Secrecy Analysis of a Mu-MIMO LIS-Aided Communication Systems under Nakagami-m Fading Channels.

This study evaluates the performance of large intelligent surface (LIS) technology in the context of a multi-user MIMO mobile communication system (Mu-MIMO) proposed for the sixth generation (6G). LIS employs digitally controlled reflectors to enhance Signal-to-Interference plus Noise Ratio (SINR) and establish line of sight (LoS) connectivity in non-LoS environments, improving transmission security. Analytical expressions are derived to assess LIS performance metrics, including distribution parameters, bit error probability, and secrecy outage probability, considering the presence of eavesdroppers and environmental fading. The study highlights the potential of LIS technology to enhance the confidentiality and reliability of digital communication systems in next-generation networks.

Load Recognition in Home Energy Management Systems Based on Neighborhood Components Analysis and Regularized Extreme Learning Machine.

Efficient energy management in residential environments is a constant challenge, in which Home Energy Management Systems (HEMS) play an essential role in optimizing consumption. Load recognition allows the identification of active appliances, providing robustness to the HEMS. The precise identification of household appliances is an area not completely explored. Gaps like improving classification performance through techniques dedicated to separability between classes and models that achieve enhanced reliability remain open. This work improves several aspects of load recognition in HEMS applications. In this research, we adopt Neighborhood Component Analysis (NCA) to extract relevant characteristics from the data, seeking the separability between classes. We also employ the Regularized Extreme Learning Machine (RELM) to identify household appliances. This pioneering approach achieves performance improvements, presenting higher accuracy and weighted F1-Score values-97.24% and 97.14%, respectively-surpassing state-of-the-art methods and enhanced reliability according to the Kappa index, i.e., 0.9388, outperforming competing classifiers. Such evidence highlights the promising potential of Machine Learning (ML) techniques, specifically NCA and RELM, to contribute to load recognition and energy management in residential environments.

The Hyrax appliance with tooth anchorage variations in surgically assisted rapid maxillary expansion: a finite element analysis.

PURPOSE: It is known that a correct transverse maxillary dimension is a key factor for a stable occlusion, which brings functional and esthetic benefits for the patient. In patients presenting maxillary atresia and the completion of bone growth, a highly recommended option for correction is the surgically assisted rapid maxillary expansion (SARME) associated with the Hyrax appliance. The objective of this study was to evaluate the influence of tooth anchorage variations of the Hyrax appliance in SARME through finite element analysis, evaluating which anchorage option might be associated with more effective orthopedic results with less undesired side effects. METHODS: Five different dental anchoring conditions for the Hyrax appliance were simulated through FE analysis applying premolars and molars as anchorage, having the same force applied by the activation of the Hyrax screw (0.5 mm) in all groups. The maxillary displacement results (axes X, Y, and Z) and generated stresses for both teeth and maxillary bone were calculated and represented using a color scale. RESULTS: All groups presented significant bone displacement and stress concentration on anchoring teeth, with the group presenting anchorage in the 1st and 2nd molars showing the greatest maxillary horizontal displacement (axis X) and suggesting the lowest tendency of dental vestibular inclination. CONCLUSIONS: Variations in dental anchorage might substantially affect the maxillary bone and teeth displacement outcome. The protocol for the Hyrax apparatus in SARME applying the 1st and 2nd molars as anchorage might generate less tilting and inclination of the anchoring teeth.

Dimensional and morphologic characteristics of unilateral impacted maxillary central incisors.

INTRODUCTION: This cross-sectional study aimed to investigate the crown and root characteristics of impacted central incisors compared with spontaneously erupted contralateral incisors and the influence of etiologic and local factors on their dimensions. METHODS: Forty-five patients (22 boys, 23 girls) who underwent orthodontic treatment for unilateral impaction of maxillary central incisors were referred for cone-beam imaging. Dimensions of the impacted and contralateral incisors were assessed using Dolphin 3D software (Dolphin Imaging & Management Solutions, Chatsworth, Calif). Paired t test and linear regression were used to compare the characteristics of the impacted and contralateral teeth. RESULTS: Contralateral and impacted central incisors showed statistically significant differences for root length (95% confidence interval [CI], 2.32-3.46; P <0.001), mesiodistal crown-root angulation (95% CI, 4.09-15.95; P = 0.001), and labiolingual crown-root angulation (95% CI, -18.69 to -4.70; P = 0.002). Etiologic factors did not alter the dimensions of incisors (95% CI, -1.17 to 0.76; P = 0.672). According to the multiple linear regression the independent variables associated with root length of contralateral and impacted incisors were sex (ß = -0.904; 95% CI, -1.62 to - 0.19; P = 0.014) and the presence of impaction (ß = -2.87; 95% CI, -3.67 to -2.07; P <0.001). CONCLUSIONS: Regardless of their etiology, the impacted incisors showed roots that were 2.89 mm shorter than the contralateral incisors and had greater angulation in the mesiodistal and labiolingual directions. Girls showed a reduction of 0.904 mm (7.6%) on the lengths of roots of both impacted and contralateral central incisors. The presence of impaction led to a reduction of 25% in incisor root lengths. Approximately 30% of the impacted teeth showed crown-root angulations >20° resulting in an increased distal and labial angulation of the root apical portion.

Thermal comfort conditions at microclimate scale and surface urban heat island in a tropical city: A study on João Pessoa city, Brazil.

Surface urban heat islands (SUHIs) are one of the most studied phenomena in urban climates because they generate problems for the well-being of the urban population. This study analyzed the thermal comfort conditions at microclimate scale and SUHI for João Pessoa city, Brazil. Micrometeorological data (temperature and air humidity data) collected at 10 stations in 2011 and 2018 were used to calculate Thom's discomfort index (TDI) for João Pessoa city. Satellite images from Landsat 5/TM for 1991, 2006, and 2010 and Landsat 8/OLI for 2018 were used for land use and land cover classification and to identify SUHI. The obtained results highlighted that the SUHI area in João Pessoa city was 26 km2 and that almost half of the heat island area was concentrated in the Geisel, Aeroclube, Valentina, Distrito Industrial, Cristo Redentor, and Mangabeira neighborhoods. Regarding the micrometeorological data, higher values were obtained for 2018 in the dry periods (summer) and during the day. Based on the results, a considerable increase in discomfort during the daytime was observed in urbanized areas of the city from 2010 - 2018 due to the increase in the average temperature in João Pessoa between 1991 and 2018.

Disinfection of Orthodontic Elastomers and Its Effects on Tensile Strength.

OBJECTIVE: This study aimed to investigate the effect of different disinfection protocols on the mechanical properties of orthodontic elastomeric ligatures (EL), an important issue to biosafety improvement and infection control, and to avoid cross-contamination. METHODS: A total of 120 EL were randomly divided into 6 experimental groups (n = 20) according to the disinfection method employed: group 1, EL were not immersed in a disinfectant solution (control group); group 2, EL were immersed in 2% glutaraldehyde; group 3, EL were immersed in 70% alcohol solution; group 4, EL were cleaned in an ultrasound washing (UW) machine by immersion in 0.5% enzyme detergent solution; group 5, UW procedure was performed, followed by immersion in 2% glutaraldehyde; Group 6, UW procedure was performed, followed by immersion in 70% alcohol. After disinfection, EL were subjected to a tensile strength test where the maximum strength, maximum elongation, and work at failure were determined. Data were statistically evaluated using one-way ANOVA and Dunnett's t-test for multiple comparisons. RESULTS: Statistically significant different (P < .05) values were found between the disinfection methods, and 70% alcohol showed negative changes in all mechanical properties of orthodontic elastomers. By contrast, 2% glutaraldehyde did not show significant alteration in mechanical properties, whereas the UW procedure showed significant alteration in maximum strength and work at failure. CONCLUSION: Of the tested substances for disinfection, 2% glutaraldehyde was the only substance that did not cause significant changes in the mechanical properties of orthodontic elastics and is considered as an alternative for elastic disinfection before its use.

Evaluation of Electromyographic Activity of Masticatory Muscles in Adults with Posterior Crossbite.

Introduction: There is evidence that patients with posterior crossbite (PXB) have neuromuscular changes in the masticatory muscles. However, up to the present time, the relationship among these changes on the electromyographic activity of the masticatory muscles is still unclear. Objective: To systematic review the available literature on the electromyographic activity of masticatory muscles in adults with PXB. Methods: Between August 22 and September 9, 2020, we searched the following seven electronic databases: PubMed, EMBASE, Web of Science, Cochrane Library, SciELO, LILACS, and Scopus. No restrictions were applied regarding the language and year of publication. This systematic review was registered in the Prospective Register of Systematic Reviews (PROSPERO - CRD42020205057) database and conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. After data selection and extraction, the methodological quality of the selected studies was conducted independently by two reviewers, using two different evaluation tools. Results: 6957 records were initially located after the search process. In the end, eight papers were selected. Most studies were classified as having average to low methodological quality and moderate to high risk of bias. Based on the available evidence, adult patients with PXB have electromyographic activity changes in the masticatory muscles when compared with individuals without PXB. Moreover, adult patients with unilateral posterior crossbite (UPXB) have asymmetrical electromyographic activity when the crossbite side is compared with the noncrossbite side. Conclusion: Despite the lack of studies with high methodological quality, electromyographic evaluation of masticatory muscles should be considered in the diagnosis and in the orthodontic treatment plan of patients with PXB. Prospective studies with a higher sample size and follow-up time, conducted using a rigorous scientific methodology, are necessary to reach a more reliable conclusion.

Secrecy Analysis and Error Probability of LIS-Aided Communication Systems under Nakagami-m Fading.

Large intelligent surfaces (LIS) are a new trend to achieve higher spectral efficiency and signal-to-noise ratio in mobile communications. For this reason, this paper proposes metrics to analyze the performance of systems with multiple antennas aided by LIS and derive the spectral efficiency, secrecy outage probability, and bit error probability in an environment with Nakagami-m distributed fading. In addition to an eavesdropper, there is a single-antenna user, an array of antennas at the transmitter side and the possibility of a direct link between transmitter and receiver. This study assumes that the LIS performs non-ideal phase cancellation leading to a residual phase error that follows a Von Mises distribution, and shows that the resulting channel can be accurately approximated by a Gamma distributed SNR whose parameters are analytically derived. From these formulas, it is possible to evaluate the effect of the strength of the line-of-sight link by varying the Nakagami parameter, m.

Evaluation of Multivariable Modeling Methods for Monitoring the Health of Guyed Towers in Overhead Power Lines.

This article proposes a methodology for monitoring the structural stability of each tower of an electric power transmission line through sensor measurements which estimates the different situations that may indicate the need for intervention to prevent the structure collapsing. The extended Kalman filter was adopted to predict the failures, considering sensor fusion techniques such as the displacements of the upper central position of the tower above certain limits. The load of the stay cables is calculated from the natural frequencies, which are determined by the accelerometers connected to the cables. The average value of these forces, which must be higher than a normal limit, were calculated to predict a failure. All guyed towers of a power transmission line thousands of kilometers long will be individually monitored considering the methodology described in this study, which makes this article one of the first relevant research studies in this area. Typically, guyed towers must often be manually inspected to ensure that the stay cables have acceptable pretension to prevent a lack of stability in the transmission line towers.

An IoT-Based System for Monitoring the Health of Guyed Towers in Overhead Power Lines.

The collapse of overhead power line guyed towers is one of the leading causes of power grid failures, subjecting electricity companies to pay considerable, high-value fines. In this way, the current work proposes a novel and complete framework for the remote monitoring of mechanical stresses in guyed towers. The framework method comprises a mesh network for data forwarding and neural networks to improve the performance of Low-Power and Lossy Networks. The method also considers the use of multiple sensors in the sensor fusion technique. As a result, the risk of collapse of guyed cable towers reduces, due to the remote monitoring and preventive actions promoted by the framework. Furthermore, the proposed method uses multiple input variable fusions, such as accelerometers and tension sensors, to estimate the tower's displacement. These estimations help address the structural health of the tower against failures (i.e., loosening of the stay cables, displacement, and vibrations) that can cause catastrophic events, such as tower collapse or even cable rupture.

Sum-Rate Channel Capacity for Line-of-Sight Models.

This work considers a base station equipped with an M-antenna uniform linear array and L users under line-of-sight conditions. As a result, one can derive an exact series expansion necessary to calculate the mean sum-rate channel capacity. This scenario leads to a mathematical problem where the joint probability density function (JPDF) of the eigenvalues of a Vandermonde matrix WWH are necessary, where W is the channel matrix. However, differently from the channel Rayleigh distributed, this joint PDF is not known in the literature. To circumvent this problem, we employ Taylor's series expansion and present a result where the moments of mn are computed. To calculate this quantity, we resort to the integer partition theory and present an exact expression for mn. Furthermore, we also find an upper bound for the mean sum-rate capacity through Jensen's inequality. All the results were validated by Monte Carlo numerical simulation.

Long-term water quality conditions and trends in 12 tropical coastal rivers in Northeast Brazil.

The water quality and trends in 12 tropical rivers in northeastern Brazil over a 27-year period (1990-2016; N = 39,008 samples) were evaluated. The analyzed parameters included temperature, conductivity, pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), nitrogen (NH4+), total phosphorus (P), and fecal coliforms. Densely populated basins (> 1000 inhab km-2) presented lower DO values (average 3.4 mg l-1; 43% DO saturation), while those with low demographic density (< 100 inhab km-2) presented values that aligned well with the recommendations of environmental legislation (average 5.8 mg l-1; 75% DO saturation). The NH4+ and P compound concentrations were typical of water bodies affected by urban inputs. The average p values were above the allowable limit (< 0.1 mg l-1) at all stations. The NH4+ values were high at the stations showing low DO concentrations, which suggested that due to reducing conditions after NH4+ accumulation was favored in those aquatic systems. In densely populated basins, the average fecal coliform concentrations were > 40,000 MPN 100 ml-1, indicating the input of improperly treated domestic/industrial liquid wastes. For the period from 1990 to 2016, 45% of the stations (N = 19) showed a rate of DO reduction that ranged from 0.01 to 0.17 mg l-1.O2 year-1. An increase in NH4+ concentrations was observed in 33% of the stations (N = 14), with an estimated average increase rate from 0.013 to 1.8 mg l-1 NH4+ year-1. These results demonstrated that the rates of increase in anthropogenic factors were significant (p < 0.05), while the natural factors remained constant.

Evaluation of Machine Learning Methods for Monitoring the Health of Guyed Towers.

This paper presents the development of a methodology to detect and evaluate faults in cable-stayed towers, which are part of the infrastructure of Brazil's interconnected electrical system. The proposed method increases system reliability and minimizes the risk of service failure and tower collapse through the introduction of predictive maintenance methods based on artificial intelligence, which will ultimately benefit the end consumer. The proposed signal processing and interpretation methods are based on a machine learning approach, where the tower vibration is acquired from accelerometers that measure the dynamic response caused by the effects of the environment on the towers through wind and weather conditions. Data-based models were developed to obtain a representation of health degradation, which is primarily based on the finite element model of the tower, subjected to wind excitation. This representation is also based on measurements using a mockup tower with different types of provoked degradation that was subjected to ambient changes in the laboratory. The sensor signals are preprocessed and submitted to an autoencoder neural network to minimize the dimensionality of the resources involved, being analyzed by a classifier, based on a Softmax configuration. The results of the proposed configuration indicate the possibility of early failure detection and evolution evaluation, providing an effective failure detection and monitoring system.

Large Intelligent Surfaces Communicating Through Massive MIMO Rayleigh Fading Channels.

Large intelligent surfaces (LIS) promises not only to improve the signal to noise ratio, and spectral efficiency but also to reduce the energy consumption during the transmission. We consider a base station equipped with an antenna array using the maximum ratio transmission (MRT), and a large reflector array sending signals to a single user. Each subchannel is affected by the Rayleigh flat fading, and the reflecting elements perform non-perfect phase correction which introduces a Von Mises distributed phase error. Based on the central limit theorem (CLT), we conclude that the overall channel has an equivalent Gamma fading whose parameters are derived from the moments of the channel fading between the antenna array and LIS, and also from the LIS to the single user. Assuming that the equivalent channel can be modeled as a Gamma distribution, we propose very accurate closed-form expressions for the bit error probability and a very tight upper bound. For the case where the LIS is not able to perform perfect phase cancellation, that is, under phase errors, it is possible to analyze the system performance considering the analytical approximations and the simulated results obtained using the well known Monte Carlo method. The analytical expressions for the parameters of the Gamma distribution are very difficult to be obtained due to the complexity of the nonlinear transformations of random variables with non-zero mean and correlated terms. Even with perfect phase cancellation, all the fading coefficients are complex due to the link between the user and the base station that is not neglected in this paper.

Venom complexity of Bothrops atrox (common lancehead) siblings.

BACKGROUND: Variability in snake venoms is a well-studied phenomenon. However, sex-based variation of Bothrops atrox snake venom using siblings is poorly investigated. Bothrops atrox is responsible for the majority of snakebite accidents in the Brazilian Amazon region. Differences in the venom composition of Bothrops genus have been linked to several factors such as ontogeny, geographical distribution, prey preferences and sex. Thus, in the current study, venom samples of Bothrops atrox male and female siblings were analyzed in order to compare their biochemical and biological characteristics. METHODS: Venoms were collected from five females and four males born from a snake captured from the wild in São Bento (Maranhão, Brazil), and kept in the Laboratory of Herpetology of Butantan Intitute. The venoms were analyzed individually and as a pool of each gender. The assays consisted in protein quantification, 1-DE, mass spectrometry, proteolytic, phospholipase A2, L-amino acid oxidase activities, minimum coagulant dose upon plasma, minimum hemorrhagic dose and lethal dose 50%. RESULTS: Electrophoretic profiles of male's and female's venom pools were quite similar, with minor sex-based variation. Male venom showed higher LAAO, PLA2 and hemorrhagic activities, while female venom showed higher coagulant activity. On the other hand, the proteolytic activities did not show statistical differences between pools, although some individual variations were observed. Meanwhile, proteomic profile revealed 112 different protein compounds; of which 105 were common proteins of female's and male's venom pools and seven were unique to females. Despite individual variations, lethality of both pools showed similar values. CONCLUSION: Although differences between female and male venoms were observed, our results show that individual variations are significant even between siblings, highlighting that biological activities of venoms and its composition are influenced by other factors beyond gender.

Comparative proteomic profiling and functional characterization of venom pooled from captive Crotalus durissus terrificus specimens and the Brazilian crotalic reference venom.

The South American rattlesnake Crotalus durissus spp has a wide geographic distribution in Brazil. Although responsible for only a low proportion of ophidian accidents, it is considered one of the most medically important species of venomous snakes due to the high mortality rate (1.87%). Snake venom is a complex phenotype commonly subjected to individual intraspecific, ontogenetic and geographic variability. Compositional differences in pooled venom used in the immunization process may impact the efficacy of the antivenom. In order to assure standardized high-quality antivenom, the potency of each Brazilian crotalic antivenom batch is determined against the 'Brazilian Crotalic Reference Venom' (BCRV). BCRV is produced by Instituto Butantan using venom obtained from the first milking of recently wild-caught C. d. terrificus specimens brought to the Institute. The decrease in the number of snake donations experienced in recent years can become a threat to the production of future batches of BCRV. To evaluate the feasibility of using venom from long-term captive animals in the formulation of BCRV, we have compared the proteomic, biochemical and biological profiles of C. d. terrificus venom pooled from captive specimens (CVP- captive venom pool) and BCRV. Electrophoretic and venomics analyses revealed a very similar venom composition profile, but also certain differences in toxins abundance, with some low abundant protein families found only in BCRV. Enzymatic (L-amino acid oxidase, phospholipase A2 and proteolytic) and biological (myotoxic and coagulant) activities showed higher values in CVP than in BCRV. CVP also possessed slightly higher lethal effect, although the Instituto Butantan crotalic antivenom showed equivalent potency neutralizing BCRV and CVP. Our results strongly suggest that venom from long-term captive C. d. terrificus might be a valid alternative to generate an immunization mixture of equivalent quality to the currently in use reference venom.

Capacity Bounds for Dense Massive MIMO in a Line-of-Sight Propagation Environment.

The use of large-scale antenna arrays grants considerable benefits in energy and spectral efficiency to wireless systems due to spatial resolution and array gain techniques. By assuming a dominant line-of-sight environment in a massive multiple-input multiple-output scenario, we derive analytical expressions for the sum-capacity. Then, we show that convenient simplifications on the sum-capacity expressions are possible when working at low and high signal-to-noise ratio regimes. Furthermore, in the case of low and high signal-to-noise ratio regimes, it is demonstrated that the Gamma probability density function can approximate the probability density function of the instantaneous channel sum-capacity as the number of served devices and base station antennas grows, respectively. A second important demonstration presented in this work is that a Gamma probability density function can also be used to approximate the probability density function of the summation of the channel's singular values as the number of devices increases. Finally, it is important to highlight that the presented framework is useful for a massive number of Internet of Things devices as we show that the transmit power of each device can be made inversely proportional to the number of base station antennas.

Bit Error Rate Closed-Form Expressions for LoRa Systems under Nakagami and Rice Fading Channels.

We derive exact closed-form expressions for Long Range (LoRa) bit error probability and diversity order for channels subject to Nakagami-m, Rayleigh and Rician fading. Analytical expressions are compared with numerical results, showing the accuracy of our proposed exact expressions. In the limiting case of the Nakagami and Rice parameters, our bit error probability expressions specialize into the non-fading case.

Oral health-related quality of life in women with temporomandibular joint disk anterior displacement before and after disk repositioning and anchoring surgery assessed with the Oral Health Impact Profile (OHIP-14).

OBJECTIVES: The aim of this study was to assess and compare oral health-related quality of life (OHRQOL) in women with temporomandibular joint (TMJ) disk displacement without reduction, before disk repositioning and anchoring surgery, in short-term follow-up, in different age groups, and with use of the Oral Health Impact Profile (OHIP-14). STUDY DESIGN: Fifty women ages between 17 and 60 years were divided into 4 age groups: 17-27, 28-38, 39-49, and 50-60 years. All the patients were asked to answer the OHIP-14 form before surgery and during their short-term follow-up. Seven domains of OHRQOL were rated on a 5-point Likert scale from 0 (never) to 4 (very often). Domains' scores and total OHIP-14 were compared between times by using Student's t test in the whole sample and in the 4 age groups. RESULTS: Both the whole sample and the age groups (17-27, 28-38, 39-49 years) showed a statistically significant decrease in all scores (P < .01). The age group 50-60 years showed a decrease in scores significant only in functional limitation (P = .05) CONCLUSIONS: TMJ disk anterior displacement had a negative impact on women's OHRQOL because of physical pain, physical disability, and psychological discomfort. TMJ disk repositioning and anchoring surgery improved overall OHRQOL in patients between 17 and 49 years of age; however, in patients between 50 and 60 years of age, there was improvement only in physical pain.

The lesser anteater (Tamandua tetradactyla) is not tetradactyla, but pentadactyla.

The name of the species tetradactyla means "four digits." In the literature, the hand of the lesser anteater (Tamandua tetradactyla) is described as having four digits (I, II, III and IV) with the absence of a fifth digit. The purpose of this study was to carry out an update adequately proposing an anatomical description of the T. tetradactyla hand. The present findings were analysed on the validation of Morse's law for this species. In total, seven male cadavers were radiographed and dissected. We observed that the hand of the T. tetradactyla was formed by a carpus containing four bones in the proximal row, which in the medium lateral direction was the radial, intermediate, ulnar and accessory bones of the carpus, and the distal row was formed by carpal bones I, II, III and IV. There were five metacarpal bones (I, II, III, IV and V). The presence of five digits was verified but not confirmed with the literature. Digit I had two phalanges, the proximal and distal; digits II, III and IV had three phalanges: proximal, middle and distal. Digit five had only one phalanx, the proximal, but it was not externally visible. According to the findings of this study, the presence of the fifth digit raises the question of whether the term tetradactyla is the most appropriate to describe this species. This rudimentary fifth digit and the presence of a functional first digit show that the Morse's law does not applies for the T. tetradactyla species.