3,507 research outputs found

    Visual Culture Project: Confederate War Etchings: Searching for Arms by Adalbert Johann Volck

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    Adalbert Johann Volck’s 1861 sketch of Union soldiers, “Searching for Arms,” represents a substantial contribution to the narrative about gender relations during the American Civil War. This simple, small sketch offers the observer a window into the past. It is a collision of symbols and meaning—from gender to war to the household—all wrapped up in one image. This is a portrait sketch of a woman being invaded in her domestic, private sphere, revealing so much about gender relations during the time. The mistress herself seemed to embody a vast range of sentiments such as anger, fear, frailty, and strength, proving the tension in her role as a wife, a mother, and guardian of the home. This inner conflict is something that all women faced during this time as they strove to remain loyal to the cause for which their husbands fought

    The Raman Spectra of CH3CF3 and CCl2CF2

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    Because of the interest attached to ethane and ethane-like molecules in connection with the question of free rotation of the CX3 groups with respect to each other, it was considered that the Raman spectrum of CH3CF3 might yield additional information on this point. Inasmuch as the spectrum of the liquid can be conveniently photographed only at low temperatures (b.p. about -40°), the determination of the polarization of the scattered light would be experimentally very difficult and was not attempted. The fact that the frequencies associated with the CF3 group will be considerably different in magnitude from those of the CH3 group may, in the analysis, compensate for the lack of data on polarization. Only the results of the experiments are presented here; the assignment of the frequencies will be given when completed. The Raman spectrum of the ethylene-like molecule CCl2=CF2 was photographed at room temperature with the substance in the liquid state, and the observed shifts are presented here

    Minimal kernels of Dirac operators along maps

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    Let MM be a closed spin manifold and let NN be a closed manifold. For maps f ⁣:MNf\colon M\to N and Riemannian metrics gg on MM and hh on NN, we consider the Dirac operator Dg,hfD^f_{g,h} of the twisted Dirac bundle ΣMRfTN\Sigma M\otimes_{\mathbb{R}} f^*TN. To this Dirac operator one can associate an index in KOdim(M)(pt)KO^{-dim(M)}(pt). If MM is 22-dimensional, one gets a lower bound for the dimension of the kernel of Dg,hfD^f_{g,h} out of this index. We investigate the question whether this lower bound is obtained for generic tupels (f,g,h)(f,g,h)

    Volume and homology of one-cusped hyperbolic 3-manifolds

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    Let M be a complete, finite-volume, orientable hyperbolic manifold having exactly one cusp. If we assume that pi_1(M) has no subgroup isomorphic to a genus-2 surface group, and that either (a) H_1(M;Z_p) has dimension at least 5 for some prime p, or (b) H_1(M;Z_2) has dimension at least 4, and the subspace of H^2(M;Z_2) spanned by the image of the cup product has dimension at most 1, then vol M > 5.06 If we assume that H_1(M;Z_2) has dimension at least 7, and that the compact core of M does not contain a genus-2 closed incompressible surface, then vol M > 5.06.Comment: 31 pages. This version agrees with the published version of the paper, except that an error in the published abstract has been corrected. In particular, the result which applies to manifolds with mod 2 homology of dimension at least 7 is stronger and has a shorter proof than the corresponding result in version

    On the Validity and Applicability of Models of Negative Capacitance and Implications for MOS Applications

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    The observation of room temperature sub-60 mV/dec subthreshold slope (SS) in MOSFETs with ferroelectric (FE) layers in the gate stacks or in series with the gate has attracted much attention. Recently, we modeled this effect in the framework of a FE polarization switching model. However, there is a large amount of literature attributing this effect to a stabilization of quasi-static (QS) negative capacitance (NC) in the FE. The technological implications of a stabilized non-switching (NS) QSNC model vs a FE switching model are vastly different; the latter precluding applications to sub-60 mV/dec SS scaled CMOS due to speed limitations and power dissipated in switching. In this letter, we provide a thorough analysis assessing the foundations of models of QSNC, identifying which specific assumptions (ansatz) may be unlikely or unphysical, and analyzing their applicability. We show that it is not reasonable to expect QSNC for two separate capacitors connected in series (with a metal plate between dielectric (DE) and FE layers). We propose a model clarifying under which conditions a QS "apparent NC" for a FE layer in a FE-DE bi-layer stack may be observed, quantifying the requirements of strong interface polarization coupling in addition to capacitance matching. In this regime, our model suggests the FE layer does not behave as a NC layer, simply, the coupling leads to both the DE and FE behaving as high-k DE with similar permittivities. This may be useful for scaled EOT devices but does not lead to sub-60 mV/dec SS.Comment: Version published in Appl. Phys. Let

    Spectral and Dynamical Properties in Classes of Sparse Networks with Mesoscopic Inhomogeneities

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    We study structure, eigenvalue spectra and diffusion dynamics in a wide class of networks with subgraphs (modules) at mesoscopic scale. The networks are grown within the model with three parameters controlling the number of modules, their internal structure as scale-free and correlated subgraphs, and the topology of connecting network. Within the exhaustive spectral analysis for both the adjacency matrix and the normalized Laplacian matrix we identify the spectral properties which characterize the mesoscopic structure of sparse cyclic graphs and trees. The minimally connected nodes, clustering, and the average connectivity affect the central part of the spectrum. The number of distinct modules leads to an extra peak at the lower part of the Laplacian spectrum in cyclic graphs. Such a peak does not occur in the case of topologically distinct tree-subgraphs connected on a tree. Whereas the associated eigenvectors remain localized on the subgraphs both in trees and cyclic graphs. We also find a characteristic pattern of periodic localization along the chains on the tree for the eigenvector components associated with the largest eigenvalue equal 2 of the Laplacian. We corroborate the results with simulations of the random walk on several types of networks. Our results for the distribution of return-time of the walk to the origin (autocorrelator) agree well with recent analytical solution for trees, and it appear to be independent on their mesoscopic and global structure. For the cyclic graphs we find new results with twice larger stretching exponent of the tail of the distribution, which is virtually independent on the size of cycles. The modularity and clustering contribute to a power-law decay at short return times

    The political economy of financing children's rights through extractive industries in the Philippines

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    The surging investments in the extractive industries (EI) that began in the 1980s, as well as the commodity boom between 2002 and 2011, have increased the significance of the sector in national economic development. This paper takes the Philippines as a case study and provides a detailed analysis of two key aspects of mining governance: first, the political challenges in realizing a more positive role for EI in social development, particularly in promoting children´s rights and children´s welfare, and second, the political economy dynamics that might underpin the creation of a welfare regime able to sustain social investments for children. The findings of this paper suggest that in the Philippine context, where the expansion of the EI sector is contested in the public domain, the link between mining governance and the promotion and protection of children´s rights is not necessarily straightforward. Yet equally, the resurgence of high prices and the continuing interest of foreign investment in EI means that there is now a political opportunity for relevant stakeholders to make a compelling argument for the need to ring-fence mineral rents for social investments in children and young people. To do so would require a strong pro-welfare policy coalition committed to channelling mineral wealth towards social investment and willing to craft a political consensus through negotiations between local and national elites, donor agencies, civil society organizations and affected local communities. Importantly, the state must also wrestle with multinational capital, large Filipino-owned companies and small-scale miners in the process of negotiating reforms. Ultimately, the state must seize this opportunity to take a more active role in laying the foundations of a mining governance framework, bargain with key stakeholders to reach agreement on EI-funded welfare and set out rights-based approaches to development. This paper builds on a selective qualitative data collection from a variety of printed sources, including donor agency reports, government documents, NGO reports, newspaper archives, and interviews available online. It further builds on a short fieldwork period in Manila, in late August 2013, where key sources from civil society, academia, the extractive industry, the donor community and stakeholders were interviewed

    The diameter of the set of boundary slopes of a knot

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    Let K be a tame knot with irreducible exterior M(K) in a closed, connected, orientable 3--manifold Sigma such that pi_1(Sigma) is cyclic. If infinity is not a strict boundary slope, then the diameter of the set of strict boundary slopes of K, denoted d_K, is a numerical invariant of K. We show that either (i) d_K >= 2 or (ii) K is a generalized iterated torus knot. The proof combines results from Culler and Shalen [Comment. Math. Helv. 74 (1999) 530-547] with a result about the effect of cabling on boundary slopes.Comment: This is the version published by Algebraic & Geometric Topology on 29 August 200

    More Torsion in the Homology of the Matching Complex

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    A matching on a set XX is a collection of pairwise disjoint subsets of XX of size two. Using computers, we analyze the integral homology of the matching complex MnM_n, which is the simplicial complex of matchings on the set {1,>...,n}\{1, >..., n\}. The main result is the detection of elements of order pp in the homology for p{5,7,11,13}p \in \{5,7,11,13\}. Specifically, we show that there are elements of order 5 in the homology of MnM_n for n18n \ge 18 and for n14,16n \in {14,16}. The only previously known value was n=14n = 14, and in this particular case we have a new computer-free proof. Moreover, we show that there are elements of order 7 in the homology of MnM_n for all odd nn between 23 and 41 and for n=30n=30. In addition, there are elements of order 11 in the homology of M47M_{47} and elements of order 13 in the homology of M62M_{62}. Finally, we compute the ranks of the Sylow 3- and 5-subgroups of the torsion part of Hd(Mn;Z)H_d(M_n;Z) for 13n1613 \le n \le 16; a complete description of the homology already exists for n12n \le 12. To prove the results, we use a representation-theoretic approach, examining subcomplexes of the chain complex of MnM_n obtained by letting certain groups act on the chain complex.Comment: 35 pages, 10 figure
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