818 research outputs found
Night-time shift work and related stress responses: A study on security guards
Work-related stress can induce a break in homeostasis by placing demands on the body that are met by the activation of two different systems, the hypothalamic\u2013pituitary\u2013adrenal axis and the sympathetic nervous system. Night-shift work alters the body\u2019s exposure to the natural light\u2013 dark schedule and disrupts circadian (daily) rhythms. The greatest effect of night-shift work is the disruption of circadian rhythms. The impact that these disruptions may have on the pathogenesis of many diseases, including cancer, is unknown. This study aims to discover the relationship among three different job activities of security guards and their stress-related responses by evaluating salivary cortisol levels and blood pressure. Methods: Ninety security guards, including night-time workers and night-time and daily-shift workers, were recruited for this study. Each security guard provided two saliva samples before and after three scheduled time points: (i) at 22:00, (ii) at 06:30, and (iii) at 14:00. Results: The results of the study showed a significant alteration in cortisol levels. Night-time shift cortisol levels significantly increased before and after the work shifts. A physiological prevalence of the vagal tone on the cardiocirculatory activity was found during night-shift work. Conclusions: This study indicates that cortisol levels and blood pressure are sensitive markers of biological responses to severe work stress. Shift-change consequences may occur at the end of the night shift when there is a significant increase in the cortisol level and a significant variation in cardiovascular parameters
The quest for Magrathea planets I: formation of second generation exoplanets around double white dwarfs
The evolution of binaries that become double white dwarf (DWD) can cause the
ejection of high amounts of dust and gas. Such material can give rise to
circumbinary discs and become the cradle of new planets, yet no studies so far
have focused on the formation of circumbinary planets around DWDs. These
binaries will be the main sources of gravitational waves (GWs) detectable by
the ESA Laser Interferometer Space Antenna (LISA) mission, opening the
possibility to detect circumbinary planets around short-period DWDs everywhere
in the Milky Way. We investigate the formation of Magrathea planets by
simulating multiple planet formation tracks to explore how seeds growing first
by pebble accretion, and then by gas accretion, are affected by the disc
environments surrounding DWDs. We present both planetary formation tracks
taking place in steady-state discs, and formation tracks taking place in discs
evolving with time. The time-dependent tracks account for both the disc
accretion rate onto the central binary and the disc photoevaporation rate
caused by stellar irradiation. Our results show that planetary formation in
circumbinary discs around DWDs can be possible. In particular, the extreme
planetary formation environment implies three main significant results: (i) the
accretion rate and the metallicity of the disc should be high in order to form
sub-stellar objects with masses up to 31 M, this is achieved only if planet
formation starts soon after the onset of the disc and if first generation seeds
are present in the disc; (ii) seeds formed within 0.1 Myr, or within 1 Myr,
from the onset of the disc can only produce sub-Neptune and Neptunian planets,
unless the disc accommodates first generation seeds with mass 10 M;
(iii) most of the planets are finally located within 1 au from the disc centre,
while they are still undergoing the gas accretion phase.Comment: Accepted for publication in A&A on 05/04/2023, abstract shortened, 28
pages, 11 figures, 14 table
A NEW BIOREFINERY MODEL FOR LIVESTOCK FARMING: MICROALGAE CULTIVATION FOR ANIMAL SLURRIES VALORIZATION
Development of livestock farming sector poses serious concerns on its environmental impact due to the production of huge volume of slurries characterized by high concentrations of organic and mineral pollutants, mainly in the form of ammonia, phosphates and carbon compounds.
The aim of this work was to evaluate the possibility to use microalgae as a biological tool for the depuration of such wastewaters, assimilating the nutrients and producing an added value biomass to be used in different sectors such as the food and feed, nutraceutical and bioenergy.
Chapter 1 deals with the study of a digestate treatment plant characterized by a series of physical-chemical treatments which depurate the liquid fraction of the digestate through membrane technology (ultrafiltration and reverse osmosis) allowing to discharge 50% of the slurry as clean water and to produce ammonium sulfate and nutrients-rich solids/concentrates usable as fertilizers. The ultrafiltration step produces also a clear permeate still rich in soluble nutrients that could be further used as a growth medium for microalgae production. Chapter 2 intended to demonstrate the possibility to integrate microalgae production with this system, helping to reduce the cost of slurry treatment and improving the energy balance of the process. The tolerance of the microalga Scenedesmus sp. to the permeate was evaluated, results demonstrating that percentage upper than 10% inhibited the growth of this microalga, but below this value productivity up to 124 mg L-1 d-1 could be obtained. The composition of the culture medium also influenced the biomass composition, with protein, carbohydrate and lipid content being a direct function of ammonia concentrations. It was then demonstrated that integrating microalgae production with anaerobic digestion it is possible to produce 166-190 t y-1 of microalgal valuable biomass.
Chapter 3 focused on the possibility to exploit a wild microalga strain (Chlorella sp.), isolated in the farm, to improve the depuration of the digestate and the two digestate liquid fraction after centrifugation and ultrafiltration. The results demonstrated that digestate could not support a good growth, as the other two liquid stream, because of low light availability in the culture. Ultrafiltrate, on the other hand, resulted in the best biomass productivity (0.21 g L-1d-1) comparable to that obtained in a synthetic medium. All the streams were depurated with ammonia, phosphorus and COD reduction up to 98%, 99% and 70% respectively
Besides these encouraging data it has been found that only 30% of the nitrogen were successfully incorporated in the microalgal biomass due to stripping processes, posing serious environmental concerns on the process
In Chapter 4 astaxanthin-producer Haematococcus pluvialis was cultivated in a treated swine slurry with low-cost cascade filters. Although this microalga is slow-growing and very susceptible to contamination, it showed a sustained growth (up to 60 mg L-1 d-1 of biomass) in the waste stream reducing all the pollutants present in the wastewater. Moreover it accumulated a good amount of astaxanthin, improving the overall feasibility and sustainability of the process
The Conserved nhaAR Operon Is Drastically Divergent between B2 and Non-B2 Escherichia coli and Is Involved in Extra-Intestinal Virulence
The Escherichia coli species is divided in phylogenetic groups that differ in their virulence and commensal distribution. Strains belonging to the B2 group are involved in extra-intestinal pathologies but also appear to be more prevalent as commensals among human occidental populations. To investigate the genetic specificities of B2 sub-group, we used 128 sequenced genomes and identified genes of the core genome that showed marked difference between B2 and non-B2 genomes. We focused on the gene and its surrounding region with the strongest divergence between B2 and non-B2, the antiporter gene nhaA. This gene is part of the nhaAR operon, which is in the core genome but flanked by mobile regions, and is involved in growth at high pH and high sodium concentrations. Consistently, we found that a panel of non-B2 strains grew faster than B2 at high pH and high sodium concentrations. However, we could not identify differences in expression of the nhaAR operon using fluorescence reporter plasmids. Furthermore, the operon deletion had no differential impact between B2 and non-B2 strains, and did not result in a fitness modification in a murine model of gut colonization. Nevertheless, sequence analysis and experiments in a murine model of septicemia revealed that recombination in nhaA among B2 strains was observed in strains with low virulence. Finally, nhaA and nhaAR operon deletions drastically decreased virulence in one B2 strain. This effect of nhaAR deletion appeared to be stronger than deletion of all pathogenicity islands. Thus, a population genetic approach allowed us to identify an operon in the core genome without strong effect in commensalism but with an important role in extra-intestinal virulence, a landmark of the B2 strains
Attitudes of healthcare personnel towards vaccinations before and during the covid-19 pandemic
Vaccines constitute highly effective tools for controlling and eliminating vaccine-preventable diseases (VPDs) and are assessed to avert between two to three million deaths per year globally. Healthcare personnel (HCP) constitute a priority group for several vaccinations. However, studies indicate significant rates of vaccine hesitancy among them and, therefore, of acceptance of vaccination recommendations. This cross-sectional study was conducted in a university hospital in Southern Italy to assess the knowledge and attitudes of HCP about VPDs before and during the COVID-19 pandemic, estimate their intention to get vaccinated against COVID-19, and search for determinants that may influence their choice. A self-administered questionnaire was used. HCP improved their knowledge about VPDs and were more favorable to vaccinations in September\u2013December 2020 compared to January\u2013December 2019. Overall, 75% of respondents would get a COVID-19 vaccine. Our findings indicate a potential role of the ongoing COVID-19 pandemic on Italian HCP\u2019s knowledge and attitudes towards vaccines
Editorial: Occupational risks of healthcare personnel
Healthcare personnel (HCP), and especially those working in front-line roles, are at increased risk for occupational exposure to a variety of infections, including vaccine-preventable diseases. At the same time, HCP are exposed not only to environmental risks (e.g., biological, physical, and chemical risks) but also to psychological stress, which was exceptionally intensified during the coronavirus disease 2019 (COVID-19) pandemic. As such, ensuring safety within healthcare facilities and creating health-promoting workplaces is becoming increasingly relevant in a globalizing workplace..
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