Aerial Remote Sensing in Agriculture: A Practical Approach to Area Coverage and Path Planning for Fleets of Mini Aerial Robots

In this paper, a system that allows applying precision agriculture techniques is described. The application is based on the deployment of a team of unmanned aerial vehicles that are able to take georeferenced pictures in order to create a full map by applying mosaicking procedures for postprocessing. The main contribution of this work is practical experimentation with an integrated tool. Contributions in different fields are also reported. Among them is a new one-phase automatic task partitioning manager, which is based on negotiation among the aerial vehicles, considering their state and capabilities. Once the individual tasks are assigned, an optimal path planning algorithm is in charge of determining the best path for each vehicle to follow. Also, a robust flight control based on the use of a control law that improves the maneuverability of the quadrotors has been designed. A set of field tests was performed in order to analyze all the capabilities of the system, from task negotiations to final performance. These experiments also allowed testing control robustness under different weather conditions.

In vivo zippering of inner and outer mitochondrial membranes by a stable translocation intermediate

It was previously assumed that the import of cytoplasmically synthesized precursor proteins into mitochondria occurs through a single structure spanning both outer and inner membranes at contact sites. Based on recent findings, however, the two membranes appear to contain independent translocation elements that reversibly cooperate during protein import. This feature makes it difficult to generate a means of isolating a fully integrated and functional translocation complex. To study these independent translocases in vitro and in vivo, we have constructed a chimeric protein consisting of an N-terminal authentic mitochondrial precursor (delta1-pyrroline-5-carboxylate dehydrogenase) linked, through glutathione S-transferase, to IgG binding domains derived from staphylococcal protein A. This construct becomes trapped en route to the matrix, spanning both outer and inner membranes in such a way that the entire signal-less delta1-pyrroline-5-carboxylate dehydrogenase moiety reaches the matrix, while only the folded protein A domain remains outside. During in vivo import of this precursor, outer and inner membranes of yeast mitochondria become progressively “zippered” together, forming long stretches of close contact. Using this novel intermediate, the outer and inner mitochondrial membrane channels, which normally interact only transiently, can be tightly joined (both in vitro and in vivo), forming a stable association. This suggests a method for isolating the functional translocation complex as a single entity.

Limited surface exposure of Borrelia burgdorferi outer surface lipoproteins.

We used novel immunofluorescence strategies to demonstrate that outer surface proteins (Osps) A, B and C of Borrelia burgdorferi have limited surface exposure, finding that contradicts the prevailing viewpoint that these antigens are exclusively surface exposed. Light labeling was observed when antibodies to OspA or OspB were added to motile organisms, whereas intense fluorescence was observed when the same slides were methanol-fixed and reprobed. Modest labeling also was observed when spirochetes encapsulated in agarose beads (gel microdroplets) were incubated with antibodies to these same two antigens. This contrasted with the intense fluorescence observed when encapsulated spirochetes were probed in the presence of 0.06% Triton X-100, which selectively removed outer membranes. Proteinase K (PK) treatment of encapsulated spirochetes abrogated surface labeling. However, PK-treated spirochetes fluoresced intensely after incubation with antibodies to OspA or OspB in the presence of detergent, confirming the existence of large amounts of subsurface Osp antigens. Modest surface labeling once again was detected when PK-treated spirochetes were reprobed after overnight incubation, a result consistent with the existence of a postulated secretory apparatus that shuttles lipoproteins to the borrelial surface. Last, experiments with the OspC-expressing B. burgdorferi strain 297 revealed that this antigen was barely detectable on spirochetal surfaces even though it was a major constituent of isolated outer mem- branes. We propose a model of B. burgdorferi molecular architecture that helps to explain spirochetal persistence during chronic Lyme disease.

Bioactive compounds and physical and chemical characteristics of mini tomatoes: influence of postharvest treatments

Tomatoes are among the most cultivated and used vegetables in the world. They are very succeptible to post harvest losses due to high perishability, therefore the use of postharvest treatments may contribute to conservation of this fruit, however the treatments might affect significantly physico-chemical, sensory and nutritional characteristics of tomatoes. Given the perishability of tomato and the economic importance of small tomato fruits, the purpose of the present study was to determine the effect of gamma radiation, carnauba coating and 1-MCP treatments on tomato fruit quality during storage. The study may be divided into two parts. In the first, mini tomatoes cv. Sweet Grape were harvested at breaker stage, divided into 4 grous and treated with gamma radiation (0.6 kGy), carnauba coating (1 L 1000 kg-1) and 1-MCP (500 nL L-1) and then stored at 25±2°C for 30 days with a control group of tomatoes. In the seconnd part, tomatoes harvested at light-red stage were submitted to the same treatments and storage period. Every 6 days tomatoes were evaluated for color modifications, fruit firmness, souble and total pectin (only for light-red tomatoes), mass loss, titratable acidity (TA), soluble solids (SS), SS/TA ratio, carotenoids profile, formation of lycopene isomers, total phenolic compounds, ascorbic acid and antioxidant capacity. For tomatoes harvested at breaker stage and submitted to the treatments the results showed mass loss was delaying mainly by carnauba wax, and to a lesser extend by 1-MCP. Fruit firmness were better retained for 1-MCP treated fruits and carnauba treatment showed a transient effect in preserving fruit firmness. SS/TA of tomatoes treated with gamma radiation and carnauba presented no differences from control values, and were lower with the application of 1-MCP. Color was negatively affected by 1-MCP and earlier changed (6th day) when gamma radiation was applied. In relation to bioactive compounds of tomatoes harvest at breaker stage, results indicated gamma radiation and 1-MCP decreased the final content of lycopene and produced more (Z)-isomers of lycopene. Gamma radiation also induced a decreased in ?-carotene and an increased in phenolic compounds by the end of storage period. 1-MCP treatment promoted a slow down increase in ascorbic acid content during storage. Antioxidant capacity of the hydrophilic fraction was not dramatically affected by treatments and the lipophilic fraction was lower, especially for 1-MCP fruits. In addition, contents of ?-carotene, lycopene, (Z)-isomers of lycopene, ascorbic acid and antioxidant capacity increased during the period of storage while contents of lutein and phenolic compounds tended to decrease. Regarding tomatoes harvest at light-red stage, the most effective treatments for delaying fruit firmness and mass loss was carnauba and 1-MCP, while gamma radiation was the treatment with higher mass loss and the less fruit firmness, which could be associated with the higher solubilization of pectins promoted by radiation treatment. Color (L* and Hue) was mainly affected by 1-MCP treatment which delayed color development, however, by the end of storage, the values were not different from the other treatments. SS/TA ratio was lower for fruits treated with 1-MCP and TA was not so dramatically affected by treatments. Furthermore, mini tomatoes harvested at light-red stage, demonstrated irradiation induced changes in the final content of lycopene, increasing it, and formed less (13Z)-lycopene, while 1-MCP and carnauba coating slow down the increase in lycopene and slown down the decrease of ascorbic acid and phenolic compounds. Antioxidant capacity of lipophilic fraction was not affected by treatments and the hydrophilic fraction was lower for irradiated fruits only on day 0 as well as phenolic compounds. In the other days, no differences among treatments were observed for hydrophilic antioxidant capacity. Considering the results, the best combination of SS and TA and fruit preservation for mini tomatoes harvest at breaker stage was promoted by carnauba coating, which seems to be the treatment that causes fewer changes in bioactive compounds of breaker tomatoes. However, when mini tomatoes were harvested at light-red stage, SS/TA ratio and color were better and, to preserve the quality of these fruits, besides carnauba coating, 1-MCP also could be indicated

Solenogastres from the eastern coast of North America / by Harold Heath.

v.45:no.2 (1918)

Concording EU trade and production data over time. National Bank of Belgium Working Paper No. 239, December 2012

This paper provides concordance procedures for product-level trade and production data in the EU and examines the implications of changing product classifications on measured product adding and dropping at Belgian firms. Using the algorithms developed by Pierce and Schott (2012a, 2012b), the paper develops concordance procedures that allow researchers to trace changes in coding systems over time and to translate product-level production and trade data into a common classification that is consistent both within a single year and over time. Separate procedures are created for the eightdigit Combined Nomenclature system used to classify international trade activities at the product level within the European Union as well as for the eight-digit Prodcom categories used to classify products in European domestic production data. The paper further highlights important differences in coverage between the Prodcom and Combined Nomenclature classifications which need to be taken into account when generating combined domestic production and international trade data at the product level. The use of consistent product codes over time results in less product adding and dropping at continuing firms in the Belgian export and production data.

Fiscal policy, banks and the financial crisis. National Bank of Belgium Working Paper No. 234, October 2012

This paper studies the effectiveness of Euro Area (EA) fiscal policy, during the recent financial crisis, using an estimated New Keynesian model with a bank. A key dimension of policy in the crisis was massive government support for banks—that dimension has so far received little attention in the macroeconomics literature. We use the estimated model to analyze the effects of bank asset losses, of government support for banks, and other fiscal stimulus measures, in the EA. Our results suggest that support for banks had a stabilizing effect on EA output, consumption and investment. Increased government purchases helped to stabilize output, but crowded out consumption. Higher transfers to households had a positive impact on private consumption, but a negligible effect on output and investment. Banking shocks and increased government spending explain half of the rise in the public debt/GDP ratio since the onset of the crisis.

The fragility of two monetary regimes: The European Monetary System and the Eurozone. National Bank of Belgium Working Paper No. 243, October 2013

The purpose of these working papers is to promote the circulation of research results (Research Series) and analytical studies (Documents Series) made within the National Bank of Belgium or presented by external economists in seminars, conferences and conventions organised by the Bank. The aim is therefore to provide a platform for discussion. The opinions expressed are strictly those of the authors and do not necessarily reflect the views of the National Bank of Belgium.

Why firms avoid cutting wages: Survey evidence from European firms. National Bank of Belgium Working Paper No. 251, December 2013

The rarity with which firms reduce nominal wages has been frequently observed, even in the face of considerable negative economic shocks. This paper uses a unique survey of fourteen European countries to ask firms directly about the incidence of wage cuts and to assess the relevance of a range of potential reasons for why they avoid cutting wages. Concerns about the retention of productive staff and a lowering of morale and effort were reported as key reasons for downward wage rigidity across all countries and firm types. Restrictions created by collective bargaining were found to be an important consideration for firms in euro area countries but were one of the lowest ranked obstacles in non-euro area countries. The paper examines how firm characteristics and collective bargaining institutions affect the relevance of each of the common explanations put forward for the infrequency of wage cuts.

The distribution of debt across euro area countries : The role of individual characteristics, institutions and credit conditions. National Bank of Belgium Working Paper No. 252, December 2013

The aim of this paper is twofold. First, we present an up-to-date assessment of the differences across euro area countries in the distributions of various measures of debt conditional on household characteristics. We consider three different outcomes: the probability of holding debt, the amount of debt held and, in the case of secured debt, the interest rate paid on the main mortgage. Second, we examine the role of legal and economic institutions in accounting for these differences. We use data from the first wave of a new survey of household finances, the Household Finance and Consumption Survey, to achieve these aims. We find that the patterns of secured and unsecured debt outcomes vary markedly across countries. Among all the institutions considered, the length of asset repossession periods best accounts for the features of the distribution of secured debt. In countries with longer repossession periods, the fraction of people who borrow is smaller, the youngest group of households borrow lower amounts (conditional on borrowing), and the mortgage interest rates paid by low-income households are higher. Regulatory loan-to-value ratios, the taxation of mortgages and the prevalence of interest-only or fixed-rate mortgages deliver less robust results.