Cointegration and Asymmetric Adjustment between Output and Unemployment: an Application to the U.S. Economy

This paper focuses on the properties of the adjustment between the real output and the unemployment rate for the U.S. economy in the period from 1975 to 2006. It starts by checking the order of integration of the two series and then tests for the presence of asymmetry in the Okun’s law relationship through a cyclical equation, a first differences equation and an ADL(p,q). Using the threshold cointegration approach this study also accounts for the possible existence of a long-run equilibrium relationship and it is ability to test for the asymmetric adjustment hypothesis. It is found that Okun’s coefficient ranges between -0.41 and -0.59, being the latter estimated by the cointegrating equation. Furthermore, the unemployment rate behaves differently along the business cycle and increases faster in recessions than it recovers in expansions. A long-run equilibrium relationship is established where adjustment is made asymmetrically. Positive deviations away from equilibrium are corrected slightly faster than negative ones. Our explanation concerns the higher speed of flows within the labor market during a recession than during an expansion which may also be related to the existence of nominal rigidities in the US economy that causes imperfectly flexible prices.Okun’s Law, Threshold Cointegration, Asymmetric Adjustment, Monte Carlo Simulations, U.S. Economy

Multiple UAV teams for multiple tasks

In a search and prosecute mission, multiple heterogeneous unmanned aerial vehicles UAVs that carry different resources need to perform the classify, prosecute and battle damage assessment (BDA) tasks on targets sequentially. Depending on the target resource requirement, it may be necessary to deploy a coalition of UAVs to perform the action. In this paper, we propose coalition formation algorithms that have low computational overhead to determine coalitions for the prosecute and the BDA tasks. We also develop a simultaneous strike mechanism based on Dubins curves for the UAVs to prosecute the target simultaneously. Monte-Carlo simulation results are presented to show how the algorithms work and the effect of increasing the number of BDA tasks on the mission performance. © 2009 IEEE

Activated carbon as a redox mediator: effect of AC surface chemistry and solution pH on dye reduction

Azo dyes have a wide application in food, pharmaceutical, textile, leather, cosmetics and paper industries. These are the largest and most versatile classes of dyes used, but are recalcitrant to biodegradation and many are carcinogenic or cytotoxic. Their removal is a major concern when treating dye-containing wastewaters. Under anaerobic conditions, they are non-specifically reduced, a fortuitous but often slow process. Acceleration can be achieved by using electron-shuttling compounds that speed up the reaction, acting as redox mediators. Activated carbon (AC) has been shown as a feasible redox mediator and adsorbent material. In this study, the surface chemistry of a commercial AC (AC0) was selectively modified, without changing significantly its textural properties, by means of chemical oxidation with HNO3 (ACHNO3) (mild acidic surface properties) and thermal treatments under H2 (ACH2) or N2 (ACN2) flow (basic surface properties). Oxidation with 5% O2 (ACO2) ends not only in surface chemistry changes (acidic properties), but also in the textural properties. The effect of modified AC on anaerobic chemical dye reduction was assayed with sulphide as a reducing agent at different pH values: 5, 7 and 9. Four dyes from different classes were tested: Acid Orange 7, Reactive Red 2, Mordant Yellow 10 and Direct Blue 71. Batch experiments with low amounts of AC (0.1 g.L-1) demonstrated an increase of the first-order reduction rate constants (~ 9-fold) for all the dyes tested as compared with assays without AC. The reduction of AO7 and MY10 was highly dependent on the pH, with optimum rates at pH 5 and 7, respectively. Higher rates of RR2 and DB71 reduction were obtained at pH 5. In general, an increase of the rates with increasing the pHpzc was observed, following the trend ACHNO3 < ACO2 < AC0 < ACN2 < ACH2. Comparing the rates of single dyes, MY10 was reduced at the highest rate (12 ± 1 d-1) and RR2 at the lowest (1.3 ± 0.1 d-1)

A contour-based approach to binary shape coding using a multiple grid chain code

This paper presents a contour-based approach to efficiently code binary shape information in the context of object-based video coding. This approach meets some of the most important requirements identified for the MPEG-4 standard, notably efficient coding and low delay. The proposed methods support both object-based lossless and quasi-lossless coding modes. For the cases where low delay is a primary requirement, a macroblock-based coding mode is proposed which can take advantage of inter-frame coding to improve the coding efficiency. The approach presented here relies on a grid different from that used for the pixels to represent the shape – the hexagonal grid – which simplifies the task of contour coding. Using this grid, an appraoch based on a differential chain code (DCC) is proposed for the lossless mode while, for the quasi-lossless case, an approach based on the multiple grid chain code (MGCC) principle is proposed. The MGCC combines both contour simplification and contour prediction to reduce the number of bits needed to code the shapes. Results for alpha plane coding of MPEG-4 video test sequences are presented in order to illustrate the performance of the several modes of operation, and a comparison is made with the shape-coding tool chosen by MPEG-4.Peer ReviewedPostprint (published version

Notes on fauna associated with an opportunistic artificial reef near cold-water corals

This short communication provides a sporadic insight on the importance of a hard three-dimensional structure for deepwater fish near CWC. Fish size and behaviour inside the structure and in the surrounding area are described. Additionally, a list of biofouling macroorganisms found on the structure after one year of deployment is presented

Tailoring carbon nanotubes to enhance their efficiency as electron shuttle on the biological removal of acid orange 10 under anaerobic conditions

Anaerobic treatments have been described for the biodegradation of pollutants. However, the reactions proceed slowly due to the recalcitrant nature of these compounds. Carbon nanomaterials (CNM) intermediate in, and favor, the electron transfer, accelerating the anaerobic reduction of pollutants, which act as final electron acceptors. In the present work, different carbon nanotubes (CNT) with modified surface chemistry, namely CNT oxidized with HNO3 (CNT_HNO3) and CNT doped with nitrogen in a ball milling process (CNT_N_MB) were prepared using commercial CNT as a starting material. The new CNM were tested as redox mediators (RM), 0.1 g L−1, in the biological reduction of the azo dye, Acid Orange 10 (AO10), with an anaerobic granular sludge, over 48 h of reaction. Methane production was also assessed to verify the microorganism’s activity and the CNM’s effect on the methanogenic activity. An improvement in the biological removal of AO10 occurred with all CNM (above 90%), when compared with the control without CNM (only 32.4 ± 0.3%). The best results were obtained with CNT_N_MB, which achieved 98.2 ± 0.1% biological AO10 removal, and an 11-fold reduction rate increase. In order to confer magnetic properties to the CNM, tailored CNT were impregnated with 2% of iron-samples: CNTThis study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE‐01‐0145‐ FEDER‐000004) funded by the European Regional Development Fund under the scope of Norte2020 ‐ Programa Operacional Regional do Norte, as well as FCT/MCTES trough national funds (PIDDAC) and Base Funding – UIDB/50020/20 of the Associate Laboratory LSRE‐LCM – funded by national funds rough FCT/MCTES (PIDDAC). Ana Rita Silva holds a Grant from FCT, reference SFRH/BD/131905/2017. Salomé. G.P. Soares acknowledges FCT funding under the Scientific Employment Stimulus ‐ Institutional Call CEECINST/00049/2018.info:eu-repo/semantics/publishedVersio