Publications by authors named "Joachim Gross"

173 Publications

Accurate first-order perturbation theory for fluids: uf-theory.

J Chem Phys 2021 Jan;154(4):041102

Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, D-70569 Stuttgart, Germany.

We propose a new first-order perturbation theory that provides a near-quantitative description of the thermodynamics of simple fluids. The theory is based on the ansatz that the Helmholtz free energy is bounded below by a first-order Mayer-f expansion. Together with the rigorous upper bound provided by a first-order u-expansion, this brackets the actual free energy between an upper and (effective) lower bound that can both be calculated based on first-order perturbation theory. This is of great practical use. Here, the two bounds are combined into an interpolation scheme for the free energy. The scheme exploits the fact that a first-order Mayer-f perturbation theory is exact in the low-density limit, whereas the accuracy of a first-order u-expansion grows when density increases. This allows an interpolation between the lower "f"-bound at low densities and the upper "u" bound at higher liquid-like densities. The resulting theory is particularly well behaved. Using a density-dependent interpolating function of only two adjustable parameters, we obtain a very accurate representation of the full fluid-phase behavior of a Lennard-Jones fluid. The interpolating function is transferable to other intermolecular potential types, which is here shown for the Mie m-6 family of fluids. The extension to mixtures is simple and accurate without requiring any dependence of the interpolating function on the composition of the mixture.
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http://dx.doi.org/10.1063/5.0031545DOI Listing
January 2021

Effect of Capsaicinoids on Neurophysiological, Biochemical, and Mechanical Parameters of Swallowing Function.

Neurotherapeutics 2021 Jan 15. Epub 2021 Jan 15.

Department of Neurology, University Hospital Muenster, Albert-Schweitzer-Campus 1 A, 48149, Muenster, Germany.

Oropharyngeal dysphagia is prevalent in age-related neurological disorders presenting with impaired efficacy and safety of swallowing due to a loss of muscle force and sensory deficits. Stimulating the oropharynx with capsaicin that mediates Substance P release is an emerging pharmacological treatment option which needs further scientific evidence. Our aim was to comprehensively evaluate the effect of capsaicin on biochemical, neurophysiological, and biomechanical parameters of swallowing function. In a randomized study on healthy individuals, the impact of orally administered capsaicinoids at different dosages and application durations in comparison to non-carbonated water was evaluated. Time course and magnitude of salivary Substance P increase were monitored. Magnetoencephalography was used to detect cortical swallowing network alterations. Modifications in swallowing biomechanics were measured applying high-resolution pharyngeal manometry. Capsaicinoids at 10 μmol/L improved swallowing efficacy as seen by a significant increase of pharyngeal contractile integral and upper esophageal sphincter activation and relaxation times in manometry. Significant improvement of precision in a challenging swallow task accompanied by a reduction in swallowing-related submental electromyographic power was observed with capsaicinoids preconditioning at 10 μmol/L over 5 min, but not with continuous stimulation. The cortical activation pattern remained unchanged after any intervention. A significant increase of salivary Substance P was not detected with 10 μmol/L but with 50 μmol/L and lasted for 15 min after application. Capsaicinoids mediate dose-dependent Substance P release and positively alter swallowing biomechanics in healthy subjects. The results provide supportive evidence for the value of natural capsaicinoids to improve swallowing function.
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http://dx.doi.org/10.1007/s13311-020-00996-2DOI Listing
January 2021

Effect of Capsaicinoids on Neurophysiological, Biochemical, and Mechanical Parameters of Swallowing Function.

Neurotherapeutics 2021 Jan 15. Epub 2021 Jan 15.

Department of Neurology, University Hospital Muenster, Albert-Schweitzer-Campus 1 A, 48149, Muenster, Germany.

Oropharyngeal dysphagia is prevalent in age-related neurological disorders presenting with impaired efficacy and safety of swallowing due to a loss of muscle force and sensory deficits. Stimulating the oropharynx with capsaicin that mediates Substance P release is an emerging pharmacological treatment option which needs further scientific evidence. Our aim was to comprehensively evaluate the effect of capsaicin on biochemical, neurophysiological, and biomechanical parameters of swallowing function. In a randomized study on healthy individuals, the impact of orally administered capsaicinoids at different dosages and application durations in comparison to non-carbonated water was evaluated. Time course and magnitude of salivary Substance P increase were monitored. Magnetoencephalography was used to detect cortical swallowing network alterations. Modifications in swallowing biomechanics were measured applying high-resolution pharyngeal manometry. Capsaicinoids at 10 μmol/L improved swallowing efficacy as seen by a significant increase of pharyngeal contractile integral and upper esophageal sphincter activation and relaxation times in manometry. Significant improvement of precision in a challenging swallow task accompanied by a reduction in swallowing-related submental electromyographic power was observed with capsaicinoids preconditioning at 10 μmol/L over 5 min, but not with continuous stimulation. The cortical activation pattern remained unchanged after any intervention. A significant increase of salivary Substance P was not detected with 10 μmol/L but with 50 μmol/L and lasted for 15 min after application. Capsaicinoids mediate dose-dependent Substance P release and positively alter swallowing biomechanics in healthy subjects. The results provide supportive evidence for the value of natural capsaicinoids to improve swallowing function.
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http://dx.doi.org/10.1007/s13311-020-00996-2DOI Listing
January 2021

Altered Autonomic Function in Individuals at Clinical High Risk for Psychosis.

Front Psychiatry 2020 6;11:580503. Epub 2020 Nov 6.

Institute for Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.

Alterations in autonomic functioning in individuals diagnosed with schizophrenia are well-documented. Yet, it is currently unclear whether these dysfunctions extend into the clinical high-risk state. Thus, we investigated resting heart rate (RHR) and heart rate variability (HRV) indices in individuals at clinical high-risk for psychosis (CHR-P). We recruited 117 CHR-P participants, 38 participants with affective disorders and substance abuse (CHR-N) as well as a group of 49 healthy controls. CHR-P status was assessed with the Comprehensive Assessment of At-Risk Mental States (CAARMS) and the Schizophrenia Proneness Instrument, Adult Version (SPI-A). We obtained 5 min, eyes-open resting-state MEG data, which was used for the extraction of cardiac field-related inter-beat-interval data and from which heart-rate and heart-rate variability measures were computed. Compared to both CHR-N and healthy controls, CHR-P participants were characterized by an increased RHR, which was not explained by differences in psychopathological comorbidity and medication status. Increased RHR correlated with the presence of subthreshold psychotic symptoms and associated distress. No differences between groups were found for heart-rate variability measures, however. Furthermore, there was an association between motor-performance and psychophysiological measures. The current study provides evidence of alterations in autonomic functioning as disclosed by increased RHR in CHR-P participants. Future studies are needed to further evaluate this characteristic feature of CHR-P individuals and its potential predictive value for psychosis development.
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http://dx.doi.org/10.3389/fpsyt.2020.580503DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7677235PMC
November 2020

Targeting the sensory feedback within the swallowing network-Reversing artificially induced pharyngolaryngeal hypesthesia by central and peripheral stimulation strategies.

Hum Brain Mapp 2021 Feb 17;42(2):427-438. Epub 2020 Oct 17.

Department of Neurology with Institute of Translational Neurology, University Hospital Muenster, Muenster, Germany.

Pharyngolaryngeal hypesthesia is a major reason for dysphagia in various neurological diseases. Emerging neuromodulation devices have shown potential to foster dysphagia rehabilitation, but the optimal treatment strategy is unknown. Because functional imaging studies are difficult to conduct in severely ill patients, we induced a virtual sensory lesion in healthy volunteers and evaluated the effects of central and peripheral neurostimulation techniques. In a sham-controlled intervention study with crossover design on 10 participants, we tested the potential of (peripheral) pharyngeal electrical stimulation (PES) and (central) transcranial direct current stimulation (tDCS) to revert the effects of lidocaine-induced pharyngolaryngeal hypesthesia on central sensorimotor processing. Changes were observed during pharyngeal air-pulse stimulation and voluntary swallowing applying magnetoencephalography before and after the interventions. PES induced a significant (p < .05) increase of activation during swallowing in the bihemispheric sensorimotor network in alpha and low gamma frequency ranges, peaking in the right premotor and left primary sensory area, respectively. With pneumatic stimulation, significant activation increase was found after PES in high gamma peaking in the left premotor area. Significant changes of brain activation after tDCS could neither be detected for pneumatic stimulation nor for swallowing. Due to the peripheral cause of dysphagia in this model, PES was able to revert the detrimental effects of reduced sensory input on central processing, whereas tDCS was not. Results may have implications for therapeutic decisions in the clinical context.
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http://dx.doi.org/10.1002/hbm.25233DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7776007PMC
February 2021

Inter-Subject Variability of Skull Conductivity and Thickness in Calibrated Realistic Head Models.

Neuroimage 2020 12 9;223:117353. Epub 2020 Sep 9.

Institute for Biomagnetism and Biosignalanalysis, University of Münster, Münster, Germany; Centre for Cognitive Neuroimaging (CCNi), University of Glasgow, Glasgow, UK.

Skull conductivity has a substantial influence on EEG and combined EEG and MEG source analysis as well as on optimized transcranial electric stimulation. To overcome the use of standard literature values, we propose a non-invasive two-level calibration procedure to estimate skull conductivity individually in a group study with twenty healthy adults. Our procedure requires only an additional run of combined somatosensory evoked potential and field data, which can be easily integrated in EEG/MEG experiments. The calibration procedure uses the P20/N20 topographies and subject-specific realistic head models from MRI. We investigate the inter-subject variability of skull conductivity and relate it to skull thickness, age and gender of the subjects, to the individual scalp P20/N20 surface distance between the P20 potential peak and the N20 potential trough as well as to the individual source depth of the P20/N20 source. We found a considerable inter-subject variability for (calibrated) skull conductivity (8.44 ± 4.84 mS/m) and skull thickness (5.97 ± 1.19 mm) with a statistically significant correlation between them (rho = 0.52). Age showed a statistically significant negative correlation with skull conductivity (rho = -0.5). Furthermore, P20/N20 surface distance and source depth showed large inter-subject variability of 12.08 ± 3.21 cm and 15.45 ± 4.54 mm, respectively, but there was no significant correlation between them. We also found no significant differences among gender subgroups for the investigated measures. It is thus important to take the inter-subject variability of skull conductivity and thickness into account by means of using subject-specific calibrated realistic head modeling.
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http://dx.doi.org/10.1016/j.neuroimage.2020.117353DOI Listing
December 2020

Investigating the effects of pre-stimulus cortical oscillatory activity on behavior.

Neuroimage 2020 12 6;223:117351. Epub 2020 Sep 6.

Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Kapittelweg 29, 6525 EN Nijmegen, the Netherlands; Department of Psychology, Centre for Cognitive Neuroimaging, University of Glasgow, 62 Hillhead Street, G12 8QB Glasgow, UK.

Rhythmic brain activity may reflect a functional mechanism that facilitates cortical processing and dynamic interareal interactions and thereby give rise to complex behavior. Using magnetoencephalography (MEG), we investigated rhythmic brain activity in a brain-wide network and their relation to behavior, while human subjects executed a variant of the Simon task, a simple stimulus-response task with well-studied behavioral effects. We hypothesized that the faster reaction times (RT) on stimulus-response congruent versus incongruent trials are associated with oscillatory power changes, reflecting a change in local cortical activation. Additionally, we hypothesized that the faster reaction times for trials following instances with the same stimulus-response contingency (the so-called Gratton effect) is related to contingency-induced changes in the state of the network, as measured by differences in local spectral power and interareal phase coherence. This would be achieved by temporarily upregulating the connectivity strength between behaviorally relevant network nodes. We identified regions-of-interest that differed in local synchrony during the response phase of the Simon task. Within this network, spectral power in none of the nodes in either of the studied frequencies was significantly different in the pre-cue window of the subsequent trial. Nor was there a significant difference in coherence between the task-relevant nodes that could explain the superior behavioral performance after compatible consecutive trials.
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http://dx.doi.org/10.1016/j.neuroimage.2020.117351DOI Listing
December 2020

Cortical tracking of speech in noise accounts for reading strategies in children.

PLoS Biol 2020 08 26;18(8):e3000840. Epub 2020 Aug 26.

Laboratoire de Cartographie fonctionnelle du Cerveau, UNI-ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium.

Humans' propensity to acquire literacy relates to several factors, including the ability to understand speech in noise (SiN). Still, the nature of the relation between reading and SiN perception abilities remains poorly understood. Here, we dissect the interplay between (1) reading abilities, (2) classical behavioral predictors of reading (phonological awareness, phonological memory, and rapid automatized naming), and (3) electrophysiological markers of SiN perception in 99 elementary school children (26 with dyslexia). We demonstrate that, in typical readers, cortical representation of the phrasal content of SiN relates to the degree of development of the lexical (but not sublexical) reading strategy. In contrast, classical behavioral predictors of reading abilities and the ability to benefit from visual speech to represent the syllabic content of SiN account for global reading performance (i.e., speed and accuracy of lexical and sublexical reading). In individuals with dyslexia, we found preserved integration of visual speech information to optimize processing of syntactic information but not to sustain acoustic/phonemic processing. Finally, within children with dyslexia, measures of cortical representation of the phrasal content of SiN were negatively related to reading speed and positively related to the compromise between reading precision and reading speed, potentially owing to compensatory attentional mechanisms. These results clarify the nature of the relation between SiN perception and reading abilities in typical child readers and children with dyslexia and identify novel electrophysiological markers of emergent literacy.
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http://dx.doi.org/10.1371/journal.pbio.3000840DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7478533PMC
August 2020

Shared and modality-specific brain regions that mediate auditory and visual word comprehension.

Elife 2020 08 24;9. Epub 2020 Aug 24.

Department for Cognitive Neuroscience, Faculty of Biology, Bielefeld University, Bielefeld, Germany.

Visual speech carried by lip movements is an integral part of communication. Yet, it remains unclear in how far visual and acoustic speech comprehension are mediated by the same brain regions. Using multivariate classification of full-brain MEG data, we first probed where the brain represents acoustically and visually conveyed word identities. We then tested where these sensory-driven representations are predictive of participants' trial-wise comprehension. The comprehension-relevant representations of auditory and visual speech converged only in anterior angular and inferior frontal regions and were spatially dissociated from those representations that best reflected the sensory-driven word identity. These results provide a neural explanation for the behavioural dissociation of acoustic and visual speech comprehension and suggest that cerebral representations encoding word identities may be more modality-specific than often upheld.
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http://dx.doi.org/10.7554/eLife.56972DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7470824PMC
August 2020

Depth and phase of respiration modulate cortico-muscular communication.

Neuroimage 2020 11 18;222:117272. Epub 2020 Aug 18.

Institute for Biomagnetism and Biosignal Analysis, University of Münster, Münster, Germany; Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany; Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.

Recent studies in animals have convincingly demonstrated that respiration cyclically modulates oscillatory neural activity across diverse brain areas. To what extent this generalises to humans in a way that is relevant for behaviour is yet unclear. We used magnetoencephalography (MEG) to assess the potential influence of respiration depth and respiration phase on the human motor system. We obtained simultaneous recordings of brain activity, muscle activity, and respiration while participants performed a steady contraction task. We used corticomuscular coherence as a measure of efficient long-range cortico-peripheral communication. We found coherence within the beta range over sensorimotor cortex to be reduced during voluntary deep compared to involuntary normal breathing. Moreover, beta coherence was found to be cyclically modulated by respiration phase in both conditions. Overall, these results demonstrate how respiratory rhythms influence the synchrony of brain oscillations, conceivably regulating computational efficiency through neural excitability. Intriguing questions remain with regard to the shape of these modulatory processes and how they influence perception, cognition, and behaviour.
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http://dx.doi.org/10.1016/j.neuroimage.2020.117272DOI Listing
November 2020

The frequency gradient of human resting-state brain oscillations follows cortical hierarchies.

Elife 2020 08 21;9. Epub 2020 Aug 21.

Institute for Biomagnetism and Biosignalanalysis (IBB), University of Muenster, Muenster, Germany.

The human cortex is characterized by local morphological features such as cortical thickness, myelin content, and gene expression that change along the posterior-anterior axis. We investigated if some of these structural gradients are associated with a similar gradient in a prominent feature of brain activity - namely the frequency of oscillations. In resting-state MEG recordings from healthy participants (N = 187) using mixed effect models, we found that the dominant peak frequency in a brain area decreases significantly along the posterior-anterior axis following the global hierarchy from early sensory to higher order areas. This spatial gradient of peak frequency was significantly anticorrelated with that of cortical thickness, representing a proxy of the cortical hierarchical level. This result indicates that the dominant frequency changes systematically and globally along the spatial and hierarchical gradients and establishes a new structure-function relationship pertaining to brain oscillations as a core organization that may underlie hierarchical specialization in the brain.
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http://dx.doi.org/10.7554/eLife.53715DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7476753PMC
August 2020

Perturbation approaches for describing dipolar fluids and electrolyte solutions.

J Chem Phys 2020 Jul;153(4):044102

Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart, Germany.

This work proposes perturbation approaches for describing dipolar fluids as well as model and aqueous electrolyte solutions. The electrostatic pair potentials are split into short- and long-ranged contributions, whereas a third order perturbation expansion is applied for the short-ranged potentials. This circumvents the problem of divergent correlation integrals. The dipolar perturbation terms are represented through a [2,1]-Padé approximation to resum the poorly convergent series. For the remaining charge-charge and charge-dipole contributions, we present a new approximant, which provides a (quasi)linear dependence of the Helmholtz energy. The underlying correlation integrals are adjusted to results from molecular simulations. The long-ranged contribution to the electrostatic interactions is treated through an analytic expression developed by Rodgers and Weeks [J. Chem. Phys. 131, 244108 (2010)]. Theoretical predictions of our perturbation theory are compared to results from a widely used integral equation theory, namely, the mean spherical approximation, and we find that our perturbation theory provides much more accurate results. Furthermore, the theory shows some quantities in rather good agreement with reference data, namely, Helmholtz energies, internal energies, and densities at higher densities of solutions. Limitations of the approach, however, are observed for several other partial molar quantities, such as the mean activity coefficient.
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http://dx.doi.org/10.1063/5.0011384DOI Listing
July 2020

Investigating cortico-subcortical circuits during auditory sensory attenuation: A combined magnetoencephalographic and dynamic causal modeling study.

Hum Brain Mapp 2020 Oct 14;41(15):4419-4430. Epub 2020 Jul 14.

Institute for Neuroscience and Psychology, University of Glasgow, Glasgow, UK.

Sensory attenuation refers to the decreased intensity of a sensory percept when a sensation is self-generated compared with when it is externally triggered. However, the underlying brain regions and network interactions that give rise to this phenomenon remain to be determined. To address this issue, we recorded magnetoencephalographic (MEG) data from 35 healthy controls during an auditory task in which pure tones were either elicited through a button press or passively presented. We analyzed the auditory M100 at sensor- and source-level and identified movement-related magnetic fields (MRMFs). Regression analyses were used to further identify brain regions that contributed significantly to sensory attenuation, followed by a dynamic causal modeling (DCM) approach to explore network interactions between generators. Attenuation of the M100 was pronounced in right Heschl's gyrus (HES), superior temporal cortex (ST), thalamus, rolandic operculum (ROL), precuneus and inferior parietal cortex (IPL). Regression analyses showed that right postcentral gyrus (PoCG) and left precentral gyrus (PreCG) predicted M100 sensory attenuation. In addition, DCM results indicated that auditory sensory attenuation involved bi-directional information flow between thalamus, IPL, and auditory cortex. In summary, our data show that sensory attenuation is mediated by bottom-up and top-down information flow in a thalamocortical network, providing support for the role of predictive processing in sensory-motor system.
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http://dx.doi.org/10.1002/hbm.25134DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7502827PMC
October 2020

Brain activity reflects the predictability of word sequences in listened continuous speech.

Neuroimage 2020 10 29;219:116936. Epub 2020 May 29.

Department of Neuroscience and Biomedical Engineering, P.O. Box 12200, FI-00076, Aalto University, Finland; Department of Art, P.O. Box 31000, FI-00076, Aalto University, Finland.

Natural speech builds on contextual relations that can prompt predictions of upcoming utterances. To study the neural underpinnings of such predictive processing we asked 10 healthy adults to listen to a 1-h-long audiobook while their magnetoencephalographic (MEG) brain activity was recorded. We correlated the MEG signals with acoustic speech envelope, as well as with estimates of Bayesian word probability with and without the contextual word sequence (N-gram and Unigram, respectively), with a focus on time-lags. The MEG signals of auditory and sensorimotor cortices were strongly coupled to the speech envelope at the rates of syllables (4-8 ​Hz) and of prosody and intonation (0.5-2 ​Hz). The probability structure of word sequences, independently of the acoustical features, affected the ≤ 2-Hz signals extensively in auditory and rolandic regions, in precuneus, occipital cortices, and lateral and medial frontal regions. Fine-grained temporal progression patterns occurred across brain regions 100-1000 ​ms after word onsets. Although the acoustic effects were observed in both hemispheres, the contextual influences were statistically significantly lateralized to the left hemisphere. These results serve as a brain signature of the predictability of word sequences in listened continuous speech, confirming and extending previous results to demonstrate that deeply-learned knowledge and recent contextual information are employed dynamically and in a left-hemisphere-dominant manner in predicting the forthcoming words in natural speech.
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http://dx.doi.org/10.1016/j.neuroimage.2020.116936DOI Listing
October 2020

The perception of caricatured emotion in voice.

Cognition 2020 07 12;200:104249. Epub 2020 May 12.

Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK; Institut de Neurosciences de la Timone, CNRS UMR 7289, Aix-Marseille Université, Marseille, France.

Affective vocalisations such as screams and laughs can convey strong emotional content without verbal information. Previous research using morphed vocalisations (e.g. 25% fear/75% anger) has revealed categorical perception of emotion in voices, showing sudden shifts at emotion category boundaries. However, it is currently unknown how further modulation of vocalisations beyond the veridical emotion (e.g. 125% fear) affects perception. Caricatured facial expressions produce emotions that are perceived as more intense and distinctive, with faster recognition relative to the original and anti-caricatured (e.g. 75% fear) emotions, but a similar effect using vocal caricatures has not been previously examined. Furthermore, caricatures can play a key role in assessing how distinctiveness is identified, in particular by evaluating accounts of emotion perception with reference to prototypes (distance from the central stimulus) and exemplars (density of the stimulus space). Stimuli consisted of four emotions (anger, disgust, fear, and pleasure) morphed at 25% intervals between a neutral expression and each emotion from 25% to 125%, and between each pair of emotions. Emotion perception was assessed using emotion intensity ratings, valence and arousal ratings, speeded categorisation and paired similarity ratings. We report two key findings: 1) across tasks, there was a strongly linear effect of caricaturing, with caricatured emotions (125%) perceived as higher in emotion intensity and arousal, and recognised faster compared to the original emotion (100%) and anti-caricatures (25%-75%); 2) our results reveal evidence for a unique contribution of a prototype-based account in emotion recognition. We show for the first time that vocal caricature effects are comparable to those found previously with facial caricatures. The set of caricatured vocalisations provided open a promising line of research for investigating vocal affect perception and emotion processing deficits in clinical populations.
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http://dx.doi.org/10.1016/j.cognition.2020.104249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7315128PMC
July 2020

Association of Magnetoencephalographically Measured High-Frequency Oscillations in Visual Cortex With Circuit Dysfunctions in Local and Large-scale Networks During Emerging Psychosis.

JAMA Psychiatry 2020 08;77(8):852-862

Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, Scotland.

Importance: Psychotic disorders are characterized by impairments in neural oscillations, but the nature of the deficit, the trajectory across illness stages, and functional relevance remain unclear.

Objectives: To examine whether changes in spectral power, phase locking, and functional connectivity in visual cortex are present during emerging psychosis and whether these abnormalities are associated with clinical outcomes.

Design, Setting, And Participants: In this cross-sectional study, participants meeting clinical high-risk criteria for psychosis, participants with first-episode psychosis, participants with affective disorders and substance abuse, and a group of control participants were recruited. Participants underwent measurements with magnetoencephalography and magnetic resonance imaging. Data analysis was carried out between 2018 and 2019.

Main Outcomes And Measures: Magnetoencephalographical activity was examined in the 1- to 90-Hz frequency range in combination with source reconstruction during a visual grating task. Event-related fields, power modulation, intertrial phase consistency, and connectivity measures in visual and frontal cortices were associated with neuropsychological scores, psychosocial functioning, and clinical symptoms as well as persistence of subthreshold psychotic symptoms at 12 months.

Results: The study participants included those meeting clinical high-risk criteria for psychosis (n = 119; mean [SD] age, 22 [4.4] years; 32 men), 26 patients with first-episode psychosis (mean [SD] age, 24 [4.2] years; 16 men), 38 participants with affective disorders and substance abuse (mean [SD] age, 23 [4.7] years; 11 men), and 49 control participants (mean age [SD], 23 [3.6] years; 16 men). Clinical high-risk participants and patients with first-episode psychosis were characterized by reduced phase consistency of β/γ-band oscillations in visual cortex (d = 0.63/d = 0.93). Moreover, the first-episode psychosis group was also characterized by reduced occipital γ-band power (d = 1.14) and altered visual cortex connectivity (d = 0.74-0.84). Impaired fronto-occipital connectivity was present in both clinical high-risk participants (d = 0.54) and patients with first-episode psychosis (d = 0.84). Importantly, reductions in intertrial phase coherence predicted persistence of subthreshold psychosis in clinical high-risk participants (receiver operating characteristic area under curve = 0.728; 95% CI, 0.612-0.841; P = .001).

Conclusions And Relevance: High-frequency oscillations are impaired in the visual cortex during emerging psychosis and may be linked to behavioral and clinical impairments. Impaired phase consistency of γ-band oscillations was also associated with the persistence of subthreshold psychosis, suggesting that magnetoencephalographical measured neural oscillations could constitute a biomarker for clinical staging of emerging psychosis.
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http://dx.doi.org/10.1001/jamapsychiatry.2020.0284DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7097849PMC
August 2020

CD163 expression defines specific, IRF8-dependent, immune-modulatory macrophages in the bone marrow.

J Allergy Clin Immunol 2020 Nov 19;146(5):1137-1151. Epub 2020 Mar 19.

Institute of Immunology, University of Muenster, Muenster, Germany. Electronic address:

Background: Scavenger receptor CD163 is exclusively expressed on monocytes/macrophages and is widely used as a marker for alternatively activated macrophages. However, the role of CD163 is not yet clear.

Objectives: We sought to examine the function of CD163 in steady-state as well as in sterile and infectious inflammation.

Methods: Expression of CD163 was analyzed under normal and inflammatory conditions in mice. Functional relevance of CD163 was investigated in models of inflammation in wild-type and CD163 mice.

Results: We describe a subpopulation of bone marrow-resident macrophages (BMRMs) characterized by a high expression of CD163 and functionally distinct from classical bone marrow-derived macrophages. Development of CD163 BMRMs is strictly dependent on IFN regulatory factor-8. CD163 BMRMs show a specific transcriptome and cytokine secretion pattern demonstrating a specific immunomodulatory profile of these cells. Accordingly, CD163 mice show a stronger inflammation in allergic contact dermatitis, indicating a regulatory role of CD163. However, CD163 mice are highly susceptible to S aureus infections, demonstrating the relevance of CD163 for antimicrobial defense as well.

Conclusions: Our data indicate that anti-inflammatory and immunosuppressive mechanisms are not necessarily associated with a decreased antimicrobial activity. In contrast, our data define a novel macrophage population that controls overwhelming inflammation on one hand but is also necessary for an effective control of infections on the other hand.
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http://dx.doi.org/10.1016/j.jaci.2020.02.034DOI Listing
November 2020

Spatial attention enhances cortical tracking of quasi-rhythmic visual stimuli.

Neuroimage 2020 03 7;208:116444. Epub 2019 Dec 7.

Centre for Mind/Brain Sciences, University of Trento, via delle Regole 101, 38123, Trento, Italy. Electronic address:

Successfully interpreting and navigating our natural visual environment requires us to track its dynamics constantly. Additionally, we focus our attention on behaviorally relevant stimuli to enhance their neural processing. Little is known, however, about how sustained attention affects the ongoing tracking of stimuli with rich natural temporal dynamics. Here, we used MRI-informed source reconstructions of magnetoencephalography (MEG) data to map to what extent various cortical areas track concurrent continuous quasi-rhythmic visual stimulation. Further, we tested how top-down visuo-spatial attention influences this tracking process. Our bilaterally presented quasi-rhythmic stimuli covered a dynamic range of 4-20 ​Hz, subdivided into three distinct bands. As an experimental control, we also included strictly rhythmic stimulation (10 vs 12 ​Hz). Using a spectral measure of brain-stimulus coupling, we were able to track the neural processing of left vs. right stimuli independently, even while fluctuating within the same frequency range. The fidelity of neural tracking depended on the stimulation frequencies, decreasing for higher frequency bands. Both attended and non-attended stimuli were tracked beyond early visual cortices, in ventral and dorsal streams depending on the stimulus frequency. In general, tracking improved with the deployment of visuo-spatial attention to the stimulus location. Our results provide new insights into how human visual cortices process concurrent dynamic stimuli and provide a potential mechanism - namely increasing the temporal precision of tracking - for boosting the neural representation of attended input.
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http://dx.doi.org/10.1016/j.neuroimage.2019.116444DOI Listing
March 2020

Grey-matter abnormalities in clinical high-risk participants for psychosis.

Schizophr Res 2020 12 15;226:120-128. Epub 2019 Nov 15.

Institute for Neuroscience and Psychology, Univ. of Glasgow, UK; Charité Universitätsmedizin, Department of Child and Adolescent Psychiatry, Berlin, Germany. Electronic address:

The current study examined the presence of abnormalities in cortical grey-matter (GM) in a sample of clinical high-risk (CHR) participants and examined relationships with psychosocial functioning and neurocognition. CHR-participants (n = 114), participants who did not fulfil CHR-criteria (CHR-negative) (n = 39) as well as a group of healthy controls (HC) (n = 49) were recruited. CHR-status was assessed using the Comprehensive Assessment of At-Risk Mental State (CAARMS) and the Schizophrenia Proneness Interview, Adult Version (SPI-A). The Brief Assessment of Cognition in Schizophrenia Battery (BACS) as well as tests for emotion recognition, working memory and attention were administered. In addition, role and social functioning as well as premorbid adjustment were assessed. No significant differences in GM-thickness and intensity were observed in CHR-participants compared to CHR-negative and HC. Circumscribed abnormalities in GM-intensity were found in the visual and frontal cortex of CHR-participants. Moreover, small-to-moderate correlations were observed between GM-intensity and neuropsychological deficits in the CHR-group. The current data suggest that CHR-participants may not show comprehensive abnormalities in GM. We discuss the implications of these findings for the pathophysiological theories of early stage-psychosis as well as methodological issues and the impact of different recruitment strategies.
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http://dx.doi.org/10.1016/j.schres.2019.08.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7774586PMC
December 2020

Magnetoencephalography in Cognitive Neuroscience: A Primer.

Authors:
Joachim Gross

Neuron 2019 10;104(2):189-204

Institute for Biomagnetism and Biosignalanalysis (IBB), University of Muenster, 48149 Muenster, Germany; Otto-Creutzfeldt-Center for Cognitive and Behavioral Neuroscience, University of Muenster, 48149 Muenster, Germany; Centre for Cognitive Neuroimaging (CCNi), University of Glasgow, Glasgow, UK. Electronic address:

Magnetoencephalography (MEG) is an invaluable tool to study the dynamics and connectivity of large-scale brain activity and their interactions with the body and the environment in functional and dysfunctional body and brain states. This primer introduces the basic concepts of MEG, discusses its strengths and limitations in comparison to other brain imaging techniques, showcases interesting applications, and projects exciting current trends into the near future, in a way that might more fully exploit the unique capabilities of MEG.
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http://dx.doi.org/10.1016/j.neuron.2019.07.001DOI Listing
October 2019

Gamma Oscillations Shape Pain in Animals and Humans.

Trends Cogn Sci 2019 Dec 19;23(12):1086. Epub 2019 Oct 19.

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http://dx.doi.org/10.1016/j.tics.2019.09.006DOI Listing
December 2019

Beta-band oscillations play an essential role in motor-auditory interactions.

Hum Brain Mapp 2020 02 22;41(3):656-665. Epub 2019 Oct 22.

Institute for Biomagnetism and Biosignalanalysis, University of Münster, Münster, Germany.

In the human brain, self-generated auditory stimuli elicit smaller cortical responses compared to externally generated sounds. This sensory attenuation is thought to result from predictions about the sensory consequences of self-generated actions that rely on motor commands. Previous research has implicated brain oscillations in this process. However, the specific role of these oscillations in motor-auditory interactions during sensory attenuation is still unclear. In this study, we aimed at addressing this question by using magnetoencephalography (MEG). We recorded MEG in 20 healthy participants during listening to passively presented and self-generated tones. Our results show that the magnitude of sensory attenuation in bilateral auditory areas is significantly correlated with the modulation of beta-band (15-30 Hz) amplitude in the motor cortex. Moreover, we observed a significant directional coupling (Granger causality) in beta-band originating from the motor cortex toward bilateral auditory areas. Our findings indicate that beta-band oscillations play an important role in mediating top-down interactions between motor and auditory cortex and, in our paradigm, suppress cortical responses to predicted sensory input.
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http://dx.doi.org/10.1002/hbm.24830DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7268072PMC
February 2020

A New Unifying Account of the Roles of Neuronal Entrainment.

Curr Biol 2019 09;29(18):R890-R905

Centre for Cognitive Neuroimaging (CCNi), Institute of Neuroscience and Psychology, University of Glasgow, 62 Hillhead Street, Glasgow, G12 8QB, UK. Electronic address:

Rhythms are a fundamental and defining feature of neuronal activity in animals including humans. This rhythmic brain activity interacts in complex ways with rhythms in the internal and external environment through the phenomenon of 'neuronal entrainment', which is attracting increasing attention due to its suggested role in a multitude of sensory and cognitive processes. Some senses, such as touch and vision, sample the environment rhythmically, while others, like audition, are faced with mostly rhythmic inputs. Entrainment couples rhythmic brain activity to external and internal rhythmic events, serving fine-grained routing and modulation of external and internal signals across multiple spatial and temporal hierarchies. This interaction between a brain and its environment can be experimentally investigated and even modified by rhythmic sensory stimuli or invasive and non-invasive neuromodulation techniques. We provide a comprehensive overview of the topic and propose a theoretical framework of how neuronal entrainment dynamically structures information from incoming neuronal, bodily and environmental sources. We discuss the different types of neuronal entrainment, the conceptual advances in the field, and converging evidence for general principles.
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http://dx.doi.org/10.1016/j.cub.2019.07.075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6769420PMC
September 2019

An equation of state for Stockmayer fluids based on a perturbation theory for dipolar hard spheres.

J Chem Phys 2019 Sep;151(10):104102

Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart, Germany.

We develop a perturbation theory for the difference between the Helmholtz energy of a Stockmayer fluid, i.e., a fluid interacting by a Lennard-Jones plus point-dipole potential, and a Lennard-Jones fluid. We show that the difference can be approximated by the perturbational Helmholtz energy contribution of a dipolar hard-sphere fluid with a suitably chosen effective hard-sphere diameter, relative to a hard-sphere fluid with the same effective diameter. We analyze both a third and fourth order perturbation theory, both written as Padé approximations. Several recipes for calculating the hard-sphere diameter are investigated; we find that the Weeks-Chandler-Andersen diameter is most suitable. Results of the perturbation theory are shown to be in good agreement with reference data for the Helmholtz energy, internal energy, and isochoric heat capacity as obtained from molecular simulations performed in this work and to vapor-liquid equilibrium data from the literature. Theoretical predictions of the proposed model are compared to results from the perturbation theory of Gubbins and Twu [Chem. Eng. Sci. 33, 863 (1978)], which is a theory based on a Lennard-Jones reference fluid. We find the theories are in good agreement. Our approach can easily be applied to van der Waals potentials, other than Lennard-Jones potentials. If a dipolar Mie fluid is considered, the approach merely requires calculation of the effective hard-sphere diameter for a Mie potential. We further note that the approach has a reduction in the variable space of the underlying correlation integrals, i.e., the correlation functions of a hard-sphere fluid depend on density only, whereas the Lennard-Jones reference correlation functions depend on density and temperature.
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http://dx.doi.org/10.1063/1.5116912DOI Listing
September 2019

Neural oscillations and connectivity characterizing the state of tonic experimental pain in humans.

Hum Brain Mapp 2020 01 9;41(1):17-29. Epub 2019 Sep 9.

Department of Neurology and TUM-Neuroimaging Center, TUM School of Medicine, Technical University of Munich, Munich, Germany.

Pain is a complex phenomenon that is served by neural oscillations and connectivity involving different brain areas and frequencies. Here, we aimed to systematically and comprehensively assess the pattern of neural oscillations and connectivity characterizing the state of tonic experimental pain in humans. To this end, we applied 10-min heat pain stimuli consecutively to the right and left hand of 39 healthy participants and recorded electroencephalography. We systematically analyzed global and local measures of oscillatory brain activity, connectivity, and graph theory-based network measures during tonic pain and compared them to a nonpainful control condition. Local measures showed suppressions of oscillatory activity at alpha frequencies together with stronger connectivity at alpha and beta frequencies in sensorimotor areas during tonic pain. Furthermore, sensorimotor areas contralateral to stimulation showed significantly increased connectivity to a common area in the medial prefrontal cortex at alpha frequencies. Together, these observations indicate that the state of tonic experimental pain is associated with a sensorimotor-prefrontal network connected at alpha frequencies. These findings represent a step further toward understanding the brain mechanisms underlying long-lasting pain states in health and disease.
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http://dx.doi.org/10.1002/hbm.24784DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7267966PMC
January 2020

Prediction of Adsorption Isotherms and Selectivities: Comparison between Classical Density Functional Theory Based on the Perturbed-Chain Statistical Associating Fluid Theory Equation of State and Ideal Adsorbed Solution Theory.

Langmuir 2019 Sep 26;35(36):11690-11701. Epub 2019 Aug 26.

Institute of Thermodynamics and Thermal Process Engineering , University of Stuttgart , Pfaffenwaldring 9 , 70569 Stuttgart , Germany.

This study gives an assessment of the predictive capability of classical density functional theory (DFT) for adsorption processes of pure substances and mixtures of spherical and nonspherical molecular species. A Helmholtz energy functional based on the perturbed-chain statistical associating fluid theory (PC-SAFT) is applied to calculate isotherms and selectivities of multicomponent adsorption. In order to unambiguously assess the accuracy of the DFT model, we conduct molecular simulations. Monte Carlo (MC) simulations are performed in the grand canonical ensemble using the transition matrix. Two types of systems are studied: a model system, where fluid-fluid and solid-fluid interactions are defined as (single-site) Lennard-Jones interactions, and a more realistic methane--butane mixture in a graphite-like pore. Differences between a slit-shaped and a cylindrical pore geometry are examined for the model system. Adsorption isotherms and selectivities obtained from DFT calculations and MC simulations are found in very good agreement, particularly at high pressures. Capillary condensation observed along adsorption isotherms containing -butane was accurately predicted, both, in equilibrium pressure and in density-increase. Comparisons with results from the ideal adsorbed solution theory are presented, confirming powerful predictions of the DFT approach.
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http://dx.doi.org/10.1021/acs.langmuir.9b02378DOI Listing
September 2019

Brain dysfunction in chronic pain patients assessed by resting-state electroencephalography.

Pain 2019 12;160(12):2751-2765

Department of Neurology, School of Medicine, Technical University of Munich, Munich, Germany.

Chronic pain is a common and severely disabling disease whose treatment is often unsatisfactory. Insights into the brain mechanisms of chronic pain promise to advance the understanding of the underlying pathophysiology and might help to develop disease markers and novel treatments. Here, we systematically exploited the potential of electroencephalography to determine abnormalities of brain function during the resting state in chronic pain. To this end, we performed state-of-the-art analyses of oscillatory brain activity, brain connectivity, and brain networks in 101 patients of either sex suffering from chronic pain. The results show that global and local measures of brain activity did not differ between chronic pain patients and a healthy control group. However, we observed significantly increased connectivity at theta (4-8 Hz) and gamma (>60 Hz) frequencies in frontal brain areas as well as global network reorganization at gamma frequencies in chronic pain patients. Furthermore, a machine learning algorithm could differentiate between patients and healthy controls with an above-chance accuracy of 57%, mostly based on frontal connectivity. These results suggest that increased theta and gamma synchrony in frontal brain areas are involved in the pathophysiology of chronic pain. Although substantial challenges concerning the reproducibility of the findings and the accuracy, specificity, and validity of potential electroencephalography-based disease markers remain to be overcome, our study indicates that abnormal frontal synchrony at theta and gamma frequencies might be promising targets for noninvasive brain stimulation and/or neurofeedback approaches.
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http://dx.doi.org/10.1097/j.pain.0000000000001666DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7195856PMC
December 2019

Simple Acoustic Features Can Explain Phoneme-Based Predictions of Cortical Responses to Speech.

Curr Biol 2019 06 23;29(12):1924-1937.e9. Epub 2019 May 23.

Institute of Neuroscience and Psychology, University of Glasgow, 62 Hillhead Street, Glasgow G12 8QB, UK; Institute for Biomagnetism and Biosignalanalysis, University of Münster, Malmedyweg 15, 48149 Münster, Germany.

When we listen to speech, we have to make sense of a waveform of sound pressure. Hierarchical models of speech perception assume that, to extract semantic meaning, the signal is transformed into unknown, intermediate neuronal representations. Traditionally, studies of such intermediate representations are guided by linguistically defined concepts, such as phonemes. Here, we argue that in order to arrive at an unbiased understanding of the neuronal responses to speech, we should focus instead on representations obtained directly from the stimulus. We illustrate our view with a data-driven, information theoretic analysis of a dataset of 24 young, healthy humans who listened to a 1 h narrative while their magnetoencephalogram (MEG) was recorded. We find that two recent results, the improved performance of an encoding model in which annotated linguistic and acoustic features were combined and the decoding of phoneme subgroups from phoneme-locked responses, can be explained by an encoding model that is based entirely on acoustic features. These acoustic features capitalize on acoustic edges and outperform Gabor-filtered spectrograms, which can explicitly describe the spectrotemporal characteristics of individual phonemes. By replicating our results in publicly available electroencephalography (EEG) data, we conclude that models of brain responses based on linguistic features can serve as excellent benchmarks. However, we believe that in order to further our understanding of human cortical responses to speech, we should also explore low-level and parsimonious explanations for apparent high-level phenomena.
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http://dx.doi.org/10.1016/j.cub.2019.04.067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6584359PMC
June 2019

Applying Interdisciplinary Innovations to Advance Theories of Social Behavior: Response to Van Dessel and Colleagues.

Trends Cogn Sci 2019 06 29;23(6):450-451. Epub 2019 Apr 29.

Institute for Biomagnetism and Biosignalanalysis, University of Münster, Münster, Germany; Centre for Cognitive Neuroimaging, University of Glasgow, Glasgow, UK.

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http://dx.doi.org/10.1016/j.tics.2019.04.001DOI Listing
June 2019

Phase Equilibria of Solid and Fluid Phases from Molecular Dynamics Simulations with Equilibrium and Nonequilibrium Free Energy Methods.

J Chem Theory Comput 2019 Jun 17;15(6):3778-3792. Epub 2019 May 17.

Institute of Thermodynamics and Thermal Process Engineering , University of Stuttgart , Pfaffenwaldring 9 , D-70569 Stuttgart , Germany , www.itt.uni-stuttgart.de.

In this work, we present a methodology to determine phase coexistence lines for atomic and rigid molecular systems with an emphasis on solid-fluid and on solid-solid equilibria. Phase coexistence points are found by computing the absolute free energy for each candidate phase separately. For solid phases, a combination of the extended Einstein crystal and the Einstein molecule method is presented which constitutes a convenient way to compute the absolute free energy with fixed center of mass. We compare results from equilibrium methods-thermodynamic integration and reweighting using the multistate Bennett acceptance ratio estimator (MBAR)-with simulations using a nonequilibrium method and discuss their advantages and disadvantages. Once absolute free energies of different phases are available, they are combined with simulations performed in the isothermal isobaric ensemble and MBAR, which enables efficient, iterative tracing of coexistence lines. The method is applicable to both liquid-solid as well as solid-solid transitions and is comparably simple and convenient to apply since the same method (MBAR) is used to compute free energies and to trace the coexistence line. Furthermore, statistical uncertainties can readily be computed in a transparent manner. We apply the method to an atomic solid (fcc argon) as well as small molecular systems (methanol and water) using the LAMMPS simulation package. Our study shows that all methods can be used to reliably compute the absolute free energy of solid phases, while MBAR is the most flexible method with high statistical efficiency. We find the nonequilibrium method is an attractive choice since it is simple to set up and to postprocess and is, hence, less prone to errors. The presented workflow provides a flexible, efficient, and robust way to compute phase diagrams using openly available software.
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http://dx.doi.org/10.1021/acs.jctc.8b01023DOI Listing
June 2019