34 research outputs found
Energy-weighted density matrix embedding of open correlated chemical fragments
We present a multi-scale approach to efficiently embed an ab initio
correlated chemical fragment described by its energy-weighted density matrices,
and entangled with a wider mean-field many-electron system. This approach,
first presented in Phys. Rev. B, 98, 235132 (2018), is here extended to account
for realistic long-range interactions and broken symmetry states. The scheme
allows for a systematically improvable description in the range of correlated
fluctuations out of the fragment into the system, via a self-consistent
optimization of a coupled auxiliary mean-field system. It is discussed that the
method has rigorous limits equivalent to existing quantum embedding approaches
of both dynamical mean-field theory, as well as density matrix embedding
theory, to which this method is compared, and the importance of these
correlated fluctuations is demonstrated. We derive a self-consistent local
energy functional within the scheme, and demonstrate the approach for Hydrogen
rings, where quantitative accuracy is achieved despite only a single atom being
explicitly treated.Comment: 14 pages, 8 figure
The Bortoluzzi Mud Volcano (Ionian Sea, Italy) and its potential for tracking the seismic cycle of active faults
The Ionian Sea in southern Italy is at the center of active interaction and convergence between the Eurasian and African-Adriatic plates in the Mediterranean. This area is seismically active with instrumentally and/or historically recorded Mw > 7:0 earthquakes, and it is affected by recently discovered long strike-slip faults across the active Calabrian accretionary wedge. Many mud volcanoes occur on top of the wedge. A recently discovered one (called the Bortoluzzi Mud Volcano or BMV) was surveyed during the Seismofaults 2017 cruise (May 2017). High-resolution bathymetric backscatter surveys, seismic reflection profiles, geochemical and earthquake data, and a gravity core are used here to geologically, geochemically, and geophysically characterize this structure. The BMV is a circular feature ' 22 m high and ' 1100 m in diameter with steep slopes (up to a dip of 22). It sits atop the Calabrian accretionary wedge and a system of flower-like oblique-slip faults that are probably seismically active as demonstrated by earthquake hypocentral and focal data. Geochemistry of water samples from the seawater column on top of the BMV shows a significant contamination of the bottom waters from saline (evaporite-type) CH4-dominated crustal-derived fluids similar to the fluids collected from a mud volcano located on the Calabria mainland over the same accretionary wedge. These results attest to the occurrence of open crustal pathways for fluids through the BMV down to at least the Messinian evaporites at about-3000 m. This evidence is also substantiated by helium isotope ratios and by comparison and contrast with different geochemical data from three seawater columns located over other active faults in the Ionian Sea area. One conclusion is that the BMV may be useful for tracking the seismic cycle of active faults through geochemical monitoring. Due to the widespread diffusion of mud volcanoes in seismically active settings, this study contributes to indicating a future path for the use of mud volcanoes in the monitoring and mitigation of natural hazards
The marine activities performed within the TOMO-ETNA experiment
The TOMO-ETNA experiment was planned in order to obtain a detailed geological and structural model of the continental and oceanic crust beneath Mt. Etna volcano and northeastern Sicily up to the Aeolian Islands (southern Italy), by integrating data from active and passive refraction and reflection seismic methodologies, magnetic and gravity surveys. This paper focuses on the marine activities performed within the experiment, which have been carried out in the Ionian and Tyrrhenian Seas, during three multidisciplinary oceanographic cruises, involving three research vessels (\u201cSarmiento de Gamboa\u201d, \u201cGalatea\u201d and \u201cAegaeo\u201d) belonging to different countries and institutions. During the offshore surveys about 9700 air-gun shots were produced to achieve a high-resolution seismic tomography through the wide-angle seismic refraction method, covering a total of nearly 2650 km of shooting tracks. To register ground motion, 27 ocean bottom seismometers were deployed, extending the inland seismic permanent network of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and a temporary network installed for the experiment. A total of 1410 km of multi-channel seismic reflection profiles were acquired to image the subsurface of the area and to achieve a 2D velocity model for each profile. Multibeam sonar and sub bottom profiler data were also collected. Moreover, a total of 2020 km of magnetic and 680 km of gravity track lines were acquired to compile magnetic and gravity anomaly maps offshore Mt. Etna volcano. Here, high-resolution images of the seafloor, as well as sediment and rock samples, were also collected using a remotely operated vehicle
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
Cutaneous melioidosis: a review of the literature
BACKGROUND: Melioidosis is mainly observed in South-East Asia, where Burkholderia pseudomallei is endemic. Cutaneous melioidosis (CM) has rarely been described and in contrast to systemic forms, there are no therapeutic recommendations to guide management. METHODS: We reviewed the literature published before January 2018, evaluating: dermatological presentation, natural history, diagnostic methods, and treatment options. We also distinguish between primary and secondary CM in which the infection first started in the skin or came from an extracutaneous localization, respectively, and chronic CM when duration exceeded 2 months. The recommended treatment for systemic forms included ceftazidime or meropenem, followed by oral maintenance therapy with cotrimoxazole or amoxicillin - clavulanic acid. RESULTS: Forty-three cases were published in 38 articles. Twenty-nine patients (67.4%) were travelers, including 13 (44.8%) returning from Thailand. Thirty-eight patients (88%) had primary CM, including nine (29.9%) with chronic infection. All cases of secondary CM first presented with acute infection. The median incubation time was 3 weeks. The most common presentation was cutaneous abscesses (58%). The recommended treatment was administered in 62.7% cases with 37.2% for maintenance therapy. Sixteen patients (37.2%) underwent surgery. Death was reported in less than 5%. CONCLUSION: CM should be considered in travelers returning from or residents of endemic countries, particularly Thailand, presenting with cutaneous abscesses, cellulitis, or ulcerations. Surgery may be necessary in a substantial proportion of patients and follow-up of at least 1 year is essential. Therapeutic recommendations need to be established
Evaluation of minimal changes by ERP in chronic pancreatitis in comparison to PFT : follow up of 20 cases
Le diagnostic de pancréatite chronique est souvent difficile à établir en raison de la signification insuffisante des données morphologiques et des tests fonctionnels de routine. 20 patients porteurs d'altérations structurelles mineures sur pancréatogramme par PRE ont été à long terme soumis à des examens histopathologiques ou des contrôles pancréatographiques afin d'évaluer la valeur diagnostique des paramètres morphologiques mineurs observés. Les données pancréatographiques ont été comparées aux résultats du test perfusionnel à la Sécrétine-Caeruléine (TFP). La surveillance à long terme a montré dans 70 % des cas la valeur pronostique des « altérations mineures » comme indice de pancréatite chronique. Une corrélation entre pancréatographie et test à la Sécrétine-Caeruléine a été établie dans 75 % des cas