Eleven recently completed toxicological studies were critically reviewed to identify toxicologically significant endpoints and dose-response information. Dose-response data were compiled and entered into the USEPA＇s ...Eleven recently completed toxicological studies were critically reviewed to identify toxicologically significant endpoints and dose-response information. Dose-response data were compiled and entered into the USEPA＇s benchmark dose software （BMDS） for calculation of a benchmark dose （BMD） and a benchmark dose low （BMDL）. After assessing 91 endpoints across the nine studies, a total of 23 of these endpoints were identified for BMD modeling, and BMDL estimates corresponding to various dose-response models were compiled for these separate endpoints. Thyroid, neurobehavior and reproductive endpoints for BDE-47, -99, -209 were quantitatively evaluated. According to methods and feature of each study, different uncertainty factor （UF） value was decided and subsequently reference doses （RfDs） were proposed. Consistent with USEPA, the lowest BMDLs of 2.10, 81.77, and 1698 I^g/kg were used to develop RfDs for BDE-47, -99, and -209, respectively. RfDs for BDE-99 and BDE-209 were comparable to EPA results, and however, RfD of BDE-47 was much lower than that of EPA, which may result from that reproductive/developmental proves to be more sensitive than neurobehavior for BDE-47 and the principal study uses very-low-dose exposure.展开更多
In this paper, the authors develop the earlier work of Chen Jiabin et al. (1986). In order to reduce spectral truncation errors, the reference atmosphere has been introduced in ECMWF model, and the spectrally-represen...In this paper, the authors develop the earlier work of Chen Jiabin et al. (1986). In order to reduce spectral truncation errors, the reference atmosphere has been introduced in ECMWF model, and the spectrally-represented variables, temperature, geopotential height and orography, are replaced by their deviations from the reference atmosphere. Two modified semi- implicit schemes have been proposed to alleviate the computational instability due to the introduction of reference atmosphere. Concerning the deviation of surface geopotential height from reference atmosphere, an exact computational formulation has been used instead of the approximate one in the earlier work. To re duce aliasing errors in the computations of the deviation of the surface geopotential height, a spectral fit has been used slightly to modify the original Gaussian grid-point values of orography.A series of experiments has been performed in order to assess the impact of the reference atmosphere on ECMWF medium- range forecasts at the resolution T21, T42 and T63. The results we have obtained reveal that the reference atmosphere introduced in ECMWF spectral model is generally beneficial to the mean statistical scores of 1000-200 hPa height 10-day forecasts over the globe. In the Southern Hemisphere, it is a clear improvement for T21, T42 and T63 throughout the 10-day forecast period. In the Northern Hemisphere, the impact of the reference atmos phere on anomaly correlation is positive for resolution T21, a very slightly damaging at T42 and almost neutral at T63 in the range of day 1 to day 4. Beyond the day 4 there is a clear improvement at all resolutions.展开更多
The objective of this study is to demonstrate that tensile stress resulting due to applied force on cornea can be accurately measured by using a time-domain common-path optical coherence tomography （OCT） system with...The objective of this study is to demonstrate that tensile stress resulting due to applied force on cornea can be accurately measured by using a time-domain common-path optical coherence tomography （OCT） system with an external contact reference. The unique design of the common-path OCT is utilized to set up an imaging system in which a chicken eye is placed adjacent to a glass plate serving as the external reference plane for the imaging system. As the force is applied to the chicken eye, it presses against the reference glass plate. The modified OCT image obtained is used to calculate the size of contact area, which is then used to derive the tensile stress on the cornea. The drop in signal levels upon contact of reference glass plate with the tissue are extremely sharp because of the sharp decline in reference power levels itself, thus providing us with an accurate measurement of contact area. The experimental results were in good agreement with the numerical predictions. The results of this study might be useful in providing new insights and ideas to improve the precision and safety of currently used ophthalmic surgical techniques. This research outlines a method which could be used to provide high resolution OCT images and a precise feedback of the forces applied to the cornea simultaneously.展开更多
基金financially supported by the Natural Science Foundation of China(Grant 81072263,to Y.Z.)Chun Tsung Scholarship of Fudan University(to D.C.)
文摘Eleven recently completed toxicological studies were critically reviewed to identify toxicologically significant endpoints and dose-response information. Dose-response data were compiled and entered into the USEPA＇s benchmark dose software （BMDS） for calculation of a benchmark dose （BMD） and a benchmark dose low （BMDL）. After assessing 91 endpoints across the nine studies, a total of 23 of these endpoints were identified for BMD modeling, and BMDL estimates corresponding to various dose-response models were compiled for these separate endpoints. Thyroid, neurobehavior and reproductive endpoints for BDE-47, -99, -209 were quantitatively evaluated. According to methods and feature of each study, different uncertainty factor （UF） value was decided and subsequently reference doses （RfDs） were proposed. Consistent with USEPA, the lowest BMDLs of 2.10, 81.77, and 1698 I^g/kg were used to develop RfDs for BDE-47, -99, and -209, respectively. RfDs for BDE-99 and BDE-209 were comparable to EPA results, and however, RfD of BDE-47 was much lower than that of EPA, which may result from that reproductive/developmental proves to be more sensitive than neurobehavior for BDE-47 and the principal study uses very-low-dose exposure.
文摘In this paper, the authors develop the earlier work of Chen Jiabin et al. (1986). In order to reduce spectral truncation errors, the reference atmosphere has been introduced in ECMWF model, and the spectrally-represented variables, temperature, geopotential height and orography, are replaced by their deviations from the reference atmosphere. Two modified semi- implicit schemes have been proposed to alleviate the computational instability due to the introduction of reference atmosphere. Concerning the deviation of surface geopotential height from reference atmosphere, an exact computational formulation has been used instead of the approximate one in the earlier work. To re duce aliasing errors in the computations of the deviation of the surface geopotential height, a spectral fit has been used slightly to modify the original Gaussian grid-point values of orography.A series of experiments has been performed in order to assess the impact of the reference atmosphere on ECMWF medium- range forecasts at the resolution T21, T42 and T63. The results we have obtained reveal that the reference atmosphere introduced in ECMWF spectral model is generally beneficial to the mean statistical scores of 1000-200 hPa height 10-day forecasts over the globe. In the Southern Hemisphere, it is a clear improvement for T21, T42 and T63 throughout the 10-day forecast period. In the Northern Hemisphere, the impact of the reference atmos phere on anomaly correlation is positive for resolution T21, a very slightly damaging at T42 and almost neutral at T63 in the range of day 1 to day 4. Beyond the day 4 there is a clear improvement at all resolutions.
文摘The objective of this study is to demonstrate that tensile stress resulting due to applied force on cornea can be accurately measured by using a time-domain common-path optical coherence tomography （OCT） system with an external contact reference. The unique design of the common-path OCT is utilized to set up an imaging system in which a chicken eye is placed adjacent to a glass plate serving as the external reference plane for the imaging system. As the force is applied to the chicken eye, it presses against the reference glass plate. The modified OCT image obtained is used to calculate the size of contact area, which is then used to derive the tensile stress on the cornea. The drop in signal levels upon contact of reference glass plate with the tissue are extremely sharp because of the sharp decline in reference power levels itself, thus providing us with an accurate measurement of contact area. The experimental results were in good agreement with the numerical predictions. The results of this study might be useful in providing new insights and ideas to improve the precision and safety of currently used ophthalmic surgical techniques. This research outlines a method which could be used to provide high resolution OCT images and a precise feedback of the forces applied to the cornea simultaneously.
