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  • 1
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    Ernietta from the late Edicaran Nama Group, Namibia (2016)
    Paleontological Society
    Details
    Publication Date: 2016-11-11
    Description: Ernietta plateauensis Pflug, 1966 is the type species of the Erniettomorpha, an extinct clade of Ediacaran life. It was likely a gregarious, partially infaunal organism. Despite its ecological and taxonomic significance, there has not been an in-depth systematic description in the literature since the original description fell out of use. A newly discovered field site on Farm Aar in southern Namibia has yielded dozens of specimens buried in original life position. Mudstone and sandstone features associated with the fossils indicate that organisms were buried while still exposed to the water column rather than deposited in a flow event. Ernietta plateauensis was a sac-shaped erniettomorph with a body wall constructed from a double layer of tubes. It possessed an equatorial seam lying perpendicular to the tubes. The body is asymmetrical on either side of this seam. The tubes change direction along the body length and appear to be constricted together in the dorsal part of the organism.
    Print ISSN: 0022-3360
    Electronic ISSN: 1937-2337
    Topics: Geosciences
    Published by Paleontological Society
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  • 2
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    Mechanical properties of natural radiation-damaged titanite and temperature-induced structural reorganization: A nanoindentation and Raman spectroscopic study (2016)
    Mineralogical Society of America
    Details
    Publication Date: 2016-02-03
    Description: This study provides new insights into the relation between thermally induced structural reorganization and the macroscopic mechanical properties of radiation-damaged titanite. The natural sample contains ca. 30% amorphous fraction. Low-temperature annealing affects only slightly the sample stiffness and leads to a softening resulting from the defect annihilation in crystalline regions. In the high-temperature annealing regime, amorphous domains recrystallize and this leads to further recovery of defects, reduction of interfaces, grain growth, and, in general, an increase in the long-range order. The thermally induced recrystallization is accompanied by massive dehydration leading to considerable stiffening and hardening. This interpretation of the recrystallization process in titanite based on the correlation of new results from nanoindentation and Raman-spectroscopic measurements complementing previous investigations using thermogravimetric and gas analyses by Hawthorne et al. (1991) and infrared spectroscopy by Zhang et al. (2001) . The new data combined with previous work leads to a detailed description of the annealing behavior of a radiation-damaged titanite, which is a complicated process that includes dehydration and atomic-scale structural reorganization. To minimize the influence of surface phenomena on the hardness measurements, the so-called "true" hardness was used instead of the standard hardness calculation ( Oliver and Pharr 1992 ). A comparison shows that the Oliver and Pharr method clearly underestimates the hardness.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 3
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    Exocometary gas in the HD 181327 debris ring (2016)
    Oxford University Press
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    Publication Date: 2016-06-17
    Description: An increasing number of observations have shown that gaseous debris discs are not an exception. However, until now, we only knew of cases around A stars. Here we present the first detection of 12 CO (2–1) disc emission around an F star, HD 181327, obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) observations at 1.3 mm. The continuum and CO emission are resolved into an axisymmetric disc with ring-like morphology. Using a Markov chain Monte Carlo method coupled with radiative transfer calculations, we study the dust and CO mass distribution. We find the dust is distributed in a ring with a radius of 86.0 ± 0.4 au and a radial width of 23.2 ± 1.0 au. At this frequency, the ring radius is smaller than in the optical, revealing grain size segregation expected due to radiation pressure. We also report on the detection of low-level continuum emission beyond the main ring out to ~200 au. We model the CO emission in the non-local thermodynamic equilibrium regime and we find that the CO is co-located with the dust, with a total CO gas mass ranging between 1.2  x 10 –6  M and 2.9 x 10 –6 M , depending on the gas kinetic temperature and collisional partners densities. The CO densities and location suggest a secondary origin, i.e. released from icy planetesimals in the ring. We derive a CO+CO 2 cometary composition that is consistent with Solar system comets. Due to the low gas densities, it is unlikely that the gas is shaping the dust distribution.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 4
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    Right and Left Ventricular Function and Mass in Male Elite Master Athletes: A Controlled Contrast-Enhanced Cardiovascular Magnetic Resonance Study [Exercise Physiology] (2016)
    American Heart Association (AHA)
    Details
    Publication Date: 2016-05-17
    Description: Background— It is under debate whether the cumulative effects of intensive endurance exercise induce chronic cardiac damage, mainly involving the right heart. The aim of this study was to examine the cardiac structure and function in long-term elite master endurance athletes with special focus on the right ventricle by contrast-enhanced cardiovascular magnetic resonance. Methods and Results— Thirty-three healthy white competitive elite male master endurance athletes (age range, 30–60 years) with a training history of 29±8 years, and 33 white control subjects pair-matched for age, height, and weight underwent cardiopulmonary exercise testing, echocardiography including tissue-Doppler imaging and speckle tracking, and cardiovascular magnetic resonance. Indexed left ventricular mass and right ventricular mass (left ventricular mass/body surface area, 96±13 and 62±10 g/m 2 ; P 〈0.001; right ventricular mass/body surface area, 36±7 and 24±5 g/m 2 ; P 〈0.001) and indexed left ventricular end-diastolic volume and right ventricular end-diastolic volume (left ventricular end-diastolic volume/body surface area, 104±13 and 69±18 mL/m 2 ; P 〈0.001; right ventricular end-diastolic volume/body surface area, 110±22 and 66±16 mL/m 2 ; P 〈0.001) were significantly increased in athletes in comparison with control subjects. Right ventricular ejection fraction did not differ between athletes and control subjects (52±8 and 54±6%; P =0.26). Pathological late enhancement was detected in 1 athlete. No correlations were found for left ventricular and right ventricular volumes and ejection fraction with N-terminal pro-brain natriuretic peptide, and high-sensitive troponin was negative in all subjects. Conclusions— Based on our results, chronic right ventricular damage in elite endurance master athletes with lifelong high training volumes seems to be unlikely. Thus, the hypothesis of an exercise-induced arrhythmogenic right ventricular cardiomyopathy has to be questioned.
    Keywords: Exercise, Cardiomyopathy, Magnetic Resonance Imaging (MRI)
    Electronic ISSN: 1524-4539
    Topics: Medicine
    Published by American Heart Association (AHA)
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  • 5
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    Antimicrobial and Virulence-Modulating Effects of Clove Essential Oil on the Foodborne Pathogen Campylobacter jejuni [Physiology] (2016)
    The American Society for Microbiology (ASM)
    Details
    Publication Date: 2016-10-08
    Description: Our study investigated the antimicrobial action of clove ( Syzygium aromaticum ) essential oil (EO) on the zoonotic pathogen Campylobacter jejuni . After confirming the clove essential oil's general antibacterial effect, we analyzed the reference strain Campylobacter jejuni NCTC 11168. Phenotypic, proteomic, and transcriptomic methods were used to reveal changes in cell morphology and functions when exposed to sublethal concentrations of clove EO. The normally curved cells showed markedly straightened and shrunken morphology on the scanning electron micrographs as a result of stress. Although, oxidative stress, as a generally accepted response to essential oils, was also present, the dominance of a general stress response was demonstrated by reverse transcription-PCR (RT-PCR). The results of RT-PCR and two-dimensional (2D) PAGE revealed that clove oil perturbs the expression of virulence-associated genes taking part in the synthesis of flagella, PEB1, PEB4, lipopolysaccharide (LPS), and serine protease. Loss of motility was also detected by a phenotypic test. Bioautographic analysis revealed that besides its major component, eugenol, at least four other spots of clove EO possessed bactericidal activity against C. jejuni . Our findings show that clove EO has a marked antibacterial and potential virulence-modulating effect on C. jejuni . IMPORTANCE This study demonstrates that the components of clove essential oil influence not only the expression of general stress genes but also the expression of virulence-associated genes. Based on this finding, alternative strategies can be worked on to control this important foodborne pathogen.
    Print ISSN: 0099-2240
    Electronic ISSN: 1098-5336
    Topics: Biology
    Published by The American Society for Microbiology (ASM)
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  • 6
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    Viscosity measurements of metallic melts using the oscillating drop technique (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-06-15
    Description: By means of benchmarking reduced gravity experiments, we have verified the measured viscosity of binary Zr-Ni glass forming liquids utilizing the oscillating drop technique combined with ground-based electrostatic levitation (ESL). Reliable viscosity data can be obtained as long as internal viscous damping of a single oscillation mode of a levitated drop dominates external perturbations. This can be verified by the absence of a sample mass dependence of the results. Hence, ESL is an excellent tool for studying the viscosity of metallic glass forming melts in the range of about 10–250 mPa s, with sample masses below 100 mg. To this end, we show that, for binary Zr-Ni melts, the viscosity is qualitatively controlled by the packing density.
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 7
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    Non-heme iron enzymes in nogalamycin biosynthesis [Chemistry] (2016)
    National Academy of Sciences
    Details
    Publication Date: 2016-05-12
    Description: Nogalamycin, an aromatic polyketide displaying high cytotoxicity, has a unique structure, with one of the carbohydrate units covalently attached to the aglycone via an additional carbon–carbon bond. The underlying chemistry, which implies a particularly challenging reaction requiring activation of an aliphatic carbon atom, has remained enigmatic. Here, we show that...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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