Employment level and business cycles : diferences between SME's and large firms' performance

Mestrado em EconomiaO nível de emprego e as suas flutuações são desde sempre um dos temas que maior debate suscita na literatura económica. Este estudo foca as diferenças na sensibilidade do nível de emprego ao ciclo económico existentes entre pequenas e médias empresas (PME’s) e grandes empresas na economia portuguesa. Qual o grupo de empresas que apresenta reduções mais significativas do número de trabalhadores em períodos recessivos? E em períodos de crescimento? Serão as PME’s com negócios mais frágeis ou as grandes empresas com mais trabalhadores? O debate sobre as respostas teóricas é intenso e encontra-se distante de um consenso. O estudo analisa quatro importantes sectores económicos - Construção, Comércio a Retalho, Serviços e Indústria entre 2000 e 2012. A base de dados é utilizada pela primeira vez na abordagem ao mercado de trabalho e é desenvolvida pelo Instituto Nacional de Estatística. No que respeita à economia portuguesa, para os setores estudados, as conclusões são claras, as grandes empresas apresentam maior sensibilidade ao ciclo económico, independentemente do sector de atividade, registando variações do nível de emprego mais significativas que as PME’s. Esta conclusão coloca em causa algumas ideias feitas sobre o contributo das PME’s para as variações de emprego abrindo a discussão sobre os factores determinantes destas diferenças na variação do nível de emprego entre PME’s e grandes empresas.Employment level and its fluctuations are historically one of the most discussed topics in the economic literature. This study focuses on the differences in employment’s sensitivity to the business cycle existent between small and medium enterprises (SMEs) and large companies in the Portuguese economy. Which group of firms presents a more significant reduction in employment level during a recession? And during expansions? Are those SMEs with more fragile business or large firms with more employees? The theoretical discussion is still an open debate, being far from a consensus. The study analyses four major economic sectors - Construction, Retail Trade, Services and Industry between 2000 and 2012. The database is first used for this approach to the labor market and is developed by Statistics Portugal. Regarding the Portuguese economy for the sectors studied, the conclusions are clear, large firms are more sensitive to the economic cycle, regardless of the economic sector, recording more significant employment variations than SMEs. These conclusions call into question some well known ideas about SME’s contribution to the employment variations over the business cycle, opening the discussion on the determinants of these differences between SMEs and large companies’ performance

Breaking the witches' spell: towards steering the soil microbiome for volatile-mediated control of the root parasitic weed Striga

Striga hermonthica, commonly known as witchweed, infests major cereal crops in Sub-Saharan Africa causing severe yield losses and threatening the livelihood of millions of resource poor farmers. Despite the use of herbicides, Striga-resistant crop varieties and agronomic practices to mitigate the impact of Striga, these are not effective on their own and require high monetary investments by smallholder farmers. My PhD research focuses on the potential of soil microbes to disrupt the early stages of the parasite’s life cycle through the production of volatile organic compounds. More specifically, we developed a computer vision tool that enabled the large-scale screening of a large bacterial collection for its functional potential to suppress Striga seed germination by naturally produced volatile compounds. This was complemented with the identification of several Striga-suppressive volatile compounds and studies into their genomic regulation. We developed a new approach of ‘precursor-directed activation’ of Striga-suppressive soil microbes by amending field soils with amino acid precursors to suppressive volatile compounds. This strategy will enable better deployment of volatile-mediated Striga suppression under field settings, by steering its production in situ and by aiding in the development of future control methods with higher efficacies and lower application costsBill & Melinda Gates FoundationMicrobial Biotechnolog

Plant-microbe eco-evolutionary dynamics in a changing world

Both plants and their associated microbiomes can respond strongly to anthropogenic environmental changes. These responses can be both ecological (e.g. a global change affecting plant demography or microbial community composition) and evolutionary (e.g. a global change altering natural selection on plant or microbial populations). As a result, global changes can catalyse eco-evolutionary feedbacks. Here, we take a plant-focused perspective to discuss how microbes mediate plant ecological responses to global change and how these ecological effects can influence plant evolutionary response to global change. We argue that the strong and functionally important relationships between plants and their associated microbes are particularly likely to result in eco-evolutionary feedbacks when perturbed by global changes and discuss how improved understanding of plant-microbe eco-evolutionary dynamics could inform conservation or even agriculture.</p

The Composition of Hyperacute Serum and Platelet-Rich Plasma Is Markedly Different despite the Similar Production Method

Autologous blood derived products, such as platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) are widely applied in regenerative therapies, in contrast to the drawbacks in their application, mainly deriving from the preparation methods used. Eliminating the disadvantages of both PRP and PRF, hyperacute serum (HAS) opens a new path in autologous serum therapy showing similar or even improved regenerative potential at the same time. Despite the frequent experimental and clinical use of PRP and HAS, their protein composition has not been examined thoroughly yet. Thus, we investigated and compared the composition of HAS, serum, PRP and plasma products using citrate and EDTA by simple laboratory tests, and we compared the composition of HAS, serum, EDTA PRP and plasma by Proteome Profiler and ELISA assays. According to our results the natural ionic balance was upset in both EDTA and citrate PRP as well as in plasma. EDTA PRP contained significantly higher level of growth factors and cytokines, especially platelet derived angiogenic and inflammatory proteins, that can be explained by the significantly higher number of platelets in EDTA PRP. The composition analysis of blood derivatives revealed that although the preparation method of PRP and HAS were similar, the ionic and protein composition of HAS could be advantageous for cell function

DiSCount: computer vision for automated quantification of Striga seed germination

Microbial Biotechnolog

High-resolution imaging of human atherosclerotic carotid plaques with micro18F-FDG PET scanning exploring plaque vulnerability

FDG-PET can be used to identify vulnerable plaques in atherosclerotic disease. Clinical FDG-PET camera systems are restricted in terms of resolution for the visualization of detailed inflammation patterns in smaller vascular structures. The aim of the study is to evaluate the possible added value of a high-resolution microPET system in excised carotid plaques using FDG. In this study, 17 patients with planned carotid endarterectomy were included. Excised plaques were incubated in FDG and subsequently imaged with microPET. Macrophage presence in plaques was evaluated semi-quantitatively by immunohistochemistry. Plaque calcification was assessed additionally with CT and correlated to FDG uptake. Finally, FDG uptake and macrophage infiltration were compared with patient symptomatology. Heterogeneous distributions and variable intensities of FDG uptake were found within the plaques. A positive correlation between the distribution of macrophages and the FDG uptake (r = 0.68, P <.01) was found. A negative correlation was found between areas of calcifications and FDG uptake (r = -0.84, P <.001). Ratio FDG(max) values as well as degree of CD68 accumulation were significantly higher in CVA patients compared with TIA or amaurosis fugax patients (P <.05) and CVA patients compared with asymptomatic patients (P <.05). This ex vivo study demonstrates that excised carotid plaques can be visualized in detail using FDG microPET. Enhancement of clinical PET/CT resolution for similar imaging results in patients is needed

Carotid Plaque Imaging with SPECT/CT and PET/CT

A major contributor to the occurrence of ischemic stroke is the existence of carotid atherosclerosis. A vulnerable carotid atherosclerotic plaque may rupture or erode, thus causing a thrombotic event. Currently, clinical decision-making with regard to carotid endarterectomy or stenting is still primarily based on the extent of luminal stenosis, estimated with CT angiography and/or (duplex) ultrasonography. However, there is growing evidence that the anatomic impact of stenosis alone has limited value in predicting the exact consequences of plaque vulnerability. Various molecular processes have, independently of degree of stenosis, shown to be importantly associated with the plaque's capability to cause thrombotic events. These molecular processes can be visualized with nuclear medicine techniques allowing the identification of vulnerable patients by non-invasive in vivo SPECT(/CT) and PET(/CT) imaging. This chapter provides an overview of SPECT(/CT) and PET(/CT) imaging with specific radiotracers that have been evaluated for the detection of plaques together with a future perspective in this field of imaging.</p

Breaking the witches' spell: towards steering the soil microbiome for volatile-mediated control of the root parasitic weed Striga

Striga hermonthica, commonly known as witchweed, infests major cereal crops in Sub-Saharan Africa causing severe yield losses and threatening the livelihood of millions of resource poor farmers. Despite the use of herbicides, Striga-resistant crop varieties and agronomic practices to mitigate the impact of Striga, these are not effective on their own and require high monetary investments by smallholder farmers. My PhD research focuses on the potential of soil microbes to disrupt the early stages of the parasite’s life cycle through the production of volatile organic compounds. More specifically, we developed a computer vision tool that enabled the large-scale screening of a large bacterial collection for its functional potential to suppress Striga seed germination by naturally produced volatile compounds. This was complemented with the identification of several Striga-suppressive volatile compounds and studies into their genomic regulation. We developed a new approach of ‘precursor-directed activation’ of Striga-suppressive soil microbes by amending field soils with amino acid precursors to suppressive volatile compounds. This strategy will enable better deployment of volatile-mediated Striga suppression under field settings, by steering its production in situ and by aiding in the development of future control methods with higher efficacies and lower application cost

Evaluation of 18F-fluorodeoxyglucose Micro Positron Emission Tomography Imaging in Atherosclerotic Plaques after Carotid Endarterectomy: Focus on Resolution Improvement

Introduction: Currently, imaging techniques are available to assess atherosclerotic vascular disease in the carotid artery. Hence, the selection of patients for proper medical treatment, including so-called ‘best medical treatment’; endovascular carotid artery stenting (CAS) and surgical carotid endarterectomy (CEA) is possible. However, there is a need to refine risk estimates. The majority of patients with clinical events cannot be selected using present imaging techniques. Clinical FDG PET camera’s show restrictions with respect to resolution in relation to plaque uptake. Therefore, we used removed carotid arteries of patients to evaluate the feasibility of FDG uPET for the ex-vivo assessment of plaque vulnerability. Methodology: In this study, 17 patients with planned CEA were included. The removed carotid plaque was incubated using ca.100 MBq FDG (60 min, r.t.) and subsequently imaged with uPET. CT was used to assess calcifications in the plaque. The plaque’s macrophages were evaluated semi-quantitatively using immunohistochemistry. Macrophage activity was correlated to FDG uptake in the same area. Furthermore, calcifications in the plaque were correlated to FDG-uptake. Results: We showed a heterogenous distribution and variable intensity of FDG uptake within the plaque. A positive correlation between the amount of macrophages and FDG-uptake (r= 0.68, p< 0.01) was found. Moreover, FDG uptake showed a trend towards positive correlation of FDG uptake and symptoms in patients. Furthermore, a negative correlation was found between the amount of calcifications and FDG uptake (r= -0.84, p < 0.01) Conclusion: Ex vivo FDG uptake using uPET/CT in removed carotid plaques showed a positive correlation with the amount of macrophages, as well as a trend towards positive correlation between patient symptomatology and FDG uptake. Clinical PET tends to fail to show these results in some patients, probably by lack of resolution power. More research is needed to prove the efficacy of uPET/CT for this purpose.