Objective To observe changes of plain MR T1WI signal intensity of dentate nucleus in nasopharyngeal carcinoma patients after radiotherapy and multiple times of intravenous injection of gadolinium-based contrast agent(...Objective To observe changes of plain MR T1WI signal intensity of dentate nucleus in nasopharyngeal carcinoma patients after radiotherapy and multiple times of intravenous injection of gadolinium-based contrast agent(GBCA).Methods Fifty patients with pathologically confirmed nasopharyngeal carcinoma and received intensity-modulated radiotherapy were retrospectively enrolled as the nasopharyngeal carcinoma group,and 50 patients with other malignant tumors and without history of brain radiotherapy were retrospectively enrolled as the control group.All patients received yearly GBCA enhanced MR examinations for the nasopharynx or the head.T1WI signal intensities of the dentate nucleus and the pons on same plane were measured based on images in the year of confirmed diagnosis(recorded as the first year)and in the second to the fifth years.T1WI signal intensity ratio of year i(ranging from 1 to 5)was calculated with values of dentate nucleus divided by values of the pons(ΔSI i),while the percentage of relative changes of year j(ranging from 2 to 5)was calculated withΔSI j compared toΔSI 1(Rchange j).The values of these two parameters were compared,and the correlation ofΔSI and GBCA injection year-time was evaluated within each group.Results No significant difference of gender,age norΔSI 1 was found between groups(all P>0.05).The second to the fifth yearΔSI and Rchange in nasopharyngeal carcinoma group were all higher than those in control group(all P<0.05).Within both groups,ΔSI was positively correlated with GBCA injection year-time(both P<0.05).Conclusion Patients with nasopharyngeal carcinoma who underwent radiotherapy and multiple times of intravenous injection of GBCA tended to be found with gradually worsening GBCA deposition in dentate nucleus,for which radiotherapy might be a risk factor.展开更多
Clothing attribute recognition has become an essential technology,which enables users to automatically identify the characteristics of clothes and search for clothing images with similar attributes.However,existing me...Clothing attribute recognition has become an essential technology,which enables users to automatically identify the characteristics of clothes and search for clothing images with similar attributes.However,existing methods cannot recognize newly added attributes and may fail to capture region-level visual features.To address the aforementioned issues,a region-aware fashion contrastive language-image pre-training(RaF-CLIP)model was proposed.This model aligned cropped and segmented images with category and multiple fine-grained attribute texts,achieving the matching of fashion region and corresponding texts through contrastive learning.Clothing retrieval found suitable clothing based on the user-specified clothing categories and attributes,and to further improve the accuracy of retrieval,an attribute-guided composed network(AGCN)as an additional component on RaF-CLIP was introduced,specifically designed for composed image retrieval.This task aimed to modify the reference image based on textual expressions to retrieve the expected target.By adopting a transformer-based bidirectional attention and gating mechanism,it realized the fusion and selection of image features and attribute text features.Experimental results show that the proposed model achieves a mean precision of 0.6633 for attribute recognition tasks and a recall@10(recall@k is defined as the percentage of correct samples appearing in the top k retrieval results)of 39.18 for composed image retrieval task,satisfying user needs for freely searching for clothing through images and texts.展开更多
A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetr...A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetry and SA effect through polarization-maintaining erbium-doped fiber(PM-EDF)Sagnac loop,which is composed of a PM-EDF,a coupler and two polarization controllers(PCs).By using the inherent birefringence characteristic of PM-EDF,two feedback loops in orthogonal polarization state are formed when the Strokes signal in injected.One of these loops provides gain in the clockwise direction with in the Sagnac loop,while the other loop generates loss in the counterclockwise direction.By adjusting the PCs to control the polarization state of the PM-EDF,a single-longitudinal-mode(SLM)BFL can be achieved,as the PT symmetry is broken when the SA participating stimulated Brillouin scattering(SBS)gain and loss are well-matched and the gain surpasses the coupling coefficient.Compared to previous BFLs,the proposed BFL has a more streamlined structure and a wider wavelength tunable range,at the same time,it is not being limited by the bandwidth of the erbium-doped fiber amplifier while still maintaining narrow linewidth SLM output.Additionally,thanks to SA effect of the PM-EDF,the PT symmetric SBS gain contract is enhanced,resulting in a higher optical signal-to-noise(OSNR).The experimental results show that the laser has a wide tunable range of 1526.088 nm to 1565.498 nm,an improved OSNR of 77 dB,and a fine linewidth as small as 140.5 Hz.展开更多
Psychological studies on human subjects show that contrast detection learning promote learner's sensitivity to visual stimulus contrast. The underlying neural mechanisms remain unknown. In this study, three cats (Fe...Psychological studies on human subjects show that contrast detection learning promote learner's sensitivity to visual stimulus contrast. The underlying neural mechanisms remain unknown. In this study, three cats (Felis catus) were trained to perform monocularly a contrast detection task by two-altemative forced choice method. The perceptual ability of each cat improved remarkably with learning as indicated by a significantly increased contrast sensitivity to visual stimuli. The learning effect displayed an evident specificity to the eye employed for learning but could partially transfer to the naive eye, prompting the possibility that contrast detection learning might cause neural plasticity before and after the information from both eyes are merged in the visual pathway. Further, the contrast sensitivity improvement was evident basically around the spatial frequency (SF) used for learning, which suggested that contrast detection learning effect showed, to some extent, a SF specificity. This study indicates that cat exhibits a property of contrast detection learning similar to human subjects and can be used as an animal model for subsequent investigations on the neural correlates that mediate learning-induced contrast sensitivity improvement in humans.展开更多
Psychophysical experiments on human and animal subjects have proven that aged individuals show significantly reduced visual contrast sensitivity compared with young adults.To uncover the possible neural mechanisms,we ...Psychophysical experiments on human and animal subjects have proven that aged individuals show significantly reduced visual contrast sensitivity compared with young adults.To uncover the possible neural mechanisms,we used extracellular single-unit recording techniques to examine the response of V1(primary visual cortex) neurons as a function of visual stimulus contrast in both old and young adult cats(Felis catus).The mean contrast sensitivity of V1 neurons to visual stimuli in old cats decreased significantly relative to young adult cats,consistent with findings reported in old primates.These results indicate that aging can affect contrast sensitivity of visual cortical cells in both primate and non-primate mammalian animals,and might contribute to the reduction of perceptual visual contrast sensitivity in aged individuals.Further,V1 cells of old cats exhibited increased responsiveness,decreased signal-to-noise ratio,and enlarged receptive field(RF) size compared with that of young adult cats,which indicated that decreased contrast sensitivity of V1 neurons accompanied a reduction of intracortical inhibition during senescence.展开更多
[Objective] The aim was to identify genetic variation in Citrus sinensis (sweet orange) germplasm from Hunan Province according to the Start Codon Targeted (SCoT) Polymorphism. [Method] The reaction system for SCo...[Objective] The aim was to identify genetic variation in Citrus sinensis (sweet orange) germplasm from Hunan Province according to the Start Codon Targeted (SCoT) Polymorphism. [Method] The reaction system for SCoT amplification from sweet orange was first optimized, and then the SCoT fragments were amplified from 24 sweet orange cultivars collected in Hunan Province and sequenced for genetic variation analysis. [Result] The optimum reaction system for SCoT markers amplification was 2.0 μl containing 80 ng of template DNA, 0.3 mmol/L dNTPs, 0.2 μmol/L primer, 1.6 mmol/L Mg2+, 1.6 U of Taq DNA polymerase and 10×PCR buffer. By using this reaction system, the PCR products from the sweet orange cultivars produced clear and reproducible bands at 100-2 000 bp through electrophoresis. The SCoT fragments of the 24 sweet orange cultivars were 1 090-1 091 bp, with the homology of 99.84% and nucleotide deletion and substitution. After being sequenced, the SCoT polymorphisms could distinguish 12 sweet orange cultivars. In addition, the BLAST result showed that part of the SCoT fragments coding region shared high homology with ribosomal protein S3 N superfamily. [Conclusion] This study will provide a theoretical basis for breeding sweet orange cultivars.展开更多
In order to further study the postpartum care technology of dairy cows,the effects of oral administration of propylene glycol or Ca-P-Mg mixture and compound oral rehydration salts on milk quality and SCC of dairy cow...In order to further study the postpartum care technology of dairy cows,the effects of oral administration of propylene glycol or Ca-P-Mg mixture and compound oral rehydration salts on milk quality and SCC of dairy cows after birth were investigated. The results showed that the milk fat and dry matter contents in the dairy cows administered with Ca-P-Mg mixture and compound oral rehydration salts were higher than those in the dairy cows administered with propylene glycol(P 〈0.05). However, there were no significant differences in milk sugar and protein contents and SCC between the two administration groups.展开更多
The damage or loss of urban road manhole covers may cause great risk to residents' lives and property if they cannot be discovered in time. Most existing research recommendations for solving this problem are difficul...The damage or loss of urban road manhole covers may cause great risk to residents' lives and property if they cannot be discovered in time. Most existing research recommendations for solving this problem are difficult to implement. This paper proposes an algorithm that combines the improved Hough transform and image comparison to identify the damage or loss of the manhole covers in complicated surface conditions by using existing urban road video images. Focusing on the pre-processed images, the edge contour tracking algorithm is applied to find all of the edges. Then with the improved Hough transformation, color recognition and image matching algorithm, the manhole cover area is found and the change rates of the manhole cover area are calculated. Based on the threshold of the change rates, it can be determined whether there is potential damage or loss in the manhole cover. Compared with the traditional Hough transform, the proposed method can effectively improve the processing speed and reduce invalid sampling and accumulation. Experimental results indicate that the proposed algorithm has the functions of effective positioning and early warning in the conditions of complex background, different perspectives, and different videoing time and conditions, such as when the target is partially covered.展开更多
To improve the performance of Saitou and Nei's algorithm (SN) and Studier and Keppler's improved algorithm (SK) for constructing neighbor-joining phylogenetic trees and reduce the time complexity of the computat...To improve the performance of Saitou and Nei's algorithm (SN) and Studier and Keppler's improved algorithm (SK) for constructing neighbor-joining phylogenetic trees and reduce the time complexity of the computation, a fast algorithm is proposed. The proposed algorithm includes three techniques. First, a linear array A[N] is introduced to store the sum of every row of the distance matrix (the same as SK), which can eliminate many repeated computations. Secondly, the value of A [i] is computed only once at the beginning of the algorithm, and is updated by three elements in the iteration. Thirdly, a very compact formula for the sum of all the branch lengths of operational taxonomic units (OTUs) i and j is designed, and the correctness of the formula is proved. The experimental results show that the proposed algorithm is from tens to hundreds times faster than SN and roughly two times faster than SK when N increases, constructing a tree with 2 000 OTUs in 3 min on a current desktop computer. To earn the time with the cost of the space and reduce the computations in the innermost loop are the basic solutions for algorithms with many loops.展开更多
We present a new multi-scale geometrical analysis method for ophthalmic image contrast enhancement based on the contourlet transform. The contourlet transform has better performance in representing edges than wavelets...We present a new multi-scale geometrical analysis method for ophthalmic image contrast enhancement based on the contourlet transform. The contourlet transform has better performance in representing edges than wavelets due to its anisotropy and directionality,and is therefore well-suited for multiscale edge enhancement. We modify the contourlet coefficients in corresponding subband and take the noise into account for mere precise reconstruction and better visualization. We compare this approach with enhancement based on the ourvelet transform,and the traditional Histogram Stretching (HS). Our findings are that contourlet based enhancement out-performs other enhancement methods on low contrast and dynamic range images,and can clearly identify the vessels and nerves in an ophthalmic image.展开更多
[Objective] The molecular weight,isoelectric point,signal peptide,domain and other properties of the encoding protein of the known cystatin genes were analyzed.[Method] Cystatin genes were searched in NCBI and the rel...[Objective] The molecular weight,isoelectric point,signal peptide,domain and other properties of the encoding protein of the known cystatin genes were analyzed.[Method] Cystatin genes were searched in NCBI and the related amino acids sequences were downloaded.SMART software was used to predict the domain.SingalP program was used to search signal peptide.TMHMM program was used to search and predict the transmembrane domain.CLUSTAL W program was used to make multiple sequence alignment.Using MEGA3.1 software,...展开更多
This paper elaborated the special geological conditions of Chongqing City and the characteristics of urban bridges formed by natural environment, and put forth the ecological landscape design ideas of urban bridges. 3...This paper elaborated the special geological conditions of Chongqing City and the characteristics of urban bridges formed by natural environment, and put forth the ecological landscape design ideas of urban bridges. 3 principles of ecological landscape design were presented including paying attention to the creation of great environment, focusing on the comparison and harmony between natural and artificial factors and seeking for simple lines and unified colors, and the application of ecological landscape design principles in constructing ecological landscape of bridges in Chongqing City was analyzed. By discussing the existing problems of ecological landscape design of bridges in Chongqing City, some suggestions were summarized, which were expected to produce positive effects for the researches of ecological landscape design of bridges.展开更多
The gradient image is always sensitive to noise in image detail enhancement. To overcome this shortage, an improved detail enhancement algorithm based on difference curvature and contrast field is proposed. F...The gradient image is always sensitive to noise in image detail enhancement. To overcome this shortage, an improved detail enhancement algorithm based on difference curvature and contrast field is proposed. Firstly, the difference curvature is utilized to determine the amplification coefficient instead of the gradient. This new amplification function of the difference curvature takes more neighboring points into account, it is therefore not sensitive to noise. Secondly, the contrast field is nonlinearly amplified according to the new amplification coefficient. And then, with the enhanced contrast field, we construct the energy functional. Finally, the enhanced image is reconstructed by the variational method. Experimental results of standard testing image and industrial X-ray image show that the proposed algorithm can perform well on increasing contrast and sharpening edges of images while suppressing noise at the same time.展开更多
To investigate quantitatively one of the parametric effects——simultaneous color contrast on color appearance and color difference evaluation in complex displays, a set of center/surround combinations of color stimu...To investigate quantitatively one of the parametric effects——simultaneous color contrast on color appearance and color difference evaluation in complex displays, a set of center/surround combinations of color stimuli were displayed on a color monitor and the perceived color shifts of test targets induced by its surrounds were measured using binocular matching method while systematically varying hue difference between target and surround. When the hue difference increased, the magnitude of color shift in test target decreased, but the deflection angle of color shift vector from constant hue line increased. Regression analyses of experimental data indicated that the relationship between hue angle difference and the magnitude of perceived color shifts could be described quantitatively by an exponential function, and a linear function could describe quantitative relationship between hue angle difference and deflection angle of color shift vector from constant hue line.展开更多
[Objective] The aim was to discuss the classification of agricultural informatization in some developed countries, and conclude the revelation to Chinese agricultural informatization. [Method] The research was made by...[Objective] The aim was to discuss the classification of agricultural informatization in some developed countries, and conclude the revelation to Chinese agricultural informatization. [Method] The research was made by comparison, according to the development impetus. [Result] The results show that foreign agricultural informatization is mainly divided into three categories: the first category is the government leading; the second category is the industry self-help; the third category is typical demonstration. Since the reform and opening, Chinese agricultural informatization has made considerable achievements. [Conclusion] The agricultural informatization is significant to promote the update of the traditional agriculture, and it is also essential to Chinese agricultural sustainability.展开更多
Translation is cross-cultural activity existing between two different language signs. In the process of translating, translators can not get out of the influence of cultural elements. From the angle of cross-cultural ...Translation is cross-cultural activity existing between two different language signs. In the process of translating, translators can not get out of the influence of cultural elements. From the angle of cross-cultural pragmatic contrasting, the author makes analysis of the problems of difference existing between the volume of information borne or transmitted between two different language signs in the process of translating under the influence of cultural elements, and points out that to study these problems, translators must consider a series of problems about cross-cultural cognitive context. This article also makes cross-cultural pragmatic contrastive analysis in world view difference, register difference, imaginative difference and metaphor difference. The author introduces the method of cross-cultural pragmatic contrastive analysis and suggests taking a series of measures to improve translation education.展开更多
Based on the theory of thematic complexity, a contrastive analysis on 2 sections selected from research articles-method and discussion, was conducted. The differences and similarities between the 2 sections in simple ...Based on the theory of thematic complexity, a contrastive analysis on 2 sections selected from research articles-method and discussion, was conducted. The differences and similarities between the 2 sections in simple theme, multiple theme, textual theme, interpersonal theme, topical theme and thematic progression were analyzed and concluded. The author believes that the causes of the differences and similarities are the different genre features of the 2 sections and the academic features of the materials selected.展开更多
The author adopts the research methods of presentations → contrasts → analyses by perceiving the drawbacks of traditional Chinese grammar teaching based on her overseas study experience as well as the understanding ...The author adopts the research methods of presentations → contrasts → analyses by perceiving the drawbacks of traditional Chinese grammar teaching based on her overseas study experience as well as the understanding and study on the overseas related teaching methods, tries to use some new concepts and practice of foreign countries for reference, and works out the way to improve the traditional Chinese teaching methods.展开更多
[Objective] The aim was to identify the species diversity of Actinomycetes from Mangrove forest in Beihai,Guangxi Province. [Method] 10 strains of typical Actinomycetes were isolated from Mangrove forest soil,and the ...[Objective] The aim was to identify the species diversity of Actinomycetes from Mangrove forest in Beihai,Guangxi Province. [Method] 10 strains of typical Actinomycetes were isolated from Mangrove forest soil,and the Actinomycetes genomic DNA was successful extracted. 16S rDNA was amplified by PCR and sequenced by Sanger dideoxy sequencing method. [Result] All the sequences were blasted in genbank,eight strains belonged to the genus of Streptomyces (80%),and two strains belonged to the genus of Nocardiopsis (20%). [Conclusion] There are many different Actinomycetes species in Mangrove forest soil samples in Beihai,Guangxi Province.展开更多
Petroleum geochemistry contributes to exploration successes by providing key constraints for geological models and critical input to exploration scenarios. One of the most important tasks in a typical exploration pr...Petroleum geochemistry contributes to exploration successes by providing key constraints for geological models and critical input to exploration scenarios. One of the most important tasks in a typical exploration program is to identify the most effective source intervals or kitchens in a basin, through oil-source correlation. The results of correlation are valid only if the geochemical parameters used address adequately the genetic characteristics of the source rocks as well as the mass transport and mixing processes of hydrocarbon fluids occurring in the carrier beds and reservoirs. This manuscript discusses four of the major contentious petroleum geochemical issues in China’s sedimentary basins. It is suggested that marine incursions played a significant role in the formation of prolific petroleum source rocks in the gigantic, dominantly freshwater, Songliao Basin. Several models are proposed to account for the occurrence of immature oils in the Cathaysian rift system including the Bohai Bay Basin, thus immature source rocks are considered a mere minor contributor to the known economic immature oil resources. Both geological and geochemical evidence are reviewed to refute a dominantly coaly source for the petroleum discovered in the Turpan Basin. Results of case studies are presented to demonstrate the importance of recognizing petroleum fluid mixing to solve the oil-source correlation issues in the structurally complex Tarim Basin. In addressing the fundamental assumptions and potential flaws of the molecular geochemical parameters commonly used for oil-source correlation, the need of a mass fraction approach is proposed to deal with such contentious issues as marine versus lacustrine, coal versus lacustrine, and mature versus immature oils.展开更多
文摘Objective To observe changes of plain MR T1WI signal intensity of dentate nucleus in nasopharyngeal carcinoma patients after radiotherapy and multiple times of intravenous injection of gadolinium-based contrast agent(GBCA).Methods Fifty patients with pathologically confirmed nasopharyngeal carcinoma and received intensity-modulated radiotherapy were retrospectively enrolled as the nasopharyngeal carcinoma group,and 50 patients with other malignant tumors and without history of brain radiotherapy were retrospectively enrolled as the control group.All patients received yearly GBCA enhanced MR examinations for the nasopharynx or the head.T1WI signal intensities of the dentate nucleus and the pons on same plane were measured based on images in the year of confirmed diagnosis(recorded as the first year)and in the second to the fifth years.T1WI signal intensity ratio of year i(ranging from 1 to 5)was calculated with values of dentate nucleus divided by values of the pons(ΔSI i),while the percentage of relative changes of year j(ranging from 2 to 5)was calculated withΔSI j compared toΔSI 1(Rchange j).The values of these two parameters were compared,and the correlation ofΔSI and GBCA injection year-time was evaluated within each group.Results No significant difference of gender,age norΔSI 1 was found between groups(all P>0.05).The second to the fifth yearΔSI and Rchange in nasopharyngeal carcinoma group were all higher than those in control group(all P<0.05).Within both groups,ΔSI was positively correlated with GBCA injection year-time(both P<0.05).Conclusion Patients with nasopharyngeal carcinoma who underwent radiotherapy and multiple times of intravenous injection of GBCA tended to be found with gradually worsening GBCA deposition in dentate nucleus,for which radiotherapy might be a risk factor.
基金National Natural Science Foundation of China(No.61971121)。
文摘Clothing attribute recognition has become an essential technology,which enables users to automatically identify the characteristics of clothes and search for clothing images with similar attributes.However,existing methods cannot recognize newly added attributes and may fail to capture region-level visual features.To address the aforementioned issues,a region-aware fashion contrastive language-image pre-training(RaF-CLIP)model was proposed.This model aligned cropped and segmented images with category and multiple fine-grained attribute texts,achieving the matching of fashion region and corresponding texts through contrastive learning.Clothing retrieval found suitable clothing based on the user-specified clothing categories and attributes,and to further improve the accuracy of retrieval,an attribute-guided composed network(AGCN)as an additional component on RaF-CLIP was introduced,specifically designed for composed image retrieval.This task aimed to modify the reference image based on textual expressions to retrieve the expected target.By adopting a transformer-based bidirectional attention and gating mechanism,it realized the fusion and selection of image features and attribute text features.Experimental results show that the proposed model achieves a mean precision of 0.6633 for attribute recognition tasks and a recall@10(recall@k is defined as the percentage of correct samples appearing in the top k retrieval results)of 39.18 for composed image retrieval task,satisfying user needs for freely searching for clothing through images and texts.
文摘A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetry and SA effect through polarization-maintaining erbium-doped fiber(PM-EDF)Sagnac loop,which is composed of a PM-EDF,a coupler and two polarization controllers(PCs).By using the inherent birefringence characteristic of PM-EDF,two feedback loops in orthogonal polarization state are formed when the Strokes signal in injected.One of these loops provides gain in the clockwise direction with in the Sagnac loop,while the other loop generates loss in the counterclockwise direction.By adjusting the PCs to control the polarization state of the PM-EDF,a single-longitudinal-mode(SLM)BFL can be achieved,as the PT symmetry is broken when the SA participating stimulated Brillouin scattering(SBS)gain and loss are well-matched and the gain surpasses the coupling coefficient.Compared to previous BFLs,the proposed BFL has a more streamlined structure and a wider wavelength tunable range,at the same time,it is not being limited by the bandwidth of the erbium-doped fiber amplifier while still maintaining narrow linewidth SLM output.Additionally,thanks to SA effect of the PM-EDF,the PT symmetric SBS gain contract is enhanced,resulting in a higher optical signal-to-noise(OSNR).The experimental results show that the laser has a wide tunable range of 1526.088 nm to 1565.498 nm,an improved OSNR of 77 dB,and a fine linewidth as small as 140.5 Hz.
基金Supported by Natural Science Foundation of Anhui Province(070413138)the foundation of Key Laboratory of Anhui Province and the Key Research Foundation from Education Department of Anhui Province(KJ2009A167)
文摘Psychological studies on human subjects show that contrast detection learning promote learner's sensitivity to visual stimulus contrast. The underlying neural mechanisms remain unknown. In this study, three cats (Felis catus) were trained to perform monocularly a contrast detection task by two-altemative forced choice method. The perceptual ability of each cat improved remarkably with learning as indicated by a significantly increased contrast sensitivity to visual stimuli. The learning effect displayed an evident specificity to the eye employed for learning but could partially transfer to the naive eye, prompting the possibility that contrast detection learning might cause neural plasticity before and after the information from both eyes are merged in the visual pathway. Further, the contrast sensitivity improvement was evident basically around the spatial frequency (SF) used for learning, which suggested that contrast detection learning effect showed, to some extent, a SF specificity. This study indicates that cat exhibits a property of contrast detection learning similar to human subjects and can be used as an animal model for subsequent investigations on the neural correlates that mediate learning-induced contrast sensitivity improvement in humans.
基金Supported by National Natural Science Foundation of China(31171082)Natural Science Foundation of Anhui Province(070413138)the Key Research Foundation of Anhui Province Education Department(KJ2009A167)
文摘Psychophysical experiments on human and animal subjects have proven that aged individuals show significantly reduced visual contrast sensitivity compared with young adults.To uncover the possible neural mechanisms,we used extracellular single-unit recording techniques to examine the response of V1(primary visual cortex) neurons as a function of visual stimulus contrast in both old and young adult cats(Felis catus).The mean contrast sensitivity of V1 neurons to visual stimuli in old cats decreased significantly relative to young adult cats,consistent with findings reported in old primates.These results indicate that aging can affect contrast sensitivity of visual cortical cells in both primate and non-primate mammalian animals,and might contribute to the reduction of perceptual visual contrast sensitivity in aged individuals.Further,V1 cells of old cats exhibited increased responsiveness,decreased signal-to-noise ratio,and enlarged receptive field(RF) size compared with that of young adult cats,which indicated that decreased contrast sensitivity of V1 neurons accompanied a reduction of intracortical inhibition during senescence.
基金Supported by National Key Technology Research and Development Program(2006BAD01A1702)~~
文摘[Objective] The aim was to identify genetic variation in Citrus sinensis (sweet orange) germplasm from Hunan Province according to the Start Codon Targeted (SCoT) Polymorphism. [Method] The reaction system for SCoT amplification from sweet orange was first optimized, and then the SCoT fragments were amplified from 24 sweet orange cultivars collected in Hunan Province and sequenced for genetic variation analysis. [Result] The optimum reaction system for SCoT markers amplification was 2.0 μl containing 80 ng of template DNA, 0.3 mmol/L dNTPs, 0.2 μmol/L primer, 1.6 mmol/L Mg2+, 1.6 U of Taq DNA polymerase and 10×PCR buffer. By using this reaction system, the PCR products from the sweet orange cultivars produced clear and reproducible bands at 100-2 000 bp through electrophoresis. The SCoT fragments of the 24 sweet orange cultivars were 1 090-1 091 bp, with the homology of 99.84% and nucleotide deletion and substitution. After being sequenced, the SCoT polymorphisms could distinguish 12 sweet orange cultivars. In addition, the BLAST result showed that part of the SCoT fragments coding region shared high homology with ribosomal protein S3 N superfamily. [Conclusion] This study will provide a theoretical basis for breeding sweet orange cultivars.
基金Supported by Technology Research,Demonstration and Promotion Project of Beijing Vocational College of Agriculture(XY-YF-14-17,XY-YF-14-11)~~
文摘In order to further study the postpartum care technology of dairy cows,the effects of oral administration of propylene glycol or Ca-P-Mg mixture and compound oral rehydration salts on milk quality and SCC of dairy cows after birth were investigated. The results showed that the milk fat and dry matter contents in the dairy cows administered with Ca-P-Mg mixture and compound oral rehydration salts were higher than those in the dairy cows administered with propylene glycol(P 〈0.05). However, there were no significant differences in milk sugar and protein contents and SCC between the two administration groups.
基金The Natural Science Fundation of Education Department of Anhui Province(No.KJ2012B051)
文摘The damage or loss of urban road manhole covers may cause great risk to residents' lives and property if they cannot be discovered in time. Most existing research recommendations for solving this problem are difficult to implement. This paper proposes an algorithm that combines the improved Hough transform and image comparison to identify the damage or loss of the manhole covers in complicated surface conditions by using existing urban road video images. Focusing on the pre-processed images, the edge contour tracking algorithm is applied to find all of the edges. Then with the improved Hough transformation, color recognition and image matching algorithm, the manhole cover area is found and the change rates of the manhole cover area are calculated. Based on the threshold of the change rates, it can be determined whether there is potential damage or loss in the manhole cover. Compared with the traditional Hough transform, the proposed method can effectively improve the processing speed and reduce invalid sampling and accumulation. Experimental results indicate that the proposed algorithm has the functions of effective positioning and early warning in the conditions of complex background, different perspectives, and different videoing time and conditions, such as when the target is partially covered.
文摘To improve the performance of Saitou and Nei's algorithm (SN) and Studier and Keppler's improved algorithm (SK) for constructing neighbor-joining phylogenetic trees and reduce the time complexity of the computation, a fast algorithm is proposed. The proposed algorithm includes three techniques. First, a linear array A[N] is introduced to store the sum of every row of the distance matrix (the same as SK), which can eliminate many repeated computations. Secondly, the value of A [i] is computed only once at the beginning of the algorithm, and is updated by three elements in the iteration. Thirdly, a very compact formula for the sum of all the branch lengths of operational taxonomic units (OTUs) i and j is designed, and the correctness of the formula is proved. The experimental results show that the proposed algorithm is from tens to hundreds times faster than SN and roughly two times faster than SK when N increases, constructing a tree with 2 000 OTUs in 3 min on a current desktop computer. To earn the time with the cost of the space and reduce the computations in the innermost loop are the basic solutions for algorithms with many loops.
文摘We present a new multi-scale geometrical analysis method for ophthalmic image contrast enhancement based on the contourlet transform. The contourlet transform has better performance in representing edges than wavelets due to its anisotropy and directionality,and is therefore well-suited for multiscale edge enhancement. We modify the contourlet coefficients in corresponding subband and take the noise into account for mere precise reconstruction and better visualization. We compare this approach with enhancement based on the ourvelet transform,and the traditional Histogram Stretching (HS). Our findings are that contourlet based enhancement out-performs other enhancement methods on low contrast and dynamic range images,and can clearly identify the vessels and nerves in an ophthalmic image.
文摘[Objective] The molecular weight,isoelectric point,signal peptide,domain and other properties of the encoding protein of the known cystatin genes were analyzed.[Method] Cystatin genes were searched in NCBI and the related amino acids sequences were downloaded.SMART software was used to predict the domain.SingalP program was used to search signal peptide.TMHMM program was used to search and predict the transmembrane domain.CLUSTAL W program was used to make multiple sequence alignment.Using MEGA3.1 software,...
文摘This paper elaborated the special geological conditions of Chongqing City and the characteristics of urban bridges formed by natural environment, and put forth the ecological landscape design ideas of urban bridges. 3 principles of ecological landscape design were presented including paying attention to the creation of great environment, focusing on the comparison and harmony between natural and artificial factors and seeking for simple lines and unified colors, and the application of ecological landscape design principles in constructing ecological landscape of bridges in Chongqing City was analyzed. By discussing the existing problems of ecological landscape design of bridges in Chongqing City, some suggestions were summarized, which were expected to produce positive effects for the researches of ecological landscape design of bridges.
基金National Natural Science Foundation of China(No.61271357)International S&T Cooperation Program of Shanxi Province(No.2013081035)
文摘The gradient image is always sensitive to noise in image detail enhancement. To overcome this shortage, an improved detail enhancement algorithm based on difference curvature and contrast field is proposed. Firstly, the difference curvature is utilized to determine the amplification coefficient instead of the gradient. This new amplification function of the difference curvature takes more neighboring points into account, it is therefore not sensitive to noise. Secondly, the contrast field is nonlinearly amplified according to the new amplification coefficient. And then, with the enhanced contrast field, we construct the energy functional. Finally, the enhanced image is reconstructed by the variational method. Experimental results of standard testing image and industrial X-ray image show that the proposed algorithm can perform well on increasing contrast and sharpening edges of images while suppressing noise at the same time.
文摘To investigate quantitatively one of the parametric effects——simultaneous color contrast on color appearance and color difference evaluation in complex displays, a set of center/surround combinations of color stimuli were displayed on a color monitor and the perceived color shifts of test targets induced by its surrounds were measured using binocular matching method while systematically varying hue difference between target and surround. When the hue difference increased, the magnitude of color shift in test target decreased, but the deflection angle of color shift vector from constant hue line increased. Regression analyses of experimental data indicated that the relationship between hue angle difference and the magnitude of perceived color shifts could be described quantitatively by an exponential function, and a linear function could describe quantitative relationship between hue angle difference and deflection angle of color shift vector from constant hue line.
文摘[Objective] The aim was to discuss the classification of agricultural informatization in some developed countries, and conclude the revelation to Chinese agricultural informatization. [Method] The research was made by comparison, according to the development impetus. [Result] The results show that foreign agricultural informatization is mainly divided into three categories: the first category is the government leading; the second category is the industry self-help; the third category is typical demonstration. Since the reform and opening, Chinese agricultural informatization has made considerable achievements. [Conclusion] The agricultural informatization is significant to promote the update of the traditional agriculture, and it is also essential to Chinese agricultural sustainability.
文摘Translation is cross-cultural activity existing between two different language signs. In the process of translating, translators can not get out of the influence of cultural elements. From the angle of cross-cultural pragmatic contrasting, the author makes analysis of the problems of difference existing between the volume of information borne or transmitted between two different language signs in the process of translating under the influence of cultural elements, and points out that to study these problems, translators must consider a series of problems about cross-cultural cognitive context. This article also makes cross-cultural pragmatic contrastive analysis in world view difference, register difference, imaginative difference and metaphor difference. The author introduces the method of cross-cultural pragmatic contrastive analysis and suggests taking a series of measures to improve translation education.
文摘Based on the theory of thematic complexity, a contrastive analysis on 2 sections selected from research articles-method and discussion, was conducted. The differences and similarities between the 2 sections in simple theme, multiple theme, textual theme, interpersonal theme, topical theme and thematic progression were analyzed and concluded. The author believes that the causes of the differences and similarities are the different genre features of the 2 sections and the academic features of the materials selected.
文摘The author adopts the research methods of presentations → contrasts → analyses by perceiving the drawbacks of traditional Chinese grammar teaching based on her overseas study experience as well as the understanding and study on the overseas related teaching methods, tries to use some new concepts and practice of foreign countries for reference, and works out the way to improve the traditional Chinese teaching methods.
基金Supported by Science Foundation of Guangxi Province (0899006)South China Agricultural University Principal Foundation ( 5100-k05099)~~
文摘[Objective] The aim was to identify the species diversity of Actinomycetes from Mangrove forest in Beihai,Guangxi Province. [Method] 10 strains of typical Actinomycetes were isolated from Mangrove forest soil,and the Actinomycetes genomic DNA was successful extracted. 16S rDNA was amplified by PCR and sequenced by Sanger dideoxy sequencing method. [Result] All the sequences were blasted in genbank,eight strains belonged to the genus of Streptomyces (80%),and two strains belonged to the genus of Nocardiopsis (20%). [Conclusion] There are many different Actinomycetes species in Mangrove forest soil samples in Beihai,Guangxi Province.
文摘Petroleum geochemistry contributes to exploration successes by providing key constraints for geological models and critical input to exploration scenarios. One of the most important tasks in a typical exploration program is to identify the most effective source intervals or kitchens in a basin, through oil-source correlation. The results of correlation are valid only if the geochemical parameters used address adequately the genetic characteristics of the source rocks as well as the mass transport and mixing processes of hydrocarbon fluids occurring in the carrier beds and reservoirs. This manuscript discusses four of the major contentious petroleum geochemical issues in China’s sedimentary basins. It is suggested that marine incursions played a significant role in the formation of prolific petroleum source rocks in the gigantic, dominantly freshwater, Songliao Basin. Several models are proposed to account for the occurrence of immature oils in the Cathaysian rift system including the Bohai Bay Basin, thus immature source rocks are considered a mere minor contributor to the known economic immature oil resources. Both geological and geochemical evidence are reviewed to refute a dominantly coaly source for the petroleum discovered in the Turpan Basin. Results of case studies are presented to demonstrate the importance of recognizing petroleum fluid mixing to solve the oil-source correlation issues in the structurally complex Tarim Basin. In addressing the fundamental assumptions and potential flaws of the molecular geochemical parameters commonly used for oil-source correlation, the need of a mass fraction approach is proposed to deal with such contentious issues as marine versus lacustrine, coal versus lacustrine, and mature versus immature oils.