6,482 research outputs found
The Heyday of the Balance of Power: Frederick The Great and the Decline of the Old Regime
The essential purpose of balance of power was the perpetuation of the status quo that guaranteed the sovereignty of the weak. Then came Frederick II whose eschewal of inhibition, consensus, and civility in statecraft pruned the golden age to but a golden moment
Exploiting American Vulnerabilities
Some aspects of American security are widely thought to be vulnerable to Soviet exploitation and indeed many are. This paper examines several problems and areas and finds them less vulnerable than some otherwise have thought. Prudence, however, remains the final recommendation
The Evolution of International Order and the Future of the American Naval Presence Mission
Much attention has been given to the role of seapower and naval forces in the conduct of war. The Navy\u27s combat capability is obvious and its rationale is increasingly discussed in terms both of the deterrence of conflict and of the political uses of seapower
The Changing Context of American Seapower
The Expansion of Force. Among the more important of the new complexities confronting both analysis and policy are those surrounding the use of force. For almost 300 years prior to the end of World War II, the pursuit of security by nation-states has been the central dynamic of international politics, The correlative of this condition has been an expansion of the capacity of the nation-state to deploy and use military power. During the last 150 years of this expansionist phase 1 of the role of military power in international politics an important paradox emerged: the use of military power could result in enormous disorder but, under certain circumstances, order as well
Intensity-Resolved Above Threshold Ionization of Xenon with Short Laser Pulses
We present intensity-resolved above threshold ionization (ATI) spectra of
xenon using an intensity scanning and deconvolution technique. Experimental
data were obtained with laser pulses of 58 fs and central wavelength of 800 nm
from a chirped-pulse amplifier. Applying a deconvolution algorithm, we obtained
spectra that have higher contrast and are in excellent agreement with
characteristic 2 and 10 cutoff energies contrary to that found for
raw data. The retrieved electron ionization probability is consistent with the
presence of a second electron from double ionization. This recovered ionization
probability is confirmed with a calculation based on the PPT tunneling
ionization model [Perelomov, Popov, and Terent'ev, Sov. Phys. JETP 23, 924
(1966)]. Thus, the measurements of photoelectron yields and the proposed
deconvolution technique allowed retrieval of more accurate spectroscopic
information from the ATI spectra and ionization probability features that are
usually concealed by volume averaging.Comment: 21 pages, 7 figure
Mixed layer temperature response to the southern annular mode: Mechanisms and model representation
Previous studies have shown that simulated sea surface temperature (SST) responses to the southern annular mode (SAM) in phase 3 of the Coupled Model Intercomparison Project (CMIP3) climate models compare poorly to the observed response. The reasons behind these model inaccuracies are explored. The ocean mixed layer heat budget is examined in four of the CMIP3 models and by using observations- reanalyses. The SST response to the SAM is predominantly driven by sensible and latent heat flux and Ekman heat transport anomalies. The radiative heat fluxes play a lesser but nonnegligible role. Errors in the simulated SST responses are traced back to deficiencies in the atmospheric response to the SAM. The models exaggerate the surface wind response to the SAM leading to large unrealistic Ekman transport anomalies. During the positive phase of the SAM, this results in excessive simulated cooling in the 40Β°-65Β°S latitudes. Problems with the simulated wind stress responses, which relate partly to errors in the simulated winds themselves and partly to the transfer coefficients used in the models, are a key cause of the errors in the SST response. In the central Pacific sector (90Β°-150Β°W), errors arise because the simulated SAM is too zonally symmetric. Substantial errors in the net shortwave radiation are also found, resulting from a poor repre- sentation of the changes in cloud cover associated with the SAM. The problems in the simulated SST re- sponses shown by this study are comparable to deficiencies previously identified in the CMIP3 multimodel mean. Therefore, it is likely that the deficiencies identified here are common to other climate models
The recognition of ubiquitinated proteins by the proteasome.
The ability of ubiquitin to form up to eight different polyubiquitin chain linkages generates complexity within the ubiquitin proteasome system, and accounts for the diverse roles of ubiquitination within the cell. Understanding how each type of ubiquitin linkage is correctly interpreted by ubiquitin binding proteins provides important insights into the link between chain recognition and cellular fate. A major function of ubiquitination is to signal degradation of intracellular proteins by the 26S proteasome. Lysine-48 (K48) linked polyubiquitin chains are well established as the canonical signal for proteasomal degradation, but recent studies show a role for other ubiquitin linked chains in facilitating degradation by the 26S proteasome. Here, we review how different types of polyubiquitin linkage bind to ubiquitin receptors on the 26S proteasome, how they signal degradation and discuss the implications of ubiquitin chain linkage in regulating protein breakdown by the proteasome.JAN is supported by a Wellcome Trust Senior Clinical Research Fellowship (102770/Z/13/Z). The Cambridge Institute for Medical Research is in receipt of a Wellcome Trust Strategic Award (100140).This is the final published version. It first appeared from Springer via https://doi.org/10.1007/s00018-016-2255-
MC: Multi-wavelength and dynamical analysis of the merging galaxy cluster ZwCl 0008.8+5215: An older and less massive Bullet Cluster
We analyze a rich dataset including Subaru/SuprimeCam, HST/ACS and WFC3,
Keck/DEIMOS, Chandra/ACIS-I, and JVLA/C and D array for the merging galaxy
cluster ZwCl 0008.8+5215. With a joint Subaru/HST weak gravitational lensing
analysis, we identify two dominant subclusters and estimate the masses to be
M
and 1.2 M. We estimate the
projected separation between the two subclusters to be
924 kpc. We perform a clustering analysis on
confirmed cluster member galaxies and estimate the line of sight velocity
difference between the two subclusters to be 92164 km s. We
further motivate, discuss, and analyze the merger scenario through an analysis
of the 42 ks of Chandra/ACIS-I and JVLA/C and D polarization data. The X-ray
surface brightness profile reveals a remnant core reminiscent of the Bullet
Cluster. The X-ray luminosity in the 0.5-7.0 keV band is
1.70.110 erg s and the X-ray
temperature is 4.900.13 keV. The radio relics are polarized up to 40.
We implement a Monte Carlo dynamical analysis and estimate the merger velocity
at pericenter to be 1800 km s. ZwCl
0008.8+5215 is a low-mass version of the Bullet Cluster and therefore may prove
useful in testing alternative models of dark matter. We do not find significant
offsets between dark matter and galaxies, as the uncertainties are large with
the current lensing data. Furthermore, in the east, the BCG is offset from
other luminous cluster galaxies, which poses a puzzle for defining dark matter
-- galaxy offsets.Comment: 22 pages, 19 figures, accepted for publication in the Astrophysical
Journal on March 13, 201
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