019TQ0380)


Cancers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2918
Author(s):  
Ioannis A. Ziogas ◽  
Irving J. Zamora ◽  
Harold N. Lovvorn III ◽  
Christina E. Bailey ◽  
Sophoclis P. Alexopoulos

This study evaluates the clinicopathological characteristics and outcomes of children vs. adults with undifferentiated embryonal sarcoma of the liver (UESL). A retrospective analysis of 82 children (<18 years) and 41 adults (≥18 years) with UESL registered in the National Cancer Database between 2004–2015 was conducted. No between-group differences were observed regarding tumor size, metastasis, surgical treatment, margin status, and radiation. Children received chemotherapy more often than adults (92.7% vs. 65.9%; p < 0.001). Children demonstrated superior overall survival vs. adults (log-rank, p < 0.001) with 5-year rates of 84.4% vs. 48.2%, respectively. In multivariable Cox regression for all patients, adults demonstrated an increased risk of mortality compared to children (p < 0.001), while metastasis was associated with an increased (p = 0.02) and surgical treatment with a decreased (p = 0.001) risk of mortality. In multivariable Cox regression for surgically-treated patients, adulthood (p = 0.004) and margin-positive resection (p = 0.03) were independently associated with an increased risk of mortality. Multimodal treatment including complete surgical resection and chemotherapy results in long-term survival in most children with UESL. However, adults with UESL have poorer long-term survival that may reflect differences in disease biology and an opportunity to further refine currently available treatment schemas.


Plant Science ◽  
2015 ◽  
Vol 238 ◽  
pp. 26-32 ◽  
Author(s):  
D.A. Ramírez ◽  
J.L. Rolando ◽  
W. Yactayo ◽  
P. Monneveux ◽  
V. Mares ◽  
...  

2021 ◽  
Vol 20 (3) ◽  
pp. 448-449
Author(s):  
Nathalie Auger ◽  
Brian J. Potter ◽  
Ugochinyere Vivian Ukah ◽  
Nancy Low ◽  
Mimi Israël ◽  
...  

2004 ◽  
Vol 22 (3) ◽  
pp. 514-519 ◽  
Author(s):  
Gerhard Schmidmaier ◽  
Britt Wildemann ◽  
Daniel Ostapowicz ◽  
Frank Kandziora ◽  
Richard Stange ◽  
...  

1994 ◽  
Vol 1 (3) ◽  
pp. 214 ◽  
Author(s):  
Colin J. Yates ◽  
Richard J. Hobbs ◽  
Richard W. Bell

Woodlands dominated by Eucalyptus salmonophloia occur both in the fragmented landscapes of the Western Australian wheatbelt and in the adjacent unfragmented goldfields area. We examined the responses of the unfragmented woodlands to landscape-scale disturbances caused by fire, floods, windstorms and drought. Sites known to have experienced disturbances of these types over the past 50 years all had cohorts of sapling-stage E. salmonophloia and other dominant Eucalyptus species. Sites disturbed either by fire, flood or storm during 1991-92 displayed adult tree mortality and extensive seedling establishment, although rates of establishment and survival varied between sites. No regeneration was observed at equivalent undisturbed sites. These results indicate that landscape-scale disturbances of several types are important drivers of the dynamics of these semi-arid woodlands. Lack of regeneration of fragmented woodlands in the wheatbelt is likely to be due to changed disturbance regimes coupled with altered physical and biotic conditions within remnants. We argue that it may be difficult to identify processes which are important for the long-term persistence of natural ecosystems in fragmented landscapes without reference to equivalent unfragmented areas.


2017 ◽  
Vol 29 (5) ◽  
pp. 1539-1551 ◽  
Author(s):  
Stacy S. Drury ◽  
Brittany R. Howell ◽  
Christopher Jones ◽  
Kyle Esteves ◽  
Elyse Morin ◽  
...  

AbstractThe molecular, neurobiological, and physical health impacts of child maltreatment are well established, yet mechanistic pathways remain inadequately defined. Telomere length (TL) decline is an emerging molecular indicator of stress exposure with definitive links to negative health outcomes in maltreated individuals. The multiple confounders endemic to human maltreatment research impede the identification of causal pathways. This study leverages a unique randomized, cross-foster, study design in a naturalistic translational nonhuman primate model of infant maltreatment. At birth, newborn macaques were randomly assigned to either a maltreating or a competent control mother, balancing for sex, biological mother parenting history, and social rank. Offspring TL was measured longitudinally across the first 6 months of life (infancy) from peripheral blood. Hair cortisol accumulation was also determined at 6, 12, and 18 months of age. TL decline was greater in animals randomized to maltreatment, but also interacted with biological mother group. Shorter TL at 6 months was associated with higher mean cortisol levels through 18 months (juvenile period) when controlling for relevant covariates. These results suggest that even under the equivalent social, nutritional, and environmental conditions feasible in naturalistic translational nonhuman primate models, early adverse caregiving results in lasting molecular scars that foreshadow elevated health risk and physiologic dysregulation.


2022 ◽  
Vol 104-B (1) ◽  
pp. 45-52
Author(s):  
Liam Zen Yapp ◽  
Nick D. Clement ◽  
Matthew Moran ◽  
Jon V. Clarke ◽  
A. Hamish R. W. Simpson ◽  
...  

Aims The aim of this study was to determine the long-term mortality rate, and to identify factors associated with this, following primary and revision knee arthroplasty (KA). Methods Data from the Scottish Arthroplasty Project (1998 to 2019) were retrospectively analyzed. Patient mortality data were linked from the National Records of Scotland. Analyses were performed separately for the primary and revised KA cohorts. The standardized mortality ratio (SMR) with 95% confidence intervals (CIs) was calculated for the population at risk. Multivariable Cox proportional hazards were used to identify predictors and estimate relative mortality risks. Results At a median 7.4 years (interquartile range (IQR) 4.0 to 11.6) follow-up, 27.8% of primary (n = 27,474/98,778) and 31.3% of revision (n = 2,611/8,343) KA patients had died. Both primary and revision cohorts had lower mortality rates than the general population (SMR 0.74 (95% CI 0.73 to 0.74); p < 0.001; SMR 0.83 (95% CI 0.80 to 0.86); p < 0.001, respectively), which persisted for 12 and eighteight years after surgery, respectively. Factors associated with increased risk of mortality after primary KA included male sex (hazard ratio (HR) 1.40 (95% CI 1.36 to 1.45)), increasing socioeconomic deprivation (HR 1.43 (95% CI 1.36 to 1.50)), inflammatory polyarthropathy (HR 1.79 (95% CI 1.68 to 1.90)), greater number of comorbidities (HR 1.59 (95% CI 1.51 to 1.68)), and periprosthetic joint infection (PJI) requiring revision (HR 1.92 (95% CI 1.57 to 2.36)) when adjusting for age. Similarly, male sex (HR 1.36 (95% CI 1.24 to 1.49)), increasing socioeconomic deprivation (HR 1.31 (95% CI 1.12 to 1.52)), inflammatory polyarthropathy (HR 1.24 (95% CI 1.12 to 1.37)), greater number of comorbidities (HR 1.64 (95% CI 1.33 to 2.01)), and revision for PJI (HR 1.35 (95% 1.18 to 1.55)) were independently associated with an increased risk of mortality following revision KA when adjusting for age. Conclusion The SMR of patients undergoing primary and revision KA was lower than that of the general population and remained so for several years post-surgery. However, approximately one in four patients undergoing primary and one in three patients undergoing revision KA died within tenten years of surgery. Several patient and surgical factors, including PJI, were associated with the risk of mortality within ten years of primary and revision surgery. Cite this article: Bone Joint J 2022;104-B(1):45–52.


2013 ◽  
Vol 21 (2) ◽  
pp. 71-84 ◽  
Author(s):  
Guy R. Larocque ◽  
Nancy Luckai ◽  
Shailendra N. Adhikary ◽  
Arthur Groot ◽  
F. Wayne Bell ◽  
...  

Competition in forest stands has long been of interest to researchers. However, much of the knowledge originates from empirical studies that examined the effects of competition. For instance, many studies were focused on the effects of the presence of herbaceous species on the development of tree seedlings or the decrease in individual tree growth with increases in stand density. Several models that incorporate competitive effects have been developed to predict tree and stand growth, but with simplified representations of competitive interactions. While these studies provided guidance useful for forest management, they contributed only partially to furthering our understanding of competitive mechanisms. Also, most competition studies were conducted in single-species stands. As competitive interactions occurring in mixed stands are characterized by a higher degree of complexity than those in single-species stands, a better understanding of these mechanisms can contribute to developing optimal management scenarios. The dynamics of forest stands with at least two species may be affected not only by competition, but also by facilitation or complementarity mechanisms. Thus, knowledge of the mechanisms may provide insight into the relative importance of intra- versus inter-specific competition and whether competition is symmetric or asymmetric. Special attention to the implementation of field experimental designs is warranted for mixed stands. While traditional spacing trials are appropriate for single-species stands, the examination of competitive interactions in mixed stands requires more complex experimental designs to examine the relative importance of species combinations. Forest productivity models allow resource managers to test different management scenarios, but again most of these models were developed for single-species stands. As competitive interactions are more complex in mixed stands, models developed to predict their dynamics will need to include more mechanistic representations of competition.


Vascular ◽  
2017 ◽  
Vol 26 (2) ◽  
pp. 209-215 ◽  
Author(s):  
Sherif Sultan ◽  
Edel P Kavanagh ◽  
Edward Diethrich ◽  
Victor Costache ◽  
Mohamed Sultan ◽  
...  

Traditional therapeutic options for complex thoracoabdominal aneurysm include open repair, hybrid repair or endovascular repair (involving fenestrated or branched endografts). The Streamliner Multilayer Flow Modulator has been available for treatment of thoracoabdominal aneurysms since 2010. Its design permits blood flow to perfuse through the mesh in a modus that preserves collateral branch patency, while modulating turbulent to laminar flow within the device. The flow then stagnates over time within the surrounding aneurysm sac. Significant complications, including paraplegia, renal failure and cerebrovascular accident, are much lower with Streamliner Multilayer Flow Modulator treatment. Application of the Streamliner Multilayer Flow Modulator to complex aortic pathologies presents a novel solution to an, as of yet, unmet clinical need, and has resulted in promising clinical outcomes when compared to existing solutions. The Streamliner Multilayer Flow Modulator offers potential for treatment of thoracoabdominal aortic pathologies in patients and is not just confined to those with complexity that dictates no other management options. While current literature illustrates that there is a decreased risk of mortality and associated complications when this new disruptive technology is utilised, there is still a need for prospective, long-term clinical trials, as well as comparative trials to accurately assess outcomes of Streamliner Multilayer Flow Modulator treatment that are both precise and reproducible. This article is a review of current clinical literature regarding contemporary flow modulating technology compared with open, branched and fenestrated managements, presenting early outcomes.


Sign in / Sign up

Export Citation Format

Share Document