4,179 research outputs found
Influence of technological progress and renewability on the sustainability of ecosystem engineers populations
Overpopulation and environmental degradation due to inadequate resource-use
are outcomes of human's ecosystem engineering that has profoundly modified the
world's landscape. Despite the age-old concern that unchecked population and
economic growth may be unsustainable, the prospect of societal collapse remains
contentious today. Contrasting with the usual approach to modeling human-nature
interactions, which are based on the Lotka-Volterra predator-prey model with
humans as the predators and nature as the prey, here we address this issue
using a discrete-time population dynamics model of ecosystem engineers. The
growth of the population of engineers is modeled by the Beverton-Holt equation
with a density-dependent carrying capacity that is proportional to the number
of usable habitats. These habitats (e.g., farms) are the products of the work
of the individuals on the virgin habitats (e.g., native forests), hence the
denomination engineers of ecosystems to those agents. The human-made habitats
decay into degraded habitats, which eventually regenerate into virgin habitats.
For slow regeneration resources, we find that the dynamics is dominated by
cycles of prosperity and collapse, in which the population reaches vanishing
small densities. However, increase of the efficiency of the engineers to
explore the resources eliminates the dangerous cyclical patterns of feast and
famine and leads to a stable equilibrium that balances population growth and
resource availability. This finding supports the viewpoint of growth optimists
that technological progress may avoid collapse
The challenges of pain management in primary care: a pan-European survey
BACKGROUND: The OPENMinds Primary Care group is a group of European primary care physicians (PCPs) with an interest in pain management, formed to improve the understanding and management of chronic pain in primary care. OBJECTIVE: A survey was conducted to assess the challenges of chronic nonmalignant pain (CNMP) management in primary care in Europe, focusing particularly on pain assessment, opioid therapy, and educational needs. METHODS: A questionnaire was developed for online use by PCPs in 13 European countries (Belgium, Denmark, France, Germany, Ireland, Italy, the Netherlands, Norway, Poland, Portugal, Spain, Sweden, and the UK). RESULTS: A total of 1309 PCPs completed the questionnaire, approximately 100 from each country. Most PCPs (84%) perceived CNMP to be one of the most challenging conditions to treat, yet a low priority within healthcare systems. Only 48% of PCPs used pain assessment tools, and 81% considered chronic pain and its impact on quality of life to be underassessed in primary care. PCPs were less confident about prescribing strong opioids for CNMP than for use in cancer pain. Most PCPs (84%) considered their initial training on CNMP was not comprehensive, with 89% recognizing a need for more education on the topic. CONCLUSION: These findings reveal that PCPs in Europe find CNMP a challenge to treat. Areas to address with training include underuse of pain assessment tools and lack of confidence in use of opioid therapy. Guidelines on CNMP management in primary care would be welcomed. The insights gained should provide the basis for future initiatives to support primary care management of chronic pain
Cardiac Troponin T and Illness Severity in the Very-Low-Birth-Weight Infant
Introduction. Respiratory distress are very common in Very-low-birth-weight (VLBW) infants and Myocardial injury may play a role in the disease outcome. Cardiac troponin T (cTnT) is the most useful marker of injury in adult population, but has not been extensively studied in this population. Aim. To study the role of cTnT in VLBW infants and its association with clinical outcomes. Methods. All VLBW infants admitted to our NICU were included in the study. Echocardiography and blood samples for cTnT determination were collected at 24 and 48 hours of life, and values >0.1 ng/mL were considered CTnT-positive values. Results. A total of 116 neonates had their blood samples collected. The median cTnT concentration within 24 hours was 0.191 (0.1–0.79) ng/mL and within 48 hours was 0.293 (0.1–1.0) ng/mL. A logistic regression analysis showed that PDA, low GA, and use of dopamine were independently associated with positive cTnT and abnormal Dopplerfluxometry and diuretics use had protective effects and was independently associated with troponin values. Conclusion. We observed a high prevalence of positivecTnT values in VLBW infants associated with illness severity. Our findings suggest that cTnT may be a useful and early marker of myocardial injury in VLBW infants
Computer analysis of human belligerency
War is a cause of gains and losses. Economic historians have long stressed the extreme importance of considering the economic potential of society for belligerency, the role of management of chaos to bear the costs of battle and casualties, and ingenious and improvisation methodologies for emergency management. However, global and inter-temporal studies on warring are missing. The adoption of computational tools for data processing is a key modeling option with present day resources. In this paper, hierarchical clustering techniques and multidimensional scaling are used as efficient instruments for visualizing and describing military conflicts by electing different metrics to assess their characterizing features: time, time span, number of belligerents, and number of casualties. Moreover, entropy is adopted for measuring war complexity over time. Although wars have been an important topic of analysis in all ages, they have been ignored as a subject of nonlinear dynamics and complex system analysis. This paper seeks to fill these gaps in the literature by proposing a quantitative perspective based on algorithmic strategies. We verify the growing number of events and an explosion in their characteristics. The results have similarities to those exhibited by systems with increasing volatility, or evolving toward chaotic-like behavior. We can question also whether such dynamics follow the second law of thermodynamics since the adopted techniques reflect a system expanding the entropy.publishersversionpublishe
Fractional dynamics and pseudo-phase space of country economic processes
In this paper, the fractional calculus (FC) and pseudo-phase space (PPS) techniques are combined for modeling the dynamics of world economies, leading to a new approach for forecasting a country's gross domestic product. In most market economies, the decline of the post-war prosperity brought challenging rivalries to the Western world. Considerable social, political, and military unrest is today spreading in major capital cities of the world. As global troubles including mass migrations and more abound, countries' performance as told by PPS approaches can help to assess national ambitions, commercial aggression, or hegemony in the current global environment. The 1973 oil shock was the turning point for a long-run crisis. A PPS approach to the last five decades (1970-2018) demonstrates that convergence has been the rule. In a sample of 15 countries, Turkey, Russia, Mexico, Brazil, Korea, and South Africa are catching-up to the US, Canada, Japan, Australia, Germany, UK, and France, showing similarity in many respects with these most developed countries. A substitution of the US role as great power in favor of China may still be avoided in the next decades, while India remains in the tail. The embedding of the two mathematical techniques allows a deeper understanding of the fractional dynamics exhibited by the world economies. Additionally, as a byproduct we obtain a foreseeing technique for estimating the future evolution based on the memory of the time series.publishersversionpublishe
“Traje português” e Historiografia Novilatina: Damião de Góis e Jerónimo Osório como excepções ao perfil do relutante historiador humanista português
A ordem real de editar o De rebus Emanuelis gestis foi crucial contra a enraizada escusa dos humanistas lusos à historiografia, mas é destacável o papel do autor do texto-base, Damião de Góis, que se afastou da “apagada e vil tristeza” pelo
temperamento apaixonado e experiência internacional.The publication of De rebus Emmanuelis Gestis, by royal command, was a crucial move against the Portuguese humanists’ entrenched unwillingness to engage in the writing of history. However, Damião de Góis, the author of the original text, was notable for his avoidance of what Camões called ‘apagada e vil tristeza’, because of his passionate temperament and international experience.info:eu-repo/semantics/publishedVersio
International Open Innovation Strategies of Firms in European Peripheral Regions
The involvement of companies in different open innovation activities, through knowledge
outputs and inputs, has become increasingly important for the success of companies. However, the
existing literature on open innovation is scarce concerning the internationalization process of companies. The internationalization of companies is fundamental in the continuous search to increase the
performance of companies externally. The objective of the present research is to explain the strategic
processes in the internationalization of companies located in peripheral regions at the time of the
COVID-19 pandemic from the perspective of dynamic capabilities. The sample used for this research
is composed of seven Portuguese companies. The methodology of qualitative nature is exploratory
and uses a case study approach. Regarding the foremost modes of operation in international markets
and strategies, we find that (1) companies have partnerships with local distributors or appoint exclusive importers/distributors, and (2) companies prefer to place their products in the market through
their brand, “co-branded” projects with retailers, or “private label” projects. Of the seven companies
under study, six use a standardization strategy, and one opts for a configuration-coordination strategy.
Our findings clarified the literature on export and internationalization strategies in a peripheral
country, allowing a closer incept of the organizational and dynamic capabilities and an overview of
the supporting tools these companies have to compete in the global market. Our study is original because few articles study the internationalization strategies of companies at the time of the COVID-19
pandemic and in peripheral regions of Europe.info:eu-repo/semantics/publishedVersio
On the Numerical Computation of the Mittag-Leffler Function
The Mittag-Leffler function (MLF) plays an important role in many applications of fractional calculus, establishing a connection between exponential and power law behaviors that characterize integer and fractional order phenomena, respectively. Nevertheless, the numerical computation of the MLF poses problems both of accuracy and convergence. In this paper, we study the calculation of the 2-parameter MLF by using polynomial computation and integral formulas. For the particular cases having Laplace transform (LT) the method relies on the inversion of the LT using the fast Fourier transform. Experiments with two other available methods compare also the computational time and accuracy. The 3-parameter MLF and its calculation are also considered.publishe
Lipid nanocarriers for anti-HIV therapeutics: a focus on physicochemical properties and biotechnological advances
Since HIV was first identified, and in a relatively short period of time, AIDS has become one of the most devastating infectious diseases of the 21st century. Classical antiretroviral therapies were a major step forward in disease treatment options, significantly improving the survival rates of HIV-infected individuals. Even though these therapies have greatly improved HIV clinical outcomes, antiretrovirals (ARV) feature biopharmaceutic and pharmacokinetic problems such as poor aqueous solubility, short half-life, and poor penetration into HIV reservoir sites, which contribute to the suboptimal efficacy of these regimens. To overcome some of these issues, novel nanotechnology-based strategies for ARV delivery towards HIV viral reservoirs have been proposed. The current review is focused on the benefits of using lipid-based nanocarriers for tuning the physicochemical properties of ARV to overcome biological barriers upon administration. Furthermore, a correlation between these properties and the potential therapeutic outcomes has been established. Biotechnological advancements using lipid nanocarriers for RNA interference (RNAi) delivery for the treatment of HIV infections were also discussed.This research was funded by FCT/MCTES—Foundation for Science and Technology
I.P. from the Minister of Science, Technology, and Higher Education (PIDDAC) and European
Regional Development Fund (ERDF) by the COMPETE—Programa Operacional Factores de Competitividade (POFC) through the project CONCERT [POCI-01-0145-FEDER-032651 and PTDC/NANMAT/326512017] and the Strategic Funding UID/FIS/04650/2019 and “Contrato-Programa” UIDB/
04469/2020 (CF-UM-UP and CBMA). Marlene Lúcio thanks FCT and ERDF for the doctoral position
[CTTI-150/18-CF (1)] in the scope of the project CONCERT. Maria João Faria thanks FCT for PhD
grant [2020.06561.BD]
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