567 research outputs found

    Implications of Two Peer Nuclear-Armed Adversaries on U.S. Deterrence Strategy and the Future of Arms Control Agreements

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    NPS NRP Technical ReportThis research will examine the implications of the rise of two near-peer, nuclear-armed adversaries for the United States, with an emphasis on the Russian role as a pivotal player in this rising configuration. The focus on Russia will account for the fact that while China's rise makes it potentially the most significant long-term threat, the current scale of Russia's arsenal and its strategic posture make it the most immediate existential threat to the United States and its allies, as well as a key potential spoiler in the U.S. strategic pivot to the Indo-Pacific. The research will proceed along three parallel tracks. The first track will analyze how the different motivations and capabilities of Russia and China to challenge the United States structures their incentives for strategic cooperation, and will review the key debates among Russian elites on these topics. The second part will analyze Russian elite perceptions of the opportunities and limits of cooperation with China in boosting each other's strategic capabilities and their employment strategies. The third track of the research will examine the role of arms control and confidence-building measures in the emerging trilateral context, with the United States facing two near-peer adversaries. This research will be conducted through a combined team effort of subject-matter experts on Russian, U.S., NATO, and Chinese strategic doctrines, capabilities, and behavior. The researchers will perform a rigorous analysis of the debates in the Russian literature, complementing and contextualizing this information through discussions with subject matter experts in Washington, USSTRATCOM, NATO Headquarters, SHAPE Headquarters, and in key European allies. The final report will provide a combined analytical assessment on the topic, and discuss the implications for the USN, DoD, and U.S. national security more broadly.N3/N5 - Plans & StrategyThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

    Implications of Two Peer Nuclear-Armed Adversaries on U.S. Deterrence Strategy and the Future of Arms Control Agreements

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    NPS NRP Executive SummaryThis research will examine the implications of the rise of two near-peer, nuclear-armed adversaries for the United States, with an emphasis on the Russian role as a pivotal player in this rising configuration. The focus on Russia will account for the fact that while China's rise makes it potentially the most significant long-term threat, the current scale of Russia's arsenal and its strategic posture make it the most immediate existential threat to the United States and its allies, as well as a key potential spoiler in the U.S. strategic pivot to the Indo-Pacific. The research will proceed along three parallel tracks. The first track will analyze how the different motivations and capabilities of Russia and China to challenge the United States structures their incentives for strategic cooperation, and will review the key debates among Russian elites on these topics. The second part will analyze Russian elite perceptions of the opportunities and limits of cooperation with China in boosting each other's strategic capabilities and their employment strategies. The third track of the research will examine the role of arms control and confidence-building measures in the emerging trilateral context, with the United States facing two near-peer adversaries. This research will be conducted through a combined team effort of subject-matter experts on Russian, U.S., NATO, and Chinese strategic doctrines, capabilities, and behavior. The researchers will perform a rigorous analysis of the debates in the Russian literature, complementing and contextualizing this information through discussions with subject matter experts in Washington, USSTRATCOM, NATO Headquarters, SHAPE Headquarters, and in key European allies. The final report will provide a combined analytical assessment on the topic, and discuss the implications for the USN, DoD, and U.S. national security more broadly.N3/N5 - Plans & StrategyThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

    Implications of Two Peer Nuclear-Armed Adversaries on U.S. Deterrence Strategy and the Future of Arms Control Agreements

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    NPS NRP Project PosterThis research will examine the implications of the rise of two near-peer, nuclear-armed adversaries for the United States, with an emphasis on the Russian role as a pivotal player in this rising configuration. The focus on Russia will account for the fact that while China's rise makes it potentially the most significant long-term threat, the current scale of Russia's arsenal and its strategic posture make it the most immediate existential threat to the United States and its allies, as well as a key potential spoiler in the U.S. strategic pivot to the Indo-Pacific. The research will proceed along three parallel tracks. The first track will analyze how the different motivations and capabilities of Russia and China to challenge the United States structures their incentives for strategic cooperation, and will review the key debates among Russian elites on these topics. The second part will analyze Russian elite perceptions of the opportunities and limits of cooperation with China in boosting each other's strategic capabilities and their employment strategies. The third track of the research will examine the role of arms control and confidence-building measures in the emerging trilateral context, with the United States facing two near-peer adversaries. This research will be conducted through a combined team effort of subject-matter experts on Russian, U.S., NATO, and Chinese strategic doctrines, capabilities, and behavior. The researchers will perform a rigorous analysis of the debates in the Russian literature, complementing and contextualizing this information through discussions with subject matter experts in Washington, USSTRATCOM, NATO Headquarters, SHAPE Headquarters, and in key European allies. The final report will provide a combined analytical assessment on the topic, and discuss the implications for the USN, DoD, and U.S. national security more broadly.N3/N5 - Plans & StrategyThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

    Development of bright fluorescent quadracyclic adenine analogues: TDDFT-calculation supported rational design

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    Fluorescent base analogues (FBAs) comprise a family of increasingly important molecules for the investigation of nucleic acid structure and dynamics. We recently reported the quantum chemical calculation supported development of four microenvironment sensitive analogues of the quadracyclic adenine (qA) scaffold, the qANs, with highly promising absorptive and fluorescence properties that were very well predicted by TDDFT calculations. Herein, we report on the efficient synthesis, experimental and theoretical characterization of nine novel quadracyclic adenine derivatives. The brightest derivative, 2-CNqA, displays a 13-fold increased brightness (epsilon Phi(F) = 4500) compared with the parent compound qA and has the additional benefit of being a virtually microenvironment-insensitive fluorophore, making it a suitable candidate for nucleic acid incorporation and use in quantitative FRET and anisotropy experiments. TDDFT calculations, conducted on the nine novel qAs a posteriori, successfully describe the relative fluorescence quantum yield and brightness of all qA derivatives. This observation suggests that the TDDFT-based rational design strategy may be employed for the development of bright fluorophores built up from a common scaffold to reduce the otherwise costly and time-consuming screening process usually required to obtain useful and bright FBAs

    The Antennae Galaxies (NGC 4038/4039) Revisited: ACS and NICMOS Observations of a Prototypical Merger

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    The ACS and NICMOS have been used to obtain new HST images of NGC 4038/4039 ("The Antennae"). These new observations allow us to better differentiate compact star clusters from individual stars, based on both size and color. We use this ability to extend the cluster luminosity function by approximately two magnitudes over our previous WFPC2 results, and find that it continues as a single power law, dN/dL propto L^alpha with alpha=-2.13+/-0.07, down to the observational limit of Mv~-7. Similarly, the mass function is a single power law dN/dM propto M^beta with beta=-2.10+/-0.20 for clusters with ages t<3x10^8 yr, corresponding to lower mass limits that range from 10^4 to 10^5 Msun, depending on the age range of the subsample. Hence the power law indices for the luminosity and mass functions are essentially the same. The luminosity function for intermediate-age clusters (i.e., ~100-300 Myr old objects found in the loops, tails, and outer areas) shows no bend or turnover down to Mv~-6, consistent with relaxation-driven cluster disruption models which predict the turnover should not be observed until Mv~-4. An analysis of individual ~0.5-kpc sized areas over diverse environments shows good agreement between values of alpha and beta, similar to the results for the total population of clusters in the system. Several of the areas studied show evidence for age gradients, with somewhat older clusters appearing to have triggered the formation of younger clusters. The area around Knot B is a particularly interesting example, with an ~10-50 Myr old cluster of estimated mass ~10^6 Msun having apparently triggered the formation of several younger, more massive (up to 5x10^6 Msun) clusters along a dust lane.Comment: 84 pages, 9 tables, 31 figures; ApJ accepte

    Continuous recruitment of naive T cells contributes to heterogeneity of antiviral CD8 T cells during persistent infection

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    Numerous microbes establish persistent infections, accompanied by antigen-specific CD8 T cell activation. Pathogen-specific T cells in chronically infected hosts are often phenotypically and functionally variable, as well as distinct from T cells responding to nonpersistent infections; this phenotypic heterogeneity has been attributed to an ongoing reencounter with antigen. Paradoxically, maintenance of memory CD8 T cells to acutely resolved infections is antigen independent, whereas there is a dependence on antigen for T cell survival in chronically infected hosts. Using two chronic viral infections, we demonstrate that new naive antigen-specific CD8 T cells are primed after the acute phase of infection. These newly recruited T cells are phenotypically distinct from those primed earlier. Long-lived antiviral CD8 T cells are defective in self-renewal, and lack of thymic output results in the decline of virus-specific CD8 T cells, indicating that newly generated T cells preserve antiviral CD8 T cell populations during chronic infection. These findings reveal a novel role for antigen in maintaining virus-specific CD8 T cells during persistent infection and provide insight toward understanding T cell differentiation in chronic infection

    Special topic: The association between pulse ingredients and canine dilated cardiomyopathy: addressing the knowledge gaps before establishing causation.

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    In July 2018, the Food and Drug Administration warned about a possible relationship between dilated cardiomyopathy (DCM) in dogs and the consumption of dog food formulated with potatoes and pulse ingredients. This issue may impede utilization of pulse ingredients in dog food or consideration of alternative proteins. Pulse ingredients have been used in the pet food industry for over 2 decades and represent a valuable source of protein to compliment animal-based ingredients. Moreover, individual ingredients used in commercial foods do not represent the final nutrient concentration of the complete diet. Thus, nutritionists formulating dog food must balance complementary ingredients to fulfill the animal's nutrient needs in the final diet. There are multiple factors that should be considered, including differences in nutrient digestibility and overall bioavailability, the fermentability and quantity of fiber, and interactions among food constituents that can increase the risk of DCM development. Taurine is a dispensable amino acid that has been linked to DCM in dogs. As such, adequate supply of taurine and/or precursors for taurine synthesis plays an important role in preventing DCM. However, requirements of amino acids in dogs are not well investigated and are presented in total dietary content basis which does not account for bioavailability or digestibility. Similarly, any nutrient (e.g., soluble and fermentable fiber) or physiological condition (e.g., size of the dog, sex, and age) that increases the requirement for taurine will also augment the possibility for DCM development. Dog food formulators should have a deep knowledge of processing methodologies and nutrient interactions beyond meeting the Association of American Feed Control Officials nutrient profiles and should not carelessly follow unsubstantiated market trends. Vegetable ingredients, including pulses, are nutritious and can be used in combination with complementary ingredients to meet the nutritional needs of the dog

    Differential Cross Sections and Cross-Section Ratios for the Electron-Impact Excitation of the Neon 2p⁵3s Configuration

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    Electron-impact differential cross-section measurements for the excitation of the 2p53s configuration of Ne are reported. The Ne cross sections are obtained using experimental differential cross sections for the electron-impact excitation of the n = 2 levels of atomic hydrogen [Khakoo et al., Phys. Rev. A 61, 012701-1 (1999)], and existing experimental helium differential cross-section measurements, as calibration standards. These calibration measurements were made using the method of gas mixtures (Ne and H followed by Ne and He), in which the gas beam profiles of the mixed gases are found to be the same within our experimental errors. We also present results from calculations of these differential cross sections using the R-matrix and unitarized first-order many-body theory, the distorted-wave Born approximation, and relativistic distorted-wave methods. Comparison with available experimental differential cross sections and differential cross-section ratios is also presented

    The SLUGGS Survey: Calcium Triplet-based Spectroscopic Metallicities for Over 900 Globular Clusters

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    Although the colour distribution of globular clusters in massive galaxies is well known to be bimodal, the spectroscopic metallicity distribution has been measured in only a few galaxies. After redefining the calcium triplet index-metallicity relation, we use our relation to derive the metallicity of 903 globular clusters in 11 early-type galaxies. This is the largest sample of spectroscopic globular cluster metallicities yet assembled. We compare these metallicities with those derived from Lick indices finding good agreement. In 6 of the 8 galaxies with sufficient numbers of high quality spectra we find bimodality in the spectroscopic metallicity distribution. Our results imply that most massive early-type galaxies have bimodal metallicity, as well as colour, distributions. This bimodality suggests that most massive galaxies early-type galaxies experienced two periods of star formation.Comment: 23 pages, 13 figures. Accepted for publication in MNRAS. For more information about the SLUGGS Survey please see http://sluggs.swin.edu.a
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