AIDS meeting. Companies, donors pledge to close gap in AIDS treatment     

Cohen J 《Science (New York, N.Y.)》2000,289(5478):368-369

Although basic science and clinical research typically dominate at this biennial event, by far the most riveting sessions at the XIII International AIDS Conference here revolved around the thicket of issues that prevent poor people in sub-Saharan Africa--where a staggering 24.5 million people are estimated to be infected with HIV--from receiving the 14 anti-HIV treatments now used in wealthy countries. Pharmaceutical companies and donors last week loosed a flood of promises about removing barriers. Conference attendees welcomed the offers of help, but many stressed that much more will be needed.  相似文献   

Modifying the ionosphere with intense radio waves     

Utlaut WF  Cohen R 《Science (New York, N.Y.)》1971,174(4006):245-254

The ionospheric modification experiments provide an opportunity to better understand the aeronomy of the natural ionosphere and also afford the control of a naturally occurring plasma, which will make possible further progress in plasma physics. The ionospheric modification by powerful radio waves is analogous to studies of laser and microwave heating of laboratory plasmas (20). " Anomalous" reflectivity effects similar to the observed ionospheric attenuation have already been noted in plasmas modulated by microwaves, and anomalous heating may have been observed in plasmas irradiated by lasers. Contacts have now been established between the workers in these diverse areas, which span a wide range of the electromagnetic spectrum. Perhaps ionospheric modification will also be a valuable technique in radio communications.  相似文献   

Coesite and Shocked Quartz from Holleford Crater, Ontario, Canada     

Bunch TE  Cohen AJ 《Science (New York, N.Y.)》1963,142(3590):379-381

The Holleford Crater, a circular depression in southern Ontario, is filled with Paleozoic sediments and underlain by brecciated Precambrian igneous and metamorphic rocks. The presence of coesite in two core samples of this breccia has been established by petrographic and x-ray diflraction methods. Shattered quartz in the coesite-bearing samples exhibits planar fractures. The shocked quartz is the result of great shock pressures and the association of coesite with the shocked quartz strongly suggests that Holleford Crater originated from a hypervelocity impact.  相似文献   

Carbon nanotubes provide a charge     

Cohen AE 《Science (New York, N.Y.)》2003,300(5623):1235-6; author reply 1235-6

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John Crewdson: science journalist as investigator     

J Cohen 《Science (New York, N.Y.)》1991,254(5034):946-949

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M?ssbauer spectroscopy: recent developments     

R L Cohen 《Science (New York, N.Y.)》1972,178(63):828-835

In this review I have emphasized two basic points. First, M?ssbauer spectroscopy has been widely used as a tool for basic research in solid-state physics, chemical structure, and magnetism. Second, the technique has been applied to many analytical and materials science problems where the nature of the sample prevents the use of more traditional approaches. M?ssbauer spectroscopy research on frozen solutions, colloids, interface chemistry, and crystallographic transformations can be expected to increase rapidly in the next few years.  相似文献   

Study sections: does a superb system need a tune-up?     

Cohen J 《Science (New York, N.Y.)》1993,261(5129):1678-1679

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HIV/AIDS. Malawi: a suitable case for treatment     

Cohen J 《Science (New York, N.Y.)》2002,297(5583):927-929

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Profile. The risks--and rewards--of war zone research     

Cohen J 《Science (New York, N.Y.)》2000,288(5474):2159

Gulu, about 4 hours north of here by car, is in an "upcountry" region torn by armed conflict. So upcountry clinical researchers like Matthew Lukwiya, a native of the Gulu district, play a critical role--and win high praise from their colleagues.  相似文献   

Control of Aggregation in Dictyostelium discoideum by an External Periodic Pulse of Cyclic Adenosine Monophosphate     

Robertson A  Drage DJ  Cohen MH 《Science (New York, N.Y.)》1972,175(4019):333-335

We have induced and controlled normal aggregation of Dictyostelium discoideum amoebas by electrophoretic release of pulses of cyclic adenosine monophosphate from a microelectrode. This has yielded information about the sequence of development of aggregation competences during interphase. We believe that modifications of the technique will have wide application in investigations of other developing systems.  相似文献