Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 72
Filtrar
1.
ACS Appl Mater Interfaces ; 16(10): 12509-12520, 2024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-38415586

RESUMO

We report the use of Zr-based metal-organic frameworks (MOFs) MOF-545 and MOF-545(Cu) as supports to prepare catalysts with uniformly and highly dispersed Ni nanoparticles (NPs) for CO2 hydrogenation into CH4. In the first step, we studied the MOF support under catalytic conditions using operando diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, ex situ characterizations (PXRD, XPS, TEM, and EDX-element mapping), and DFT calculations. We showed that the high-temperature conditions undoubtedly confer a potential for catalytic functionality to the solids toward CH4 production, while no role of the Cu could be evidenced. The MOF was shown to be transformed into a catalytically active material, amorphized but still structured with dehydroxylated Zr-oxoclusters, in line with DFT calculations. In the second step, Ni@MOF-545 catalysts were prepared using either impregnation (IM) or double solvent (DS) methods, followed by a dry reduction (R) route under H2 to immobilize Ni NPs. The highest catalytic activity was obtained with the Ni@MOF-545 DS R catalyst (595 mmolCH4 gNi-1 h-1) with 100% CH4 selectivity and 60% CO2 conversion after ∼3 h. The higher catalytic activity of Ni@MOF-545 DS R is a result of much smaller (∼5 nm) and better dispersed Ni NPs than in the IM sample (20-40 nm), the latter exhibiting sintering. The advantages of the encapsulation of Ni NPs by the DS method and of the use of a MOF-545-based support are discussed, highlighting the interest of designing yet-unexplored Zr-based MOFs loaded with Ni NPs for CO2 hydrogenation.

2.
PLoS Comput Biol ; 20(1): e1011760, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38190390

RESUMO

The basic computations performed in the human early visual cortex are the foundation for visual perception. While we know a lot about these computations, a key missing piece is how the coding of visual features relates to our perception of the environment. To investigate visual feature coding, interactions, and their relationship to human perception, we investigated neural responses and perceptual similarity judgements to a large set of visual stimuli that varied parametrically along four feature dimensions. We measured neural responses using electroencephalography (N = 16) to 256 grating stimuli that varied in orientation, spatial frequency, contrast, and colour. We then mapped the response profiles of the neural coding of each visual feature and their interactions, and related these to independently obtained behavioural judgements of stimulus similarity. The results confirmed fundamental principles of feature coding in the visual system, such that all four features were processed simultaneously but differed in their dynamics, and there was distinctive conjunction coding for different combinations of features in the neural responses. Importantly, modelling of the behaviour revealed that every stimulus feature contributed to perceptual judgements, despite the untargeted nature of the behavioural task. Further, the relationship between neural coding and behaviour was evident from initial processing stages, signifying that the fundamental features, not just their interactions, contribute to perception. This study highlights the importance of understanding how feature coding progresses through the visual hierarchy and the relationship between different stages of processing and perception.


Assuntos
Córtex Visual , Percepção Visual , Humanos , Estimulação Luminosa/métodos , Percepção Visual/fisiologia , Eletroencefalografia , Córtex Visual/fisiologia , Mapeamento Encefálico
3.
Conscious Cogn ; 117: 103598, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38086154

RESUMO

Little is known about the perceptual characteristics of mental images nor how they vary across sensory modalities. We conducted an exhaustive survey into how mental images are experienced across modalities, mainly targeting visual and auditory imagery of a single stimulus, the letter "O", to facilitate direct comparisons. We investigated temporal properties of mental images (e.g. onset latency, duration), spatial properties (e.g. apparent location), effort (e.g. ease, spontaneity, control), movement requirements (e.g. eye movements), real-imagined interactions (e.g. inner speech while reading), beliefs about imagery norms and terminologies, as well as respondent confidence. Participants also reported on the five traditional senses and their prominence during thinking, imagining, and dreaming. Overall, visual and auditory experiences dominated mental events, although auditory mental images were superior to visual mental images on almost every metric tested except regarding spatial properties. Our findings suggest that modality-specific differences in mental imagery may parallel those of other sensory neural processes.


Assuntos
Imaginação , Sensação , Humanos , Percepção Visual , Imagens, Psicoterapia , Percepção Auditiva
4.
Quart J Polit Sci ; 18(3): 295-338, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38077161

RESUMO

Scholarship shows that Black immigrants to the US resist assimilation to reduce exposure to racial discrimination faced by native-born African Americans. But, not all Black immigrants are equally likely to be (mis)perceived as African American. We argue that immigrants who are likely to be misidentified as African American have incentives to reify ethnic boundaries as a form of protection against racial discrimination. We develop this argument from interviews and focus groups with African immigrants. We then use a lab experiment to measure rates of miscategorization and identify its correlates among African immigrants. Finally, we test our argument with a novel survey of Somalis, an immigrant population with two ethnic subgroups who differ in their likelihood of being miscategorized as African Americans. We show that this difference shapes the degree of resistance to assimilation. These findings improve our understanding of the relationship between racial discrimination and incentives for Black immigrants to resist assimilation.

5.
J Clin Transl Sci ; 7(1): e213, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38028347

RESUMO

Background: The Fibrosis-4 (FIB-4) index, a simple index that includes age, liver enzymes, and platelet count has been studied as a tool to identify patients at a risk of requiring mechanical ventilation due to its high negative predictive value. It is unknown if FIB-4 remains useful to predict the severity of respiratory disease requiring mechanical ventilation amongst new Coronavirus disease 2019 (COVID-19) variants and whether a relationship also exists between FIB-4 and 30-day mortality. The main objective was to determine if FIB-4 can predict mechanical ventilation requirements and 30-day mortality from COVID-19 across variants including Alpha, Delta, and Omicron. Methods: This was a population-based, retrospective cohort analysis of 232,364 hospitalized patients in the National COVID-19 Cohort Collaborative between the age of 18-90 who tested positive for COVID-19 between April 27, 2020 and June 25, 2022. The primary outcome was association between FIB-4 and need for mechanical ventilation. Secondary measures included the association of FIB-4 with 30-day mortality. Results: A FIB-4 > 2.67 had 1.8 times higher odds of requiring mechanical ventilation across all variants of COVID-19 (OR 1.81; 95% CI: [1.76, 1.86]). The area under the ROC curve showed high diagnostic accuracy with values ranging between 0.79 (Omicron wave) and 0.97 (delta wave). Increased FIB-4 was associated with 30-day mortality across the variates. Conclusion: The FIB-4 was consistently associated with both increased utilization of mechanical ventilation and 30-day mortality among COVID-19 patients across all waves in both adjusted and unadjusted models. This provides a simple tool for risk-stratification for front-line health care professionals.

6.
Violence Against Women ; : 10778012231214772, 2023 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-37981791

RESUMO

This article explores "how do victims-survivors of gender-based violence (GBV) experience and perceive justice?" based on interviews with 251 victims-survivors with experience of different types of GBV and criminal, civil, and family justice systems. Victims-survivors were found to have multiple perceptions of justice, related to different points in their journey following abuse and regarding individual, community, and societal responses. Perceptions relate to accountability; fairness in outcome and process; protection from future harm; recognition; agency; empowerment; affective justice; reparation; and social transformation. Current understandings of justice in legislative and policy approaches reproduce the "justice gap" by failing to take account of how survivors themselves understand and demand justice.

7.
Neurosci Conscious ; 2023(1): niad018, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37621984

RESUMO

Mental imagery is a process by which thoughts become experienced with sensory characteristics. Yet, it is not clear why mental images appear diminished compared to veridical images, nor how mental images are phenomenologically distinct from hallucinations, another type of non-veridical sensory experience. Current evidence suggests that imagination and veridical perception share neural resources. If so, we argue that considering how neural representations of externally generated stimuli (i.e. sensory input) and internally generated stimuli (i.e. thoughts) might interfere with one another can sufficiently differentiate between veridical, imaginary, and hallucinatory perception. We here use a simple computational model of a serially connected, hierarchical network with bidirectional information flow to emulate the primate visual system. We show that modelling even first approximations of neural competition can more coherently explain imagery phenomenology than non-competitive models. Our simulations predict that, without competing sensory input, imagined stimuli should ubiquitously dominate hierarchical representations. However, with competition, imagination should dominate high-level representations but largely fail to outcompete sensory inputs at lower processing levels. To interpret our findings, we assume that low-level stimulus information (e.g. in early visual cortices) contributes most to the sensory aspects of perceptual experience, while high-level stimulus information (e.g. towards temporal regions) contributes most to its abstract aspects. Our findings therefore suggest that ongoing bottom-up inputs during waking life may prevent imagination from overriding veridical sensory experience. In contrast, internally generated stimuli may be hallucinated when sensory input is dampened or eradicated. Our approach can explain individual differences in imagery, along with aspects of daydreaming, hallucinations, and non-visual mental imagery.

8.
Annu Rev Vis Sci ; 9: 313-335, 2023 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-36889254

RESUMO

Patterns of brain activity contain meaningful information about the perceived world. Recent decades have welcomed a new era in neural analyses, with computational techniques from machine learning applied to neural data to decode information represented in the brain. In this article, we review how decoding approaches have advanced our understanding of visual representations and discuss efforts to characterize both the complexity and the behavioral relevance of these representations. We outline the current consensus regarding the spatiotemporal structure of visual representations and review recent findings that suggest that visual representations are at once robust to perturbations, yet sensitive to different mental states. Beyond representations of the physical world, recent decoding work has shone a light on how the brain instantiates internally generated states, for example, during imagery and prediction. Going forward, decoding has remarkable potential to assess the functional relevance of visual representations for human behavior, reveal how representations change across development and during aging, and uncover their presentation in various mental disorders.


Assuntos
Envelhecimento , Encéfalo , Humanos , Aprendizado de Máquina
9.
Sci Immunol ; 7(76): eabm2084, 2022 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-36206356

RESUMO

Understanding how follicular helper T cells (TFH) regulate the specialization, maturation, and differentiation of adaptive B cell immunity is crucial for developing durable high-affinity immune protection. Using indexed single-cell molecular strategies, we reveal a skewed intraclonal assortment of higher-affinity T cell receptors and the distinct molecular programming of the localized TFH compartment compared with emigrant conventional effector TH cells. We find a temporal shift in B cell receptor class switch, which permits identification of inflammatory and anti-inflammatory modules of transcriptional programming that subspecialize TFH function before and during the germinal center (GC) reaction. Late collapse of this local primary GC reaction reveals a persistent post-GC TFH population that discloses a putative memory TFH program. These studies define subspecialized antigen-specific TFH transcriptional programs that progressively change with antibody class-specific evolution of high-affinity B cell immunity and a memory TFH transcriptional program that emerges upon local GC resolution.


Assuntos
Células T Auxiliares Foliculares , Linfócitos T Auxiliares-Indutores , Antígenos , Centro Germinativo , Isotipos de Imunoglobulinas , Receptores de Antígenos de Linfócitos B
10.
Neuroimage ; 261: 119517, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-35901917

RESUMO

The ability to perceive moving objects is crucial for threat identification and survival. Recent neuroimaging evidence has shown that goal-directed movement is an important element of object processing in the brain. However, prior work has primarily used moving stimuli that are also animate, making it difficult to disentangle the effect of movement from aliveness or animacy in representational categorisation. In the current study, we investigated the relationship between how the brain processes movement and aliveness by including stimuli that are alive but still (e.g., plants), and stimuli that are not alive but move (e.g., waves). We examined electroencephalographic (EEG) data recorded while participants viewed static images of moving or non-moving objects that were either natural or artificial. Participants classified the images according to aliveness, or according to capacity for movement. Movement explained significant variance in the neural data over and above that of aliveness, showing that capacity for movement is an important dimension in the representation of visual objects in humans.


Assuntos
Mapeamento Encefálico , Eletroencefalografia , Encéfalo , Humanos , Movimento , Reconhecimento Visual de Modelos , Estimulação Luminosa
11.
Vision Res ; 199: 108079, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35749833

RESUMO

Can we trust our eyes? Until recently, we rarely had to question whether what we see is indeed what exists, but this is changing. Artificial neural networks can now generate realistic images that challenge our perception of what is real. This new reality can have significant implications for cybersecurity, counterfeiting, fake news, and border security. We investigated how the human brain encodes and interprets realistic artificially generated images using behaviour and brain imaging. We found that we could reliably decode AI generated faces using people's neural activity. However, while at a group level people performed near chance classifying real and realistic fakes, participants tended to interchange the labels, classifying real faces as realistic fakes and vice versa. Understanding this difference between brain and behavioural responses may be key in determining the 'real' in our new reality. Stimuli, code, and data for this study can be found at https://osf.io/n2z73/.


Assuntos
Mapeamento Encefálico , Encéfalo , Inteligência Artificial , Mapeamento Encefálico/métodos , Humanos
12.
Proc Natl Acad Sci U S A ; 119(25): e2121260119, 2022 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-35704755

RESUMO

Antibodies are produced across multiple isotypes with distinct properties that coordinate initial antigen clearance and confer long-term antigen-specific immune protection. Here, we interrogate the molecular programs of isotype-specific murine plasma cells (PC) following helper T cell-dependent immunization and within established steady-state immunity. We developed a single-cell-indexed and targeted molecular strategy to dissect conserved and divergent components of the rapid effector phase of antigen-specific IgM+ versus inflammation-modulating programs dictated by type 1 IgG2a/b+ PC differentiation. During antibody affinity maturation, the germinal center (GC) cycle imparts separable programs for post-GC type 2 inhibitory IgG1+ and type 1 inflammatory IgG2a/b+ PC to direct long-term cellular function. In the steady state, two subsets of IgM+ and separate IgG2b+ PC programs clearly segregate from splenic type 3 IgA+ PC programs that emphasize mucosal barrier protection. These diverse isotype-specific molecular pathways of PC differentiation control complementary modules of antigen clearance and immune protection that could be selectively targeted for immunotherapeutic applications and vaccine design.


Assuntos
Diferenciação Celular , Centro Germinativo , Plasmócitos , Animais , Antígenos , Imunoglobulina G/genética , Imunoglobulina M , Camundongos , Plasmócitos/citologia , Análise de Célula Única , Linfócitos T Auxiliares-Indutores
13.
Sci Rep ; 12(1): 6968, 2022 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-35484363

RESUMO

Selective attention prioritises relevant information amongst competing sensory input. Time-resolved electrophysiological studies have shown stronger representation of attended compared to unattended stimuli, which has been interpreted as an effect of attention on information coding. However, because attention is often manipulated by making only the attended stimulus a target to be remembered and/or responded to, many reported attention effects have been confounded with target-related processes such as visual short-term memory or decision-making. In addition, attention effects could be influenced by temporal expectation about when something is likely to happen. The aim of this study was to investigate the dynamic effect of attention on visual processing using multivariate pattern analysis of electroencephalography (EEG) data, while (1) controlling for target-related confounds, and (2) directly investigating the influence of temporal expectation. Participants viewed rapid sequences of overlaid oriented grating pairs while detecting a "target" grating of a particular orientation. We manipulated attention, one grating was attended and the other ignored (cued by colour), and temporal expectation, with stimulus onset timing either predictable or not. We controlled for target-related processing confounds by only analysing non-target trials. Both attended and ignored gratings were initially coded equally in the pattern of responses across EEG sensors. An effect of attention, with preferential coding of the attended stimulus, emerged approximately 230 ms after stimulus onset. This attention effect occurred even when controlling for target-related processing confounds, and regardless of stimulus onset expectation. These results provide insight into the effect of feature-based attention on the dynamic processing of competing visual information.


Assuntos
Atenção , Motivação , Atenção/fisiologia , Sinais (Psicologia) , Eletroencefalografia , Humanos , Percepção Visual/fisiologia
14.
Chemistry ; 28(28): e202200217, 2022 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-35315975

RESUMO

We report two new FeIII complexes [L1 FeIII (H2 O)](OTf)2 and [L2 FeIII (OTf)], obtained by replacing pyridines by phenolates in a known non-heme aminopyridine iron complex. While the original, starting aminopyridine [(L5 2 )FeII (MeCN)](PF6 ) complex is stable in air, the potentials of the new FeIII/II couples decrease to the point that [L2 FeII ] spontaneously reduces O2 to superoxide. We used it as an O2 activator in an electrochemical setup, as its presence allows to generate superoxide at a much more accessible potential (>500 mV gain). Our aim was to achieve substrate oxidation via the reductive activation of O2 . While L2 FeIII (OTf) proved to be a good O2 activator but a poor oxidation system, its association with another complex (TPEN)FeII (PF6 )2 generates a complementary tandem couple for electro-assisted oxidation of substrates, working at a very accessible potential: upon reduction, L2 FeIII (OTf) activates O2 to superoxide and transfers it to (TPEN)FeII (PF6 )2 leading in fine to the oxidation of thioanisole.


Assuntos
Compostos Férricos , Superóxidos , Aminopiridinas , Compostos Férricos/química , Compostos Ferrosos/química , Ferro , Oxirredução , Oxigênio/química , Sulfetos
15.
Sci Data ; 9(1): 3, 2022 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-35013331

RESUMO

The neural basis of object recognition and semantic knowledge has been extensively studied but the high dimensionality of object space makes it challenging to develop overarching theories on how the brain organises object knowledge. To help understand how the brain allows us to recognise, categorise, and represent objects and object categories, there is a growing interest in using large-scale image databases for neuroimaging experiments. In the current paper, we present THINGS-EEG, a dataset containing human electroencephalography responses from 50 subjects to 1,854 object concepts and 22,248 images in the THINGS stimulus set, a manually curated and high-quality image database that was specifically designed for studying human vision. The THINGS-EEG dataset provides neuroimaging recordings to a systematic collection of objects and concepts and can therefore support a wide array of research to understand visual object processing in the human brain.


Assuntos
Encéfalo/fisiologia , Eletroencefalografia , Reconhecimento Psicológico , Percepção Visual , Adolescente , Adulto , Feminino , Humanos , Masculino , Semântica , Adulto Jovem
16.
STAR Protoc ; 3(1): 101064, 2022 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-35005646

RESUMO

Adaptive T and B lymphocytes expand, respond, and persist across a multitude of separable cell differentiation states. Small compartments of these cells present defined cell surface phenotype, but express potentially divergent immune functions. Here, we use high resolution flow cytometry to provide direct access to rare lymphocyte subpopulations for evaluation of steady-state or reactive transcriptional programs. We sort and index single cells by phenotype in 384-well format for quantification of targeted gene amplification through RNA sequencing (single cell qtSEQ). For complete details on the use and execution of this profile, please refer to Dufaud et al. (2021).


Assuntos
Linfócitos B , Subpopulações de Linfócitos , Citometria de Fluxo , Contagem de Linfócitos , Análise de Sequência de RNA
17.
J Cogn Neurosci ; 34(4): 639-654, 2022 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-35061019

RESUMO

The human brain is extremely flexible and capable of rapidly selecting relevant information in accordance with task goals. Regions of frontoparietal cortex flexibly represent relevant task information such as task rules and stimulus features when participants perform tasks successfully, but less is known about how information processing breaks down when participants make mistakes. This is important for understanding whether and when information coding recorded with neuroimaging is directly meaningful for behavior. Here, we used magnetoencephalography to assess the temporal dynamics of information processing and linked neural responses with goal-directed behavior by analyzing how they changed on behavioral error. Participants performed a difficult stimulus-response task using two stimulus-response mapping rules. We used time-resolved multivariate pattern analysis to characterize the progression of information coding from perceptual information about the stimulus, cue and rule coding, and finally, motor response. Response-aligned analyses revealed a ramping up of perceptual information before a correct response, suggestive of internal evidence accumulation. Strikingly, when participants made a stimulus-related error, and not when they made other types of errors, patterns of activity initially reflected the stimulus presented, but later reversed, and accumulated toward a representation of the "incorrect" stimulus. This suggests that the patterns recorded at later time points reflect an internally generated stimulus representation that was used to make the (incorrect) decision. These results illustrate the orderly and overlapping temporal dynamics of information coding in perceptual decision-making and show a clear link between neural patterns in the late stages of processing and behavior.


Assuntos
Mapeamento Encefálico , Objetivos , Encéfalo/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética , Lobo Parietal/fisiologia , Estimulação Luminosa/métodos , Tempo de Reação/fisiologia
18.
Int J Offender Ther Comp Criminol ; 66(16): 1796-1820, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-34096354

RESUMO

This study examines the relationship between general offending and intimate partner violence (IPV) perpetration in young adulthood, using a Dutch longitudinal study. Young adults were followed over four waves, and self-reported data on general offending, IPV perpetration, and a number of individual characteristics were collected. Results of random effects models demonstrated that young adults involved in more diverse offending behavior reported higher levels of different types of IPV perpetration, even when individual factors were taken into account. Moreover, logistic regression analyses showed that general offending was also related to an increased likelihood of continuity in IPV perpetration. Taken together, the findings indicate that it is useful to view IPV perpetration as part of a broader criminal career.


Assuntos
Violência por Parceiro Íntimo , Adulto Jovem , Humanos , Adulto , Estudos Longitudinais , Fatores de Risco , Autorrelato , Etnicidade
19.
J Interpers Violence ; 37(3-4): 1179-1205, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-32456523

RESUMO

This study examined how patterns in general offending relate to the occurrence of and likelihood of persistence in intimate partner violence (IPV) perpetration in young adulthood. The study used longitudinal data from the cohort of 18 year olds from the Project on Human Development in Chicago Neighborhoods study. Self-reported offending was measured in all three waves, and data on IPV were collected in Waves 1 and 3. Group-based trajectory modeling identified three distinct general offending trajectory groups: non-offenders, low-rate offenders, and high-rate offenders. The majority of respondents engaged in psychological IPV perpetration, and half of all young adults reported physical IPV, but prevalence rates decreased over the waves. Binary logistic regression analyses showed that those involved in offending, especially those who showed a diverse offending pattern, were at increased risk of perpetrating psychological and (severe) physical IPV, as well as to show persistence in the different forms of IPV perpetration. The findings highlight an important overlap between general crime and IPV perpetration. In recognition that IPV is often part of a broader pattern of antisocial behavior, interventions should focus on interrupting the criminal careers of all young offenders to reduce the prevalence and harms of IPV.


Assuntos
Criminosos , Violência por Parceiro Íntimo , Adulto , Chicago/epidemiologia , Humanos , Prevalência , Fatores de Risco , Autorrelato , Adulto Jovem
20.
Front Hum Neurosci ; 15: 682661, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34305552

RESUMO

A large number of papers in Computational Cognitive Neuroscience are developing and testing novel analysis methods using one specific neuroimaging dataset and problematic experimental stimuli. Publication bias and confirmatory exploration will result in overfitting to the limited available data. We highlight the problems with this specific dataset and argue for the need to collect more good quality open neuroimaging data using a variety of experimental stimuli, in order to test the generalisability of current published results, and allow for more robust results in future work.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA