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1.
Cell ; 178(1): 44-59.e7, 2019 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-31104844

RESUMO

Hypothalamic Agrp neurons regulate food ingestion in adult mice. Whether these neurons are functional before animals start to ingest food is unknown. Here, we studied the functional ontogeny of Agrp neurons during breastfeeding using postnatal day 10 mice. In contrast to adult mice, we show that isolation from the nursing nest, not milk deprivation or ingestion, activated Agrp neurons. Non-nutritive suckling and warm temperatures blunted this effect. Using in vivo fiber photometry, neonatal Agrp neurons showed a rapid increase in activity upon isolation from the nest, an effect rapidly diminished following reunion with littermates. Neonates unable to release GABA from Agrp neurons expressed blunted emission of isolation-induced ultrasonic vocalizations. Chemogenetic overactivation of these neurons further increased emission of these ultrasonic vocalizations, but not milk ingestion. We uncovered important functional properties of hypothalamic Agrp neurons during mouse development, suggesting these neurons facilitate offspring-to-caregiver bonding.


Assuntos
Proteína Relacionada com Agouti/metabolismo , Comportamento Alimentar/fisiologia , Hipotálamo/citologia , Neurônios/metabolismo , Proteína Relacionada com Agouti/genética , Animais , Animais Recém-Nascidos , Ingestão de Alimentos/fisiologia , Comportamento Materno/fisiologia , Camundongos , Camundongos Knockout , Leite , Proteínas Proto-Oncogênicas c-fos/metabolismo , Isolamento Social , Comportamento de Sucção/fisiologia , Temperatura , Vocalização Animal/fisiologia , Ácido gama-Aminobutírico/metabolismo
2.
Nat Methods ; 20(11): 1769-1779, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37919419

RESUMO

Recent advancements in single-cell technologies allow characterization of experimental perturbations at single-cell resolution. While methods have been developed to analyze such experiments, the application of a strict causal framework has not yet been explored for the inference of treatment effects at the single-cell level. Here we present a causal-inference-based approach to single-cell perturbation analysis, termed CINEMA-OT (causal independent effect module attribution + optimal transport). CINEMA-OT separates confounding sources of variation from perturbation effects to obtain an optimal transport matching that reflects counterfactual cell pairs. These cell pairs represent causal perturbation responses permitting a number of novel analyses, such as individual treatment-effect analysis, response clustering, attribution analysis, and synergy analysis. We benchmark CINEMA-OT on an array of treatment-effect estimation tasks for several simulated and real datasets and show that it outperforms other single-cell perturbation analysis methods. Finally, we perform CINEMA-OT analysis of two newly generated datasets: (1) rhinovirus and cigarette-smoke-exposed airway organoids, and (2) combinatorial cytokine stimulation of immune cells. In these experiments, CINEMA-OT reveals potential mechanisms by which cigarette-smoke exposure dulls the airway antiviral response, as well as the logic that governs chemokine secretion and peripheral immune cell recruitment.


Assuntos
Citocinas , Filmes Cinematográficos
3.
Aggress Behav ; 50(1): e22119, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37936509

RESUMO

The study examined the relationship between mistrust and aggression from childhood to adulthood. The participants resided in Portugal and were tested during middle childhood (Mage = 7.5, SD = 0.81 years, n = 445, 240 male), preadolescence (Mage = 11.92, SD = 0.96 years, n = 431, 200 male), mid-adolescence (Mage = 14.70, SD = 0.91 years, n = 326, 201 male), late adolescence (Mage = 18.14, SD = 1.19 years, n = 410, 216 male), and adulthood (Mage = 26.56, SD = 1.13, years, n = 417, 197 male). Mothers reported the participants' mistrust during childhood and preadolescence on items from the Child Behavior Checklist. Aggression was assessed by standardized self-report measures at each age period. It was found that mistrust was associated with aggression during preadolescence and predicted changes in aggression to mid-adolescence and adulthood. The findings supported the conclusion that mistrust during preadolescence predisposes individuals to show aggression later in the life course.


Assuntos
Agressão , Mães , Feminino , Adolescente , Humanos , Criança , Masculino , Adulto Jovem , Estudos Longitudinais , Autorrelato , Portugal
4.
Mol Biol Rep ; 50(4): 3439-3450, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36757549

RESUMO

BACKGROUND: Megalocytiviruses (MCV) are double-stranded DNA viruses that infect fish. Two species within the genus are epidemiologically important for fish farming: red sea bream iridovirus (RSIV) and infectious spleen and kidney necrosis virus (ISKNV). The objective of this work was to study regions that allow the differentiation and correct diagnosis of RSIV and ISKNV. METHODS: The regions ORF450L, ORF342L, ORF077, and the intergenic region between ORF37 and ORF42R were sequenced and compared with samples from the database. RESULTS: The tree constructed using the sequencing of the PCR product Megalocytivirus. ORF077 separated the three major clades of MCV. RISV genotypes were well divided, but not ISKNV. All qPCRs tests showed acceptable repeatability values, that is, less than 5%. CONCLUSION: Two qPCRs for ISKNV detection and two for RSIV were considered suitable for use in the diagnosis and typing of MCV. The results of this study demonstrate the importance of an accurate evaluation of methodologies for the differentiation of MCV.


Assuntos
Infecções por Vírus de DNA , Doenças dos Peixes , Iridoviridae , Iridovirus , Animais , Iridoviridae/genética , Reação em Cadeia da Polimerase em Tempo Real , Infecções por Vírus de DNA/genética , Infecções por Vírus de DNA/veterinária , Filogenia
5.
Dis Aquat Organ ; 149: 25-32, 2022 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-35510818

RESUMO

The infectious spleen and kidney necrosis virus (ISKNV) belongs to the genus Megalocytivirus (MCV), a group of double-stranded DNA genome viruses. The aim of this study was to retrospectively analyze samples from suspected foci of MCV infection in freshwater fish in Brazil. Samples were collected from infected fish between 2017 and 2021. Phylogenetic analysis revealed 2 groups of MCV circulating in the country. A genetically homogeneous group formed a clade with ISKNV samples from different parts of the world. Only 2 of the sequences from the state of Goiás showed a small genetic distance when compared to the larger group in the same clade. This study describes the validation of 3 qPCR methods and the presence of MCV in Brazil since 2017, including a genotype not previously described.


Assuntos
Peixes-Gato , Ciclídeos , Infecções por Vírus de DNA , Doenças dos Peixes , Iridoviridae , Animais , Brasil/epidemiologia , Infecções por Vírus de DNA/epidemiologia , Infecções por Vírus de DNA/veterinária , Doenças dos Peixes/epidemiologia , Iridoviridae/genética , Filogenia , Estudos Retrospectivos
6.
Artigo em Inglês | MEDLINE | ID: mdl-35763175

RESUMO

This study aimed to (1) evaluate how population levels of anxiety and depression grow and correlate from middle childhood through early adulthood, and (2) determine whether sex, family socioeconomic status, parental education, academic achievement, learning disabilities, or externalizing symptoms predict anxiety and/or depression levels and growth trajectory. We used two longitudinal samples (N = 445, 448) of Portuguese children. Mean depression levels increased from mid-childhood through adolescence before stabilizing in early adulthood and were most strongly predicted by academic achievement and learning disabilities. Mean anxiety levels increased until adolescence before decreasing across early adulthood and were most strongly predicted by academic achievement, learning disabilities, and externalizing symptoms. Quadratic models of growth fit best for both depression and anxiety, and depression and anxiety growth trajectories were strongly correlated. Though anxiety and depression trajectories differ in pattern and predictors, the two are highly interrelated and pathways to comorbid anxiety and depression should be characterized.

7.
J Environ Manage ; 320: 115882, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-35952566

RESUMO

Decomposition of dairy cows' excreta on housing floor leads to ammonia and greenhouse gases production, yet factors affecting total emissions have not been fully disclosed. This work aimed to assess the impact of lactation stage, feeding system and sampling time on gaseous emission potential of cow's faeces and urine in laboratory chambers systems. Individual faeces and urine were collected from two groups of four cows, at peak and post peak lactation, from three commercial farms with distinct feeding systems: total mixed ration (TMR), total mixed ration plus concentrate at robot (TMR + robot), and total mixed ration plus concentrate in automatic feeders (TMR + AF). Samples were collected before a.m. (T8h), at middle day (T12h), and before p.m. (T17h) milking. In a laboratory chambers system, faeces and urine were mixed in a ratio of 1.7:1, and ammonia and greenhouse gases emissions were monitored during 48-h. Cumulative N-N2O emissions were the highest in TMR + robot system, post peak cows and sampling time T17h. An interaction between stage of lactation and sampling time was detected for N-NH3 and N-N2O (g/kg organic soluble N) emissions. Post peak cows also produced the highest cumulative N-NH3 emissions. Overall results contribute for the identification of specific on-farm strategies to reduce gaseous emissions from cows' excreta.


Assuntos
Amônia , Gases de Efeito Estufa , Ração Animal/análise , Animais , Bovinos , Indústria de Laticínios/métodos , Dieta/veterinária , Fazendas , Feminino , Lactação , Leite
8.
Arch Virol ; 166(1): 243-247, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33159590

RESUMO

Pseudocowpox is a zoonosis caused by pseudocowpox virus (PCPV), which mainly affects cows but can be an occupational disease of humans. The aim of the study was to validate a quantitative polymerase chain reaction (qPCR) assay for the detection of PCPV. The assay was able to detect up to 1000 copies of PCPV per µL in field samples, with a sensitivity of 80% and a specificity of 100%. We did not observe any cross-reactivity between PCPV-positive samples and samples that were positive for other genetically similar viruses. The repeatability and reproducibility were adequate according to parameters preestablished in official test validation manuals.


Assuntos
Reação em Cadeia da Polimerase/métodos , Infecções por Poxviridae/virologia , Vírus da Pseudovaríola das Vacas/genética , Animais , Bovinos , Doenças dos Bovinos/virologia , Humanos , Infecções por Poxviridae/veterinária , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Zoonoses/virologia
9.
Molecules ; 26(14)2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34299448

RESUMO

Robust and selective quantification methods are required to better analyze feed supplementation effectiveness with specific amino acids. In this work, a reversed-phase high-performance liquid chromatography method with fluorescence detection is proposed and validated for lysine quantification, one of the most limiting amino acids in ruminant nutrition and essential towards milk production. To assess and widen method applicability, different matrices were considered: namely Li2CO3 buffer (the chosen standard reaction buffer), phosphate buffer solution (to mimic media in cellular studies), and rumen inoculum. The method was validated for all three matrices and found to be selective, accurate (92% ± 2%), and precise at both the inter- and intra-day levels in concentrations up to 225 µM, with detection and quantification limits lower than 1.24 and 4.14 µM, respectively. Sample stability was evaluated when stored at room temperature, 4 °C, and -20 °C, showing consistency for up to 48 h regardless of the matrix. Finally, the developed method was applied in the quantification of lysine on real samples. The results presented indicate that the proposed method can be applied towards free lysine quantification in ruminant feeding studies and potentially be of great benefit to dairy cow nutrition supplementation and optimization.


Assuntos
Ração Animal/análise , Lisina/análise , Lisina/química , Aminoácidos/química , Animais , Bovinos , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/métodos , Suplementos Nutricionais/análise , Reprodutibilidade dos Testes , Ruminantes/metabolismo
10.
Arch Virol ; 165(8): 1843-1847, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32448993

RESUMO

Cocal virus (COCV) is one of the causative agents of vesicular stomatitis, presenting clinical signs indistinguishable from those caused by foot-and-mouth disease virus (FMDV). Therefore, the differentiation of these two viruses via laboratory diagnosis is essential. The objective of this study was to develop and validate a real-time quantitative PCR (RT-qPCR) protocol for the diagnosis of COCV directly from epithelial samples. The method developed had 97% accuracy at 3950 pfu and a repeatability error of 1.29%. RT-qPCR was able to distinguish COCV from other viruses that cause vesicular diseases, an important factor because seroneutralization may produce cross-reactivity between COCV and vesicular stomatitis Alagoas virus (VSAV). No epithelial sample originating from vesicular disease outbreaks between 2014 and 2018 in Brazil was positive for COCV.


Assuntos
Estomatite Vesicular/diagnóstico , Estomatite Vesicular/virologia , Vesiculovirus/genética , Animais , Brasil , Vírus de DNA/genética , Febre Aftosa/diagnóstico , Febre Aftosa/virologia , Vírus da Febre Aftosa/genética , RNA Viral/genética , Reação em Cadeia da Polimerase em Tempo Real/métodos
11.
Molecules ; 25(6)2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32183441

RESUMO

This work proposes a simple and easy-to-use flow-through system for the implementation of dynamic extractions, aiming at the evaluation of bioaccessible zinc and the characterization of leaching kinetics in dry dog food samples. The kinetic profile of Zn extraction was determined by flame atomic absorption spectroscopy and the results were fitted in an exponential function (R2 > 0.960) compatible with a two first-order reactions model. Values of fast leachable Zn ranged from 83 ± 1 to 313 ± 5 mg of Zn per kg of sample, with associated rate constants ranging from 0.162 ± 0.004 to 0.290 ± 0.014 min-1. Similar results were observed compared to the static batch extraction. The percentage of bioaccessible Zn ranged from 49.0 to 70.0%, with an average value of 58.2% in relation to total Zn content. Principal component analysis regarding the variables fast leachable Zn, associated rate constant, total Zn, and market segment, has shown that 84.6% of variance is explained by two components, where the second component (24.0%) presented loadings only for the fast leachable Zn and associated rate constant. The proposed method is suitable for the fast evaluation (<1 h) of leaching kinetics and bioaccessibility in dry dog food.


Assuntos
Zinco/química , Zinco/metabolismo , Ração Animal , Animais , Disponibilidade Biológica , Cães , Cinética , Compostos Orgânicos/química , Compostos Orgânicos/metabolismo , Análise de Componente Principal/métodos , Espectrofotometria Atômica/métodos
12.
J Clin Child Adolesc Psychol ; 48(4): 596-609, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-29364720

RESUMO

As societies become increasingly diverse, mental health professionals need instruments for assessing emotional, behavioral, and social problems in terms of constructs that are supported within and across societies. Building on decades of research findings, multisample alignment confirmatory factor analyses tested an empirically based 8-syndrome model on parent ratings across 30 societies and youth self-ratings across 19 societies. The Child Behavior Checklist for Ages 6-18 and Youth Self-Report for Ages 11-18 were used to measure syndromes descriptively designated as Anxious/Depressed, Withdrawn/Depressed, Somatic Complaints, Social Problems, Thought Problems, Attention Problems, Rule-Breaking Behavior, and Aggressive Behavior. For both parent ratings (N = 61,703) and self-ratings (N = 29,486), results supported aggregation of problem items into 8 first-order syndromes for all societies (configural invariance), plus the invariance of item loadings (metric invariance) across the majority of societies. Supported across many societies in both parent and self-ratings, the 8 syndromes offer a parsimonious phenotypic taxonomy with clearly operationalized assessment criteria. Mental health professionals in many societies can use the 8 syndromes to assess children and youths for clinical, training, and scientific purposes.


Assuntos
Pais/psicologia , Psicopatologia/métodos , Sociedades/normas , Adolescente , Criança , Feminino , Humanos , Masculino , Síndrome
13.
Food Microbiol ; 77: 85-92, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30297060

RESUMO

Oysters are important mariculture species worldwide. Because of their filter-feeding behaviors, oysters can accumulate microorganisms, including pathogens, from surrounding water and concentrate bacteria in high numbers. Rapid and suitable methods for quantification of Escherichia coli in oysters are necessary considering that oysters are perishable foods often consumed raw and some countries use E. coli as the regulatory limit. The objective of this study was to develop a qPCR method for quantification of E. coli in oysters. Additionally, different methods were evaluated for DNA extraction from oyster samples and the more reliable method was chosen. Primers and probe were designed targeting uidA gene of E. coli and shown to specifically amplify DNA from E. coli. Standard curves with bacterial DNA extracted from oysters samples artificially inoculated with E. coli were conducted. A good correlation was noticed when the qPCR method was compared to a culture method in oyster samples. This is the first report of a method exclusively developed for direct quantification of E. coli in oyster, the method showed to be suitable for quantification of E. coli in oysters and could be useful in routine analyses, as it requires less time than the culture method.


Assuntos
Carga Bacteriana/métodos , Crassostrea/microbiologia , Escherichia coli/isolamento & purificação , Reação em Cadeia da Polimerase em Tempo Real/métodos , Reação em Cadeia da Polimerase em Tempo Real/veterinária , Animais , Proteínas de Bactérias/genética , DNA Bacteriano/análise , Escherichia coli/genética , Genes Bacterianos/genética , Sensibilidade e Especificidade
14.
Virol J ; 15(1): 184, 2018 11 26.
Artigo em Inglês | MEDLINE | ID: mdl-30477549

RESUMO

BACKGROUND: Hevea brasiliensis is an important commercial crop due to the high quality of the latex it produces; however, little is known about viral infections in this plant. The only virus described to infect H. brasiliensis until now is a Carlavirus, which was described more than 30 years ago. Virus-derived small interfering RNA (vsiRNAs) are the product of the plant's antiviral defense triggered by dsRNA viral intermediates generated, during the replication cycle. These vsiRNAs are complementar to viral genomes and have been widely used to identify and characterize viruses in plants. METHODS: In the present study, we investigated the virome of leaf and sapwood samples from native H. brasiliensis trees collected in two geographic areas in the Brazilian Amazon. Small RNA (sRNA) deep sequencing and bioinformatic tools were used to assembly, identify and characterize viral contigs. Subsequently, PCR amplification techniques were performed to experimentally verify the presence of the viral sequences. Finally, the phylogenetic relationship of the putative new virus with related viral genomes was analyzed. RESULTS: Our strategy allowed the identification of 32 contigs with high similarity to viral reference genomes, from which 23 exhibited homology to viruses of the Tymoviridae family. The reads showed a predominant size distribution at 21 nt derived from both strands, which was consistent with the vsiRNAs profile. The presence and genome position of the viral contigs were experimentally confirmed using droplet digital PCR amplifications. A 1913 aa long fragment was obtained and used to infer the phylogenetic relationship of the putative new virus, which indicated that it is taxonomically related to the Grapevine fleck virus, genus Maculavirus. The putative new virus was named Hevea brasiliensis virus (HBrV) in reference to its host. CONCLUSION: The methodological strategy applied here proved to be efficient in detecting and confirming the presence of new viral sequences on a 'very difficult to manage' sample. This is the second time that viral sequences, that could be ascribed as a putative novel virus, associated to the rubber tree has been identified.


Assuntos
Hevea/virologia , Vírus de RNA/classificação , Vírus de RNA/isolamento & purificação , RNA Interferente Pequeno/genética , Perfilação da Expressão Gênica , Genoma Viral , Sequenciamento de Nucleotídeos em Larga Escala , Filogenia , Doenças das Plantas/virologia , Folhas de Planta/virologia , Reação em Cadeia da Polimerase , RNA Viral/genética , Análise de Sequência de RNA
15.
Phys Chem Chem Phys ; 20(24): 16712-16718, 2018 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-29878013

RESUMO

An important aspect concerning the performance of armchair graphene nanoribbons (AGNRs) as materials for conceiving electronic devices is related to the mobility of charge carriers in these systems. When several polarons are considered in the system, a quasi-particle wave function can be affected by that of its neighbor provided the two are close enough. As the overlap may affect the transport of the carrier, the question concerning how the density of polarons affect its mobility arises. In this work, we investigate such dependence for semiconducting AGNRs in the scope of nonadiabatic molecular dynamics. Our results unambiguously show an impact of the density on both the stability and average velocity of the quasi-particles. We have found a phase transition between regimes where increasing density stops inhibiting and starts promoting mobility; densities higher than 7 polarons per 45 Å present increasing mean velocity with increasing density. We have also established three different regions relating electric field and average velocity. For the lowest electric field regime, surpassing the aforementioned threshold results in overcoming the 0.3 Å fs-1 limit, thus representing a transition between subsonic and supersonic regimes. For the highest of the electric fields, density effects alone are responsible for a stunning difference of 1.5 Å fs-1 in the mean carrier velocity.

16.
J Phys Chem A ; 122(15): 3866-3872, 2018 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-29608859

RESUMO

The recombination dynamics of two oppositely charged bipolarons within a single polymer chain is numerically studied in the scope of a one-dimensional tight-binding model that considers electron-electron and electron-phonon (e-ph) interactions. By scanning among values of e-ph coupling and electric field, novel channels for the bipolaron recombination were yielded based on the interplay between these two parameters. The findings point to the formation of a compound species formed from the coupling between a bipolaron and an exciton. Depending on the electric field and e-ph coupling strengths, the recombination mechanism may yield two distinct products: a trapped (and almost neutral) or a moving (and partially charged) bipolaron-exciton. These results might enlighten the understanding of the electroluminescence processes in organic light-emitting devices.

17.
J Aging Soc Policy ; 30(5): 458-477, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29461933

RESUMO

The aging population has an impact on health, social, and economic issues in regard to individuals, communities, and organizations. The challenge for local policies in response to aging is to create sufficient resources to meet the population's needs, wishes, and rights as people age. Active aging constitutes one of the guiding perspectives on policies. Taking into account the local governance perspective, the Model for Aging Local Policies Analysis (MALPA) was created in order to convert the active aging paradigm into a practical approach, as a technique to evaluate and analyze local aging policies. In this research, the MALPA instrument was applied in two Portuguese communities (Coruche and Oeiras). The objective was to identify the intervention priorities of aging policies in both communities, determining whether the instrument can facilitate the development of proposals for the improvement of local aging policies. It was possible to evaluate the communities and programs, identifying the least appropriate policy actions regarding the intervention priorities. The results allowed us to identify 10 priorities about collaborative governance, involvement of the elderly in the policy-making process, lifelong learning, economic hardship, policies for all ages, isolated vulnerable and fragile groups, intergenerational contacts, safety in all policies, labor opportunities, and conditions and transport network improvement.


Assuntos
Envelhecimento , Formulação de Políticas , Política Pública , Idoso , Humanos , Portugal
18.
Eur Arch Psychiatry Clin Neurosci ; 267(2): 117-121, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27484978

RESUMO

A randomized controlled trial was conducted to assess the effects of exercise plus pharmacotherapy on monoamine neurotransmitters (dopamine, noradrenaline, adrenaline, serotonin) and cortisol levels. A total of 26 women with clinical depression were randomly assigned to one of the two groups: aerobic exercise plus pharmacotherapy or only pharmacotherapy. The exercise program consisted of aerobic exercise, 45-50 min/session, three times/week, for 16 weeks. The biological parameters were measured before and after the exercise program. Adding exercise to pharmacotherapy had no additional effects on monoamines and cortisol plasma levels. These data are preliminary outcomes from a small sample and should be replicated.


Assuntos
Depressão/sangue , Depressão/terapia , Dopamina/sangue , Epinefrina/sangue , Terapia por Exercício/métodos , Hidrocortisona/sangue , Norepinefrina/sangue , Serotonina/sangue , Adulto , Terapia Combinada , Depressão/tratamento farmacológico , Feminino , Humanos , Resultado do Tratamento
19.
J Chem Phys ; 146(14): 144903, 2017 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-28411599

RESUMO

The transport of polarons above the mobility threshold in organic and inorganic polymers is theoretically investigated in the framework of a one-dimensional tight-binding model that includes lattice relaxation. The computational approach is based on parameters for which the model Hamiltonian suitably describes different polymer lattices in the presence of external electric fields. Our findings show that, above critical field strengths, a dissociated polaron moves through the polymer lattice as a free electron performing Bloch oscillations. These critical electric fields are considerably smaller for inorganic lattices in comparison to organic polymers. Interestingly, for inorganic lattices, the free electron propagates preserving charge and spin densities' localization which is a characteristic of a static polaron. Moreover, in the turning points of the spatial Bloch oscillations, transient polaron levels are formed inside the band gap, thus generating a fully characterized polaron structure. For the organic case, on the other hand, no polaron signature is observed: neither in the shape of the distortion-those polaron profile signatures are absent-nor in the energy levels-as no such polaron levels are formed during the simulation. These results solve controversial aspects concerning Bloch oscillations recently reported in the literature and may enlighten the understanding about the charge transport mechanism in polymers above their mobility edge.

20.
Rev Esc Enferm USP ; 51: e03281, 2017 Dec 21.
Artigo em Português, Inglês | MEDLINE | ID: mdl-29267733

RESUMO

OBJECTIVE: Analyzing the frequency patterns of practicing sports, the stages of change phases and the pros and cons of decision-making balance in nursing students related to gender and which year of study they are in. METHOD: A cross-sectional, descriptive and exploratory study. RESULTS: 535 students of both genders participated in the study. An analysis of the results revealed that 27.6% of the students did not present any frequency of practicing sports; 55.3% of the students did not have a consistent or continuous habit of practicing sports; students overall exhibited a non-existing frequency of practicing sports at similar levels throughout the study cycle; male students presented similar percentages in their positioning in the precontemplation and contemplation stages throughout the study cycle; and throughout all the stages of change phases students showed higher values for pros over cons related to practicing sports. CONCLUSION: The results reinforce the relevance for implementing mechanisms for promoting and monitoring nursing students' involvement and regular participation in practicing sports.


Assuntos
Comportamentos Relacionados com a Saúde , Esportes , Estudantes de Enfermagem , Adolescente , Adulto , Estudos Transversais , Tomada de Decisões , Feminino , Humanos , Masculino , Estudantes de Enfermagem/psicologia , Adulto Jovem
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