Intrinsic point defects and volume swelling in ZrSiO4 under irradiation

The effects of high concentration of point defects in crystalline ZrSiO4 as originated by exposure to radiation, have been simulated using first principles density functional calculations. Structural relaxation and vibrational studies were performed for a catalogue of intrinsic point defects, with different charge states and concentrations. The experimental evidence of a large anisotropic volume swelling in natural and artificially irradiated samples is used to select the subset of defects that give similar lattice swelling for the concentrations studied, namely interstitials of O and Si, and the anti-site Zr(Si), Calculated vibrational spectra for the interstitials show additional evidence for the presence of high concentrations of some of these defects in irradiated zircon.Comment: 9 pages, 7 (color) figure

Adolescent Sleep and Cellular Phone Use: Recent Trends and Implications for Research

Adolescent sleep needs range from 8.5–10 hours per night, with older adolescents requiring less sleep than younger adolescents. On average, however, American adolescents receive between 7.5–8.5 hours of sleep per night, with many sleeping fewer than 6.5 hours on school nights. Cellular phone use is emerging as an important factor that interferes with both sleep quality and quantity, particularly as smartphones become more widely available to teens. This review paper has three objectives. First, we will describe adolescent sleep patterns and the effects of sleep deprivation on adolescent physical and mental health. Second, we will describe current trends in technology use among adolescents, making associations to how technology impacts sleep. Lastly, we will discuss some of the methodological barriers of conducting sleep and technology research with adolescents and young adults and offer suggestions for overcoming those barriers. We will also discuss implications for healthcare providers

Literature Themes from Five Decades of Agricultural Communications Publications

The discipline of agricultural communications has been developing for nearly two centuries. As the discipline has adapted, professional organizations such as the American Association of `Agricultural College Editors (AAACE) and the Association for Communication Excellence in Agriculture, Natural Resources, and Life and Human Sciences (ACE) have published literature representative of the topics and issues that have impacted the discipline through magazines and journals such as the AAACE, ACE Quarterly, and the Journal of Applied Communications (JAC). The purpose of this study was to review the literature published in AAACE, ACE Quarterly, and JAC from 1968-2015 to identify primary and secondary literature themes. There were 13 emergent themes identified. The most prolific primary theme identified was Channel Development, Use or Research while the most prolific secondary theme identified was Educating Professionals. A count of the number of articles classified as “professional development” and “research” revealed a shift in the focus in the journal outlets. In earlier years, the discipline focused mainly on professional development articles (AAACE and ACE Quarterly), but transitioned almost completely to research (JAC). This research acknowledges that the discipline has experienced significant literary shifts and provides a recommendation for further research in audience analysis of the literature coming from the journals of the discipline

The projective consciousness model and phenomenal selfhood

We summarize our recently introduced Projective Consciousness Model (PCM) (Rudrauf et al., 2017) and relate it to outstanding conceptual issues in the theory of consciousness. The PCM combines a projective geometrical model of the perspectival phenomenological structure of the field of consciousness with a variational Free Energy minimization model of active inference, yielding an account of the cybernetic function of consciousness, viz., the modulation of the field's cognitive and affective dynamics for the effective control of embodied agents. The geometrical and active inference components are linked via the concept of projective transformation, which is crucial to understanding how conscious organisms integrate perception, emotion, memory, reasoning, and perspectival imagination in order to control behavior, enhance resilience, and optimize preference satisfaction. The PCM makes substantive empirical predictions and fits well into a (neuro)computationalist framework. It also helps us to account for aspects of subjective character that are sometimes ignored or conflated: pre-reflective self-consciousness, the first-person point of view, the sense of minenness or ownership, and social self-consciousness. We argue that the PCM, though still in development, offers us the most complete theory to date of what Thomas Metzinger has called "phenomenal selfhood.

Sample Science Input to Landing Site Selection for Mars 2020: An In-Situ Exploration and Sample Caching Rover

One of the Mars 2020 Rover mission’s main objectives is to collect samples of martian material and seal them in individual tubes for possible return by a later mission[1]. In order for the M2020 rover to have the highest chances of making a significant discovery from the diverse kinds of geological targets that Mars offers, it is crucial to select a landing site that would put the rover in proximity to these features. The M2020 landing site selection process is open to all [2]; however at this meeting we are seeking input from the sample science community into attributes of the landing site that should be prioritized. This paper seeks to foster broader intellectual inputs from the community, and outputs from this discussion will be provided to the M2020 landing site selection committee

High Burnup Effects Program A State-of-the-Technology Assessment

Various analytical models and empirical correlations describing the fission gas release phenomenon were examined. An evaluation was made of the current pertinent experimental data on the subject of high burnup fission gas release. Data reported by individual investigators were compared and evaluated in relation to their applicability to the content and scope of the High Burnup Effects Program. These evaluations then form the bases for defining the data needs, and the selection of variables to be studied in this program

Episodic photic zone euxinia in the northeastern Panthalassic Ocean during the end-Triassic extinction

Severe changes in ocean redox, nutrient cycling, and marine productivity accompanied most Phanerozoic mass extinctions. However, evidence for marine photic zone euxinia (PZE) as a globally important extinction mechanism for the end-Triassic extinction (ETE) is currently lacking. Fossil molecular (biomarker) and nitrogen isotopic records from a sedimentary sequence in western Canada provide the first conclusive evidence of PZE and disrupted biogeochemistry in neritic waters of the Panthalassic Ocean during the end Triassic. Increasing water-column stratification and deoxygenation across the ETE led to PZE in the Early Jurassic, paralleled by a perturbed nitrogen cycle and ecological turnovers among noncalcifying groups, including eukaryotic algae and prokaryotic plankton. If such conditions developed widely in the Panthalassic Ocean, PZE might have been a potent mechanism for the ETE.National Science Foundation (U.S.) (Grant EAR-1147402)Exobiology Program (U.S.) (Grants NNX09AM88G and NNA08CN84A)American Association of Petroleum Geologists (Grant-In-Aid)Mary-Hill and Bevan M. French Fund for Impact Geolog

Successful medical management of emphysematous gastritis with concomitant portal venous air: a case report

<p>Abstract</p> <p>Introduction</p> <p>The causes of diffuse abdominal pain following pelvic surgery are numerous. We present a rare case of acute abdominal pain in a woman in the post-partum period.</p> <p>Case presentation</p> <p>A 25-year-old Caucasian woman with neurofibromatosis type 1 presented to our hospital with diffuse abdominal pain immediately after a cesarean section. The patient was acutely ill and toxic with a fever of 38.8°C, a pulse of 120 beats per minute and a distended abdomen with absent bowel sounds. A computed tomography scan showed air in the wall of the stomach and portal venous system. The patient was successfully treated with intravenous antibiotics, bowel rest and total parenteral nutrition.</p> <p>Conclusion</p> <p>It is rare for a case of emphysematous gastritis associated with portal venous air to be treated successfully without surgery. To the best of our knowledge, to date there has been no reported association of emphysematous gastritis with neurofibromatosis.</p

The Xpc gene markedly affects cell survival in mouse bone marrow

The XPC protein (encoded by the xeroderma pigmentosum Xpc gene) is a key DNA damage recognition factor that is required for global genomic nucleotide excision repair (G-NER). In contrast to transcription-coupled nucleotide excision repair (TC-NER), XPC and G-NER have been reported to contribute only modestly to cell survival after DNA damage. Previous studies were conducted using fibroblasts of human or mouse origin. Since the advent of Xpc−/− mice, no study has focused on the bone marrow of these mice. We used carboplatin to induce DNA damage in Xpc−/− and strain-matched wild-type mice. Using several independent methods, Xpc−/− bone marrow was ∼10-fold more sensitive to carboplatin than the wild type. Importantly, 12/20 Xpc−/− mice died while 0/20 wild-type mice died. We conclude that G-NER, and XPC specifically, can contribute substantially to cell survival. The data are important in the context of cancer chemotherapy, where Xpc gene status and G-NER may be determinants of response to DNA-damaging agents including carboplatin. Additionally, altered cell cycles and altered DNA damage signalling may contribute to the cell survival end point

The imprint of atmospheric evolution in the D/H of Hesperian clay minerals on Mars

The deuterium to hydrogen (D/H) ratio in strongly bound water or hydroxyl groups in ancient martian clays retains the imprint of the water of formation of these minerals. Curiosity’s Sample Analysis at Mars (SAM) experiment measured thermally evolved water and hydrogen gas released between 550°C and 950°C from samples of Hesperian era Gale crater smectite to determine this isotope ratio. The D/H value is 3.0 (±0.2) times the ratio in Standard Mean Ocean Water (SMOW). The D/H ratio in this ~3 billion year old mudstone that is half that of the present martian atmosphere but substantially higher than that expected in very early Mars indicates an extended history of hydrogen escape and desiccation of the planet