Aggregate Flows Research Articles

Aid for trade, labor market flexibility with implication for Korea

PurposeThe existing literature on aid for trade (AfT) tends to support the effectiveness of AfT in improving trade capacities and enhancing the export performance of recipient countries. While aid directed at trade-related infrastructure (e.g. ports and roads) is reported to drive the overall effect of AfT, the increasing importance of labor market flexibility and informal labor in export environment has been largely overlooked. The purpose of this paper is to test two hypotheses regarding the relationship between labor market flexibility, exports and AfT. First, flexible labor regulation promotes exports by reducing adjustment costs related to the export process. Second, for informal labor-intensive export sectors, AfT effectiveness may be compromised by the contraction of the informal sector due to labor deregulation as it deteriorates comparative advantage that supports recipients’ export competitiveness.Design/methodology/approachSince first introduced by Tinbergen (1962), the gravity model has been widely used to analyze bilateral trade, and its usefulness has been verified in several prominent empirical studies (e.g. Anderson and van Wincoop, 2003; Helpman et al., 2008). However, despite the empirically successful framework of the gravity model, the standard gravity equation may not be appropriate for estimating the effect of AfT in the paper. The main interest lies in whether aggregate AfT flows enhance the export “performance” of individual recipients, that is, whether they improve the recipients’ total exports rather than their bilateral exports. For this purpose, the authors took aggregated approach to the gravity model from Anderson and van Wincoop (2003).FindingsThe findings suggest that while both AfT and labor market flexibility are positively associated with higher export levels, the export-promoting effect of AfT is marginally reduced by the contraction of informal workforce. These findings, however, only hold for export sectors that heavily rely on informal labor force, that is, primary commodities and resource/labor-intensive goods. The authors also find that these effects are stronger in low-income countries, indicating that the AfT initiative has been effective where it is needed the most.Originality/valueThis paper is the first attempt to analyze the relationship between AfT and exports with consideration of labor market flexibility. Using the data for 85 recipient countries, the authors test the following hypotheses. First, labor market flexibility promotes exports by reducing adjustment costs related to the exporting process. Second, the contraction of the informal sector due to labor deregulation deteriorates developing countries’ comparative advantage in certain export sectors. Hence, while both AfT and labor market flexibility are expected to enhance the export volume of developing countries, the loss from weaker comparative advantage in a form of smaller informal labor force can exceed the gains from AfT in certain sectors.

Volatile capital flows and economic growth: The role of banking supervision

In this paper, we examine the links among banking supervision, the volatility of financial flows, and economic growth. In particular, we explore whether banking regulation mitigates the adverse effects of capital flows volatility on economic growth. Using cross-country data over four decades, we find that banking supervision promotes economic growth by dampening the negative impact of volatile capital flows. The findings hold for both aggregate capital flows and its various components, and for both its net and gross counterparts, while they are also robust for various indicators of regulatory policies. The results support the argument that bank regulatory policy rules designed to ensure financial stability are beneficial to long-run economic growth.

Biocompatibility and biomineralization assessment of mineral trioxide aggregate flow.

Evaluate, in vivo, the biocompatibility via subcutaneous inflammatory tissue response and mineralization ability of the new MTA Flow compared to MTA Angelus and ProRoot MTA. Forty male Wistar rats were assigned and received subcutaneous polyethylene tube implants containing the test materials and a control group with empty tube (n = 10 animals/group). After days 7, 15, 30, and 60, the animals were euthanized and the polyethylene tubes were removed with the surrounding tissues. Inflammatory infiltrate and thickness of the fibrous capsule were histologically evaluated. Mineralization was analyzed by Von Kossa staining and under polarized light. Data were analyzed via Kruskal-Wallis and Dunn's test with a significance level of 5%. MTA Angelus induced the mildest reaction after 7 (P > .05) and 15days (P < .05) followed by MTA Flow, both cements achieving mild inflammatory reaction after 15days. ProRoot MTA induced a severe inflammation on day 7 and was reducing after day 15 (P > .05). No difference was observed after days 30 or 60 (P > .05). Von Kossa staining and birefringent structures were positive to all materials. At the end of the experiment, the novel MTA Flow showed biocompatibility and induced biomineralization in all time periods. The final consistence obtained in MTA Flow may facilitate several procedures, indicating that the MTA Flow has a promising application in endodontics.

Join and spilt TCP for SDN networks: Architecture, implementation, and evaluation

With the advent of SDN technologies, fine-granular steering and dynamic controlling of network flows can be possible. Such features can be appropriately utilized to enhance the network performance. In this paper, we present a composite system-level implementation framework for aggregation and splitting of TCP flows. Our framework is featured to work in an end-user agnostic manner that doesn’t involve intervention or modification from the end-user.While most existing works are focused either on aggregation-only or split-only frameworks, we propose a more practical ‘join-and-split’ working prototype using SDN. To the best of our knowledge, for the first time, we implement a composite join-and-split TCP architecture that uses efficient mechanisms to synchronize different join and split network points. We have used a ‘linked-ACK’ mechanism to preserve the end-to-end semantics of flows that are separated by the join and split network points. With extensive performance evaluation study, we show the improved performance achieved by our framework in both wired and wireless environments. We describe the implementation of aggregation/splitting of TCP flows intuitively through state diagram. We are hopeful that this paper serves as system-level guide for the research community.

Aggregation of Markov flows I: theory.

A Markov flow is a stationary measure, with the associated flows and mean first passage times, for a continuous-time regular jump homogeneous semi-Markov process on a discrete state space. Nodes in the state space can be eliminated to produce a smaller Markov flow which is a factor of the original one. Some improvements to the elimination methods of Wales are given. The main contribution of the paper is to present an alternative, namely a method to aggregate groups of nodes to produce a factor. The method can be iterated to make hierarchical aggregation schemes. The potential benefits are efficient computation, including recomputation to take into account local changes, and insights into the macroscopic behaviour.This article is part of the theme issue 'Hilbert's sixth problem'.

Effect of Target Composition and Sputtering Deposition Parameters on the Functional Properties of Nitrogenized Ag-Permalloy Flexible Thin Films Deposited on Polymer Substrates.

We report the first results of functional properties of nitrogenized silver-permalloy thin films deposited on polyethylene terephthalic ester {PETE (C10H8O4)n} flexible substrates by magnetron sputtering. These new soft magnetic thin films have magnetization that is comparable to pure Ni81Fe19 permalloy films. Two target compositions (Ni76Fe19Ag5 and Ni72Fe18Ag10) were used to study the effect of compositional variation and sputtering parameters, including nitrogen flow rate on the phase evolution and surface properties. Aggregate flow rate and total pressure of Ar+N2 mixture was 60 sccm and 0.55 Pa, respectively. The distance between target and the substrate was kept at 100 mm, while using sputtering power from 100–130 W. Average film deposition rate was confirmed at around 2.05 nm/min for argon atmosphere and was reduced to 1.8 nm/min in reactive nitrogen atmosphere. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, vibrating sample magnetometer, and contact angle measurements were used to characterize the functional properties. Nano sized character of films was confirmed by XRD and SEM. It is found that the grain size was reduced by the formation of nitride phase, which in turns enhanced the magnetization and lowers the coercivity. Magnetic field coupling efficiency limit was determined from 1.6–2 GHz frequency limit. The results of comparable magnetic performance, lowest magnetic loss, and highest surface free energy, confirming that 15 sccm nitrogen flow rate at 115 W is optimal for producing Ag-doped permalloy flexible thin films having excellent magnetic field coupling efficiency.

Underwater Robotic Welding of Lap Joints with Sandwiched Reactive Multilayers: Thermal, Mechanical and Material Analysis

ABSTRACTUnderwater welding using reactive materials pre-deposited at the junction surfaces as a self-contained, in-situ ignitable heat source mitigates external power and gas supply requirements. Consequently, lending itself to robotic implementation eliminating the cost along with health and safety hazards of human welder-divers. This project reports on lap joining of aluminum sheets with sandwiched commercial reactive Ni-Al multilayers that are perforated to allow for melt fusion under compression upon ignition, in saline and deionized water as well as air for comparison. Finite-element thermal simulations are employed to study the resulting welding temperature field and melt conditions. Infrared pyrometry and thermocouple measurements during welding were used to validate the computational simulations. The lap joints are subjected to standard shear testing, and comparable compliance, strength and toughness values of the welds are assessed for underwater and dry joints. Scanning electron (SEM) of the weld sections reveal rapidly melting and solidifying microstructures of the parent metal, with minimal melt flow and perfusion of nickel aluminide aggregates from the reacted multilayers, and no signs of cavitation.

Fragmentation of biofilm-seeded bacterial aggregates in shear flow

We present a model for the force acting to fragment a biofilm-seeded microbial aggregate in shear flow, which we derive by coupling an existing model for the shape and orientation of a deforming ellipsoid with one for the surface force density on a solid ellipsoid. The model can be used to simulate the motion, shape, surface force density, and breakage of colloidal aggregates in shear flow. We apply the model to the case of exhaustive fragmentation of microbial aggregates in order to compute a post-fragmentation density function, indicating the likelihood of a fragmenting aggregate yielding daughter aggregates of a certain size.

Gatun Dam—megastructure of the Panama Canal

Abstract The kingpin structure of the American scheme to construct a ship canal across Panama in 1907–1914 was an earthen dam of unprecedented scale and scope at Gatun, to retain the aggregate flow of the Chagres River and its principal tributaries. Upon this structure alone, the entire plan rested, because it created the man-made lake rising 85 ft (25.9 m) above sea level, which allowed ships to cross the 550 ft (167.6 m) continental divide between the Atlantic and Pacific Oceans. Everything about Gatun Dam was enormous. Its dimensions were without precedent: a crest length of 8,200 ft (2,500 m) and a maximum width of 2,300 ft (701 m). With a height of 105 ft (32 m) above sea level, it stored sufficient water to maintain an operating pool covering 164 mi2 (425 km2). At its center was the most critical structure, a mass concrete spillway capable of passing flood flows of the unpredictable Chagres River. The biggest problem with the site was the underlying geology, which included two deepley incised paleo-channels. The massive embankments were placed over these paleo-channels, which were up to 258 ft (78.6 m) deep. The channel infill of the upper 50 ft (15.2 m) was of relatively low permeability, mostly sandy silts and clay. There were more pervious sands and gravel lying beneath these, which allowed deep seepage cutoffs to be precluded.

Estimating matching functions when recruiting intensity matters

ABSTRACTThe article estimates matching functions – the relationships between new hires, job vacancies and unemployment – using monthly time series data for Sweden. The data contain rich information on types of job vacancies which provides information on firms’ recruiting efforts. The analysis shows that the aggregate flow of new hires is well explained by an augmented version of a standard matching function that incorporates data on firms’ recruiting intensity.

Anomaly Detection and Attribution in Networks With Temporally Correlated Traffic

Anomaly detection in communication networks is the first step in the challenging task of securing a network, as anomalies may indicate suspicious behaviors, attacks, network malfunctions, or failures. In this paper, we address the problem of not only detecting the anomalous events but also of attributing the anomaly to the flows causing it. To this end, we develop a new statistical decision theoretic framework for temporally correlated traffic in networks via Markov chain modeling. We first formulate the optimal anomaly detection problem via the generalized likelihood ratio test (GLRT) for our composite model. This results in a combinatorial optimization problem which is prohibitively expensive. We then develop two low-complexity anomaly detection algorithms. The first is based on the cross entropy (CE) method, which detects anomalies as well as attributes anomalies to flows. The second algorithm performs anomaly detection via GLRT on the aggregated flows transformation - a compact low-dimensional representation of the raw traffic flows. The two algorithms complement each other and allow the network operator to first activate the flow aggregation algorithm in order to quickly detect anomalies in the system. Once an anomaly has been detected, the operator can further investigate which specific flows are anomalous by running the CE-based algorithm. We perform extensive performance evaluations and experiment our algorithms on synthetic and semi-synthetic data, as well as on real Internet traffic data obtained from the MAWI archive, and finally make recommendations regarding their usability.

A PATENTABILITY REQUIREMENT AND INDUSTRY-TARGETED R&amp;D

I introduce a minimum innovation size required for patents into a Schumpeterian growth model. We show that to satisfy the patentability requirement for minimum innovation size, each research and development (R&amp;D) firm targets only industries in which the incumbent's technology is of sufficient obsolescence. This is because the technological gap between innovator and incumbent is greater in industries using older technologies. Although the increase in minimum innovation size reduces the number of industries targeted for R&amp;D, it also increases the amount of R&amp;D investment directed at those targeted industries. Consequently, introducing a minimum innovation size has a nonmonotonic (or negative) effect on the aggregate flow of innovations. Further, by deriving the endogenous long-run distribution of innovation size, we show that an increase in minimum innovation size reduces the mean innovation size. This implies that even if the patent office only grants patents for superior innovations, it causes innovators to produce generally inferior-quality innovations.

LiteVisor: A Network Hypervisor to Support Flow Aggregation and Seamless Network Reconfiguration for VM Migration in Virtualized Software-Defined Networks

Network virtualization based on software-defined networking (SDN) has become a necessary technology to provide various services in cloud datacenters. Although many network hypervisors have been proposed to support SDN-based network virtualization, their forwarding techniques excessively consume the limited ternary contents addressable memory of OpenFlow-enabled switches. Moreover, they do not consider network reconfiguration after virtual machine migration. In this paper, we propose LiteVisor, that resolves the two problems mentioned above. It develops the Locator, Identifier, and Tenant sEparating (LITE) scheme. The LITE-based forwarding enables flow aggregation that reduces switch memory consumption. In addition, LiteVisor provides seamless network reconfiguration that does not require tenant controllers to be aware of virtual machine migration based on LITE. We evaluate LiteVisor in terms of the number of flow table entries and network reconfiguration time and compare it with OpenVirteX that is an open-source network hypervisor. The results show that the number of flow rules decreases by up to eight times compared with OpenVirteX in a fat-tree topology. We also demonstrate the seamless network reconfiguration of LiteVisor in the experiments and present the results of the reconfiguration time by the topology size and packet sending interval of hosts.

The Life-cycle Profile of Worker Flows in Europe

In this paper, we first provide a comprehensive account of the relationship between cross-country differences in aggregate employment and disaggregated differences in worker flows along the life cycle. To this end, we use survey micro-data for 31 European countries, and estimate the life-cycle profiles of transition probabilities across employment, unemployment and nonparticipation for each country. We develop a decomposition measuring the contribution of these transition probabilities to aggregate employment differences. We find substantial cross-country heterogeneity with respect to the role of worker flows out of each labor market state. Next, we relate this heterogeneity to cross-country differences in labor market institutions. Our analysis emphasizes age-dependent vs. age-independent labor market policies, and policies related to family formation, planning and dissolution. By going well beyond the study of differences of aggregate worker flows, we obtain a rich picture of the employment effects of labor market institutions.

Critically Important: The Heterogeneous Effect of Politics on Trade

There is strong empirical evidence showing that political relations have an impact on aggregate bilateral trade flows. In this paper, we show that the impact is heterogeneous across products, depending on product characteristics. Specifically, imported products used as intermediate inputs intensively may be more sensitive to adverse shocks. This is particularly relevant in the current context of increased international input linkages. We sketch a simple theoretical framework and test the mechanism in reduced-form. We implement a difference-in-differences approach with monthly trade flows and a novel dataset of diplomatic incidents. We find that a negative shock to political relations leads to a general decrease in trade flows, and that the response is larger for products in markets with low price gaps to alternative sourcing partners and high direct and indirect imported input use.

Market Potential and Global Growth over the Long Twentieth Century

We examine the evolution of market potential over the long twentieth century from 1900 to 2010. Theoretically, we exploit a structural gravity model to derive a closed-form solution for a widely-used measure of market potential. We are, thus, able to express market potential as a function of directly observable and easily estimable variables. This allows us to consistently compare our measure of market potential both in the cross-section and over time. Empirically, we collect a large data set on aggregate and bilateral trade flows as well as output for 51 countries. We find that market potential exhibits an upward trend across all regions of the world, in particular after World War II. The rise in market potential is also associated with a significant share of global income growth over that period.

Happily Ever After: Immigration, Natives’ Marriage, and Fertility

In this paper, we study the effects of immigration on natives' marriage, fertility, and family formation across US cities between 1910 and 1930. Instrumenting immigrants' location decision by interacting pre-existing ethnic settlements with aggregate migration flows, we find that immigration raised marriage rates, the probability of having children, and the propensity to leave the parental house for young native men and women. We show that these effects were driven by the large and positive impact of immigration on native men's employment and occupational standing, which increased the supply of marriageable men. We also explore alternative mechanisms − changes in sex ratios, natives' cultural responses, and displacement effects of immigrants on female employment − and provide evidence that none of them can account for a quantitatively relevant fraction of our results.

Study on the relationship between collision of blood flow and platelet aggregation using microchannel

Study on the relationship between collision of blood flow and platelet aggregation using microchannel

Adaptive Aggregation of Flow Records

This paper explores the problem of processing the immense volume of measurement data arising during network traffic monitoring. Due to the ever-increasing demands of current networks, observing accurate information about every single flow is virtually infeasible. In many cases the existing methods for the reduction of flow records are still not sufficient enough. Since the accurate knowledge of flows termed as "heavy-hitters" suffices to fulfill most of the monitoring purposes, we decided to aggregate the flow records pertaining to non-heavy-hitters. However, due to the ever-changing nature of traffic, their identification is a challenge. To overcome this challenge, our proposed approach - the adaptive aggregation of flow records - automatically adjusts its operation to the actual traffic load and to the monitoring requirements. Preliminary experiments in existing network topologies showed that adaptive aggregation efficiently reduces the number of flow records, while a significant proportion of traffic details is preserved.

A Flow Aggregation Method under Allowable Delay Limitation in SDN

A Flow Aggregation Method under Allowable Delay Limitation in SDN