The Circle of Life: The Mathematics of Predator-Prey Dynamics

Some animals hunt other animals to feed themselves; these animals are called predators. Animals who are hunted and eaten are known as prey. What do you think would happen if a predator were introduced to an ecosystem where the prey previously lived without fear of being hunted? Would the new predator eat all the prey animals until they go extinct? Actually, the relationship between predator and prey is far more interesting than this. In this article, we show what the predator-prey relationship looks like over time and explain how scientists can make predictions about future population levels, all using basic mathematics like addition, subtraction, and multiplication

Application of the Two-Variable Model to Simulate a Multisensory Reaction-Time Task

To navigate the world in an efficient manner, the brain seamlessly integrates signals received across multiple sensory modalities. Behavioral studies have suggested that multisensory processing is a winner-take-all sensory response mechanism to some optimal combination of sensory signals. In addition, multiple sensory cues are not always beneficial with some studies showing maladaptive multisensory processing as an identifier of older adults prone to falls from age matched healthy controls. A stalwart of modelling sensory decision-making is the work by (Wong &Wang, 2006) but to date almost all of this research has been focused on unisensory tasks. We extend the reduced two-variable model developed to model an audio-visual speeded reaction-time task. This model consists of a system of ordinary differential equations motivated by biological data to simulate both unisensory and multisensory processing and behavioral responses. The model includes noise to account for trial-to-trial variability and by sampling from a set of model parameters we simulated different ‘participants’ sensory processing. With these straightforward manipulations the model replicates data from multisensory behavioral studies. The results show how biologically motivated mathematical models can be used to probe the potential mechanisms responsible for the observed differences in unisensory and multisensory responses.https://arrow.tudublin.ie/cddpos/1009/thumbnail.jp

Critically Ill Recipients of Weight-Based Fluconazole Meeting Drug-Induced Liver Injury Network Criteria

Background: Fluconazole-associated liver injury is estimated to occur in <10% of patients; however, effect of weight-based fluconazole dosing on liver injury is unknown. Furthermore, no studies have systematically applied the Drug-Induced Liver Injury Network (DILIN) Criteria to identify patients who may have drug-induced liver injury in an intensive care unit (ICU) setting. Objective: This study evaluated how often patients met DILIN criteria when receiving fluconazole daily doses of <6 mg/kg versus ⩾6 mg/kg. Methods: This dual-center, retrospective cohort study was performed in hospitalized critically ill fluconazole recipients. We compared liver function tests (LFTs) upon fluconazole initiation to peak LFTs within 2 weeks after discontinuation using DILIN criteria. The primary objective was to evaluate the number of patients meeting DILIN criteria when receiving fluconazole daily doses of <6 mg/kg versus ⩾6 mg/kg. Secondary objectives were to evaluate incidence of patients meeting DILIN criteria in patients with renal dysfunction, cirrhosis, septic shock, or those receiving a loading dose. Results: Of 248 patients included, 90% had a documented fungal infection or received empiric therapy for suspected invasive candidiasis. In patients receiving <6 mg/kg of fluconazole, 55% (110/199) met DILIN criteria versus 46.9% (23/49) in the ⩾6 mg/kg cohort (P = .20). Only 14.5% of patients meeting DILIN criteria also met the definition for hepatocellular damage. Weight-based fluconazole dose and creatinine clearance <50 mL/min were not independent risk factors for meeting DILIN criteria. However, 77.3% of patients with cirrhosis met DILIN criteria (OR 4.84 [95% confidence interval, CI, 2.61-9.28]) and 76.3% with septic shock met DILIN criteria (OR 4.56 [95% CI, 2.44-8.88]). Conclusion: Weight-based fluconazole dosing did not affect the number of critically ill recipients who met DILIN criteria. However, DILIN criteria may overestimate the incidence of fluconazole-associated liver injury in critically ill patients

Critically-Ill Recipients of Weight-Based Fluconazole Meeting Drug-Induced Liver Injury Network (DILIN) criteria.

Purpose: Fluconazole-associated liver injury is estimated to occur in <10% of patients; however, the effect of weight-based fluconazole dosing on liver injury has not been assessed. This study evaluated how often patients met Drug Induced Liver Injury Network (DILIN) criteria when receiving fluconazole daily doses of <6mg/kg versus ≥6mg/kg. Methods: This multi-center, retrospective cohort study was performed in critically-ill fluconazole recipients hospitalized from January 2009 to December 2012. It included patients who received ≥3 fluconazole doses with ≥1 dose administered in the intensive care unit. Patients were excluded if they were pregnant, presented with acetaminophen toxicity, received fluconazole within 1 week of liver transplantation, or missed >1 fluconazole dose during therapy. We compared liver function tests (LFTs) upon fluconazole initiation to peak LFTs within 2 weeks after fluconazole discontinuation using DILIN criteria. The Fisher’s exact test was used to detect differences in the primary outcome of patients meeting DILIN criteria by weight-based dosing as well as in subgroups of patients with kidney dysfunction, liver disease, septic shock, and those receiving a loading dose. Results: Two-hundred and forty-eight of 767 patients met inclusion criteria; 90% had a documented fungal infection or received empiric therapy for suspected invasive candidiasis. Of the 199 patients receiving <6 mg/kg of fluconazole, 55% met DILIN criteria versus 46.9% of the 49 patients in the ≥6 mg/kg cohort (p=0.20). Only 14.5% of patients meeting DILIN criteria also met the definition for hepatocellular damage. In analysis of subgroups, 77.3% of patients with cirrhosis and 76.3% with septic shock met DILIN criteria (p<0.001 for both compared to those without these conditions). Conclusions: Weight-based fluconazole dosing did not affect the number of critically-ill recipients who met DILIN criteria. However, DILIN criteria may overestimate the incidence of fluconazole-associated liver injury in critically-ill patients

Cardioactive effects of diphenhydramine and curcumin in Daphnia magna

Although used as a model for examining the cardioactive effects of various compounds, the neuromuscular regulation of the heart of the crustacean Daphnia magna (D. magna) is not well understood. In the present study, we sought to determine how the heart rate of D. magna was affected by two previously untested compounds: curcumin and diphenhydramine (DPHM). DPHM produces a number of cardiotoxic side effects in vertebrates, particularly sinus tachycardia. Curcumin acts as a monoamine oxidase inhibitor (MAOI) and was expected toincrease the heart rate of D. magna. DPHM was found unexpectedly to lower the heart rate of D. magna with time. Curcumin increased heart rate when administered in higher concentrations. However, co-administration of curcumin with DPHM negated this effect. These findings may be explained by the potential role of histamine as a sympathetic cardiac neurotransmitter in D. magna

Handling sensitive topics ​in partnership with young people: Reflections on collaboration within a configurative systematic review​

We present reflections on work with a group of young people during a qualitative evidence synthesis about eating disorder related content that can be accessed online. Our aim was to help young peoples’ priorities and concerns be better reflected in the review, so as to better inform the development of policies that affect them. A review team and a small group of young people with experience of this content worked together during the review. Interactive online workshops and other activities helped to refine the review’s focus from an early stage, identified gaps in understanding, informed reviewers’ analyses and affected communication of the review and its findings. Approaches designed to address ethical issues around handling sensitive topics in research were adapted for use in the review and involvement activities. As well as taking steps to promote participation rights for young people, given a pandemic context, the review team made efforts to communicate their own concerns, for example about unanticipated delays. Evaluation findings so far suggest that aiming for a culture of mutual respect can help ensure continued interest for all and support the production of a more impactful systematic review

Maternal well-being and family adaptation during COVID-19 in fragile X syndrome

Mothers of children with fragile X syndrome are at increased risk of experiencing anxiety and depression due to potential genetic risk and to stress associated with parenting a child with significant behavioral, emotional, and educational support needs. During the initial shutdown and subsequent restrictions of the COVID-19 pandemic, mothers of children with fragile X reported experiencing elevated levels of anxiety and depression relative to their usual levels of well-being. Many indicated that the negative consequences of exposure to COVID-19 and related stressors, as well as the impacts of the pandemic on their family, directly affected their anxiety and depression. Mothers reported on specific sources of distress as well as potential sources of resilience and positive adaptation that occurred during the first year of the COVID-19 pandemic