Regional variety and employment growth in Italian labour market areas: services versus manufacturing industries

This paper investigates the impact of regional sectoral diversity on regional employment growth in Italy over the period 1991-2001. Assuming that externalities may be stronger between industries selling similar products or sharing the same skills and technology (i.e. related industries), we analyze the role of different forms of sectoral variety at the Local Labour System (LLS) level. We consider variety both in terms of shared complementary competences that induce effective interactive learning and innovation, as well as a portfolio strategy to protect a region from external shocks in demand. Our results show strong evidence of a general beneficial effect of a diversified sectoral structure but suggest also the need to differentiate the analysis between manufacturing and services. In particular, overall local employment growth seems to be favoured by the presence of a higher variety of related service industries, while no role is played by related variety in manufacturing. When looking at diversity externalities between macro-aggregates, the service industry is affected by related variety in manufacturing, while no evidence of externalities is found from tertiary sectors to manufacturing

Experimental analysis and transient numerical simulation of a large diameter pulsating heat pipe in microgravity conditions

A multi-parametric transient numerical simulation of the start-up of a large diameter Pulsating Heat Pipe (PHP) specially designed for future experiments on the International Space Station (ISS) are compared to the results obtained during a parabolic flight campaign supported by the European Space Agency. Since the channel diameter is larger than the capillary limit in normal gravity, such a device behaves as a loop thermosyphon on ground and as a PHP in weightless conditions; therefore, the microgravity environment is mandatory for pulsating mode. Because of a short duration of microgravity during a parabolic flight, the data concerns only the transient start-up behavior of the device. One of the most comprehensive models in the literature, namely the in-house 1-D transient code CASCO (French acronym for Code Avancé de Simulation du Caloduc Oscillant: Advanced PHP Simulation Code in English), has been configured in terms of geometry, topology, material properties and thermal boundary conditions to model the experimental device. The comparison between numerical and experimental results is performed simultaneously on the temporal evolution of multiple parameters: tube wall temperature, pressure and, wherever possible, velocity of liquid plugs, their length and temperature distribution within them. The simulation results agree with the experiment for different input powers. Temperatures are predicted with a maximum deviation of 7%. Pressure variation trend is qualitatively captured as well as the liquid plug velocity, length and temperature distribution. The model also shows the ability of capturing the instant when the fluid pressure begins to oscillate after the heat load is supplied, which is a fundamental information for the correct design of the engineering model that will be tested on the ISS. We also reveal the existence of strong liquid temperature gradients near the ends of liquid plugs both experimentally and by simulation. Finally, a theoretical prediction of the stable functioning of a large diameter PHP in microgravity is given. Results show that the system provided with an input power of 185W should be able to reach the steady state after 1min and maintain a stable operation from then on

Student perceptions of interpersonal justice, engagement, agency and anger: a longitudinal study for reciprocal effects

Based on the premise that classroom interactions unfold through a complex series of circular influences between teacher and students, the aim of this longitudinal study was to test a reciprocal effects model connecting students’ perceptions of interpersonal justice, on the one hand, and student engagement, agency and anger, on the other. Self-report measures of interpersonal justice, student engagement, agency and anger were collected from 454 Year Nine students from Northern Italy in a 3-wave longitudinal research design. Structural equation modelling with latent variables indicated that interpersonal justice in wave 1 had a negative effect on both student agency and anger in wave 2, while interpersonal justice in wave 2 only negatively predicted student anger in wave 3. With respect to the reciprocal effects, student engagement in wave 2 was found to positively predict interpersonal justice in wave 3, while a negative effect close to statistical significance was observed from student agency in wave 2 to interpersonal justice in wave 3. These results are discussed in terms of their implications for teacher practice, as they emphasize that (a) the two main facets of student participation, namely engagement and agency, are differently interconnected with the learning environment, and (b) the perception of being treated fairly is important to the point that its deficiency triggers a persistent feeling of anger in students

CORRELATION BETWEEN CHRONIC MUCOSAL TRAUMA AND ORAL CANCER: A CASE REPORT AND REVIEW OF THE LITERATURE

Abstract – Objective: Squamous cell carcinoma is the most common malignancy in the oral cavity representing the 90% of all oral malignancies that affect oral cavity. Primary risk factors associated with oral cancer are alcohol and tobacco consumption. However, other emerging risk factors have been proposed in Literature, including chronic trauma of the oral mucosa related to dental prostheses and incongruous restorations. Therefore, the aim of this study was to review the literature on the correlation between oral carcinoma and chronic irritative trauma, with the help of a case report and with focus on clinical features and differential diagnosis. Materials and Methods: A literature search on MEDLINE, PubMed, ScienceDirect, Cochrane Database of Systematic Reviews and Wiley InterScience was performed, using the following words: Oral Cancer, chronic Trauma and Denture Trauma in various combinations. Results: The review produced 1356 results, but only 8 articles met the inclusion criteria and were involved in the review. No association has been proven between chronic mucosal trauma and oral cancer. Carcinoma has been shown to develop more frequently in trauma regions, particularly in the tongue. As for the data on the gender and age of affected patients, it emerges that most of the greatest incidence occurs around the sixth and seventh decade of life and men are more affected than women. Conclusions: Due to the heterogeneity of the different studies and the strong presence of other factors such as smoking and alcohol, the role of trauma in carcinogenesis is unclear. Further molecular, epidemiological and case-control studies are needed to define this correlation. It is advisable to carry out more restricted checks in patients at risk with dental prostheses

Experimental analysis of the thermal energy storage potential of a phase change material embedded in additively manufactured lattice structures

Recent literature introduced novel additively manufactured porous metallic structures designed to deliver enhancement of the thermal conductivity of organic phase change materials. Among these, so-called lattice structures are of particular interest for application in lightweight components. Originally investigated for their attractive mass-specific mechanical properties, these geometries were recently proposed, in alternative to metallic foams, as a conductive matrix of phase change materials. However, the geometrical parameters of a lattice structure differ from the ones of a metallic foam and no established data exist in the literature about the influence of the lattice cell geometry on the transient heat transfer enhancement of a phase change material. This work presents an experimental comparison of the thermal behaviour of a composite based on an n-Octadecane paraffin wax embedded in four different aluminium lattices with varying unit cell topology (f2ccz, bcc, bccz, f2bcc), but showing the same cell size, aspect ratio and strut diameter. It is noticed that the unit cell topology affects the transient thermal behaviour beyond its direct effect on the cell porosity. To address this, a specific thermal performance parameter is identified. The sample based on the f2ccz topology represents the best candidate. The influence of orientation with respect to gravity on the heat transfer is also investigated. While the samples show relatively low porosity, ranging from 70.7% to 83.4%, the wide pore diameters lead to a high impact of melt convection on the thermal behaviour of most samples. Up to 28% wall temperature variation is evidenced for different heating orientations

Heat transfer delay method for the fluid velocity evaluation in a multi-turn pulsating heat pipe

A multi-turn closed loop pulsating heat pipe made of aluminium is tested in vertical bottom heated mode and different condenser temperatures with the aim of providing quantitative information regarding its flow dynamics through a novel post-processing technique on the local wall-to-fluid heat flux, evaluated within the adiabatic section. The studied device is made of an annealed aluminium tube (inner/outer diameter: 3/5 mm), folded in 14 turns and partially filled with methanol (volumetric filling ratio: 50%). The aluminium channels are coated with a high-emissivity opaque paint, thus allowing thermographic measurements on the outer wall by means of a high-resolution medium wave infrared camera. The proposed method, named Heat Transfer Delay Method, is validated by means of a dedicated experimental approach. Then, the acquired time-space temperature maps are used as input data for the inverse heat conduction problem resolution approach to estimate the local convective heat flux locally exchanged at the inner wall-fluid interface. The resulting wall-to-fluid heat fluxes are then post- processed by applying the Heat Transfer Delay Method to the oscillatory and circulatory flow modes. The average fluid velocity is assessed at varying working conditions during the circulatory flow, finding values up to 0.77 m/s and 0.3 m/s for condenser temperature equal to 20 ◦C and 10 ◦ C, respectivel

On the use of shape memory alloys for deployable passive heat radiators in space satellites

The present work presents a multifunctional structure for space engineering application part of the TOPDESS project, funded by ESA. The main aim of the project is the design of a thermal control device able to deploy through passive actuation. A combined device has been designed, made up of a Pulsating Heat Pipe (PHP) foldable heat exchanger and Shape Memory Alloy (SMA) wire. The deployment of the SMA wire is conceived to be controlled by thermal contact with the heat source and by conduction along the wire. Since the heat sources are lumped and the wire is subject to convection, a temperature gradient develops along the wire. A monodimensional mode able to predict the behavior of an SMA wire subjected to a spatial temperature gradient, is presented in this paper. The results show that the system can carry out folding and unfolding cycles with rotation angles greater than 80° only if the wire is subjected to uniform temperature distribution; in the case of temperature gradient, the achievable rotation angle is about 20°. The analysis states the feasibility of the actuation system, highlighting the critical technological aspects, to lay the groundwork for the future development of the whole system

Effect of the Ambient Temperature on the Start-Up of a Multi-Evaporator Loop Thermosyphon

Two-phase heat transfer devices are becoming fairly ubiquitous; the capability to transport heat at high rates over appreciable distances, without any external pumping device, the low cost, durability and relatively simpler modeling/design process, make this technology very attractive for many thermal management applications. Indeed, such devices have been investigated in plenty of fields such as: nuclear plants, energy systems, solar heat recovery, air conditioning, electronic cooling in avionics and in railway traction. As a consequence, they can operate under different environmental conditions that can affect their behavior. Nevertheless, it is difficult to find in literature something related to the effect of the ambient temperature on the thermal performance of such devices. The actual temperature, varying the thermo-fluid properties of the fluid inside the device, the condensation and the evaporation phenomena, could be an important parameter that can affect the performance. In this work a Multi-Evaporator loop thermosyphon is tested at different ambient temperatures, ranging from -20 °C up to 30 °C. The start-up behavior, as well as the thermal performance, are analyzed by means of temperature and pressure measurements and fluid flow visualization

Numerical Simulation of a Capillary Pulsating Heat Pipe in Various Gravity Conditions

In the last two decades a new concept of capillary heat pipe without wick structures, commonly known as Pulsating Heat Pipe (PHP), entered the domain of the two-phase passive heat transfer devices. The thermal-hydraulic behavior of this mini-channel with alternate heating and cooling zones, evacuated and partially filled with a working fluid, mainly depends on the interplay between phase change phenomena, capillary and gravity, if present, which may assist or damp the fluid motion. Numerous are the attempts to simulate PHPs complex behavior, but only a few of them are capable of complete thermal-hydraulic simulations; in addition, none is able to predict the effects of various gravity levels. Nevertheless, validated numerical simulations can constitute useful tools to complete and support experimental studies, and to help the design of new and better performing PHPs. Thus, a novel lumped parameters numerical code for the transient thermo-hydraulic simulation of PHPs has been developed and validated. It consists of a two-phase separated flow model where capillary slug flow is assumed a priori. A complete set of balance differential equations accounts for homogeneous and heterogeneous phase-changes, as well as thermal and fluid-dynamic phenomena. This novel model shows a very good quantitative and qualitative prediction capability not only when computing the correct measured equivalent thermal resistance, but even when reproducing the experimental trend of temperature when transient conditions are applied. This paper presents the comparison between numerical and experimental data, for a copper PHP (I.D./O.D. 1.1mm/2.0mm) filled with FC-72 tested experimentally in micro-gravity (58th Parabolic Flight Campaign), and hyper-gravity conditions (ESA SYT!2013 Programme