Temporary Employment, Job Flows and Productivity: A Tale of two Reforms

We investigate the effects of two reforms of temporary employment using panel data on Italian firms. We exploit variation in their implementation across regions and sectors for identification. We find that the reform of apprenticeship contracts increased job turnover and induced the substitution of external staff with firms’ apprentices, with an overall productivity-enhancing effect. The reform of fixed-term contracts instead did not produce the intended results: it induced a substitution of temporary employees in favour of permanent ones and reduced capital intensity, generating productivity losses. We estimate substitution elasticities across types of temporary contracts that are consistent with these interpretations.employment contracts, productivity, institutional changes

Flexible Employment, Job Flows and Labour Productivity

In this paper we provide evidence on the effects of temporary employment on job flows, labour productivity and investment. As a source of identification, we exploit reforms in the legislation of fixed-term and apprenticeships contracts whose implementation varied over regions and industries. Results indicate that the reform of apprenticeship contracts has increased the turnover of workers and has induced capital-labor substitution in favour of labour, with an overall productivity-enhancing effect. The reform of fixed-term contracts instead does not seem to have had the intended results and may have made the use of these contracts more costly rather than less costly. Ineffectiveness of the reform may also depend on firms substituting across different types of labour: we estimate elasticities of substitution that are consistent with this interpretation.employment contracts, productivity, institutional changes

MPEG-7 Requirements to Highlight and Order Description Items

This document proposes some additional requirements to the MPEG-7 Requirements Document [2]. We think that some very important MPEG-7 requirements should deal with the concepts of (1) highlighting description items (e.g. images, sounds, events, objects etc.) which are most relevant to characterize a multimedia document and (2) of information ordering. In other words, due to a possible high amount of description items, an entity who will create descriptions of multimedia (MM) documents, according to MPEG-7 standard specifications (i.e. a description provider), shall highlight the items most representative for the kind of document being described in order to facilitate user needs (such as queries, navigation etc.). Besides, we consider the need of providing users with ordering mechanisms a very relevant issue to MPEG-7. Such ordering mechanisms can be derived by combining descriptor values (e.g., a set of key – frames ordered on the basis a color descriptor or a set of sounds ordered by means of their loudness descriptor). However the possible large variety of descriptors forming a description could consequently lead to a high number of ordering criteria for every description item of a subset of these items. Therefore we propose that the description provider should also highlight a reduced set of descriptors allowing to order some elements (e.g., key frames, events etc.) of a certain description in a proper manner for the MM document being described. The document is organized as follows: we explain the motivation behind our proposals in Section 2 and we present the new requirements in Section 3

Earnings Instability and Tenure

This paper develops a tractable empirical approach to estimate the effect of on-the-job tenure on the permanent and transitory variance of earnings. The model is also used to evaluate the earnings instability associated with fixed-term contract (short-tenure contracts) in Italy. Our results indicate that each year of tenure on the job reduces earnings instability on average by 15%. Workers on a fixed-term contract on average have an earnings instability 10% higher than workers on a permanent contract. Workers who spend their entire working life on fixed-term contracts can expect an earnings instability twice as high.earnings instability, earnings dynamics, tenure, temporary contracts, minimum distance estimation.

Optimization of Heliostat Fields for Solar Tower Systems

In this work, a geometrical model is used to evaluate the sun radiation reflected from the heliostats toward the aim point on the tower top, by taking into account the shading and blocking between neighboring heliostats. This results in an analytical expression for the heliostats efficiency, which can provide very useful informations for the optimization of the heliostat field. In particular, we obtain a very simple and exact expression of the maximal energy collectable by the solar field and present effective strategies to reach such maximum.2012-09-11Perpignan, Morocco, Marrakech; 2012Proceedings of the 18th International SolarPaces Symposiu

Load Imbalance and Caching Performance of Sharded Systems

Sharding is a method for allocating data items to nodes of a distributed caching or storage system based on the result of a hash function computed on the item’s identifier. It is ubiquitously used in key-value stores, CDNs and many other applications. Despite considerable work that has focused on the design and implementation of such systems, there is limited understanding of their performance in realistic operational conditions from a theoretical standpoint. In this paper we fill this gap by providing a thorough modeling of sharded caching systems, focusing particularly on load balancing and caching performance aspects. Our analysis provides important insights that can be applied to optimize the design and configuration of sharded caching systems

High Speed Visualizations of oil Jet Lubrication for Aero-engine Gearboxes☆

Abstract Augmenting gearing systems efficiency is a key issue in developing innovative aero-engines with low specific fuel consumption. The transmission system directly affects the engine overall efficiency, therefore it is essential maximizing its performance. In high speed applications fluid-dynamic losses become predominant and are directly connected to the lubrication method. Oil jet systems are generally used in order to achieve a proper cooling and lubrication of tooth surface. A novel rotating test rig was exploited for investigating oil jet lubrication by means of high speed visualizations. An oil jet impinging radially on a single spur gear was generated by a spray-bar, assessing which parameters affect the oil jet behavior

Imaging struma ovarii by means of 124I-Na PET/CT

Struma ovarii is a rare form of ovary tumour defined as the presence of ectopic thyroid tissue in the ovarian structures. Itusually presents with a benign course, although in some cases carcinoma or other malignant tumours can be found in the context of the ectopic tissue. Herein we report the case of a youngpatient affected by struma ovarii visualized by means of 124I-NaPET/CT. Thanks to the excellent target-to-background ratio ofthe tracer and the high resolution of the method, we could well identify the presence of some minimal tumour at the level of theleft ovary. To our knowledge, this is the first report of its kind

Hierarchical Content Stores in High-speed ICN Routers: Emulation and Prototype Implementation

Recent work motivates the design of Information-centric rou-ters that make use of hierarchies of memory to jointly scale in the size and speed of content stores. The present paper advances this understanding by (i) instantiating a general purpose two-layer packet-level caching system, (ii) investigating the solution design space via emulation, and (iii) introducing a proof-of-concept prototype. The emulation-based study reveals insights about the broad design space, the expected impact of workload, and gains due to multi-threaded execution. The full-blown system prototype experimentally confirms that, by exploiting both DRAM and SSD memory technologies, ICN routers can sustain cache operations in excess of 10Gbps running on off-the-shelf hardware