Accurate Calibration of a Large Field of View Camera with Coplanar Constraint for Large-Scale Specular Three-Dimensional Profile Measurement.

In the vision-based inspection of specular or shiny surfaces, we often compute the camera pose with respect to a reference plane by analyzing images of calibration grids, reflected in such a surface. To obtain high precision in camera calibration, the calibration target should be large enough to cover the whole field of view (FOV). For a camera with a large FOV, using a small target can only obtain a locally optimal solution. However, using a large target causes many difficulties in making, carrying, and employing the large target. To solve this problem, an improved calibration method based on coplanar constraint is proposed for a camera with a large FOV. Firstly, with an auxiliary plane mirror provided, the positions of the calibration grid and the tilt angles of the plane mirror are changed several times to capture several mirrored calibration images. Secondly, the initial parameters of the camera are calculated based on each group of mirrored calibration images. Finally, adding with the coplanar constraint between each group of calibration grid, the external parameters between the camera and the reference plane are optimized via the Levenberg-Marquardt algorithm (LM). The experimental results show that the proposed camera calibration method has good robustness and accuracy.

Initial Clinical Characteristics of 146 Patients with COVID-19 Reported in Guizhou Province, China: A Survival Analysis.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) has caused an outbreak around the world. Early detection of severe illness is crucial for patients' survival. We analysed initial clinical characteristics of 146 patients with COVID-19 reported in Guizhou province, China to explore risk factors for transforming mild illness to severe. METHODOLOGY: Data of 146 laboratory-confirmed cases were collected and evaluated by the survival analysis of univariate and multivariate Cox proportional hazards model. RESULTS: On initial presentation, patients had fever (51.05%), dry cough (45.45%), headache (16.08%), shortness of breath (7.75%) and gastrointestinal symptoms (13.99%). Among 146 laboratory-confirmed cases, 30 patients (20.55%) had severe illness and needed Intensive Care Unit care for supportive treatment. The remaining patients (116, 79.45%) were non-severe cases. Nineteen (19/146, 13.01%) of 30 patients in the Intensive Care Unit had comorbidities, including hypertension (12, 40.00%), diabetes (5, 16.67%), cardiovascular disease (5, 16.67%) and pulmonary disease (4, 13.33%). For survival analysis, patients who had fever (HR = 3.30, 95% CI = 1.31, 8.29) and comorbidities (HR = 9.76, 95% CI = 4.28, 22.23) at baseline were more likely to be admitted into the Intensive Care Unit. Few variables were not related to the survival time of discharge from baseline to discharge and from Intensive Care Unit care to discharge. CONCLUSIONS: Severe patients with COVID-19 should be paid more attention. On initial symptoms, many patients did not have fever, but those with fever were more likely to be admitted to the Intensive Care Unit. Comorbidities were likewise a risk factor of severe COVID-19.

Epidemiologic Characteristics of COVID-19 in Guizhou Province, China.

INTRODUCTION: At the end of 2019, the COVID-19 broke out, and spread to Guizhou province in January of 2020. METHODOLOGY: To acquire the epidemiologic characteristics of COVID-19 in Guizhou province, we collected data from 169 laboratory-confirmed COVID-19 related cases. We described the demographic characteristics of the cases and estimated the incubation period, serial interval and the effective reproduction number. We also presented two representative case studies in Guizhou province: Case Study 1 was an example of the asymptomatic carrier; while Case Study 2 was an example of a large and complex infection chain that involved four different regions, spanning three provinces and eight families. RESULTS: Two peaks in the incidence distribution associated with COVID-19 in Guizhou province were related to the 6.04 days (95% CI: 5.00 - 7.10) of incubation period and 6.14±2.21 days of serial interval. We also discussed the effectiveness of the control measures based on the instantaneous effective reproduction number that was a constantly declining curve. CONCLUSIONS: As of February 2, 2020, the estimated effective reproduction number was below 1, and no new cases were reported since February 26. These showed that Guizhou Province had achieved significant progress in preventing the spread of the epidemic. The medical isolation of close contacts was consequential. Meanwhile, the asymptomatic carriers and the super-spreaders must be isolated in time, who would cause a widespread infection.

[Investigation on the causes of increased hepatitis E cases reported in Guizhou province].

OBJECTIVE: To analyze causes of growing hepatitis E (HE) cases reported in Guizhou province, and probe into existing problems faced by medical institutions in diagnosis of clinical and laboratory-confirmed cases, for the purpose of improving the quality of HE surveillance system. METHODS: Six hospitals reporting greater HE cases from 2007 to 2011 were pinpointed, whose reported cases rose suddenly in 2011. Such cases were investigated by means of impatient medical record review, results of laboratory test and clinician interview. RESULTS: 136 of the 354 reported HE cases investigated were found compliant with the diagnostic criteria of HE with an accordance rate of 38.42%. Difference of the HE diagnostic accordance rate among individual years, hospitals and reporting departments was statistically significant. Such rate of hospital reports was found to be the lowest in 2011, ranging from 0 to 18.18% respectively; HE cases reported by non-infectious departments accounted for 61.30% of total cases reported, with its accordance rate considerably below the infectious departments (8.29%). HE positive cases and HE positive rate in 2011 were significantly higher than that of preceding years. CONCLUSION: Such increase of reported HE cases in 2011 in the province was mostly attributable to more HE laboratory tests made by the hospitals, yet the accordance rates were lower than satisfactory. In this regard, the medical institutions in question were advised to enhance their competency training for HE diagnosis and case report quality.

[Evaluation on the effects of prevention and control programs regarding typhoid fever and paratyphoid fever in Guizhou province, from 2007 to 2012].

OBJECTIVE: This study was to evaluate the effects of prevention and control regarding programs on typhoid fever and paratyphoid fever, in Guizhou province, from 2007 to 2012, to provide evidence for the improvement of related programs. METHODS: Data on typhoid fever and paratyphoid including information on epidemics, individual, cases, measures for prevention and control programs taken and relative government documents were collected and analyzed in Guizhou province, from 2007 to 2012. Information related to the average annual incidence, nature of outbreaks, time span before confirmed diagnosis was made, unit which carried the case report, proportion of laboratory confirmed diagnosed cases and case-management were compared between 2007-2009 and 2010-2012 descriptively while chi-square test with Excel and EpiInfo software were used for data analysis. RESULTS: In the period of 2007-2009, a total of 5 978 typhoid fever and paratyphoid fever cases were reported in Guizhou province with the average yearly incidence as 5.29/100 000. In the period of 2010-2012, 2 765 cases were reported with the average yearly incidence as 2.57/100 000. When compared to the former, data from the latter period showed that the average yearly incidence had declined 51.31% in all the prefectures. There were still some outbreaks appeared but the total number of cases involved reduced 87.50%. The time span before the confirmation of diagnosis became shorter but the difference was not statistically significant (χ² = 0.08, P = 0.99). Number of cases reported by hospitals at county or above had 11.51% of increase while those cases reported at the township hospitals or below decreased for 61.47% . The proportion of laboratory diagnosed cases increased 23.63%. Rates of timeliness on cards being filled in, input and audited showed increase of 8.44%, 6.76% and 2.40% respectively. CONCLUSION: Successful measures for prevention and control on typhoid fever and paratyphoid fever had been remarkably taken in Guizhou province, but the potential risk of outbreaks still existed in some areas, suggesting that health education and surveillance programs including laboratory diagnosis, should be strengthened.

[Study on the epidemiologic characteristic of Brucella melitensis isolated in Guizhou province in 2010-2012].

OBJECTIVE: To understand the genetic and epidemiologic characteristic of Brucella (B.) melitensis strains isolated in Guizhou province in 2010-2012. METHODS: B. genus specific BCSP31-PCR and species-specific AMOS-PCR were used to identify the bacteria strain, while the identified strains were analyzed under MLVA-16 and cluster analysis of B. melitensis strains. The strains were isolated from Guizhou and other provinces. RESULTS: Six B. melitensis strains were identified as B. melitensis using the BCSP31-PCR and AMOS-PCR. Data from the MLVA-16 analysis revealed the differences of repeated numbers at parts of the VNTR locus in the six strains isolated in Guizhou province. The six strains from Guizhou province and 105 B. melitensis strains from other province could be divided into 72 MLVA types(MT). Strain ZY and ZA from Guizhou province were typed as MT63, and LL3, LL4 and LL11 were typed as MT67, while strain SQ was typed as MT72. Data from the clustering analysis showed that ZY,ZA, LL3, LL4 and LL9 were most closely clustered with B. melitensis isolates from Yunnan, Fujian and Guangdong provinces, but strain SQ was genetically remote from other strains. CONCLUSION: PCR methods, combined with MLVA-16, identified the six B. melitensis strains isolated in Guizhou province in 2010-2012 as B. melitensis biovar 3, with the genetic diversity of the strains showed. Six strains were closely related to the B. melitensis strains from Yunnan, Fujian and Guangdong provinces. The results of this study provided scientific basis for the control and prevention of Brucellosis in Guizhou province.