Phase-coherent optical pulse synthesis from separate femtosecond lasers     

Shelton RK  Ma LS  Kapteyn HC  Murnane MM  Hall JL  Ye J 《Science (New York, N.Y.)》2001,293(5533):1286-1289

We generated a coherently synthesized optical pulse from two independent mode-locked femtosecond lasers, providing a route to extend the coherent bandwidth available for ultrafast science. The two separate lasers (one centered at 760 nanometers wavelength, the other at 810 nanometers) are tightly synchronized and phase-locked. Coherence between the two lasers is demonstrated via spectral interferometry and second-order field cross-correlation. Measurements reveal a coherently synthesized pulse that has a temporally narrower second-order autocorrelation width and that exhibits a larger amplitude than the individual laser outputs. This work represents a new and flexible approach to the synthesis of coherent light.  相似文献   

EDWARD COWLES     

Hall GS 《Science (New York, N.Y.)》1919,50(1284):132-133

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Flora north america     

Hall AV 《Science (New York, N.Y.)》1973,182(4113):652

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Linkage of early-onset familial breast cancer to chromosome 17q21   总被引：191，自引：0，他引：191  

J M Hall  M K Lee  B Newman  J E Morrow  L A Anderson  B Huey  M C King 《Science (New York, N.Y.)》1990,250(4988):1684-1689

Human breast cancer is usually caused by genetic alterations of somatic cells of the breast, but occasionally, susceptibility to the disease is inherited. Mapping the genes responsible for inherited breast cancer may also allow the identification of early lesions that are critical for the development of breast cancer in the general population. Chromosome 17q21 appears to be the locale of a gene for inherited susceptibility to breast cancer in families with early-onset disease. Genetic analysis yields a lod score (logarithm of the likelihood ratio for linkage) of 5.98 for linkage of breast cancer susceptibility to D17S74 in early-onset families and negative lod scores in families with late-onset disease. Likelihood ratios in favor of linkage heterogeneity among families ranged between 2000:1 and greater than 10(6):1 on the basis of multipoint analysis of four loci in the region.  相似文献   

Homeo domain of the yeast repressor alpha 2 is a sequence-specific DNA-binding domain but is not sufficient for repression   总被引：19，自引：0，他引：19  

M N Hall  A D Johnson 《Science (New York, N.Y.)》1987,237(4818):1007-1012

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New routes to early memories   总被引：3，自引：0，他引：3  

D Kucharski  W G Hall 《Science (New York, N.Y.)》1987,238(4828):786-788

Stimulation of one side of the olfactory system during training with odor-milk pairings in neonatal rats results in their ability to recall an odor memory by using the trained but not the untrained side of the brain. In 12-day-old rats, olfactory learning can be recalled by stimulation of either the trained or untrained side. The development of bilateral recall reflects the maturation of olfactory commissural pathways that provide access to the olfactory memory stored on the contralateral side. Furthermore, the commissural pathways need not be present at the time of memory formation but can establish new and specific access to already existing olfactory memories.  相似文献   

Cytokinins in the soluble RNA of plant tissues   总被引：35，自引：0，他引：35  

R H Hall  L Csonka  H David  B McLennan 《Science (New York, N.Y.)》1967,156(771):69-71

The cytokinin, N(6)-(Delta(2)-isopentenyl) adenosine occurs in the soluble RNA of yeast and mammalian tissue and has now been detected in plant soluble RNA. A hydroxylated derivative of this cytokinin 6-(cis-4-hydroxy-3-methylbut-2-enylamino)-9-,beta-D-ribofuranosylpurine has also been identified as a constituent of plant soluble RNA.  相似文献   

Association between potassium concentration and serological type of sheep red blood cells   总被引：4，自引：0，他引：4  

B A Rasmusen  J G Hall 《Science (New York, N.Y.)》1966,151(717):1551-1552

When red blood cells from 115 sheep were classified for the presence or absence of antigenic factor M and for high (as opposed to low) potassium concentration levels, the cells of the 22 M-negative sheep were low in potassium.  相似文献   

Energy and the u.s. Economy: a biophysical perspective   总被引：1，自引：0，他引：1  

Cleveland CJ  Costanza R  Hall CA  Kaufmann R 《Science (New York, N.Y.)》1984,225(4665):890-897

A series of hypotheses is presented about the relation of national energy use to national economic activity (both time series and cross-sectional) which offer a different perspective from standard economics for the assessment of historical and current economic events. The analysis incorporates nearly 100 years of time series data and 3 years of cross-sectional data on 87 sectors of the United States economy. Gross national product, labor productivity, and price levels are all correlated closely with various aspects of energy use, and these correlations are improved when corrections are made for energy quality. A large portion of the apparent increase in U.S. energy efficiency has been due to our ability to expand the relative use of high-quality fuels such as petroleum and electricity, and also to relative shifts in fuel use between sectors of the economy. The concept of energy return on investment is introduced as a major driving force in our economy, and data are provided which show a marked decline in energy return on investment for all our principal fuels in recent decades. Future economic growth will depend largely on the net energy yield of alternative fuel sources, and some standard economic models may need to be modified to account for the biophysical constraints on human economic activity.  相似文献   

Ultraviolet spectrometer observations of neptune and triton     

Broadfoot AL  Atreya SK  Bertaux JL  Blamont JE  Dessler AJ  Donahue TM  Forrester WT  Hall DT  Herbert F  Holberg JB  Hunter DM  Krasnopolsky VA  Linick S  Lunine JI  McConnell JC  Moos HW  Sandel BR  Schneider NM  Shemansky DE  Smith GR  Strobel DF  Yelle RV 《Science (New York, N.Y.)》1989,246(4936):1459-1466

Results from the occultation of the sun by Neptune imply a temperature of 750 +/- 150 kelvins in the upper levels of the atmosphere (composed mostly of atomic and molecular hydrogen) and define the distributions of methane, acetylene, and ethane at lower levels. The ultraviolet spectrum of the sunlit atmosphere of Neptune resembles the spectra of the Jupiter, Saturn, and Uranus atmospheres in that it is dominated by the emissions of H Lyman alpha (340 +/- 20 rayleighs) and molecular hydrogen. The extreme ultraviolet emissions in the range from 800 to 1100 angstroms at the four planets visited by Voyager scale approximately as the inverse square of their heliocentric distances. Weak auroral emissions have been tentatively identified on the night side of Neptune. Airglow and occultation observations of Triton's atmosphere show that it is composed mainly of molecular nitrogen, with a trace of methane near the surface. The temperature of Triton's upper atmosphere is 95 +/- 5 kelvins, and the surface pressure is roughly 14 microbars.  相似文献