The Firm as a Community Explaining Asymmetric Behavior and Downward Rigidity of Wages

This paper models the firm as a community à la Akerlof (1980) to account for asymmetric behavior, and in particular, downward rigidity of wages. It is shown that, through social interaction among workers in the firm community, wage cuts can give rise to a large, discontinuous fall in labor productivity (known as “catastrophe”). Furthermore, this large fall in labor productivity will persist or display inertia (known as “hysteresis”) even if the wages are restored to the pre-cut level and beyond. Our catastrophe/hysteresis finding with respect to wage cuts can rationalize the downward rigidity of wage behavior, and is consistent with the interview evidence of fragile worker morale emphasized by Bewley (1999) and others in explaining why employers are sensitive to and refrain from cutting worker pay.Wage rigidity, Firm community, Catastrophe, Hysteresis

Receiprocity and Downward Wage Rigidity

The employment relationship is to a large extent characterized by incomplete contracts, in which workers have a considerable degree of discretion over the choice of their work effort. This discretion at work kicks in the potential importance of “gift exchange” or reciprocity between workers and employers in their employment relationship. Built on the seminal work of Akerlof (1980), this paper adopts a social norm approach to model reciprocity in labor markets and theoretically derives two versions of downward wage rigidity. The first version explains why employers may adopt a high wage policy far above the competitive level. This version is not a novel finding in the existing literature and is mainly served as a benchmark for later comparison in the current paper. Our main contribution lies in the second version in which not nly may employers adopt a high wage policy far above the competitive level, but one can also account for the asymmetric behavior of wages and explain why employers are hesitant about wage cuts in the presence of negative shocks. We argue that this second and stronger version of downward wage rigidity has moved the efficiency wage theory a step forward.Reciprocity, Downward Wage Rigidity, Social Norm, Efficiency Wage

Investigating worn surfaces of nanoscale TiAlN/VN multilayer coating using FIB and TEM

TiAlN/VN multilayer coatings exhibit excellent dry sliding wear resistance and low friction coefficient, believed to be associated with the formation of tribo-films comprising Magnéli phases such as V2O5. In order to investigate this hypothesis, dry sliding wear of TiAlN/VN coatings was undertaken against Al2O3. Focused ion beam was used to generate site-specific TEM specimens. A thin (2-20nm) tribo-film was observed at the worn surface, with occasional 'roll-like' wear debris (φ 5-40nm). Both were amorphous and contained the same Ti, Al and V ratio as the coating, but with the nitrogen largely replaced by oxygen. No evidence of Magnéli phases was found. © 2006 IOP Publishing Ltd

Singlet-triplet transitions in highly correlated nanowire quantum dots

We consider a quantum dot embedded in a three-dimensional nanowire with tunable aspect ratio a. A configuration interaction theory is developed to calculate the energy spectra of the finite 1D quantum dot systems charged with two electrons in the presence of magnetic fields B along the wire axis. Fruitful singlet-triplet transition behaviors are revealed and explained in terms of the competing exchange interaction, correlation interaction, and spin Zeeman energy. In the high aspect ratio regime, the singlet-triplet transitions are shown designable by tuning the parameters a and B. The transitions also manifest the highly correlated nature of long nanowire quantum dots.Comment: 4 pages, 4 figure

Maximizing the Total Resolution of Graphs

A major factor affecting the readability of a graph drawing is its resolution. In the graph drawing literature, the resolution of a drawing is either measured based on the angles formed by consecutive edges incident to a common node (angular resolution) or by the angles formed at edge crossings (crossing resolution). In this paper, we evaluate both by introducing the notion of "total resolution", that is, the minimum of the angular and crossing resolution. To the best of our knowledge, this is the first time where the problem of maximizing the total resolution of a drawing is studied. The main contribution of the paper consists of drawings of asymptotically optimal total resolution for complete graphs (circular drawings) and for complete bipartite graphs (2-layered drawings). In addition, we present and experimentally evaluate a force-directed based algorithm that constructs drawings of large total resolution

Word matching using single closed contours for indexing handwritten historical documents

Effective indexing is crucial for providing convenient access to scanned versions of large collections of historically valuable handwritten manuscripts. Since traditional handwriting recognizers based on optical character recognition (OCR) do not perform well on historical documents, recently a holistic word recognition approach has gained in popularity as an attractive and more straightforward solution (Lavrenko et al. in proc. document Image Analysis for Libraries (DIAL’04), pp. 278–287, 2004). Such techniques attempt to recognize words based on scalar and profile-based features extracted from whole word images. In this paper, we propose a new approach to holistic word recognition for historical handwritten manuscripts based on matching word contours instead of whole images or word profiles. The new method consists of robust extraction of closed word contours and the application of an elastic contour matching technique proposed originally for general shapes (Adamek and O’Connor in IEEE Trans Circuits Syst Video Technol 5:2004). We demonstrate that multiscale contour-based descriptors can effectively capture intrinsic word features avoiding any segmentation of words into smaller subunits. Our experiments show a recognition accuracy of 83%, which considerably exceeds the performance of other systems reported in the literature

Thin helium film on a glass substrate

We investigate by Monte Carlo simulations the structure, energetics and superfluid properties of thin helium-four films (up to four layers) on a glass substrate, at low temperature. The first adsorbed layer is found to be solid and "inert", i.e., atoms are localized and do not participate to quantum exchanges. Additional layers are liquid, with no clear layer separation above the second one. It is found that a single helium-three impurity resides on the outmost layer, not significantly further away from the substrate than helium-four atoms on the same layer.Comment: Six figures, submitted for publication to the Journal of Low Temperature Physic

Exogenous NG-hydroxy-l-arginine causes nitrite production in vascular smooth muscle cells in the absence of nitric oxide synthase activity

AbstractNitric oxide (NO) production from exogenous NG-hydroxy-l-arginine (OH-l-Arg) was investigated in rat aortic smooth muscle cells in culture by measuring nitrite accumulation in the culture medium. As well, the interaction between OH-l-Arg and l-arginine uptake via the y+ cationic amino acid transporter was studied. In cells without NO-synthase activity, OH-l-Arg (1–1000 μM) induced a dose-dependent nitrite production with a half-maximal effective concentration (EC50) of 18.0 ± 1.5 μM (n = 4–7). This nitrite accumulation was not inhibited by the NO-synthase inhibitor NG-nitro-l-arginine methyl ester, l-NAME (300 μM). In contrast, it was abolished by miconazole (100 μM), an inhibitor of cytochrome P450. Incubation of vascular smooth muscle cells with LPS (10 μgml) induced an l-name inhibited nitrite accumulation, but did not enhance the OH-l-Arg induced nitrite production. OH-l-Arg and other cationic amino acids, L-lysine and l-ornithine, competitively inhibited [3H]-l-arginine uptake m rat aortic smooth muscle cells, with inhibition constants of 195 ± 23 μM(n = 12), 260 ± 40 μM(n= 5) and 330 ± 10 μM(n = 5), respectively. These results show that OH-l-Arg is recognized by the cationic l-amino acid carrier present in vascular smooth muscle cells and can be oxidized to NO and nitrite in these cells in the absence of NO-synthase, probably by cytochrome P450 or by a reaction involving a cytochrome P450 byproduct

Lombardi Drawings of Graphs

We introduce the notion of Lombardi graph drawings, named after the American abstract artist Mark Lombardi. In these drawings, edges are represented as circular arcs rather than as line segments or polylines, and the vertices have perfect angular resolution: the edges are equally spaced around each vertex. We describe algorithms for finding Lombardi drawings of regular graphs, graphs of bounded degeneracy, and certain families of planar graphs.Comment: Expanded version of paper appearing in the 18th International Symposium on Graph Drawing (GD 2010). 13 pages, 7 figure