260 research outputs found
A systematic variation of the stellar initial mass function in early-type galaxies
Much of our knowledge of galaxies comes from analysing the radiation emitted
by their stars. It depends on the stellar initial mass function (IMF)
describing the distribution of stellar masses when the population formed.
Consequently knowledge of the IMF is critical to virtually every aspect of
galaxy evolution. More than half a century after the first IMF determination,
no consensus has emerged on whether it is universal in different galaxies.
Previous studies indicated that the IMF and the dark matter fraction in galaxy
centres cannot be both universal, but they could not break the degeneracy
between the two effects. Only recently indications were found that massive
elliptical galaxies may not have the same IMF as our Milky Way. Here we report
unambiguous evidence for a strong systematic variation of the IMF in early-type
galaxies as a function of their stellar mass-to-light ratio, producing
differences up to a factor of three in mass. This was inferred from detailed
dynamical models of the two-dimensional stellar kinematics for the large
Atlas3D representative sample of nearby early-type galaxies spanning two orders
of magnitude in stellar mass. Our finding indicates that the IMF depends
intimately on a galaxy's formation history.Comment: 4 pages, 2 figures, LaTeX. Accepted for publication as a Nature
Letter. More information about our Atlas3D project is available at
http://purl.org/atlas3
Perspectives for next generation lithium-ion battery cathode materials
Transitioning to electrified transport requires improvements in sustainability, energy density, power density, lifetime, and approved the cost of lithium-ion batteries, with significant opportunities remaining in the development of next-generation cathodes. This presents a highly complex, multiparameter optimization challenge, where developments in cathode chemical design and discovery, theoretical and experimental understanding, structural and morphological control, synthetic approaches, and cost reduction strategies can deliver performance enhancements required in the near- and longer-term. This multifaceted challenge requires an interdisciplinary approach to solve, which has seen the establishment of numerous academic and industrial consortia around the world to focus on cathode development. One such example is the Next Generation Lithium-ion Cathode Materials project, FutureCat, established by the UKâs Faraday Institution for electrochemical energy storage research in 2019, aimed at developing our understanding of existing and newly discovered cathode chemistries. Here, we present our perspective on persistent fundamental challenges, including protective coatings and additives to extend lifetime and improve interfacial ion transport, the design of existing and the discovery of new cathode materials where cation and cation-plus-anion redox-activity can be exploited to increase energy density, the application of earth-abundant elements that could ultimately reduce costs, and the delivery of new electrode topologies resistant to fracture which can extend battery lifetime
Perspectives for next generation lithium-ion battery cathode materials
Transitioning to electrified transport requires improvements in sustainability, energy density, power density, lifetime, and approved the cost of lithium-ion batteries, with significant opportunities remaining in the development of next-generation cathodes. This presents a highly complex, multiparameter optimization challenge, where developments in cathode chemical design and discovery, theoretical and experimental understanding, structural and morphological control, synthetic approaches, and cost reduction strategies can deliver performance enhancements required in the near- and longer-term. This multifaceted challenge requires an interdisciplinary approach to solve, which has seen the establishment of numerous academic and industrial consortia around the world to focus on cathode development. One such example is the Next Generation Lithium-ion Cathode Materials project, FutureCat, established by the UKâs Faraday Institution for electrochemical energy storage research in 2019, aimed at developing our understanding of existing and newly discovered cathode chemistries. Here, we present our perspective on persistent fundamental challenges, including protective coatings and additives to extend lifetime and improve interfacial ion transport, the design of existing and the discovery of new cathode materials where cation and cation-plus-anion redox-activity can be exploited to increase energy density, the application of earth-abundant elements that could ultimately reduce costs, and the delivery of new electrode topologies resistant to fracture which can extend battery lifetime.</jats:p
Defect-Assisted Photoinduced Halide Segregation in Mixed-Halide Perovskite Thin Films
Solution-processable
metal halide perovskites show immense promise
for use in photovoltaics and other optoelectronic applications. The
ability to tune their bandgap by alloying various halide anions (for
example, in CH<sub>3</sub>NH<sub>3</sub>PbÂ(I<sub>1â<i>x</i></sub>Br<sub><i>x</i></sub>)<sub>3</sub>, 0 < <i>x</i> < 1) is however hampered by the reversible photoinduced
formation of sub-bandgap emissive states. We find that ion segregation
takes place via halide defects, resulting in iodide-rich low-bandgap
regions close to the illuminated surface of the film. This segregation
may be driven by the strong gradient in carrier generation rate through
the thickness of these strongly absorbing materials. Once returned
to the dark, entropically driven intermixing of halides returns the
system to a homogeneous condition. We present approaches to suppress
this process by controlling either the internal light distribution
or the defect density within the film. These results are relevant
to stability in both single- and mixed-halide perovskites, leading
the way toward tunable and stable perovskite thin films for photovoltaic
and light-emitting applications
Corporate Philanthropic Responses to Emergent Human Needs: The Role of Organizational Attention Focus
Evidence for biological roots in the transgenerational transmission of intimate partner violence
Intimate partner violence is a ubiquitous and devastating phenomenon for which effective interventions and a clear etiological understanding are still lacking. A major risk factor for violence perpetration is childhood exposure to violence, prompting the proposal that social learning is a major contributor to the transgenerational transmission of violence. Using an animal model devoid of human cultural factors, we showed that male rats became highly aggressive against their female partners as adults after exposure to non-social stressful experiences in their youth. Their offspring also showed increased aggression toward females in the absence of postnatal fatherâoffspring interaction or any other exposure to violence. Both the females that cohabited with the stressed males and those that cohabited with their male offspring showed behavioral (including anxiety- and depression-like behaviors), physiological (decreased body weight and basal corticosterone levels) and neurobiological symptoms (increased activity in dorsal raphe serotonergic neurons in response to an unfamiliar male) resembling the alterations described in abused and depressed women. With the caution required when translating animal work to humans, our findings extend current psychosocial explanations of the transgenerational transmission of intimate partner violence by strongly suggesting an important role for biological factors
Altered 5-HT2C receptor agonist-induced responses and 5-HT2C receptor RNA editing in the amygdala of serotonin transporter knockout mice
How are compassion fatigue, burnout, and compassion satisfaction affected by quality of working life? Findings from a survey of mental health staff in Italy
BACKGROUND:
Quality of working life includes elements such as autonomy, trust, ergonomics, participation, job complexity, and work-life balance. The overarching aim of this study was to investigate if and how quality of working life affects Compassion Fatigue, Burnout, and Compassion Satisfaction among mental health practitioners.
METHODS:
Staff working in three Italian Mental Health Departments completed the Professional Quality of Life Scale, measuring Compassion Fatigue, Burnout, and Compassion Satisfaction, and the Quality of Working Life Questionnaire. The latter was used to collect socio-demographics, occupational characteristics and 13 indicators of quality of working life. Multiple regressions controlling for other variables were undertaken to predict Compassion Fatigue, Burnout, and Compassion Satisfaction.
RESULTS:
Four hundred questionnaires were completed. In bivariate analyses, experiencing more ergonomic problems, perceiving risks for the future, a higher impact of work on life, and lower levels of trust and of perceived quality of meetings were associated with poorer outcomes. Multivariate analysis showed that (a) ergonomic problems and impact of work on life predicted higher levels of both Compassion Fatigue and Burnout; (b) impact of life on work was associated with Compassion Fatigue and lower levels of trust and perceiving more risks for the future with Burnout only; (c) perceived quality of meetings, need of training, and perceiving no risks for the future predicted higher levels of Compassion Satisfaction.
CONCLUSIONS:
In order to provide adequate mental health services, service providers need to give their employees adequate ergonomic conditions, giving special attention to time pressures. Building trustful relationships with management and within the teams is also crucial. Training and meetings are other important targets for potential improvement. Additionally, insecurity about the future should be addressed as it can affect both Burnout and Compassion Satisfaction. Finally, strategies to reduce possible work-life conflicts need to be considered
Designed biosynthesis of 25-methyl and 25-ethyl ivermectin with enhanced insecticidal activity by domain swap of avermectin polyketide synthase
Stuck in time â a new Chaenothecopsis species with proliferating ascomata from Cunninghamia resin and its fossil ancestors in European amber
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