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Stone was a critical resource for prehistoric hunter-gatherers. Archaeologists, therefore, have long argued that these groups would actively have sought out stone of ‘high quality’. Although the defining of quality can be a complicated endeavour, researchers in recent years have suggested that stone with fewer impurities would be preferred for tool production, as it can be worked and used in a more controllable way. The present study shows that prehistoric hunter-gatherers at the Holocene site of Welling, in Ohio, USA, continuously selected the ‘purest’ stone for over 9000 years.
To identify the intracochlear electrode position in cochlear implant recipients and determine the correlation to speech perception for two peri-modiolar electrode arrays.
Post-operative cone-beam computed tomography images of 92 adult recipients of the ‘CI512’ electrode and 18 adult recipients of the ‘CI532’ electrode were analysed. Phonemes scores were recorded pre-implantation, and at 3 and 12 months post-implantation.
All CI532 electrodes were wholly within scala tympani. Of the 79 CI512 electrodes intended to be in scala tympani, 58 (73 per cent) were in scala tympani, 14 (17 per cent) were translocated and 7 (9 per cent) were wholly in scala vestibuli. Thirteen CI512 electrodes were deliberately inserted into scala vestibuli. Speech perception scores for post-lingual recipients were higher in the scala tympani group (69.1 per cent) compared with the scala vestibuli (54.2 per cent) and translocation (50 per cent) groups (p < 0.05). Electrode location outside of scala tympani independently resulted in a 10.5 per cent decrease in phoneme scores.
Cone-beam computed tomography was valuable for demonstrating electrode position. The rate of scala tympani insertion was higher in CI532 than in CI512 electrodes. Scala vestibuli insertion and translocation were associated with poorer speech perception outcomes.
Objectives: Obstructive sleep apnea (OSA) is associated with cognitive impairment but the relationships between specific biomarkers and neurocognitive domains remain unclear. The present study examined the influence of common health comorbidities on these relationships. Adults with suspected OSA (N=60; 53% male; M age=52 years; SD=14) underwent neuropsychological evaluation before baseline polysomnography (PSG). Apneic syndrome severity, hypoxic strain, and sleep architecture disturbance were assessed through PSG. Methods: Depression (Center for Epidemiological Studies Depression Scale, CESD), pain, and medical comorbidity (Charlson Comorbidity Index) were measured via questionnaires. Processing speed, attention, vigilance, memory, executive functioning, and motor dexterity were evaluated with cognitive testing. A winnowing approach identified 9 potential moderation models comprised of a correlated PSG variable, comorbid health factor, and cognitive performance. Results: Regression analyses identified one significant moderation model: average blood oxygen saturation (AVO2) and depression predicting recall memory, accounting for 31% of the performance variance, p<.001. Depression was a significant predictor of recall memory, p<.001, but AVO2 was not a significant predictor. The interaction between depression and AVO2 was significant, accounting for an additional 10% of the variance, p<.001. The relationship between low AVO2 and low recall memory performance emerged when depression severity ratings approached a previously established clinical cutoff score (CESD=16). Conclusions: This study examined sleep biomarkers with specific neurocognitive functions among individuals with suspected OSA. Findings revealed that depression burden uniquely influence this pathophysiological relationship, which may aid clinical management. (JINS, 2018, 28, 864–875)
To investigate the effectiveness and usability of automated procedural guidance during virtual temporal bone surgery.
Two randomised controlled trials were performed to evaluate the effectiveness, for medical students, of two presentation modalities of automated real-time procedural guidance in virtual reality simulation: full and step-by-step visual presentation of drillable areas. Presentation modality effectiveness was determined through a comparison of participants’ dissection quality, evaluated by a blinded otologist, using a validated assessment scale.
While the provision of automated guidance on procedure improved performance (full presentation, p = 0.03; step-by-step presentation, p < 0.001), usage of the two different presentation modalities was vastly different (full presentation, 3.73 per cent; step-by-step presentation, 60.40 per cent).
Automated procedural guidance in virtual temporal bone surgery is effective in improving trainee performance. Step-by-step presentation of procedural guidance was engaging, and therefore more likely to be used by the participants.
The distribution of molecular markers in sediments provides a reservoir of unique information concerning biogeochemical processes in the geological past, and how these processes respond to environmental change. However, sedimentary systems themselves are biologically dynamic and these markers, and their precursors, have been subjected to bacterial degradation and modification. Recent research indicates that key changes in sedimented organic matter take place during the earliest stages of sediment burial and diagenesis where bacterial activity is also intense. Hence, effective interpretation of the distribution of biomarkers from deep sediment layers and sedimentary rocks requires knowledge of the rates and processes of bacterial decomposition under a range of environmental conditions.
Algae are important primary producers in the marine environment. The prymnesiophyte alga Emiliania huxleyi was selected as a subject for study as it is a source of long chain ketones which are geochemically important biomarkers. The ratio of the ketones C37:2 to C37:3 is temperature sensitive and has been used as a palaeotemperature indicator (UK37).
Preliminary sediment slurry incubations were carried out to optimize experimental design (concentration of decay organism, concentration of sediment in slurry, ability to obtain defined microbial environments over long term incubations, aerobic and anaerobic), and quantitative analytical scheme (extraction and separation technique, type and concentration of internal standards). Subsequent experiments on aerobic bacterial degradation of E. huxleyi demonstrated rapid increase in bacterial activity and biomass. This was accompanied by major changes in lipid classes. The dominant aliphatic hydrocarbons, three isomers of nC31:2, were rapidly degraded and completely removed by 78 days. In contrast, in preliminary anaerobic incubations, the same compounds remained unchanged. By 78 days a significant reduction in the total algal sterols was accompanied by a small increase in total stanols; hence the cholestanol/cholesterol ratio increased markedly. The abundance of the long chain unsaturated ketone C37:3 decreased relative to C37:2 resulting in an increase in the UK37 ratio. The reasons for these changes are unclear. However, they indicate that bacterial degradation may have to be taken into account in the interpretation of UK37 ratios in terms of paleotemperatures.
Further experiments are in progress to clarify the interpretation of these results and provide information on the more recalcitrant biomarkers.
A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities.
X-ray emission from > 100 pre-main sequence (PMS) stars in the Orion star-forming complex is studied in a 20-ks observation by XMM-Newton. No relation between the ratio of X-ray and bolometric luminosities, LX/Lbol, and rotation period or Rossby number is exhibited, though the action of a solar-like dynamo is not excluded because all stars would appear to be in the “saturated regime” of such a dynamo. Low-mass stars showing a strong U — V excess have lower median X-ray luminosity, suggesting that accretion suppresses magnetic activity.
We have compiled a catalogue of H ii regions detected with the Murchison Widefield Array between 72 and 231 MHz. The multiple frequency bands provided by the Murchison Widefield Array allow us identify the characteristic spectrum generated by the thermal Bremsstrahlung process in H ii regions. We detect 306 H ii regions between 260° < l < 340° and report on the positions, sizes, peak, integrated flux density, and spectral indices of these H ii regions. By identifying the point at which H ii regions transition from the optically thin to thick regime, we derive the physical properties including the electron density, ionised gas mass, and ionising photon flux, towards 61 H ii regions. This catalogue of H ii regions represents the most extensive and uniform low frequency survey of H ii regions in the Galaxy to date.
We review the first six years of radio observations of Supernova 1987A. The evolution can be divided into two phases: the initial radio outburst which lasted a few weeks, and the period from mid-1990 to the present, during which the radio emission has steadily increased. Both phases can be explained by a small fraction (0.1-0.5%) of the post-shock thermal energy being converted to energy in relativistic particles and magnetic fields, which give rise to synchrotron radiation. The optical depths, densities and density profiles for the pre-shocked circumstellar material are somewhat different for the two phases, but consistent with models of the density structure of the material within the circumstellar ring. New high-resolution radio observations show that the SN shock front is already at about three-quarters of the radius of the circumstellar ring, and that there exists a bright equatorial component of emission aligned with this ring which is probably due to a polar density gradient in the ‘hourglass’ structure.
We compare first-order (refractive) ionospheric effects seen by the MWA with the ionosphere as inferred from GPS data. The first-order ionosphere manifests itself as a bulk position shift of the observed sources across an MWA field of view. These effects can be computed from global ionosphere maps provided by GPS analysis centres, namely the CODE. However, for precision radio astronomy applications, data from local GPS networks needs to be incorporated into ionospheric modelling. For GPS observations, the ionospheric parameters are biased by GPS receiver instrument delays, among other effects, also known as receiver DCBs. The receiver DCBs need to be estimated for any non-CODE GPS station used for ionosphere modelling. In this work, single GPS station-based ionospheric modelling is performed at a time resolution of 10 min. Also the receiver DCBs are estimated for selected Geoscience Australia GPS receivers, located at Murchison Radio Observatory, Yarragadee, Mount Magnet and Wiluna. The ionospheric gradients estimated from GPS are compared with that inferred from MWA. The ionospheric gradients at all the GPS stations show a correlation with the gradients observed with the MWA. The ionosphere estimates obtained using GPS measurements show promise in terms of providing calibration information for the MWA.
GLEAM, the GaLactic and Extragalactic All-sky MWA survey, is a survey of the entire radio sky south of declination + 25° at frequencies between 72 and 231 MHz, made with the MWA using a drift scan method that makes efficient use of the MWA’s very large field-of-view. We present the observation details, imaging strategies, and theoretical sensitivity for GLEAM. The survey ran for two years, the first year using 40-kHz frequency resolution and 0.5-s time resolution; the second year using 10-kHz frequency resolution and 2 s time resolution. The resulting image resolution and sensitivity depends on observing frequency, sky pointing, and image weighting scheme. At 154 MHz, the image resolution is approximately 2.5 × 2.2/cos (δ + 26.7°) arcmin with sensitivity to structures up to ~ 10° in angular size. We provide tables to calculate the expected thermal noise for GLEAM mosaics depending on pointing and frequency and discuss limitations to achieving theoretical noise in Stokes I images. We discuss challenges, and their solutions, that arise for GLEAM including ionospheric effects on source positions and linearly polarised emission, and the instrumental polarisation effects inherent to the MWA’s primary beam.
The Murchison Widefield Array is a Square Kilometre Array Precursor. The telescope is located at the Murchison Radio–astronomy Observatory in Western Australia. The MWA consists of 4 096 dipoles arranged into 128 dual polarisation aperture arrays forming a connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to the correlation task is employed, with some processing stages being performed by bespoke hardware, based on Field Programmable Gate Arrays, and others by Graphics Processing Units housed in general purpose rack mounted servers. The correlation capability required is approximately 8 tera floating point operations per second. The MWA has commenced operations and the correlator is generating 8.3 TB day−1 of correlation products, that are subsequently transferred 700 km from the MRO to Perth (WA) in real-time for storage and offline processing. In this paper, we outline the correlator design, signal path, and processing elements and present the data format for the internal and external interfaces.
The Murchison Widefield Array is a new low-frequency interferometric radio telescope built in Western Australia at one of the locations of the future Square Kilometre Array. We describe the automated radio-frequency interference detection strategy implemented for the Murchison Widefield Array, which is based on the aoflagger platform, and present 72–231 MHz radio-frequency interference statistics from 10 observing nights. Radio-frequency interference detection removes 1.1% of the data. Radio-frequency interference from digital TV is observed 3% of the time due to occasional ionospheric or atmospheric propagation. After radio-frequency interference detection and excision, almost all data can be calibrated and imaged without further radio-frequency interference mitigation efforts, including observations within the FM and digital TV bands. The results are compared to a previously published Low-Frequency Array radio-frequency interference survey. The remote location of the Murchison Widefield Array results in a substantially cleaner radio-frequency interference environment compared to Low-Frequency Array’s radio environment, but adequate detection of radio-frequency interference is still required before data can be analysed. We include specific recommendations designed to make the Square Kilometre Array more robust to radio-frequency interference, including: the availability of sufficient computing power for radio-frequency interference detection; accounting for radio-frequency interference in the receiver design; a smooth band-pass response; and the capability of radio-frequency interference detection at high time and frequency resolution (second and kHz-scale respectively).
The science cases for incorporating high time resolution capabilities into modern radio telescopes are as numerous as they are compelling. Science targets range from exotic sources such as pulsars, to our Sun, to recently detected possible extragalactic bursts of radio emission, the so-called fast radio bursts (FRBs). Originally conceived purely as an imaging telescope, the initial design of the Murchison Widefield Array (MWA) did not include the ability to access high time and frequency resolution voltage data. However, the flexibility of the MWA’s software correlator allowed an off-the-shelf solution for adding this capability. This paper describes the system that records the 100 μs and 10 kHz resolution voltage data from the MWA. Example science applications, where this capability is critical, are presented, as well as accompanying commissioning results from this mode to demonstrate verification.
To determine whether there is a difference in antibody titers and functionality after receipt of the influenza vaccine for obese versus nonobese healthcare workers (HCW).
Prospective observational study.
Tertiary medical center.
Baseline influenza antibody titers for obese and nonobese HCW were recorded during the hospital’s 2011 annual influenza vaccination day and follow-up antibody titers were measured 4 weeks later. Antibodies were measured using the hemagglutination inhibition assay and functionality was measured using the micro-neutralization method.
Of 200 initial HCWs, 190 completed the study (97 obese and 93 nonobese). Seroprotection after immunization was not significantly different for nonobese compared with obese HCW for each strain (influenza A [H1N1], 99% and 99%; influenza A [H3N2], 100% and 99%; and influenza B, 67% and 71%, respectively)
All geometric mean titers measured by micro-neutralization showed statistically significant increases in activity. In comparison, there was no difference in the 4-fold increase in H1N1 or B titers. There was a significant difference in the 4-fold increase of H3N2 titers between the nonobese and obese HCWs (82/93 [88%] vs 64/97 [66%], P=.003)
In an ad hoc analysis we found that obese HCWs had a statistically greater number of 4-fold decreases in titers with H1N1 and H3N2.
There was no significant difference in protection from influenza between obese and nonobese HCWs after immunization.