Examples of finite free complexes of small rank and small homology

This work concerns finite free complexes over commutative noetherian rings, in particular over group algebras of elementary abelian groups. The main contribution is the construction of complexes such that the total rank of their underlying free modules, or the total length of their homology, is less than predicted by various conjectures in the theory of transformation groups and in local algebra.Comment: 13 pages. Version 2 is a significant revision of the first one. This paper will appear in Acta Mathematic

Exact summation of vertex corrections to the penetration depth in d-wave superconductors

A variety of experiments suggest that in the cuprates, the low-energy superconducting quasiparticles undergo forward scattering from extended impurity potentials. We argue that when such potentials dominate the scattering, the penetration depth may be computed in a simple zero-angle scattering approximation (ZSA), in which the vertex corrections to the Meissner effect may be summed exactly. We find a remarkably simple relationship between the normal fluid density and the quasiparticle density of states of the disordered system which holds for every realization of the disorder. We expect this result to be relevant to the $ab$-plane penetration depth in high-purity single crystals of underdoped YBCO.Comment: 4 pages, submitted to PR

Allocating resources fairly among group members: The medium of exchange matters

All organized groups face the fundamental problem of how to allocate resources fairly. Managers often confront this challenge when deciding whether to reward individual or team performance. Building upon recent research that demonstrates the unique norms invoked by the resource of money, we propose that what individuals' judge to be a fair allocation principle among group members systematically varies as a function of whether the resource being distributed is money versus other resources that are allocated within organizations. We review prior research examining contextual variables influencing allocation preferences and attempt to identify the different characteristics of money as a resource that might influence conceptions of fairness. In light of the existing research, we argue that an egalitarian allocation principle will be understood to be less fair when the norms of the market are invoked by the distribution of a resource that is a medium of exchange (e.g., money) rather than an in-kind good (e.g. food). We conclude by discussing the implications of identifying the unique properties of money for a wide set of literatures. This novel perspective on the role the allocation medium plays in how groups allocate resources fairly will be of interest to scholars of justice

Lim Ulrich sequences and Boij-S\"{o}derberg cones

This paper extends the results of Boij, Eisenbud, Erman, Schreyer, and S\"oderberg on the structure of Betti cones of finitely generated graded modules and finite free complexes over polynomial rings, to all finitely generated graded rings admitting linear Noether normalizations. The key new input is the existence of lim Ulrich sequences of graded modules over such rings.Comment: 26 page

Quantifying signals with power-law correlations: A comparative study of detrended fluctuation analysis and detrended moving average techniques

Detrended fluctuation analysis (DFA) and detrended moving average (DMA) are two scaling analysis methods designed to quantify correlations in noisy non-stationary signals. We systematically study the performance of different variants of the DMA method when applied to artificially generated long-range power-law correlated signals with an {\it a-priori} known scaling exponent $\alpha_{0}$ and compare them with the DFA method. We find that the scaling results obtained from different variants of the DMA method strongly depend on the type of the moving average filter. Further, we investigate the optimal scaling regime where the DFA and DMA methods accurately quantify the scaling exponent $\alpha_{0}$, and how this regime depends on the correlations in the signal. Finally, we develop a three-dimensional representation to determine how the stability of the scaling curves obtained from the DFA and DMA methods depends on the scale of analysis, the order of detrending, and the order of the moving average we use, as well as on the type of correlations in the signal.Comment: 15 pages, 16 figure

Adipocyte-derived endotrophin promotes malignant tumor progression

Adipocytes represent a major cell type in the mammary tumor microenvironment and are important for tumor growth. Collagen VI (COL6) is highly expressed in adipose tissue, upregulated in the obese state, and enriched in breast cancer lesions and is a stimulator of mammary tumor growth. Here, we have described a cleavage product of the COL6??3 chain, endotrophin (ETP), which serves as the major mediator of the COL6-mediated tumor effects. ETP augmented fibrosis, angiogenesis, and inflammation through recruitment of macrophages and endothelial cells. Moreover, ETP expression was associated with aggressive mammary tumor growth and high metastatic growth. These effects were partially mediated through enhanced TGF-?? signaling, which contributes to tissue fibrosis and epithelial-mesenchymal transition (EMT) of tumor cells. Our results highlight the crucial role of ETP as an obesity-associated factor that promotes tumor growth in the context of adipocyte interactions with tumor and stromal cells.open302

On the existence of star products on quotient spaces of linear Hamiltonian torus actions

We discuss BFV deformation quantization of singular symplectic quotient spaces in the special case of linear Hamiltonian torus actions. In particular, we show that the Koszul complex on the moment map of an effective linear Hamiltonian torus action is acyclic. We rephrase the nonpositivity condition of Arms, Gotay and Jennings for linear Hamiltonian torus actions. It follows that reduced spaces of such actions admit continuous star products.Comment: 9 pages, 4 figures, uses psfra

Thermodynamics and Kinetics of the Carbonyl process for the Refining of Nickel

The discovery by Langer and Mond in 1889 of the reaction of carbon monoxide at atmospheric pressure with active nickel at 315-353K to form gaseous Ni(C0)4 and its ready reversibility at higher temperatures paved the way for the development of the carbonyl refining process for nickel. Subsequently, to improve the kinetics, a high pressure process was developed for the carbonyl refining of Ni at somewhat higher temperatures. The carbonyl process makes it possible to produce nickel of very high purity and extr-emely fine size. This paper describes the thermodynamics and kinetics of the formation of nickel carbonyl from pure nickel and its alloys, its vapour phase transport and its decomposition.. The thermodynamic analysis includes const-ruction of Ellingham diagrams, pressure-temperature rela-tionships, partial pressuretemperature relationships and productivity function-temperature-pressure relationships for the various carbonyls. The kinetics of Ni(CO)4 forma-tion and decomposition has been analyzed based on the information available in the literature

Up and Out: Journalism, Social Media, and Historical Sensibility

Much of the modern theorizing about journalism and communication attained its robustness due to a powerful convergence of distinct middle-range scholarly findings that emerged primarily in the 1970s and 1980s. In the present day, when we turn our analytical gaze to the relationship between journalism and social media, we thus need to strike a delicate balance between conducting new qualitative research, re-conceptualizing and re-interrogating the classic conclusions of political communication scholarship, and linking these two aspects of research together. However, we might also wish to extend our analytical gaze “out,” interrogating the movement of journalistic technology across history, as well as “up,” looking at how journalism fits within larger structural explanations regarding the shape of political life