364 research outputs found

    Scale and numerical modeling to determine operating points of a non-clogging Vortecone filter in mining operation

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    Numerical and scale modeling studies of Vortecone, a pressure-driven wet-scrubber device for the efficient capture of over-sprayed paint in the automobile industry, are presented. In this manuscript, Vortecone was tested for removing dust particles from underground mining operations. The pressures required to operate Vortecone and the airflow rates through the Vortecone are the two most important factors for mine ventilation systems. This study used dry, no-particle conditions to obtain relationship between these two parameters and then designed a Vortecone filter ventilation system for mining operations. Commercial software, SC/Flow, was used to generate the CFD model with unstructured meshes and a series of numerical calculations were accomplished. Included in these were calculation of a 1/3rd scale model of Vortecone along with experimentation that was accomplished to validate the numerical predictions. The experiments were conducted to measure pressure drops for known airflow velocities at critical points within Vortecone. The scale model experimental results agreed very well with the CFD numerical calculations. For scaling the performance of the 1/3rd scale model to full scale, the scaling laws were developed using the law approach; they are discussed along with the feasibility of the Vortecone filter system for underground mining operations

    Oligomerization and the Affinity of Maize Phosphoenolpyruvate Carboxylase for Its Substrate

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    Theoretical study of peculiarities of unstable longitudinal shear crack growth in sub-Rayleigh and supershear regimes

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    In the paper we present the results of the theoretical study of some fundamental aspects of mode II crack propagation in conventional sub-Rayleigh regime and transition to intersonic regime. It is shown that development of a sub-Rayleigh shear crack is determined in many respects by elastic vortex traveling ahead of the crack tip at a shear wave velocity. Formation of such a vortex helps to better understand the well-known phenomenon of acceleration of a shear crack towards the longitudinal wave velocity. Simulation results have shown that due to self-similarity of shear crack propagation the conditions of sub-Rayleigh to intersonic transition depend on dimensionless material and crack parameters. Two key dimensionless parameters are proposed

    Imatinib in combination with hydroxyurea versus hydroxyurea alone as oral therapy in patients with progressive pretreated glioblastoma resistant to standard dose temozolomide

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    A randomized, multicenter, open-label, phase 3 study of patients with progressive, recurrent glioblastoma multiforme (GBM) for whom front-line therapy had failed was conducted. This study was designed to determine whether combination therapy with imatinib and hydroxyurea (HU) has superior antitumor activity compared with HU monotherapy in the treatment of recurrent GBM. The target population consisted of patients with confirmed recurrent GBM and an Eastern Cooperative Oncology Group performance status of 0-2 who had completed previous treatment comprising surgical resection, irradiation therapy, and first-line chemotherapy (preferably temozolomide (TMZ) containing regimen) and who have progressed despite treatment. If first-line chemotherapy did not contain TMZ, a second completed chemotherapy was acceptable. The primary efficacy parameter was progression-free survival (PFS). The primary comparison of combination therapy versus monotherapy for PFS was not significant (adjusted P = 0.56). The hazard ratio (HR) (adjusted HR = 0.93) was not clinically relevant. The median PFS for the combination arm was low at 6 weeks and similar to the median PFS in the monotherapy arm (6 weeks). The 6-month PFS for the two treatment groups was very similar (5% in the combination arm vs. 7% in the monotherapy arm). No clinically meaningful differences were found between the two treatment arms, and the primary study end point was not met. Among the patients receiving imatinib, no adverse events were reported that were either previously unknown or unexpected as a consequence of the disease

    Spatial and temporal scales of coral reef fish ecological research and management: a systematic map protocol

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    This is the final version. Available on open access from BMC via the DOI in this recordBackground Coral reefs are rapidly changing in response to local and global stressors. Research to better understand and inform the management of these stressors is burgeoning. However, in situ studies of coral reef ecology are constrained by complex logistics and limited resources. Many reef studies are also hampered by the scale-dependent nature of ecological patterns, and inferences made on causal relationships within coral reef systems are limited by the scales of observation. This is because most socio-ecological studies are conducted at scales relevant to the phenomenon of interest. However, management often occurs across a significantly broader, often geopolitical, range of scales. While there is a critical need for incisive coral reef management actions at relevant spatial and temporal scales, it remains unclear to what extent the scales of empirical study overlap with the scales at which management inferences and recommendations are made. This systematic map protocol will evaluate this potential scale mismatch with the goal of raising awareness about the significance of effectively addressing and reporting the scales at which researchers collect data and make assumptions. Methods We will use the Collaboration for Environmental Evidence (CEE) systematic mapping guidelines to identify relevant studies using a framework-based synthesis to summarise the spatial and temporal scales of coral reef fish ecology research and the scales at which management inferences or recommendations are made. Using tested predefined terms, we will search for relevant published academic and grey literature, including bibliographic databases, web-based search engines, and organisational websites. Inclusion criteria for the evidence map are empirical studies that focus on coral reef fish ecological organisation and processes, those informing management interventions and policy decisions, and management documents that cite coral reef research for management decision-making. Study results will be displayed graphically using data matrices and heat maps. This is the first attempt to systematically assess and compare the scales of socio-ecological research conducted on coral reef systems with their management.NOAA Coral Reef Conservation Progra

    Effects of Transcranial Direct Current Stimulation on Episodic Memory Related to Emotional Visual Stimuli

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    The present study investigated emotional memory following bilateral transcranial electrical stimulation (direct current of 1 mA, for 20 minutes) over fronto-temporal cortical areas of healthy participants during the encoding of images that differed in affective arousal and valence. The main result was a significant interaction between the side of anodal stimulation and image emotional valence. Specifically, right anodal/left cathodal stimulation selectively facilitated the recall of pleasant images with respect to both unpleasant and neutral images whereas left anodal/right cathodal stimulation selectively facilitated the recall of unpleasant images with respect to both pleasant and neutral images. From a theoretical perspective, this double dissociation between the side of anodal stimulation and the advantage in the memory performance for a specific type of stimulus depending on its pleasantness supported the specific-valence hypothesis of emotional processes, which assumes a specialization of the right hemisphere in processing unpleasant stimuli and a specialization of the left hemisphere in processing pleasant stimuli. From a methodological point of view, first we found tDCS effects strictly dependent on the stimulus category, and second a pattern of results in line with an interfering and inhibitory account of anodal stimulation on memory performance. These findings need to be carefully considered in applied contexts, such as the rehabilitation of altered emotional processing or eye-witness memory, and deserve to be further investigated in order to understand their underlying mechanisms of action

    National strategy for palliative care of severely ill and dying people and their relatives in pandemics (PallPan) in Germany - study protocol of a mixed-methods project

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    BACKGROUND In the SARS-CoV-2 pandemic, general and specialist Palliative Care (PC) plays an essential role in health care, contributing to symptom control, psycho-social support, and providing support in complex decision making. Numbers of COVID-19 related deaths have recently increased demanding more palliative care input. Also, the pandemic impacts on palliative care for non-COVID-19 patients. Strategies on the care for seriously ill and dying people in pandemic times are lacking. Therefore, the program 'Palliative care in Pandemics' (PallPan) aims to develop and consent a national pandemic plan for the care of seriously ill and dying adults and their informal carers in pandemics including (a) guidance for generalist and specialist palliative care of patients with and without SARS-CoV-2 infections on the micro, meso and macro level, (b) collection and development of information material for an online platform, and (c) identification of variables and research questions on palliative care in pandemics for the national pandemic cohort network (NAPKON). METHODS Mixed-methods project including ten work packages conducting (online) surveys and qualitative interviews to explore and describe i) experiences and burden of patients (with/without SARS-CoV-2 infection) and their relatives, ii) experiences, challenges and potential solutions of health care professionals, stakeholders and decision makers during the SARS-CoV-2 pandemic. The work package results inform the development of a consensus-based guidance. In addition, best practice examples and relevant literature will be collected and variables for data collection identified. DISCUSSION For a future \textquotedblpandemic preparedness\textquotedbl national and international recommendations and concepts for the~care of severely ill and dying people are necessary considering both generalist and specialist palliative care in the home care and inpatient setting

    Insights into the abundance and diversity of abyssal megafauna in a polymetallic-nodule region in the eastern Clarion-Clipperton Zone

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    There is growing interest in mining polymetallic nodules in the abyssal Clarion-Clipperton Zone (CCZ) in the Pacific. Nonetheless, benthic communities in this region remain poorly known. The ABYSSLINE Project is conducting benthic biological baseline surveys for the UK Seabed Resources Ltd. exploration contract area (UK-1) in the CCZ. Using a Remotely Operated Vehicle, we surveyed megafauna at four sites within a 900 km2 stratum in the UK-1 contract area, and at a site ~250 km east of the UK-1 area, allowing us to make the first estimates of abundance and diversity. We distinguished 170 morphotypes within the UK-1 contract area but species-richness estimators suggest this could be as high as 229. Megafaunal abundance averaged 1.48 ind. m−2. Seven of 12 collected metazoan species were new to science, and four belonged to new genera. Approximately half of the morphotypes occurred only on polymetallic nodules. There were weak, but statistically significant, positive correlations between megafaunal and nodule abundance. Eastern-CCZ megafaunal diversity is high relative to two abyssal datasets from other regions, however comparisons with CCZ and DISCOL datasets are problematic given the lack of standardised methods and taxonomy. We postulate that CCZ megafaunal diversity is driven in part by habitat heterogeneity.This open access work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0
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