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The grading of gemstones is currently a manual procedure performed by gemologists. A popular approach uses reference stones, where those are visually inspected by specialists that decide which one of the available reference stone is the most similar to the inspected stone. This procedure is very subjective as different specialists may end up with different grading choices. This work proposes a complete framework that entails the image acquisition and goes up to the final stone categorization. The proposal is able to automate the entire process apart from including the stone in the created chamber for the image acquisition. It discards the subjective decisions made by specialists. This is the first work to propose a machine learning approach coupled with image processing techniques for emerald grading. The proposed framework achieves 98% of accuracy (correctly categorized stones), outperforming a deep learning approach. Furthermore, we also create and publish the used dataset that contains 192 images of emerald stones along with their extracted and pre-processed features. [ABSTRACT FROM AUTHOR]

We investigated the photoconductivity effect in n-type PbTe/Pb0.88Eu0.12Te quantum wells for a temperature range of 300–10K using infrared light. The measurements revealed that at high temperatures, the photoresponse has small amplitude. As temperature decreases to T~75 K, however, the photoconductivity amplitude increases reaching a maximum value 10 times higher than the original value before illumination. From Hall measurements performed under dark and light conditions, we show that this effect is a result of the carrier concentration increase under illumination. Unexpectedly, for further reduction of temperature, the amplitude starts to decrease again. The electrical resistance profiles indicate that the transport occurs through barriers and the well that behave as two parallel channels. For temperatures below 75 K, transport is more effective in the quantum well, where the signal reduction can be associated with the electron-electron scattering due to the increase in the carrier concentration that occurs under illumination. We also used the random potential model to explain the origin of the persistent effect observed in the photoconductivity curves. [ABSTRACT FROM AUTHOR]

Focuses on a study which presented the application of roots searching for fixing nulls with phase-only control in equispaced linear arrays. Discussion on simulated annealing technique; Measurement of null depth; Methodology and results.

Focuses on a study which explored the development of mathematical model for array pattern synthesis in near-zone scatters of three-dimensional vectors. Discussion on simulated annealing technique; Polarization of electromagnetic scattering; Information on simulation process; Methodology and results.

We wanted to use biomechanical testing in a cadaveric model to compare the Brostrom repair, the Watson-Jones reconstruction, and a new anatomic reconstruction method. Eight specimens were held in a specially designed testing apparatus in which the ankle position (dorsiflexion-plantar flexion and supination-pronation) could be varied in a controlled manner. Testing was done with intact ligaments and was repeated after sectioning of the anterior talofibular ligament and the calcaneofibular ligament and after a Brostrom repair, a Watson-Jones reconstruction, and a new anatomic reconstruction were performed. An anterior drawer test was performed using an anterior translating force of 10 to 50 N, and a talar tilt test was performed using a supination torque of 1.1 to 3.4 N-m. The forces in the anterior talofibular ligament and calcaneofibular ligament were measured with buckle transducers, and tibiotalar motion and total ankle joint motion were measured with an instrumented spatial linkage. The increase in ankle joint laxity observed after sectioning of both the anterior talofibular and calcaneofibular ligaments was significantly reduced by the three reconstructive techniques, although not always to the level of the intact ankle. Joint motion was restricted after the Watson-Jones procedure compared with that in the intact ankle. Unlike the Watson-Jones procedure, the ligament or graft force patterns observed during loading after the Brostrom repair and the new anatomic technique resembled those observed in the intact ankle. [ABSTRACT FROM AUTHOR]

Because of the good initial fixation strength of interference screws used in anterior cruciate ligament reconstruction, metal interference screws have become the standard method for fixation of bone-patellar tendon-bone grafts. To avoid some of the complications with metal screws, a bioabsorbable interference screw was developed. Data on fixation strength in older human cadavers indicate a similar failure strength between bioabsorbable and metal screws. We studied the failure mechanisms, insertion torques, and fixation strengths of absorbable and metal interference screws in cadaveric knees from young and middle-aged donors. With identical gap and screw size, the mean insertion torque for the metal screws (mean, 1.5 N-m; SD, 0.8) was significantly higher than for the absorbable screws (mean, 0.3 N-m; SD, 0.19). The mean failure load for the metal screws (mean 640 N; SD, 201) was also significantly higher than for the absorbable screws (mean, 418 N; SD, 118). [ABSTRACT FROM AUTHOR]

The widely used first-order polynomial representation of the voltage reflection coefficient in multisection quarter-wavelength transformers is assumed. The roots of this polynomial are displaced iteratively to obtain, through the simulated annealing technique, low variability between the characteristic impedances of adjacent transformers. Besides, for each problem configuration, the bandwidth is maintained close to its maximum possible value. An example is presented showing a decrease in the characteristic impedance variability of the transformers. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 194–196, 1999. [ABSTRACT FROM AUTHOR]

Contents A 6-year-old female Alaska Malamute dog was presented for evaluation of abdominal enlargement referred by a local veterinarian. On the history, the owner complained of chronic abdominal enlargement initiated more than 4 months ago, reduced appetite, occasional vomiting and general dullness. He also complained of greenish mucous intermittent vaginal discharge starting 10 days ago. The bitch was chronically treated with medroxiprogesterone acetate. A laparatomy was performed and fluid in the abdomen was found and aspirated during the surgery. Also a very fluid-filled distended uterus and a mass in the distal part of the left uterine horn were found. The mass was encapsulated by the omentum, but areas of necrosis and calcification were identified. Histopathological diagnosis was endometrial adenocarcinoma. [ABSTRACT FROM AUTHOR]

A new antenna concept—the multi-radial travelling wave line antenna — that achieves a broadband conical radiation pattern suitable for use in multiple C-band wireless computer networks is presented. [ABSTRACT FROM AUTHOR]

A novel hybrid approach to the power synthesis of mask-constrained shaped beams by means of concentric-ring isophoric arrays is presented. The basis of this procedure is to use the complex aperture distribution obtained by Elliott–Stern method as a starting point of an innovative algorithm that combines a classical density tapering method with a simulated annealing one. The proposed technique allows to outperform the previous procedures. [ABSTRACT FROM AUTHOR]

For the synthesis of radiation patterns using antenna arrays with thousands of elements, the combination of direct methods with non-stochastic optimization can be more efficient than stochastic optimization. Here we describe an efficient method for the synthesis of footprint patterns that combines Hankel transformation with Fourier analysis following angle-dependent homothesis (i.e., radial stretching and/or shrinking) of an axisymmetric Elliott-Stern pattern for a circular aperture. The new method can in principle be applied to arrays of radiating elements with arbitrary locations and element patterns. [ABSTRACT FROM AUTHOR]

Abstract: Sample preparation has witnessed transformation in recent years, with the main efforts focused on acceleration, simplification, miniaturization and automation of the operations involved. Ultrasound is a clean, efficient energy that has dramatically improved many sample-preparation protocols. The unique conditions provided by acoustic cavitation have enhanced solid-sample pretreatments (e.g., digestion, dissolution and extraction), which are typically applied prior to detection. At present, awareness of green aspects has led many analytical chemists to consider key indicators (e.g., operation time, safety, volume/concentration of solvents and energy consumption) when developing new sample-preparation methods. This overview tackles the main applications of ultrasound for pretreatment of solid samples and some liquid samples with a complex matrix (e.g., wastewater) in the context of green analytical chemistry. [Copyright &y& Elsevier]

The problem of synthesizing a linear array generating a shaped beam pattern with M filled nulls has 2M alternative solutions. The sensitivity of the performance to errors in element position, excitation phase or amplitude of the solutions provided by the synthesis of a flat-topped beam pattern using an array of 16 isotropic elements spaced λ/2 was analysed. [ABSTRACT FROM AUTHOR]

Given a linear antenna array with an excitation distribution affording an optimal sum pattern, subarray weighting allows the same array also to generate a difference pattern, with minimal alteration of the signal feed circuitry. In this approach, it is not necessary to consider the whole array for subarraying: We report that the required feeding networks can be further simplified by keeping the elements at the edges of the array with common excitations for both sum and difference patterns. [ABSTRACT FROM AUTHOR]

The objective of this work is to introduce and numerically solve a mathematical model for unsteady thermoelectrical behavior of an electric arc electrode. The electrode is composed of several materials and one of them suffers a change of state during operation. Thermoelectric parameters depend on the temperature in each material. The volumetric heat source is the Joule effect. The mathematical model leads to a coupled non-linear system of partial differential equations. The axisymmetry of the domain allows us to simplify the problem when it is written in cylindrical coordinates. We use an implicit method for time discretization and a standard finite element method for space discretization. Numerical results corresponding to the simulation of a real industrial situation are given. [Copyright &y& Elsevier]

Saline and sodic soils pose major agronomic problems in arid and semiarid regions. Marsh soils in the Guadalquivir Valley are representative of saline and sodic soils in estuarine environments, and are frequently reclaimed for agricultural use. Flooding affects the nature of P sorbent surfaces in soils; it increases the proportion of poorly crystalline Fe oxides relative to highly crystalline ones, which predominate in the calcareous soils typical of the region. Poorly crystalline Fe oxides and silicate clays appear to be the main P sorbent surfaces in these soils. Carbonates seemingly have adverse effects on short-term P sorption, probably as a result of Fe oxides being partly occluded in them. Salinity, sodicity, and soil amendments can affect P forms and P dynamics in soil. Olsen P is negatively correlated (r = -0.81**) with the Na/Ca mole ratio, and positively correlated with sulfate concentration in the 1:1 extract (r = 0.75**), indicating that soils that receive large amounts of Ca amendment (e.g., phosphogypsum) exhibit increased contents in available P. The increased Ca saturation as a result of the amendment raises the short-term sorption capacity of sorbent surfaces and results in a major contribution of Ca phosphate precipitation to long-term P sorption, as suggests the relationship between d (exponent of time in the modified Freundlich equation) and the Na/Ca mole ratio in the 1:1 extract (Y = 0.26 X-[sup 0.38],R[sup 2] = 0.66**). Resins can simulate P release to a solution with a near-zero P concentration and hence provide information about the P release potential of soil, which is agronomically and environmentally relevant. The release potential of a soil increases with increasing degree of P enrichment. Released P appears to be related to P fractions containing adsorbed P and the more soluble (citratebicarbonate extractable) Ca phosphates, and can be estimated by using a single-extraction method (Olsen P). [ABSTRACT FROM AUTHOR]

Pencil beams may be synthesized for arrays of concentric rings of radiating elements by fitting the field pattern to that of a Taylor pattern for a circular aperture of the same radius. Nonexcitation blockage suppresses inner rings. Here we examine whether this needs to be taken into account in the synthesis procedure. [ABSTRACT FROM PUBLISHER]

The complexity of antenna array feed networks can be reduced by reducing the number of radiating elements and having the remainder illuminate an auxiliary array of parasitic elements. The performance of such antennas can be optimized by optimization of their geometry. Here we consider parasitic linear arrays of dipoles illuminated by smaller uniformly fed linear arrays so as to generate low-sidelobe sum patterns with good directivity. The results of a FEKO simulation validating the accuracy of the coupling model are presented, and the influence of the relative numbers of active and parasitic dipoles is discussed. [ABSTRACT FROM AUTHOR]

This work presents the results of magnetotransport measurements performed on a 156 nm-thick Bi2Te3 epitaxial film in the temperature range of 1.9–300 K, showing Shubnikov–de Haas oscillations for temperatures below 50 K. A detailed analysis of oscillations as a function of temperature provides the main transport parameters, including the Landé g-factor and cyclotronic masses. A systematic analysis of fast Fourier transform, performed on the oscillations, indicates that the origin of the oscillation pattern is not related to the topological surface states but from the Rashba splitting of the Bi2Te3 Fermi surface. [ABSTRACT FROM AUTHOR]

In this work, we present the results of photoconductivity measurements performed in the temperature range of 12 K–300 K on a 150 nm-thick Bi2Te3 film grown by molecular beam epitaxy on a (111) BaF2 substrate. A transition from negative to positive photoconductivity is found to occur around 125 K. Resistivity and Hall data measured under light and dark conditions qualitatively elucidate the observed phenomena. The Arrhenius plot of recombination times obtained from photoconductivity decay curves measured at different temperatures gives the activation energy associated with the bulk trap level. Using this activation energy as the effective trap potential, we calculated the generation and recombination rates as a function of temperature. The analysis provides a quantitative explanation that predicts the transition effect observed in the experiment. No evidence of contribution from surface states is found from the magnetoresistance curves measured at low temperatures. [ABSTRACT FROM AUTHOR]

Interest in uniformly illuminated (isophoric) density-tapered planar antenna arrays has recently revived. For arrays consisting of concentric rings of elements, we present a nonstochastic algorithm that calculates ring radii for generation of pencil beams without the need for prior specification of the number of rings. Use of the algorithm is illustrated by application to multibeam coverage of the Earth. The use of its results as the starting point of a stochastic optimization has led to complete solution of a hitherto recalcitrant synthesis problem. [ABSTRACT FROM AUTHOR]

A simple method for synthesising low-sidelobe sum and difference patterns with a common aperture zone is presented. Such a method is based on the perturbation of the Bayliss roots by means of the simulated annealing technique. The appropriate discretisation of the resulting continuous apertures to a linear array would lead to a simplification of its feeding network, mainly due to the above-mentioned shared portion. A complete study is presented to show the scope of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, a technique to minimize the variability of the scattering coefficients in multihole directional couplers is shown. The technique also controls important features of the frequency response like bandwidth and minimum directivity. Several examples are presented to show the method's capabilities. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 412–413, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10622 [ABSTRACT FROM AUTHOR]

The aim of this study was to compare some depressors of the central nervous system combined with ketamine in order to find an adequate scombination for anaesthesia in mice, coupled with a simple, easy to use and reliable method. Forty Swiss OF-1 mice (Mus musculus), 20 females and 20 males with a body weight from 35 to 45 g aged from 12 to 16 weeks, were used to evaluate one of the following central nervous system depressors (CNSD): acepromazine (5 mg/kg), diazepam (5 mg/kg), medetomidine (1 mg/kg), midazolam (5 mg/kg) and xylazine (10 mg/kg) combined with the dissociative anaesthetic ketamine (100 mg/kg) by the intraperitoneal route. Different parameters were evaluated at regular intervals to assess the depth of anaesthesia (time of induction, time of loss and recovery of pedal withdrawal reflex, time of recovery from the anaesthesia), and respiratory and heart rate and oxygen saturation. Most of the assessment times and physiological parameters were exhibited earlier in females than in males but, in most cases, these differences were not significant. The diazepam combination resulted in death in half of the male group. Significant differences for the combination comparison were found for induction, pedal withdrawal reflex and recovery from anaesthesia, as well as for respiratory and heart rate and oxygen saturation. The best results for mice of both genders, i.e. induction, maintenance and recovery from anaesthesia were more stable with α2-agonists than with other combinations (benzodiazepines or acepromazine), which did not reach a good anaesthetic level, that is, an adequate anaesthetic plane with an absence of the pedal withdrawal reflex and the maintenance of stable vital constants. [ABSTRACT FROM AUTHOR]

This study investigated the effects of microwave radiation on the PVN of the hypothalamus, extracted from rat brains. Expression of c-Fos was used to study the pattern of cellular activation in rats exposed once or repeatedly (ten times in 2 weeks) to 2.45 GHz radiation in a GTEM cell. The power intensities used were 3 and 12 W and the Finite Difference Time Domain calculation was used to determine the specific absorption rate (SAR). High SAR triggered an increase of the c-Fos marker 90 min or 24 h after radiation, and low SAR resulted in c-Fos counts higher than in control rats after 24 h. Repeated irradiation at 3 W increased cellular activation of PVN by more than 100% compared to animals subjected to acute irradiation and to repeated non-radiated repeated session control animals. The results suggest that PVN is sensitive to 2.45 GHz microwave radiation at non-thermal SAR levels. [ABSTRACT FROM AUTHOR]

A speciation method based on Chelex-100 titration in combination with electrothermal-atomic absorption spectrometry has been developed to study the distribution of Pb among different fractions in coastal seawater. The method allows an accurate determination of total Pb, thereby avoiding the effect of the saline matrix. Additionally, the distribution patterns of Pb among species with different lability can be established in seawater as a function of pH. Four Pb fractions have been obtained in a model seawater and two seawater samples from Ria de Vigo (NE Atlantic ocean), i.e. free Pb ion, inorganic Pb fraction, organic Pb fraction and inert Pb fraction. The inert and labile organic Pb fractions dominate at natural pH (≈8). Complexation mechanisms of Pb were investigated from the sorption curves of lead on Chelex-100 according to the Gibbs - Donnan model. Three complexes were formed, PbL, PbL2 and Pb(HL)2 with the following intrinsic complexation constants log β(1np) = -3.25, -10.10 and -1.98, respectively. The formation of the complex PbL is negligible in all range of pH studied, while the complex Pb(HL)2 predominates up to pH 4 and PbL2 from pH 4. [ABSTRACT FROM AUTHOR]

Abstract: Ultrasound-assisted extraction combined with electrothermal-atomic absorption spectrometry has been applied to the determination of silver and gold at μgg−1 levels in different environmental samples such as soil, sediment, fly ash and industrial sludge. Two different extraction systems have been tried, i.e. acid mixtures (HCl, HF, and HNO3) and thiourea in diluted H2SO4 medium. In both cases, an efficient cup-horn sonoreactor was used as ultrasonic device to accelerate the extraction process. This ultrasonic processor allows the use of any extractant including HF and simultaneous treatment of up to six samples. Recovery ranged from 81% to 107% for silver, and from 91% to 105% for gold. Optimal acid mixtures were 25% v/v HNO3 +25% v/v HF for Ag and 25% v/v HNO3 +25% v/v HCl for Au. The thiourea method required 0.6% m/v thiourea+2% v/v H2SO4. The latter method was considered advantageous since efficient Au and Ag extractions were obtained in a short time, and moreover, wastes generated were less harmful to the environment. Limits of detection for Ag and Au were 0.012 and 0.050μgg−1, respectively. Repeatability expressed as relative standard deviation ranged from 2 to 10% for both metals. Both extraction methods were applied to the determination of Au and Ag in sediments and soils located at different sampling points from Galicia (Spain). [ABSTRACT FROM AUTHOR]

A simple and fast method to accelerate the global optimization approaches used in array thinning is described. This method tabulates the contribution of every array element to the far-field pattern in order to improve the numerical efficiency of the optimization algorithm employed. Experiments using our proposal alongside with a genetic algorithm reduce the search computation time about 90%. Simulation results for both linear and planar arrays are shown. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the determination of rare earth elements (REEs), i.e. Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in marine biological tissues by inductively coupled-mass spectrometry (ICP-MS) after a sample preparation method based on ultrasound-assisted extraction (UAE) is described. The suitability of the extracts for ICP-MS measurements was evaluated. For that, studies were focused on the following issues: (i) use of clean up of extracts with a C18 cartridge for non-polar solid phase extraction; (ii) use of different internal standards; (iii) signal drift caused by changes in the nebulization efficiency and salt deposition on the cones during the analysis. The signal drift produced by direct introduction of biological extracts in the instrument was evaluated using a calibration verification standard for bracketing (standard-sample bracketing, SSB) and cumulative sum (CUSUM) control charts. Parameters influencing extraction such as extractant composition, mass-to-volume ratio, particle size, sonication time and sonication amplitude were optimized. Diluted single acids (HNO3 and HCl) and mixtures (HNO3 +HCl) were evaluated for improving the extraction efficiency. Quantitative recoveries for REEs were achieved using 5mL of 3% (v/v) HNO3 +2% (v/v) HCl, particle size <200μm, 3min of sonication time and 50% of sonication amplitude. Precision, expressed as relative standard deviation from three independent extractions, ranged from 0.1 to 8%. In general, LODs were improved by a factor of 5 in comparison with those obtained after microwave-assisted digestion (MAD). The accuracy of the method was evaluated using the CRM BCR-668 (mussel tissue). Different seafood samples of common consumption were analyzed by ICP-MS after UAE and MAD. [ABSTRACT FROM AUTHOR]

A common method of antenna array synthesis uses least-squares approximation to fit the radiation pattern of the array to a set of samples of an ideal desired pattern Fid. However, it has long been known that discontinuities in Fid prevent close approximation, and that sampling a target pattern Ftar that approximates Fid can afford better results. Here we show, for the case of circular planar arrays, that an appropriate target pattern can be obtained by modification of a Taylor pattern for a circular aperture. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this work is to present and numerically solve a mathematical model for the thermal behavior of a casting ladle devoted to purification of silicon. A nonlinear and nonlocal boundary condition is considered for radiative heat transfer in an inner closed cavity of the domain. We also propose a numerical approximation using a finite element method. An iterative algorithm and numerical results are presented. [Copyright &y& Elsevier]

In 1997, an outbreak of human tularemia associated with hare-hunting in central Spain affected 585 patients. We describe the identification of Francisella tularensis biovar palaearctica in a second outbreak of ulceroglandular tularemia associated with crayfish (Procambarus clarkii) fishing in a contaminated freshwater stream distant from the hare-associated outbreak. The second outbreak occurred 1 year after the first. [ABSTRACT FROM AUTHOR]

A survey of 150 rice farmers in three municipalities of the Ifugao Rice Terraces, Philippines, carried out in June 1998, aimed to assess the farmers' knowledge, attitudes, and practices of rice crop and pest management. The survey revealed that: 54% of the farmers fall within a narrow age range (31-50 years), the majority having 11-30 years of rice farming experience; they are of average literacy; and they have large households. Non-farm activity such as woodcarving was the most common source of additional income. The majority of farmers planted a single crop of rice per year and followed traditional cultivation practices. Major rice crop production constraints were drought due to the El Nino phenomenon and insufficient irrigation infrastructure. Zinc deficiency was widespread. Major, non-insect pests known to farmers were earthworms, rats, golden apple snails, and house sparrows. These pests damage either the rice plant or the terrace wall. Earthworm damage to the terrace wall is most obvious. Farmers had very little exposure to integrated pest management and new rice technologies. [ABSTRACT FROM AUTHOR]

Examines the occurrence of pemphigus after using cilazapril, a non-thiol-containing angiotensin-converting enzyme (ACE) inhibitor. Definition of pemphigus; Performance of skin biopsy; Use of oral prednisone as treatment.

The precision with which footprint patterns produced by planar arrays conform to the desired shapes is dramatically improved by a two-stage array synthesis process in which optimization of the array boundary is follows by optimization of element excitations. The procedure is illustrated by synthesis of arrays with real and complex excitations radiating a rectangular footprint with a 2:1 aspect ratio. [ABSTRACT FROM AUTHOR]

We investigated the photoconductivity effect in p-type Pb1-xEuxTe films for x=0.01, 0.02, 0.03, 0.05, and 0.06 at T=300K. The measurements revealed a clear transition from negative to positive photoconductivity as the Eu content x is increased at room temperature. This transition is related to the metal-insulator transition that occurs due to the disorder originated from the introduction of Eu atoms and it is an Anderson transition. Our investigation found that, from the potential application point of view, the sample x=0.06 is more suitable, i.e., it presents an almost noise-free signal and the higher photoconductivity amplitude response. The photoconductive amplitude response for the sample with x=0.06 was investigated further in the temperature range of 77-300 K and, surprisingly, multiple additional transitions were observed with amplitudes that reached around 200 times the original value before illumination. We show that this anomalous behavior is a consequence of the generation and recombination rates between the bands and the 4f level and a defect level located inside the band gap. [ABSTRACT FROM AUTHOR]