The Ricardo puzzle

This paper tackles the puzzle of Ricardo’s stubborn commitment to a labor theory of value that he himself saw as no more than an approximation to reality and which was heavily opposed by Malthus, his most respected contemporary. We show it is wrong to think that the theory had no analytical use. Quite to the contrary, it was the only defence Ricardo could find against Malthus’ destructive criticism, which introduced an unacceptable degree of indetermination in his theory of profits. By adopting the labor theory of value, Ricardo drastically simplified the method of proof of his main proposition, which otherwise seemed to present unsurmountable analytical difficulties. The irony is that the proposition was correct, quite independently of the labor theory of value, but Ricardo was just unable to prove it.

Lucro, Juros e moeda: um ensaio em dinâmica Keynesiana

Uma característica do modelo keynesiano convencional de livro-texto e a não inclusão do lucro agregado entre suas categorias de análise

Efeitos permanentes da política monetária e fiscal sob inflação

A principal intenção deste artigo é discutir os efeitos relativos das políticas fiscais e monetárias num contexto inflacionário. O problema é estudado através do modelo IS-LM, no qual o autor insere as restrições orçamentáriasdo governo e uma equação de preços. O autor assume que a economia não está em crescimento. A seção 2 discute as propriedades de um equilíbrio dinâmico em condições inflacionárias. A seção 3 discute a ação destas políticas sob a hipótese de uma Cuiva de Phillips não vertical a longo prazo e a seção 4 o faz sob a hipótese de uma taxa natural

Determinantes externos e internos da atividade econômica no Brasil

This paper aims to improve our understanding on the true determinants of aggregate output in our economy by means of a detailed investigation of the recessive episodes of 1981 and 1983. It concludes that public expenditures seem to be an important determinant of the level of activity but that is no clear evidence that the behaviour of monetary aggregates has any systematic influence on the behaviour of GDP. Selective restrictions on consumer credit and the real wage fall seem to be the main cause of the 1981 recession.Este trabalho procura melhorar o nosso entendimento sobre os verdadeiros determinantes do ritmo da produção emnossa economia através de um exame detaIhado dos episódios recessivos de 1981 e 1983. Conclui-se que os gastos públicos parecem ser um determinante importante do móvel de atividade mas não ha evidência clara que o comportamento dos agregados monetários tenha influência sistemática sobre a evolução do PIB. As restrições seletivas ao crédito ao consumidor e a queda real dos salários mais altos parecem ser a causa principal da recessão de 81

Diversity of plant growth-promoting bacteria associated with sugarcane

The sugarcane (Saccharum spp) presents economic importance, mainly for tropical regions, being an important Brazilian commodity. However, this crop is strongly dependent on fertilizers, mainly nitrogen (N). This study assessed the plant growth-promoting bacteria (PGPB) associated with sugarcane that could be used as a potential inoculant to the crop. We evaluated the genetic diversity of PGPB in the plant tissue of sugarcane varieties (RB 867515, RB 1011, and RB 92579). The primer BOX-A1R was used to differentiate the similar isolated and further sequencing 16S rRNA ribosomal gene. The 16S rRNA gene showed the presence of seven different genera distributed into four groups, the genus Bacillus, followed by Paenibacillus (20%), Burkholderia (14%), Herbaspirillum (6%), Pseudomonas (6%), Methylobacterium (6%), and Brevibacillus (3%). The molecular characterization of endophytic isolates from sugarcane revealed a diversity of bacteria colonizing this plant, with a possible biotechnological potential to be used as inoculant and biofertilizers

Maternal sensitivity and mother-infant attachment are associated with antibiotic uptake in infancy

Attachment security has been associated with health status and symptom reporting. In this longitudinal study, we investigated the association between antibiotics uptake by infants at 9-months and mother-infant attachment at 12-months. Logistic regression analyses indicated that lower maternal sensitivity was associated with increased odds of antibiotic uptake. Furthermore, 89.7% of insecure-ambivalent infants consumed antibiotics, which contrasted with 32.5% of avoidant infants and 21.5% of secure infants. This study suggests that maternal behavior and mother-infant attachment impact on antibiotic consumption, which is worrying because antibiotics may lead to several health problems later in life and antibiotic-resistance.info:eu-repo/semantics/publishedVersio

Development and assessment of an over-expanded engine to be used as an efficiency-oriented range extender for electric vehicles

A range extender (RE) is a device used in electric vehicles (EVs) to generate electricity on-board, enabling them to significantly reduce the number of required batteries and/or extend the vehicle driving range to allow occasional long trips. In the present work, an efficiency-oriented RE based on a small motorcycle engine modified to the efficient over-expanded cycle, was analyzed, tested and simulated in a driving cycle. The RE was developed to have two points of operation, ECO: 3000 rpm, very high efficiency with only 15 kW; and BOOST: 7000 rpm with 35 kW. While the ECO strategy was a straightforward development for the over-expansion concept (less trapped air and a much higher compression ratio) the BOOST strategy was more complicated to implement and involved the need for throttle operation. Initially the concepts were evaluated in an in-house model and AVL Boost® (AVL List Gmbh, Graz, Austria), and proved feasible. Then, a BMW K75 engine was altered and tested on a brake dynamometer. The running engine proved the initial concept, by improving the efficiency for the ECO condition in almost 40% in relation to the stock engine and getting well over the required BOOST power, getting to 35 kW, while keeping an efficiency similar to the stock engine at the wide open throttle (WOT). In order to protect the engine during BOOST, the mixture was enriched, while at ECO the mixture was leaned to further improve efficiency. The fixed operation configuration allows the reduction, not only of complexity and cost of the RE, but also the set point optimization for the engine and generator. When integrated as a RE into a typical European light duty vehicle, it provided a breakthrough consumption reduction relatively to existing plug-in hybrid electric vehicles (PHEVs) in the market in the charge sustaining mode. The very high efficiency of the power generation seems to compensate for the loss of efficiency due to the excess electricity production, which must be stored in the battery. The results indicate that indeed it is possible to have an efficient solution, in-line with the electric mobility sustainability paradigm, which can solve most of the shortcomings of current EVs, notably those associated with batteries (range, cost and charging time) in a sustainable way.This Research was funded by MIT-Portugal EDAM, FCT, ERDF through Programa Operacional Fatores de Competitividade-COMPETE and National funds through PIDDAC, Project references MIT-Pt/EDAM-SMS/0030/2008 (MOBI-MPP-Assessment and Development of Integrated Systems for Electric Vehicles of the), UID/EMS/04077/2019 (MEtRICs -Mechanical Engineering and Resource Sustainability Centre Strategig Project) and grant numbers SFRH/BPD/89553/2012 (F.P. Brito) and SFRH/BSAB/142994/2018 (J Martins). AVL LIST GmbH provided free of charge an AVL Boost license through the University Partnership Program

Vascular smooth muscle contraction in hypertension

Hypertension is a major risk factor for many common chronic diseases, such as heart failure, myocardial infarction, stroke, vascular dementia, and chronic kidney disease. Pathophysiological mechanisms contributing to the development of hypertension include increased vascular resistance, determined in large part by reduced vascular diameter due to increased vascular contraction and arterial remodelling. These processes are regulated by complex-interacting systems such as the renin-angiotensin-aldosterone system, sympathetic nervous system, immune activation, and oxidative stress, which influence vascular smooth muscle function. Vascular smooth muscle cells are highly plastic and in pathological conditions undergo phenotypic changes from a contractile to a proliferative state. Vascular smooth muscle contraction is triggered by an increase in intracellular free calcium concentration ([Ca2+]i), promoting actin–myosin cross-bridge formation. Growing evidence indicates that contraction is also regulated by calcium-independent mechanisms involving RhoA-Rho kinase, protein Kinase C and mitogen-activated protein kinase signalling, reactive oxygen species, and reorganization of the actin cytoskeleton. Activation of immune/inflammatory pathways and non-coding RNAs are also emerging as important regulators of vascular function. Vascular smooth muscle cell [Ca2+]i not only determines the contractile state but also influences activity of many calcium-dependent transcription factors and proteins thereby impacting the cellular phenotype and function. Perturbations in vascular smooth muscle cell signalling and altered function influence vascular reactivity and tone, important determinants of vascular resistance and blood pressure. Here, we discuss mechanisms regulating vascular reactivity and contraction in physiological and pathophysiological conditions and highlight some new advances in the field, focusing specifically on hypertension