Cosmic voids in modified gravity scenarios

Modified gravity (MG) theories aim to reproduce the observed acceleration of the Universe by reducing the dark sector while simultaneously recovering General Relativity (GR) within dense environments. Void studies appear to be a suitable scenario to search for imprints of alternative gravity models on cosmological scales. Voids cover an interesting range of density scales where screening mechanisms fade out, which reaches from a density contrast $\delta \approx -1$ close to their centers to $\delta \approx 0$ close to their boundaries. We present an analysis of the level of distinction between GR and two modified gravity theories, the Hu-Sawicki $f(R)$ and the symmetron theory. This study relies on the abundance, linear bias, and density profile of voids detected in n-body cosmological simulations. We define voids as connected regions made up of the union of spheres with a {\it \textup{mean}} density given by $\overline\rho_v=0.2\,\overline\rho_m$, but disconnected from any other voids. We find that the height of void walls is considerably affected by the gravitational theory, such that it increases for stronger gravity modifications. Finally, we show that at the level of dark matter n-body simulations, our constraints allow us to distinguish between GR and MG models with $|f_{R0}| > 10^{-6}$ and $z_{SSB} > 1$. Differences of best-fit values for MG parameters that are derived independently from multiple void probes may indicate an incorrect MG model. This serves as an important consistency check.Comment: 15 pages, 12 figure

Acute Kidney Injury in Poor Countries Should No Longer Be a Death Sentence: The ISN '0 by 25' Project.

Acute kidney injury (AKI) is a common disorder throughout the world that is associated with severe morbidity, mortality and cost. Although deaths due to AKI occur in both high- and low- and middle-income countries (LMIC), the majority of avoidable deaths occur in LMIC nations. If managed adequately and in a timely fashion, the majority of these cases of AKI are preventable, treatable and often reversible with simple measures. AKI also has a major economic impact on healthcare expenditure. This is particularly true in poor countries where AKI especially impacts young productive people, imposing severe penury on their families. The International Society of Nephrology (ISN) has launched a long-term program, the '0 by 25' project, which advocates that zero people should die of untreated AKI in the poorest part of Africa, Asia and Latin America by 2025. The mission is to eventually lessen the high burden in terms of deaths consequent to this disorder in resource-poor regions worldwide. This is a challenging but potentially feasible and productive initiative that requires a broad vision about how the public and private sectors can work in partnership with the governments of the LMIC countries and leading nongovernmental organizations operating locally, to ensure sustainability of the 0 by 25 program and save many lives