Early ship-based upper-air data and comparison with the Twentieth Century

Extension of 3-D atmospheric data products back into the past is desirable for a wide range of applications. Historical upper-air data are important in this endeavour, particularly in the maritime regions of the tropics and the southern hemisphere, where observations are extremely sparse. Here we present newly digitized and re-evaluated early ship-based upper-air data from two cruises: (1) kite and registering balloon profiles from onboard the ship SMS Planet on a cruise from Europe around South Africa and across the Indian Ocean to the western Pacific in 1906/1907, and (2) ship-based radiosonde data from onboard the MS Schwabenland on a cruise from Europe across the Atlantic to Antarctica and back in 1938/1939. We describe the data and provide estimations of the errors. We compare the data with a recent reanalysis (the Twentieth Century Reanalysis Project, 20CR, Compo et al., 2011) that provides global 3-D data back to the 19th century based on an assimilation of surface pressure data only (plus monthly mean sea-surface temperatures). In cruise (1), the agreement is generally good, but large temperature differences appear during a period with a strong inversion. In cruise (2), after a subset of the data are corrected, close agreement between observations and 20CR is found for geopotential height (GPH) and temperature notwithstanding a likely cold bias of 20CR at the tropopause level. Results are considerably worse for relative humidity, which was reportedly inaccurately measured. Note that comparing 20CR, which has limited skill in the tropical regions, with measurements from ships in remote regions made under sometimes difficult conditions can be considered a worst case assessment. In view of that fact, the anomaly correlations for temperature of 0.3–0.6 in the lower troposphere in cruise (1) and of 0.5–0.7 for tropospheric temperature and GPH in cruise (2) are considered as promising results. Moreover, they are consistent with the error estimations. The results suggest room for further improvement of data products in remote regions.

Assessment of smoking behaviour in the dental setting. A study comparing self-reported questionnaire data and exhaled carbon monoxide levels

The present study validated the accuracy of data from a self-reported questionnaire on smoking behaviour with the use of exhaled carbon monoxide (CO) level measurements in two groups of patients. Group 1 included patients referred to an oral medicine unit, whereas group 2 was recruited from the daily outpatient service. All patients filled in a standardized questionnaire regarding their current and former smoking habits. Additionally, exhaled CO levels were measured using a monitor. A total of 121 patients were included in group 1, and 116 patients were included in group 2. The mean value of exhaled CO was 7.6 ppm in the first group and 9.2 ppm in the second group. The mean CO values did not statistically significantly differ between the two groups. The two exhaled CO level measurements taken for each patient exhibited very good correlation (Spearman's coefficient of 0.9857). Smokers had a mean difference of exhaled CO values of 13.95 ppm (p < 0.001) compared to non-smokers adjusted for the first or second group. The consumption of one additional pack year resulted in an increase in CO values of 0.16 ppm (p = 0.003). The consumption of one additional cigarette per day elevated the CO measurements by 0.88 ppm (p < 0.001). Based on these results, the correlations between the self-reported smoking habits and exhaled CO values are robust and highly reproducible. CO monitors may offer a non-invasive method to objectively assess current smoking behaviour and to monitor tobacco use cessation attempts in the dental setting.

Insights into the timing of repeated testing after treatment for Chlamydia trachomatis: data and modelling study

The objective of this study was to determine the optimal time interval for a repeated Chlamydia trachomatis (chlamydia) test.

Accurate and robust reconstruction of proximal femur from sparse intraoperative data and dense point distribution model for surgical navigation

Constructing a 3D surface model from sparse-point data is a nontrivial task. Here, we report an accurate and robust approach for reconstructing a surface model of the proximal femur from sparse-point data and a dense-point distribution model (DPDM). The problem is formulated as a three-stage optimal estimation process. The first stage, affine registration, is to iteratively estimate a scale and a rigid transformation between the mean surface model of the DPDM and the sparse input points. The estimation results of the first stage are used to establish point correspondences for the second stage, statistical instantiation, which stably instantiates a surface model from the DPDM using a statistical approach. This surface model is then fed to the third stage, kernel-based deformation, which further refines the surface model. Handling outliers is achieved by consistently employing the least trimmed squares (LTS) approach with a roughly estimated outlier rate in all three stages. If an optimal value of the outlier rate is preferred, we propose a hypothesis testing procedure to automatically estimate it. We present here our validations using four experiments, which include 1 leave-one-out experiment, 2 experiment on evaluating the present approach for handling pathology, 3 experiment on evaluating the present approach for handling outliers, and 4 experiment on reconstructing surface models of seven dry cadaver femurs using clinically relevant data without noise and with noise added. Our validation results demonstrate the robust performance of the present approach in handling outliers, pathology, and noise. An average 95-percentile error of 1.7-2.3 mm was found when the present approach was used to reconstruct surface models of the cadaver femurs from sparse-point data with noise added.

Hardware accelerated ray cast of volume data and volume gradient for an optimized splines-based multi-resolution 2D-3D registration

This paper describes a method for DRR generation as well as for volume gradients projection using hardware accelerated 2D texture mapping and accumulation buffering and demonstrates its application in 2D-3D registration of X-ray fluoroscopy to CT images. The robustness of the present registration scheme are guaranteed by taking advantage of a coarse-to-fine processing of the volume/image pyramids based on cubic B-splines. A human cadaveric spine specimen together with its ground truth was used to compare the present scheme with a purely software-based scheme in three aspects: accuracy, speed, and capture ranges. Our experiments revealed an equivalent accuracy and capture ranges but with much shorter registration time with the present scheme. More specifically, the results showed 0.8 mm average target registration error, 55 second average execution time per registration, and 10 mm and 10° capture ranges for the present scheme when tested on a 3.0 GHz Pentium 4 computer.