Dai Gia - Academia.edu (original) (raw)
Papers by Dai Gia
Journal of Equine Veterinary Science, 2008
A 12-day-old, 14.4-kg, female foal of Australian Miniature Pony breed was presented at the Nation... more A 12-day-old, 14.4-kg, female foal of Australian Miniature Pony breed was presented at the National Chung Hsing University Veterinary Medicine Teaching Hospital, Taiwan, with a history of weakness of 2 days' duration. The mare died of unknown cause on the previous day. Abnormal findings during physical examination included an estimated dehydration of 3 to 5%, dark red oral mucous membranes, elevated heart and respiratory rates, stiffened feces, and absence of intestinal motility on auscultation. Continual nursing care was followed by intravenous fluid therapy and nonsteroidal anti-inflammatory drug and antibiotic treatment. The foal's condition deteriorated rapidly, and feeding was refused. Subsequently, she developed signs of pyrexia and panting. In spite of oxygen supplement, she died 18 hours after admission. Postmortem examination revealed the presence of a jejunojejunal intussusception, 20 cm in length; a torsion of jejunum proximal to the intussusception also was noted. An ulcerative lesion, 3 cm in diameter, was found on the mucosa of duodenum. Large amounts of sand, coat hair, and hay mantling in bloody discharge were observed in a colonic impaction. That it was an acute case was evident by the involvement of intussusception and ulceration, indicating desquamation of the necrotic epithelial cells with edema and distinct infiltration of neutrophils. These results suggested that a practical management strategy for nursing an orphan foal should be performed to avoid a similar case in the future.
Generating numerical predictions of glacial isostatic adjustment (GIA) in North America is compli... more Generating numerical predictions of glacial isostatic adjustment (GIA) in North America is complicated by difficulties associated with constraining the full history of the ice sheet, as well as the 3D variations of mantle viscosity and lithospheric structure, with limited sets of observations. Moreover, many GIA predictions are calculated with spherically-symmetric Earth models, which may fail to capture the full range of possible crustal motions. However, most geodetic applications only require accurate estimates of the present-day variations in crustal displacement and gravity associated with GIA. Thus, Davis et al., 2006, developed a data assimilation technique to obtain a present-day estimate of GIA. The technique combines GPS and GRACE observations with the covariance of these signals derived from a set of forward model predictions. This approach has the advantage of allowing the data to improve the GIA estimate without having to associate these results with changes in input ice-sheet history and viscosity structure, which may be inadequate due to model limitations to describe the actual motions. To examine the robustness of the solutions resulting from this technique, we investigate the impact of the starting model used in the determination of the model covariances. In addition, we explore sampling issues and the ability to recover motions caused by lateral Earth structure by using input from a 3D numerical Earth model prediction sampled in the same manner as the GPS and GRACE inputs.
We present a statistical approach for estimating three-dimensional crustal deformation using data... more We present a statistical approach for estimating three-dimensional crustal deformation using data assimilation. Numerical predictions of GIA are sensitive to errors in the adopted Earth and ice models. To constrain those models, researchers have used a variety of data types, including historical and present-day sea-level change and the long-wavelength geoid. Geodetic data have also been used to investigate the GIA process and to refine the Earth model. The model-constraint approach has proven useful, but its applicability is limited due to the nature of the problem. The ice-history model, for example, is difficult to parametrize and constrain uniquely. The assumption of spherical symmetry is particularly suspect, and the newer Earth models that incorporate lateral variations increase the complexity of the problem significantly. For certain applications, however, the main goal is to obtain an improved set of predictions for the present-day GIA deformation. This goal is particularly relevant when we wish to remove the GIA effects to "correct" other observations of crustal deformation or sea-level. Such applications require an accurate model for GIA deformation and gravity change, but they do not require that the Earth and ice models be known. We describe an approach to solving this class of problems that uses a Kalman filter to assimilate simultaneously GPS and GRACE observations of crustal motion into the a priori GIA models. Assimilation techniques are in common use for problems in which the predictions of numerical forward models are constrained by a set of observations and/or adopted values for model parameters. When additional observational constraints are added a new forward model is generated without necessarily determining corrections to model parameters. We will examine the sensitivity and biases of this technique, and compare results to sea-level rates obtained from North American and Fennoscandian tide gauges.
NXB Đại học quốc gia Hà Nội 2006, 565 Tr. Từ khoá: Mặt phẳng phức, Hàm số phức, số phức, Hàm biến... more NXB Đại học quốc gia Hà Nội 2006, 565 Tr. Từ khoá: Mặt phẳng phức, Hàm số phức, số phức, Hàm biến phức, Điểm tụ, Biên của tập hợp, Tập hợp compact, Hàm phức biến thực, Miền đơn liên, Đa liên, Hàm chỉnh hình, Ánh xạ bảo giác, Ánh xạ chỉnh hình, Nguyên lý thác triển giải tích, tập hợp mờ, Hàm đa trị, Diện đa liên, Lý thuyết thặng dư, Hàm đơn diệp, Phiến hàm liên tục, Diện Riemann. Tài liệu trong Thư viện điện tử ĐH Khoa học Tự nhiên có thể sử dụng cho mục đích học tập và nghiên cứu cá nhân. Nghiêm cấm mọi hình thức sao chép, in ấn phục vụ các mục đích khác nếu không được sự chấp thuận của nhà xuất bản và tác giả.
Journal of Equine Veterinary Science, 2008
A 12-day-old, 14.4-kg, female foal of Australian Miniature Pony breed was presented at the Nation... more A 12-day-old, 14.4-kg, female foal of Australian Miniature Pony breed was presented at the National Chung Hsing University Veterinary Medicine Teaching Hospital, Taiwan, with a history of weakness of 2 days' duration. The mare died of unknown cause on the previous day. Abnormal findings during physical examination included an estimated dehydration of 3 to 5%, dark red oral mucous membranes, elevated heart and respiratory rates, stiffened feces, and absence of intestinal motility on auscultation. Continual nursing care was followed by intravenous fluid therapy and nonsteroidal anti-inflammatory drug and antibiotic treatment. The foal's condition deteriorated rapidly, and feeding was refused. Subsequently, she developed signs of pyrexia and panting. In spite of oxygen supplement, she died 18 hours after admission. Postmortem examination revealed the presence of a jejunojejunal intussusception, 20 cm in length; a torsion of jejunum proximal to the intussusception also was noted. An ulcerative lesion, 3 cm in diameter, was found on the mucosa of duodenum. Large amounts of sand, coat hair, and hay mantling in bloody discharge were observed in a colonic impaction. That it was an acute case was evident by the involvement of intussusception and ulceration, indicating desquamation of the necrotic epithelial cells with edema and distinct infiltration of neutrophils. These results suggested that a practical management strategy for nursing an orphan foal should be performed to avoid a similar case in the future.
Generating numerical predictions of glacial isostatic adjustment (GIA) in North America is compli... more Generating numerical predictions of glacial isostatic adjustment (GIA) in North America is complicated by difficulties associated with constraining the full history of the ice sheet, as well as the 3D variations of mantle viscosity and lithospheric structure, with limited sets of observations. Moreover, many GIA predictions are calculated with spherically-symmetric Earth models, which may fail to capture the full range of possible crustal motions. However, most geodetic applications only require accurate estimates of the present-day variations in crustal displacement and gravity associated with GIA. Thus, Davis et al., 2006, developed a data assimilation technique to obtain a present-day estimate of GIA. The technique combines GPS and GRACE observations with the covariance of these signals derived from a set of forward model predictions. This approach has the advantage of allowing the data to improve the GIA estimate without having to associate these results with changes in input ice-sheet history and viscosity structure, which may be inadequate due to model limitations to describe the actual motions. To examine the robustness of the solutions resulting from this technique, we investigate the impact of the starting model used in the determination of the model covariances. In addition, we explore sampling issues and the ability to recover motions caused by lateral Earth structure by using input from a 3D numerical Earth model prediction sampled in the same manner as the GPS and GRACE inputs.
We present a statistical approach for estimating three-dimensional crustal deformation using data... more We present a statistical approach for estimating three-dimensional crustal deformation using data assimilation. Numerical predictions of GIA are sensitive to errors in the adopted Earth and ice models. To constrain those models, researchers have used a variety of data types, including historical and present-day sea-level change and the long-wavelength geoid. Geodetic data have also been used to investigate the GIA process and to refine the Earth model. The model-constraint approach has proven useful, but its applicability is limited due to the nature of the problem. The ice-history model, for example, is difficult to parametrize and constrain uniquely. The assumption of spherical symmetry is particularly suspect, and the newer Earth models that incorporate lateral variations increase the complexity of the problem significantly. For certain applications, however, the main goal is to obtain an improved set of predictions for the present-day GIA deformation. This goal is particularly relevant when we wish to remove the GIA effects to "correct" other observations of crustal deformation or sea-level. Such applications require an accurate model for GIA deformation and gravity change, but they do not require that the Earth and ice models be known. We describe an approach to solving this class of problems that uses a Kalman filter to assimilate simultaneously GPS and GRACE observations of crustal motion into the a priori GIA models. Assimilation techniques are in common use for problems in which the predictions of numerical forward models are constrained by a set of observations and/or adopted values for model parameters. When additional observational constraints are added a new forward model is generated without necessarily determining corrections to model parameters. We will examine the sensitivity and biases of this technique, and compare results to sea-level rates obtained from North American and Fennoscandian tide gauges.
NXB Đại học quốc gia Hà Nội 2006, 565 Tr. Từ khoá: Mặt phẳng phức, Hàm số phức, số phức, Hàm biến... more NXB Đại học quốc gia Hà Nội 2006, 565 Tr. Từ khoá: Mặt phẳng phức, Hàm số phức, số phức, Hàm biến phức, Điểm tụ, Biên của tập hợp, Tập hợp compact, Hàm phức biến thực, Miền đơn liên, Đa liên, Hàm chỉnh hình, Ánh xạ bảo giác, Ánh xạ chỉnh hình, Nguyên lý thác triển giải tích, tập hợp mờ, Hàm đa trị, Diện đa liên, Lý thuyết thặng dư, Hàm đơn diệp, Phiến hàm liên tục, Diện Riemann. Tài liệu trong Thư viện điện tử ĐH Khoa học Tự nhiên có thể sử dụng cho mục đích học tập và nghiên cứu cá nhân. Nghiêm cấm mọi hình thức sao chép, in ấn phục vụ các mục đích khác nếu không được sự chấp thuận của nhà xuất bản và tác giả.