On the analysis of masonry structures without box behavior

Assessment of the seismic performance of structures is still challenge. Historic masonry structures exhibit peculiar properties (low tensile strength and lack of box behavior) that make the task of the analyst even more difficult. It seems that traditional design and assessment methods, similar to the ones currently used for reinforced concrete structures, are not applicable. This paper provides a review of the seismic analysis of masonry structures without box behavior. Different methods of structural analysis are discussed and a comparison is made between pushover methods and non-linear dynamic analysis with time integration. Three cases studies (S. Torcato church, Qutb Minar and “Gaioleiros” buildings) were used and the results show that traditional, adaptive or modal pushover analyses are not totally in agreement with non-linear dynamic analysis or experimental observations, namely cycle and rigid block behavior (rocking) and the out-of-plane behavior.The present work is partly funded by FCT (Portuguese Foundation for Science and Technology), through project POCI/ECM/61671/2004, "Seismic vulnerability reduction of old masonry buildings" and project PTDC-ECM-68188-2006, "Innovative solutions for non-load bearing masonry infills"

COVID-19. Pandemic surgery guidance

Abstract – Based on high quality surgery and scientific data, scientists and surgeons are committed to protecting patients as well as healthcare staff and hereby provide this Guidance to address the special issues circumstances related to the exponential spread of the Coronavirus disease 2019 (COVID-19) during this pandemic. As a basis, the authors used the British Intercollegiate General Surgery Guidance as well as recommendations from the USA, Asia, and Italy. The aim is to take responsibility and to provide guidance for surgery during the COVID-19 crisis in a simplified way addressing the practice of surgery, healthcare staff and patient safety and care. It is the responsibility of scientists and the surgical team to specify what is needed for the protection of patients and the affiliated healthcare team. During crises, such as the COVID-19 pandemic, the responsibility and duty to provide the necessary resources such as filters, Personal Protective Equipment (PPE) consisting of gloves, fluid resistant (Type IIR) surgical face masks (FRSM), filtering face pieces, class 3 (FFP3 masks), face shields and gowns (plastic ponchos), is typically left up to the hospital administration and government. Various scientists and clinicians from disparate specialties provided a Pandemic Surgery Guidance for surgical procedures by distinct surgical disciplines such as numerous cancer surgery disciplines, cardiothoracic surgery, ENT, eye, dermatology, emergency, endocrine surgery, general surgery, gynecology, neurosurgery, orthopedics, pediatric surgery, reconstructive and plastic surgery, surgical critical care, transplantation surgery, trauma surgery and urology, performing different surgeries, as well as laparoscopy, thoracoscopy and endoscopy. Any suggestions and corrections from colleagues will be very welcome as we are all involved and locked in a rapidly evolving process on increasing COVID-19 knowledg

Nitrogen Exchanges: Testing the Hypothesis of a Country without Agricultural Production

Today, finding data on agricultural nitrogen balances is quite easy. Calculations of such balances are carried out by most of the European countries as an indicator of environmental pollution attributable to the agricultural sector. In France, average values of agricultural nitrogen balances show an excess of 1.5 to 2 million tons of nitrogen. This excess is enormous. What would the balance of a country be if agricultural activity were stopped? In the following article, a country (France is used as an example) without agriculture is studied in order to assess its nitrogen balance. Using a previously published model describing nitrogen input and output of a given country, nitrogen flows are identified. Inputs include deposition, fixation, and products not intended for agricultural use. Outputs are reduced to zero if agriculture disappears (in France, agriculture is the only sector exporting products containing nitrogen). All flows are calculated considering the hypothesis of disappearance of agriculture. Nitrogen requirements to feed people and pets in France are estimated based on medical and veterinary data (recommended daily amounts for proteins and/or usual average consumption). Indeed, most of the food that nourishes the French population is produced nationally. If agriculture stops, it will be necessary to import food from foreign countries. Results show an unexpectedly high excess (for a country without agriculture having a structure similar to France: number of human beings and pets) of 1.5 million tons of nitrogen. An attempt to calculate an agricultural balance with the same data gives a result close to 3 million tons. Differences in French agricultural balances found in the literature can mainly be explained by values taken into account for deposition and fixation (values used here are at least 300,000 tons higher than values used by the Organisation for Economic Co-operation and Development). In conclusion, nitrogen excess in agriculture is partly due to social demand; agriculture does not only produce food but also includes many other functions (landscape management, employment, and preservation of culture, for example). As a consequence, efforts that do not involve suppressing agriculture should be made to figure out alternative ways of production

Dependency of hydration and growth conditions on the mechanical properties of oral biofilms

Within the oral cavity, dental biofilms experience dynamic environments, in part due to changes in dietary content, frequency of intake and health conditions. This can impact bacterial diversity and morpho-mechanical properties. While phenotypic properties of oral biofilms are closely related to their composition, these can readily change according to dynamic variations in the growth environment and nutrient availability. Understanding the interlink between phenotypic properties, variable growth conditions, and community characterization is an essential requirement to develop structure–property relationships in oral-biofilms. In this study, the impact of two distinct growth media types with increasing richness on the properties of oral biofilms was assessed through a new combination of in-vitro time-lapse biophysical methods with microbiological assays. Oral biofilms grown in the enriched media composition presented a decrease in their pH, an increase in soluble EPS production, and a severe reduction in bacterial diversity. Additionally, enriched media conditions presented an increase in biofilm volumetric changes (upon hydration) as well as a reduction in elastic modulus upon indentation. With hydration time considered a major factor contributing to changes in biofilm mechanical properties, we have shown that it is less associated than media richness. Future investigations can now use this time-lapse approach, with a clearer focus on the extracellular matrix of oral biofilms dictating their morpho-mechanical properties

Assessment of circadian rhythms in humans: comparison of real-time fibroblast reporter imaging with plasma melatonin.

We compared the period of the rhythm of plasma melatonin, driven by the hypothalamic circadian pacemaker, to in vitro periodicity in cultured peripheral fibroblasts to assess the effects on these rhythms of a polymorphism of PER3 (rs57875989), which is associated with sleep timing. In vitro circadian period was determined using luminometry of cultured fibroblasts, in which the expression of firefly luciferase was driven by the promoter of the circadian gene Arntl (Bmal1). The period of the melatonin rhythm was assessed in a 9-d forced desynchrony protocol, minimizing confounding effects of sleep-wake and light-dark cycles on circadian rhythmicity. In vitro periods (32 participants, 24.61±0.33 h, mean±sd) were longer than in vivo periods (31 participants, 24.16±0.17 h; P0.4). Analyses of replicate in vitro assessments demonstrated that circadian period was reproducible within individuals (intraclass correlation=0.62), but in vivo and in vitro period assessments did not correlate (P>0.9). In accordance with circadian entrainment theory, in vivo period correlated with the timing of melatonin (P<0.05) at baseline and with diurnal preference (P<0.05). Individual circadian rhythms can be reliably assessed in fibroblasts but may not correlate with physiological rhythms driven by the central circadian pacemaker.-Hasan, S., Santhi, N., Lazar, A.S., Slak, A., Lo, J., von Schantz, M., Archer, S. N., Johnston, J. D., Dijk, D.-J. Assessment of circadian rhythms in humans: comparison of real-time fibroblast reporter imaging with plasma melatonin