Firm Size Distribution under Horizontal and Vertical R&D

This paper studies the firm size distribution arising from an endogenous growth model of quality ladders with expanding variety. The probability distribution function of a given cohort of firms is a Poisson distribution that converges asymptotically to a normal of log size. However, due to firm entry propelled by horizontal R&D, the total distribution - i.e., when the entire population of firms is considered - is a mixture of Poisson distributions which is systematically right skewed and exhibits a fatter upper tail than the normal distribution of log size. Our theoretical results qualitatively match the empirical evidence found both for the cohort and the total distribution, and which has been presented as a challenge for theory to explain. Moreover, by obtaining a total distribution with a gradually falling variance over a long time span, the model is able to address complementary empirical evidence that points to a total distribution subtly evolving over time.Firm size distribution; Skewness; Heavy tails; Endogenous growth; Horizontal and vertical R&D

Is Mass Higher Education Working? An Update and a Reflection on the Sustainability of Higher Education Expansion in Portugal

The appeal of HE expansion has been particularly significant in the case of Portugal, whose levels of qualification of the labour force have been historically low. Over the last two decades the country has experience a massive expansion of its higher education system and the numbers of students enrolled and rates of enrolment have multiplied more than four times. This paper focus on the sustainability of this trend of higher education (HE) expansion in Portugal and attempts to update and rebalance a debate that is too often carried out exclusively from a supply-side perspective. The paper develops an empirical framework which incorporates the diversity of jobs currently carried out by university graduates and their changing skill requirements but that also provides a useful benchmark to refer to growing expectations mismatches among graduates. Using a new typology of graduate-level jobs and staff logs data collected annually by the Portuguese Government for private sector employees, the paper analyses the increasing dispersion of graduates’ relative earnings and relates this trend to the increasing diversification of their jobs. The paper also tests more directly the impact of over-education (relative to the graduate jobs’ current skill requirements) and finds that the relative penalty associated with this condition has increased during the 1995-2005 period. The paper then questions the extent to which Portugal can continue to be portrayed as a straightforward success story regarding the massification of HE and considers the implications regarding political and social support for continuing expansion in the system.human capital; higher education massification; demand for graduates; over-education; inequality

Nematoxic effect of essential oils and their fractions against the pinewood nematode, Bursaphelenchus xylophilus

The pinewood nematode (PWN) Bursaphelenchus xylophilus is a highly pathogenic plant parasite that greatly affects pine forests. In Portugal, the most affected species is Pinus pinaster Aiton. Despite great efforts, since its fist detection in 1999, the PWN has spread through the country, including Madeira Island, having been recently detected in Spain [1,2]. Containing this pest is of the utmost importance for European pine forest safeguard. Since most synthetic chemicals used to control phytoparasites are toxic to humans and animals, and can accumulate in the soil and in food plants [3], in the present work, the nematoxic potential of over 80 essential oils (EOs), isolated from the Portuguese flora, were assessed against the PWN. EOs were isolated by hydrodistillation and analysed by GC and GC-MS [3]. EOs hydrocarbon and oxygen-containing fractions were obtained as in [4]. Direct-contact assays, adapted from [3], were performed by adding EOs/methanol stock-solutions to 50-100 mixed-stage PWN suspensions. After 24h in darkness, dead and live nematodes were counted under an inverted microscope. Assays were repeated at least 10 times in two series. Mortalities ≥96% were obtained with 2μL/mL of the EOs isolated from Cymbopogon citratus, Eucalyptus citriodora, Mentha arvensis, Origanum virens, Origanum vulgare, Ruta graveolens, Satureja montana, Syzygium aromaticum, Thymbra capitata, Thymus caespititius (carvacrol and/or thymol-rich), Thymus vulgaris and Thymus zygis. These EOs were further tested at 1, 0.5 and 0.25μL/mL. Minimum lethal concentrations (LC100) <0.4μL/mL, were obtained for the 2-undecanone-rich R. graveolens EO and the carvacrol and γ-terpinene-rich S. montana and T. capitata EOs. Assays with EO fractions revealed that the monoterpene-rich nematoxic EOs control PWN through their combined hydrocarbon and oxygen-containing fractions through additive and/or synergic relations. As complex mixtures of active components, EOs may prove to be effective nematoxic age nts

The Consequences of a Reduced Superlattice Thickness on Quantum Cascade LASER Performance

Coherent infrared radiation sources are essential for the operability of a wide range of scientific, industrial, military and commercial systems. The importance of the mid-infrared spectral region cannot be understated. Numerous molecules have some vibrational band in this range, allowing for identification of species by means of absorption, emission or some other form of spectroscopy. As such, spectroscopy alone has numerous applications ranging from industrial process control to disease diagnosis utilizing breath analysis. However, despite the discovery of the LASER in the 60s, to this day the amount of coherent sources in this range is limited. It is for this reason that the quantum cascade laser has gained such momentum over the past 23 years. Quantum Cascade LASERS (QCL) are semiconductor LASERS which are based on the principle of bandgap engineering. This incredible technique is a testament to the technological maturity of the semiconductor industry. It has been demonstrated that by having precise control of individual material composition (band gap control), thicknesses on the order of monolayers, and doping levels for each individual layer in a superlattice, we have unprecedented flexibility in designing a LASER or detector in the infrared. And although the technology has matured since it\u27s discovery, there still remain fundamental limitations on device performance. In particular, active region overheating limits QCL performance in a high duty cycle mode of operation. In this dissertation, along with general discussion on the background of the QCL, we propose a solution of where by limiting the growth of the superlattice to a fraction of typical devices, we allow for reduction of the average superlattice temperature under full operational conditions. The consequences of this reduction are explored in theory, experiment and system level applications

Monetary Policy in Brazil: Remarks on the Inflation Targeting Regime, Public Debt Management and Open Market Operations

The purpose of this paper is to analyze the main features in the conduct of monetary policy in Brazil. Initially, we focus on the inflation targeting regime, reviewing the background that led to its adoption in mid-1999, the institutional framework implemented in the country, and the challenges and achievements reached so far. Then we move to the analysis of the public debt management, highlighting its objectives and results, with particular emphasis on the debt composition and average maturity. The third section discusses the open market procedures. The paper ends with a brief description of specific policy issues to be addressed by the Central Bank in the near future.

Control of the pinewood nematode Bursaphelenchus xylophilus by essential oils and extracts obtained from plants: a review.

The pinewood nematode (PWN), Bursaphelenchus xylophilus, is a serious threat to forest ecosystems at a global scale. The nematode has become a major quarantine problem due to its capability to completely destroy Pinus spp. trees, with great damage to the wood industry. Controlling the nematode inside a living tree is quite difficult, the techniques used being often ineffective and quite expensive. In the coming years, most chemicals used to control nematodes will be banned and replaced by safer and environmentally friendly products. As so, chemicals naturally produced by plants will play an important role in controlling diseases such as pine wilt. Plants, particularly aromatic ones, are commonly used due to the chemical properties of their secondary metabolites. Among these, essential oils and/or extracts are highly employed and are being tested as possible control of some organisms, like nematodes. Recent publications have evaluated essential oils derived from different plant species as natural nematicides [1; 2], antibacterial [3], anti-fungal [4] as well as insecticidal [5]. Concerning control of the PWN, a significant amount of information on plants tested, results obtained and employed techniques, is available. Our revision has extensively gathered this information, making it easier to search, read and use. It may become useful information for future studies on the subject, since it will be possible to check the plants already tested. Although numbers aren´t definitive, so far, tested plants are distributed amongst 148 families. The extracts or essential oils of plants belonging to the Asteraceae, Lamiaceae and Euphorbiaceae families show promising results on controlling the pinewood nematode

Ambiguous boundaries between exclusion and inclusion. Experiences from the Meheba Refugee Camp (Zambia)

Refugee camps are often created and portrayed as places of exclusion where “supernumerary” (Bauman 2004), “undesired populations” (Agier 2011) are concentrated. And yet, experiences from the Meheba Refugee Settlement show that the reality is rather more complex, providing evidence of the ambiguous line between inclusion and exclusion involving refugees and the neighbouring population.info:eu-repo/semantics/publishedVersio

Depicting protracted refuge. Postcards from a refugee camp

This essay confronts the viewer with protracted refuge by looking at the Meheba Refugee Camp, Zambia. Created in 1971 and still running well beyond the moment of emergency at its origin, Meheba challenges the generic and generalized visual representation of refugees and refugee camps. This photo-essay seeks to depict how displaced populations forge a life in exile in spite of all the adversities, but also of how the spaces of refuge evolve, consolidate, and become part of the territory in which they are located.info:eu-repo/semantics/publishedVersio