Aim: To develop an algorithm for use in population-based studies to assess testicular function by measurements of totalurinary follicle stimulating hormone (FSH). Methods: Total concentrations of urinary FSH were meas...Aim: To develop an algorithm for use in population-based studies to assess testicular function by measurements of totalurinary follicle stimulating hormone (FSH). Methods: Total concentrations of urinary FSH were measured in a groupof 44 men at the University of California, Davis (UCD) and were compared to FSH measurements in serum. On thebasis of these and other published data, a urinary FSH value of >2 ng/mg creatinine (Cr) was selected as the cutoffpoint to identify men with elevated serum FSH ( > 12 IU/L) or low sperm counts ( < 20 million/mL). Results: Thesensitivity and specificity of this algorithm for detecting elevated serum FSH in a group of 58 agricultural workers in thePeople's Republic of China were 100 % and 50 %, respectively. The sensitivity and specificity of this algorithm fordetecting low sperm counts in a population of 105 infertility patients at UCD were 58 % and 76 %, respectively.Conclusion: This test may have particular value in identifying populations with no evidence of testicular toxicity, andin which labor-intensive semen studies may not be feasible.展开更多
Definition of a new geologic period for the Iast interval of the Proterozoic Eon, the Ediacaran, was recently ratified by the IUGS. The Ediacaran Period is the first Proterozoic period to be recognized on the basis of...Definition of a new geologic period for the Iast interval of the Proterozoic Eon, the Ediacaran, was recently ratified by the IUGS. The Ediacaran Period is the first Proterozoic period to be recognized on the basis of chronostratigraphic criteria, the first internationally ratified, chronostratigraphically defined period of any age to be introduced in more than 120 years, and the first to be defined by a “golden spike” in the Southern hemisphere.展开更多
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Historians of modern science have good reasons to be grateful to Paul Arthur Schilpp, professor of philosophy and Methodist clergyman but better known as the editor of a series of volumes on "Living Philosophe...Ⅰ
Historians of modern science have good reasons to be grateful to Paul Arthur Schilpp, professor of philosophy and Methodist clergyman but better known as the editor of a series of volumes on "Living Philosophers," including several on scientist - philosophers. His motto was: "The asking of questions about a philosopher' s meaning while he is alive." And to his everlasting credit, he persuaded Albert Einstein to do what he had resisted all his years: to sit down to write, in 1946 at age sixty - seven, an extensive autobiography- forty - five pages long in print.展开更多
Well-defined and controllable one-dimensional (1D) nanostructures of fullerene derivative have been pre- pared by an electrophoretic template synthesis method. The clusters of fullerene derivative formed in mixed solv...Well-defined and controllable one-dimensional (1D) nanostructures of fullerene derivative have been pre- pared by an electrophoretic template synthesis method. The clusters of fullerene derivative formed in mixed solvents are introduced into the channels of porous alumina templates through a dc electric field. Four types of 1D nanostructures (solid nanowires, solid-wall nanotubes, porous nanowires and porous-wall nanotubes) have been obtained by changing the deposition parameters. This approach opens a new avenue to assemble fullerene derivatives, endohedral fullerenes, as well as other functional organic compounds, which can form clusters in 1D nanostructure arrays for applications in chemical sensors, light energy conversion devices and nano- scale electronic and optoelectronic devices.展开更多
Wireless transmission is becoming increasing ubiquitous, but there is a big black hole in the security of this kind of network. Although IEEE 802.11 provides an optional Wired Equivalent Privacy (WEP) to implement the...Wireless transmission is becoming increasing ubiquitous, but there is a big black hole in the security of this kind of network. Although IEEE 802.11 provides an optional Wired Equivalent Privacy (WEP) to implement the authentication and confidentiality, it leaves a lot of vulnerabilities and threats. This paper proposes a protocol called SPRNG for wireless data-link layer security. SPRNG is based on the sender and receiver who generate in a synchronized way a pseudo-random number sequence. In each transmission, the sender and receiver use a pair of random numbers, one for data frame authentication, and the other for encryption key. The random numbers are used as 'one-time passwords' for sender authentication and as fresh encryption keys for each frame. SPRNG is designed to be compatible with the existing 802.11 products. Like WEP, the current 802.11 security protocol, SPRNG uses a symmetric key as its seed. SPRNG has already been simulated and tested in experiment, it shows that SPRNG has stronger Security than WEP because it reveals little information for attackers. The key problem of SPRNG, synchronization loss problem, is also presented. Though motivated by wireless security, SPRNG is generic for many other applications, especially in the point to point communication.展开更多
The de facto US dollar-pegged exchange rate regime of renminbi has held back thedevelopment of the foreign exchange market. The adoption of the real managed floatingregime in the near future can only be achieved in th...The de facto US dollar-pegged exchange rate regime of renminbi has held back thedevelopment of the foreign exchange market. The adoption of the real managed floatingregime in the near future can only be achieved in the process of the development of foreignexchange market. The market development mainly includes the increase of transactionentities, the introduction of a dealer system, the development of the forward market, and theestablishment of an independent settlement and clearing house. The central banksintervention in the market should be reduced dramatically and a level playing field shouldbe created for all market participants to foster competition. To prevent the systemic financialrisks, it is crucial to strengthen information disclosure and improve the policy coordinationof various regulatory authorities. The central bank needs to closely monitor transactionentities as a lender of last resort.展开更多
基金Project supported by National Institute of Health Grants ES04699, ES06198 and ES05707
文摘Aim: To develop an algorithm for use in population-based studies to assess testicular function by measurements of totalurinary follicle stimulating hormone (FSH). Methods: Total concentrations of urinary FSH were measured in a groupof 44 men at the University of California, Davis (UCD) and were compared to FSH measurements in serum. On thebasis of these and other published data, a urinary FSH value of >2 ng/mg creatinine (Cr) was selected as the cutoffpoint to identify men with elevated serum FSH ( > 12 IU/L) or low sperm counts ( < 20 million/mL). Results: Thesensitivity and specificity of this algorithm for detecting elevated serum FSH in a group of 58 agricultural workers in thePeople's Republic of China were 100 % and 50 %, respectively. The sensitivity and specificity of this algorithm fordetecting low sperm counts in a population of 105 infertility patients at UCD were 58 % and 76 %, respectively.Conclusion: This test may have particular value in identifying populations with no evidence of testicular toxicity, andin which labor-intensive semen studies may not be feasible.
文摘Definition of a new geologic period for the Iast interval of the Proterozoic Eon, the Ediacaran, was recently ratified by the IUGS. The Ediacaran Period is the first Proterozoic period to be recognized on the basis of chronostratigraphic criteria, the first internationally ratified, chronostratigraphically defined period of any age to be introduced in more than 120 years, and the first to be defined by a “golden spike” in the Southern hemisphere.
文摘Ⅰ
Historians of modern science have good reasons to be grateful to Paul Arthur Schilpp, professor of philosophy and Methodist clergyman but better known as the editor of a series of volumes on "Living Philosophers," including several on scientist - philosophers. His motto was: "The asking of questions about a philosopher' s meaning while he is alive." And to his everlasting credit, he persuaded Albert Einstein to do what he had resisted all his years: to sit down to write, in 1946 at age sixty - seven, an extensive autobiography- forty - five pages long in print.
文摘Well-defined and controllable one-dimensional (1D) nanostructures of fullerene derivative have been pre- pared by an electrophoretic template synthesis method. The clusters of fullerene derivative formed in mixed solvents are introduced into the channels of porous alumina templates through a dc electric field. Four types of 1D nanostructures (solid nanowires, solid-wall nanotubes, porous nanowires and porous-wall nanotubes) have been obtained by changing the deposition parameters. This approach opens a new avenue to assemble fullerene derivatives, endohedral fullerenes, as well as other functional organic compounds, which can form clusters in 1D nanostructure arrays for applications in chemical sensors, light energy conversion devices and nano- scale electronic and optoelectronic devices.
文摘Wireless transmission is becoming increasing ubiquitous, but there is a big black hole in the security of this kind of network. Although IEEE 802.11 provides an optional Wired Equivalent Privacy (WEP) to implement the authentication and confidentiality, it leaves a lot of vulnerabilities and threats. This paper proposes a protocol called SPRNG for wireless data-link layer security. SPRNG is based on the sender and receiver who generate in a synchronized way a pseudo-random number sequence. In each transmission, the sender and receiver use a pair of random numbers, one for data frame authentication, and the other for encryption key. The random numbers are used as 'one-time passwords' for sender authentication and as fresh encryption keys for each frame. SPRNG is designed to be compatible with the existing 802.11 products. Like WEP, the current 802.11 security protocol, SPRNG uses a symmetric key as its seed. SPRNG has already been simulated and tested in experiment, it shows that SPRNG has stronger Security than WEP because it reveals little information for attackers. The key problem of SPRNG, synchronization loss problem, is also presented. Though motivated by wireless security, SPRNG is generic for many other applications, especially in the point to point communication.
文摘The de facto US dollar-pegged exchange rate regime of renminbi has held back thedevelopment of the foreign exchange market. The adoption of the real managed floatingregime in the near future can only be achieved in the process of the development of foreignexchange market. The market development mainly includes the increase of transactionentities, the introduction of a dealer system, the development of the forward market, and theestablishment of an independent settlement and clearing house. The central banksintervention in the market should be reduced dramatically and a level playing field shouldbe created for all market participants to foster competition. To prevent the systemic financialrisks, it is crucial to strengthen information disclosure and improve the policy coordinationof various regulatory authorities. The central bank needs to closely monitor transactionentities as a lender of last resort.
