948 resultados para gravitational capture


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Gravitational lenses, besides being interesting in their own right, have been demonstrated to be suitable as “gravitational standard rulers” for the measurement of the rate of expansion of the Universe (Ho), as well as to constrain the values of the cosmological parameters such as Ωo and Λo that control the evolution of the volume of the Universe with cosmic time.

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Most of the known cases of strong gravitational lensing involve multiple imaging of an active galactic nucleus. The properties of lensed active galactic nuclei make them promising systems for astrophysical applications of gravitational lensing; in particular, they show structure on scales of milliseconds of arc to tens of seconds of arc, they are variable, and they are polarized. More than 20 cases of strong gravitational lenses are now known, and about half of them are radio sources. High-resolution radio imaging is making possible the development of well-constrained lens models. Variability studies at radio and optical wavelengths are beginning to yield results of astrophysical interest, such as an independent measure of the distance scale and limits on source sizes.

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As the first step of a research program aimed at developing a bispecific monoclonal antibody system for the delivery of boron-rich molecules to tumor cells for boron neutron capture therapy, monoclonal antibodies (mAbs) were produced against an anionic nido-carborane derivative, 4-[7,8-dicarbadodecahydroundecaborat(-1)-7-yl]butanoic acid. Two IgG subclass mAbs, designated HAW101 and HAW102, were identified that specifically bound the anionic nido-carborane hapten, as well as a variety of other anionic nido-carborane cage derivatives. By using surface plasmon resonance technology, the affinity constants of HAW101 and HAW102 were determined to be 1.9 x 10(9) and 6.8 x 10(8) M-1, respectively. A diverse array of 7-substituted and 7,8-disubstituted anionic nido-carborane derivatives reacted with the mAb HAW101 in competition ELISA, whereas anionic closo-polyhedral boranes showed negligible binding, suggesting a role for the open nido-carborane cage structure. These results suggest that mAbs such as HAW101, which bind anionic nido-carboranes, are useful in the development of bispecific mAbs for specific targeting and enhanced boron delivery to tumor sites.

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CO2 capture by solid sorbents is a physisorption process in which the gas molecules are adsorbed in a different porosity range, depending on the temperature and pressure of the capture conditions. Accordingly, CO2 capture capacities can be enhanced if the sorbent has a proper porosity development and a suitable pore size distribution. Thus, the main objective of this work is to maximize the CO2 capture capacity at ambient temperature, elucidating which is the most suitable porosity that the adsorbent has to have as a function of the emission source conditions. In order to do so, different activated carbons have been selected and their CO2 capture capacities have been measured. The obtained results show that for low CO2 pressures (e.g., conditions similar to post-combustion processes) the sorbent should have the maximum possible volume of micropores smaller than 0.7 nm. However, the sorbent requires the maximum possible total micropore volume when the capture is performed at high pressures (e.g., conditions similar to oxy-combustion or pre-combustion processes). Finally, this study also analyzes the important influence that the sorbent density has on the CO2 capture capacity, since the adsorbent will be confined in a bed with a restricted volume.

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Activated carbons prepared from petroleum pitch and using KOH as activating agent exhibit an excellent behavior in CO2 capture both at atmospheric (∼168 mg CO2/g at 298 K) and high pressure (∼1500 mg CO2/g at 298 K and 4.5 MPa). However, an exhaustive evaluation of the adsorption process shows that the optimum carbon structure, in terms of adsorption capacity, depends on the final application. Whereas narrow micropores (pores below 0.6 nm) govern the sorption behavior at 0.1 MPa, large micropores/small mesopores (pores below 2.0–3.0 nm) govern the sorption behavior at high pressure (4.5 MPa). Consequently, an optimum sorbent exhibiting a high working capacity for high pressure applications, e.g., pressure-swing adsorption units, will require a poorly-developed narrow microporous structure together with a highly-developed wide microporous and small mesoporous network. The appropriate design of the preparation conditions gives rise to carbon materials with an extremely high delivery capacity ∼1388 mg CO2/g between 4.5 MPa and 0.1 MPa. Consequently, this study provides guidelines for the design of carbon materials with an improved ability to remove carbon dioxide from the environment at atmospheric and high pressure.

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Manuscript narrative, signed by John Campion and Joseph Knills; dated at Carbonnear Is., Newfoundland, 14 May 1709.

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From the Introduction. In the long shadow of the euro-area crisis, the relationship between governments and their banks has been brought to the the centre of the policy debate in Europe by the implementation of regulatory reforms, the risks associated with financial fragmentation, and the fight to sustain the flow of credit to governments and corporates. The attempt to interpret the patterns of pressure and influence running between governments and their financial system has led commentators to rediscover and give new life to concepts originating from academic debates of the 1970s such as “regulatory capture” and “financial repression”. Government agencies have been frequently described as being at the mercy of the financial sector, often allowing financial interests to hijack political, regulatory and supervisory processes in order to favouring their own private interests over the public good1. An opposite view has instead pointed the finger at governments, which have often been portrayed as subverting markets and abusing the financial system to their benefit, either in order to secure better financing conditions to overcome their own financial difficulties, or with the objective of directing credit to certain sectors of the economy, “repressing” the free functioning of financial markets and potentially the private interests of some of its participants2

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There is growing worldwide concern about bias in the enforcement of competition law in favour of domestic firms. Even seemingly neutral antitrust laws can lead discrimination if they are enforced selectively. - Authors investigate the distortions that national competition authorities generate when they pursue non-competition goals in favour of domestic firms, and discuss ways to address this negative policy development in a globalised world. - The distortions identified in the paper would dissipate if governments agreed that the sole objective of competition law ought to be the protection of consumer welfare that competition-law institutions ought to be protected against capture. - A realistic and effective way to prompt international convergence towards independent enforcement of competition laws is through the inclusion of competition clauses in bilateral trade agreements and the development of dispute-resolution mechanisms.

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Work performed at the Argonne National Laboratory.

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"This work was supported in part by the National Science Foundation under grant G9503."

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Kesav the Elder (outline and portraits), Chetar Muni (paintings); 1 ft. 3 in.x 8 13/16 in.x 35/64 in.; opaque watercolor and gold on paper

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Kesav the Elder (outline and portraits), Chetar Muni (paintings); 1 ft. 19/32 in.x 7 31/64 in.; opaque watercolor and gold on paper