scholarly journals Predatory plants and patchy cows: modeling cattle interactions with toxic larkspur amid variable heterogeneity

2018 ◽  
Author(s):  
Kevin Jablonski ◽  
Randall Boone ◽  
Paul Meiman

The most common explanations for the evolution and persistence of herd behavior in large herbivores relate to decreased risk of predation. However, poisonous plants such as larkspur (Delphinium spp.) can present a threat comparable to predation. In the western United States, larkspur diminishes the economic and ecological sustainability of cattle production by killing valuable animals and restricting management options. Recommendations for mitigating losses have long focused on seasonal avoidance of pastures with larkspur, despite little evidence that this is practical or effective. Our ongoing research points to the cattle herd itself as the potential solution to this seemingly intractable challenge and suggests that larkspur and forage patchiness may drive deaths. In this paper, we present an agent-based model that incorporates neutral landscape models to assess the interaction between plant patchiness and herd behavior within the context of poisonous plants as predator and cattle as prey. The simulation results indicate that larkspur patchiness is indeed a driver of toxicosis and that highly cohesive herds can greatly reduce the risk of death in even the most dangerous circumstances. By placing the results in context with existing theories about the utility of herds, we demonstrate that grouping in large herbivores can be an adaptive response to patchily distributed poisonous plants. Lastly, our results hold significant management-relevant insight, both for cattle producers managing grazing in larkspur habitat and in general as a call to reconsider the manifold benefits of herd behavior among domestic herbivores.

2018 ◽  
Author(s):  
Marco Sciaini ◽  
Matthias Fritsch ◽  
Cédric Scherer ◽  
Craig Eric Simpkins

AbstractNeutral landscape models (NLMs) simulate landscape patterns based on theoretical distributions and can be used to systematically study the effect of landscape structure on ecological processes. NLMs are commonly used in landscape ecology to enhance the findings of field studies as well as in simulation studies to provide an underlying landscape. However, their creation so far has been limited to software that is platform dependent, does not allow a reproducible workflow or is not embedded in R, the prevailing programming language used by ecologists.Here, we present two complementary R packages NLMR and land-scapetools, that allow users to generate, manipulate and analyse NLMs in a single environment. They grant the simulation of the widest collection of NLMs found in any single piece of software thus far while allowing for easy manipulation in a self-contained and reproducible workflow. The combination of both packages should stimulate a wider usage of NLMs in landscape ecology. NLMR is a comprehensive collection of algorithms with which to simulate NLMs. landscapetools provides a utility toolbox which facilitates an easy workflow with simulated neutral landscapes and other raster data.We show two example applications that illustrate potential use cases for NLMR and landscapetools: First, an agent-based simulation study in which the effect of spatial structure on disease persistence was studied. Here, spatial heterogeneity resulted in more variable disease outcomes compared to the common well-mixed host assumption. The second example shows how increases in spatial scaling can introduce biases in calculated landscape metrics.Simplifying the workflow around handling NLMs should encourage an uptake in the usage of NLMs. NLMR and landscapetools are both generic frameworks that can be used in a variety of applications and are a further step to having a unified simulation environment in R for answering spatial research questions.


2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S86-S86
Author(s):  
Macy Zou ◽  
Ronald Kelly ◽  
Betty Chinda ◽  
Mckenzie Braley ◽  
Tony Zhang ◽  
...  

Abstract Frailty Index (FI), polypharmacy and cognition status are significant health concerns in older adults. We conducted this study to investigate the interplay of frailty, polypharmacy, and cognition, in determining health outcomes. InterRAI Residential Care (RAI-RC MDS2.0) data were retrieved from residential care homes in Surrey, BC, Canada. Older residents (65+ years) who had RAI-RC records between 2016 and 2018 were used in the analysis (n=976). A deficit accumulation-based FI was generated using 36 variables. Information on polypharmacy and cognition were obtained by accounting the total number of medications and the cognitive performance scale. Information on falls, emergency visits, and mortality were followed. Multivariate Cox proportional hazard models were used to examine the effects of these variables on different outcomes. The FI showed a near Gaussian distribution (median= 0.370 mean= 0.372 SD= 0.143), and increased linearly with age on a logarithm scale (R=0.75, p<0.001). Residents with cognitive impairment showed a higher level of the FI (KW= 863.3, p<0.001). A higher FI was associated with an increased risk of death (HR=15.2 p=0.006) and emergency visits (HR=2.72 p=0.048), adjusting for age, sex, medications, and education levels. Frailty, polypharmacy, and cognition levels are associated and have interactive effects on health outcomes. Ongoing research is to validate the findings with large samples in different health settings, and to understand the underlying processes of the effect. The close relationships between frailty, polypharmacy, and cognition with health outcomes call for effective integrated strategies for healthcare of older adults with multiple complex health problems.


Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2661 ◽  
Author(s):  
Vincent Smets ◽  
Boud Verbeiren ◽  
Martin Hermy ◽  
Ben Somers

Due to changing precipitation patterns induced by climate change, urban planners are confronted with new challenges to effectively mitigate rainfall runoff. An important knowledge gap that needs to be addressed before tackling these challenges is how and to which extent street/drainage grid density and spatial land use configuration influence the amount of runoff. Therefore, a virtual experiment was conducted to assess the influence of grid density and spatial land use configuration on the functional runoff connectivity (Fc), which is a measure of the easiness by which water flows through the landscape. Through the use of a design of experiments approach in combination with the SCS—Curve Number runoff model, a wide variety of neutral landscape models with a fixed percentage of pervious- and impervious cover were generated that maximized the variance of Fc. Correlations between landscape metrics and neutral landscape models were calculated. Our results indicated that, out of the 17 landscape metrics tested, the average impervious cluster area, the number of impervious clusters, the standard deviation of the cluster size, two proximity indexes and the effective impervious area were strongly correlated with Fc throughout all grid scenarios. The relationship between Fc on the one hand and the average impervious cluster area and the effective impervious area on the other hand, was modelled. The average impervious cluster area models showed a relationship with Fc that closely approximated a logarithmic function (R2: 0.49–0.73), while the effective impervious area models were found to have a linear relationship with Fc (R2: 0.63–0.99). A dense grid was shown to cause a strong increase in Fc, demonstrating the effectiveness of an urban grid in channeling and removing runoff. Our results further indicate that fine-grained landscapes with a lot of small impervious clusters are preferred over course-grained landscapes when the goal is to reduce Fc. In highly urbanized landscapes, where the percentage of impervious area is high, small changes in landscape pattern could significantly reduce Fc. By using a downward hydrological modeling approach this research aims to bring more clarity to the underlying variables influencing Fc, rather than trying to generate realistic prediction values.


2000 ◽  
Vol 15 (2) ◽  
pp. 197-203 ◽  
Author(s):  
RUTH AYLETT ◽  
KERSTIN DAUTENHAHN ◽  
JIM DORAN ◽  
MICHAEL LUCK ◽  
SCOTT MOSS ◽  
...  

One of the main reasons for the sustained activity and interest in the field of agent-based systems, apart from the obvious recognition of its value as a natural and intuitive way of understanding the world, is its reach into very many different and distinct fields of investigation. Indeed, the notions of agents and multi-agent systems are relevant to fields ranging from economics to robotics, in contributing to the foundations of the field, being influenced by ongoing research, and in providing many domains of application. While these various disciplines constitute a rich and diverse environment for agent research, the way in which they may have been linked by it is a much less considered issue. The purpose of this panel was to examine just this concern, in the relationships between different areas that have resulted from agent research. Informed by the experience of the participants in the areas of robotics, social simulation, economics, computer science and artificial intelligence, the discussion was lively and sometimes heated.


2014 ◽  
Vol 5 (1) ◽  
pp. 33-40
Author(s):  
S. V Kakorin ◽  
I. A Averkova ◽  
A. M Mkrtumyan

The article presents a literature review of prevalence, prognosis and treatment of overt tactics of chronic heart failure (CHF) in patients with type 2 diabetes mellitus (T2DM). Application of modern pharmacological preparations and instrumental treatment of cardiovascular disease (CVD) increases life expectancy and improves the quality of life of patients with CHF as with normal carbohydrate metabolism (UO), and with type 2 diabetes. However, the risk of cardiovascular mortality (CAS) in patients with type 2 diabetes, compared to having a normal carbohydrate metabolism remains unchanged.Insulin resistance (IR) and compensatory hyperinsulinemia (GI) play a key role in the pathogenesis of type 2 diabetes. Ongoing research in the twentieth century of coronary heart disease (CHD) and heart failure in patients with type 2 diabetes revealed adverse effects of sulfonylurea medications on the metabolic processes in the myocardium and increased risk of death in patients with severe coronary artery disease. In comparison with sulfonylurea drugs, metformin and insulin not only reduces the risk of cardiovascular disease, but also can prevent or delay the development of type 2 diabetes in individuals with impaired glucose tolerance (IGT) and impaired fasting glucose. Metformin acts on the key link of pathogenesis - insulin resistance, affecting the lower incidence of cardiovascular diseases, the development of chronic disease and mortality compared with insulin and sulfonylurea drugs. However, in patients with chronic heart failure is contraindicated the use of thiazolidinediones and metformin is limited tothe severity of CHF I-II FC NYNA. With effective treatment of chronic heart failure by cardiologists in patients with type 2 diabetes, affecting therapy with insulin resistance should be mandatory.


2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e13108-e13108
Author(s):  
Caroline M. Hamm

e13108 Background: Triple negative breast cancer is defined as estrogen (ER), progesterone (PR), and human epidermal growth factor receptor (HER-2) proteins negative. The grade is the degree of similarity of tumor cells to normal cells under microscope and is an important biomarker of overall patient outcomes or prognosis with higher grades having a poor prognosis. As recent chemotherapy trials noted moderately undifferentiated grade 2 tumors showing higher rates of relapse, we hypothesize that grade can also be a predictive biomarker or determinant of response to specific treatment. Methods: We reviewed 305 patient charts of triple negative breast cancer patients from 2004-2017 at Windsor Regional Cancer Center analyzing the significance of grade with respect to oncological variables, survival-time, and time to relapse. Statistical analysis was performed using Fleming-Harrington, Pairwise Testing, and COX regression, where applicable. Results: Univariate analysis showed statistically significance difference in chemotherapy type (P = 0.008) and a marginal one in ER & hormone therapy status (P ~0.09) between the grades. The overall survival rates were 90.12%, 64.4%, and 77.2%, for grade 1, 2, 3 respectively. The overall difference in survival among the three groups was statistically significant, based on Fleming-Harrington test (P = 0.019). Comparing only between grade 2 and grade 3, we found that after five years, grade 2 patients had a 5.5-fold increased risk of death (HR = 5.5; 95% CI 1.2-25.6) and 2-folds higher risk of relapse (HR = 1.9; 95% CI 1.1-3.2). Grade 3 does significantly better than grade 2 in time to relapse with relapse rates of 70%, 55.6 %, and 75.6%, respectively for grades 1, 2, and 3 (P = 0.04). Conclusions: Tumor grade has a significant positive predictive value in determining relapse with grade 2 tumors demonstrating poorer disease-free survival as compared to grade 1 & 3, less time to relapse, and increased risk of death. This has implications in stratifying triple negative breast cancer patients by grade in future clinical trials while ongoing research yields new targets for chemotherapy.


2021 ◽  
Vol 42 (03) ◽  
pp. 436-448
Author(s):  
Alicia B. Mitchell ◽  
Allan R. Glanville

Abstract Pseudomonas and Burkholderia are gram-negative organisms that achieve colonization within the lungs of patients with cystic fibrosis, and are associated with accelerated pulmonary function decline. Multidrug resistance is a hallmark of these organisms, which makes eradication efforts difficult. Furthermore, the literature has outlined increased morbidity and mortality for lung transplant (LTx) recipients infected with these bacterial genera. Indeed, many treatment centers have considered Burkholderia cepacia infection an absolute contraindication to LTx. Ongoing research has delineated different species within the B. cepacia complex (BCC), with significantly varied morbidity and survival profiles. This review considers the current evidence for LTx outcomes between the different subspecies encompassed within these genera as well as prophylactic and management options. The availability of meta-genomic tools will make differentiation between species within these groups easier in the future, and will allow more evidence-based decisions to be made regarding suitability of candidates colonized with these resistant bacteria for LTx. This review suggests that based on the current evidence, not all species of BCC should be considered contraindications to LTx, going forward.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1947-1947
Author(s):  
Meletios A. Dimopoulos ◽  
Efstathios Kastritis ◽  
Maria Roussou ◽  
Maria Gavriatopoulou ◽  
Magdalini Migkou ◽  
...  

Abstract Abstract 1947 The introduction of novel agents and improvements in supportive care over the last years resulted in a significant improvement of the overall survival (OS) of myeloma patients (Brenner et al Blood 2008, Kumar et al Blood 2008, Kastritis et al Leukemia 2009). However, these retrospective studies indicated that this survival benefit was more pronounced in younger patients while in older patients there was only a marginal improvement in outcome. Randomized studies have shown that upfront use of thalidomide with melphalan and prednisone (MPT) offers superior progression free survival (PFS) than MP alone, and in some of these studies there was also a survival advantage. Bortezomib with MP was also superior to MP in a randomized study, both in terms of PFS and OS. However, these studies included selected patients that may not be representative of the general population of elderly patients with myeloma. Thus, we analyzed our database in order to assess the effect of the upfront use of novel agents (thalidomide, bortezomib, lenalidomide) in consecutive patients older than 65 who were treated in a single center, in Athens, Greece. Many of these patients had been included in clinical trials; however, several patients who were ineligible because of poor performance status, significant renal impairment or comorbidities were also treated with novel agent-based regimens. Thus, these patients are more representative of the general myeloma population. We included patients who started treatment from January 1995 to January 2010, i.e patients who received similar supportive care. All patients were included in the analysis, regardless of performance status, infections, comorbidities etc. Patients were divided in two groups: those who were treated upfront with conventional regimens (group A, N=76) and those who were treated upfront with novel agent-based regimens (group B, N=115). Demographics of the two groups of patients, including gender and age were similar. Performance status at presentation was also similar among the two groups: 56% of those treated upfront with conventional agents and 57% of those treated upfront with novel agents had an ECOG performance status of 2 or higher. Thirty per cent of patients in group A and 44% of patients in group B were older than 75 years, respectively (p=0.07). The presence of osteolytic bone disease (p=0.313), anemia (Hb <10 g/dl, p=0.139), low platelets (<130,000/ml, p=0.949), albumin <3.5 g/dl (p=0.661), elevated LDH ≥300 IU/L (p=0.412), levels of Bence Jones proteinuria (p=0123), heavy (p=0.220) and light chain isotype (p=0.837) were similar among the two groups. However, patients treated upfront with novel agents presented more often with renal impairment (creatinine ≥2 mg/dl in 29% vs. 16%, p=0.044) and had more often elevated beta2-microglobulin levels (p=0.046) and ISS-3 disease (49% vs. 32%, p=0.1). Response to first line treatment was similar for the two groups: 73% for patients treated with novel agents vs. 67% for patients treated with conventional regimens (p=0.371). The median survival of the patients who were treated with novel agent-based regimens was 47 months while it was 34 months for those who received conventional regimens, but this was not statistically significant (p=0.271). Early death rates (<3 months from the initiation of treatment) were 8% for those treated upfront with novel agents and 11% for those treated with conventional regimens. After adjustment for adverse prognostic factors, such as elevated beta2-microglobulin, renal impairment and advanced age, upfront use of novel agents was associated with a significant reduction in the risk of death (HR=0.621, p=0.029). Subsequently, we performed a multivariate analysis which included established adverse prognostic factors and the upfront use of novel drugs. In this analysis, upfront treatment with novel agents was independently associated with superior outcome and a reduced risk of death (HR=0.626, p=0.033). Other factors independently associated with adverse outcome were ISS stage (ISS-3: HR=2.64, ISS-2: HR=1.25, p=0.032), elevated LDH ≥300 IU/L (HR=3.5, p=0.002) and low platelet counts <130,000/ml (HR=1.68, p=0.038) and age >75 years (HR=2, p=0.002). We conclude that in the general population of elderly patients with MM the upfront use of novel agents is associated with improved survival. Disclosures: Dimopoulos: Ortho-Biotech: Honoraria; Celgene: Honoraria; Millennium: Honoraria.


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