Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
J Chem Theory Comput ; 19(19): 6745-6760, 2023 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-37708349

RESUMO

We simulate X-ray absorption spectra at elemental K-edges using time-dependent density functional theory (TDDFT) in both its conventional linear-response implementation and its explicitly time-dependent or "real-time" formulation. Real-time TDDFT simulations enable broadband spectra calculations without the need to invoke frozen occupied orbitals ("core/valence separation"), but we find that these spectra are often contaminated by transitions to the continuum that originate from lower-energy core and semicore orbitals. This problem becomes acute in triple-ζ basis sets, although it is sometimes sidestepped in double-ζ basis sets. Transitions to the continuum acquire surprisingly large dipole oscillator strengths, leading to spectra that are difficult to interpret. Meaningful spectra can be recovered by means of a filtering technique that decomposes the spectrum into contributions from individual occupied orbitals, and the same procedure can be used to separate L- and K-edge spectra arising from different elements within a given molecule. In contrast, conventional linear-response TDDFT requires core/valence separation but is free of these artifacts. It is also significantly more efficient than the real-time approach, even when hundreds of individual states are needed to reproduce near-edge absorption features and even when Padé approximants are used to reduce the real-time simulations to just 2-4 fs of time propagation. Despite the cost, the real-time approach may be useful to examine the validity of the core/valence separation approximation.

2.
Healthcare (Basel) ; 11(10)2023 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-37239689

RESUMO

The workplace is a vital setting to support positive mental health. Mental health conditions in the workforce contribute to decreased work engagement and participation. There is existing literature on return-to-work (RTW) interventions for individuals with work-related mental health conditions, however, there lacks consensus on their effectiveness. Therefore, the primary aim of this systematic review was to synthesize the literature and evaluate the effectiveness of return-to-work interventions on return-to-work rates, quality of life, and psychological wellbeing for individuals with work-related mental health conditions. Selected articles were organized and identified using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and the Population/Intervention/Comparison/Outcome (PICO) framework. Quality assessment of the included studies was completed using the Critical Appraisal Skills Programme randomized controlled trials checklist and the Joanna Briggs Institute quasi-experimental studies checklist. A random effects meta-analysis model was performed using DerSimonian-Laird weighting to calculate standard mean difference and risk ratios to assess the impact of RTW interventions on return-to-work rates, absenteeism, stress symptoms, depression symptoms, and quality of life. A total of 28 out of 26,153 articles met the inclusion criteria. Diagnoses for participants in the studies ranged from work-related stress to work-related PTSD following exposure to a psychologically traumatizing event in the workplace. No significant differences were found for the meta-analyses examining return-to-work rates, absenteeism, depression, stress, and quality of life. The most effective interventions were found to be a multi-domain intervention (67% of participants RTW full time) and a health-focused intervention (85% RTW rate). Future research may consider establishing effective interventions to develop programs or policies supporting the RTW of employees and promote mental well-being among employees experiencing work-related mental health conditions.

3.
Health Policy Plan ; 38(7): 789-798, 2023 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-37256762

RESUMO

Responsive primary health-care facilities are the foundation of resilient health systems, yet little is known about facility-level processes that contribute to the continuity of essential services during a crisis. This paper describes the aspects of primary health-care facility resilience to coronavirus disease 2019 (COVID-19) in eight countries. Rapid-cycle phone surveys were conducted with health facility managers in Bangladesh, Burkina Faso, Chad, Guatemala, Guinea, Liberia, Malawi and Nigeria between August 2020 and December 2021. Responses were mapped to a validated health facility resilience framework and coded as binary variables for whether a facility demonstrated capacity in eight areas: removing barriers to accessing services, infection control, workforce, surge capacity, financing, critical infrastructure, risk communications, and medical supplies and equipment. These self-reported capacities were summarized nationally and validated with the ministries of health. The analysis of service volume data determined the outcome: maintenance of essential health services. Of primary health-care facilities, 1,453 were surveyed. Facilities maintained between 84% and 97% of the expected outpatient services, except for Bangladesh, where 69% of the expected outpatient consultations were conducted between March 2020 and December 2021. For Burkina Faso, Chad, Guatemala, Guinea and Nigeria, critical infrastructure was the largest constraint in resilience capabilities (47%, 14%, 51%, 9% and 29% of facilities demonstrated capacity, respectively). Medical supplies and equipment were the largest constraints for Liberia and Malawi (15% and 48% of facilities demonstrating capacity, respectively). In Bangladesh, the largest constraint was workforce and staffing, where 44% of facilities experienced moderate to severe challenges with human resources during the pandemic. The largest constraints in facility resilience during COVID-19 were related to health systems building blocks. These challenges likely existed before the pandemic, suggesting the need for strategic investments and reforms in core capacities of comprehensive primary health-care systems to improve resilience to future shocks.


Assuntos
COVID-19 , Humanos , COVID-19/epidemiologia , Estudos Transversais , Países em Desenvolvimento , Instalações de Saúde , Assistência Ambulatorial
4.
J Chem Phys ; 156(19): 194110, 2022 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-35597663

RESUMO

The restricted active space spin-flip (RAS-SF) formalism is a particular form of single-reference configuration interaction that can describe some forms of strong correlation at a relatively low cost and which has recently been formulated for the description of charge-transfer excited states. Here, we introduce both equilibrium and nonequilibrium versions of a state-specific solvation correction for vertical transition energies computed using RAS-SF wave functions, based on the framework of a polarizable continuum model (PCM). Ground-state polarization is described using the solvent's static dielectric constant and in the nonequilibrium solvation approach that polarization is modified upon vertical excitation using the solvent's optical dielectric constant. Benchmark calculations are reported for well-studied models of photo-induced charge transfer, including naphthalene dimer, C2H4⋯C2F4, pentacene dimer, and perylene diimide (PDI) dimer, several of which are important in organic photovoltaic applications. For the PDI dimer, we demonstrate that the charge-transfer character of the excited states is enhanced in the presence of a low-dielectric medium (static dielectric constant ɛ0 = 3) as compared to a gas-phase calculation (ɛ0 = 1). This stabilizes mechanistic traps for singlet fission and helps to explain experimental singlet fission rates. We also examine the effects of nonequilibrium solvation on charge-separated states in an intramolecular singlet fission chromophore, where we demonstrate that the energetic ordering of the states changes as a function of solvent polarity. The RAS-SF + PCM methodology that is reported here provides a framework to study charge-separated states in solution and in photovoltaic materials.

5.
J Chem Phys ; 155(8): 084801, 2021 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-34470363

RESUMO

This article summarizes technical advances contained in the fifth major release of the Q-Chem quantum chemistry program package, covering developments since 2015. A comprehensive library of exchange-correlation functionals, along with a suite of correlated many-body methods, continues to be a hallmark of the Q-Chem software. The many-body methods include novel variants of both coupled-cluster and configuration-interaction approaches along with methods based on the algebraic diagrammatic construction and variational reduced density-matrix methods. Methods highlighted in Q-Chem 5 include a suite of tools for modeling core-level spectroscopy, methods for describing metastable resonances, methods for computing vibronic spectra, the nuclear-electronic orbital method, and several different energy decomposition analysis techniques. High-performance capabilities including multithreaded parallelism and support for calculations on graphics processing units are described. Q-Chem boasts a community of well over 100 active academic developers, and the continuing evolution of the software is supported by an "open teamware" model and an increasingly modular design.

6.
Eur J Obstet Gynecol Reprod Biol ; 249: 21-31, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32348948

RESUMO

Globally, a growing proportion of induced abortions are medical abortions. The procedure has been hailed as a revolutionary technology, which, according to experts, has the potential to transform women's experiences of abortion and the way abortion services are accessed. Noticeably absent in the discourse, however, are women's voices. More specifically, there is a lack of understanding about what shapes women's preferences for medical abortion and the challenges they experience in accessing the drugs for the procedure. We conducted a systematic review of the literature to draw attention to these important issues which exist, but are often embedded within research highlighting other dominating aspects of medical abortions. A comprehensive search of four databases - supplemented by searching reference sections of selected articles, tracking their citations, and hand searching special editions on medical abortion - was conducted. A total of 45 peer-reviewed studies met our inclusion criteria. The studies were assessed for quality and analyzed using a critical interpretive synthesis approach. The findings revealed significant variations in women's preferences for surgical versus medical abortions. Country-specific abortion laws, implementing protocols, side-effects, rates of failures, and the need to verify the abortion shaped women's preference for abortion methods. Overall, women who preferred medical abortions did so because they perceived it as a 'natural' and safe procedure that can be self-conducted at home, thereby reducing their dependency on the health system. However, women face significant barriers to medical abortion care. These include legal requirements around type of provider, site of service, need for follow-up, providers' limited knowledge of the procedure, and preferences for surgical abortions. Borderless internet-based services have enabled some women to circumvent these barriers. Our review suggests that medical abortions are used by women either in countries where the health system is fully supportive or where the health system is completely disengaged, usually due to restricted abortion laws. In those countries where abortions are legal but often difficult to access due to health system barriers, women tend to prefer surgical abortions.


Assuntos
Aborto Induzido/métodos , Aborto Induzido/psicologia , Preferência do Paciente/psicologia , Gestantes/psicologia , Abortivos/administração & dosagem , Feminino , Acessibilidade aos Serviços de Saúde , Humanos , Mifepristona/administração & dosagem , Misoprostol/administração & dosagem , Gravidez , Pesquisa Qualitativa
8.
Mol Phylogenet Evol ; 121: 121-131, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29305243

RESUMO

Molecular phylogenetic approaches have greatly improved our knowledge of the pattern and process of biological diversification across the globe; however, many regions remain poorly documented, even for well-studied vertebrate taxa. The Philippine archipelago, one of the least-studied 'biodiversity hotspots', is an ideal natural laboratory for investigating the factors driving diversification in an insular and geologically dynamic setting. We investigated the history and geography of diversification of the Philippine populations of a widespread montane bird, the White-browed Shortwing (Brachypteryx montana). Leveraging dense archipelago-wide sampling, we generated a multi-locus genetic dataset (one nuclear and two mtDNA markers), which we analyzed using phylogenetic, population genetic, and coalescent-based methods. Our results demonstrate that Philippine shortwings (1) likely colonized the Philippines from the Sunda Shelf to Mindanao in the late Miocene or Pliocene, (2) diversified across inter-island barriers into three divergent lineages during the Pliocene and early Pleistocene, (3) have not diversified within the largest island, Luzon, contrary to patterns observed in other montane taxa, and (4) colonized Palawan from the oceanic Philippines rather than from Borneo, challenging the assumption of Palawan functioning exclusively as a biogeographic extension of the Sunda Shelf. Additionally, our finding that divergent (c. 4.0 mya) lineages are coexisting in secondary sympatry on Mindanao without apparent gene flow suggests that the speciation process is likely complete for these shortwing lineages. Overall, these investigations provide insight into how topography and island boundaries influence diversification within remote oceanic archipelagos and echo the results of many other studies in demonstrating that taxonomic diversity continues to be underestimated in the Philippines.


Assuntos
Biodiversidade , Aves Canoras/genética , Animais , Teorema de Bayes , Calibragem , DNA Mitocondrial/genética , Genética Populacional , Geografia , Haplótipos/genética , Ilhas , Funções Verossimilhança , Filipinas , Filogenia , Análise de Sequência de DNA , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA