Differential Gradient Research Articles

A Wet Gas Metering System Based on the Extended-Throat Venturi Tube.

Although the use of a classical Venturi tube for wet gas metering has been extensively studied in the literature, the use of an extended-throat Venturi (ETV) tube has rarely been reported since its first proposal by J. R. Fincke in 1999. The structure of an ETV is very simple, but due to the complexity of multiphase flow, its theoretical model has not been fully established yet. Therefore, in this paper theoretical models have been developed for the convergent and throat sections of an ETV, and the gradients of front and rear differential pressures are derived analytically. Several flowrate algorithms have been proposed and compared with the existing ones. Among them, the iteration algorithm is found to be the best. A reasonable explanation is provided for its performance. The relationship between the differential pressure gradient and the flowrate relative error is also studied, such that the relative error distributions varying with ETV measured flowrates can be derived. The gas flowrate error of ETV increases with the liquid content whilst the liquid flowrate error of ETV decreases with the liquid content, and the relative errors of liquid flowrate are generally 2 to 3 times larger than that of the gas flowrate. Finally, the ETV tends to be more accurate than the classical Venturi tube. The ETV can be designed more compact under the same signal intensity due to its significantly higher velocity in the throat section.

DGT: A contribution-aware differential gradient transmission mechanism for distributed machine learning

Distributed machine learning is a mainstream system to learn insights for analytics and intelligence services of many fronts (e.g., health, streaming and business) from their massive operational data. In such a system, multiple workers train over subsets of data and collaboratively derive a global prediction/inference model by iteratively synchronizing their local learning results, e.g., the model gradients, which in turn generates heavy and bursty traffic and results in high communication overhead in cluster networks. Such communication overhead has became the main bottleneck that limits the efficiency of training machine learning models distributedly. In this paper, our key observation is that local gradients learned by workers may have different contributions to global model convergence and executing differential transmission for different gradients can reduce the communication overhead and improve training efficiency. However, existing gradient transmission mechanisms treat all gradients the same, which may lead to long training time.Motivated by our observations, we propose Differential Gradient Transmission (DGT), a contribution-aware differential gradient transmission mechanism for efficient distributed learning, which transfers gradients with different transmission quality according to their contributions. In addition to designing a general architecture of DGT, we have proposed a novel algorithm and a novel protocol to facilitate fast model training. Experiments on a cluster with 6 GTX 1080TI GPUs and 1Gbps network show that DGT decreases the model training time by 19.4% on GoogleNet, 34.4% on AlexNet and 36.5% on VGG-11 compared to default gradient transmission on MXNET. Its acceleration is better than the other two related transmission solutions. Besides, DGT works well with different datasets (Fashion-MNIST, Cifar10), different data distributions (IID, non-IID) and different training algorithms (BSP, FedAVG).

Optimisation and comparison of orthogonal methods for separation and characterisation of extracellular vesicles to investigate how representative infant milk formula is of milk

Many infants are fed infant milk formula (IMF). However, IMF production from skim milk (SM) involves harsh treatment. So, we hypothesised that the quantity and/or quality of extracellular vesicles (EVs) in IMF may be reduced. Thus, firstly, we aimed to optimise separation of EVs from IMF and SM and, secondly, we aimed to compare the EV isolates from these two sources. Prior to EV isolation, abundant casein micelles of similar sizes to EVs were removed by treating milk samples with either acetic acid or hydrochloric acid. Samples progressed to differential ultracentrifugation (DUC) or gradient ultracentrifugation (GUC). EV characterisation included BCA, SDS-PAGE, nanoparticle tracking (NTA), electron microscopy (TEM), immunoblotting, and imaging flow cytometry (IFCM). Reduced EV concentrations were found in IMF. SM-derived EVs were intact, while IMF contained disrupted EV-like structures. EV biomarkers were more abundant with isolates from SM, indicating EV proteins in IMF are compromised. Altogether, a suitable method combining acid pre-treatment with GUC for EV separation from milk products was developed. EVs appear to be substantially compromised in IMF compared to SM.

Genomic landscape of geographically structured colour polymorphism in a temperate marine fish

The study of phenotypic variation patterns among populations is fundamental to elucidate the drivers of evolutionary processes. Empirical evidence that supports ongoing genetic divergence associated with phenotypic variation remains very limited for marine species where larval dispersal is a common homogenizing force. We present a genome‐wide analysis of a marine fish, Labrus bergylta, comprising 144 samples distributed from Norway to Spain, a large geographical area that harbours a gradient of phenotypic differentiation. We analysed 39,602 biallelic single nucleotide polymorphisms and found a clear latitudinal gradient of genomic differentiation strongly correlated with the variation in phenotypic morph frequencies observed across the North Atlantic. We also detected a strong association between the latitude and the number of loci that appear to be under divergent selection, which increased with differences in coloration but not with overall genetic differentiation. Our results demonstrate that strong reproductive isolation is occurring between sympatric colour morphs of L. bergylta found at the southern areas and provide important new insights into the genomic changes shaping early stages of differentiation that might precede speciation with gene flow.

Prepontine Shunting for Pseudotumor Cerebri in Previously Failed Shunt Patients: A 5-Year Analysis.

Shunting procedures have a high failure rate when used to treat pseudotumor cerebri (PTC) patients who have failed medical therapy. This failure is believed to be attributable to the collapsibility of the ventricular system when exposed to increased differential pressure gradients in the cerebral spinal fluid compartments caused by ventriculoperitoneal shunts (VPS). To investigate whether prepontine/interpeduncular cistern shunting may be a reasonable alternative to VPS intervention in PTC patients with history of shunt failure. There have been no large series of cisternal-peritoneal shunt (CPS) patients in the PTC population. A retrospective review of 49 patients with placement of CPS for PTC with 2 failed prior shunting procedures was performed. Shunt survivability was based on shunt patency and resolution of ophthalmologic symptoms and cranial nerve deficits. All patients were followed for a minimum of 3 yr with serial ophthalmologic and neurosurgical evaluations. At 3 yr, 44 of the 49 (88.9%) patients had working CPS. Three patients in this group had infections requiring complete shunt removal. Excluding infections, 44 of 46 (95.5%) shunts were functional at 3 yr. There were 3 small, asymptomatic hemorrhages that did not increase patient length of stay, and there were no catastrophic hemorrhages or strokes. There were also no abdominal complications related to shunt placement. CPS is a viable alternative to VPS in PTC patients who have failed traditional shunting methods to give these patients a persistent benefit of a working shunt. The procedure provides this solution with low operative and perioperative morbidity.

Isolation and comparative proteomic analysis of mitochondria from the pulp of ripening citrus fruit

Mitochondria are crucial for the production of primary and secondary metabolites, which largely determine the quality of fruit. However, a method for isolating high-quality mitochondria is currently not available in citrus fruit, preventing high-throughput characterization of mitochondrial functions. Here, based on differential and discontinuous Percoll density gradient centrifugation, we devised a universal protocol for isolating mitochondria from the pulp of four major citrus species, including satsuma mandarin, ponkan mandarin, sweet orange, and pummelo. Western blot analysis and microscopy confirmed the high purity and intactness of the isolated mitochondria. By using this protocol coupled with a label-free proteomic approach, a total of 3353 nonredundant proteins were identified. Comparison of the four mitochondrial proteomes revealed that the proteins commonly detected in all proteomes participate in several typical metabolic pathways (such as tricarboxylic acid cycle, pyruvate metabolism, and oxidative phosphorylation) and pathways closely related to fruit quality (such as γ-aminobutyric acid (GABA) shunt, ascorbate metabolism, and biosynthesis of secondary metabolites). In addition, differentially abundant proteins (DAPs) between different types of species were also identified; these were found to be mainly involved in fatty acid and amino acid metabolism and were further confirmed to be localized to the mitochondria by subcellular localization analysis. In summary, the proposed protocol for the isolation of highly pure mitochondria from different citrus fruits may be used to obtain high-coverage mitochondrial proteomes, which can help to establish the association between mitochondrial metabolism and fruit storability or quality characteristics of different species and lay the foundation for discovering novel functions of mitochondria in plants.

On bending consistency of Timoshenko beam using differential and integral nonlocal strain gradient models

AbstractIn this work, the static bending response of Timoshenko beam under different boundary and loading conditions is analyzed and compared with the application of nonlocal strain gradient models in differential (DNSGM) and integral (INSGM) forms. High‐order and standard boundary conditions are introduced for DNSGM, while the relation between strain and nonlocal stress are expressed as integral equations for INSGM. The differential equations for DNSGM and integro‐differential equations for INSGM are solved directly with the Laplace transformation. The explicit expression for bending deflection and rotation is derived uniquely with eight unknown constants for both DNSGM and INSGM. The results obtained with current models are validated against to the existing results in literature. On the static bending of Timoshenko beam subjected to different boundary and loading conditions, inconsistent responses occurs for DNSGM, while consistent softening and toughening responses can be obtained for INSGM.

Ultrastructural and molecular analysis of the origin and differentiation of cells mediating brittle star skeletal regeneration

BackgroundRegeneration is the ability to re-grow body parts or tissues after trauma, and it is widespread across metazoans. Cells involved in regeneration can arise from a pool of undifferentiated proliferative cells or be recruited from pre-existing differentiated tissues. Both mechanisms have been described in different phyla; however, the cellular and molecular mechanisms employed by different animals to restore lost tissues as well as the source of cells involved in regeneration remain largely unknown. Echinoderms are a clade of deuterostome invertebrates that show striking larval and adult regenerative abilities in all extant classes. Here, we use the brittle star Amphiura filiformis to investigate the origin and differentiation of cells involved in skeletal regeneration using a combination of microscopy techniques and molecular markers.ResultsOur ultrastructural analyses at different regenerative stages identify a population of morphologically undifferentiated cells which appear in close contact with the proliferating epithelium of the regenerating aboral coelomic cavity. These cells express skeletogenic marker genes, such as the transcription factor alx1 and the differentiation genes c-lectin and msp130L, and display a gradient of morphological differentiation from the aboral coelomic cavity towards the epidermis. Cells closer to the epidermis, which are in contact with developing spicules, have the morphology of mature skeletal cells (sclerocytes), and express several skeletogenic transcription factors and differentiation genes. Moreover, as regeneration progresses, sclerocytes show a different combinatorial expression of genes in various skeletal elements.ConclusionsWe hypothesize that sclerocyte precursors originate from the epithelium of the proliferating aboral coelomic cavity. As these cells migrate towards the epidermis, they differentiate and start secreting spicules. Moreover, our study shows that molecular and cellular processes involved in skeletal regeneration resemble those used during skeletal development, hinting at a possible conservation of developmental programmes during adult regeneration. Finally, we highlight that many genes involved in echinoderm skeletogenesis also play a role in vertebrate skeleton formation, suggesting a possible common origin of the deuterostome endoskeleton pathway.

Solution of chemical dynamic optimization systems using novel differential gradient evolution algorithm

Optimization for all disciplines is essential and relevant. Optimization has played a vital role in industrial reactors’ design and operation, separation processes, heat exchangers, and complete plants in Chemical Engineering. In this paper, a novel hybrid meta-heuristic optimization algorithm which is based on Differential Evolution Gradient Evolution and Jumping Technique (+) named Differential Gradient Evolution Plus (DGE+) is presented. The main concept of this hybrid algorithm is to enhance its exploration and exploitation ability. The proposed algorithm hybridizes the above-mentioned algorithms with the help of an improvised dynamic probability distribution, additionally provides a new shake off method to avoid premature convergence towards local minima. The performance of is investigated in thirteen benchmark unconstraint functions, and the results are compared to the other state-of-the-art meta-heuristics. The comparison shows that the proposed algorithm can outperform the other state-of-the-art meta-heuristics in almost all benchmark functions. To evaluate the precision and robustness of the it has also been applied to complex chemical dynamic optimization systems such as optimization of a multimodal continuous stirred tank reactor, Lee-Ramirez bioreactor, Six-plate gas absorption tower, and optimal operation of alkylation unit, the results of comparison revealed that the proposed algorithm can provide very compact, competitive and promising performance overall complex non-linear chemical design problems.

Preferred Configuration and Detection Limits Estimation of Magnetic Gradient Tensor System

The magnetic gradient tensor system (MGTS) based on the fluxgate sensors array replaces partial differentials with the sensors reading difference to approximate the magnetic field gradient, but it introduces structural errors at the mean time. A good structure design with reasonable parameters can reduce structural errors and expand the theoretical detection range of the MGTS. From the analysis of the complete 18-uniaxial MGTS, five simplified structures of the MGTS were summarized, which include the plane cross, equilateral triangle, square, right-angle tetrahedron, and regular tetrahedron. The differential magnetic gradient tensor measurement matrixes of different structures were also provided, where we found the plane-cross structure produces the smallest structural error. Moreover, the theoretical detection limits expression of the MGTS to the magnetic dipole was derived. The detection limit boundary of the MGTS is related to the sensor’s accuracy, the array baseline distance, and the magnetization direction and magnetic moment magnitude of the source. In actual heading-line surveys, the magnetic moments of four typical small magnets were successfully estimated by the magnetic dipole positioning method, and the theoretical detection limits of the built plane-cross MGTS aiming at the four magnets were estimated. The results show that the estimation accuracy of the theoretical detection limits of MGTs is ±0.5 m.

Isolation and Quality Control of Functional Mitochondria.

Even in times, when the study of mitochondria in their natural cellular context is becoming more and more popular, some scientific questions still require the preparation of isolated mitochondria. Numerous protocols are available being adapted for different cell or tissue types allowing isolation of "pure" mitochondria trying to preserve their "structural and functional" integrity. In this chapter, we intend to provide a more general framework introducing differential isopycnic density gradient centrifugation strategy with a special focus sensitizing for the specific challenges coming along with this method and how to obtain "functional," enriched, "intact" mitochondria. Due to the fact that in any study dealing with these organelles standardized processing is mandatory, here we describe a strategy addressing quality control of prepared intact mitochondria. The quality control should be an integrated part of all isolation processes. The underlying protocol should be seen as starting point and has to be carefully adjusted to cover different sample types used for the diverse research questions.

Do echolocating toothed whales direct their acoustic gaze on- or off-target in a static detection task?

Echolocating mammals produce directional sound beams with high source levels to improve echo-to-noise ratios and reduce clutter. Recent studies have suggested that the differential spectral gradients of such narrow beams are exploited to facilitate target localization by pointing the beam slightly off targets to maximize the precision of angular position estimates [maximizing bearing Fisher information (FI)]. Here, we test the hypothesis that echolocating toothed whales focus their acoustic gaze askew during target detection to maximize spectral cues by investigating the acoustic gaze direction of two trained delphinids (Tursiops truncatus and Pseudorca crassidens) echolocating to detect an aluminum cylinder behind a hydrophone array in a go/no-go paradigm. The animals rarely placed their beam axis directly on the target, nor within the narrow range around the off-axis angle that maximizes FI. However, the target was, for each trial, ensonified within the swath of the half-power beam width, and hence we conclude that the animals solved the detection task using a strategy that seeks to render high echo-to-noise ratios rather than maximizing bearing FI. We posit that biosonar beam adjustment and acoustic gaze strategies are likely task-dependent and that maximizing bearing FI by pointing off-axis does not improve target detection performance.

Preparation of "Functional" Mitochondria: A Challenging Business.

As the powerhouse of the cell, mitochondria, plays a crucial role in many aspects of life, whereby mitochondrial dysfunctions are associated with pathogenesis of many diseases, like neurodegenerative diseases, obesity, cancer, and metabolic as well as cardiovascular disorders. Mitochondria analysis frequently starts with isolation and enrichment procedures, which have become increasingly important in biomedical research. Unfortunately, isolation procedures can easily cause changes in the structural integrity of mitochondria during in vitro handling having impact on their function. This carries the risk that conclusions about isolated mitochondria may be drawn on the basis of experimental artifacts. Here we critically review a commonly used isolation procedure for mitochondria utilizing differential (gradient) centrifugation and depict major challenges to achieve "functional" mitochondria as basis for comprehensive physiological studies.

Peripheral blood and tissue assessment highlights differential tumor-circulatory gradients of IL2 and MIF with prognostic significance in resectable pancreatic ductal adenocarcinoma

ABSTRACT Various reports have pointed out the potential of cytokines as diagnostic and prognostic biomarkers for pancreatic ductal adenocarcinoma (PDA). Nonetheless, the evidence is contradictory and the role of chronic inflammation and relationship between circulatory and corresponding tumoral cytokine levels remain elusive. Utilizing a broad array of cytokines, we identified two opposing parameters: serum levels of interleukin 2 (IL2) and macrophage migration inhibitory factor (MIF) are diagnostic and prognostic factors. While low IL2 levels are associated with PDA, they also relate to a favorable prognosis of patients. In contrast, high MIF levels are associated with PDA and simultaneously related to an unfavorable outcome. MIF levels are associated with the intratumoral density of M2 macrophages (CD163+). Focusing on the tumor-to-serum gradient, we unveiled a different pattern of compartmental cytokine expression between IL2 and MIF. Our findings indicate that an extra-tumoral source of IL2 exists in PDA patients leading to increased detectability in the circulatory system. In case of MIF, the tumor microenvironment is presumably the main site of production and thereby reflected by serum measurements. Taken together, our study describes IL2 and MIF levels as biomarker candidates for diagnosis and prognosis of PDA, highlighting the need for compartmental cytokine analyses. From the perspective of tumor immunobiology, we identify multiple inflammatory states (proposed as types I–III) and see that systemic chronic dysregulation, independent of tumor microenvironment, can be measured and is a possible tool for stratification. Thus, direct correlation of local cytokine levels to peripheral blood levels needs to be regarded with caution.

Privacy-Preserving Mechanism in Smart Home Using Blockchain

The IoT, or Internet of Things has been a major talking point amongst technology enthusiasts in recent years. The internet of thing (IoT) has been emerged and evolved rapidly, making the world's fabric around us smarter and more responsive. The smart home uses one such transformation of IoT, which seems to be the wave of the future. However, with the increasing wide adoption of IoT, data security, and privacy concerns about how our data is collected and shared with others, has also risen. To solve these challenges, an approach to data privacy and security in a smart home using blockchain technology is proposed in this paper. We propose authentication scheme that combines attribute-based access control with smart contracts and edge computing to create a secure framework for IoT devices in smart home systems. The edge server adds scalability to the system by offloading heavy processing activities and using a differential privacy method to aggregate data to the cloud securely and privately. We present several aspects of testing and implementing smart contracts, the differential private stochastic gradient descent algorithm, and system architecture and design. We demonstrate the efficacy of our proposed system by fully examining its security and privacy goals in terms of confidentiality, integrity, and availability. Our framework achieves desired security and privacy goals and is resilient against modification, DoS attacks, data mining and linkage attacks. Finally, we undertake a performance evaluation to demonstrate the proposed scheme's feasibility and efficiency.

Barodontalgia among Aircrew of Bangladesh Air Force

subjected to atmospheric pressure changes and have an influence on flights. Barodontalgia is caused whenever the pulp is exposed to differential pressure gradient.
 Objective: To see the barodontalgia among aircrew of Bangladesh Air Force.
 Methodology: A cross-sectional study was carried out in Dental wing medical squadron BAF base Basher Dhaka. The study participants were recruited during one year among all the pilots and crewmembers attending departments specializing in medical follow-up at the study period from the Bangladesh Air Force.
 Results: Among the 50 barodontalgia group, most 39(78%) of the respondents were found technical and military flying whereas 50 without barodontalgia group 38(76%) specifically in military flying. In barodontalgia, 62% respondents were found in moderate pain (4-6), 26% in mild pain (1-3) and 32% in severe pain (7-10). In barodontalgia, 50% respondents were descent of barodontalgia, 52% were altitude where barodontalgia was reported to appear during the flight was <4000 meters and 70% were flight speed was 500-1000 km/h. Most of the respondents were found specifically in commercial flights in patients with barodontalgia. Majority pain intensity was found moderately in barodontalgia
 JAFMC Bangladesh. Vol 15, No 2 (December) 2019: 186-188

Variable Deformability of Irreversibly Sickled Erythrocytes

The relationship of altered deformability of irreversibly sickled cells (ISC) to their morphological and physiologic characteristics was evaluated in this study. ISC obtained by differential centrifugation and density gradient sedimentation were separated and enriched into hard and soft populations on the basis of their ability to pass through Nuclepore filters with an average pore size of 3.0 mu. Measurement of deformability by micropipette and Nuclepore elastimetry documented marked differences of erythrocyte rigidity in the two populations. Yet ISC morphology, intracellular viscosity determinants (mean cell hemoglobin concentration, density profile gradient, hemoglobin composition), and surface area geometry (mean cell volume, osmotic fragility) were similar in populations of hard and soft ISC. The similarity in intracellular viscosity and surface area geometry suggests that an intrinsic membrane alteration is responsible for the difference in deformability of filtration separated populations of ISC. Hard ISC may be more important to the pathophysiology of sickle cell disease than soft ISC, though ISC counts on peripheral blood smears would not be of help in distinguishing the two populations.

Quantitative Analysis of the Measurable Areas of Differential Magnetic Gradient Tensor Systems for Unexploded Ordnance Detection

Achieving effective detection of unexploded ordnance (UXO) is of great significance for ensuring the safety of human lives and regional economic development. Differential magnetic tensor gradient systems have strong application prospects for UXO detection because of their low orientation requirements and exceptional sensitivity to weak magnetic fields. These systems usually have a hollow ring-shaped measurable range, referred to as the “measurable area”. With the rapid advancement of the tensor measurement system, it is necessary to further analyse the measurable area performance. In this paper, a simulation method based on a target magnetic dipole revolving around such a measurement system is designed for evaluating the measurable area. An improved Frobenius norm is adopted to compare the measured tensor data, and the centre distance is used instead of the baseline distance to better describe the scale of the measurement system. The measurable areas of planar cross-shaped, square, and triangular structures are studied, as well as the corresponding influencing factors. Finally, the quantitative relationships between the measurable area performance of the three structures and the magnetic dipole moment direction, the sensor accuracy, and the centre distance of the measurement system are obtained.

On the vibration of nanobeams with consistent two-phase nonlocal strain gradient theory: exact solution and integral nonlocal finite-element model

Recently, it has been proved that the common nonlocal strain gradient theory has inconsistence behaviors. The order of the differential nonlocal strain gradient governing equations is less than the number of all mandatory boundary conditions, and therefore, there is no solution for these differential equations. Given these, for the first time, transverse vibrations of nanobeams are analyzed within the framework of the two-phase local/nonlocal strain gradient (LNSG) theory, and to this aim, the exact solution as well as finite-element model are presented. To achieve the exact solution, the governing differential equations of LNSG nanobeams are derived by transformation of the basic integral form of the LNSG to its equal differential form. Furthermore, on the basis of the integral LNSG, a shear-locking-free finite-element (FE) model of the LNSG Timoshenko beams is constructed by introducing a new efficient higher order beam element with simple shape functions which can consider the influence of strains gradient as well as maintain the shear-locking-free property. Agreement between the exact results obtained from the differential LNSG and those of the FE model, integral LNSG, reveals that the LNSG is consistent and can be utilized instead of the common nonlocal strain gradient elasticity theory.

Cortical gradients of functional connectivity are robust to state-dependent changes following sleep deprivation

Sleep deprivation leads to significant impairments in cognitive performance and changes to the interactions between large scale cortical networks, yet the hierarchical organization of cortical activity across states is still being explored. We used functional magnetic resonance imaging to assess activations and connectivity during cognitive tasks in 20 healthy young adults, during three states: (i) following a normal night of sleep, (ii) following 24hr of total sleep deprivation, and (iii) after a morning recovery nap. Situating cortical activity during cognitive tasks along hierarchical organizing gradients based upon similarity of functional connectivity patterns, we found that regional variations in task-activations were captured by an axis differentiating areas involved in executive control from default mode regions and paralimbic cortex. After global signal regression, the range of functional differentiation along this axis at baseline was significantly related to decline in working memory performance (2-back task) following sleep deprivation, as well as the extent of recovery in performance following a nap. The relative positions of cortical regions within gradients did not significantly change across states, except for a lesser differentiation of the visual system and increased coupling of the posterior cingulate cortex with executive control areas after sleep deprivation. This was despite a widespread increase in the magnitude of functional connectivity across the cortex following sleep deprivation. Cortical gradients of functional differentiation thus appear relatively insensitive to state-dependent changes following sleep deprivation and recovery, suggesting that there are no large-scale changes in cortical functional organization across vigilance states. Certain features of particular gradient axes may be informative for the extent of decline in performance on more complex tasks following sleep deprivation, and could be beneficial over traditional voxel- or parcel-based approaches in identifying realtionships between state-dependent brain activity and behavior.