Fast Separable Non-Local Means

We propose a simple and fast algorithm called PatchLift for computing distances between patches (contiguous block of samples) extracted from a given one-dimensional signal. PatchLift is based on the observation that the patch distances can be efficiently computed from a matrix that is derived from the one-dimensional signal using lifting; importantly, the number of operations required to compute the patch distances using this approach does not scale with the patch length. We next demonstrate how PatchLift can be used for patch-based denoising of images corrupted with Gaussian noise. In particular, we propose a separable formulation of the classical Non-Local Means (NLM) algorithm that can be implemented using PatchLift. We demonstrate that the PatchLift-based implementation of separable NLM is few orders faster than standard NLM, and is competitive with existing fast implementations of NLM. Moreover, its denoising performance is shown to be consistently superior to that of NLM and some of its variants, both in terms of PSNR/SSIM and visual quality

Critical properties and stability of stationary solutions in multi-transonic pseudo-Schwarzschild accretion

For inviscid, rotational accretion flows, both isothermal and polytropic, a simple dynamical systems analysis of the critical points has given a very accurate mathematical scheme to understand the nature of these points, for {\em any} pseudo-potential by which the flow may be driven on to a Schwarzschild black hole. This allows for a complete classification of the critical points for a wide range of flow parameters, and shows that the only possible critical points for this kind of flow are saddle points and centre-type points. A restrictive upper bound on the angular momentum of critical solutions has been established. A time-dependent perturbative study reveals that the form of the perturbation equation, for both isothermal and polytropic flows, is invariant under the choice of any particular pseudo-potential. Under generically true outer boundary conditions, the inviscid flow has been shown to be stable under an adiabatic and radially propagating perturbtion. The perturbation equation has also served the dual purpose of enabling an understanding of the acoustic geometry for inviscid and rotational flows

Finding the optimum activation energy in DNA breathing dynamics: A Simulated Annealing approach

We demonstrate how the stochastic global optimization scheme of Simulated Annealing can be used to evaluate optimum parameters in the problem of DNA breathing dynamics. The breathing dynamics is followed in accordance with the stochastic Gillespie scheme with the denaturation zones in double stranded DNA studied as a single molecule time series. Simulated Annealing is used to find the optimum value of the activation energy for which the equilibrium bubble size distribution matches with a given value. It is demonstrated that the method overcomes even large noise in the input surrogate data.Comment: 9 pages, 4 figures, iop article package include

Sharing the Risks of Bankruptcy: \u3ci\u3eTimbers\u3c/i\u3e, \u3ci\u3eAhlers\u3c/i\u3e, and Beyond

Bankruptcy policy appears to be in disarray. Recent decisions by the United States Supreme Court have only served to reinforce the uncertainties that mar the bankruptcy process. In United Savings Association of Texas v. Timbers of Inwood Forest Associates, Ltd., the Court held that an undersecured creditor was not entitled to interest on its collateral as compensation for the opportunity costs of delay caused by the bankruptcy process. Timbers thus supports the argument that secured creditors should be forced to share the burdens of bankruptcy with other claimants. Conversely, in Norwest Bank Worthington v. Ahlers, the Court held that the proposed contribution of future labor on the family farm could not trump the absolute priority rule that bars a debtor\u27s retention of an equity interest over the objections of senior creditors. Thus, Ahlers rejects the claim that secured creditors should be forced to share the burdens of bankruptcy through a liberalized contribution rule. Can these decisions be reconciled? And what light do they shed on the future of bankruptcy sharing? There are a number of ways to rationalize the results in Timbers and Ahlers through careful statutory and doctrinal analyses. The fact that this article does not address them does not belittle the value of careful allegiance to the Bankruptcy Code and prior case law in seeking to predict the future of bankruptcy law. Nevertheless, few would doubt that the Court could have written carefully reasoned opinions justifying the opposite result in each case. Thus, it seems probable that unacknowledged and unexpressed policy considerations may have influenced the Court. This article examines precisely what those policy goals are and what they imply for the future of federal bankruptcy. Part I of the article analyzes the traditional objectives of the bankruptcy process in terms of the techniques of contemporary legal analysis. This exercise is principally one of translation, the time-honored task of pouring old wine into new bottles. By attempting to recharacterize old truths in contemporary terms, I mean to clarify what those truths really mean. Thereafter, Part II sketches a theory that rationalizes the apparently conflicting objectives of bankruptcy law. The theory suggests that the Court\u27s decisions in Timbers and Ahlers are, in fact, entirely consistent and complementary. This approach thus provides a convenient benchmark for assessing how the burdens of bankruptcy ought best to be shared between various claimants of different classes

A Two Stage Investigation of the Determinants of Information Systems Outsourcing

Outsourcing has recently emerged as akey method of managing Information Systems especially since the report about Eastman Kodak and IBM\u27s outsourcing partnership in 1989 (Loh and Venkatraman, 1992a, 1992b). The importance of outsourcing is partially illustrated by the fact that there are myriad conflicting arguments both for and against outsourcing (Chaudhury et al, 1989, 1995; Gantz, 1990; Lacity and Hirschheim, 1993; Nam et al, 1995a, 1995b). Most outsourcing studies have focused on the investigation of the determinants of the decision to outsource by clients. Transaction cost economics (TCE) theory has recently been used in the study of the determinants of outsourcing (Lacity and Hirschheim, 1993; Nam et al, 1995a, 1995b). The theory of transaction cost economics (TCE) was originally formulated to address the make versus buy choice (Anderson and Coughlan, 1987; Erramilli and Rao, 1993) In TCE, Williamson (1989, 1987, 1981, 1979) proposed that firms should insource when they expect opportunistic behavior by the vendors. In particular when clients are locked-in with vendors, vendors\u27 opportunistic behavior will significantly impair the clients\u27 interests. This statement implies that attributes of existing relationships such as opportunism affect the firms\u27 subsequent make-or-buy decision with the incumbent vendors. However, most prior empirical research on TCE has treated each sourcing decision as an independent event (Masten, 1984; Walker and Walker, 1987, 1984) thereby disregarding the prior relationships that affect the subsequent sourcing decisions. Therefore, any outsourcing study must explicitly incorporate the role of prior ties in its analytical framework (Gulati, 1995). In the outsourcing context, it has been reported that very often clients continue their relationships with vendors. Also, many firms have to decide whether they should continue the outsourcing relationships with the vendors or not. Factors that affect continuation of the relationships are different from factors that affect the initial outsourcing behavior because client firms have locked-in relationships with vendors. According to Seabright et al (1992), and Levinthal et al (1988), prior relationships need to be investigated in order to study the subsequent relationships between clients and vendors. This study willfocus on i) the determinants of the outsourcing decisions and ii) the tendency to persist in the locked-in outsourcing relationship. We investigate the factors that determine outsourcing decisions in two stages. In the first stage, both insourcing and outsourcing firms are studied to investigate the determinants of make-or-buy decision. In the second stage, only outsourcing firms are considered in order to study the intention to continue with the relationship. Two dimensions are proposed in order to conceptualize the diverse types of outsourcing between clients and vendors (Nam et al, 1994a, 1994b). The first dimension is the extent of substitution by IS vendors and the second dimension is the strategic impact of IS applications. There are two types of strategic impact of IS applications: differentiation and cost reduction. The first dimension is proposed from the IS vendors\u27 point of view while the second dimension is proposed from the client firms\u27 point of view. Based on these two dimensions, four types of outsourcing relationships are proposed. These four types are support, reliance, alignment, and alliance. The support cell has a low extent of substitution and low strategic impact. This cell corresponds to the traditional IS vendors service. Vendorsare usually restricted to non-core IS activities and the size of contract is small. The reliance cell has a high extent of substitution and low strategic impact. The IBM and Kodak outsourcing example corresponds to this cell. In recent years, the trend ofoutsourcing has moved from the support cell to the reliance cell. The alignment cell has a low extent of substitution and high strategic impact. Examples in this cell are mostly IS consulting types of services. Even though vendors are not significantly involved with client firms\u27 IS operations, IS vendors significantly influence clients\u27 IS operations. The alliance cell has a high extent of substitution and high strategic impact. Outside vendors not only substitute in-house IS operations but also contribute to clients\u27 competitive advantages through provision of important IS functional activities. In the first stage, hypotheses are developed based on transaction and non-transaction cost factors with respect to the two proposed outsourcing dimensions. Threetransaction cost factors are studied as determinants of the two dimensions: asset specificity, uncertainty, potential number of vendors. Four non-transaction cost factors are also investigated. These four non-TCE factors are IT competency, IS influence, heterogeneity of information systems, and decision analysis effort. Multiple regressions are used to test hypotheses in the first stage. In the second stage, hypotheses are proposed based on prior relationships between clients and vendors in order to studythe determinants of the intention to continue with the outsourcing relationships. Prior relationships are represented by the four types of outsourcing relationships based on two dimensions of outsourcing, vendors performance in terms of client satisfaction, vendors\u27 opportunistic behavior and the length of prior relationships. Logistic regression is employed to test hypotheses in the second stage. Questionnaires were developed based on interviews with IS manager and pretested. Following a pretest, 800 questionnaires were sent to senior IS managers in the U.S. A follow-up letter was mailed to those who had not responded after about three weeks. In total 154 usable questionnaires were received representing a response rate of 19.25%. Out of 154, 93 respondedas outsourcing firms and 61 responded as insourcing firms

Development of Aluminium based Metal Matrix Composites

A detailed study on the processing of Al-metal matrix comp, cites with the reinforcement of different parti-culates such as SiC, TiN and Ti02 was carried out. The Al-SiC composite powder prepared through atomisation route is expected to limit the interfacial reaction bet-ween the matrix and the ceramic particulate and help in making customer tailored components by powder metallurgy route. An attempt to avoid the interfacial reaction of matrix and ceramic is investigated by impregnating the Al matrix with TiN particulates. Similarly, Al-Ti02.composite is investigated by new spray forming technique, where the interfacial reaction between Al and Ti02 is expected to form intermetallic compounds and improve the bonding and mechanical properties. The results of the present studies show that the Al based composites prepared through various techniques exhibits excellent mechanical, physical and tribological properties and could emerge as promising materials for defence, aerospace and other engineering applications

First time observation of latitudinal and vertical distribution of infra-red radiative flux using radiometer sonde over Indian Ocean during the INDOEX IFP-1999 and its comparison with other Indian stations

Latitudinal distribution of radiative flux at different layers has been measured for the first time over the Indian Ocean from 15°N to 20°S during intensive field phase of INDOEX 1999. Simultaneously measurements have been made over three Indian ground stations, viz. Delhi, Pune and Trivandrum. The basic feature of radiative flux over the Indian Ocean, Delhi, Pune and Trivandrum is similar, i.e. the radiative flux increases with altitude and reaches a maximum value at 15 km and after that the increasing rate slows down. The most striking feature of this observation is the existence of radiative flux between 12 and 15 km of height near the equator (1.75°N, 62.98°E) which may be due to the combined effect of partly cloudy sky, presence of aerosol and ozone. In addition, at 13.3°N, 60.5°E a similar feature has been observed at a height of 14–15 km, which may be due to the increment of ozone by 25 Dobson Unit (D.U.) during the onward journey since no aerosol was observed. During the return journey, at 12°S, 60.4°E global warming is also observed at a height of 13–15 km, which may also be due to the combined effect of partly cloudy sky and the presence of aerosol and increment of ozone