Ploughing the deep sea floor

Bottom trawling is a non-selective commercial fishing technique whereby heavy nets and gear are pulled along the sea floor. The direct impact of this technique on fish populations and benthic communities has received much attention, but trawling can also modify the physical properties of seafloor sediments, water–sediment chemical exchanges and sediment fluxes. Most of the studies addressing the physical disturbances of trawl gear on the seabed have been undertaken in coastal and shelf environments, however, where the capacity of trawling to modify the seafloor morphology coexists with high-energy natural processes driving sediment erosion, transport and deposition. Here we show that on upper continental slopes, the reworking of the deep sea floor by trawling gradually modifies the shape of the submarine landscape over large spatial scales. We found that trawling-induced sediment displacement and removal from fishing grounds causes the morphology of the deep sea floor to become smoother over time, reducing its original complexity as shown by high-resolution seafloor relief maps. Our results suggest that in recent decades, following the industrialization of fishing fleets, bottom trawling has become an important driver of deep seascape evolution. Given the global dimension of this type of fishery, we anticipate that the morphology of the upper continental slope in many parts of the world’s oceans could be altered by intensive bottom trawling, producing comparable effects on the deep sea floor to those generated by agricultural ploughing on land.     

Serendipity and the Discovery of DNA

This paper presents the manner in which the DNA, the molecule of life, was discovered. Unlike what many people, even biologists, believe, it was Johannes Friedrich Miescher who originally discovered and isolated nuclein, currently known as DNA, in 1869, 75 years before Watson and Crick unveiled its structure. Also, in this paper we show, and above all demonstrate, the serendipity of this major discovery. Like many of his contemporaries, Miescher set out to discover how cells worked by means of studying and analysing their proteins. During this arduous task, he detected an unexpected substance of unpredicted properties. This new substance precipitated when he added acid to the solution and it dissolved again when adding alkali. Unexpectedly and by a mere fluke, Miescher was the first person to obtain a DNA precipitate. The paper then presents the term serendipity and discusses how it has influenced the discovery of other important scientific milestones. Finally, we address the question of whether serendipitous discoveries can be nurtured and what role the computer could play in this process.     

Soft System Dynamics Methodology in Action: A study of the Problem of Citizen Insecurity in an Argentinean Province

This paper illustrates an application of soft system dynamics methodology (SSDM). SSDM arose as a fusion of two well-known methodologies in the systems movement: system dynamics (SD) and soft systems methodology (SSM). SSDM includes 10 steps to orchestrate and implant change in social systems, based on a multimethodological and multiparadigmatic approach as an outcome of the combination of the mentioned methodologies. After a brief introduction, the paper starts by briefly explaining SSM and SD, their stages and their problematical issues as systemic methodologies, then goes on to explain SSDM, its philosophical roots and stages, ending with a comparison among the three. It then introduces the citizen insecurity problem in Argentina, specifically in Mendoza Province, where SSDM was applied to analyze this issue. The paper concludes with an explanation of the learning points that arose from the use of SSDM in this study and suggestions for further research on citizen security and SSDM.     

Mutations in genes encoding ribonuclease H2 subunits cause Aicardi-Goutières syndrome and mimic congenital viral brain infection

Aicardi-Goutières syndrome (AGS) is an autosomal recessive neurological disorder, the clinical and immunological features of which parallel those of congenital viral infection. Here we define the composition of the human ribonuclease H2 enzyme complex and show that AGS can result from mutations in the genes encoding any one of its three subunits. Our findings demonstrate a role for ribonuclease H in human neurological disease and suggest an unanticipated relationship between ribonuclease H2 and the antiviral immune response that warrants further investigation.