Reju Sam John

University of Auckland

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David T. S. Hayman

Massey University

Renata L. Muylaert

Massey University

Jonathan C. Marshall

Massey University

Wantida Horpiencharoen

Massey University

Tigga Kingston

Texas Tech University

Surajit Paul

Manipal Academy of Higher Education

Maria Cristina Rulli

Politecnico di Milano

Nikolas Galli

Politecnico di Milano

Prateek Gupta

Savitribai Phule Pune University

David A. Wilkinson

Inserm

Cooperative Institutions

Massey University

King Mongkut's University of Technology Thonburi

University of California, Berkeley

Pondicherry University

Centre National de la Recherche Scientifique

International Union for Conservation of Nature (Bangladesh)

University of Würzburg

University of Oxford

Savitribai Phule Pune University

Universidade de São Paulo

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Using drivers and transmission pathways to identify SARS-like coronavirus spillover risk hotspots

Nature Communications (2023)

Renata L. Muylaert David A. Wilkinson Tigga Kingston Paolo D’Odorico Maria Cristina Rulli

The emergence of SARS-like coronaviruses is a multi-stage process from wildlife reservoirs to people. Here we characterize multiple drivers-landscape change, host distribution, and human exposure-associated with the risk of spillover of zoonotic SARS-like coronaviruses to help inform surveillance and mitigation activities. We consider direct and indirect transmission pathways by modeling four scenarios with livestock and mammalian wildlife as potential and known reservoirs before examining how access to healthcare varies within clusters and scenarios. We found 19 clusters with differing risk factor contributions within a single country (N = 9) or transboundary (N = 10). High-risk areas were mainly closer (11-20%) rather than far ( < 1%) from healthcare. Areas far from healthcare reveal healthcare access inequalities, especially Scenario 3, which includes wild mammals and not livestock as secondary hosts. China (N = 2) and Indonesia (N = 1) had clusters with the highest risk. Our findings can help stakeholders in land use planning, integrating healthcare implementation and One Health actions.

Spillover effect

Wildlife trade

One Health

10.1038/s41467-023-42627-2

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Citations (10)

Using drivers and transmission pathways to identify SARS-like coronavirus spillover risk hotspots

bioRxiv (Cold Spring Harbor Laboratory) (2022)

Renata L. Muylaert David A. Wilkinson Tigga Kingston Paolo D’Odorico Maria Cristina Rulli

Abstract The emergence of SARS-like coronaviruses is a multi-stage process from wildlife reservoirs to people. Here we characterize multiple drivers—landscape change, host distribution, and human exposure—associated with the risk of spillover of SARS-like coronaviruses to help inform surveillance and mitigation activities. We consider direct and indirect transmission pathways by modeling four scenarios with livestock and mammalian wildlife as potential and known reservoirs before examining how access to healthcare varies within clusters and scenarios. We found 19 clusters with differing risk factor contributions within a single country (N=9) or transboundary (N=10). High-risk areas were mainly closer (11-20%) rather than far (<1%) from healthcare. Areas far from healthcare reveal healthcare access inequalities, especially Scenario 3, which includes wild mammals as secondary hosts. China (N=2) and Indonesia (N=1) had clusters with the highest risk. Our findings can help stakeholders in land use planning integrating healthcare implementation and One Health actions.

Spillover effect

Wildlife trade

10.1101/2022.12.08.518776

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Citations (1)

Data from 'Using drivers and transmission pathways to identify SARS-like coronavirus spillover risk hotspots'

Figshare (2023)

Renata L. Muylaert David A. Wilkinson Tigga Kingston Paolo D’Odorico Maria Cristina Rulli

Hypothesized risk indicators informing the transmission scenarios, their rationale for inclusion, description and sources. Original rasters were warped to 0.25 decimal degrees and World Geodetic System (WGS 84). Complete data description available in Table S2. from Muylaert et al.

Spillover effect

Coronavirus

2019-20 coronavirus outbreak

10.6084/m9.figshare.23264678

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`Rings' of diffuse radio emission surrounding the Bullet cluster

arXiv (Cornell University) (2018)

Surajit Paul Abhirup Datta Siddharth Malu Prateek Gupta Reju Sam John

We present the discovery of ringlike diffuse radio emission structures in the peripheral regions of the Bullet cluster 1E 0657$-$55.8. Ring formations are spanning between 1--3 Mpc away from the center of the cluster, significantly further away from the two already reported relics. Integrated fluxes of four of the sub-regions in the inner `ring' from 4.5 to 10 GHz have also been reported. To understand the possible origin of these structures, here we present a maiden attempt of numerical modelling of a 3D and realistic `bullet' like event in a full cosmological ($Λ$CDM) environment with N-body plus hydrodynamics code. We report a simulated `bullet' found inside a (128 Mpc)$^3$ volume simulation with a speed of 2700 km s$^{-1}$, creating a high supersonic bow shock of Mach $M=3.5$ and a clear evidence of temporal separation of dark matter and baryons, assuring no challenge to $Λ$CDM cosmology from the bullet event as of now. We are also able to unveil the physics behind the formation of these observed multiple shock structures. Modelled radio emissions in our simulation support a complex combination of merger-associated processes that accelerates and re-accelerates fossil and cosmic-ray electrons. With a time evolution study and the computed radio emissions, we have shown that the ring like formation around the bullet is originated due to the interaction of the strong merger shocks with the accretion shocks at the periphery. The multiple shock structures observed are possibly originated from multiple mergers that have taken place at different times and much before the bullet event.

10.48550/arxiv.1804.02588

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Citations (2)

Study of Energy Distribution in Evolving Dynamical States of Galaxy Clusters and Groups

Shodhganga (2018)

Reju Sam John

Source

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Impact of Infectious Diseases on Wild Bovidae Populations in Thailand: Insights from Population Modelling and Disease Dynamics

bioRxiv (Cold Spring Harbor Laboratory) (2023)

Wantida Horpiencharoen Jonathan C. Marshall Renata L. Muylaert Reju Sam John David T. S. Hayman

Abstract The wildlife and livestock interface is vital for wildlife conservation and habitat management. Infectious diseases maintained by domestic species may impact threatened species such as Asian bovids, as they share natural resources and habitats. To predict the population impact of infectious diseases with different traits, we used stochastic mathematical models to simulate the population dynamics 100 times over 100 years for a model gaur ( Bos gaurus ) population with and without disease. We simulated repeated introductions from a reservoir, such as domestic cattle. We selected six bovine infectious diseases; anthrax, bovine tuberculosis, hemorrhagic septicaemia, lumpy skin disease, foot and mouth disease and brucellosis, all of which have caused outbreaks in wildlife populations. From a starting population of 300, the disease-free population increased by an average of 228% over 100 years. Brucellosis with frequency-dependent transmission showed the highest average population declines (−97%), with population extinction occurring 16% of the time. Foot and mouth disease with frequency-dependent transmission showed the lowest impact, with an average population increase of 200%. Overall, acute infections with very high or low fatality had the lowest impact, whereas chronic infections produced the greatest population decline. These results may help disease management and surveillance strategies support wildlife conservation.

Bovidae

10.1101/2023.08.29.554960

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Uniqueness of galaxy groups in the structural hierarchy from its radio signature

Surajit Paul Prateek Gupta Reju Sam John Venkat Punjabi

Galaxy groups are the intermediate structures in hierarchy of cosmic objects.Usually, galaxy clusters emerge out of mergers of groups of galaxies, but, no study confirms that groups are just the scaled down version of the clusters.In this work we have studied the thermal and non-thermal characteristics of galaxy groups from observational (SDSS catalogue) and theoretical (ENZO hydrodynamic simulations) point of view and compared them with the cluster properties.Our study shows that the mass scaling of both thermal and non-thermal properties of galaxy groups are deviating from cluster scale below 5 × 10 13 M .A prominent break in the scaling laws at 5 × 10 13 M has been observed in computed radio emission as well.We have also estimated the cosmic magnetic field using turbulent dynamo model for these objects and found to be at a level of sub-micro Gauss.Possible radio synchrotron emission from groups have been calculated using both Diffusive Shock Acceleration and Turbulent Re-acceleration models.It is observed that the total emission from some of the groups are much higher than what is expected from existing scaling laws.Such groups must be away from virialization and are at a highly dynamic state.Finally, we have predicted the expected radio flux from these highly active groups for possible detection by future telescopes (e.g.SKA, Upgraded GMRT etc.).

Signature (topology)

10.22323/1.267.0065

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Defining 'Galaxy Groups' As A Unique Objects In The Structural Hierarchy

Reju Sam John

`Galaxy groups' have hardly been realized as a separate class of objects with specific characteristics in the structural hierarchy of the universe. The presumption that the self-similarity of dark matter structures is a valid prescription for the baryonic universe also at all scales has rendered smaller structures undetectable by current observational facilities, leading to lesser dedicated studies on them. Some recent reports on deviation of $\rm{L_x}$-T scaling in groups from that of clusters have motivated us to study their physical properties in depth. In this article, we report the extensive study on physical properties of groups in comparison with clusters through cosmological hydrodynamic plus N-body simulations using ENZO 2.2 code. We have included cooling and heating physics and star formation feedback in the simulation. And produced a mock sample of 362 objects with mass ranging from $5\times10^{12}\; \rm{M_{\odot}}$ to 2.5$\times 10^{15}\; \rm{M_{\odot}}$. Strikingly, we have found that objects with a mass below $\sim$ $8\times 10^{13}\;\rm{M_{\odot}}$ do not follow any of the cluster self-similar laws in hydrostatics, not even in thermal and non-thermal regimes. Two distinct scaling laws are observed to be followed with breaks at $\sim$ $6-8\times 10^{13}\;\rm{M_{\odot}}$ for mass, $\sim$1 keV for temperature and $\sim$1 Mpc for radius. This places groups as a distinct entity in the hierarchical structures, well demarcated from clusters. This study reveals that groups are mostly far away from virialization, suggesting the need for formulating new models for deciphering their physical parameters. They are also shown to have high turbulence and more non-thermal energy stored, indicating better visibility in the non-thermal regime.

10.5281/zenodo.1009523

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Transmission models indicate Ebola virus persistence in non-human primate populations is unlikely

Journal of The Royal Society Interface (2022)

David T. S. Hayman Reju Sam John Pejman Rohani

Infectious diseases that kill their hosts may persist locally only if transmission is appropriately balanced by susceptible recruitment. Great apes die of Ebola virus disease (EVD) and have transmitted ebolaviruses to people. However, understanding the role that apes and other non-human primates play in maintaining ebolaviruses in Nature is hampered by a lack of data. Recent serological findings suggest that few non-human primates have antibodies to EVD-causing viruses throughout tropical Africa, suggesting low transmission rates and/or high EVD mortality (Ayouba A et al. 2019 J. Infect. Dis. 220 , 1599–1608 ( doi:10.1093/infdis/jiz006 ); Mombo IM et al. 2020 Viruses 12 , 1347 ( doi:10.3390/v12121347 )). Here, stochastic transmission models of EVD in non-human primates assuming high case-fatality probabilities and experimentally observed or field-observed parameters did not allow viral persistence, suggesting that non-human primate populations are highly unlikely to sustain EVD-causing infection for prolonged periods. Repeated introductions led to declining population sizes, similar to field observations of apes, but not viral persistence.

Persistence (discontinuity)

Ebolavirus

Case fatality rate

10.1098/rsif.2021.0638

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Citations (9)

Manufacturing cosmic rays in the evolving dynamical states of galaxy clusters

Monthly Notices of the Royal Astronomical Society (2019)

Reju Sam John Surajit Paul Luigi Iapichino K. Mannheim Harish Kumar

ABSTRACT Galaxy clusters are known to be reservoirs of cosmic rays (CRs), as inferred from theoretical calculations or detection of CR-derived observables. CR acceleration in clusters is mostly attributed to the dynamical activity that produces shocks. Shocks in clusters emerge out of merger or accretion, but which one is more effective in producing CRs? at which dynamical phase? and why? To this aim, we study the production or injection of CRs through shocks and its evolution in the galaxy clusters using cosmological simulations with the enzo code. Particle acceleration model considered here is primarily the Diffusive Shock Acceleration (DSA) of thermal particles, but we also report a tentative study with pre-existing CRs. Defining appropriate dynamical states using the concept of virialization, we studied a sample of merging and non-merging clusters. We report that the merger shocks (with Mach number $\mathcal {M}\sim 2-5$) are the most effective CR producers, while high-Mach peripheral shocks (i.e. $\mathcal {M}\gt 5$) are mainly responsible for the brightest phase of CR injection in clusters. Clusters once merged, permanently deviate from CR and X-ray mass scaling of non-merging systems, enabling us to use it as a tool to determine the state of merger. Through a temporal and spatial evolution study, we found a strong correlation between cluster merger dynamics and CR injection. We observed that the brightest phase of X-ray and CR injection from clusters occurs, respectively, at about 1.0 and 1.5 Gyr after every mergers, and CR injection peaks near to the cluster virial radius (i.e r200). Delayed CR injection peaks found in this study deserve further investigation for possible impact on the evolution of CR-derived observables from galaxy clusters.

10.1093/mnras/stz1785

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Citations (8)