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The stimulating effect of ytterbium nitrate on seed germination, photosynthesis, and accumulation of carbohydrates in the roots of the krim-saghuz dandelion (Taraxacum hybernum) was demonstrated. Differences between lanthanum and ytterbium in their effect on the efficiency of PS II (Y(II)). At a concentration of 100 μmol, lanthanum reduced Y(II) due to an increase in the contribution of the quantum yield of controlled dissipation of a part of the energy (Y(NPQ)), and ytterbium reduced it due to the contribution of irreversible dissipation of energy (Y(NO)). When the concentration of lanthanides was reduced by ten times, the stimulating effect of Y(II) was observed only for ytterbium. In field experiments, plants treated with 10 μmol ytterbium nitrate solution had a 31% higher rate of photosynthesis, which probably influenced the accumulation of rubber and carbohydrates in dandelion roots, which was 13 and 26% higher, respectively, than the untreated plants. [ABSTRACT FROM AUTHOR]

Copyright of Zeitschrift für Aussen- und Sicherheitspolitik is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Zeitschrift für Aussen- und Sicherheitspolitik is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The equipment and observational technique used to obtain dynamic spectra of the solar radio radiation at the KRIM station (Crimean Astrophysical Observatory) that is a part of the e-CAL-LISTO worldwide network are described. The parameters of an antenna fabricated in the Radioastronomy Laboratory of the Crimean Astrophysical Observatory and a method for excluding the instrumental distortions that was developed at the KRIM station are outlined. [ABSTRACT FROM AUTHOR]

Nickel coatings are electrodeposited onto Al0.95Mg0.05 substrates and heat treated to improve the mechanical properties of aluminum alloys. Al0.95Mg0.05 samples were electroplated for varying durations in a stirred nickel-plating Watts bath. The coating adhesion and surface mechanical properties were then improved by heat treatment at 450, 500, and 550 °C with annealing times ranging from 1 to 40 h depending on the diffusion temperature. Microstructural studies using optical microscopy, scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy, and x-ray diffraction reveal that heat treatment results in varying amounts of Al3Ni2 and Al3Ni intermetallic phases. Berkovich microindentation was used to determine sample hardness, and wear tests were performed with a ball-plane tribometer with alternating translation motion. The results show that as-treated substrates have a higher hardness than the original Al0.95Mg0.05 substrates due to the various (Al, Ni) intermetallic growths. The time of Ni deposition in the bath and the temperature/time of annealing influence the intermetallic type, thickness, and crystallinity. In addition, wear behavior demonstrates that unreacted Ni on the top surface is harmful and causes the running-in stage and that after several runs, the coefficient of friction of the as-prepared samples stabilizes between 0.3 and 0.36. [ABSTRACT FROM AUTHOR]

Background: Ideally, suspected airway compression in symptomatic children with lymphobronchial tuberculosis (TB) would be diagnosed using modern computed tomography (CT) assisted by coronal minimum intensity projection (MinIP) reconstructions. However, in TB-endemic regions with limited resources, practitioners rely on conventional radiography for diagnosing TB and its complications. Furthermore, airway compression detected on conventional radiographs would upgrade a patient into the severe category according to the new World Health Organization guidelines, precluding the patient from shorter treatment protocols. The accuracy of conventional radiographs in the context of detecting airway compression in children with TB has not been specifically evaluated against an imaging gold standard. Objective: We aimed to compare frontal chest radiographs against thick-slab angled coronal CT MinIP in identifying airway stenosis at ten specific sites and to determine observer agreement between the modalities regarding the degree of stenosis. Materials and methods: This retrospective cross-sectional study compared chest radiographs with standardized angled coronal CT MinIP in children with symptomatic lymphobronchial TB at ten predetermined airway locations. Chest radiographs were evaluated by one pediatric radiologist and CT MinIP reconstructions were independently interpreted by three readers. Sensitivity and specificity were calculated using CT MinIP as the gold standard. Stenosis was graded as 1 for mild (1–50%), 2 for moderate (51–75%), 3a for severe (76–99%), and 3b for total occlusion (100%). Agreement between the two modalities regarding severity of stenosis was calculated using the kappa coefficient for each affected site. Results: A total of 37 patients were included in the study. The median age of patients was 14.3 months (interquartile range 8.0–23.2). Three hundred and seventy individual bronchi (10 from each of the 37 patients) were evaluated for stenosis. Chest radiographs showed that 31 out of 37 (84%) patients had stenosis in at least one of ten evaluated sites, most commonly the left main bronchus and bronchus intermedius, and this was confirmed via CT MinIP. The gold standard (CT MinIP) demonstrated stenosis in at least one of ten sites in all 37 patients (100%). Left main bronchus stenosis was detected by chest radiography with a 92.9% sensitivity and 100% specificity. Sensitivity and specificity for bronchus intermedius stenosis were 80% and 75%, respectively. There was substantial agreement for grade of stenosis between chest radiographs and CT (kappa=0.67) for the left main bronchus and moderate agreement (kappa=0.58) for the bronchus intermedius. Severe stenosis was found in 78 bronchi on CT compared to 32 bronchi (Grade 3a: 9, Grade 3b: 23) on chest radiographs. Conclusion: The diagnosis of pulmonary TB in children continues to rely heavily on imaging, and we have shown that in young children, chest radiographs had a high sensitivity and specificity for detecting airway stenosis at certain anatomical sites, when adequately visualized, resulting from tuberculous lymph node compression at left main bronchus and bronchus intermedius. For most sites, the interobserver agreement was poor. Stenosis of the left main bronchus and bronchus intermedius should be the focus of chest radiograph interpretation and can assist both diagnosis and classification of patients for treatment. [ABSTRACT FROM AUTHOR]

This paper deals with some existence and uniqueness results for a class of deformable fractional differential equations. These problems encompassed nonlinear implicit fractional differential equations involving boundary conditions and various types of delays, including finite, infinite, and state-dependent delays. Our approach to proving the existence and uniqueness of solutions relied on the application of the Banach contraction principle and Schauder's fixed-point theorem. In the last section, we provide different examples to illustrate our obtained results. [ABSTRACT FROM AUTHOR]

Multistage inverters containing DC-DC converters are more common in grid-tied photovoltaic (PV) systems, because of the low DC voltage value provided by the PV generator, which requires a two-stage topology. The challenge in the latter case is to control the DC-link voltage with an accurate estimation of the current injected into the grid by PV system. In this paper, a two-stage grid-tied PV design based on a high-gain DC-DC converter and a 7 level packed U cells (7L-PUC) inverter, controlled by Finite-Control-Set Model Predictive Control (FCS-MPC) is presented, with the proposal of a novel model for controlling the DC-link voltage by considering system losses. The simulation and experimental results demonstrate the high effectiveness of the proposed control strategy in terms of power quality as well as response time and accuracy under changes in weather conditions and demonstrate the feasibility of the proposed system. [ABSTRACT FROM AUTHOR]

This article presents the effect of silt proportion on the hypoplastic parameters (exponent n, granular hardness hs, exponent α, and exponent β) used for numerical simulation, calculation of emax, and transitional fines content (Fct). Fifteen oedometer tests were carried out at various relative densities (RD = 30, 65, and 80%) to evaluate their effect on the compressibility parameters such as compression index Cc, secant oedometer modulus Esecant, and pre-consolidation pressure σ′p. Additionally, ten monotonic undrained triaxial tests were conducted at RD = 65% and RD = 80% to determine the value of the α parameter used in numerical simulation. The results obtained indicate that that the void ratio decreases with the increasing proportion of fine fraction up to 30% and further decreases with an additional increase of fines up to 40% for the three cases of relative densities (RD = 30, 65 and 80%). Additionally, it is shown from our results that the hypoplastic model is able to simulate soil behavior under undrained and oeodometer conditions. It was found that an increase in the α parameter leads to an increase in the dilatancy of the curves observed in the triaxial test. On the other hand, the parameters α and β seem to have no effect on the compressibility curves, and it was necessary to rely on their physical parameters. The transitional fines content (Fct) FC t FC t depends on the stress level and maximum void ratio, which are calculated from the parameters of the hypoplastic model (eio, hs, ps, n). [ABSTRACT FROM AUTHOR]

This paper deals with some existence results for a class of conformable implicit fractional differential equations with instantaneous impulses infinite delay in the context of b-metric spaces. The results are based on the ω - ψ -Geraghty type contraction and the fixed point theory. We illustrate our results by an example in the last section. [ABSTRACT FROM AUTHOR]

The study has focused on the development of bifunctional catalytic materials for the direct DME synthesis from CO2/H2. The industrial Cu/ZnO/Al2O3 is used as the copper based catalyst for the first step of the methanol synthesis from CO2/H2. It will be combined with hollow nano-ZSM-5 zeolites with mesoporous shell as the acid catalyst of the second step the methanol dehydration to DME. The bifunctional materials will be tested in the direct DME synthesis from CO2/H2 under the following conditions: T = 225 °C, p = 30 bar, H2/CO2 = 3. Under our reaction conditions, CO was not observed, only the DME majority product (77.5%) and CH3OH (22.5%) were obtained. [ABSTRACT FROM AUTHOR]

Radiation therapy is a treatment that uses particles to destroy cancer cells, stop their development and preserve the healthy organs around the tumour. A precise treatment requires the implementation of several processes, in particular, the determination of the correct ballistics, thus the effect of the particles on the deposited dose. Indeed, one of the most important steps in this evaluation is to calculate the deposited dose in a water phantom with resolution (20 × 20 × 30) cm3 using four therapeutic particles namely electromagnetic radiation "photons", negatively charged stable elementary particle "electrons", neutral particles "neutrons", and heavy elementary particle with a positive charge "protons" with nominal energies from 2 to 20 MeV with constant steps of 2 MeV were simulated in the first place. In the second place, we calculated the deposited dose of the protons beams for therapeutic energies ranging from 60 to 340 MeV with a beam of 100 000 particles produced by a primary radioactive source using the Monte Carlo simulation platform GEANT4. In our paper, we evaluate the effect of four therapeutic particles in the same environment assuring the accurate computation of delivered dose on the treatment plan and subtracting significant discrepancies in terms of deposited dose between particles. [ABSTRACT FROM AUTHOR]

Objective: A microbial fuel cell (MFC) has been conceived and constructed for the treatment of the sheep manure wastes and their conversion into clean sustainable renewable energy. The aim of the present investigation was to examine the performance of this bioelectrochemical device, in breaking down the organic matter (pollutant removal) and simultaneously producing electricity. Furthermore, the objective was to enhance the low electric energy by using an adequate amplification system. Results: So, the chemical oxygen demand (COD) removal was increased by 58.7% with the MFC running for 10 days. However, this technology faces practical barriers as it produces low electrical energy. A power management system was therefore elaborated in this respect. It included the MFC, operational amplifier (OA), solar photovoltaic panel and a boost DC/DC converter. The low voltage output obtained was thus increased substantially using the OA prior to its polarization by the solar photovoltaic module. The amplified voltage was sufficiently enough and in consequence, utilized to feed a light emitting diode. The low output voltage 0.5 V was simply harvested, successfully boosted up to approximately 2 V (i.e. 4 times higher) and finally harnessed as a power supply. Conclusions: The MFCs association shows the positive stacking effect successfully, when the cells were connected in parallel. This novel application is very interesting to utilize the natural bioenergy contained in wastes to supply small electronic devices. [ABSTRACT FROM AUTHOR]

This paper presents a study on Chlef sand to examine the effect of fines content (Fc), relative density (RD) and initial conditions on the compressibility behavior. The interpretation of the results is based on the concept of the intergranular voids ratio (es) and two hypoplastic parameters model Hs and n for calculation of the maximum voids ratio. The œdometric tests results made in the laboratory show that the fines content transition (Fct) of Chlef sand is in good agreement with the results published in the literature. The results obtained indicate that the higher value of fines fraction (Fc) in the sand cause an increase in the compressibility coefficient (Cc) and the granular compressibility coefficient (Cc-s). Moreover increasing the density from 65 to 80% decreased both coefficients (Cc) and (Cc-s). The samples prepared with the moist tamping method (w = 3%) have compressibility coefficients greater than samples prepared by the dry pluviation method (w = 0%). We have shown that the fines content transition (Fct) depends on the initial state of the samples (relative density, preparation method and maximum void ratio). Finally the granulometric characteristics (D10, D50 and Cu) have a significant effect on compression behavior. Nevertheless a good exponential correlation has been found between the compressibility coefficient (Cc), the granular compressibility coefficient (Cc-s) and the effective diameter (D10), the average diameter (D50) and the uniformity coefficient (Cu). [ABSTRACT FROM AUTHOR]

We consider in this work a bicriteria scheduling problem on two different parallel machines with a periodic preventive maintenance policy. The two objectives considered involve minimization of job rejection costs and weighted sum of completion times. They are handled through a lexicographic approach, due to a natural hierarchy among the two objectives in the applications considered. The main contributions of this paper are first to present a new problem relevant to practice, second, to develop a mixed-integer-linear-program model for the problem, and third, to introduce two generalizable tabu-search metaheuristics relying on different neighborhood structures and solution spaces. Computational results for 120 instances (generated from a real case) are reported to empirically demonstrate the effectiveness of the proposed metaheuristics. [ABSTRACT FROM AUTHOR]

In this study, the objective was to give more data related to the use of GATE (Geant4-based Application for Tomographic Emission) and Al2O3:C Optically Stimulated Luminescence (OSL) nanodots, as two alternative methods to estimate entrance surface dose (ESD) in mammography. First, ESD values were simulated with GATE and compared with values measured with Al2O3:C OSL nanodots and Solid State kV/dose Multisensor AGMS-M+ (Radcal,USA), using a standard breast phantom MTM100 (CIRS, USA). On the other hand, GATE simulations were also performed with PMMA slabs of different thicknesses (10 to 90 mm) and then compared with experimental values using AGMS-M+ detector. Results pointed to a maximum difference of 17%, between X-ray spectra simulated with GATE and those calculated with the IPEM report number 78 software, for this reason, the air kerma factor was calculated with GATE and IPEM and compared to the one measured by the AGMS-M+ detector. The ESD results indicate that GATE and Al2O3:C OSL nanodots values were compatible within 4% with those obtained with AGMS-M+. This work gives more data according to the use of GATE and Al2O3:C OSL nanodots to determine the ESD. Indeed, in the literature, there are few studies related to the use of GATE code and Al2O3:C OSL nanodots in mammography systems. [ABSTRACT FROM AUTHOR]

A quartz crystal microbalance (QCM) technique has been employed to tune friction at liquid–solid interfaces with tribotronic methods employing externally applied electric fields in both nanoparticle suspensions and ionic liquid systems. The setup consists of a QCM immersed in liquid containing electrically charged constituents whose sensing electrode faces a nearby counter electrode. An electric field perpendicular to the QCM surface is created when a potential is applied between the two electrodes, which allows the charged constituents in the surrounding liquid to be repositioned. QCM measurements are able to detect differences in friction under various field conditions, and thus detectably tune the friction in both nanoparticle and ionic liquid systems. The versatility and simplicity of QCM friction measurements render it an ideal tool for the rapidly expanding research area of tribotronics. [ABSTRACT FROM AUTHOR]

Purpose of Review: Cardiomyopathy with underlying left ventricular (LV) dysfunction is a heterogenous group of disorders that may be present with, and/or secondary to, coronary artery disease (CAD). The purpose of this review is to demonstrate, via case illustrations, the benefits offered by cardiac positron-emission tomography (PET) stress testing with coronary flow capacity (CFC) in the evaluation and treatment of patients with left ventricular (LV) dysfunction and CAD. Recent Findings: CFC, a metric that is increasing in prominence, represents the integration of several absolute perfusion metrics into clinical strata of CAD severity. Our prior work has demonstrated improvement in regional perfusion metrics as a result of revascularization to territories with severe reduction in CFC. Conversely, when CFC is adequate, there is no change in regional perfusion metrics following revascularization, despite angiographically severe stenosis. Furthermore, Gould et al. demonstrated decreased rates of myocardial infarction and death following revascularization of myocardium with severely reduced CFC, with no clinical benefit observed following revascularization of patients with preserved CFC. In a series of cases, we present pre-revascularization and post-revascularization PET scans with perfusion metrics in patients with LV dysfunction and CAD. In these examples, we demonstrate improvement in LV function and perfusion metrics following revascularization only in cases where baseline CFC is severely reduced. Summary: PET with CFC offers unique guidance regarding revascularization in patients with reduced LV function and CAD. [ABSTRACT FROM AUTHOR]

Due to the fast switching of the commutation cell in a motor drive system, high-frequency electromagnetic disturbances propagate through cables to reach the loads. Mismatched impedances lead to an overvoltage at the loads terminals. In order to study this EMI issue, accurate circuit models of power cables are required. In this context, this paper proposes two multi-conductor cable models. Our approach takes into consideration the frequency dependence of the cable per-unit-length parameters, the coupling between conductors and propagated induced phenomena. The power cables used in motor drive systems are characterized by their rotational symmetry. Thus, the complexity of the model is reduced by means of both a set of mathematical functions approximating the frequency behavior of the cable and using a modal domain-based transfer matrix. So, the VHDL-AMS frequency model can be easily deduced. Once the model is established, the simulation of any cable length becomes an easy task. The model is implemented in ANSYS Simplorer software. After that, the time domain model is built up based on the vector-fitting algorithm. In order to validate our proposal, a comparison of the common mode and the differential mode frequency responses of the reduced cable model with those of the well-known cascaded cell model and measurements found in the literature is performed. The results demonstrate the accuracy and the speed of our approach in the predefined frequency range. Also, a time-domain comparison between the frequency model and the time model is performed. The results obtained validate the two models. [ABSTRACT FROM AUTHOR]

We analyzed in detail the outcomes of eight patients with ventricular assist devices (VADs) and obesity who underwent laparoscopic sleeve gastrectomy (LSG) at a single heart transplant (HT) center. This comprehensive analysis included body mass index (BMI) trends from VAD implantation to the time of LSG; BMI and percentage of excess BMI lost during follow-up; adverse outcomes; and changes in echocardiographic parameters, fasting lipids, unplanned hospitalizations, and functional status. We also identified the patients who achieved the following outcomes: listing for HT, HT, 50% excess BMI loss, and BMI < 35 kg/m2. Laparoscopic sleeve gastrectomy seems to be a reasonable and effective intervention to help patients with VADs and obesity to decrease excess BMI and become candidates for HT. [ABSTRACT FROM AUTHOR]

This work offers a simple and efficient model predictive voltage control strategy with a two-step prediction for improved output voltage control of single-phase inverter used for stand-alone renewable energy systems. The single-phase inverter with output LC filter is used to provide a sinusoidal output voltage, regardless of the arbitrary consumer load profiles. The suggested control algorithm uses the discrete-time model of the inverter and LC filter for two-step prediction of the output voltage for each possible switching state. Then, the control algorithm selects the switching state which minimizes the error between the output voltage and its reference without using any inner controllers or modulators. An accurate extrapolation methodology with reduced computational burden is used to predict the dynamic changes in the output voltage reference. The switching frequency reduction is also attained by considering a simple constraint in the suggested algorithm. Simulation results are presented to verify the feasibility and excellent performance of the suggested controller under linear and nonlinear load conditions, compared to a conventional voltage control strategy based on PI regulators and PWM. Furthermore, experimental tests using a dSPACE system with DS1104 controller have been done to confirm the simulations results. [ABSTRACT FROM AUTHOR]

We studied the process of energy release of the confined X2.2 flare, which occurred September 6, 2017 in the active region NOAA 12673. The magnetic reconnection rate and reconnection fluxes were obtained from chromospheric data (SDO/AIA 1600 Å) and magnetograms of the photospheric field (SDO/HMI). The time profiles of the magnetic reconnection rate and microwave emission obtained by the radioastronomical diagnostic complex of solar activity of the Crimean Astrophysical Observatory, Russian Academy of Sciences (KRIM) demonstrate good agreement. This suggests that the magnetic reconnection rate plays an important part in the energy release in flares and in the acceleration of nonthermal electrons with formation of microwave emission. The morphology of the flare radio source in low-frequency emission has been studied. The low-frequency slope of the flux density spectrum is 1.2, which indicates a spatial inhomogeneity of the source. The area of such a source increases with a decrease in frequency. [ABSTRACT FROM AUTHOR]

This paper tackles the single machine scheduling problem with periodic preventive maintenance in order to minimize the weighted sum of completion times. This criterion is certainly less studied than the makespan but it remains nonetheless interesting on the theoretical and practical levels. Indeed, the weights can quantify the holding cost per unit of time of the products to transform. Thus, this criterion can represent the global holding cost. This problem is proved to be NP-hard and a mixed integer linear programming formulation is proposed to solve small size instances of the problem. To solve large instances, we proposed three properties for this problem which generalize already existing works. These properties have been of great use in designing efficient heuristics capable of solving instances with up to 1000 jobs. To evaluate the performances of the proposed heuristics, lower bounds based on special cases of the problem are provided. Computational experiments show that the average percentage error of the best heuristic is less than 10%. [ABSTRACT FROM AUTHOR]

We analyzed the dynamics of the reconnection and energy release processes of the X2.2 and X9.3 flares that occurred on September 6, 2017 in the active region NOAA 12673. We used SDO/AIA 1600 Å images together with SDO/HMI magnetograms. As a proxy for the flare energy release rate, we used the KRIM and RSTN microwave time profiles, GOES soft X-rays and its time derivative. Assuming that the chromospheric flare ribbons are located at the footpoints of magnetic field lines reconnecting in the corona and that the magnetic flux is conserved from the photosphere to the corona, we obtained magnetic reconnection fluxes and rates of its change. The cumulative positive and negative magnetic fluxes involved in the reconnection process were balanced. Temporal correlations are found between the calculated reconnection rate and the observed microwave emissions from for both events. An analysis of the total cumulative magnetic flux and SXR fluence of events showed that the magnitude of the magnetic flux involved in the reconnection process was greater in more energetic events and less in weaker ones. [ABSTRACT FROM AUTHOR]

Recent studies identified chronic leptomeningeal enhancement (LME) in late-acquired FLAIR sequences in secondary progressive (SP) multiple sclerosis (MS). These LMEs correlate with focal cortical inflammation and demyelination observed by pathology, which are supposed to drive long-term cortical atrophy. We report a spontaneously remitting meningeal uptake in a patient suffering from SP MS. No cortical lesion was visible on FLAIR or DIR sequences, but the rate of cortical atrophy was higher in this area. This case suggests that conventional 3-T MRI, by contrary to white matter lesions, may be amnesic with regard to the potential burden of previous regressive meningeal lesions. Moreover, T1-enhanced sequences underscore the real inflammatory activity. LME could be more than passive markers of SP MS, but is also directly responsible for focal cortical atrophy and could be an early manifestation of cortical lesions. [ABSTRACT FROM AUTHOR]

In radiotherapy applications, Monte Carlo (MC) simulation for dose calculations is well acknowledged for its accuracy in predicting dose deposition in the patient. The full modeling of a high-energy photon beam from Varian Clinac 2100C 18 MV medical linear accelerator is presented here by using the GATE/GEANT4 Monte Carlo codes. To evaluate dose distributions associated with the simulated linac head model, dosimetric quantities including the Percentage Depth Dose (PDD), transverse dose profiles, and a set of beam-quality indicators were measured and calculated in a water phantom for square field sizes of cm and cm . Simulations accuracy was validated through Gamma Index analysis using different acceptance criteria within 2 2 mm, 3 2 mm, 2 3 mm, and 3 3 mm. In terms of Gamma Index comparison, good agreements were found between the calculated and measured dose distributions for all field sizes. The differences between simulation and measurement of beam quality indicators were smaller than 2 . [ABSTRACT FROM AUTHOR]

One of the most significant problems in image and vision applications is the efficient representation of a target image containing a large amount of data with high complexity. The ability to analyze high dimensional signals in a lower dimension without losing their information, has been crucial in the field of image processing. This paper proposes an approach to 3D face recognition using dimensionality reduction based on deformed circular curves, on the shortest geodesic distances, and on the properties of the Fourier Transform. Measured geodesic distances information generates a matrix whose entities are geodesic distances between the reference point and an arbitrary point on a 3D object, and an one-dimensional vector is generated by reshaping the matrix without losing the original properties of the target object. Following the property of the Fourier Transform, symmetry of the magnitude response, the original signal can be analyzed in the lower dimensional space without loss of inherent characteristics. This paper mainly deal with the efficient representation and recognition algorithm using deformed circular curves and the simulation shows promising result for recognition of geometric face information. [ABSTRACT FROM AUTHOR]

This work relates to the study and characterization of the CTDI (Computed Tomography Dose Index) for the 16 slices CT scanner. The CTDI has been simulated with the Monte Carlo code GATE for PMMA (polymethylmethacrylate) digital phantoms of various diameters (1–50 cm) at various kVp (80, 110, 130) and mAs (100, 200, 300, 400 mAs) levels. After using a High-Performance Computing (HPC) station, a good agreement was observed (less than 1.18% for head phantom and 1.85% for body phantom for all applied voltages) between simulations and experimental measurements with standard PMMA phantoms. Results of simulations demonstrated the following. Firstly, GATE is an adapted tool to estimate CTDI values and can be used to optimize CT parameters in clinical applications. Secondly, Monte Carlo simulation may be able to estimate the absorbed dose when the CTDI method has limitations (use of homogeneous standards cylindrical phantom, the dose measurement in air not in tissue). [ABSTRACT FROM AUTHOR]

This paper focuses on the control of large-scale grid-connected photovoltaic system. The proposed system is composed of two conversion stages: the first stage contains four PV arrays, each one connected to an individual DC/DC converter (boost converter), while the second stage is a five-level neutral point clamped (NPC) inverter tied to the grid. Each DC-link capacitor input of the NPC inverter is connected to the output of the DC/DC boost converter. In order to enhance the energy harvesting capability of the proposed system, different controllers based on finite-set model predictive control (FS-MPC) are developed and presented. A fast voltage-oriented maximum power point tracking performed by FS-MP current controller (FS-MPCC) is investigated and applied for each boost converter to maximize the produced power from each PV array. Furthermore, a FS-MPC algorithm is proposed to control the centralized five-level NPC inverter. The purposes of the developed controllers are: track the MPP rapidly and accurately under sudden irradiation changes, ensure the balance of the four DC-link capacitor voltages whatever the difference between the extracted powers from each PV system unit, inject the reactive power demanded by the grid operator and also minimize the switching frequency of the five-level NPC inverter. The results obtained through MATLAB/Simulink and Simpower toolbox packages prove that the proposed control scheme provides better performance in comparison with conventional control scheme. Moreover, a high grid current quality and perfect DC-link capacitor voltages balancing are ensured under contrast of extract powers from each PV system. [ABSTRACT FROM AUTHOR]

Adolescents are exposed to various stressors that may increase the risk for substance use. Due to the detrimental, and potentially long-lasting, effects related to substance use, it is necessary to explore more optimal coping strategies. This study explored the association between substance use and stress among male and female high school students in relation to spirituality as a moderator. To examine these relationships, the study used cross-sectional data collected from 27,874 high school students (Male = 50.7%, Female = 49.3%) across 58 high schools in Maryland that included an ethnically diverse sample (49% Caucasian, 30% African American) with an average age of 16 years old. Bivariate results showed differences in substance use, stress, and spirituality between male and female students. Higher rates of substance use were generally found among male students compared to female students; rates tended to be higher among female students for stress and spirituality compared to their male counterparts. Multilevel analyses indicated a positive association between stress and substance use among male and female students after adjusting for demographic and school-level factors. Both male and female students who reported turning to spiritual beliefs when experiencing problems were less likely to use substances. However, the interaction between stress and spirituality was significant for males only. These findings suggest that stress may increase the propensity for substance use and that spirituality might be a viable coping mechanism useful for helping high school students adapt to stressful circumstances and situations. [ABSTRACT FROM AUTHOR]

Quartz crystal microbalance (QCM) and electrical resistivity measurements were carried out on the systems Xe/Ag and N2/Pb to determine the relative contributions of electronic and phonon dissipative mechanisms to sliding friction. Results show significantly differing proportions of electronic friction in the two systems. [ABSTRACT FROM AUTHOR]

In this paper, undrained triaxial compression tests were performed on specimens obtained in Oued Rass sand (Chlef, Algeria). The objective of this study is to investigate the effects of specimen deposition methods, the initial density, and the confining pressure on the undrained behavior of this sand. The test results show that the initial confining pressure and the relative density affected, in a significant manner, the resistance to liquefaction. However, it increases with confining pressure and relative density. The results also show that the specimens prepared by dry deposition method have a greater resistance to liquefaction than those prepared by moist tamping. A nondestructive comparative analysis of the deposits by X-ray microtomography carried out at the granular scale made it possible to characterize more precisely the difference of the obtained structures for the two deposition modes. [ABSTRACT FROM AUTHOR]

Copyright of Qualitas Plantarum et Materiae Vegetabiles is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Electrical Contact Resistance (ECR) measurements are reported for RF micro-electromechanical switches with Au-RuO contacts, situated within an ultrahigh vacuum system equipped with in situ oxygen plasma cleaning capabilities. Two studies are reported, each involving a comparison of the ECR in vacuum and nitrogen environments for measurements performed immediately after cleaning. The first study reports measurements of initial resistance (resistance measured upon first time closure) versus pressure as dodecane gas is admitted to the chamber. A significant increase is observed at pressures in vacuum as low as 10 torr, (P/P < 10) consistent with earlier reports involving repetitive cycling of macroscopic switches in partial pressures of hydrocarbons in nitrogen. Somewhat unexpectedly, however, the resistance only doubles, even for pressures sufficiently high as to result in full monolayer condensation. In a second study, switch lifetimes in vacuum (10-10 torr) and nitrogen gas environments are compared, for switches operated immediately afterward, or alternatively left open for a number of days before operation. Although it was expected that vacuum would reduce and/or prevent contamination of the electrical contact surfaces, no enhancement or extension of lifetime was observed: Continuous operation of a switch in a nitrogen environment immediately after plasma cleaning was in fact the only procedure observed to indefinitely prolong device lifetime. The results suggest that (1) Hydrocarbon reaction products, but not mobile physisorbed hydrocarbons themselves, are responsible for increasing ECR by orders of magnitude and (2) Repetitive cycling motion of a clean switch in nitrogen inhibits formation of physisorbed hydrocarbon contaminants on the contacts, while vacuum levels far superior to 10 torr are required to prevent contamination. [ABSTRACT FROM AUTHOR]

Abstract  We describe herein how a quartz crystal microbalance (QCM) can be used to measure wetting behavior and sliding friction levels of adsorbed films and a brief summary of the status of the fundamental energy dissipative mechanisms that give rise to friction in these systems. The relation between sliding friction values, diffusion coefficients, and film lubricity is next described. Finally, as a specific case example, QCM measurements of the uptake and sliding friction levels of adsorbed ethanol, trifluoroethanol (TFE) and pentanol films on silicon, aluminum and perfluorodecyl-trichlorosilane (PFTS) treated substrates are reported and analyzed. These systems are of interest to the silicon microelectromechanical systems (MEMS) community, whose progress has been limited by tribological issues. [ABSTRACT FROM AUTHOR]

Recent observations of superconductivity-dependent friction in nitrogen films adsorbed on lead substrates have inspired a number of theoretical and experimental efforts to understand the origins of this phenomenon. The status of these efforts is discussed, focussing on the role of electronic contributions to friction. [ABSTRACT FROM AUTHOR]