Modelling biological invasions: individual to population scales at interfaces

Extracting the population level behaviour of biological systems from that of the individual is critical in understanding dynamics across multiple scales and thus has been the subject of numerous investigations. Here, the influence of spatial heterogeneity in such contexts is explored for interfaces with a separation of the length scales characterising the individual and the interface, a situation that can arise in applications involving cellular modelling. As an illustrative example, we consider cell movement between white and grey matter in the brain which may be relevant in considering the invasive dynamics of glioma. We show that while one can safely neglect intrinsic noise, at least when considering glioma cell invasion, profound differences in population behaviours emerge in the presence of interfaces with only subtle alterations in the dynamics at the individual level. Transport driven by local cell sensing generates predictions of cell accumulations along interfaces where cell motility changes. This behaviour is not predicted with the commonly used Fickian diffusion transport model, but can be extracted from preliminary observations of specific cell lines in recent, novel, cryo-imaging. Consequently, these findings suggest a need to consider the impact of individual behaviour, spatial heterogeneity and especially interfaces in experimental and modelling frameworks of cellular dynamics, for instance in the characterisation of glioma cell motility

DRIVERS OF ANNUAL FLEDGING IN THE MISSISSIPPI SANDHILL CRANE POPULATION 1991-2018

We studied trends in nesting, number of chicks fledged annually, and their environmental and biotic drivers in the wild population of Mississippi sandhill cranes (Grus canadensis pulla) on Mississippi Sandhill Crane National Wildlife Refuge during 1991-2018. Population size, number of nests, and number of chicks fledged annually increased slowly but significantly over the course of the study. Increases in population size were related to both number of wild-reared chicks fledged annually and number of captive-reared chicks released each year, but wild-reared chicks had significantly higher survivorship than captive-reared chicks. Hurricanes transiently raised mortality rates but only Hurricane Katrina caused a sustained population decline among adult birds. Total population size was positively related to precipitation during the nesting season, while number of chicks fledged annually was negatively related to annual number of extreme heat days and estimates of bobcat (Lynx rufus) occurrence. Cranes displayed high philopatry to their initial nest location and nested repeatedly in the same general home range regardless of the time since an area had last been treated by prescribed burning. Number of chicks fledged annually occurred with approximately equal frequency across management units burned at different times prior to nesting. The results indicate that both biotic and abiotic factors drive population dynamics on the refuge and suggest that additional attention to prescribed burns, predator removal, and behavioral conditioning of captive-reared birds prior to release may promote faster population growth and establishment of a self-sustaining wild population in the future

Can multi-function heat pumps with low-global warming potential refrigerant effectively decarbonize heating for low-income homes?

Electrification of homes is a critical part of reducing greenhouse gas (GHG) emissions. However, space constraints, installation complexity, and the potential impact on energy costs slows the pace of retrofit electrification efforts. Also, the addition of electrical circuits for heat pumps and the increased household electrical demand often necessitates electrical panel upgrades, which increases costs and slows installation. Multi-Function Heat Pumps (MFHPs) use a single compressor to provide heating, cooling, and domestic hot water (DHW) –which represent the most intensive thermal loads of a home –and can ease the process of retrofit electrification. MFHPs are potentially more economical than typical split HVAC heat pumps (HPs) and heat pump water heaters(HPWHs), as they consolidate systems, require fewer circuits, streamline installation, and enable efficiency opportunities, such as recovering waste heat from cooling to heat DHW. The current study evaluates one MFHP product, a split HP with indirect water heater and ducted air handler, using a low-global warming potential (GWP) refrigerant (R454B). This MFHP has a unique defrost operation that pulls heat from the DHW tank instead of the indoor air, which avoids cold drafts on occupants. This allows for better thermal comfort without requiring an electrical resistance backup heater and costly panel upgrades. The MFHP was installed in two low-income apartments, evaluated for ease of installation, and monitored through the heating season to assess reliability, energy efficiency, and performance

A pyridinium derivative from Red Sea soft corals inhibited voltage-activated potassium conductances and increased excitability of rat cultured sensory neurones

BACKGROUND: Whole cell patch clamp recording and intracellular Ca(2+ )imaging were carried out on rat cultured dorsal root ganglion (DRG) neurones to characterize the actions of crude extracts and purified samples from Red Sea soft corals. The aim of the project was to identify compounds that would alter the excitability of DRG neurones. RESULTS: Crude extracts of Sarcophyton glaucum and Lobophyton crassum attenuated spike frequency adaptation causing DRG neurones to switch from firing single action potentials to multiple firing. The increase in excitability was associated with enhanced KCl-evoked Ca(2+ )influx. The mechanism of action of the natural products in the samples from the soft corals involved inhibition of voltage-activated K(+ )currents. An active component of the crude marine samples was identified as 3-carboxy-1-methyl pyridinium (trigonelline). Application of synthetic 3-carboxy-1-methyl pyridinium at high concentration (0.1 mM) also induced multiple firing and reduced voltage-activated K(+ )current. The changes in excitability of DRG neurones induced by 3-carboxy-1-methyl pyridinium suggest that this compound contributes to the bioactivity produced by the crude extracts from two soft corals. CONCLUSION: Sarcophyton glaucum and Lobophyton crassum contain natural products including 3-carboxy-1-methyl pyridinium that increase the excitability of DRG neurones. We speculate that in addition to developmental control and osmoregulation these compounds may contribute to chemical defenses

Experimental and computational analysis of para-hydroxy methylcinnamate following photoexcitation

Para-hydroxy methylcinnamate is part of the cinnamate family of molecules. Experimental and computational studies have suggested conflicting non-radiative decay routes after photoexcitation to its S1(ππ*) state. One non-radiative decay route involves intersystem crossing mediated by an optically dark singlet state, whilst the other involves direct intersystem crossing to a triplet state. Furthermore, irrespective of the decay mechanism, the lifetime of the initially populated S1(ππ*) state is yet to be accurately measured. In this study, we use time-resolved ion-yield and photoelectron spectroscopies to precisely determine the S1(ππ*) lifetime for the s-cis conformer of para-hydroxy methylcinnamate, combined with time-dependent density functional theory to determine the major non-radiative decay route. We find the S1(ππ*) state lifetime of s-cis para-hydroxy methylcinnamate to be ∼2.5 picoseconds, and the major non-radiative decay route to follow the [1ππ*→1nπ*→3ππ*→S0] pathway. These results also concur with previous photodynamical studies on structurally similar molecules, such as para-coumaric acid and methylcinnamate

Alcohol-related behaviours, beliefs, and knowledge regarding cancer risk related to alcohol in the New South Wales LGBTQ+ community

Sexuality and gender diverse (LGBTQ+) people are a priority for cancer control due to differing experience of risk factors for cancer and participation in cancer screening services compared to cisgender and heterosexual people. Alcohol use among LGBTQ+ people is typically higher compared to the general population, but awareness of alcohol-related cancer risk in the LGBTQ+ community is unclear and other alcohol-related behaviours/beliefs (e.g., perceived health risks) have also been under-researched in this community. This technical report details a study conducted in collaboration with ACON and Cancer Institute NSW to examine a range of alcohol-related behaviours and beliefs among LGBTQ+ adults in NSW, including alcohol use patterns, perceived health risks of alcohol use, awareness of alcohol-related cancer risk, and alcohol-related help-seeking behaviours

Bioregions in marine environments: Combining Biological and Environmental Data for Management and Scientific Understanding

Bioregions are important tools for understanding and managing natural resources. Bioregions should describe locations of relatively homogenous assemblages of species occur, enabling managers to better regulate activities that might affect these assemblages. Many existing bioregionalization approaches, which rely on expert-derived, Delphic comparisons or environmental surrogates, do not explicitly include observed biological data in such analyses. We highlight that, for bioregionalizations to be useful and reliable for systems scientists and managers, the bioregionalizations need to be based on biological data; to include an easily understood assessment of uncertainty, preferably in a spatial format matching the bioregions; and to be scientifically transparent and reproducible. Statistical models provide a scientifically robust, transparent, and interpretable approach for ensuring that bioregions are formed on the basis of observed biological and physical data. Using statistically derived bioregions provides a repeatable framework for the spatial representation of biodiversity at multiple spatial scales. This results in better-informed management decisions and biodiversity conservation outcomes.Peer reviewe