144 research outputs found

    Spatiotemporal instability of a confined capillary jet

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    Recent experimental studies on the instability appearance of capillary jets have revealed the capabilities of linear spatiotemporal instability analysis to predict the parametrical map where steady jetting or dripping takes place. In this work, we present an extensive analytical, numerical and experimental analysis of confined capillary jets extending previous studies. We propose an extended, accurate analytic model in the limit of low Reynolds flows, and introduce a numerical scheme to predict the system response when the liquid inertia is not negligible. Theoretical predictions show a remarkable accuracy with results from the extensive experimental exploration provided.Comment: Submitted to the Physical Review E (20-March-2008

    Statement of changes in equity

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    Since the new General Chart of Accounts was passed, the amount of financial information that is required to the corporations had increased. There have been two new financial statements too: Statement of Changes in Equity and Cash Flow Statement. We analyze the Statement of Changes in Equity on this paper, and the changes result of the new financial statement. Also, the statement of changes in equity has two new accounts: 8th group “Expenditure of Equity” and 9th group “Income of Equity”. The accounting rules for grants, donations and bequest had changed too, those are regulated by the Statement of Registration and Assessment 18th. On the same way, the rules for financial instruments or securities has changed too, those are regulated by the Statement of Registration and Assessment 9th. The information that must been provided by those accounts, now is not limited to the annual report. The main goal is an improvement of financial information provided by corporations.Subvenciones; Instrumentos Financieros; Estado de Cambios de Patrimonio Neto; Nuevo Plan General Contable

    We have to go back: A Historic IP Attribution Service for Network Measurement

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    Researchers and practitioners often face the issue of having to attribute anIP address to an organization. For current data this is comparably easy, usingservices like whois or other databases. Similarly, for historic data, severalentities like the RIPE NCC provide websites that provide access to historicrecords. For large-scale network measurement work, though, researchers oftenhave to attribute millions of addresses. For current data, Team Cymru providesa bulk whois service which allows bulk address attribution. However, at thetime of writing, there is no service available that allows historic bulkattribution of IP addresses. Hence, in this paper, we introduce and evaluateour `Back-to-the-Future whois' service, allowing historic bulk attribution ofIP addresses on a daily granularity based on CAIDA Routeviews aggregates. Weprovide this service to the community for free, and also share ourimplementation so researchers can run instances themselves.<br

    One-dimensional dynamics of nearly unstable axisymmetric liquid bridges

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    A general one-dimensional model is considered that describes the dynamics of slender, axisymmetric, noncylindrical liquid bridges between two equal disks. Such model depends on two adjustable parameters and includes as particular cases the standard Lee and Cosserat models. For slender liquid bridges, the model provides sufficiently accurate results and involves much easier and faster calculations than the full three-dimensional model. In particular, viscous effects are easily accounted for. The one-dimensional model is used to derive a simple weakly nonlinear description of the dynamics near the instability limit. Small perturbations of marginal instability conditions are also considered that account for volume perturbations, nonequality of the supporting disks, and axial gravity. The analysis shows that the dynamics breaks the reflection symmetry on the midplane between the supporting disks. The weakly nonlinear evolution of the amplitude of the perturbation is given by a Duffing equation, whose coefficients are calculated in terms of the slenderness as a part of the analysis and exhibit a weak dependence on the adjustable parameters of the one-dimensional model. The amplitude equation is used to make quantitative predictions of both the (first stage of) breakage for unstable configurations and the (slow) dynamics for stable configurations

    El estado de cambios en el patrimonio neto.

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    Since the General Chart of Accounts had been changed, the number of financial statements has gone up. Now, it is required more financial information to the companies on its annual accounts. These new financial statements are Statement of Changes in Equity and Cash Flow Statement. Instead, the Statement of Changes in Equity summarizes the items which are not classified as liabilities, financial instruments and its fluctuations. Moreover, when this new accounting statement was passed, the control about accounting has increased. Bearing in mind, the creation of 8th and 9th financial accounts group; contra-accounts are the statements which composed the 13rd subgroup. Financial accounts which belong to the 13rd subgroup are summarized on the Statement of Changes in Equity. The main goal is an improvement of financial information provided by corporations

    Heterozygosity-fitness correlations and inbreeding depression in two critically endangered mammals

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    The relation among inbreeding, heterozygosity, and fitness has been studied primarily among outbred populations, and little is known about these phenomena in endangered populations. Most researchers conclude that the relation between coefficient of inbreeding estimated from pedigrees and fitness traits (inbreeding-fitness correlations) better reflects inbreeding depression than the relation between marker heterozygosity and fitness traits (heterozygosity-fitness correlations). However, it has been suggested recently that heterozygosity-fitness correlations should only be expected when inbreeding generates extensive identity disequilibrium (correlations in heterozygosity and homozygosity across loci throughout the genome). We tested this hypothesis in Mohor gazelle (Gazella dama mhorr) and Iberian lynx (Lynx pardinus). For Mohor gazelle, we calculated the inbreeding coefficient and measured heterozygosity at 17 microsatellite loci. For Iberian lynx, we measured heterozygosity at 36 microsatellite loci. In both species we estimated semen quality, a phenotypic trait directly related to fitness that is controlled by many loci and is affected by inbreeding depression. Both species showed evidence of extensive identity disequilibrium, and in both species heterozygosity was associated with semen quality. In the Iberian lynx the low proportion of normal sperm associated with low levels of heterozygosity was so extreme that it is likely to limit the fertility of males. In Mohor gazelle, although heterozygosity was associated with semen quality, inbreeding coefficient was not. This result suggests that when coefficient of inbreeding is calculated on the basis of a genealogy that begins after a long history of inbreeding, the coefficient of inbreeding fails to capture previous demographic information because it is a poor estimator of accumulated individual inbreeding. We conclude that among highly endangered species with extensive identity disequilibrium, examination of heterozygosity-fitness correlations may be an effective way to detect inbreeding depression, whereas inbreeding-fitness correlations may be poor indicators of inbreeding depression if the pedigree does not accurately reflect the history of inbreeding.Peer Reviewe

    Increasing and decreasing droplets velocity in micro channels

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    This paper deals with a specific aspect of non miscible liquid-liquid systems in microfluidic. For Chemical Engineering applications, the main constraints of functioning lies in the droplets velocity and frequency. Furthermore, the material used and the composition of the fluids is often imposed by the chemistry of the system (material resistance, fluids composition) and there is no possibility of adding other compound (surfactants for example). A technique under evaluation is presented: by using secondary channels and pumps, it is possible to increase or decrease at will the droplets velocity after they have been generated. Some experimental results are presented and discussed, including the possible limits of such an approach

    Air entrainment through free-surface cusps

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    In many industrial processes, such as pouring a liquid or coating a rotating cylinder, air bubbles are entrapped inside the liquid. We propose a novel mechanism for this phenomenon, based on the instability of cusp singularities that generically form on free surfaces. The air being drawn into the narrow space inside the cusp destroys its stationary shape when the walls of the cusp come too close. Instead, a sheet emanates from the cusp's tip, through which air is entrained. Our analytical theory of this instability is confirmed by experimental observation and quantitative comparison with numerical simulations of the flow equations
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