Mechanical Disturbance Research Articles

Relative importance of region, seasonality and weed management practice effects on the functional structure of weed communities in French vineyards

Winegrowers have diversified their weed management practices over the last two decades changing the structure and the composition of weed communities. Complementary to taxonomic studies, trait-based approaches are promising ways for a better understanding of weed community responses to environmental and agronomic filters. In the present study, the impacts of climate, soil characteristics, seasons and weed management practices (chemical weeding, tillage and mowing) were assessed on weed communities from 46 plots in three French wine-growing regions (Champagne, Languedoc and Rhône valley). These agro-environmental gradients structuring weed communities according to their combinations of traits were highlighted using multivariate analysis (RLQ). The impacts of these filters on Community Weighted Means (CWM) and Community Weighted Variance (CWV) of weed communities were analysed using mixed and null modelling. Our results showed that spatio-temporal and weed management practice variables explained from 13% to 48% of the total variance of CWM (specific leaf area, maximum height, seed mass, flowering onset and duration and lateral spread). Region, seasonality and management practices explained 53%, 28% and 19% of CWM marginal variance, respectively. Weed management impacted CWM and CWV through two main gradients: (i) a soil disturbance gradient with high mechanical disturbance of soil in tilled plots and low mechanical disturbance in chemically weeded plots and (ii) a vegetation cover gradient with high vegetation abundance in mowed plots compared to barer soils in tilled and chemically weeded plots. In Languedoc, chemical weeding filtered weed communities with ruderal strategy trait values (low seed mass, small-stature) while mowed communities were more competitive (higher seed mass, higher stature and lower SLA). In Languedoc and Champagne, tillage favoured communities with high seed mass that increases the viability of buried seeds and high lateral spread values associated to the ability to resprout after tillage. This study demonstrated that trait-based approaches can be successfully applied to perennial cropping systems such as vineyards, in order to understand community assembly to better guide weed management practices.

Intelligent testing prototype for monitoring thermal variables in a thermal chamber according to optimize an ultrasonic washing machine

The following article shows the mathematical analysis, simulations, design and experimental tests of an intelligent prototype for monitoring the physical variables: temperature, which is measured and recorded from inside a system. It contains a platform in a movement more than 3 degrees of freedom (DOF) that is coupled to 4 springs that allow the mechanical movement of the platform that supports the monitoring system. The recording system has the ability to be inside the thermal system (not outside the data monitoring, which is the usual way) for monitoring the thermal variables regardless of mechanical disturbances of movement that generally physical-chemical processes require it. The complexity of the case is that the monitoring hardware must be inserted into a closed system at the controlled range of work from 25 to 70 degrees Celsius and the composition of 3 DOF adapts the recording system to achieve a robust control for a washing machine that uses ultrasound. Since connection and wiring problems disturb the transfer of information, if the monitoring system is outside the thermal system. For this reason, this designed system has the robustness of hardware to isolate the heat that is produced in the thermal camera with respect to the interior of the recorder. Also the appropriate isolation for the hardware that contains the monitoring system is thermally analyzed, which implies that outside the system the process can be from 25 to 70 degrees Celsius and inside the prototype, where the logger circuitry is located, it is around 25 degrees Celsius. However, the analysis of correct filtering and self-control of the system is also necessary during the processing of the information of registered thermal variables, since a large part of the disturbances for data collection is given by the mechanical movement of two degrees of freedom of the thermal system [1], [2]. Finally, it is suggested for a future improvement of this article, the replacement of traditional (electromechanical) sensors by sensors based on nanostructures, because a large part of solutions and strategies for filtering and control through software can be optimized with robust and fast-response sensors. Moreover, this new sensor can avoid mechanical and electromagnetic disturbances.

Secure SDM–OFDM signal transmission based on memristive neural network

This paper proposes a physical layer security strategy of space division multiplex orthogonal frequency division multiplexing system based on memristive neural network (MNN). Among them, the two-level chaotic control, the application of the memristive chaotic model with conditional symmetry and the encryption of the MNN are all proposed for the first time in the access network. The memristive chaotic model with conditional symmetry generates 8 multiple masking factors and achieves high-security encryption. In the encryption process, the key space is selected by Logistic mapping, and the MNN encryption mechanism disturbances and compresses bits. The proposed encryption strategy has been proved on the experimental platform. The generated OFDM signals are modulated, which transmit data rate of 124.4 Gb/s over the 2 km multi-core fiber (MCF). Bit error rate (BER) and different anti-interference are analyzed in experiments. The key space of this proposed scheme is 2×10399, which is large enough number to effectively resist any brute force or illegal optical network units (ONUs) intrusion in passive optical network (PON). The results show that the proposed SDM–OFDM​ scheme has high sensitivity and security. This scheme has very reliable safety performance and benefit improvement, and is very promising in the future SDM–OFDM system.

Highly Birefringent Anti‐Resonant Hollow‐Core Fiber with a Bi‐Thickness Fourfold Semi‐Tube Structure

AbstractThe optical performance characteristics of anti‐resonant hollow‐core fibers (known as AR‐HCFs or ARFs) are improving rapidly, but the polarization maintaining issue with these fibers remains unresolved. Although a regular nonbirefringent ARF can maintain high polarization purity under static conditions, it cannot resist mechanical disturbances. In this work, by designing a bi‐thickness semi‐tube ARF structure with fourfold rotational symmetry, the first ARF with a level of birefringence close to 10−4is fabricated. The proposed ARF features a combination of phase birefringence of 9.1 × 10−5, a minimum loss of 185 dB km−1, a bandwidth of 133 nm, and single‐mode operation. Furthermore, the ARF shows high resistance to fiber bending and wide‐range temperature variations, thus confirming that this carefully designed ARF can serve as a practical workhorse in polarization‐related optical fiber applications.

CORRELATION BETWEEN FOCAL CHOROIDAL EXCAVATION AND UNDERLYING RETINOCHOROIDAL DISEASE: A Pathological Hypothesis From Clinical Observation.

To evaluate focal choroidal excavation (FCE) in eyes with various diseases using multimodal imaging modalities and to investigate the correlation of FCE and underlying chorioretinal diseases. This retrospective observational study included 62 eyes from 56 patients who were identified by optical coherence tomography as having FCE. All included patients underwent comprehensive clinical examinations and multimodal imaging to identify and detect the characteristics of FCE and its correlation with underlying chorioretinal diseases. All included patients were of Chinese descent, and the median age at diagnosis was 43 years (range: 15-66). Seventy-three FCEs appeared in these included eyes. Most FCEs were formed at sites with anatomical changes caused by various chorioretinal diseases. Choroidal osteoma, punctate inner choroidopathy, and central serous chorioretinopathy were the most common etiologies of FCE. During follow-up, 14 eyes (22.58%) exhibited a pattern change and three eyes (4.84%) developed new-onset choroid neovascularization. Focal choroidal excavation is a common sign found in a variety of chorioretinal diseases. Processes that involve impairment or tissue loss of the outer retina and inner choroid and disrupt the balance of intraocular pressure and choroidal pressure because of mechanical disturbance may play a role in FCE formation.

No recovery of a large-scale anthropogenic sediment disturbance on the Pacific seafloor after 77 years at 6460 m depth

Habitat restoration and recolonisation of benthic communities after physical perturbation in the deep sea has long been thought to be extremely slow. This study reports on a serendipitous opportunity to survey the current state of a large mechanical disturbance of sediments at 6460 m in the Pacific Ocean. The impact was caused 77 years ago by the sinking of the USS Johnston. The surrounding debris field had little impact on the sedimentary habitat, other than in the provision of artificial hard substrates, while the troughs that formed as the ship impacted the seafloor and slid down the slope of the Philippine Trench were still completely void of animal tracks and burrows, or any observable epifauna, and in some areas subsurface stratification was still exposed at the surface. This suggests that mechanical perturbations of sediments in the deep Pacific may remain ecologically significant for, at the very least, 100 years.

Inhibition of \u03b2-catenin signaling attenuates arteriovenous fistula thickening in mice by suppressing myofibroblasts

BackgroundArteriovenous fistula (AVF) is the most important vascular access for hemodialysis; however, preventive treatment to maintain the patency of AVFs has not been developed. In endothelium, β-catenin functions in both the intercellular adherens complex and signaling pathways that induce the transition of endothelial cells to myofibroblasts in response to mechanical stimuli. We hypothesize that mechanical disturbances in the AVF activate β-catenin signaling leading to the transition of endothelial cells to myofibroblasts, which cause AVF thickening. The present study aimed to test this hypothesis.MethodsChronic kidney disease in mice was induced by a 0.2% adenine diet. AVFs were created by aortocaval puncture. Human umbilical vein endothelial cells (HUVECs) were used in the cell experiments. A pressure-culture system was used to simulate mechanical disturbances of the AVF.ResultsCo-expression of CD31 and smooth muscle alpha-actin (αSMA), loss of cell–cell adhesions, and the expression of the myofibroblast marker, integrin subunit β6 (ITGB6), indicated transition to myofibroblasts in mouse AVF. Nuclear translocation of β-catenin, decreased axin2, and increased c-myc expression were also observed in the AVF, indicating activated β-catenin signaling. To confirm that β-catenin signaling contributes to AVF lesions, β-catenin signaling was inhibited with pyrvinium pamoate; β-catenin inhibition significantly attenuated AVF thickening and decreased myofibroblasts. In HUVECs, barometric pressure-induced nuclear localization of β-catenin and increased expression of the myofibroblast markers, αSMA and ITGB6. These changes were attenuated via pretreatment with β-catenin inhibition.ConclusionsThe results of this study indicate that mechanical disturbance in AVF activates β-catenin signaling to induce the transition of endothelial cells to myofibroblasts. This signaling cascade can be targeted to maintain AVF patency.

Experimental study on vibration-induced clamping force reduction in fuel cell structures

When applied to transportation systems, fuel cell structures are exposed to external mechanical disturbance including shocks and harmonic excitations from operating components. To minimize performance degradation from machine operations, the fuel cell structure needs to be examined via vibration reliability tests. In this study, the reduction in the clamping force of the stack by random vibrations was investigated by experiments. The stack mass and gasket were clamped with bolts for vibration tests. The vibration induced shear movements between clamped stacks. To estimate the vibration input magnitudes, the Dirlik method was used. The reduction in the stack clamping force was estimated using the Basquin's power law. The clamping force decreased by the shear vibration input to the stack structure. The degree of clamping force reduction was larger for the heavier stack. When the stacks were separated by the gasket the reduction became smaller. Through the Dirlik method, the vibration reliability of the stack was evaluated. This information provides severity of the external vibration on the stack functionality.

Metodické aspekty v procese edukácie reštaurátora na príklade sôch spojených s architektúrou

Stone plastic elements and sculptures are a frequent part of historic facades. The degree of their mechanical disturbance is often significant, the original forms and details are destroyed. In the process of their restoration are consolidation and conservation a first step. However, the main issues are related to the reconstruction of their original expression. In this context, basic methodological issues need to be addressed, which are an important part of the restorer's education. The article deals with three examples of sculptures connected with architecture, that were restored in the Academy of fine arts and design in Bratislava. Each of them represented a different degree of use of reconstruction methods.

Соотношения взаимности для открытых нелинейных систем в переменных полях

А proof of reciprocity relations for nonlinear systems in inhomogeneous variable electric and magnetic fields in the presence of unsteady spin currents, thermodynamic flows and mechanical disturbances is obtained by the Kubo method in the approximation of Markov relaxation and locally quasi-equilibrium distribution.

Нарушения эпигенетической регуляции экспрессии генов при болезнях импринтинга

Epigenetic regulation is hereditary and non-hereditary changes in the expression of a particular gene without any corresponding structural changes in its nucleotide sequence. Genomic imprinting is an epigenetic mechanism for regulating the expression of homologous genes depending on parental origin, i.e., they are expressed monoallelically in the mammalian diploid cell. Being genetically imprinted, only the maternal or only the paternal genome is unable to ensure normal embryonic development. The most studied epigenetic modification, which plays one of the main roles in the maintenance of imprinting processes, is the specific methylation of cytosine in CpG-dinucleotides. All known imprinted genes contain differential DNA methylation regions on homologous parent chromosomes, which are necessary for their monoallelic expression. However, it is now known that not only DNA methylation, but chromatin remodeling, histone modifications, and non-coding RNAs also ensure the proper functioning of imprinted genes in the human body. Structural and functional disturbances of epigenetic mechanisms lead to imprinting diseases.

Review: Bioavailability and Activity Prediction of Bioactive Compounds of Red Fruit (Pandanus conoideus Lam.) and Pandan Grape (Sararanga sinousa Hemsley) by in silico Method

Red Fruit (RF) and Pandan grape (PG) contained bioactive compounds that good for health. The structure influenced the availability and activity, including the interaction with another in the body. It needs time and financial consumption, whereas bioinformation technology offers the solution. The research aims to predict the availability and activity of RF and PG compounds by in silico method based on the SAR. Fourteen RF and PF phenolics were evaluated for availability, antioxidant, and antiglycation activity during binding to HSA. The flavonoids showed Pa>0,7 for antioxidant in general, free radical scavenging, and lipid peroxidase inhibitor activity. The availability was shown by the ligand’s capability to bind to HSA. The order of affinity energy from the largest to the smallest was RF flavonoid > PG anthocyanin > GP phenolic acids. Taxifolin and Quercetin still had antioxidant activity during binding because there are free hydroxyl groups. PG chlorogenic acid and RF flavonoids play as an anti-diabetic through antioxidant mechanism and HSA glycation disturbance. Based on this review, in silico method is effective as an analysis tool for the activity and mechanism prediction of food bioactive compounds.

Nonlinear Controller for the Laser Fiber Using PID Controller

We show that a software architecture based on machine learning and adaptive control advances makes self-tuning optics possible. Commercially available optical telecom components may be combined with servo controllers to develop a training and execution software module that can self-tune the laser cavity even when it is switched off. Mechanical and/or environmental disturbances may aid in frequency comb stabilization. An exhaustive search of state space is used in the algorithm training stage to find the optimum performance areas for one or more objectively interesting functions. The technique of implementation stage starts by identifying the variable space using a sparse sensing approach, then settles on a near-optimal solution and maintains it using the extremum seeking control protocol.

ODE System Identification of a Dynamic Weight Acquisition Process Using Feedforward Neural Networks

For detailed modelling of the dynamic weight acquisition process for combination scales, very high effort is required to obtain white box models, since the mechatronic system is highly dependent on fluctuating properties. They are related to the products to be weighed such as piece weight, target weight, the type of impact to the weighing bucket, to the load cell, and superimposed external mechanical and electric disturbances. Therefore this work develops a black box approach to model these measurement systems. The black box model consists of a system of ordinary differential equations which are described as feedforward neural network. The network is trained by 5,897 load cell signal measurements of the impact pulse of plastic anchors with different target weights. The ODE system of the weight acquisition is described by a black box model with a mean error of the static weight value of 0.28 % and a standard deviation of the error of the static weight value of 0.93%. Analyses show that the loss is more scattered for heavier target weight than for lighter target weight. External disturbances could not be generated in the test due to the missing input signal.

The theoretical modeling of the dynamic compaction process of forest soil.

Due to the growing demand for timber, forest soils are increasingly exposed to mechanical disturbances, caused by forestry equipment. Even though using skidding machines to transport wood is detrimental to the physical state of the soil, this method remains the most common. Hence, there is a need to model the impact of skidding systems on the upper (fertile) layer of the soil. This study aims to develop such a model using the D'Alembert principle, the method of Laplace transforms, and a modified Kelvin-Voigt model. The work shows that subdividing the tractor-bundle-soil system makes it possible to consider the dynamic effect of the vibrating tractor on the soil and soil's ability to undergo deformation separately. In addition, the study developed individual models for the first subsystem that determine vibration effects on soil caused by an unloaded tractor and two loaded skidding systems using different methods of semi-suspended skidding. The present findings can be used to predict the degree of dynamic soil compaction without conducting direct on-site experiments and thus minimize the negative impact of forestry operations on the local ecosystem. The current data also allow simplifying design models for complex forwarders.

Evaluation of Changes in Serum Insulin like Growth Factor-1 Levels with Growth Modulation via Twin Block TherapyA Prospective Clinical Study

Introduction: Serum insulin like growth factor is a pertinent growth regulator in bone and cartilage, therefore assessment of changes in serum Insulin like Growth Factor (IGF) levels in patients undergoing functional appliance therapy can act as valuable tool to understand the mode of action of functional appliances. Aim: To evaluate the changes in serum Insulin like Growth Factor-1 (IGF-1) levels in the patients undergoing twin block therapy and to establish IGF-1 as a biochemical marker produced in response to mechanical disturbance in the condylar region by twin block appliance. Materials and Methods: This prospective clinical trial was conducted in the Department of Orthodontics and Dentofacial Orthopedics, Postgraduate Institute of Dental Sciences, Rohtak, Haryana, India from May 2014 to November 2015. Total 27 patients included in study, divided into two groups, the test group which comprised of 15 patients treated with standard twin block appliance therapy and the control group which comprised of 12 patients not treated with the same. Serum samples were collected from test group and control group patients at four time intervals (pretreatment (T0), 1 month (T1), 3 months (T3) and 6 months (T6)) and subjected to EnzymeLinked Immunosorbent Assay (ELISA) to measure IGF-1 levels. The data thus obtained was subjected to statistical analysis using Statistical Package for the Social Sciences (SPSS) for windows 20.0. Intragroup differences were evaluated using paired t-test, while intergroup differences were evaluated using independent sample t-test. The p-value<0.05 was considered as statistically significant. Results: The data was obtained from 11 patients (6 males and 5 females) in the test group and 10 patients (6 males and 4 females) in the control group after elimination of dropouts. Mean age of the test group subjects was 12.8±0.9 years and that of control group subjects was 13.1±0.9 years. The mean IGF-1 levels in the test group were 124.5 ng/mL (T0), 126.27 ng/mL (T1), 130.90 ng/mL (T3) and 135.54 ng/mL (T6). In the control group, 151.5 ng/mL (T0), 140.8 ng/mL (T1), 157.8 ng/mL (T3) and 120.2 ng/ mL (T6). In the test group, mean levels of serum IGF-1 did not change significantly when baseline levels were compared with the serum IGF-1 levels at T1 (0.467), T3 (0.729) and T6 (0.62) of functional appliance therapy, although an increase in IGF-1 levels was noted at each interval. Comparison of serum IGF-1 levels of test and control group showed no statistically significant difference between the groups at T0, T1, T3 and T6. Conclusion: Functional appliance therapy was not found to be associated with concomitant increase in serum IGF-1 levels.

Reciprocity relations for open nonlinear systems in variable fields

A proof of reciprocity relations for nonlinear systems ininhomogeneous variable electric and magnetic fields in the presence ofunsteady spin currents, thermodynamic flows and mechanical disturbances isobtained by the Kubo method in the approximation of Markov relaxation andlocally quasi-equilibrium distribution. Keywords: Nonlinear distributed systems, locally quasi-equilibrium distribution, Markov relaxation, spin current, reciprocity\

Increasing misalignment of spatial resolution between investigative and disturbance scales alters observed responses of an infaunal community to varying disturbance severities

On the northern coast of British Columbia, Canada, we used the infaunal invertebrate community (meiofauna) of the Cassiar Cannery mudflat to assess responses to different severities of a mechanical disturbance. Overall, the infaunal community was effective in identifying if a disturbance had occurred, regardless of disturbance severity. However, considerable overlap was observed between infaunal communities in disturbed and reference habitat. Variation between disturbed and reference habitats was primarily the result of differences in the relative abundances of five taxa (Oligochaeta, Nematoda, Nippoleucon hinumensis, Capitella species complex, and Macoma balthica). Conversely, the infaunal community was not an effective tool in differentiating between disturbance severities, likely because of the subtle differences observed between infaunal successional stages. We also assessed how increasing misalignment of spatial resolution between sampling and disturbance scales influenced analytical findings. As misalignment between the scale of disturbance and investigation increased, Type I and Type II errors became more common in our analyses. Our findings indicate that intertidal infaunal communities can be effectively used to study the influence of disturbances upon an ecological system. However, care must be taken to ensure the proper sampling scheme is used, one that overlaps with the scale of disturbance. These findings expand our understanding of how communities respond to disturbance and will be of interest to anyone attempting to study, detect, or mediate anthropogenic and natural disturbances.

Root Growth Was Enhanced in China Fir (Cunninghamia lanceolata) after Mechanical Disturbance by Ice Storm

Accurate estimation of forest biomass and its growth potential could be important in assessing the mitigation potential of forest for climate change. However, severe mechanical disturbance such as stem breakage imposed significant changes to tree individuals in biomass structure, which could bring new inaccuracy to biomass estimation. In order to investigate the influence of severe mechanical disturbance on tree biomass accumulation and to construct accurate models for biomass and carbon storage estimation, this paper analyzed the relationship between tree size and biomass for China fir (Cunninghamia lanceolata (Lamb.) Hook) which suffered stem breakage from, and survived, an ice storm. The performance of independent variables diameter (D) and height (H) of China fir, were also compared in biomass estimation. The results showed that D as an independent variable was adequate in biomass estimation for China fir, and tree height was not necessary in this case. Root growth was faster in China fir which had suffered breakage in the main stem by the ice storm, than China fir which were undamaged for at least 7 years after the mechanical disturbance, which, in addition to biomass loss in stem, caused changes in the allocation pattern of the damaged trees. This suggests biomass models constructed before severe mechanical disturbance would be less suitable in application for a subsequent period, and accurate estimations of biomass and forest carbon storage would take more effort.

The value of erythropoietin in the pathogenesis of anemia of chronic diseases in the rheumatic patients

The features of erythropoietin secretion in patients with a rheumatic pathology and anemia of the chronic diseases in comparison with patients having iron deficiency anemia, as well as the relationship between erythropoietin, hepcidin, proinflammatory, and antiinflammatory cytokines, have been investigated. 126 patients suffering from the rheumatic pathology were examined, including 34 men aged 3655 years and 92 women aged 3860 years. At the same time, 104 (82.5%) patients suffered from anemia, 22 (17.5%) patients did not have it. Patients suffering from anemia, depending on the leading pathogenetic factor, were divided into three groups such as: the 1st group patients suffering from anemia of chronic diseases; 2nd grouppatients suffering from a combination of anemia of chronic diseases and iron deficiency anemia; 3rd grouppatients suffering from iron deficiency anemia. In patients suffering from anemia of chronic diseases, the maximum concentration of interleukin-6, hepcidin, and the minimum concentration of erythropoietin were detected in comparison with the patients suffering from iron deficiency anemia and patients suffering from anemia of chronic diseases, and iron deficiency anemia (p 0.05). The maximum concentration of the erythropoietin has been established in patients suffering from iron deficiency anemia. About the concentrations of interleukin-10 and interleukin-1, tumor necrosis factor-, interferon-, no differences were found in the study groups. A direct correlation was found between the erythropoietin and erythrocytes (r = 0.57), hemoglobin (r = 0.41), hepcidin (r = 0.65). There was a strong negative correlation between the erythropoietin and interleukin-6 (r = 0.75), and a weak relationship with interferon gamma, tumor necrosis factor alpha, interleukin-10, and interleukin-1 (r 0.3). Thus, for patients with a rheumatic profile, a specific molecular profile should be identified, leading to the development of anemia of the chronic diseases, which consists in increased concentrations of hepcidin and interleukin-6 in combination with the insufficient secretion of erythropoietin. The found changes fit into the structure of the previously proposed working version of the classification of anemia of chronic diseases (with a predominant iron deficiency, with disturbances in the regulatory mechanisms of the erythropoiesis, with an insufficient production of erythropoietin). Isolation of the leading factor in the development of anemia of chronic diseases in the future will allow for a more optimal approach to its correction, including with the targeted therapy drugs.