Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 51
Filtrar
Mais filtros

Bases de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Nat Chem Biol ; 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38302607

RESUMO

The leaf-cutter ant fungal garden ecosystem is a naturally evolved model system for efficient plant biomass degradation. Degradation processes mediated by the symbiotic fungus Leucoagaricus gongylophorus are difficult to characterize due to dynamic metabolisms and spatial complexity of the system. Herein, we performed microscale imaging across 12-µm-thick adjacent sections of Atta cephalotes fungal gardens and applied a metabolome-informed proteome imaging approach to map lignin degradation. This approach combines two spatial multiomics mass spectrometry modalities that enabled us to visualize colocalized metabolites and proteins across and through the fungal garden. Spatially profiled metabolites revealed an accumulation of lignin-related products, outlining morphologically unique lignin microhabitats. Metaproteomic analyses of these microhabitats revealed carbohydrate-degrading enzymes, indicating a prominent fungal role in lignocellulose decomposition. Integration of metabolome-informed proteome imaging data provides a comprehensive view of underlying biological pathways to inform our understanding of metabolic fungal pathways in plant matter degradation within the micrometer-scale environment.

2.
J Cell Mol Med ; 28(1): e18023, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-38146147

RESUMO

In recent years, an increasing number of observational studies have revealed an association between gut microbiota composition and psoriasis patients. However, whether this association reflects a causal relationship remains unclear. This study aimed to identify the causal relationship between gut microbiota and psoriasis through relevant research. In order to determine whether gut microbiota and psoriasis are causally related, we conducted a Mendelian randomization analysis using summary statistics from genome-wide association studies (GWAS). As the exposure factor, we used summary statistics data from a GWAS study conducted by the MiBioGen Consortium, including 18,340 individuals with whole-genome gut microbiota composition, and data from the FinnGen GWAS study on psoriasis, including 9267 patients and 364,071 controls as the disease outcome. Two-sample Mendelian randomization analysis was subsequently performed with inverse variance weighted, MR-Egger and weighted median, while sensitivity analyses were conducted to address heterogeneity and horizontal pleiotropy. The IVW results confirmed the causal relationship between certain gut microbiota groups and psoriasis. Specifically, family Veillonellaceae (OR = 1.162, 95% CI: 1.038-1.301, p = 0.009), genus Candidatus Soleaferrea (OR = 1.123, 95% CI: 1.011-1.247, p = 0.030) and genus Eubacterium fissicatena group (OR = 0.831, 95% CI: 0.755-0.915, p = 0.00016) showed significant associations. Sensitivity analysis did not reveal any abnormalities in SNPs. Currently, we have found some causal relationship between the gut microbiota and psoriasis. However, the study needs further RCTs for further validation.


Assuntos
Microbioma Gastrointestinal , Psoríase , Humanos , Estudo de Associação Genômica Ampla , Análise da Randomização Mendeliana , Polimorfismo de Nucleotídeo Único
3.
Anal Chem ; 95(33): 12313-12320, 2023 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-37565815

RESUMO

The detection of formic acid vapor in the usage environment is extremely important for human health and safety. The utilization of metal-organic frameworks (MOFs) for the detection of gaseous molecules is an attractive strategy. However, the rational design and construction of MOF-based gas sensors with high sensitivity and mechanical stability remain a significant challenge. In this study, a simple approach is reported to fabricate colorimetric aerogel sensors assembled from MOF particles via ice template-assisted methods. As the aerogel sensor with staggered lamellae structures significantly provides a high air-volume intake of flowing gas, it generates a sufficient probability of contact reactions for highly mobile target molecules. Additionally, it enhances the mechanical stability by providing stress resistance between the staggered lamellae structures. Compared to conventional film sensors for the detection of formic acid molecules, aerogel sensors exhibit an 8-fold lower limit of detection, 15-fold better sensitivity at low concentrations, 34-fold faster response time, and higher stability. This approach shows great potential for rapid and real-time detection of target molecules as well as superior performance in the structural construction of various gas-sensitive materials.

4.
J Proteome Res ; 21(8): 2023-2035, 2022 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-35793793

RESUMO

Metaproteomics has been increasingly utilized for high-throughput characterization of proteins in complex environments and has been demonstrated to provide insights into microbial composition and functional roles. However, significant challenges remain in metaproteomic data analysis, including creation of a sample-specific protein sequence database. A well-matched database is a requirement for successful metaproteomics analysis, and the accuracy and sensitivity of PSM identification algorithms suffer when the database is incomplete or contains extraneous sequences. When matched DNA sequencing data of the sample is unavailable or incomplete, creating the proteome database that accurately represents the organisms in the sample is a challenge. Here, we leverage a de novo peptide sequencing approach to identify the sample composition directly from metaproteomic data. First, we created a deep learning model, Kaiko, to predict the peptide sequences from mass spectrometry data and trained it on 5 million peptide-spectrum matches from 55 phylogenetically diverse bacteria. After training, Kaiko successfully identified organisms from soil isolates and synthetic communities directly from proteomics data. Finally, we created a pipeline for metaproteome database generation using Kaiko. We tested the pipeline on native soils collected in Kansas, showing that the de novo sequencing model can be employed as an alternative and complementary method to construct the sample-specific protein database instead of relying on (un)matched metagenomes. Our pipeline identified all highly abundant taxa from 16S rRNA sequencing of the soil samples and uncovered several additional species which were strongly represented only in proteomic data.


Assuntos
Microbiota , Proteômica , Microbiota/genética , Peptídeos/análise , Peptídeos/genética , Proteoma/genética , Proteômica/métodos , RNA Ribossômico 16S/genética , Solo
5.
Surg Endosc ; 34(6): 2780-2788, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32189117

RESUMO

BACKGROUND: In the management of mucosal neoplasm and early cancer, therapeutic gastrointestinal endoscopy evolved from simply polypectomy, endoscopic mucosal resection, endoscopic submucosal dissection (ESD), to endoscopic full thickness resection (EFTR). Full thickness clip closure followed by transmural resection mimics surgical principles. It is safe, effective, and technically less demanding compared to other techniques. Over-the-scope clip (OTSC)-assisted EFTR or OTSC-EFTR enables the endoscopists to manage difficult lesions. METHODS: We video recorded and report our 1-year single center experience of 12 consecutive EFTR cases since the dedicated OTSC-EFTR device was approved in the USA. RESULTS: We demonstrate that OTSC-EFTR can be very useful to manage residual neoplastic tissue that cannot be removed during conventional mucosal resection due to deeper invasion, submucosal fibrosis, scaring from prior intervention, and appendiceal involvement. Caution should be used for EFTR of the ileocecal valve lesions. CONCLUSION: We propose that layered or stacked biopsy of the appendiceal stump after EFTR should be performed to rule out a positive residual base. Due to the limited size of the FTRD resection hood (13 mm internal diameter × 23 mm depth), for larger sessile adenomas in the colon, we propose a hybrid approach for complete removal: piecemeal EMR for tumor debulking followed by OTSC-EFTR to achieve R0 resection. We believe OTSC-EFTR offers safety and efficiency with very high success rate.


Assuntos
Adenoma/cirurgia , Ressecção Endoscópica de Mucosa/métodos , Neoplasias Gastrointestinais/cirurgia , Instrumentos Cirúrgicos , Técnicas de Fechamento de Ferimentos/instrumentação , Idoso , Colo/patologia , Colo/cirurgia , Ressecção Endoscópica de Mucosa/instrumentação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasia Residual/cirurgia , Estudos Retrospectivos , Resultado do Tratamento
6.
Appl Microbiol Biotechnol ; 103(10): 4229-4240, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30923872

RESUMO

Extremely acidic soils of natural forests in Nanling National Nature Reserve have been previously investigated and revisited in two successive years to reveal the active ammonia oxidizers. Ammonia-oxidizing archaea (AOA) rather than ammonia-oxidizing bacteria (AOB) were found more functionally important in the extremely acidic soils of the natural forests in Nanling National Nature Reserve. The relative abundances of Nitrosotalea, Nitrososphaera sister group, and Nitrososphaera lineages recovered by ammonia monooxygenase subunit A (amoA) transcripts were reassessed and compared to AOA communities formerly detected by genomic DNA. Nitrosotalea, previously found the most abundant AOA, were the second-most-active lineage after Nitrososphaera sister group. Our field study results, therefore, propose the acidophilic AOA, Nitrosotalea, can better reside in extremely acidic soils while they may not contribute to nitrification proportionately according to their abundances or they are less functionally active. In contrast, the functional importance of Nitrososphaera sister group may be previously underestimated and the functional dominance further extends their ecological distribution as little has been reported. Nitrososphaera gargensis-like AOA, the third abundant lineage, were more active in summer. The analyses of AOA community composition and its correlation with environmental parameters support the previous observations of the potential impact of organic matter on AOA composition. Al3+, however, did not show a strong adverse correlation with the abundances of functional AOA unlike in the DNA-based study. The new data further emphasize the functional dominance of AOA in extremely acidic soils, and unveil the relative contributions of AOA lineages to nitrification and their community transitions under the environmental influences.


Assuntos
Amônia/metabolismo , Archaea/classificação , Archaea/metabolismo , Florestas , Microbiota , Microbiologia do Solo , Archaea/enzimologia , Archaea/genética , Concentração de Íons de Hidrogênio , Oxirredução , Oxirredutases/análise , Oxirredutases/genética , RNA Mensageiro/análise , RNA Mensageiro/genética , Solo/química
7.
Appl Microbiol Biotechnol ; 103(2): 995-1005, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30474727

RESUMO

Biological nitrogen fixation (BNF) is an important natural biochemical process converting the inert dinitrogen gas (N2) in the atmosphere to ammonia (NH3) in the N cycle. In this study, the nifH gene was chosen to detect the diazotrophic microorganisms with high-throughput sequencing from five acidic forest soils, including three natural forests and two re-vegetated forests. Soil samples were taken in two seasons (summer and winter) at two depth layers (surface and lower depths). A dataset of 179,600 reads obtained from 20 samples were analyzed to provide the microbial community structure, diversity, abundance, and relationship with physiochemical parameters. Both archaea and bacteria were detected in these samples and diazotrophic bacteria were the dominant members contributing to the biological dinitrogen fixation in the acidic forest soils. Cyanobacteria, Firmicutes, Proteobacteria, Spirocheates, and Verrucomicrobia were observed, especially the Proteobacteria as the most abundant phylum. The core genera were Bradyrhizobium and Methylobacterium from α-Proteobacteia, and Desulfovibrio from δ-Proteobacteia in the phylum of Proteobacteia of these samples. The diversity indices and the gene abundances of all samples were higher in the surface layer than the lower layer. Diversity was apparently higher in re-vegetated forests than the natural forests. Significant positive correlation to the organic matter and nitrogen-related parameters was observed, but there was no significant seasonal variation on the community structure and diversity in these samples between the summer and winter. The application of high-throughput sequencing method provides a better understanding and more comprehensive information of diazotrophs in acidic forest soils than conventional and PCR-based ones.


Assuntos
Archaea/classificação , Bactérias/classificação , Variação Genética , Microbiota , Fixação de Nitrogênio , Oxirredutases/genética , Microbiologia do Solo , Ácidos/análise , Archaea/enzimologia , Archaea/genética , Archaea/metabolismo , Bactérias/enzimologia , Bactérias/genética , Bactérias/metabolismo , Fenômenos Químicos , Florestas , Sequenciamento de Nucleotídeos em Larga Escala , Metagenômica , Estações do Ano , Solo/química
8.
Appl Microbiol Biotechnol ; 102(12): 5309-5322, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29687145

RESUMO

Forest ecosystems have great ecological values in mitigation of climate change and protection of biodiversity of flora and fauna; re-forestry is commonly used to enhance the sequestration of atmospheric CO2 into forest storage biomass. Therefore, seasonal and spatial dynamics of the major microbial players in nitrification, ammonia-oxidizing archaea (AOA) and bacteria (AOB), in acidic soils of young and matured revegetated forests were investigated to elucidate the changes of microbial communities during forest restoration, and compared to delineate the patterns of community shifts under the influences of environmental factors. AOA were more abundant than AOB in both young and matured revegetated forest soils in both summer and winter seasons. In summer, however, the abundance of amoA-AOA decreased remarkably (p < 0.01), ranging from 1.90 (± 0.07) × 108 copies per gram dry soil in matured forest to 5.04 (± 0.43) × 108 copies per gram dry soil in young forest, and amoA-AOB was below detection limits to obtain any meaningful values. Moreover, exchangeable Al3+ and organic matter were found to regulate the physiologically functional nitrifiers, especially AOA abundance in acidic forest soils. AOB community in winter showed stronger correlation with the restoration status of revegetated forests and AOA community dominated by Nitrosotalea devanaterra, in contrast, was more sensitive to the seasonal and spatial variations of environmental factors. These results enrich the current knowledge of nitrification during re-forestry and provide valuable information to developmental status of revegetated forests for management through microbial analysis.


Assuntos
Amônia/metabolismo , Archaea/fisiologia , Fenômenos Fisiológicos Bacterianos , Biodiversidade , Recuperação e Remediação Ambiental , Florestas , Microbiologia do Solo , Archaea/classificação , Bactérias/classificação , Nitrificação , Oxirredução , Densidade Demográfica , Estações do Ano , Solo/química
9.
Sensors (Basel) ; 18(9)2018 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-30200366

RESUMO

As a specific force sensor, the tri-axis accelerometer is one of the core instruments in an inertial navigation system (INS). During navigation, its measurement error directly induces constant or alternating navigation errors of the same order of magnitude. Moreover, it also affects the estimation accuracy of gyro drift coefficients during the initial alignment and calibration, which will indirectly result in navigation errors accumulating over time. Calibration can effectively improve measurement accuracy of the accelerometer. Device-level calibration can identify all of the parameters in the error model, and the system-level calibration can accurately estimate part of these parameters. Combining the advantages of both the methods and making full use of the precise angulation of the space-stabilized platform, this paper proposes a three-stage accelerometer self-calibration technique that can be implemented directly in the space-stable INS. The device-level calibration is divided into two steps considering the large amount of parameters. The first step is coarse calibration, which identifies parameters except for the nonlinear terms, and the second step is fine calibration, which not only identifies the nonlinear parameters, but also improves the accuracy of the parameters identified in the first step. The follow-on system-level calibration is carried out on part of the parameters using specific force error and attitude error to further improve the calibration accuracy. Simulation result shows that by using the proposed three-stage calibration technique in the space-stable INS, the estimation accuracy of accelerometer error can reach 1 × 10 - 6   g order of magnitude. Experiment results show that after the three-stage calibration, the accuracy of latitude, longitude, and attitude angles has increased by over 45% and the accuracy of velocity has increased by over 22% during navigation.

10.
Sensors (Basel) ; 18(5)2018 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-29757242

RESUMO

Transverse navigation has been proposed to help inertial navigation systems (INSs) fill the gap of polar navigation ability. However, as the transverse system does not have the ability of navigate globally, a complicated switch between the transverse and the traditional algorithms is necessary when the system moves across the polar circles. To maintain the inner continuity and consistency of the core algorithm, a hybrid transverse polar navigation is proposed in this research based on a combination of Earth-fixed-frame mechanization and transverse-frame outputs. Furthermore, a thorough analysis of kinematic error characteristics, proper damping technology and corresponding long-term contributions of main error sources is conducted for the high-precision INSs. According to the analytical expressions of the long-term navigation errors in polar areas, the 24-h period symmetrical oscillation with a slowly divergent amplitude dominates the transverse horizontal position errors, and the first-order drift dominates the transverse azimuth error, which results from the gyro drift coefficients that occur in corresponding directions. Simulations are conducted to validate the theoretical analysis and the deduced analytical expressions. The results show that the proposed hybrid transverse navigation can ensure the same accuracy and oscillation characteristics in polar areas as the traditional algorithm in low and mid latitude regions.

11.
Microb Ecol ; 74(4): 910-922, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28808742

RESUMO

Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are the main nitrifiers which are well studied in natural environments, and AOA frequently outnumber AOB by orders especially in acidic conditions, making AOA the most promising ammonia oxidizers. The phylogeny of AOA revealed in related studies, however, often varied and hardly reach a consensus on functional phylotypes. The objective of this study was to compare ammonia-oxidizing communities by amoA gene and transcript based on both genomic DNA and RNA in extremely acidic forest soils (pH <4.5). Our results support the numerical and functional dominance of AOA over AOB in acidic soils as bacterial amoA gene and transcript were both under detection limits and archaeal amoA, in contrast, were abundant and responded to the fluctuations of environmental factors. Organic matter from tree residues was proposed as the main source of microbial available nitrogen, and the potential co-precipitation of dissolved organic matter (DOM) with soluble Al3+ species in acidic soil matrix may further restrict the amount of nitrogen sources required by AOB besides NH3/NH4+ equilibrium. Although AOA were better adapted to oligotrophic environments, they were susceptible to the toxicity of exchangeable Al3+. Phylotypes affiliated to Nitrososphaera, Nitrososphaera sister group, and Nitrosotalea were detected by amoA gene and transcript. Nitrosotalea devantaerra and Nitrososphaera sister group were the major AOA. Compared to the genomic DNA data, higher relative abundances of Nitrososphaera and Nitrososphaera sister group were recognized in amoA transcript inferred AOA communities, where Nitrosotalea relative abundance was found lower, implying the functional activities of Nitrososphaera sister group and Nitrososphaera were easily underestimated and Nitrosotalea did not attribute proportionally to nitrification in extremely acidic soils. Further comparison of the different AOA community compositions and relative abundance of each phylotypes revealed by amoA genes and transcripts make it possible to identify the functional AOA species and assess their ecological role in extremely acidic soils.


Assuntos
Archaea/fisiologia , Proteínas Arqueais/análise , Agricultura Florestal , Microbiota , Microbiologia do Solo , Amônia/metabolismo , Archaea/classificação , China , Cunninghamia/crescimento & desenvolvimento , Florestas , Oxirredução , Filogenia
12.
J Environ Manage ; 198(Pt 2): 41-49, 2017 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-28500915

RESUMO

Denitrification plays a key role in converting reactive nitrogen species to dinitrogen gas back into the atmosphere to maintain the equilibrium of nitrogen cycling in ecosystems. In this study, functional genes of nirK and nosZ were used to detect the community structure and abundance of denitrifying microorganisms in acidic forest soils in southern China. Three sets of factors were considered for a comparison among 5 forests, including forest types (natural vs. re-vegetated), depths (surface layer vs. lower layer) and seasons (winter vs. summer). The community of nirK gene detected from these acidic forest soils was closely related to Proteobacteria especially α-Proteobacteria and uncultured soil sequences, while that of nosZ gene was affiliated with the α-, ß- and γ-Proteobacteria. Higher diversity of denitrifiers was observed in re-vegetated forest soils than natural ones. Not only the community but also the abundance showed significant differences between forest types as well as depths. The abundance of denitrifiers ranged from 105 to 107 gene copies g-1 dry soil in this study. For nirK gene, the abundance was much higher in the lower layer than surface layer in both forest types, and the differences between winter and summer in natural forest soils were higher than those in re-vegetated forest soils. The abundance of nosZ and nirK genes showed a similar trend in natural forest, but the former was higher in matured forest than re-vegetated forest. This study provided a direct comparison on community composition and abundance of denitrifying bacteria in natural and re-vegetated acidic forest soils to allow further assessment of the nitrogen cycling.


Assuntos
Desnitrificação , Florestas , Microbiologia do Solo , Bactérias , China , Solo
13.
Gastrointest Endosc ; 84(3): 424-433.e2, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26873530

RESUMO

BACKGROUND AND AIMS: EUS-guided FNA or biopsy sampling is widely practiced. Optimal sonographic visualization of the needle is critical for image-guided interventions. Of the several commercially available needles, bench-top testing and direct comparison of these needles have not been done to reveal their inherent echogenicity. The aims are to provide bench-top data that can be used to guide clinical applications and to promote future device research and development. METHODS: Descriptive bench-top testing and comparison of 8 commonly used EUS-FNA needles (all size 22 gauge): SonoTip Pro Control (Medi-Globe); Expect Slimline (Boston Scientific); EchoTip, EchoTip Ultra, EchoTip ProCore High Definition (Cook Medical); ClearView (Conmed); EZ Shot 2 (Olympus); and BNX (Beacon Endoscopic), and 2 new prototype needles, SonoCoat (Medi-Globe), coated by echogenic polymers made by Encapson. Blinded evaluation of standardized and unedited videos by 43 EUS endoscopists and 17 radiologists specialized in GI US examination who were unfamiliar with EUS needle devices. RESULTS: There was no significant difference in the ratings and rankings of these needles between endosonographers and radiologists. Overall, 1 prototype needle was rated as the best, ranking 10% to 40% higher than all other needles (P < .01). Among the commercially available needles, the EchoTip Ultra needle and the ClearView needle were top choices. The EZ Shot 2 needle was ranked statistically lower than other needles (30%-75% worse, P < .001). CONCLUSIONS: All FNA needles have their inherent and different echogenicities, and these differences are similarly recognized by EUS endoscopists and radiologists. Needles with polymeric coating from the entire shaft to the needle tip may offer better echogenicity.


Assuntos
Aspiração por Agulha Fina Guiada por Ultrassom Endoscópico/instrumentação , Agulhas , Gastroenterologistas , Humanos , Imagens de Fantasmas , Radiologistas , Gravação de Videoteipe
14.
Appl Microbiol Biotechnol ; 100(17): 7727-39, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27178181

RESUMO

Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two new processes of recent discoveries linking the microbial nitrogen and carbon cycles. In this study, 16S ribosomal RNA (rRNA) gene of anammox bacteria and pmoA gene of n-damo bacteria were used to investigate their distribution and diversity in natural acidic and re-vegetated forest soils. The 16S rRNA gene sequences retrieved featured at least three species in two genera known anammox bacteria, namely Candidatus Brocadia anammoxidans, Candidatus Brocadia fulgida, and Candidatus Kuenenia stuttgartiensis while the pmoA gene amplified was affiliated with two species of known n-damo bacteria Candidatus Methylomirabilis oxyfera and a newly established Candidatus Methylomirabilis sp. According to the results, the diversity of anammox bacteria in natural forests was lower than in re-vegetated forests, but no significant difference was observed in n-damo community between them. Quantitative real-time PCR showed that both anammox and n-damo bacteria were more abundant in the lower layer (10-20 cm) than the surface layer (0-5 cm). The abundance of anammox bacteria varied from 2.21 × 10(5) to 3.90 × 10(6) gene copies per gram dry soil, and n-damo bacteria quantities were between 1.69 × 10(5) and 5.07 × 10(6) gene copies per gram dry soil in the two different layers. Both anammox and n-damo bacteria are reported for the first time to co-occur in acidic forest soil in this study, providing a more comprehensive information on more defined microbial processes contributing to C and N cycles in the ecosystems.


Assuntos
Compostos de Amônio/metabolismo , Bactérias/metabolismo , Metano/metabolismo , Nitritos/metabolismo , Bactérias/classificação , Bactérias/genética , Florestas , Oxirredução , RNA Ribossômico 16S/genética , Microbiologia do Solo
15.
Sensors (Basel) ; 16(12)2016 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-27999351

RESUMO

The gravity disturbance vector is one of the major error sources in high-precision and long-term inertial navigation applications. Specific to the inertial navigation systems (INSs) with high-order horizontal damping networks, analyses of the error propagation show that the gravity-induced errors exist almost exclusively in the horizontal channels and are mostly caused by deflections of the vertical (DOV). Low-frequency components of the DOV propagate into the latitude and longitude errors at a ratio of 1:1 and time-varying fluctuations in the DOV excite Schuler oscillation. This paper presents two gravity compensation methods using the Earth Gravitational Model 2008 (EGM2008), namely, interpolation from the off-line database and computing gravity vectors directly using the spherical harmonic model. Particular attention is given to the error contribution of the gravity update interval and computing time delay. It is recommended for the marine navigation that a gravity vector should be calculated within 1 s and updated every 100 s at most. To meet this demand, the time duration of calculating the current gravity vector using EGM2008 has been reduced to less than 1 s by optimizing the calculation procedure. A few off-line experiments were conducted using the data of a shipborne INS collected during an actual sea test. With the aid of EGM2008, most of the low-frequency components of the position errors caused by the gravity disturbance vector have been removed and the Schuler oscillation has been attenuated effectively. In the rugged terrain, the horizontal position error could be reduced at best 48.85% of its regional maximum. The experimental results match with the theoretical analysis and indicate that EGM2008 is suitable for gravity compensation of the high-precision and long-term INSs.

16.
Clin Gastroenterol Hepatol ; 12(2): 246-52.e1, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23920033

RESUMO

BACKGROUND & AIMS: Gastric ischemia is infrequently reported in the medical literature and under-recognized clinically and histopathologically. Various medical terms are used to describe gastric ischemia. We define and review the pathogenesis, diagnosis, and management of gastric ischemia. METHODS: We describe 6 cases of gastric ischemia. We discuss features of the gastric vascular supply and review literature on this disorder. RESULTS: Gastric ischemia results from diffuse or localized vascular insufficiency caused by etiologies such as systemic hypotension, vasculitis, or disseminated thromboembolism. The disorder is managed by fluid resuscitation, nasogastric tube placement (for intermittent air and fluid aspiration, to prevent or reduce gastric distention), aggressive acid reduction (via intravenous administration of proton pump inhibitors), and selective use of broad-spectrum antibiotics for patients with sepsis or gastric pneumatosis. CONCLUSIONS: Gastric ischemia has a poor prognosis. Early diagnosis is required for appropriate patient management.


Assuntos
Isquemia/patologia , Estômago/irrigação sanguínea , Adulto , Idoso de 80 Anos ou mais , Artéria Celíaca/anatomia & histologia , Endoscopia Gastrointestinal , Feminino , Mucosa Gástrica/patologia , Humanos , Isquemia/diagnóstico , Isquemia/etiologia , Isquemia/terapia , Pessoa de Meia-Idade , Prognóstico , Estômago/patologia , Volvo Gástrico/complicações
17.
Am J Gastroenterol ; 109(2): 155-9, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24496418

RESUMO

OBJECTIVES: Traditional personal interviews are subject to limitations imposed by geographic, financial, and scheduling constraints. Web-based videoconferencing (WVC) has the potential to simplify the interview process. This study was intended to evaluate the feasibility and utility of WVC using standard tablets/computers with videoconferencing capability in gastroenterology (GI) fellowship interviews. METHODS: At a single institution, 16 GI fellowship applicants participated in WVC with one interviewer, who was present at a remote location 750 miles away. In addition, each of the candidates underwent traditional interviews with four faculty members at the program site. All study interviewees used an iPad2 (Apple, iOS 5.1; Apple) with a videoconferencing application (Facetime). The interviewer (SRD) used Facetime on a MacBook Pro (Apple, Mac OS X 10.7.3). Each candidate completed a voluntary paper survey after completion of all assigned faculty interviews. RESULTS: The average age of the candidates was 30 years (range, 27-37 years). Fourteen candidates were native English speakers. Candidates expressed a high level of satisfaction, with 13 candidates (81%) stating that their WVC experience met or exceeded their expectations, and 87% of candidates stating that WVC should be an option in fellowship interviews. In addition, 25% of candidates felt that their WVC experience was equivalent to or better than their traditional interview experience on the same day. CONCLUSIONS: WVC can be an effective and useful tool in the fellowship interview process. It affords candidates increased flexibility, cost saving, convenience, and provides an option for participating in the selection process at more programs. For the programs and faculty, WVC has a potential to be an effective screening tool, can help minimize loss of clinical revenue and can also be an acceptable alternative to in-person interviews.


Assuntos
Bolsas de Estudo/organização & administração , Gastroenterologia/educação , Internet , Entrevistas como Assunto/métodos , Seleção de Pessoal/métodos , Comunicação por Videoconferência/estatística & dados numéricos , Adulto , Redução de Custos , Estudos de Viabilidade , Feminino , Humanos , Internato e Residência/organização & administração , Masculino , Satisfação Pessoal , Seleção de Pessoal/economia , Estados Unidos , Comunicação por Videoconferência/economia , Recursos Humanos
18.
Surg Innov ; 21(5): 513-9, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24172165

RESUMO

BACKGROUND: Modern endoscopy requires video display. Recent miniaturized, ultraportable projectors are affordable, durable, and offer quality image display. OBJECTIVE: Explore feasibility of using ultraportable projectors in endoscopy. METHODS: Prospective bench-top comparison; clinical feasibility study. Masked comparison study of images displayed via 2 Samsung ultraportable light-emitting diode projectors (pocket-sized SP-HO3; pico projector SP-P410M) and 1 Microvision Showwx-II Laser pico projector. BENCH-TOP FEASIBILITY STUDY: Prerecorded endoscopic video was streamed via computer. CLINICAL COMPARISON STUDY: Live high-definition endoscopy video was simultaneously displayed through each processor onto a standard liquid crystal display monitor and projected onto a portable, pull-down projection screen. Endoscopists, endoscopy nurses, and technicians rated video images; ratings were analyzed by linear mixed-effects regression models with random intercepts. RESULTS: All projectors were easy to set up, adjust, focus, and operate, with no real-time lapse for any. Bench-top study outcomes: Samsung pico preferred to Laser pico, overall rating 1.5 units higher (95% confidence interval [CI] = 0.7-2.4), P < .001; Samsung pocket preferred to Laser pico, 3.3 units higher (95% CI = 2.4-4.1), P < .001; Samsung pocket preferred to Samsung pico, 1.7 units higher (95% CI = 0.9-2.5), P < .001. The clinical comparison study confirmed the Samsung pocket projector as best, with a higher overall rating of 2.3 units (95% CI = 1.6-3.0), P < .001, than Samsung pico. CONCLUSIONS: Low brightness currently limits pico projector use in clinical endoscopy. The pocket projector, with higher brightness levels (170 lumens), is clinically useful. Continued improvements to ultraportable projectors will supply a needed niche in endoscopy through portability, reduced cost, and equal or better image quality.


Assuntos
Endoscopia/instrumentação , Cirurgia Vídeoassistida/instrumentação , Endoscopia/métodos , Ergonomia/instrumentação , Estudos de Viabilidade , Humanos , Estudos Prospectivos , Cirurgia Vídeoassistida/métodos
19.
Guang Pu Xue Yu Guang Pu Fen Xi ; 34(7): 1973-7, 2014 Jul.
Artigo em Zh | MEDLINE | ID: mdl-25269319

RESUMO

Extraction method for dynamic spectrum (DS) with a high signal to noise ratio is a key to achieving high-precision noninvasive detection of blood components. In order to further improve the accuracy and speed of DS extraction, linear similarity between photoelectric plethysmographys (PPG) at each two different wavelengths was analyzed in principle, and an experimental verification was conducted. Based on this property, the method of compensation-fitting extraction was proposed. Firstly, the baseline of PPG at each wavelength is estimated and compensated using single-period sampling average, which would remove the effect of baseline drift caused by motion artifact. Secondly, the slope of least squares fitting between each single-wavelength PPG and full-wavelength averaged PPG is acquired to construct DS, which would significantly suppress random noise. Contrast experiments were conducted on 25 samples in NIR wave band and Vis wave band respectively. Flatness and processing time of DS using compensation-fitting extraction were compared with that using single-trial estimation. In NIR band, the average variance using compensation-fitting estimation was 69.0% of that using single-trial estimation, and in Vis band it was 57.4%, which shows that the flatness of DS is steadily improved. In NIR band, the data processing time using compensation-fitting extraction could be reduced to 10% of that using single-trial estimation, and in Vis band it was 20%, which shows that the time for data processing is significantly reduced. Experimental results show that, compared with single-trial estimation method, dynamic spectrum compensation-fitting extraction could steadily improve the signal to noise ratio of DS, significantly improve estimation quality, reduce data processing time, and simplify procedure. Therefore, this new method is expected to promote the development of noninvasive blood components measurement.


Assuntos
Análise Química do Sangue/métodos , Espectroscopia de Luz Próxima ao Infravermelho , Análise dos Mínimos Quadrados , Pletismografia , Razão Sinal-Ruído
20.
mSystems ; : e0009924, 2024 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-38980057

RESUMO

Recent studies have revealed diverse RNA viral communities in soils. Yet, how environmental factors influence soil RNA viruses remains largely unknown. Here, we recovered RNA viral communities from bulk metatranscriptomes sequenced from grassland soils managed for 5 years under multiple environmental conditions including water content, plant presence, cultivar type, and soil depth. More than half of the unique RNA viral contigs (64.6%) were assigned with putative hosts. About 74.7% of these classified RNA viral contigs are known as eukaryotic RNA viruses suggesting eukaryotic RNA viruses may outnumber prokaryotic RNA viruses by nearly three times in this grassland. Of the identified eukaryotic RNA viruses and the associated eukaryotic species, the most dominant taxa were Mitoviridae with an average relative abundance of 72.4%, and their natural hosts, Fungi with an average relative abundance of 56.6%. Network analysis and structural equation modeling support that soil water content, plant presence, and type of cultivar individually demonstrate a significant positive impact on eukaryotic RNA viral richness directly as well as indirectly on eukaryotic RNA viral abundance via influencing the co-existing eukaryotic members. A significant negative influence of soil depth on soil eukaryotic richness and abundance indirectly impacts soil eukaryotic RNA viral communities. These results provide new insights into the collective influence of multiple environmental and community factors that shape soil RNA viral communities and offer a structured perspective of how RNA virus diversity and ecology respond to environmental changes. IMPORTANCE: Climate change has been reshaping the soil environment as well as the residing microbiome. This study provides field-relevant information on how environmental and community factors collectively shape soil RNA communities and contribute to ecological understanding of RNA viral survival under various environmental conditions and virus-host interactions in soil. This knowledge is critical for predicting the viral responses to climate change and the potential emergence of biothreats.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA