Quantifying compressible groundwater storage by combining cross-hole seismic surveys and head response to atmospheric tides

Groundwater specific storage varies by orders of magnitude, is difficult to quantify, and prone to significant uncertainty. Estimating specific storage using aquifer testing is hampered by the nonuniqueness in the inversion of head data and the assumptions of the underlying conceptual model. We revisit confined poroelastic theory and reveal that the uniaxial specific storage can be calculated mainly from undrained poroelastic properties, namely, uniaxial bulk modulus, loading efficiency, and the Biot-Willis coefficient. In addition, literature estimates of the solid grain compressibility enables quantification of subsurface poroelastic parameters using field techniques such as cross-hole seismic surveys and loading efficiency from the groundwater responses to atmospheric tides. We quantify and compare specific storage depth profiles for two field sites, one with deep aeolian sands and another with smectitic clays. Our new results require bulk density and agree well when compared to previous approaches that rely on porosity estimates. While water in clays responds to stress, detailed sediment characterization from a core illustrates that the majority of water is adsorbed onto minerals leaving only a small fraction free to drain. This, in conjunction with a thorough analysis using our new method, demonstrates that specific storage has a physical upper limit of (Formula presented.) m−1. Consequently, if larger values are derived using aquifer hydraulic testing, then the conceptual model that has been used needs reappraisal. Our method can be used to improve confined groundwater storage estimates and refine the conceptual models used to interpret hydraulic aquifer tests

Back-action Evading Measurements of Nanomechanical Motion

When performing continuous measurements of position with sensitivity approaching quantum mechanical limits, one must confront the fundamental effects of detector back-action. Back-action forces are responsible for the ultimate limit on continuous position detection, can also be harnessed to cool the observed structure, and are expected to generate quantum entanglement. Back-action can also be evaded, allowing measurements with sensitivities that exceed the standard quantum limit, and potentially allowing for the generation of quantum squeezed states. We realize a device based on the parametric coupling between an ultra-low dissipation nanomechanical resonator and a microwave resonator. Here we demonstrate back-action evading (BAE) detection of a single quadrature of motion with sensitivity 4 times the quantum zero-point motion, back-action cooling of the mechanical resonator to n = 12 quanta, and a parametric mechanical pre-amplification effect which is harnessed to achieve position resolution a factor 1.3 times quantum zero-point motion.Comment: 19 pages (double-spaced) including 4 figures and reference

Significant loss of mitochondrial diversity within the last century due to extinction of peripheral populations in eastern gorillas

Species and populations are disappearing at an alarming rate as a direct result of human activities. Loss of genetic diversity associated with population decline directly impacts species' long-term survival. Therefore, preserving genetic diversity is of considerable conservation importance. However, to assist in conservation efforts, it is important to understand how genetic diversity is spatially distributed and how it changes due to anthropogenic pressures. In this study, we use historical museum and modern faecal samples of two critically endangered eastern gorilla taxa, Grauer's (Gorilla beringei graueri) and mountain gorillas (Gorilla beringei beringei), to directly infer temporal changes in genetic diversity within the last century. Using over 100 complete mitochondrial genomes, we observe a significant decline in haplotype and nucleotide diversity in Grauer's gorillas. By including historical samples from now extinct populations we show that this decline can be attributed to the loss of peripheral populations rather than a decrease in genetic diversity within the core range of the species. By directly quantifying genetic changes in the recent past, our study shows that human activities have severely impacted eastern gorilla genetic diversity within only four to five generations. This rapid loss calls for dedicated conservation actions, which should include preservation of the remaining peripheral populations.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Extreme Conservation Leads to Recovery of the Virunga Mountain Gorillas

As wildlife populations are declining, conservationists are under increasing pressure to measure the effectiveness of different management strategies. Conventional conservation measures such as law enforcement and community development projects are typically designed to minimize negative human influences upon a species and its ecosystem. In contrast, we define “extreme” conservation as efforts targeted to deliberately increase positive human influences, including veterinary care and close monitoring of individual animals. Here we compare the impact of both conservation approaches upon the population growth rate of the critically endangered Virunga mountain gorillas (Gorilla beringei beringei), which increased by 50% since their nadir in 1981, from approximately 250 to nearly 400 gorillas. Using demographic data from 1967–2008, we show an annual decline of 0.7%±0.059% for unhabituated gorillas that received intensive levels of conventional conservation approaches, versus an increase 4.1%±0.088% for habituated gorillas that also received extreme conservation measures. Each group of habituated gorillas is now continuously guarded by a separate team of field staff during daylight hours and receives veterinary treatment for snares, respiratory disease, and other life-threatening conditions. These results suggest that conventional conservation efforts prevented a severe decline of the overall population, but additional extreme measures were needed to achieve positive growth. Demographic stochasticity and socioecological factors had minimal impact on variability in the growth rates. Veterinary interventions could account for up to 40% of the difference in growth rates between habituated versus unhabituated gorillas, with the remaining difference likely arising from greater protection against poachers. Thus, by increasing protection and facilitating veterinary treatment, the daily monitoring of each habituated group contributed to most of the difference in growth rates. Our results argue for wider consideration of extreme measures and offer a startling view of the enormous resources that may be needed to conserve some endangered species

A manually annotated Actinidia chinensis var. chinensis (kiwifruit) genome highlights the challenges associated with draft genomes and gene prediction in plants

Most published genome sequences are drafts, and most are dominated by computational gene prediction. Draft genomes typically incorporate considerable sequence data that are not assigned to chromosomes, and predicted genes without quality confidence measures. The current Actinidia chinensis (kiwifruit) 'Hongyang' draft genome has 164\ua0Mb of sequences unassigned to pseudo-chromosomes, and omissions have been identified in the gene models