Cone beam computed tomography (CBCT) is the modern third dimension applied in the field of oral maxillofacial region. With lower radiation dose compared to conventional CT, its applications in dentistry has increased ...Cone beam computed tomography (CBCT) is the modern third dimension applied in the field of oral maxillofacial region. With lower radiation dose compared to conventional CT, its applications in dentistry has increased tremendously. Artefacts can seriously degrade the quality of computed tomographic (CBCT) images, sometimes to the point of making them diagnostically unusable. To optimize image quality, it is necessary to understand why artifacts occur and how they can be prevented or suppressed. CT artifacts originate from a range of sources;physical based, scanner based and patient based. This article highlights the causes of artefacts on CBCT images and methods to avoid them.展开更多
AIM: To evaluate the value of administration of hyoscine-N-butyl-bromide (HBB) for image quality magnetic resonance imaging (MRI) of the prostate. METHODS: Seventy patients were retrospectively included in the study.... AIM: To evaluate the value of administration of hyoscine-N-butyl-bromide (HBB) for image quality magnetic resonance imaging (MRI) of the prostate. METHODS: Seventy patients were retrospectively included in the study. Thirty-five patients were examined with administration of 40 milligrams of HBB (Buscopan ; Boehringer, Ingelheim, Germany); 35 patients were examined without HBB. A multiparametric MRI protocol was performed on a 3.0 Tesla scanner without using an endorectal coil. The following criteria were evaluated independently by two experienced radiologists on a five-point Likert scale: anatomical details (delineation between peripheral and transitional zone of the prostate, visualisation of the capsule, depiction of the neurovascular bundles); visualisation of lymph nodes; motion related artefacts; and overall image quality.RESULTS: Comparison of anatomical details between the two cohorts showed no statistically significant difference (3.9 ± 0.7 vs 4.0 ± 0.9, P = 0.54, and 3.8 ± 0.7 vs 4.2 ± 0.6, P = 0.07) for both readers. There was no significant advantage regarding depiction of local and iliac lymph nodes (3.9 ± 0.6 vs 4.2 ± 0.6, P = 0.07, and 3.8 ± 0.9 vs 4.1 ± 0.8, P = 0.19). Motion arte- facts were rated as 'none' to 'few' in both groups and showed no statistical difference (2.3 ± 1.0 vs 1.9 ± 0.9, P = 0.19, and 2.3 ± 1.1 vs 1.9 ± 0.7, P = 0.22). Overall image quality was rated 'good' in average for both cohorts without significant difference (4.0 ± 0.6 vs 4.0 ± 0.9, P = 0.78, and 3.8 ± 0.8 vs 4.2 ± 0.6, P = 0.09). CONCLUSION: The results demonstrated no significant effect of HBB administration on image quality. The study suggests that use of HBB is not mandatory for MRI of the prostate at 3.0 Tesla.展开更多
X-ray analyzer-based imaging(ABI) is a powerful phase-sensitive technique that can provide a wide dynamic range of density and extract useful physical properties of the sample. It derives contrast from x-ray absorptio...X-ray analyzer-based imaging(ABI) is a powerful phase-sensitive technique that can provide a wide dynamic range of density and extract useful physical properties of the sample. It derives contrast from x-ray absorption, refraction, and scattering properties of the investigated sample. However, x-ray ABI setups can be susceptible to external vibrations, and mechanical imprecisions of system components, e.g., the precision of motor, which are unavoidable in practical experiments. Those factors will provoke deviations of analyzer angular positions and hence errors in the acquired image data.Consequently, those errors will introduce artefacts in the retrieved refraction and scattering images. These artefacts are disadvantageous for further image interpretation and tomographic reconstruction. For this purpose, this work aims to analyze image artefacts resulting from deviations of analyzer angular positions. Analytical expressions of the refraction and scattering image artefacts are derived theoretically and validated by synchrotron radiation experiments. The results show that for the refraction image, the artefact is independent of the sample’s absorption and scattering signals. By contrast, artefact of the scattering image is dependent on both the sample’s refraction and scattering signals, but not on absorption signal.Furthermore, the effect of deviations of analyzer angular positions on the accuracy of the retrieved images is investigated,which can be of use for optimization of data acquisition. This work offers the possibility to develop advanced multi-contrast image retrieval algorithms that suppress artefacts in the retrieved refraction and scattering images in x-ray analyzer-based imaging.展开更多
Objective: To propose a new method of classifying film-screen radiographic artefacts. Methodology: A prospective study was carried out at the Radiology Department of a University Teaching Hospital in Nigeria between J...Objective: To propose a new method of classifying film-screen radiographic artefacts. Methodology: A prospective study was carried out at the Radiology Department of a University Teaching Hospital in Nigeria between June, 2011 and June 2013. Radiographs were assessed with the aid of a viewing box for artefacts which were arranged according to prior classifications by other researchers. They were subsequently grouped according to pre-arranged format into the new classification. Result: The following groups were observed: packaging (dark), procedure (greyscale), patient (greyscale), pre-processor (dark), processor (greyscale) and post-processor (greyscale). Conclusion: Classification of artefacts based on appearance and stage of introduction into film is easier to understand and remember.展开更多
Every day we experience relationships with artefacts, which describe material objects made by humans in order to reach a goal and exploit the human feature to plan ahead. Artefacts bring together cognitive evolution a...Every day we experience relationships with artefacts, which describe material objects made by humans in order to reach a goal and exploit the human feature to plan ahead. Artefacts bring together cognitive evolution and technical enhancement. Although artefacts are conceived as technical, we are now facing a relationship with Information Technology （IT） artefacts. IT artefacts include both hardware and software, as a two-sided entity. The definition of IT artefact corresponds with the Saussurean linguistic sign： a two-sided entity constituted by the signifier （hardware） and the signified （software）. I claim that IT artefacts share this ontological trait with the linguistic sign. I will show that IT artefacts are the result of design and planning, while language--which is an institution--is not the fabrication of one human but linked to collective human activity.展开更多
The safety monitoring of lithium-ion batteries(LIBs) is of great significance for realizing all-climate and full-lifespan battery management. In-situ measurement of anode potential with implanted reference electrodes(...The safety monitoring of lithium-ion batteries(LIBs) is of great significance for realizing all-climate and full-lifespan battery management. In-situ measurement of anode potential with implanted reference electrodes(REs) has proven to be effective to monitor and avoid the occurrence of severe side reactions like Li plating to ensure the safe and fast charging. However, the intrinsic measurement errors caused by local blocking effects, which also can be referred to as potential artefacts, are seldom taken into consideration in existing studies, yet they highly dominate the correctness of conclusions inferred from REs. In this study, aiming at exploring the physical origin of the measurement errors and ensure reliable potential monitoring, electrochemical and post-mortem tests are conducted using commercial pouch cells with implanted REs. Corresponding electrochemical model which describes the blocking effects, is established to validate the abnormal absence of lithium plating that predicted by measured anode potentials under various charging rates. Theoretical derivation is further presented to explain the error sources, which can be attributed to increased local liquid potential of the RE position. Most importantly, with the guidance of error analysis, a novel parameter-independent error correction method for RE measurements is proposed for the first time, which is proven to be adequate to estimate the real anode potentials and deduce the critical C-rate of Li plating with extra safety margin. After error correction, the resulting critical C-rates are all within the range of 0.55 ± 0.03 C, which is close to the C-rate of 0.6–0.7 C obtained from experiments. In addition, this error correction method can be performed conveniently with only some simple RE measurements of polarization voltages, totally independent of battery electrochemical and geometric parameters. This study provides highly practical error correction method for RE measurements in real LIBs, substantially facilitating the fast diagnosis and safe展开更多
This paper presents research aimed at identifying the methods with which prehistoric man interacted with marine and inland water environments. The objective is to determine the degree to which resources from these env...This paper presents research aimed at identifying the methods with which prehistoric man interacted with marine and inland water environments. The objective is to determine the degree to which resources from these environments influenced the socio-economic organization of these peoples. The coastline around Cagliari and its hinterland （southern Sardinia, Italy） were chosen as the subject, on the basis of the presence of both the sea and several ponds. The territory is noted as being home to both Neolithic and Eneolithic settlements. Among these the archaeological excavation of the village of Su Coddu/Canelles produced a large quantity of malacofauna. Data has been processed from part of the settlement that gave radiocarbon dating from the period between 3640 and 2900 cal. BC, and in which it was possible to carry out the level of sampling that was necessary to complete the research. In particular this interdisciplinary project, which aims to make an overall study of the settlement, the data relating to the geography of the area, the archaeological documentation, the fauna and shell artefacts will be extrapolated. Numerous methods are applied above all in reference to the marines and ponds resources. Additionally, the morphological anatomical-comparative analysis （in order to determine the typology of the faunal remains and to identify each individual species） and the technological analysis of the manufactured shells （so as to detect the selection and the transformation type of raw materials） are accomplished. The research has led to the identification of a settlement model in which agriculture formed the primary means of subsistence, that was complemented by the rearing of livestock, through hunting and gathering. The exploitation of marine and inland waters resources, as food source, have to be important because 99% of the faunal remains are shells. Different shell species are recognized, among those the Ostrea edulis provides the raw material to produce bevelled objects, which are documented inside 展开更多
This study explores the aesthetic dimensions of Kwame Nkrumah＇s cultural policies in the creation of Ghana＇s Presidential Seats and the State Sword. The study is an Art Historical research situated within the qualit...This study explores the aesthetic dimensions of Kwame Nkrumah＇s cultural policies in the creation of Ghana＇s Presidential Seats and the State Sword. The study is an Art Historical research situated within the qualitative research paradigm. It had a population of a defmed class of cultural policy makers, art historians, traditional rulers, nationalists, visual artists and Ghanaians resident both in and outside Ghana. The study examined how the creation of Ghana＇s Presidential Seats and the State Sword were influenced by Kwame Nkrumah＇s cultural policies and the cultural significance of the aesthetic interplay of ethnic insignias used in capturing the Ghanaian concept of Political authority. The study revealed that, Nkrumah recognised the cultural art forms and elements of ethnic Ghana as assets for national development. In line with his policy of building the Nation State of Ghana, he used ethnic cultural art forms and elements. At independence, Nkrumah commissioned some visual artist to create some artistic pieces （politico-cultural artefacts） for the Ghanaian political authority with inspiration or based on what pertains in the traditional authority （Chieftaincy） of Ghana. Politico-cultural artefacts as used in this study refer to the artefacts produced based on the cultural concepts of the ethnic states for the use of the political authority of the Republic of Ghana. Among these artistic pieces are the three Presidential Seats, The State Sword, The President＇s Personal Standard Pole and the State Mace.展开更多
Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as"unperturbed", we found that ne...Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as"unperturbed", we found that neither could accurately measure the size of NPs featuring a broad size distribution, e.g., aggregates. Because many real-world NP samples consist of aggregates, this finding was of considerable concern. The data showed that the protocols introduced errors into the measurement by either inducing agglomeration artefacts or providing a skewed size distribution towards small particles (skewing artefact). The focus of this work was to develop and apply a mathematical refinement to correct the skewing artefact. This refinement provided a much improved agreement between EM and a reference methodology, when applied to the measurement of synthetic amorphous silica NPs. Further investigation, highlighted the influence of NP chemistry on the refinement. This study emphasised the urgent need for greater and more detailed consideration regarding the sample preparation of NP aggregates to routinely achieve accurate measurements by EM. This study also provided a novel refinement solution applicable to the size characterisation of silica and c让rate-coated gold NPs featuring broad size distributions. With further research, this approach could be extended to other NP types.展开更多
文摘Cone beam computed tomography (CBCT) is the modern third dimension applied in the field of oral maxillofacial region. With lower radiation dose compared to conventional CT, its applications in dentistry has increased tremendously. Artefacts can seriously degrade the quality of computed tomographic (CBCT) images, sometimes to the point of making them diagnostically unusable. To optimize image quality, it is necessary to understand why artifacts occur and how they can be prevented or suppressed. CT artifacts originate from a range of sources;physical based, scanner based and patient based. This article highlights the causes of artefacts on CBCT images and methods to avoid them.
文摘 AIM: To evaluate the value of administration of hyoscine-N-butyl-bromide (HBB) for image quality magnetic resonance imaging (MRI) of the prostate. METHODS: Seventy patients were retrospectively included in the study. Thirty-five patients were examined with administration of 40 milligrams of HBB (Buscopan ; Boehringer, Ingelheim, Germany); 35 patients were examined without HBB. A multiparametric MRI protocol was performed on a 3.0 Tesla scanner without using an endorectal coil. The following criteria were evaluated independently by two experienced radiologists on a five-point Likert scale: anatomical details (delineation between peripheral and transitional zone of the prostate, visualisation of the capsule, depiction of the neurovascular bundles); visualisation of lymph nodes; motion related artefacts; and overall image quality.RESULTS: Comparison of anatomical details between the two cohorts showed no statistically significant difference (3.9 ± 0.7 vs 4.0 ± 0.9, P = 0.54, and 3.8 ± 0.7 vs 4.2 ± 0.6, P = 0.07) for both readers. There was no significant advantage regarding depiction of local and iliac lymph nodes (3.9 ± 0.6 vs 4.2 ± 0.6, P = 0.07, and 3.8 ± 0.9 vs 4.1 ± 0.8, P = 0.19). Motion arte- facts were rated as 'none' to 'few' in both groups and showed no statistical difference (2.3 ± 1.0 vs 1.9 ± 0.9, P = 0.19, and 2.3 ± 1.1 vs 1.9 ± 0.7, P = 0.22). Overall image quality was rated 'good' in average for both cohorts without significant difference (4.0 ± 0.6 vs 4.0 ± 0.9, P = 0.78, and 3.8 ± 0.8 vs 4.2 ± 0.6, P = 0.09). CONCLUSION: The results demonstrated no significant effect of HBB administration on image quality. The study suggests that use of HBB is not mandatory for MRI of the prostate at 3.0 Tesla.
基金supported by the National Natural Science Foundation of China (Grant Nos. U1532113, 11475170, and 11905041)the Fundamental Research Funds for the Central Universities (Grant No. PA2020GDKC0024)Anhui Provincial Natural Science Foundation, China (Grant No. 2208085MA18)。
文摘X-ray analyzer-based imaging(ABI) is a powerful phase-sensitive technique that can provide a wide dynamic range of density and extract useful physical properties of the sample. It derives contrast from x-ray absorption, refraction, and scattering properties of the investigated sample. However, x-ray ABI setups can be susceptible to external vibrations, and mechanical imprecisions of system components, e.g., the precision of motor, which are unavoidable in practical experiments. Those factors will provoke deviations of analyzer angular positions and hence errors in the acquired image data.Consequently, those errors will introduce artefacts in the retrieved refraction and scattering images. These artefacts are disadvantageous for further image interpretation and tomographic reconstruction. For this purpose, this work aims to analyze image artefacts resulting from deviations of analyzer angular positions. Analytical expressions of the refraction and scattering image artefacts are derived theoretically and validated by synchrotron radiation experiments. The results show that for the refraction image, the artefact is independent of the sample’s absorption and scattering signals. By contrast, artefact of the scattering image is dependent on both the sample’s refraction and scattering signals, but not on absorption signal.Furthermore, the effect of deviations of analyzer angular positions on the accuracy of the retrieved images is investigated,which can be of use for optimization of data acquisition. This work offers the possibility to develop advanced multi-contrast image retrieval algorithms that suppress artefacts in the retrieved refraction and scattering images in x-ray analyzer-based imaging.
文摘Objective: To propose a new method of classifying film-screen radiographic artefacts. Methodology: A prospective study was carried out at the Radiology Department of a University Teaching Hospital in Nigeria between June, 2011 and June 2013. Radiographs were assessed with the aid of a viewing box for artefacts which were arranged according to prior classifications by other researchers. They were subsequently grouped according to pre-arranged format into the new classification. Result: The following groups were observed: packaging (dark), procedure (greyscale), patient (greyscale), pre-processor (dark), processor (greyscale) and post-processor (greyscale). Conclusion: Classification of artefacts based on appearance and stage of introduction into film is easier to understand and remember.
文摘Every day we experience relationships with artefacts, which describe material objects made by humans in order to reach a goal and exploit the human feature to plan ahead. Artefacts bring together cognitive evolution and technical enhancement. Although artefacts are conceived as technical, we are now facing a relationship with Information Technology （IT） artefacts. IT artefacts include both hardware and software, as a two-sided entity. The definition of IT artefact corresponds with the Saussurean linguistic sign： a two-sided entity constituted by the signifier （hardware） and the signified （software）. I claim that IT artefacts share this ontological trait with the linguistic sign. I will show that IT artefacts are the result of design and planning, while language--which is an institution--is not the fabrication of one human but linked to collective human activity.
基金supported by the Ministry of Science and Technology of China(2019YFE0100200)funded by the National Natural Science Foundation of China(51807108,51877121,52037006)。
文摘The safety monitoring of lithium-ion batteries(LIBs) is of great significance for realizing all-climate and full-lifespan battery management. In-situ measurement of anode potential with implanted reference electrodes(REs) has proven to be effective to monitor and avoid the occurrence of severe side reactions like Li plating to ensure the safe and fast charging. However, the intrinsic measurement errors caused by local blocking effects, which also can be referred to as potential artefacts, are seldom taken into consideration in existing studies, yet they highly dominate the correctness of conclusions inferred from REs. In this study, aiming at exploring the physical origin of the measurement errors and ensure reliable potential monitoring, electrochemical and post-mortem tests are conducted using commercial pouch cells with implanted REs. Corresponding electrochemical model which describes the blocking effects, is established to validate the abnormal absence of lithium plating that predicted by measured anode potentials under various charging rates. Theoretical derivation is further presented to explain the error sources, which can be attributed to increased local liquid potential of the RE position. Most importantly, with the guidance of error analysis, a novel parameter-independent error correction method for RE measurements is proposed for the first time, which is proven to be adequate to estimate the real anode potentials and deduce the critical C-rate of Li plating with extra safety margin. After error correction, the resulting critical C-rates are all within the range of 0.55 ± 0.03 C, which is close to the C-rate of 0.6–0.7 C obtained from experiments. In addition, this error correction method can be performed conveniently with only some simple RE measurements of polarization voltages, totally independent of battery electrochemical and geometric parameters. This study provides highly practical error correction method for RE measurements in real LIBs, substantially facilitating the fast diagnosis and safe
文摘This paper presents research aimed at identifying the methods with which prehistoric man interacted with marine and inland water environments. The objective is to determine the degree to which resources from these environments influenced the socio-economic organization of these peoples. The coastline around Cagliari and its hinterland （southern Sardinia, Italy） were chosen as the subject, on the basis of the presence of both the sea and several ponds. The territory is noted as being home to both Neolithic and Eneolithic settlements. Among these the archaeological excavation of the village of Su Coddu/Canelles produced a large quantity of malacofauna. Data has been processed from part of the settlement that gave radiocarbon dating from the period between 3640 and 2900 cal. BC, and in which it was possible to carry out the level of sampling that was necessary to complete the research. In particular this interdisciplinary project, which aims to make an overall study of the settlement, the data relating to the geography of the area, the archaeological documentation, the fauna and shell artefacts will be extrapolated. Numerous methods are applied above all in reference to the marines and ponds resources. Additionally, the morphological anatomical-comparative analysis （in order to determine the typology of the faunal remains and to identify each individual species） and the technological analysis of the manufactured shells （so as to detect the selection and the transformation type of raw materials） are accomplished. The research has led to the identification of a settlement model in which agriculture formed the primary means of subsistence, that was complemented by the rearing of livestock, through hunting and gathering. The exploitation of marine and inland waters resources, as food source, have to be important because 99% of the faunal remains are shells. Different shell species are recognized, among those the Ostrea edulis provides the raw material to produce bevelled objects, which are documented inside
文摘This study explores the aesthetic dimensions of Kwame Nkrumah＇s cultural policies in the creation of Ghana＇s Presidential Seats and the State Sword. The study is an Art Historical research situated within the qualitative research paradigm. It had a population of a defmed class of cultural policy makers, art historians, traditional rulers, nationalists, visual artists and Ghanaians resident both in and outside Ghana. The study examined how the creation of Ghana＇s Presidential Seats and the State Sword were influenced by Kwame Nkrumah＇s cultural policies and the cultural significance of the aesthetic interplay of ethnic insignias used in capturing the Ghanaian concept of Political authority. The study revealed that, Nkrumah recognised the cultural art forms and elements of ethnic Ghana as assets for national development. In line with his policy of building the Nation State of Ghana, he used ethnic cultural art forms and elements. At independence, Nkrumah commissioned some visual artist to create some artistic pieces （politico-cultural artefacts） for the Ghanaian political authority with inspiration or based on what pertains in the traditional authority （Chieftaincy） of Ghana. Politico-cultural artefacts as used in this study refer to the artefacts produced based on the cultural concepts of the ethnic states for the use of the political authority of the Republic of Ghana. Among these artistic pieces are the three Presidential Seats, The State Sword, The President＇s Personal Standard Pole and the State Mace.
文摘Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as"unperturbed", we found that neither could accurately measure the size of NPs featuring a broad size distribution, e.g., aggregates. Because many real-world NP samples consist of aggregates, this finding was of considerable concern. The data showed that the protocols introduced errors into the measurement by either inducing agglomeration artefacts or providing a skewed size distribution towards small particles (skewing artefact). The focus of this work was to develop and apply a mathematical refinement to correct the skewing artefact. This refinement provided a much improved agreement between EM and a reference methodology, when applied to the measurement of synthetic amorphous silica NPs. Further investigation, highlighted the influence of NP chemistry on the refinement. This study emphasised the urgent need for greater and more detailed consideration regarding the sample preparation of NP aggregates to routinely achieve accurate measurements by EM. This study also provided a novel refinement solution applicable to the size characterisation of silica and c让rate-coated gold NPs featuring broad size distributions. With further research, this approach could be extended to other NP types.
