Hierarchical spatiotemporal modeling of human visceral leishmaniasis in Rio Grande do Norte, Brazil.

Visceral leishmaniasis (VL) is a neglected tropical disease that is globally distributed and has the potential to cause very serious illness. Prior literature highlights the emergence and spread of VL is influenced by multiple factors, such as socioeconomic status, sanitation levels or animal and human reservoirs. The study aimed to retrospectively investigate the presence and infectiousness of VL in Rio Grande do Norte (RN), Brazil between 2007 and 2020. We applied a hierarchical Bayesian approach to estimate municipality-specific relative risk of VL across space and time. The results show evidence that lower socioeconomic status is connected to higher municipality-specific VL risk. Overall, estimates reveal spatially heterogeneous VL risks in RN, with a high probability that VL risk for municipalities within the West Potiguar mesoregion are more than double the expected VL risk. Additionally, given the data available, results indicate there is a high probability of increasing VL risk in the municipalities of Natal, Patu and Pau dos Ferros. These findings demonstrate opportunities for municipality-specific public health policy interventions and warrant future research on identifying epidemiological drivers in at-risk regions.

Conventional cytologic diagnosis of human papillomavirus-induced anal intraepithelial neoplasia: The experience of a referral center in Rio de Janeiro, Brazil.

BACKGROUND: Screening of anal cancer is rarely available or performed in Brazil. This study analyzes the diagnostic performance of conventional cytology (CC) in the prevention of anal cancer in a coloproctology and gynecology outpatient clinics in a public hospital in Rio de Janeiro, Brazil. METHODS: From 2005 to 2017, 1066 conventional cytological samples were collected. We analyze the causes of unsatisfactory samples (11.3%) and compare the cytological diagnoses of 83 samples from persons living with HIV and persons not living with HIV and in specific situations, using as the gold standard high-resolution anoscopy or histopathology in cases biopsied within 6 months after cytology. RESULTS: The sensitivity of cytology with diagnosis of ASC-US for detection of anal intraepithelial neoplasia of any grade was 85%, specificity was 41%, positive and negative predictive values were 64% and 75%, respectively, and positive and negative likelihood ratios were 1.46 and 0.35, respectively. CONCLUSION: Conventional cytology available in resource-limited settings is a simple, noninvasive, low-cost method that proved feasible for outpatient screening of precursor lesions of the anal canal.

Preoperative Location Of Parathyroid Adenomas In Primary Hyperparathyroidism: The Role of Cervical Doppler Ultrasound.

INTRODUCTION: Parathyroid adenoma is the most frequent cause of primary hyperparathyroidism. In recent years, the preoperative location of parathyroid adenomas allowed minimally invasive surgical techniques that have become preferred over the traditional bilateral neck exploration. The more recent guidelines on this subject highlight the role of nuclear medicine imaging tests. The aim of this study was to review the current role of Doppler ultrasound (US) in assessing the preoperative location of parathyroid adenomas in patients with primary hyperparathyroidism. MATERIAL AND METHODS: Retrospective study based on data from patients with primary hyperparathyroidism that underwent parathyroidectomy between January 2013 and January 2022 at the Centro Hospitalar Universitário Lisboa Central. Statistical analysis was performed with IBM SPSS Statistics, version 26.0.0.0®. RESULTS: Parathyroidectomy was performed in 171 patients (77.8% females) with primary hyperparathyroidism. Cervical Doppler ultrasound was the most performed test (64.3%, n = 110) for preoperative location and detected a suspicious lesion in 98 patients (89.1%). The preoperative location of the parathyroid adenomas was assessed through the Doppler ultrasound and was compared with the surgical reports and histological findings; a correct identification was made in 76 patients (77.6%). Doppler ultrasound slightly underestimated the mean adenoma size (18.1 ± 7.7 mm preoperative versus 22 ± 8.4 mm postoperative). Calcium, parathyroid hormone levels, adenoma size and concomitant presence of thyroid nodules did not affect the accuracy of Doppler ultrasound. CONCLUSION: Doppler ultrasound showed high diagnostic accuracy even in patients with nodular thyroid disease regardless of calcium and parathyroid hormone levels and adenoma size. Furthermore, its safety, affordability and availability should favor its use as first line test in primary hyperparathyroidism to assess the preoperative location of parathyroid adenomas.

No Evidence of Rabies Exposure in Wild Marmosets (Callithrix jacchus) of Northeast Brazil.

Rabies transmitted by wildlife is the main source of human rabies mortality in Latin America and considered an emerging disease. The common marmoset Callithrix jacchus of Brazil is the only known primate reservoir of rabies worldwide. We tested whether alive free-ranging C. jacchus were exposed to rabies in four northeast states that have previously reported rabies-positive dead C. jacchus (Pernambuco and Bahia) or not (Paraíba and Rio Grande do Norte). Our results show no evidence of rabies antibodies or infection in the sampled C. jacchus, suggesting that apparently healthy marmosets are not widely exposed to rabies over their natural range.

Phenotypic Diversity of Seminal Root Traits in Bread Wheat Germplasm from Different Origins.

Bread wheat (Triticum aestivum L.) is a major staple crop, and more adapted varieties are needed to ensure productivity under unpredictable stress scenarios resulting from climate changes. In the development of new genotypes, root system traits are essential since roots have a key function in water and nutrient uptake, and root architecture determines the plant's ability to spatially explore the soil resources. Genetic variation in wheat root system may be assessed at the early stages of development. This study evaluates in vitro and at the seedling stage, the genetic diversity of root growth angle (RGA), seminal root number (SRN), and radicle length (RadL) in 30 bread wheat genotypes from different origins and belonging to distinct evolutive or breeding groups. SRN and RadL were analyzed at 1, 2, 3 and 6 days after sowing (DAS) and RGA was measured through the angle between the first pair of seminal roots. A large variability was found in RGA values that ranged from 63° to 122°. Although differences were found between genotypes within the same groups, the narrower angles tended to occur among landraces, while the higher RGA values were observed in advanced lines and Australian varieties. Differences were also observed as regards the SRN (1.0-3.0, 2.7-4.7, 3.2-5.0 and 4.4-6.3 at 1, 2, 3 and 6 DAS, respectively) and RadL (0.1-1.5, 2.1-5.0, 4.0-7.5 and 5.1-13.7 cm at 1, 2, 3 and 6 DAS, respectively). Genetic variability in root traits at seedling stage allows more rapid selection of genotypes better adapted to environmental and soil constraints, necessary to Portuguese Wheat Breeding Program. It will also contribute to the definition of wheat ideotypes with improved performance under Mediterranean climate conditions.

Grain Composition and Quality in Portuguese Triticum aestivum Germplasm Subjected to Heat Stress after Anthesis.

Bread wheat (Triticum aestivum) is a major crop worldwide, and it is highly susceptible to heat. In this work, grain production and composition were evaluated in Portuguese T. aestivum germplasm (landraces and commercial varieties), which was subjected to heat after anthesis (grain filling stage). Heat increased the test weight (TW) in Nabão, Grécia and Restauração, indicating an improved flour-yield potential. Mocho de Espiga Branca (MEB) and Transmontano (T94) showed higher thousand-kernel weight (TKW). Gentil Rosso presented increased soluble sugars, which are yeast substrates in the bread-making process. Ardila stood out for its protein increase under heat. Overall SDS was unaffected by higher temperature, but increased in T94, indicating a better dough elasticity for bread-making purposes. Under heat, lipid content was maintained in most genotypes, being endogenous fatty acids (FAs) key players in fresh bread quality. Lipid unsaturation, evaluated through the double bond index (DBI), also remained unaffected in most genotypes, suggesting a lower flour susceptibility to lipoperoxidation. In Grécia, heat promoted a higher abundance of monounsaturated oleic (C18:1) and polyunsaturated linoleic (C18:2) acids, which are essential fatty acids in the human diet. This work highlighted a great variability in most parameters both under control conditions or in response to heat during grain filling. Cluster analysis of traits revealed a lower susceptibility to heat during grain filling in Ardila, Restauração, and Ruivo, in contrast to MEQ, which seems to be more differentially affected at this stage. Characterization and identification of more favorable features under adverse environments may be relevant for agronomic, industrial, or breeding purposes, in view of a better crop adaptation to changing climate and an improved crop sustainability in agricultural systems more prone to heat stress.

Wheat Crop under Waterlogging: Potential Soil and Plant Effects.

Inundation, excessive precipitation, or inadequate field drainage can cause waterlogging of cultivated land. It is anticipated that climate change will increase the frequency, intensity, and unpredictability of flooding events. This stress affects 10-15 million hectares of wheat every year, resulting in 20-50% yield losses. Since this crop greatly sustains a population's food demands, providing ca. 20% of the world's energy and protein diets requirements, it is crucial to understand changes in soil and plant physiology under excess water conditions. Variations in redox potential, pH, nutrient availability, and electrical conductivity of waterlogged soil will be addressed, as well as their impacts in major plant responses, such as root system and plant development. Waterlogging effects at the leaf level will also be addressed, with a particular focus on gas exchanges, photosynthetic pigments, soluble sugars, membrane integrity, lipids, and oxidative stress.

Confiabilidade do EORTC QLQ-INFO25 para Avaliar a Necessidade de Informação de Pacientes Oncológicos / Reliability of the EORTC QLQ-INFO25 to Assess Cancer Patients' Information Needs / Fiabilidad de la EORTC QLQ-INFO25 para Evaluar las Necesidades de Información de los Pacientes con Cáncer

Introdução: A maioria dos pacientes não possui um grau satisfatório de compreensão acerca do câncer. Para que o processo de comunicação de informações seja verdadeiramente efetivo, é necessário identificar anteriormente o nível de conhecimento do paciente. Objetivo: Verificar a estabilidade teste-reteste do instrumento EORTC QLQ-INFO25 em sua versão em português do Brasil, para avaliação da necessidade de informação do paciente oncológico. Método: O instrumento foi aplicado em 253 pacientes hospitalizados nas enfermarias clínicas e cirúrgicas de um hospital de alta complexidade no tratamento do câncer situado no município do Rio de Janeiro, por meio de um questionário com entrevista individual. Para testar a adequação do processo de aferição, 85 pacientes aderiram ao reteste, com intervalo de sete a 15 dias. Os dados foram inseridos em um banco de dados por dupla digitação independente no programa Microsoft Excel. A análise foi realizada por meio da estatística Kappa simples e ponderada. Resultados: As respostas mostraram-se estáveis, e as estimativas de confiabilidade teste-reteste variaram de boas a excelentes (0,66 a 0,99). O instrumento também demonstrou boa estabilidade quando aplicado em outras populações e em pacientes com diferentes tipos de câncer. Conclusão: O instrumento EORTEC QLQ-INFO25 pode contribuir para a mensuração da satisfação do paciente em relação à sua necessidade de informação, uma vez que os resultados sugerem alta estabilidade das informações, tornando viável a sua aplicabilidade na população brasileira

Introduction: Most patients do not have a satisfactory degree of understanding about cancer. For the information communication process to be truly effective, it is necessary to identify the patient's level of knowledge beforehand. Objective: To verify the test-retest stability of the EORTC QLQ-INFO25 instrument, in its Brazilian Portuguese version, to assess cancer patient's information needs. Method: The instrument was applied in 253 patients hospitalized in the clinical and surgical wards of a highcomplexity cancer treatment hospital located in the city of Rio de Janeiro through the application of a questionnaire in an individual interview. To test the adequacy of the measurement process, 85 patients adhered to the retest, with an interval of 7 to 15 days. Data were entered into a database by independent double typing in the Excel program, and the analysis was performed using simple and weighted Kappa statistics. Results: Responses were stable, and test-retest reliability estimates ranged from good to excellent (0.66 to 0.99). The instrument also demonstrated good stability when applied to other populations and patients with different types of cancer. Conclusion: The EORTEC QLQ-INFO25 instrument can contribute for the measurement of patient satisfaction in relation to their need for information since the results suggest a high stability of information, making its applicability in the Brazilian population viable

Introducción: La mayoría de los pacientes no tiene un grado satisfactorio de conocimiento sobre el cáncer. Para que el proceso de comunicación de la información sea realmente efectivo, es necesario identificar de antemano el nivel de conocimiento del paciente. Objetivo: Verificar la estabilidad testretest del instrumento EORTC QLQ-INFO25, en su versión portuguesa de Brasil, para evaluar la necesidad de información en pacientes con cáncer. Método: El instrumento se aplicó a 253 pacientes hospitalizados en las salas clínico-quirúrgicas de un hospital de tratamiento oncológico de alta complejidad ubicado en la ciudad de Río de Janeiro mediante la aplicación de un cuestionario a modo de entrevista individual. Para probar la idoneidad del proceso de medición, 85 pacientes se adhirieron a la nueva prueba, con un intervalo de 7 a 15 días. Los datos se ingresaron en una base de datos mediante doble entrada independiente, en el programa Excel, y el análisis se realizó utilizando estadísticas Kappa simples y ponderada. Resultados: Las respuestas fueron estables y las estimaciones de fiabilidad test-retest variaron de buenas a excelentes (0,66 a 0,99). El instrumento también demostró una buena estabilidad cuando se aplicó a otras poblaciones y pacientes con diferentes tipos de cáncer. Conclusión: El instrumento EORTEC QLQINFO25 puede contribuir a la medición de la satisfacción del paciente en relación a su necesidad de información ya que los resultados sugieren una alta estabilidad de la información, viabilizando su aplicabilidad en la población brasileña

Iron in Hydroxyapatite: Interstitial or Substitution Sites?

Iron-doped hydroxyapatite (Fe-HAp) is regarded as a promising magnetic material with innate biocompatibility. Despite the many studies reported in the literature, a detailed theoretical description of Fe inclusions is still missing. There is even no consensual view on what kind of Fe defects take place in Fe-HAp-iron interstitial or calcium substitutions? In order to address these questions, we employ modern first-principles methodologies, including hybrid density functional theory, to find the geometry, electronic, magnetic and thermodynamic properties of iron impurities in Fe-HAp. We consider a total of 26 defect configurations, including substitutional (phosphorus and calcium sites) and interstitial defects. Formation energies are estimated considering the boundaries of chemical potentials in stable hydroxyapatite. We show that the most probable defect configurations are: Fe3+ and Fe2+ substitutions of Ca(I) and Ca(II) sites under Ca-poor conditions. Conversely, Fe interstitials near the edge of the hydroxyl channel are favored in Ca-rich material. Substitutional Fe on the P site is also a probable defect, and unlike the other forms of Fe, it adopts a low-spin state. The analysis of Fe K-XANES spectra available in the literature shows that Fe-HAp usually contains iron in different configurations.

Simulation and Computer Study of Structures and Physical Properties of Hydroxyapatite with Various Defects.

Simulation and computer studies of the structural and physical properties of hydroxyapatite (HAP) with different defects are presented in this review. HAP is a well-known material that is actively used in various fields of medicine, nanotechnology, and photocatalytic processes. However, all HAP samples have various defects and are still insufficiently studied. First of all, oxygen and OH group vacancies are important defects in HAP, which significantly affect its properties. The properties of HAP are also influenced by various substitutions of atoms in the HAP crystal lattice. The results of calculations by modern density functional theory methods of HAP structures with these different defects, primarily with oxygen and hydroxyl vacancies are analyzed in this review. The results obtained show that during the structural optimization of HAP with various defects, both the parameters of the crystallographic cells of the HAP change and the entire band structure of the HAP changes (changes in the band gap). This affects the electronic, optical, and elastic properties of HAP. The review considers the results of modeling and calculation of HAP containing various defects, the applied calculation methods, and the features of the effect of these defects on the properties of HAP, which is important for many practical applications.

Reasons for never receiving a pap test among Brazilian women: National health survey.

OBJECTIVE: To identify reasons among Brazilian women for never having a Pap test. DESIGN: We designed a cross-sectional study that used data from the National Health Survey. SAMPLE: Two thousand four hundred and two women 25-64 years old who never had a pap test. MEASURES: Variables were age, race, education, marital status, housing condition, primary health care access, health insurance, self-perceived health, and social support network. We calculated the prevalence of different reasons and odds ratios for each. RESULTS: The most frequent reason for never having a test were linked to women thinking the test was unnecessary (42.3%) which had a significant association with marital status (OR = 1.52; 95% CI = 1.07-1.91), age (OR = 1.56; 95% CI = 1.21-1.99), area of residence (OR = 1.15; 95% CI = 1.02-1.39), having a health insurance (OR = 1.18; 95% CI = 1.01-1.36), and self-perceived health (OR = 1.42; 95% CI = 1.28-1.56). The second most frequent reason was not knowing they needed a test (22.9%) which was associated with age (OR = 1.95; 95% CI = 1.74-2.16) and self-perceived health (OR = 1.56; 95% CI = 1.33-1.80). CONCLUSIONS: The findings suggest lack of knowledge about cervical cancer and its prevention among Brazilian women. We consider it essential that the health service can provide the test, as well as the necessary guidelines for raising the awareness of the target audience.

Assessing antiretroviral therapy success in HIV/AIDS morbidity and mortality trends in Brazil, 1990-2017: an interrupted time series study.

To describe the trends of HIV/AIDS metrics related to the burden of disease for Brazil between 1990 and 2017 we conducted a timeseries analysis for HIV/AIDS indicators by extracting data from the Global Burden of Disease study. We calculated traditional prevalence, incidence and mortality rates, the number of years lost by HIV-related deaths (YLL) and disability (YLD), and disability-adjusted life years (DALY). We estimated time series models and assessed the impact of highly active antiretroviral therapy (HAART) on the same indicators. In the set of disability-adjusted life years (DALY), the highest weight of its magnitude was due to YLL. There was a decline, especially after 1996, of DALY, mortality and YLL for HIV/AIDS. However, YLD, incidence, and prevalence increased over the same period. Also, the analysis of interrupted time series showed that the introduction of HAART into health policy had a significant impact on indicators, especially for DALY and YLL. We need to assess the quality of life of people living with HIV, especially among older adults. In addition, we need to focus on primary prevention, emphasizing methods to avoid infection and public policies should reflect this.

First-principles calculations of Stark shifts of electronic transitions for defects in semiconductors: the Si vacancy in 4H-SiC.

Point defects in solids are promising single-photon sources with application in quantum sensing, computing and communication. Herein, we describe a theoretical framework for studying electric field effects on defect-related electronic transitions, based on density functional theory calculations with periodic boundary conditions. Sawtooth-shaped electric fields are applied perpendicular to the surface of a two-dimensional defective slab, with induced charge singularities being placed in the vacuum layer. The silicon vacancy (V Si) in 4H-SiC is employed as a benchmark system, having three zero-phonon lines in the near-infrared (V1, V1' and V2) and exhibiting Stark tunability via fabrication of Schottky barrier or p-i-n diodes. In agreement with experimental observations, we find an approximately linear field response for the zero-phonon transitions of V Si involving the decay from the first excited state (named V1 and V2). However, the magnitude of the Stark shifts are overestimated by nearly a factor of 10 when comparing to experimental findings. We discuss several theoretical and experimental aspects which could affect the agreement.

Molecular modeling and computational study of the chiral-dependent structures and properties of the self-assembling diphenylalanine peptide nanotubes, containing water molecules.

DFT (VASP) and semi-empirical (HyperChem) calculations for the L- and D-chiral diphenylalanine (L-FF and D-FF) nanotube (PNT) structures, empty and filled with water/ice clusters, are presented and analyzed. The results obtained show that after optimization, the dipole moment and polarization of both chiral type L-FF and D-FF PNT and embedded water/ice cluster are enhanced; the water/ice cluster acquire the helix-like structure similar as L-FF and D-FF PNT. Ferroelectric properties of tubular water/ice helix-like-cluster obtained after optimization inside L-FF and D-FF PNT and total L-FF and D-FF PNT with embedded water/ice cluster are discussed.

Structures and Properties of the Self-Assembling Diphenylalanine Peptide Nanotubes Containing Water Molecules: Modeling and Data Analysis.

The structures and properties of the diphenylalanine (FF) peptide nanotubes (PNTs), both L-chiral and D-chiral (L-FF and D-FF) and empty and filled with water/ice clusters, are presented and analyzed. DFT (VASP) and semi-empirical calculations (HyperChem) to study these structural and physical properties of PNTs (including ferroelectric) were used. The results obtained show that after optimization the dipole moment and polarization of both chiral type L-FF and D-FF PNT and embedded water/ice cluster are enhanced; the water/ice cluster acquire the helix-like structure similar as L-FF and D-FF PNT. Ferroelectric properties of tubular water/ice helix-like cluster, obtained after optimization inside L-FF and D-FF PNT, as well of the total L-FF and D-FF PNT with embedded water/ice cluster, are discussed.

Parathyroid cyst: differential diagnosis.

Parathyroid cysts are rare lesions of the cervical region and less frequently of the mediastinum. They occur mostly in women and are usually asymptomatic. They generally occur in the fourth and fifth decades of life and mainly are non-functioning. They commonly present as a neck mass that is found incidentally during surgery or in imaging test. Its importance lies in the difficulty in diagnosis, often confusing itself with thyroid pathology. The diagnosis is usually made intraoperatively, confirmed by histopathological examination.The aim of this paper is to report a case of parathyroid cyst that mimics a thyroid nodule.

Characterisation of negative-U defects in semiconductors.

This review aims at providing a retrospective, as well as a description of the state-of-the-art and future prospects regarding the theoretical and experimental characterisation of negative-U defects in semiconductors. This is done by complementing the account with a description of the work that resulted in some of the most detailed, and yet more complex defect models in semiconductors. The essential physics underlying the negative-U behaviour is presented, including electronic correlation, electron-phonon coupling, disproportionation, defect transition levels and rates. Techniques for the analysis of the experimental data and modelling are also introduced, namely defect statistics, kinetics of carrier capture and emission, defect transformation, configuration coordinate diagrams and other tools. We finally include a showcase of several works that led to the identification of some of the most impacting negative-U defects in group-IV and compound semiconductors.

Comorbid infections induce progression of visceral leishmaniasis.

BACKGROUND: Visceral leishmaniasis (VL) is a vector borne zoonotic disease endemic in humans and dogs in Brazil. Due to the increased risk of human infection secondary to the presence of infected dogs, public health measures in Brazil mandate testing and culling of infected dogs. Despite this important relationship between human and canine infection, little is known about what makes the dog reservoir progress to clinical illness, significantly tied to infectiousness to sand flies. Dogs in endemic areas of Brazil are exposed to many tick-borne pathogens, which are likely to alter the immune environment and thus control of L. infantum. RESULTS: A cross-sectional study of 223 dogs from an area of Natal, in the Rio Grande do Norte, Brazil, were studied to determine the association between comorbid tick-borne disease and Leishmania infection in this endemic area. The risk of Leishmania seropositivity was 1.68× greater in dogs with tick-borne disease seropositivity compared to those without (Adjusted RR: 1.68, 95% CI: 1.09-2.61, P = 0.019). A longitudinal study of 214 hunting dogs in the USA was conducted to determine the causal relationship between infection with tick-borne diseases and progression of VL. Hunting dogs were evaluated three times across a full tick season to detect incident infection with tick-borne diseases. A logistic regression model with generalized estimating equations to estimate the parameters was used to determine how exposure to tick-borne disease altered VL progression over these three time points when controlling for other variables. Dogs infected with three or more tick-borne diseases were 11× more likely to be associated with progression to clinical VL than dogs with no tick-borne disease (Adjusted RR: 11.64, 95% CI: 1.22-110.99, P = 0.03). Dogs with exposure to both Leishmania spp. and tick-borne diseases were five times more likely to die during the study period (RR: 4.85, 95% CI: 1.65-14.24, P = 0.0051). CONCLUSIONS: Comorbid tick-borne diseases dramatically increased the likelihood that a dog had clinical L. infantum infection, making them more likely to transmit infection to sand flies and people. As an important consequence, reduction of tick-borne disease exposure through topical or oral insecticides may be an important way to reduce progression and transmissibility of Leishmania infection from the canine reservoir to people.

Atomic and electronic structure of the Si(331)-(12 × 1) surface.

We report on the investigation of the atomic and electronic structures of a clean Si(331)-(12 × 1) surface using a first-principles approach with both plane wave and strictly localized basis sets. Starting from the surface structure proposed by Zhachuk and Teys [Phys. Rev. B 95, 041412(R) (2017)], we develop significant improvements to the atomic model and localized basis set which are critical for the correct description of the observed bias dependence of scanning tunneling microscopy (STM) images. The size mismatch between the Si pentamers from the surface model and those seen by STM is explained within the context of the Tersoff-Hamann model. The energy barriers that separate different Si(331) buckled configurations were estimated, showing that the surface structure is prone to dynamic buckling at room temperature. It is found that empty electronic states on Si(331) are essentially localized on the pentamers with interstitials and under-coordinated Si sp 2-like atoms between them, while filled electronic states are localized on under-coordinated Si sp 3-like atoms and dimers on trenches. The calculated electronic density of states exhibits two broad peaks in the fundamental bandgap of Si: one near the valence band top and the other near the conduction band bottom. The resulting surface bandgap of 0.58 eV is in an excellent agreement with spectroscopy studies.