Self-organized criticality in deterministic systems with disorder

Using the Bak-Sneppen model of biological evolution as our paradigm, we investigate in which cases noise can be substituted with a deterministic signal without destroying Self-Organized Criticality (SOC). If the deterministic signal is chaotic the universality class is preserved; some non-universal features, such as the threshold, depend on the time correlation of the signal. We also show that, if the signal introduced is periodic, SOC is preserved but in a different universality class, as long as the spectrum of frequencies is broad enough.Comment: RevTex, 8 pages, 8 figure

Fluctuation-dissipation relationship in chaotic dynamics

We consider a general N-degree-of-freedom dissipative system which admits of chaotic behaviour. Based on a Fokker-Planck description associated with the dynamics we establish that the drift and the diffusion coefficients can be related through a set of stochastic parameters which characterize the steady state of the dynamical system in a way similar to fluctuation-dissipation relation in non-equilibrium statistical mechanics. The proposed relationship is verified by numerical experiments on a driven double well system.Comment: Revtex, 23 pages, 2 figure

Self-Organized Criticality Driven by Deterministic Rules

We have investigated the essential ingredients allowing a system to show Self Organized Criticality (SOC) in its collective behavior. Using the Bak-Sneppen model of biological evolution as our paradigm, we show that the random microscopic rules of update can be effectively substituted with a chaotic map without changing the universality class. Using periodic maps SOC is preserved, but in a different universality class, as long as the spectrum of frequencies is broad enough.Comment: 4 pages, RevTex (tar.gz), 4 eps-figures include

Recovery of a Medieval Brucella melitensis genome using shotgun metagenomics

ABSTRACT Shotgun metagenomics provides a powerful assumption-free approach to the recovery of pathogen genomes from contemporary and historical material. We sequenced the metagenome of a calcified nodule from the skeleton of a 14th-century middle-aged male excavated from the medieval Sardinian settlement of Geridu. We obtained 6.5-fold coverage of a Brucella melitensis genome. Sequence reads from this genome showed signatures typical of ancient or aged DNA. Despite the relatively low coverage, we were able to use information from single-nucleotide polymorphisms to place the medieval pathogen genome within a clade of B. melitensis strains that included the well-studied Ether strain and two other recent Italian isolates. We confirmed this placement using information from deletions and IS711 insertions. We conclude that metagenomics stands ready to document past and present infections, shedding light on the emergence, evolution, and spread of microbial pathogens

Distribution and paleoenvironmental framework of middle Miocene marine vertebrates along the western side of the lower Ica Valley (East Pisco Basin, Peru).

We report 130 vertebrate fossils preserved as bony elements and the co-occurring assemblage of fish teeth and spines from the lower strata of the Pisco Formation exposed along the western side of the lower Ica Valley (East Pisco Basin, Peru). Geological mapping at 1:10,000 scale reveals that all these fossils originate from the Langhian–Serravallian P0 allomember. In the study area, P0 is up to ∼40 m thick and features a sandy lower portion, reflecting shoreface deposition, that fines upwards into a package of offshore silts. Marine vertebrates only occur in the lower sandy layers and include whales, dolphins, reptiles, birds, and bony and cartilaginous fishes. The reconstructed paleoenvironment is consistent with a warm-water, marginal marine setting with a strong connection to the open ocean. This work helps to elucidate the rich yet still poorly understood middle Miocene portions of the Pisco Formation, and highlights the need to conserve this outstanding Fossil-Lagerstätte

Sclerosing bone dysplasia from 16th century Sardinia (Italy): a possible case of Camurati-Engelmann disease

The skeletal remains of a male aged 45–55 years displaying several bone anomalies were unearthed from the Alghero (Sardinia) plague cemetery ‘lo Quarter’, a burial site dating back to the 1582–1583 AD outbreak. The skeleton, whose stature is about 165 cm, presents a bilateral hyperostosis with increased diameter of the diaphyses of all the long bones of the upper and lower limbs; the metaphyses appear to be involved, while the epiphyses are spared. Marked thickening of the cranial vault is also evident. Radiological study showed irregular cortical thickening and massive endoperiosteal bone apposition; sclerotic changes are observed in the diaphysis of some metacarpals. Computed tomography (CT) cross sections of the long bones displayed a thickening of the cortical portion and endoperiosteal bone apposition. The individual was affected by a sclerosing bone dysplasia, a genetic disease characterized by increased bone density. In differential diagnosis, several sclerosing bone dysplasia, such as hyperostosis corticalis generalisata, craniodiaphyseal dysplasia, craniometadiaphyseal dysplasia, pachydermoperiostosis and Camurati–Engelmann disease, as well as other disorders characterized by sclerosing manifestations, such as Erdheim–Chester disease, mehloreostosis and skeletal fluorosis, need to be considered. The anomalies observed in skeleton 2179 fit with the features of Camurati–Engelmann disease, which is the most likely candidate for final diagnosis. It is highly challenging to evaluate how such a condition may have influenced the individual’s lifestyle in terms of development, mobility and quality of life. This individual was probably symptomatic and must have experienced common clinical symptoms, such as pain in the limbs and fatigability. However, the strong development of the muscular insertions and the degenerative changes in the upper limbs suggest that the mobility problems should not have prevented him from reaching a mature age and from performing essential daily activities. The presented case is the unique paleopathological evidence of Camurati–Engelmann disease so far diagnosed

Deciphering the tectono-stratigraphic evolution of the East Pisco Basin (southern Peru): new insights from the geological mapping of its central portion

The Cenozoic fill of the East Pisco Basin (EPB) preserves the sedimentary record of several episodes of deformation of the forearc crust along the Peruvian margin. The 1:50,000 scale geological map presented here covers an area of about 1,000 km2 lying astride the Ica River and, by establishing a first-order tectonostratigraphic frame for the exposed mid-Eocene–upper Miocene succession, contributes to our understanding of the timing and mode of basin filling and deformation. In the study area, deposition initiated onto the PaE0 nonconformity during the middle Eocene time and continued under an extensional regime until early Oligocene time, with a break in deposition recorded by the OE0 unconformity separating the Paracas and Otuma sequences (megasequence P). During this time interval, a single forearc Pisco Basin extended between an offshore outer forearc high and the Western Cordillera. An Oligocene relative sea-level fall, probably resulting from a combination of tectonic inversion and multiple events of eustatic lowstand, led the Pisco Basin to become subaerially exposed. Evidence for this phase of deformation is recorded by the conspicuous CE0 angular unconformity interposed between megasequences P and N. The oldest normal fault populations documented here consist of NNW- and ENE-trending faults largely predating the CE0 erosional hiatus. This widespread extensional faulting was accompanied by the exhumation of the Outer Shelf High-Coastal Cordillera, which segmented the earlier, Paleogene Pisco Basin into the present-day inner EPB and outer West Pisco Basin. Different tectonic processes have been invoked to explain the Oligocene uplift of the extensional Peruvian forearc basins and formation of the Outer Shelf High, including crustal thickening by underplating at an erosive margin or inversion by propagation of basement-rooted, westverging thrust faults. By earliest Miocene time, uplift ceased and subduction erosion and thinning of the overriding plate resulted in renewed subsidence, rise in relative sea level, and marine transgression over the CE0 unconformity with deposition of the lower Miocene Chilcatay and middle to upper Miocene Pisco composite sequences (megasequence N). The early Miocene phase of extension and associated subsidence was followed by a late Miocene contractional tectonic event, with shortening being accommodated by: (i) oblique-slip (reverse plus dextral) reactivation of inherited NE-trending extensional faults, and development of associated fault-parallel hanging-wall anticlines; and (ii) renewal tectonic uplift of the southwestern basin margin, as suggested by the fanning geometry of the northeast-dipping strata of the Pisco composite sequence and their progressive onlap on top of the basement towards the northeastern, internal margin of the basin

Enlarged vascular foramina and lytic lesions in vertebral bodies: a diagnostic dilemma

Among the skeletal material from the sites of Alghero, Mesumundu and Sant’Antioco di Bisarcio (Sassari, Sardinia) and dated back to the period comprises between the 13th and the late 16th century 5 subadult individuals aged between 5 and 15 years and a mature male showed peculiar osteolytic phenomena of the vertebral bodies. These lesions have the appearance of enlarged vascular foramina, affecting several vertebrae mainly of the thoracic and lumbar spine, sometimes with involvement of the sacrum; on the same vertebral body several lesions are generally visible. In the literature similar features have been attributed to brucellosis or tuberculosis. As for the Sardinian skeletal material, an imaging study on the vertebrae of the adult individual was carried out in order to evaluate the appearance of the lesions within the body. Computed Tomography evidenced internal irregular elongated cavitations, sometimes joined together; erosive rounded lesions, whose presence is not detectable externally, were also showed. The molecular analysis has so far been performed on the subadult from Sant’Antioco di Bisarcio, but at initial analysis the DNA resulted degraded. Therefore, the nature of these lesions remains unclear, as it is not sure if they should be referred to tuberculosis, brucellosis or other pathological conditions [hemolytic anemias (eg. Thalassemia), lymphomas, multiple myeloma and infection by Echinococcus]. Further molecular analyses will be carried out on the remains belonging to the other five individuals in an attempt to clarify the etiology of the above mentioned lesions

Facies analysis, stratigraphy and marine vertebrate assemblage of the lower Miocene Chilcatay Formation at Ullujaya (Pisco basin, Peru)

This paper is the first integrated account of the sedimentology, stratigraphy and vertebrate paleontology for the marine strata of the Chilcatay Formation exposed at Ullujaya, Pisco basin (southern Peru). An allostratigraphic framework for the investigated strata was established using geological mapping (1:4,000 scale) and conventional sedimentary facies analysis and resulted in recognition of two unconformity-bounded allomembers (designated Ct1 and Ct2 in ascending order). The chronostratigraphic framework is well constrained by integration of micropaleontological data and isotope geochronology and indicates deposition during the early Miocene. The marine vertebrate fossil assemblage is largely dominated by cetaceans (odontocetes), whereas isolated teeth and spines indicate a well-diversified elasmobranch assemblage. Our field surveys, conducted to evaluate the paleontological sensitivity of the investigated strata, indicate that vertebrate remains only came from a rather restricted stratigraphic interval of the Ct1 allomember and reveal the high potential for these sediments to yield abundant and scientifically significant fossil assemblages