On the basis of radiation transfer theory,adopting improved two-stream algorithm incorporated with addingalgorithm,we build up a theoretical calculation model of shortwave radiation for the earth-atmosphere system whi...On the basis of radiation transfer theory,adopting improved two-stream algorithm incorporated with addingalgorithm,we build up a theoretical calculation model of shortwave radiation for the earth-atmosphere system whichcan be applied with satellite data.The model can calculate direct solar radiation,scattering solar radiation,heating rateand other physical quantities of radiation field at every layer of the atmosphere and on the earth’s surface,if the under-ground reflectance or the planetary albedo obtained from satellite can be known.The model can be used in clear orcloudy atmosphere,and its calculating speed is fairly fast.We think that the model can be incorporated into large-scaleand mesoscale climatic models for the consideration of radiation calculation,and also it is useful for the utilization of so-lar energy.展开更多
Objective:To review follow-up imaging after equivocal bone scans in men with castration resistant prostate cancer(CRPC)and examine the characteristics of equivocal bone scans that are associated with positive follow-u...Objective:To review follow-up imaging after equivocal bone scans in men with castration resistant prostate cancer(CRPC)and examine the characteristics of equivocal bone scans that are associated with positive follow-up imaging.Methods:We identified 639 men from five Veterans Affairs Hospitals with a technetium-99m bone scan after CRPC diagnosis,of whom 99(15%)had equivocal scans.Men with equivocal scans were segregated into“high-risk”and“low-risk”subcategories based upon wording in the bone scan report.All follow-up imaging(bone scans,computed tomography[CT],magnetic resonance imaging[MRI],and X-rays)in the 3 months after the equivocal scan were reviewed.Variables were compared between patients with a positive vs.negative follow-up imaging after an equivocal bone scan.Results:Of 99 men with an equivocal bone scan,43(43%)received at least one follow-up imaging test,including 32/82(39%)with low-risk scans and 11/17(65%)with high-risk scans(p=0.052).Of follow-up tests,67%were negative,14%were equivocal,and 19%were positive.Among those who underwent follow-up imaging,3/32(9%)low-risk men had metastases vs.5/11(45%)high-risk men(p=0.015).Conclusion:While 19%of all men who received follow-up imaging had positive follow-up imaging,only 9%of those with a low-risk equivocal bone scan had metastases versus 45%of those with high-risk.These preliminary findings,if confirmed in larger studies,suggest follow-up imaging tests for low-risk equivocal scans can be delayed while high-risk equivocal scans should receive follow-up imaging.展开更多
Genetic screening has its uses:It helped A-list actor Angelina Jolie,for example,determine that she was at a high risk of breast cancer,leading to a preventative mastectomy.But what genetic screening can’t demonstrat...Genetic screening has its uses:It helped A-list actor Angelina Jolie,for example,determine that she was at a high risk of breast cancer,leading to a preventative mastectomy.But what genetic screening can’t demonstrate is whether,broadly speaking,your child will have an aptitude for mathematics or sports.Certain specific health problems,yes;but sweeping statements about the future character of an adult?The scientific evidence for such tests was展开更多
The following problem is called the everywhere-cover problem:“Given a set of dependencies over a database scheme,is the set of dependencies explicitly given for each relation scheme equivalent to the dependencies imp...The following problem is called the everywhere-cover problem:“Given a set of dependencies over a database scheme,is the set of dependencies explicitly given for each relation scheme equivalent to the dependencies implied for that relation scheme?”It is shown that when the everywhere-cover problem has a ‘yes’ answer,examining only the dependencies explicitly given will suffice to test 3NF,BCNF and 4NF of a database scheme.But this does not hold for 2NF.Consequently,in such cases,tests of BCNF and 4NF all take polynomial time.Then a proof is given that test of 3NF of a database scheme is Co-NP-complete,and from this result it is shown that everywhere-cover is also Co-NP-complete when only functional dependencies are allowed.These results lead to doubt the truth of the well believed conjec- ture that no polynomial time algorithm for designing a Iossless BCNF database scheme is likely to exist.展开更多
A novel fabrication method of multi-core photonic crystal fibers is proposed on the basis of a fiber-embedded technique. A taper tower is used to modify the structures of the fiber preform, and four steps of fiber fab...A novel fabrication method of multi-core photonic crystal fibers is proposed on the basis of a fiber-embedded technique. A taper tower is used to modify the structures of the fiber preform, and four steps of fiber fabrication and different structures of fiber samples are given. The mode structures and beating characteristics of a photonic crystal fiber sample with two successive cores are investigated in detail with the help of a supercontinuum light source, a charge-coupled device （CCD） camera, and an optical spectrum analyzer. The test results show a clear beating phenomenon between two orthotropic polarization modes with a 2.8-nm peak interval in wavelength.展开更多
文摘On the basis of radiation transfer theory,adopting improved two-stream algorithm incorporated with addingalgorithm,we build up a theoretical calculation model of shortwave radiation for the earth-atmosphere system whichcan be applied with satellite data.The model can calculate direct solar radiation,scattering solar radiation,heating rateand other physical quantities of radiation field at every layer of the atmosphere and on the earth’s surface,if the under-ground reflectance or the planetary albedo obtained from satellite can be known.The model can be used in clear orcloudy atmosphere,and its calculating speed is fairly fast.We think that the model can be incorporated into large-scaleand mesoscale climatic models for the consideration of radiation calculation,and also it is useful for the utilization of so-lar energy.
基金The study was supported by the NIH/NCI under Award Number P50CA09231(WJA)and NIH K24 CA160653(SJF).
文摘Objective:To review follow-up imaging after equivocal bone scans in men with castration resistant prostate cancer(CRPC)and examine the characteristics of equivocal bone scans that are associated with positive follow-up imaging.Methods:We identified 639 men from five Veterans Affairs Hospitals with a technetium-99m bone scan after CRPC diagnosis,of whom 99(15%)had equivocal scans.Men with equivocal scans were segregated into“high-risk”and“low-risk”subcategories based upon wording in the bone scan report.All follow-up imaging(bone scans,computed tomography[CT],magnetic resonance imaging[MRI],and X-rays)in the 3 months after the equivocal scan were reviewed.Variables were compared between patients with a positive vs.negative follow-up imaging after an equivocal bone scan.Results:Of 99 men with an equivocal bone scan,43(43%)received at least one follow-up imaging test,including 32/82(39%)with low-risk scans and 11/17(65%)with high-risk scans(p=0.052).Of follow-up tests,67%were negative,14%were equivocal,and 19%were positive.Among those who underwent follow-up imaging,3/32(9%)low-risk men had metastases vs.5/11(45%)high-risk men(p=0.015).Conclusion:While 19%of all men who received follow-up imaging had positive follow-up imaging,only 9%of those with a low-risk equivocal bone scan had metastases versus 45%of those with high-risk.These preliminary findings,if confirmed in larger studies,suggest follow-up imaging tests for low-risk equivocal scans can be delayed while high-risk equivocal scans should receive follow-up imaging.
文摘Genetic screening has its uses:It helped A-list actor Angelina Jolie,for example,determine that she was at a high risk of breast cancer,leading to a preventative mastectomy.But what genetic screening can’t demonstrate is whether,broadly speaking,your child will have an aptitude for mathematics or sports.Certain specific health problems,yes;but sweeping statements about the future character of an adult?The scientific evidence for such tests was
基金Supported by the National Natural Science Foundation of China.
文摘The following problem is called the everywhere-cover problem:“Given a set of dependencies over a database scheme,is the set of dependencies explicitly given for each relation scheme equivalent to the dependencies implied for that relation scheme?”It is shown that when the everywhere-cover problem has a ‘yes’ answer,examining only the dependencies explicitly given will suffice to test 3NF,BCNF and 4NF of a database scheme.But this does not hold for 2NF.Consequently,in such cases,tests of BCNF and 4NF all take polynomial time.Then a proof is given that test of 3NF of a database scheme is Co-NP-complete,and from this result it is shown that everywhere-cover is also Co-NP-complete when only functional dependencies are allowed.These results lead to doubt the truth of the well believed conjec- ture that no polynomial time algorithm for designing a Iossless BCNF database scheme is likely to exist.
基金the China Scholarship Council(CSC) and the Research Foundation of Harbin Engineering University
文摘A novel fabrication method of multi-core photonic crystal fibers is proposed on the basis of a fiber-embedded technique. A taper tower is used to modify the structures of the fiber preform, and four steps of fiber fabrication and different structures of fiber samples are given. The mode structures and beating characteristics of a photonic crystal fiber sample with two successive cores are investigated in detail with the help of a supercontinuum light source, a charge-coupled device （CCD） camera, and an optical spectrum analyzer. The test results show a clear beating phenomenon between two orthotropic polarization modes with a 2.8-nm peak interval in wavelength.
