846 research outputs found
Chandra Observation of the Interaction of the Radio Source and Cooling Core in Abell 2063
We present the results of a Chandra observation of the cooling core cluster
Abell 2063. Spectral analysis shows that there is cool gas (2 keV) associated
with the cluster core, which is more than a factor of 2 cooler than the outer
cluster gas (4.1 keV). There also is spectral evidence for a weak cooling flow,
Mdot ~ 20 Msun/yr. The cluster exhibits a complex structure in the center that
consists of several bright knots of emission, a depression in the emission to
the north of the center of the cluster, and a shell of emission surrounding it.
The depression in the X-ray emission is coincident with the position of the
north-eastern radio lobe of the radio source associated with the
cluster-central galaxy. The shell surrounding this region appears to be hotter,
which may be the result of a shock that has been driven into the gas by the
radio source. The power output of the radio source appears to be sufficient to
offset the cooling flow, and heating of the gas through shocks is a possible
explanation of how the energy transfer is established.Comment: Astrophysical Jounal, in press, 26 page with 9 figures, some in
color. Uses AASTEX late
SUCCESS FOR REMOVING OR BYPASSING INSTRUMENTS FRACTURED BEYOND THE ROOT CANAL CURVE – 45 CLINICAL CASES
The aim of the study is to compare success rates for ultrasonic removal or bypassing endodontic instruments, fractured below the curve of root canals.
Methods: 45 clinical cases – 30 MB and 5 ML root canals of mandibular molars, as well as 8 MB, 2 DB root canals of maxillary molars were selected from the authors’ private practice. 18 of the fragments are stainless steel files, 6 are rotary Ni-Ti files and 21 – lentulos. Fragments, to which visual access could be achieved by safe straightening of the root canal (26) were treated ultrasonically under dental microscope (OPMI Pico, Carl Zeiss) with magnification 10x and 16x. Bypass is chosen for fragments (19) without visibility.
Results: Ultrasonic group: 22 of 26 fragments (84,61%) were totally removed, and full working length was consequently reached in 69,23% of the cases (18 fragments). Four fragments (15,38%) separated additionally from the vibrations and could not be totally ultrasonically removed. Bypass group: only 7 of 19 fragments (36,84%) could be successfully bypassed.
Conclusions: Ultrasonic technique for broken instruments removal is significantly more successful than bypassing. Straight visible access to the fragment under dental microscope is crucial for successful fragments retrieval
EFFECTIVENESS IN THE CURVE OF EIGHT TYPES OF ENDOSONIC TIPS FOR BROKEN INSTRUMENTS REMOVAL.
Radiocarbon record of solar variability and Holocene climatic change in coastal southern California
EXTRACT (SEE PDF FOR FULL ABSTRACT):
Pollen analysis and 5 radiocarbon dates for a 687-cm core provide a detailed chronology of environmental change for San Joaquin Marsh at the head of Newport Bay, Orange County, California. Sediment deposition kept pace with sea level rise during the mid-Holocene, but after 4500 years BP, sea water regularly reached the coring site, and salt marsh was the local vegetation. Brief periods of dominance by fresh-water vegetation 3800, 2800, 2300 and after 560 years BP correlate global cooling events and (except the 3800-year BP event) with carbon-14 production anomalies. The coincidence of climate change and carbon-14 anomalies support a causal connection with solar variability, but regardless of the causal mechanism(s) the delta-carbon-14 curves provide a chronology for global, high-frequency climatic change comparable to that of Milankovitch cyclicity for longer time scales
Fate and transport of volatile organic compounds in glacial till and groundwater at an industrial site in Northern Ireland
Volatile organic compound (VOC) contamination of subsurface geological material and groundwater was discovered on the Nortel Monkstown industrial site, Belfast, Northern Ireland. The objectives of this study were to (1) investigate the characteristics of the geological material and its influences on contaminated groundwater flow across the site using borehole logs and hydrological evaluations, and (2) identify the contaminants and examine their distribution in the subsurface geological material and groundwater using chemical analysis. This report focuses on the eastern car park (ECP) which was a former storage area associated with trichloroethene (TCE) degreasing operations. This is where the greatest amount of volatile organic compounds (VOCs), particularly TCE, were detected. The study site is on a complex deposit of clayey glacial till with discontinuous coarser grained lenses, mainly silts, sands and gravel, which occur at 0.45-7.82 m below ground level (bgl). The lenses overall form an elongated formation that acts as a small unconfined shallow aquifer. There is a continuous low permeable stiff clayey till layer beneath the lenses that performs as an aquitard to the groundwater. Highest concentrations of VOCs, mainly TCE, in the geological material and groundwater are in these coarser lenses at similar to 4.5-7 m bgl. Highest TCE measurements at 390,000 mu g L-1 for groundwater and at 39,000 mu g kg(-1) at 5.7 m for geological material were in borehole GA19 in the coarse lens zone. It is assumed that TCE gained entrance to the subsurface near this borehole where the clayey till was thin to absent above coarse lenses which provided little retardation to the vertical migration of this dense non-aqueous phase liquid (DNAPL) into the groundwater. However, TCE is present in low concentrations in the geological material overlying the coarse lens zone. Additionally, VOCs appear to be associated with poorly drained layers and in peat < 3.0 m bgl in the ECP. Some indication of natural attenuation as VOCs degradation products vinyl chloride (VC) and dichloromethane (DCM) also occur on the site
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Relationships between changes in sustained fronto-striatal connectivity and positive affect with antidepressant treatment in major depression
Objective: Deficits in positive affect and their neural bases have been associated with major depression. However, whether reductions in positive affect result solely from an overall reduction in nucleus accumbens activity and fronto-striatal connectivity or the additional inability to sustain engagement of this network over time is unknown. The authors sought to determine whether treatment-induced changes in the ability to sustain nucleus accumbens activity and fronto-striatal connectivity during the regulation of positive affect are associated with gains in positive affect.
Method: Using fMRI, the authors assessed the ability to sustain activity in reward-related networks when attempting to increase positive emotion during per- formance of an emotion regulation para- digm in 21 depressed patients before and after 2 months of antidepressant treat- ment. Over the same interval, 14 healthy comparison subjects underwent scanning as well.
Results: After 2 months of treatment, self-reported positive affect increased. The patients who demonstrated the largest increases in sustained nucleus accumbens activity over the 2 months were those who demonstrated the largest increases in positive affect. In addition, the patients who demonstrated the largest increases in sustained fronto-striatal connectivity were also those who demonstrated the largest increases in positive affect when control- ling for negative affect. None of these associations were observed in healthy comparison subjects.
Conclusions: Treatment-induced change in the sustained engagement of fronto- striatal circuitry tracks the experience of positive emotion in daily life. Studies examining reduced positive affect in a va- riety of psychiatric disorders might benefit from examining the temporal dynamics of brain activity when attempting to under- stand changes in daily positive affect
Emerging Gene-Editing Modalities for Osteoarthritis
Osteoarthritis (OA) is a pathological degenerative condition of the joints that is widely prevalent worldwide, resulting in significant pain, disability, and impaired quality of life. The diverse etiology and pathogenesis of OA can explain the paucity of viable preventive and disease-modifying strategies to counter it. Advances in genome-editing techniques may improve disease-modifying solutions by addressing inherited predisposing risk factors and the activity of inflammatory modulators. Recent progress on technologies such as CRISPR/Cas9 and cell-based genome-editing therapies targeting the genetic and epigenetic alternations in OA offer promising avenues for early diagnosis and the development of personalized therapies. The purpose of this literature review was to concisely summarize the genome-editing options against chronic degenerative joint conditions such as OA with a focus on the more recently emerging modalities, especially CRISPR/Cas9. Future advancements in novel genome-editing therapies may improve the efficacy of such targeted treatments
Robust automatic hexahedral cartilage meshing framework enables population-based computational studies of the knee
Osteoarthritis of the knee is increasingly prevalent as our population ages, representing an increasing financial burden, and severely impacting quality of life. The invasiveness of in vivo procedures and the high cost of cadaveric studies has left computational tools uniquely suited to study knee biomechanics. Developments in deep learning have great potential for efficiently generating large-scale datasets to enable researchers to perform population-sized investigations, but the time and effort associated with producing robust hexahedral meshes has been a limiting factor in expanding finite element studies to encompass a population. Here we developed a fully automated pipeline capable of taking magnetic resonance knee images and producing a working finite element simulation. We trained an encoder-decoder convolutional neural network to perform semantic image segmentation on the Imorphics dataset provided through the Osteoarthritis Initiative. The Imorphics dataset contained 176 image sequences with varying levels of cartilage degradation. Starting from an open-source swept-extrusion meshing algorithm, we further developed this algorithm until it could produce high quality meshes for every sequence and we applied a template-mapping procedure to automatically place soft-tissue attachment points. The meshing algorithm produced simulation-ready meshes for all 176 sequences, regardless of the use of provided (manually reconstructed) or predicted (automatically generated) segmentation labels. The average time to mesh all bones and cartilage tissues was less than 2 min per knee on an AMD Ryzen 5600X processor, using a parallel pool of three workers for bone meshing, followed by a pool of four workers meshing the four cartilage tissues. Of the 176 sequences with provided segmentation labels, 86% of the resulting meshes completed a simulated flexion-extension activity. We used a reserved testing dataset of 28 sequences unseen during network training to produce simulations derived from predicted labels. We compared tibiofemoral contact mechanics between manual and automated reconstructions for the 24 pairs of successful finite element simulations from this set, resulting in mean root-mean-squared differences under 20% of their respective min-max norms. In combination with further advancements in deep learning, this framework represents a feasible pipeline to produce population sized finite element studies of the natural knee from subject-specific models
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