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1.
J Psychopharmacol ; 38(5): 432-457, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38742761

RESUMEN

BACKGROUND: Therapeutic and salutogenic effects of psychedelic drugs have been attributed to psychotherapeutic or psychotherapy-like processes that can unfold during the acute psychedelic experience and beyond. Currently, there are no psychometric instruments available to comprehensively assess psychotherapeutic processes (as conceptualized by empirical psychotherapy research) in the context of psychedelic experiences. AIMS: We report the initial validation of the General Change Mechanisms Questionnaire (GCMQ), a self-report instrument designed to measure five empirically established general change mechanisms (GCMs) of psychotherapy-(1) resource activation, (2) therapeutic relationship, (3) problem actuation, (4) clarification, and (5) mastery-in the context of psychedelic experiences. METHODS: An online survey in a sample of 1153 English-speaking and 714 German-speaking psychedelic users was conducted to evaluate simultaneously developed English- and German-language versions of the GCMQ. RESULTS: The theory-based factor structure was confirmed. The five GCMQ scales showed good internal consistency. Evidence for convergent validity with external measures was obtained. Significant associations with different settings and with therapeutic, hedonic, and escapist use motives confirmed the hypothesized context dependence of GCM-related psychedelic experiences. Indicating potential therapeutic effects, the association between cumulative stressful life events and well-being was significantly moderated by resource activation, clarification, and mastery. Factor mixture modeling revealed five distinct profiles of GCM-related psychedelic experiences. CONCLUSION: Initial testing indicates that the GCMQ is a valid and reliable instrument that can be used in future clinical and nonclinical psychedelic research. The five identified profiles of GCM-related experiences may be relevant to clinical uses of psychedelics and psychedelic harm reduction.


Asunto(s)
Alucinógenos , Psicometría , Humanos , Alucinógenos/uso terapéutico , Adulto , Femenino , Masculino , Encuestas y Cuestionarios/normas , Adulto Joven , Persona de Mediana Edad , Procesos Psicoterapéuticos , Reproducibilidad de los Resultados , Autoinforme , Psicoterapia/métodos , Adolescente
2.
Front Psychol ; 15: 1382483, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38751764

RESUMEN

Introduction: We all experience occasional self-control failures (SCFs) in our daily lives, where we enact behaviors that stand in conflict with our superordinate or long-term goals. Based on the assumption that SCFs share common underlying mechanisms with addictive disorders, we tested the hypothesis that a generally higher susceptibility to daily SCFs predicts more addictive behavior, or vice versa. Methods: At baseline, 338 individuals (19-27 years, 59% female) from a community sample participated in multi-component assessments. These included among others (1) a clinical interview on addictive behaviors (quantity of use, frequency of use, DSM-5 criteria; n = 338) and (2) ecological momentary assessment of SCFs (n = 329, 97%). At the 3-year and 6 year follow-up, participation rates for both assessment parts were 71% (n = 240) and 50% (n = 170), respectively. Results: Controlling for age, gender, IQ, and baseline addiction level, random-intercept cross-lagged panel models revealed that participants who reported more SCFs also showed pronounced addictive behavior at the between-person level, but we found no evidence of a predictive relationship at the within-person level over time. Discussion: A higher rate of SCFs is associated with more addictive behavior, while there is no evidence of an intraindividual predictive relationship. Novel hypotheses suggested by additional exploratory results are that (1) only addiction-related SCFs in daily life are early markers of an escalation of use and thus for addictive disorders and that (2) an explicit monitoring of SCFs increases self-reflection and thereby promotes the mobilization of cognitive control in response to goal-desire conflicts.

3.
Lancet Psychiatry ; 11(3): 231-236, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38101439

RESUMEN

Treatment of psychiatric disorders with psychedelic substances represents one of the most promising current treatment approaches in psychiatry. Since its inception in the 1950s, therapy with psychedelics has been conceptualised as psychedelic-assisted psychotherapy-ie, a form of psychotherapy that uses the profound biological effects of this class of substances as a catalyst for changing thinking, emotions, and behaviour. In this view, the psychotherapy component of the treatment is considered as being of the utmost importance for both the safety and efficacy of the therapy. This conceptualisation has been challenged by the idea that the latest clinical studies suggest that the potential therapeutic effects of psychedelics must be attributed solely to the substance itself, with no role for psychotherapy. Here, accompaniment by therapists is understood as mere psychological support, to maintain the safety of the substance administration. In this Personal View, we contrast these two views and argue that the characterisation of treatment with psychedelics as a biological intervention (with psychological support as a purely safety-related component) represents an outdated and reductionistic dualism that has dominated psychiatric treatment and research for far too long. This discussion has important implications for the study and the regulation of these compounds.


Asunto(s)
Alucinógenos , Trastornos Mentales , Psiquiatría , Humanos , Alucinógenos/uso terapéutico , Psicoterapia , Trastornos Mentales/tratamiento farmacológico , Emociones
4.
Sci Rep ; 13(1): 13051, 2023 Aug 11.
Artículo en Inglés | MEDLINE | ID: mdl-37567960

RESUMEN

Neutron spin echo spectroscopy is a high resolution inelastic neutron scattering method probing nanosecond dynamics. It is well suited to study the atomistic motion in polymer systems and contributes to our understanding of viscoelasticity. However, for samples under shear, or moving samples in general, Doppler scattering has to be considered. We compare the measured phase shift and depolarisation due to Doppler scattering from a rotating graphite disk to numerical and analytical calculations and find excellent agreement. This allows to take into account Doppler scattering during the data processing and makes longer Fourier times as well as higher shear rates and Q ranges possible with neutron spin echo spectroscopy, enabling for example the study of polymers under high shear.

5.
Rev Sci Instrum ; 94(3): 035104, 2023 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-37012801

RESUMEN

We present a new analytical instrument for studying the optical properties of materials in different gaseous environments at room and controlled elevated temperatures. The system consists of a vacuum chamber, which is equipped with temperature and pressure controllers, a heating band, and a residual gas analyzer and is connected to a gas feeding line via a leak valve. Two transparent view ports located around a sample holder allow for optical transmission and pump-probe spectroscopy using an external optical setup. The capabilities of the setup are demonstrated by conducting two experiments. In the first experiment, we study the photodarkening and bleaching kinetics of photochromic oxygen-containing yttrium hydride thin films illuminated in ultra high-vacuum and correlate it with changes in partial pressures inside the vacuum chamber. In the second study, we investigate changes in the optical properties of a 50 nm V film upon hydrogen absorption.

6.
ACS Appl Mater Interfaces ; 15(3): 3772-3780, 2023 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-36625710

RESUMEN

Arrays of nanoparticle-supported lipid bilayers (nanoSLB) are lipid-coated nanopatterned interfaces that provide a platform to study curved model biological membranes using surface-sensitive techniques. We combined scattering techniques with direct imaging, to gain access to sub-nanometer scale structural information on stable nanoparticle monolayers assembled on silicon crystals in a noncovalent manner using a Langmuir-Schaefer deposition. The structure of supported lipid bilayers formed on the nanoparticle arrays via vesicle fusion was investigated using a combination of grazing incidence X-ray and neutron scattering techniques complemented by fluorescence microscopy imaging. Ordered nanoparticle assemblies were shown to be suitable and stable substrates for the formation of curved and fluid lipid bilayers that retained lateral mobility, as shown by fluorescence recovery after photobleaching and quartz crystal microbalance measurements. Neutron reflectometry revealed the formation of high-coverage lipid bilayers around the spherical particles together with a flat lipid bilayer on the substrate below the nanoparticles. The presence of coexisting flat and curved supported lipid bilayers on the same substrate, combined with the sub-nanometer accuracy and isotopic sensitivity of grazing incidence neutron scattering, provides a promising novel approach to investigate curvature-dependent membrane phenomena on supported lipid bilayers.


Asunto(s)
Membrana Dobles de Lípidos , Nanopartículas , Membrana Dobles de Lípidos/química , Rayos X , Incidencia , Neutrones
7.
Fortschr Neurol Psychiatr ; 91(3): 80-87, 2023 Mar.
Artículo en Alemán | MEDLINE | ID: mdl-35724682

RESUMEN

OBJECTIVE: In recent years, studies investigating the use of psilocybin to treat mental disorders have shown promising results. In this context, this online survey investigated attitudes of trained psychiatrists and psychotherapists towards psilocybin and psilocybin-assisted therapies. MATERIALS AND METHODS: A total of 530 valid responses from individuals with suitable job profiles were collected in this online survey. Statistical analysis was used to identify relevant predictors of attitude measures. RESULTS: The opinions of experts in the treatment of mental disorders with psilocybin and psilocybin-assisted therapies varied widely, and the level of knowledge of the participants to some extent was low. A large number of participants considered treatment of mental disorders with psilocybin to be promising and treatment of depression with psilocybin was seen as promising by the majority of the participants. The results of this study suggest that a higher level of knowledge about psilocybin is associated with more optimistic views about its use in a therapeutic setting. Having additional scientific information led in some cases to more optimistic attitudes towards psilocybin and the use of psilocybin in the treatment of mental disorders. CONCLUSION: If the scientific and public discourse on psilocybin continues to grow in the future, changes in the attitudes of psychotherapists and psychiatrists can be expected.


Asunto(s)
Alucinógenos , Trastornos Mentales , Humanos , Psilocibina/uso terapéutico , Salud Mental , Alucinógenos/uso terapéutico , Trastornos Mentales/tratamiento farmacológico , Trastornos Mentales/psicología , Actitud
8.
BMC Psychol ; 10(1): 233, 2022 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-36243742

RESUMEN

BACKGROUND: Excessive alcohol consumption and alcohol use disorders (AUD) are among the leading preventable causes of premature morbidity and mortality and are considered a major public health concern. In order to reduce the individual and societal burden of excessive alcohol use, it is crucial to identify high-risk individuals at earlier stages and to provide effective interventions to prevent further progression. Stressful experiences are important risk factors for excessive alcohol consumption and AUDs. However, the underlying biological and psychological mechanisms are still poorly understood. METHODS: The project "Underlying mechanisms in the relationship between stress and alcohol consumption in regular and risky drinkers (MESA)" is a randomized controlled study that started in December 2018 and is conducted in a laboratory setting, which aims to identify moderators and mediators of the relationship between acute stress and alcohol consumption among regular and risky drinkers. Regular and risky drinkers are randomly assigned to a stress induction or a control condition. Several processes that may mediate (emotional distress, endocrine and autonomic stress reactivity, impulsivity, inhibitory control, motivational sensitization) or moderate (trait impulsivity, childhood maltreatment, basal HPA-axis activity) the relation between stress and alcohol consumption are investigated. As primary dependent variable, the motivation to consume alcohol following psychosocial stress is measured. DISCUSSION: The results of this study could help to provide valuable targets for future research on tailored interventions to prevent stress-related alcohol consumption.


Asunto(s)
Alcoholismo , Consumo de Bebidas Alcohólicas/psicología , Alcoholismo/psicología , Etanol , Humanos , Conducta Impulsiva , Motivación
9.
Psychopharmacology (Berl) ; 239(11): 3507-3524, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36190537

RESUMEN

RATIONALE: Although there is evidence that impaired executive functioning plays a role in addictive behavior, the longitudinal relationship between the two remains relatively unknown. OBJECTIVES: In a prospective-longitudinal community study, we tested the hypothesis that lower executive functioning is associated with more addictive behavior at one point in time and over time. METHODS: Three hundred and thirty-eight individuals (19-27 years, 59% female) from a random community sample were recruited into three groups: addictive disorders related to substances (n = 100) or to behaviors (n = 118), or healthy controls (n = 120). At baseline, participants completed nine executive function tasks from which a latent variable of general executive functioning (GEF) was derived. Addictive behavior (i.e., quantity and frequency of use, and number of DSM-5 criteria met) were assessed using standardized clinical interviews at baseline and three annual follow-ups. The trajectories of addictive behaviors were examined using latent growth curve modeling. RESULTS: At baseline, we found weak to no evidence of an associations between GEF and addictive behavior. We found evidence for an association between a lower GEF at baseline and a higher increase in the quantity of use and a smaller decrease in frequency of use over time, but no evidence for an association with an increase in the number of DSM-5 criteria met. CONCLUSIONS: Lower EFs appear to lead to a continuing loss of control over use, whereas addictive disorders may develop secondarily after a long period of risky use. Previous etiological models assuming lower EF as a direct vulnerability factor for addictive disorders need to be refined.


Asunto(s)
Conducta Adictiva , Función Ejecutiva , Femenino , Humanos , Masculino , Estudios Longitudinales , Solución de Problemas , Estudios Prospectivos , Adulto
10.
Transl Psychiatry ; 12(1): 317, 2022 08 06.
Artículo en Inglés | MEDLINE | ID: mdl-35933470

RESUMEN

The association between extent of chronic cannabis use (CCU-extent) and cognitive impairment among adolescents has been the subject of controversial debate. Linking DNA methylation to CCU-extent could help to understand cannabis associated changes in cognitive performance. We analyzed cognitive task performances, CpG methylation in peripheral whole-blood samples and self-reported past-year CCU-extent of n = 18 adolescents (n = 9 psychiatric outpatients with chronic cannabis use (CCU), n = 9 without) who were matched for age, gender and psychiatric disorders. Patients with CCU were at least 24 h abstinent when cognitive tasks were performed. A Principal Component Analysis (PCA) was carried out to identify group differences in whole genome DNA methylation. Mediation analyses were performed between CCU-extent associated CpG sites and CCU-extent associated variables of cognitive tasks. PCA results indicated large differences in whole genome DNA methylation levels between the groups that did not reach statistical significance. Six CpG sites revealed reduced methylation associated with CCU-extent. Furthermore, CCU-extent was associated with lower scores in verbal learning. All six CpG sites mediated the effects between CCU-extent and verbal learning free recall. Our results indicate that CCU is associated with certain patterns in the methylome. Furthermore, CCU-extent associated impairments in memory function are mediated via differential methylation of the six CCU-associated CpG sits. Six identified CpG are located in genes previously described in the context of neurodegeneration, hippocampus-dependent learning and neurogenesis. However, these results have to be carefully interpreted due to a small sample size. Replication studies are warranted.


Asunto(s)
Cannabis , Alucinógenos , Adolescente , Islas de CpG , ADN , Metilación de ADN , Genoma Humano , Humanos , Aprendizaje Verbal
11.
Soft Matter ; 18(33): 6222-6228, 2022 Aug 24.
Artículo en Inglés | MEDLINE | ID: mdl-35894155

RESUMEN

We study the self-assembly of branching-chain networks and crystals in a binary colloidal system with tunable interactions. The particle positions are extracted from microscopy images and order parameters are extracted by image processing and statistical analysis. With these, we construct phase diagrams with respect to particle density, ratio and interaction. In order to draw a more complete picture, we complement the experiments with computer simulations. We establish a region in the phase diagram, where bead ratios and interactions are symmetric, promoting percolated structures.

12.
Eur Psychiatry ; 65(1): e39, 2022 06 16.
Artículo en Inglés | MEDLINE | ID: mdl-35707860

RESUMEN

BACKGROUND: Individuals with anorexia nervosa (AN) are often thought to show heightened self-control and increased ability to inhibit desires. In addition to inhibitory self-control, antecedent-focused strategies (e.g., cognitive reconstrual-the re-evaluation of tempting situations) might contribute to disorder maintenance and enable disorder-typical, maladaptive behaviors. METHODS: Over a period of 14 days, 40 acutely underweight young female patients with anorexia nervosa (AN) and 40 healthy control (HC) participants reported their affect and behavior in self-control situations via ecological momentary assessment during inpatient treatment (AN) and everyday life (HC). Data were analyzed via hierarchical analyses (linear and logistic modeling). RESULTS: Conflict strength had a significantly lower impact on self-control success in AN compared to HC. While AN and HC did not generally differ in the number or strength of self-control conflicts or in the percentage of self-control success, AN reported self-controlled behavior to be less dependent on conflict strength. CONCLUSIONS: While patients with AN were not generally more successful at self-control, they appeared to resolve self-control conflicts more effectively. These findings suggest that the magnitude of self-control conflicts has comparatively little impact on individuals with AN, possibly due to the use of antecedent-focused strategies. If confirmed, cognitive-behavioral therapy might focus on and help patients to exploit these alternative self-control strategies in the battle against their illness.


Asunto(s)
Anorexia Nerviosa , Terapia Cognitivo-Conductual , Autocontrol , Anorexia Nerviosa/psicología , Anorexia Nerviosa/terapia , Evaluación Ecológica Momentánea , Femenino , Humanos
13.
J Psychopharmacol ; 36(3): 387-408, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-35253518

RESUMEN

BACKGROUND: Many benefits and some harms associated with psychedelic use could be attributable to these drugs' acceptance/avoidance-promoting effects and corresponding changes in psychological flexibility. Underlying psychological mechanisms are insufficiently understood. AIM: The purpose of this study was the validation of a psychological model of acceptance/avoidance-promoting psychedelic experiences, which included the development of a theory-based self-report instrument: the Acceptance/Avoidance-Promoting Experiences Questionnaire (APEQ). Its two main scales, acceptance-related experience (ACE) and avoidance-related experience (AVE), represent the theorized model's core constructs. We aimed to test the model's central assumptions of complementarity (ACE and AVE may occur alternatingly but not simultaneously, and are therefore empirically independent), intertwinedness (subaspects within ACE and AVE are mutually contingent and therefore highly inter-correlated), context-dependence (ACE and AVE depend on context factors) and interaction (longer-term outcomes depend on the interplay between ACE and AVE). METHOD: A bilingual retrospective online survey including 997 English- and 836 German-speaking participants. Each participant reported on one psychedelic experience occasioned by lysergic acid diethylamide (LSD), psilocybin, mescaline, or ayahuasca. RESULTS: Whereas ACE and AVE were found to be relatively independent aspects of participants' reported psychedelic experiences (complementarity), their subaspects were mostly distinguishable but strongly correlated among each other (intertwinedness). Therapeutic, escapist, and hedonic use motives were differentially associated with ACE and AVE (context-dependence), which were in turn associated with retrospective changes in psychological flexibility following participants' reported experiences. The positive association between ACE and increased psychological flexibility was significantly moderated by AVE (interaction). CONCLUSION: These results provide an initial validation of the APEQ and its underlying theoretical model, suggesting the two can help clarify the psychological mechanisms of psychedelic-induced benefits and harms. Both should be further investigated in prospective-longitudinal and clinical studies.


Asunto(s)
Alucinógenos , Alucinógenos/efectos adversos , Humanos , Dietilamida del Ácido Lisérgico/farmacología , Dietilamida del Ácido Lisérgico/uso terapéutico , Estudios Prospectivos , Psilocibina/farmacología , Psilocibina/uso terapéutico , Estudios Retrospectivos , Encuestas y Cuestionarios
14.
Phys Rev Lett ; 127(13): 136102, 2021 Sep 24.
Artículo en Inglés | MEDLINE | ID: mdl-34623839

RESUMEN

We report real space location of hydrogen in single crystalline Fe/V superstructures. Anisotropic strain is quantified versus hydrogen concentration by using the yield of backscattered primary 2 MeV ^{4}He ions for incidence in different crystallographic directions. From a comparison of ion channeling in combination with ^{1}H(^{15}N,αγ)^{12}C nuclear reaction analysis and Monte Carlo simulations we show that hydrogen is located in octahedral z sites and quantify its vibrational amplitude of 0.2 Å.

15.
Sci Rep ; 11(1): 17786, 2021 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-34493764

RESUMEN

We have performed grazing incidence neutron small angle scattering using a fan shaped incident beam focused along one dimension. This allows significantly reduced counting times for measurements of lateral correlations parallel to an interface or in a thin film where limited depth resolution is required. We resolve the structure factor of iron inclusions in aluminium oxide and show that the ordering of silica particles deposited on a silicon substrate depends on their size. We report hexagonal packing for 50 nm but not for 200 nm silica spheres deposited by a modified Langmuir-Schaefer method on a silicon substrate. For the 200 nm particles we extract the particles shape from the form factor. Moreover, we report dense packing of the particles spread on a free water surface. We name this method π-GISANS to highlight that it differs from GISANS as it gives lateral information while averaging the in-depth structure.

16.
Cogn Affect Behav Neurosci ; 21(5): 936-947, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34075542

RESUMEN

Despite its relevance for health and education, the neurocognitive mechanism of real-life self-control is largely unknown. While recent research revealed a prominent role of the ventromedial prefrontal cortex in the computation of an integrative value signal, the contribution and relevance of other brain regions for real-life self-control remains unclear. To investigate neural correlates of decisions in line with long-term consequences and to assess the potential of brain decoding methods for the individual prediction of real-life self-control, we combined functional magnetic resonance imaging during preference decision making with ecological momentary assessment of daily self-control in a large community sample (N = 266). Decisions in line with long-term consequences were associated with increased activity in bilateral angular gyrus and precuneus, regions involved in different forms of perspective taking, such as imagining one's own future and the perspective of others. Applying multivariate pattern analysis to the same clusters revealed that individual patterns of activity predicted the probability of real-life self-control. Brain activations are discussed in relation to episodic future thinking and mentalizing as potential mechanisms mediating real-life self-control.


Asunto(s)
Mapeo Encefálico , Autocontrol , Encéfalo/diagnóstico por imagen , Toma de Decisiones , Humanos , Imagen por Resonancia Magnética
17.
Langmuir ; 37(14): 4064-4071, 2021 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-33797254

RESUMEN

We study the assembly of magnetite nanoparticles in water-based ferrofluids in wetting layers close to silicon substrates with different functionalization without and with an out-of-plane magnetic field. For particles of nominal sizes 5, 15, and 25 nm, we extract density profiles from neutron reflectivity measurements. We show that self-assembly is only promoted by a magnetic field if a seed layer is formed at the silicon substrate. Such a layer can be formed by chemisorption of activated N-hydroxysuccinimide ester-coated nanoparticles at a (3-aminopropyl)triethoxysilane functionalized surface. Less dense packing is reported for physisorption of the same particles at a piranha-treated (strongly hydrophilic) silicon wafer, and no wetting layer is found for a self-assembled monolayer of octadecyltrichlorosilane (strongly hydrophobic) at the interface. We show that once the seed layer is formed and under an out-of-plane magnetic field further wetting layers assemble. These layers become denser with time, larger magnetic fields, higher particle concentrations, and larger moment of the nanoparticles.

18.
J Pers ; 89(6): 1113-1125, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-33866562

RESUMEN

OBJECTIVE: Need for Cognition (NFC) refers to a personality trait describing the relatively stable intrinsic motivation of individuals to invest cognitive effort in cognitive endeavors. Higher NFC is associated with a more elaborated, central information processing style and increased recruitment of resources in cognitively demanding situations. To further clarify the association between cognitive resources and NFC, we examined in two studies how NFC relates to executive functions as basic cognitive abilities. METHOD: In Study 1, 189 healthy young adults completed an NFC scale and a battery of six commonly used inhibitory control tasks (Stroop, antisaccade, stop-signal, flanker, shape-matching, word-naming). In Study 2, 102 healthy young adults completed the NFC scale and two tasks for each of the three executive functions inhibitory control (go-nogo, stop-signal), shifting (number-letter, color-shape), and working memory updating (two-back, letter-memory). RESULTS: Using a Bayesian approach to correlation analysis, we found no conclusive evidence that NFC was related to any executive function measure. Instead, we obtained even moderate evidence for the null hypothesis. CONCLUSIONS: Both studies add to more recent findings that shape the understanding of NFC as a trait that is less characterized by increased cognitive control abilities but rather by increased willingness to invest effort and exert self-control via motivational processes.


Asunto(s)
Función Ejecutiva , Autocontrol , Teorema de Bayes , Cognición , Humanos , Motivación , Adulto Joven
19.
Rev Sci Instrum ; 92(2): 023306, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33648099

RESUMEN

Graphite intercalation compounds (GICs) are a group of layered materials that are suitable as monochromators for cold neutrons. KC24 is a particularly interesting compound in this regard as it features a large c-axis lattice spacing of 8.74 Å, high reflectivity, and the possibility to produce large crystals with mosaicity that matches the beam divergence of cold neutron guides. GICs can be synthesized with different levels of intercalation, known as the stage of the compounds. Each stage displays a specific d-spacing. Impure GIC-monochromators containing multiple stages produce mixing of neutron wavelengths, which complicates data analysis on neutron reflectometers. We discuss the implications of GIC crystal purity and stage contamination for neutron reflectometry and show how GIC crystals can be characterized by time-of-flight neutron diffraction providing an efficient and quantifiable measure of the reflected wavelength spectrum. This allows taking into account multiple wavelength contaminations and ascertains the robustness of reflectometry measurements.

20.
J Pers ; 89(3): 402-421, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-32858777

RESUMEN

OBJECTIVE: To test the hypothesis that chronic stress impairs the use of cognitive control for self-control, we examined how chronic stress affects the relation between individual differences in general executive functioning (GEF) and self-control in real-life situations. METHOD: About 338 young adults with varying degrees of chronic stress underwent experience sampling of real-life self-control for 7 days and completed a battery of nine executive function tasks from which a latent variable representing individual differences in GEF was derived. RESULTS: Structural equation models showed that higher levels of chronic stress were associated with stronger desires and a less negative relationship between GEF and desire strength. Chronic stress and GEF did not predict desire enactment in situations where effortful resistance was attempted. CONCLUSIONS: These findings suggest that chronic stress may impair self-control by reducing the use of cognitive control for "early" desire regulation strategies while leaving "late" resistance strategies unaffected. That relationships between executive functioning and real-life self-control can be moderated by third factors such as chronic stress may to some extent explain the common finding of weak or missing associations between laboratory measures of executive functioning and real-life self-control.


Asunto(s)
Función Ejecutiva , Autocontrol , Evaluación Ecológica Momentánea , Humanos , Individualidad , Adulto Joven
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