49 research outputs found
The seasonal cycle of ocean-atmosphere CO2 Flux in Ryder Bay, West Antarctic Peninsula
Approximately 15 million km2 of the Southern Ocean is seasonally ice covered, yet the processes affecting carbon cycling and gas exchange in this climatically important region remain inadequately understood. Here, 3 years of dissolved inorganic carbon (DIC) measurements and carbon dioxide (CO2) fluxes from Ryder Bay on the west Antarctic Peninsula (WAP) are presented. During spring and summer, primary production in the surface ocean promotes atmospheric CO2 uptake. In winter, higher DIC, caused by net heterotrophy and vertical mixing with Circumpolar Deep Water, results in outgassing of CO2 from the ocean. Ryder Bay is found to be a net sink of atmospheric CO2 of 0.59–0.94 mol C m−2 yr−1 (average of 3 years). Seasonal sea ice cover increases the net annual CO2 uptake, but its effect on gas exchange remains poorly constrained. A reduction in sea ice on the WAP shelf may reduce the strength of the oceanic CO2 sink in this region
Structural neural networks subserving oculomotor function in first-episode schizophrenia
BACKGROUND: Smooth pursuit and antisaccade abnormalities are well documented in schizophrenia, but their neuropathological correlates remain unclear.
METHODS: In this study, we used statistical parametric mapping to investigate the relationship between oculomotor abnormalities and brain structure in a sample of first-episode schizophrenia patients (n = 27). In addition to conventional volumetric magnetic resonance imaging, we also used magnetization transfer ratio, a technique that allows more precise tissue characterization.
RESULTS: We found that smooth pursuit abnormalities were associated with reduced magnetization transfer ratio in several regions, predominantly in the right prefrontal cortex. Antisaccade errors correlated with gray matter volume in the right medial superior frontal cortex as measured by conventional magnetic resonance imaging but not with magnetization transfer ratio.
CONCLUSIONS: These preliminary results demonstrate that specific structural abnormalities are associated with abnormal eye movements in schizophrenia
MicroRNA inhibition using antimiRs in acute human brain tissue sections
Antisense inhibition of microRNAs is an emerging preclinical approach to pharmacoresistant epilepsy. A leading candidate is an "antimiR" targeting microRNA-134 (ant-134), but testing to date has used rodent models. Here, we develop an antimiR testing platform in human brain tissue sections. Brain specimens were obtained from patients undergoing resective surgery to treat pharmacoresistant epilepsy. Neocortical specimens were submerged in modified artificial cerebrospinal fluid (ACSF) and dissected for clinical neuropathological examination, and unused material was transferred for sectioning. Individual sections were incubated in oxygenated ACSF, containing either ant-134 or a nontargeting control antimiR, for 24 h at room temperature. RNA integrity was assessed using BioAnalyzer processing, and individual miRNA levels were measured using quantitative reverse transcriptase polymerase chain reaction. Specimens transported in ACSF could be used for neuropathological diagnosis and had good RNA integrity. Ant-134 mediated a dose-dependent knockdown of miR-134, with approximately 75% reduction of miR-134 at 1 μmol L-1 and 90% reduction at 3 μmol L-1 . These doses did not have off-target effects on expression of a selection of three other miRNAs. This is the first demonstration of ant-134 effects in live human brain tissues. The findings lend further support to the preclinical development of a therapy that targets miR-134 and offer a flexible platform for the preclinical testing of antimiRs, and other antisense oligonucleotide therapeutics, in human brain
The Pan-STARRS Moving Object Processing System
We describe the Pan-STARRS Moving Object Processing System (MOPS), a modern
software package that produces automatic asteroid discoveries and
identifications from catalogs of transient detections from next-generation
astronomical survey telescopes. MOPS achieves > 99.5% efficiency in producing
orbits from a synthetic but realistic population of asteroids whose
measurements were simulated for a Pan-STARRS4-class telescope. Additionally,
using a non-physical grid population, we demonstrate that MOPS can detect
populations of currently unknown objects such as interstellar asteroids.
MOPS has been adapted successfully to the prototype Pan-STARRS1 telescope
despite differences in expected false detection rates, fill-factor loss and
relatively sparse observing cadence compared to a hypothetical Pan-STARRS4
telescope and survey. MOPS remains >99.5% efficient at detecting objects on a
single night but drops to 80% efficiency at producing orbits for objects
detected on multiple nights. This loss is primarily due to configurable MOPS
processing limits that are not yet tuned for the Pan-STARRS1 mission.
The core MOPS software package is the product of more than 15 person-years of
software development and incorporates countless additional years of effort in
third-party software to perform lower-level functions such as spatial searching
or orbit determination. We describe the high-level design of MOPS and essential
subcomponents, the suitability of MOPS for other survey programs, and suggest a
road map for future MOPS development.Comment: 57 Pages, 26 Figures, 13 Table
Thermal compensation of ultrasonic transmit and receive data for steel welded plates at the point of manufacture
On modern manufacturing production lines, Non-Destructive Testing (NDT) is frequently a bottleneck which could greatly be alleviated by integrating the inspection of components as they are manufactured. By moving inspection to the point of manufacture, greater economic and productivity benefits are realised in terms of reduced rework and schedule slippage, however, new technical challenges emerge. For welded components, high temperatures and the resulting thermal gradients, present challenges when performing ultrasonic inspection at the point of manufacture. The thermal gradients introduce positional misalignment due to “beam bending” effects arising from refraction as the material properties change with temperature. This paper presents for the first time, through simulation and practical experiments, a novel thermal compensation strategy to mitigate for thermal effects when performing ultrasonic inspection of welded components at the point of manufacture. To understand the thermal gradients experienced during standard Tungsten Inert Gas (TIG) welding, 3-dimensional thermal simulations were developed and experimentally-validated with an average error of 1.80%. The output from the thermal simulations in combination with material properties that vary over temperature, allowed for generalised time of flight maps to be created via the Multi-Stencils Fast Marching Method (MSFMM) and the ultrasonic data to be imaged by the Total Focusing Method (TFM). The thermal compensation strategy was initially proved on synthetically generated finite element Full Matrix Capture (FMC) datasets, and it was shown that reflector positional accuracy could be increased by ∼ 3 mm. Experimental results also showed marked improvements with reflector positional accuracy also being increased by ∼3 mm. Over both simulated and experimental datasets, the SNR was shown to be negligibly altered between uncompensated and compensated images. The results show how high-quality ultrasonic images can be generated in-process and help bring inspection closer to the point of manufacture
Development of a phased array ultrasonic system for residual stress measurement in welding and additive manufacturing
Residual Stress (RS) in engineering components can lead to unexpected and dangerous structural failures, and thus represent a significant challenge to quality assurance in both welding and metal additive manufacturing (AM) processes. The RS measurement using the ultrasonic method is based on the acoustoelasticity law, which states that the Time-of-Flight (ToF) of an ultrasonic wave is affected by the stress field. Longitudinal Critically Refracted (LCR) waves have the highest sensitivity to the stress in comparison with the other type of ultrasonic waves. However, they are also sensitive to the material texture which negatively affects the accuracy of the RS measurement. In this paper, a Phased Array Ultrasonic Testing (PAUT) system, rather than the single element transducers which are traditionally used in the LCR stress measurement technique, is innovatively used to enhance the accuracy of RS measurement. An experimental setup is developed that uses the PAUT to measure the ToFs in the weld, where the maximum amount of tensile RS is expected, and in the parent material, stress-free part. The ToF variations are then interpreted and analyzed to qualify the RS in the weld. The same measurement process is repeated for the Wire Arc Additive Manufacture (WAAM) components. Based on the results, some variations between different acoustic paths are measured which prove that the effect of the residual stress on the ultrasonic wave is detectable using the PAUT system
Adaptive Evolution of the Myo6 Gene in Old World Fruit Bats (Family: Pteropodidae)
PMCID: PMC3631194This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Model-assisted ultrasonic calibration using intentionally embedded defects for in-process weld inspection
Automated in-process Non-Destructive Testing (NDT) systems are rapidly gaining traction within the manufacturing industry as they reduce manufacturing time and costs. When considering calibration and verification of such systems, creating defects of known geometry and nature during the deposition of a weld can: (I) help examine the capability of the automated system to detect and characterise defects, (II) be used to form a database of signals associated with different defect types to train intelligent defect classification algorithms, and (III) act as a basis for in-process gain calibration during weld inspection at high temperatures, where the ultrasound beam can be skewed as a result of velocity gradients. In view of this, this paper investigates two unique methodologies for introducing: (a) lack of fusion weld defects by embedding tungsten in the weld and (b) creating artificial weld cracks by quenching to imitate the real cracking scenarios. According to the results of Phased Array Ultrasound Testing (PAUT) inspections, the methodologies used for embedding the artificial defects were successful. The validity of inspections was also verified by extracting micrographs from the defective sections of the welds, and model-based simulations were carried out to gain a better understanding of the wave propagation path and interaction with the generated defects
A study of human resource competencies required to implement community rehabilitation in less resourced settings.
BACKGROUND: It is estimated that over one billion persons worldwide have some form of disability. However, there is lack of knowledge and prioritisation of how to serve the needs and provide opportunities for people with disabilities. The community-based rehabilitation (CBR) guidelines, with sufficient and sustained support, can assist in providing access to rehabilitation services, especially in less resourced settings with low resources for rehabilitation. In line with strengthening the implementation of the health-related CBR guidelines, this study aimed to determine what workforce characteristics at the community level enable quality rehabilitation services, with a focus primarily on less resourced settings. METHODOLOGY: This was a two-phase review study using (1) a relevant literature review informed by realist synthesis methodology and (2) Delphi survey of the opinions of relevant stakeholders regarding the findings of the review. It focused on individuals (health professionals, lay health workers, community rehabilitation workers) providing services for persons with disabilities in less resourced settings. RESULTS: Thirty-three articles were included in this review. Three Delphi iterations with 19 participants were completed. Taken together, these produced 33 recommendations for developing health-related rehabilitation services. Several general principles for configuring the community rehabilitation workforce emerged: community-based initiatives can allow services to reach more vulnerable populations; the need for supportive and structured supervision at the facility level; core skills likely include case management, social protection, monitoring and record keeping, counselling skills and mechanisms for referral; community ownership; training in CBR matrix and advocacy; a tiered/teamwork system of service delivery; and training should take a rights-based approach, include practical components, and involve persons with disabilities in the delivery and planning. CONCLUSION: This research can contribute to implementing the WHO guidelines on the interaction between the health sector and CBR, particularly in the context of the Framework for Action for Strengthening Health Systems, in which human resources is one of six components. Realist syntheses can provide policy makers with detailed and practical information regarding complex health interventions, which may be valuable when planning and implementing programmes