1,313 research outputs found

    The structure of superheavy elements newly discovered in the reaction of 86^{86}Kr with 208^{208}Pb

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    The structure of superheavy elements newly discovered in the 208^{208}Pb(86^{86}Kr,n) reaction at Berkeley is systematically studied in the Relativistic Mean Field (RMF) approach. It is shown that various usually employed RMF forces, which give fair description of normal stable nuclei, give quite different predictions for superheavy elements. Among the effective forces we tested, TM1 is found to be the good candidate to describe superheavy elements. The binding energies of the 293^{293}118 nucleus and its α\alpha-decay daughter nuclei obtained using TM1 agree with those of FRDM within 2 MeV. Similar conclusion that TM1 is the good interaction is also drawn from the calculated binding energies for Pb isotopes with the Relativistic Continuum Hartree Bogoliubov (RCHB) theory. Using the pairing gaps obtained from RCHB, RMF calculations with pairing and deformation are carried out for the structure of superheavy elements. The binding energy, shape, single particle levels, and the Q values of the α\alpha-decay QαQ_{\alpha} are discussed, and it is shown that both pairing correlation and deformation are essential to properly understand the structure of superheavy elements. A good agreement is obtained with experimental data on QαQ_{\alpha}. %Especially, the atomic number %dependence of QαQ_{\alpha} %seems to match with the experimental observationComment: 19 pages, 5 figure

    Quantum tunneling in ^{277}112 and its alpha-decay chain

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    The α\alpha-decay half lives of nuclei in the decay from element 277112^{277}112 are calculated in a WKB framework using DDM3Y interaction and experimental Q-values. Theoretical estimation of half lives in the same quantum tunneling model, using Q-values from the mass formula of Muntian-Hofmann-Patyk-Sobiczewski, are also presented. Calculated results furnish corroborating evidence for the experimental findings at RIKEN and GSI. Certain discrepancies indicate necessity of a better mass formula. Further experimental data with higher statistics would also be useful.Comment: 10 page

    Gigantic hepatic amebic abscess presenting as acute abdomen: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Amebiasis is a parasitic disease caused by <it>Entamoeba histolytica</it>. It most commonly results in asymptomatic colonization of the gastrointestinal tract, but some patients develop intestinal invasive or extra-intestinal diseases. Liver abscess is the most common extra-intestinal manifestation. The large number of clinical presentations of amebic liver abscess makes the diagnosis very challenging in non-endemic countries. Late diagnosis of the amebic abscess may lead to perforation and amebic peritonitis, resulting in high mortality rates.</p> <p>Case presentation</p> <p>This report describes a 37-year-old white man, suffering from hepatitis B, with a gigantic amebic liver abscess presenting as an acute abdomen due to its rupture. Rapid deterioration of the patient's condition and acute abdomen led to an emergency operation. A large volume of free fluid together with debris was found at the moment of entry into the peritoneal cavity because of a rupture of the hepatic abscess at the position of the segment VIII. Surgical drainage of the hepatic abscess was performed; two wide drains were placed in the remaining hepatic cavities and one on the right hemithorax. The patient was hospitalized in the ICU for 14 days and for another 14 days in our department. The diagnosis of amebic abscess was made by the pathologists who identified <it>E. histolytica </it>in the debris.</p> <p>Conclusion</p> <p>Acute abdomen due to a ruptured amebic liver abscess is extremely rare in western countries where the parasite is not endemic. Prompt diagnosis and treatment are fundamental to preserving the patient's life since the mortality rates remain extremely high when untreated, even nowadays.</p

    Co3O4 Nanocrystals on Graphene as a Synergistic Catalyst for Oxygen Reduction Reaction

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    Catalysts for oxygen reduction and evolution reactions are at the heart of key renewable energy technologies including fuel cells and water splitting. Despite tremendous efforts, developing oxygen electrode catalysts with high activity at low costs remains a grand challenge. Here, we report a hybrid material of Co3O4 nanocrystals grown on reduced graphene oxide (GO) as a high-performance bi-functional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). While Co3O4 or graphene oxide alone has little catalytic activity, their hybrid exhibits an unexpected, surprisingly high ORR activity that is further enhanced by nitrogen-doping of graphene. The Co3O4/N-doped graphene hybrid exhibits similar catalytic activity but superior stability to Pt in alkaline solutions. The same hybrid is also highly active for OER, making it a high performance non-precious metal based bi-catalyst for both ORR and OER. The unusual catalytic activity arises from synergetic chemical coupling effects between Co3O4 and graphene.Comment: published in Nature Material

    Debris Disks: Probing Planet Formation

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    Debris disks are the dust disks found around ~20% of nearby main sequence stars in far-IR surveys. They can be considered as descendants of protoplanetary disks or components of planetary systems, providing valuable information on circumstellar disk evolution and the outcome of planet formation. The debris disk population can be explained by the steady collisional erosion of planetesimal belts; population models constrain where (10-100au) and in what quantity (>1Mearth) planetesimals (>10km in size) typically form in protoplanetary disks. Gas is now seen long into the debris disk phase. Some of this is secondary implying planetesimals have a Solar System comet-like composition, but some systems may retain primordial gas. Ongoing planet formation processes are invoked for some debris disks, such as the continued growth of dwarf planets in an unstirred disk, or the growth of terrestrial planets through giant impacts. Planets imprint structure on debris disks in many ways; images of gaps, clumps, warps, eccentricities and other disk asymmetries, are readily explained by planets at >>5au. Hot dust in the region planets are commonly found (<5au) is seen for a growing number of stars. This dust usually originates in an outer belt (e.g., from exocomets), although an asteroid belt or recent collision is sometimes inferred.Comment: Invited review, accepted for publication in the 'Handbook of Exoplanets', eds. H.J. Deeg and J.A. Belmonte, Springer (2018

    The DCDC2 deletion is not a risk factor for dyslexia

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    Dyslexia is a specific impairment in learning to read and has strong heritability. An intronic deletion within the DCDC2 gene, with ~8% frequency in European populations, is increasingly used as a marker for dyslexia in neuroimaging and behavioral studies. At a mechanistic level, this deletion has been proposed to influence sensory processing capacity, and in particular sensitivity to visual coherent motion. Our re-assessment of the literature, however, did not reveal strong support for a role of this specific deletion in dyslexia. We also analyzed data from five distinct cohorts, enriched for individuals with dyslexia, and did not identify any signal indicative of associations for the DCDC2 deletion with reading-related measures, including in a combined sample analysis (N=526). We believe we conducted the first replication analysis for a proposed deletion effect on visual motion perception and found no association (N=445 siblings). We also report that the DCDC2 deletion has a frequency of 37.6% in a cohort representative of the general population recruited in Hong Kong (N=220). This figure, together with a lack of association between the deletion and reading abilities in this cohort, indicates the low likelihood of a direct deletion effect on reading skills. Therefore, on the basis of multiple strands of evidence, we conclude that the DCDC2 deletion is not a strong risk factor for dyslexia. Our analyses and literature re-evaluation are important for interpreting current developments within multidisciplinary studies of dyslexia and, more generally, contribute to current discussions about the importance of reproducibility in science

    Surface TRAIL decoy receptor-4 expression is correlated with TRAIL resistance in MCF7 breast cancer cells

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    BACKGROUND: Tumor Necrosis Factor (TNF)-Related Apoptosis-Inducing Ligand (TRAIL) selectively induces apoptosis in cancer cells but not in normal cells. Despite this promising feature, TRAIL resistance observed in cancer cells seriously challenged the use of TRAIL as a death ligand in gene therapy. The current dispute concerns whether or not TRAIL receptor expression pattern is the primary determinant of TRAIL sensitivity in cancer cells. This study investigates TRAIL receptor expression pattern and its connection to TRAIL resistance in breast cancer cells. In addition, a DcR2 siRNA approach and a complementary gene therapy modality involving IKK inhibition (AdIKKβKA) were also tested to verify if these approaches could sensitize MCF7 breast cancer cells to adenovirus delivery of TRAIL (Ad5hTRAIL). METHODS: TRAIL sensitivity assays were conducted using Molecular Probe's Live/Dead Cellular Viability/Cytotoxicity Kit following the infection of breast cancer cells with Ad5hTRAIL. The molecular mechanism of TRAIL induced cell death under the setting of IKK inhibition was revealed by Annexin V binding. Novel quantitative Real Time RT-PCR and flow cytometry analysis were performed to disclose TRAIL receptor composition in breast cancer cells. RESULTS: MCF7 but not MDA-MB-231 breast cancer cells displayed strong resistance to adenovirus delivery of TRAIL. Only the combinatorial use of Ad5hTRAIL and AdIKKβKA infection sensitized MCF7 breast cancer cells to TRAIL induced cell death. Moreover, novel quantitative Real Time RT-PCR assays suggested that while the level of TRAIL Decoy Receptor-4 (TRAIL-R4) expression was the highest in MCF7 cells, it was the lowest TRAIL receptor expressed in MDA-MB-231 cells. In addition, conventional flow cytometry analysis demonstrated that TRAIL resistant MCF7 cells exhibited substantial levels of TRAIL-R4 expression but not TRAIL decoy receptor-3 (TRAIL-R3) on surface. On the contrary, TRAIL sensitive MDA-MB-231 cells displayed very low levels of surface TRAIL-R4 expression. Furthermore, a DcR2 siRNA approach lowered TRAIL-R4 expression on surface and this sensitized MCF7 cells to TRAIL. CONCLUSION: The expression of TRAIL-R4 decoy receptor appeared to be well correlated with TRAIL resistance encountered in breast cancer cells. Both adenovirus mediated IKKβKA expression and a DcR2 siRNA approach sensitized MCF7 breast cancer cells to TRAIL

    Dissection of genetic associations with language-related traits in population-based cohorts

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    Recent advances in the field of language-related disorders have led to the identification of candidate genes for specific language impairment (SLI) and dyslexia. Replication studies have been conducted in independent samples including population-based cohorts, which can be characterised for a large number of relevant cognitive measures. The availability of a wide range of phenotypes allows us to not only identify the most suitable traits for replication of genetic association but also to refine the associated cognitive trait. In addition, it is possible to test for pleiotropic effects across multiple phenotypes which could explain the extensive comorbidity observed across SLI, dyslexia and other neurodevelopmental disorders. The availability of genome-wide genotype data for such cohorts will facilitate this kind of analysis but important issues, such as multiple test corrections, have to be taken into account considering that small effect sizes are expected to underlie such associations

    Circumstellar discs: What will be next?

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    This prospective chapter gives our view on the evolution of the study of circumstellar discs within the next 20 years from both observational and theoretical sides. We first present the expected improvements in our knowledge of protoplanetary discs as for their masses, sizes, chemistry, the presence of planets as well as the evolutionary processes shaping these discs. We then explore the older debris disc stage and explain what will be learnt concerning their birth, the intrinsic links between these discs and planets, the hot dust and the gas detected around main sequence stars as well as discs around white dwarfs.Comment: invited review; comments welcome (32 pages
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