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1.
J Mol Diagn ; 26(7): 638-651, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38663495

RESUMO

Noninvasive prenatal diagnosis (NIPD) for autosomal recessive nonsyndromic hearing loss (ARNSHL) has been rarely reported until recent years. Additionally, the existing method can not be used for challenging genome loci (eg, copy number variations, deletions, inversions, or gene recombinants) or on families without proband genotype. This study assessed the performance of relative haplotype dosage analysis (RHDO)-based NIPD for identifying fetal genotyping in pregnancies at risk of ARNSHL. Fifty couples carrying pathogenic variants associated with ARNSHL in either GJB2 or SLC26A4 were recruited. The RHDO-based targeted linked-read sequencing combined with whole gene coverage probes was used to genotype the fetal cell-free DNA of 49 families who met the quality control standard. Fetal amniocyte samples were genotyped using invasive prenatal diagnosis (IPD) to assess the performance of NIPD. The NIPD results showed 100% (49/49) concordance with those obtained through IPD. Two families with copy number variation and recombination were also successfully identified. Sufficient specific informative single-nucleotide polymorphisms for haplotyping, as well as the fetal cell-free DNA concentration and sequencing depth, are prerequisites for RHDO-based NIPD. This method has the merits of covering the entire genes of GJB2 and SLC26A4, qualifying for copy number variation and recombination analysis with remarkable sensitivity and specificity. Therefore, it has clinical potential as an alternative to traditional IPD for ARNSHL.


Assuntos
Alelos , Conexina 26 , Haplótipos , Transportadores de Sulfato , Humanos , Transportadores de Sulfato/genética , Feminino , Gravidez , Polimorfismo de Nucleotídeo Único , Teste Pré-Natal não Invasivo/métodos , Conexinas/genética , Diagnóstico Pré-Natal/métodos , Variações do Número de Cópias de DNA , Surdez/genética , Surdez/diagnóstico , Genótipo , Masculino , Genes Recessivos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Proteínas de Membrana Transportadoras/genética
2.
Front Med (Lausanne) ; 10: 1171819, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37534312

RESUMO

Background: Photodynamic therapy (PDT) promotes significant tumor regression and extends the lifetime of patients. The actual operation of PDT often relies on the subjective judgment of experienced neurosurgeons. Patients can benefit more from precisely targeting PDT's key operating zones. Methods: We used magnetic resonance imaging scans and created 3D digital models of patient anatomy. Multiple images are aligned and merged in STL format. Neurosurgeons use HoloLens to import reconstructions and assist in PDT execution. Also, immunohistochemistry was used to explore the association of hyperperfusion sites in PDT of glioma with patient survival. Results: We constructed satisfactory 3D visualization of glioma models and accurately localized the hyperperfused areas of the tumor. Tumor tissue taken in these areas was rich in CD31, VEGFA and EGFR that were associated with poor prognosis in glioma patients. We report the first study using MR technology combined with PDT in the treatment of glioma. Based on this model, neurosurgeons can focus PDT on the hyperperfused area of the glioma. A direct benefit was expected for the patients in this treatment. Conclusion: Using the Mixed Reality technique combines multimodal imaging signatures to adjuvant glioma PDT can better exploit the vascular sealing effect of PDT on glioma.

3.
Microorganisms ; 10(12)2022 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-36557725

RESUMO

To improve the application of endophyte Bacillus velezensis BY6 from the xylem of poplar, the effect of BY6 on the growth of diseased Populus davidiana × Populus. alba var. pyramidalis Louche (Pdpap poplar) seedlings and the biological control effect on the pathogen Armillaria solidipes were tested using a plant split-root experiment. After applying BY6 to the roots of diseased Pdpap poplar seedlings, the results show that plant growth indicators (dry mass, fresh mass, and plant height) were significantly increased (p < 0.05), and genes related to auxin hormone signal transcription were activated. BY6 indicated a surprising control effect after the inoculation of diseased Pdpap poplar seedlings. Compared to the infected control group, the treated disease index of the diseased Pdpap poplar seedlings in the treatment group were reduced by 49.53% on the 20th day. The relative staining areas of diaminobenzidine (DAB) and Trypan blue decreased by 3.37 and 7.31 times, respectively. The physiological indicators (soluble sugar and protein) and oxidase indicators were significantly increased (p < 0.05). The expression levels of defense genes related to salicylic acid (SA) and jasmonic acid (JA) signaling pathways were significantly increased (p < 0.05). Amazingly, the results indicate that BY6 simultaneously activates induced systemic resistance (ISR) and systemic acquired resistance (SAR) in diseased Pdpap poplar seedlings and promotes growth. The results indicate that BY6 is a promising candidate for developing forest tree biofertilizers and biopesticides.

4.
Biomed Res Int ; 2021: 3904120, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33604372

RESUMO

An endophytic bacterium Bacillus velezensis BY6 was isolated from the wood stems of healthy Populus davidiana × P. alba var. pyramidalis (PdPap). The BY6 strain can inhibit pathogenic fungus Alternaria alternate in PdPap and promote growth of PdPap seedlings. In the present study, we used the Pacific Biosciences long-read sequencing platform, a single-molecule real-time (SMRT) technology for strain BY6, to perform complete genome sequencing. The genome size was 3,898,273 bp, the number of genes was 4,045, and the average GC content was 47.33%. A complete genome of strain BY6 contained 110 secondary metabolite gene clusters. Nine of the secondary metabolite gene clusters exhibited antifungal activity and promoted growth functions primarily involved in the synthesis of surfactin, bacteriocins, accumulated iron ions, and related antibiotics. Gene clusters provide genetic resources for biotechnology and genetic engineering, and enhance understanding of the relationship between microorganisms and plants.


Assuntos
Antifúngicos , Bacillus/genética , Genoma Bacteriano/genética , Reguladores de Crescimento de Plantas , Antifúngicos/metabolismo , Antifúngicos/farmacologia , Bacillus/metabolismo , Bacillus/fisiologia , Composição de Bases/genética , Endófitos/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Reguladores de Crescimento de Plantas/farmacologia , Populus/microbiologia , Madeira/microbiologia
5.
BMJ Open ; 10(12): e040137, 2020 12 29.
Artigo em Inglês | MEDLINE | ID: mdl-33376163

RESUMO

OBJECTIVE: Emerging evidence from observational studies (cohort and case-control studies) suggests that a history of diabetes mellitus (DM) has been linked to increased risk of ovarian cancer (OC), but the association between them remains inconclusive. The aim of this systematic review and meta-analysis of observational studies was to clarify this association. DESIGN: Systematic review and meta-analysis. METHODS: We searched PubMed, Embase and the Cochrane library databases published from the inception through 9 April 2020 without language restriction. Observational studies that evaluated the correlation between DM and the incidence of OC were included in our study. Relative risk (RR) with 95% CI was pooled by use of a random-effects model. RESULTS: A total of 36 epidemiological articles, including 9 case-control and 27 cohort studies, were finally enrolled, consisting of 14 496 incident cases of OC. Synthesised RRs of developing OC by history of DM were 1.20 (95% CI=1.10 to 1.31) for all eligible studies, 1.08 (95% CI=0.77 to 1.53) for case-control studies and 1.22 (95% CI=1.11 to 1.33) for cohort studies. The above-mentioned positive association persisted across most of subgroup analyses, whereas it was not significant among studies from North American and European countries, level of unadjusted, and patients with low-quality and gestational DM group. The cumulative meta-analysis and sensitivity analysis showed pooled effect was stable and reliable, and no apparent publication bias was identified in this study. CONCLUSIONS: Our study found weaker but still association between DM and OC risk. However, further well-designed prospective studies that control for potential confounders are warranted.


Assuntos
Diabetes Mellitus , Neoplasias Ovarianas , Estudos de Casos e Controles , Estudos de Coortes , Complicações do Diabetes , Diabetes Mellitus/epidemiologia , Europa (Continente) , Feminino , Humanos , Neoplasias Ovarianas/epidemiologia , Neoplasias Ovarianas/etiologia , Estudos Prospectivos , Fatores de Risco
6.
Polymers (Basel) ; 11(5)2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31052412

RESUMO

In this study, jute fabrics were used to reinforce epoxy resin to prepare laminated composites. KH-560 silane coupling agent modification was used to improve the interfacial compatibility between fibers and epoxy. The effects of different immersion times (0 min, 10 min, 30 min, 60 min, 90 min, and 120 min) on the jute fiber's element content, crystal structure, and thermal stability, and the mechanical properties of laminated composites were studied. X-ray diffractometry (XRD) analysis showed that the KH-560 modification improved the crystallinity index (CI) and crystallite sizes (CS) of jute fibers. Scanning electron microscopy (SEM) analysis of the tensile fracture surfaces revealed a thick epoxy on the modified pulled fiber surfaces. Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectrometer (EDS) analysis identified the presence of silicon and C-O-Si/Si-O-Si cross-linked structures on the surface of modified jute fibers. These cross-linked structures improved the thermal stability and mechanical properties of the laminated composites. When the immersion time was 60 min, the CI, CS, tensile strength, tensile modulus, flexural strength, and flexural modulus of the modified samples were 42.39%, 3.62 nm, 34.6 ± 1.1 MPa, 2.11 ± 0.12 GPa, 83.7 ± 1.8 MPa, and 4.08 ± 0.12 GPa, respectively, which were better than that of unmodified and other modified composites.

7.
Materials (Basel) ; 12(9)2019 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-31035442

RESUMO

In this study, jute fabrics/epoxy-laminated composites were fabricated via a simple and effective manual layering. Hot-alkali treatment was used to pretreat jute fabrics to improve their interfacial compatibility. The effects of hot-alkali treatment with five concentrations (2%, 4%, 6%, 8% and 10%) on the composition, crystallinity and surface morphology of jute fibers, were analyzed with the aids of Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and the scanning electron microscope (SEM). The mechanical properties (tensile and flexural) of laminated composites, and the morphology of the tensile fracture surface, were analyzed. The results indicated that the crystallinity index (CI) and crystallite size (CS) of the cellulose in jute fibers were improved, and there were three stages for CI and CS with the increase of alkali concentrations. Hot-alkali treatment improved the mechanical properties of laminated composites, especially for the 6% NaOH-treated jute fabric reinforced. The tensile strength, flexural strength, tensile modulus and flexural modulus of 6% NaOH-treated fabrics reinforced composites were enhanced by 37.5%, 72.3%, 23.2% and 72.2%, respectively, as compared with those of untreated fabrics reinforced composites. The fiber pull-out and the gaps of the tensile fracture surface were reduced after hot-alkali treatment.

8.
PeerJ ; 7: e6444, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30863670

RESUMO

BACKGROUND: To ensure the safety of trees, two NDT (nondestructive testing) techniques, electric resistance tomography and stress wave tomography, were employed to quantitatively detect and characterize the internal decay of standing trees. Comparisons between those two techniques were done to make full use of the individual capability for decay detection. METHODS: Eighty trees (40 Manchurian ash and 40 Populus simonii) were detected, then wood increment cores were obtained from each cross disc trial. The D t , which was defined as the value determined by the mass loss ratio of each wood core, was regarded as the true severity of decay. Using ordinary least-squares regression to analyze the relationship between D t and D e (D e was defined as the severity of decay determined by electric resistance tomography) and between D t and D s (D s was defined as the severity of decay determined by stress wave tomography). RESULTS: The results showed that both methods could estimate the severity of decay in trees. In terms of different stages of decay, when D t < 30%, D e had a strong positive correlation with D t (R 2 = 0.677, P < 0.01), while, when D t ≥ 30%, D s had a significant positive correlation relationship with D t (R 2 = 0.645, P < 0.01). CONCLUSION: Electric resistance tomography was better than stress wave tomography for testing in the early stages of decay, while stress wave tomography can be used effectively in the late stage of decay. It is suggested that each technique can be used in the practice of internal decay testing of standing trees based on decay stages and operating conditions.

9.
Sci Rep ; 7(1): 12735, 2017 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-28986572

RESUMO

We investigate using scanning tunneling microscopy and spectroscopy electronic aspects of Moiré superstructures in nanoscale Pb quantum films grown on IrTe2, which is a unique layered material with charge-order transitions into stripe phases. Pb ultrathin films exhibit a Moiré superstructure due to the lattice mismatch of Pb and IrTe2, which produces strong lateral electronic modulation of hexagonal symmetry and discreet subbands. Moreover, strongly anisotropic or 1D electronic states are formed in Pb films as modulated by the stripe charge order. Present results indicate the controllability of lateral electronic structures of various ultrathin films by extra interfacial potentials due not only to Moiré superstructures but also to novel electronic orderings of substrates.

10.
Nat Commun ; 8(1): 392, 2017 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-28855505

RESUMO

Domain walls in interacting electronic systems can have distinct localized states, which often govern physical properties and may lead to unprecedented functionalities and novel devices. However, electronic states within domain walls themselves have not been clearly identified and understood for strongly correlated electron systems. Here, we resolve the electronic states localized on domain walls in a Mott-charge-density-wave insulator 1T-TaS2 using scanning tunneling spectroscopy. We establish that the domain wall state decomposes into two nonconducting states located at the center of domain walls and edges of domains. Theoretical calculations reveal their atomistic origin as the local reconstruction of domain walls under the strong influence of electron correlation. Our results introduce a concept for the domain wall electronic property, the walls own internal degrees of freedom, which is potentially related to the controllability of domain wall electronic properties.The electronic states within domain walls in an interacting electronic system remain elusive. Here, Cho et al. report that the domain wall state in a charge-density-wave insulator 1T-TaS2 decomposes into two localized but nonconducting states at the center or edges of domain walls.

11.
Ying Yong Sheng Tai Xue Bao ; 27(2): 380-6, 2016 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-27396108

RESUMO

The morphological parameters, root wad indexes and site conditions of 127 uprooting trees from 76 plots (20 mx20 m) in Lesser Khingan coniferous-broad leaved Korean pine mixed forest were measured. Then the influencing factors of uprooting differences and the relationship between uprooting trees and disturbed soil were analyzed. Results showed that the number of uprooting trees varied significantly among species. Abies nephrolepis suffered the most serious uprooting damage, then Pinus koraiensis, and Ulmus spp. the least. Deciduous species had a stronger uprooting-resistant capacity than broad-leaved species. With the increase of tree DBH and height, tree' s uprooting resistance declined rapidly first and then was gradually enhanced, and finally reached the minimum at diameter class of 20 cm and height class of 14 m, respectively. The smaller the taper degree and projected area of crown were, the stronger the uprooting resistance was. Uprooting rate was negatively correlated with stand density. Trees lying in wet ground, flat terrain, medium low altitude area and windward slope had a greater risk of uprooting. There were significant positive correlation between the depth, area and volume of disturbed soil and the DBH, height, volume of uprooting trees.


Assuntos
Florestas , Solo , Árvores/fisiologia , Abies , China , Pinus , Ulmus
12.
Nano Lett ; 16(7): 4260-5, 2016 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-27221583

RESUMO

Entanglement of charge orderings and other electronic orders such as superconductivity is in the core of challenging physics issues of complex materials including high temperature superconductivity. Here, we report on the observation of a unique nanometer scale honeycomb charge ordering of the cleaved IrTe2 surface, which hosts a superconducting state. IrTe2 was recently established to exhibit an intriguing cascade of stripe charge orders. The stripe phases coexist with a hexagonal phase, which is formed locally and falls into a superconducting state below 3 K. The atomic and electronic structures of the honeycomb and hexagon pattern of this phase are consistent with the charge order nature, but the superconductivity does not survive on neighboring stripe charge order domains. The present work provides an intriguing physics issue and a new direction of functionalization for two-dimensional materials.

13.
J Am Chem Soc ; 138(17): 5479-82, 2016 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-26927232

RESUMO

The layered perovskite Ca3-xSrxMn2O7 is shown to exhibit a switching from a material exhibiting uniaxial negative to positive thermal expansion as a function of x. The switching is shown to be related to two closely competing phases with different symmetries. The negative thermal expansion (NTE) effect is maximized when the solid solution is tuned closest to this region of phase space but is switched off suddenly on passing though the transition. Our results show for the first time that, by understanding the symmetry of the competing phases alone, one may achieve unprecedented chemical control of this unusual property.

14.
Ying Yong Sheng Tai Xue Bao ; 26(2): 349-55, 2015 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-26094446

RESUMO

Vast loss of timber resources can be reduced by preventing and controlling the decay of standing trees in forest management. Therefore, research concerning the effect of site conditions on decay of standing trees is particularly important for decay prevention and cure. A relevant study was carried out in Xiaoxing'anling Mountains on October, 2013, and thirty decayed and ten normal mature or postmature Korean pine (Pinus koraiensis) live standing trees were selected as sample trees, respectively. Two increment core samples were selected from the basal trunk of each sample tree to measure the mass loss ratio of rotted increment core samples. Meanwhile, moisture content of the soil near sample trees' roots and the gradient, exposure, slope position and elevation of the site where sample trees located were tested or measured. Analysis was made upon the relationship between factors such as sapwood and heartwood moisture contents and the decay of sample trees by correlation analysis and analysis of variance. The results indicated that moisture content of the sapwood negatively correlated with the decay degree of Korean pine live standing trees at a very significant level, so did the heartwood moisture content. Soil moisture content had a positive correlation with the decay degree at a highly significant level. Significant differences in the moisture contents of sapwood, heartwood and soils were observed between decayed and normal sample trees. Slope position was the only factor that had a significant effect on the decay degree among all the three slope factors. The decay degree of live standing trees on the middle part of slopes was significantly higher than that on the upper part of slope, mainly due to the significantly higher soil moisture content on the middle part of slope. Elevation of the site where sample trees located had no significant correlation with the decay degree of Korean pine.


Assuntos
Agricultura Florestal , Florestas , Pinus , Água , Solo , Árvores , Madeira
15.
Ying Yong Sheng Tai Xue Bao ; 24(7): 1837-42, 2013 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-24175511

RESUMO

Standing trees decay often causes vast loss of timber resources. To investigate the correlations between the standing trees decay and the site conditions is of importance to scientifically and reasonably manage forests and to decrease wood resources loss. By using Resistograph and meter ruler, a measurement was made on the decay degree of the trunk near root and the diameter at breast height (DBH) of 15 mature Korean pine standing trees in a Korean pine-broadleaved mixed forest in Xiao Xing' an Mountains in May, 2011. In the meantime, soil samples were collected from the root zones of standing trees and the upslope and downslope 5 meters away from the trunks, respectively. Five physical-chemical properties including moisture content, bulk density, total porosity, pH value, and organic matter content of the soil samples were tested. The regression equations concerning the trunk decay degree of the standing trees, their DBH, and the 5 soil properties were established. The results showed that the trunk decay degree of the mature Korean pine standing trees had higher correlations with the bulk density, total porosity, pH value, and organic matter content (R = 0.687), and significant positive correlation with the moisture content (R = 0.507) of the soils at the root zones of standing trees, but less correlation with the 5 properties of the soils at both upslope and downslope 5 meters away from the trunks. The trunk decay degree was decreased when the soil moisture content was below 18.4%. No significant correlation was observed between the trunk decay degree of mature Korean pine standing trees and the tree age.


Assuntos
Fenômenos Químicos , Florestas , Pinus/crescimento & desenvolvimento , Doenças das Plantas , Árvores/crescimento & desenvolvimento , China , Conservação dos Recursos Naturais , Doenças das Plantas/etiologia , Caules de Planta/crescimento & desenvolvimento , Solo/química , Água/análise
16.
Ying Yong Sheng Tai Xue Bao ; 24(11): 3043-9, 2013 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-24564130

RESUMO

Taking the Korean pine broadleaved forest in Liangshui Nature Reserve of Heilongjiang Province, Northeast China as test object, this paper studied the species composition and diameter class structure, and by using point pattern analysis, analyzed the spatial distribution pattern and spatial association of the main populations. In the Reserve, there were a total of 16 species with diameter greater than 1 cm in tree layer, and great differences were observed in the densities of main populations. Coniferous trees such as Pinus koraiensis and Abies nephrolepis were dominant. The diameter class structure of the populations presented as an inverse "J" curve, indicating a good regeneration across the community. The main populations were mostly in aggregated distribution pattern, except that the P. koraiensis populations at the scales of 19-21 m and 44 m as well as the Acer tegmentosum populations close to the largest research scale were in random distribution. The P. koraiensis populations at all research scales were approximately in random distribution, and had the minimum aggregation. A. nephrolepis, Tilia amurensis, and A. tegmentosum populations all presented a random distribution trend. Except that the P. koraiensis and A. nephrolepis at 2-3 m scale and the A. nephrolepis and A. tegmentosum populations at 37-81 m scale had significant positive association, no significant associations were observed between other populations. All the tree species presented an overall non-significant positive association.


Assuntos
Conservação dos Recursos Naturais , Florestas , Pinus/crescimento & desenvolvimento , Árvores/classificação , Abies/crescimento & desenvolvimento , China , Pinus/anatomia & histologia , Dinâmica Populacional , Análise Espacial , Tilia/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento
17.
Ying Yong Sheng Tai Xue Bao ; 21(12): 3070-6, 2010 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-21442991

RESUMO

Taking the Larix gmellinii plantation in the experimental forest farm of Northeast Forestry University as test object, and by using Li-8100 automatic instrument, the daily CO2 emission rate of soil in summer under different degrees of man-made compaction was measured, with the regression models established. There were significant differences in the diurnal variation of soil respiration rate under different degrees of man-made compaction. In CK (no compaction), the maximum value of soil respiration appeared at 15:30-17:30, and the minimum value appeared at 03:30-05:30, which were obviously lagged behind those in compaction treatments. The maximum and minimum values of soil respiration rate in main roads appeared at 09:30-11:30 and 23:30-01:30, and those in branch roads appeared at 11:30 and 01:30-03:30, respectively. In all treatments, soil respiration rate had significant correlations with surface temperature, relative humidity, and the temperature at 10 cm soil depth, but the correlation with the soil moisture at 5 cm depth tended to be not significant when the compaction degree was increasing. Compaction altered surface soil physical structure, decreased surface soil CO2 release rate.


Assuntos
Dióxido de Carbono/análise , Atividades Humanas , Larix/fisiologia , Solo/análise , Respiração Celular , Ritmo Circadiano , Cidades , Estações do Ano
18.
Ying Yong Sheng Tai Xue Bao ; 19(4): 729-34, 2008 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-18593029

RESUMO

By using LI-8100 CO2 Flux Meter, the CO2 flux of soil surface and the temperature and moisture content at soil depth of 10 cm in conifer/broad-leaved mixed forests under different intensity of selective cutting in Dailing Forest Bureau of Heilongjiang Province were determined simultaneously from 2003 to 2007, with the changes of soil surface CO2 flux after selective cutting and their affecting factors studied. The results showed that the CO2 flux was correlated with soil temperature and moisture content, with a relatively high confidence ranged from 68% to 98%. Selective cutting increased the CO2 flux, with an average annual increment being from 7.17% to 26.89%. There was a significant quadratic correlation between soil surface CO2 flux and cutting intensity (R2 = 0.961). Soil organic matter content and cutting intensity were the main factors affecting the changes of soil surface CO2 flux after selective cutting.


Assuntos
Dióxido de Carbono/metabolismo , Raízes de Plantas/fisiologia , Solo/análise , Traqueófitas/fisiologia , Árvores/fisiologia , Respiração Celular , China , Ecossistema , Agricultura Florestal/métodos , Raízes de Plantas/metabolismo , Microbiologia do Solo , Traqueófitas/metabolismo , Árvores/metabolismo
19.
Ying Yong Sheng Tai Xue Bao ; 19(2): 261-6, 2008 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-18464629

RESUMO

Based on Landsat TM images and with the natural forest area of Wangqing in Jilin Province as a case, a nonlinear RS (remote sensing) modeling system of forest biomass was built by using a back-propogation artificial neural network (B-P ANN). In addition to RS data, the factors representing terrain conditions, such as elevation, slope, aspect and site type, were also included as independent variables in the modeling system. The standard B-P ANN was made more robust by reducing the size of input data and by improving the training algorithms, thereby leading to faster convergence speed and stronger capabilities of self-study and self-adaptation. The simulation results showed that the robust B-P ANN was able to utilize previous knowledge of data sets, and to automatically determine reasonable models. Model predictions of forest biomass were successful, with the mean relative errors and the mean absolute of relative errors for needle-leaved, broad-leaved, and mixed forests being -1.47%, 2.38% and 3.56%, and 6.33%, 8.46% and 8.91% , respectively. A forest biomass distribution map was derived, and the overall accuracy of the map was 88.04%.


Assuntos
Biomassa , Redes Neurais de Computação , Árvores/crescimento & desenvolvimento , China , Geografia , Modelos Teóricos , Comunicações Via Satélite
20.
Ying Yong Sheng Tai Xue Bao ; 18(1): 1-8, 2007 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-17396491

RESUMO

Forest biomass estimation is the groundwork of analyzing carbon cycle and its dynamics in terrestrial ecosystems, but the current estimation models had the problem of un-compatibility between total forest biomass and its components. Taking the Wangqing natural forest area in Jilin Province as a case, the compatible concept of building forest biomass models based on forest invent' tory was brought forward. A series of compatible biomass estimation models, taking stem volume as one of the independent variables, were established by using simultaneous equations. The accuracy of the models in estimating the biomass of coniferous forest, broad-leaved forest, and mixed forest was all higher than 95% , suggesting that these models basically solved the problem of un-compatibility between total forest biomass and its components.


Assuntos
Biomassa , Conservação dos Recursos Naturais , Monitoramento Ambiental/métodos , Modelos Teóricos , Árvores/crescimento & desenvolvimento , China , Previsões , Modelos Estatísticos
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