About phase transitions in Bose gases at constant density and constant pressure

The phase transitions in Bose gases at constant volume and constant pressure are considered. New results for the chemical potential, the effective Landau-Ginzburg free energy and the equation of state of the Bose condensate in ideal Bose gases with a general form of the energy spectrum are presented. Unresolved problems are discussed.Comment: 9 pages, no figs. AIP Proc. of Leiden Workshop (2004) on Realistic Models of Astrophysical Matte

Übersetzung, kulturelle Adaptation und Test-Retest-Reliabilität der deutschen Version des Headache Disability Questionnaire

Einleitung: Kopfschmerzen führen zu häufigen Einschränkungen im Alltag. Spezifische Fragebögen dienen als Messinstrumente zur Erfassung solcher kopfschmerzbedingten Einschränkungen. Im deutschsprachigen Raum besteht zurzeit kein ideales Messinstrument, das die Schwere der Einschränkung durch Kopfschmerzen innerhalb einer akzeptablen Recall-Zeit erfasst und zuverlässig misst. Der Headache Disability Questionnaire (HDQ) ist ein englischsprachiges Messinstrument, das die Anforderungen eines zuverlässigen Fragebogens für Kopfschmerzen erfüllt. Es besteht keine validierte deutsche Version des HDQ. Ziel: Übersetzung des HDQ in die deutsche Sprache, kulturübergreifende Adaption an die deutschsprachige Population sowie Untersuchung seiner Test-Retest-Reliabilität. Methode: Der HDQ wurde zuerst in einem 2-Phasen-Querschnittstudiendesign nach internationalen Richtlinien ins Deutsche übersetzt und adaptiert (HDQ-G). 12 erwachsene deutsche Muttersprachler*innen nahmen an kognitiven Interviews zur Verständlichkeit einer präfinalen deutschen Version des HDQ teil. Anschließend wurden Anpassungen in Absprache mit dem Erstautor der Originalversion und einem Expertenkomitee vorgenommen. Danach wurde die Test-Retest-Reliabilität des HDQ-G mittels Intraklassenkorrelationskoeffizienten (ICC) mithilfe von 29 erwachsenen Patient*innen mit Kopfschmerzen evaluiert und mittels Bland-Altman-Plot bildlich dargestellt. Die Teilnehmenden nahmen in einem Zeitraum von 2–14 Tagen je zweimal an einer Online-Umfrage mit der finalen Version teil. Ergebnisse: Alle Schritte des Übersetzungsprozesses wurden eingehalten und die finale deutsche Version des HDQ wurde mit wenigen Ergänzung fertiggestellt. Der HDQ-G zeigte eine sehr gute Test-Retest-Reliabilität mit einem ICC = 0,89 (95 %-Konfidenzintervall (KI) von 0,77–0,95). Die mittlere Differenz beider Umfragen lag bei + 1,72 Punkten, 95 % aller Werte lagen zwischen + 10,77 und -7,33 Punkten. Schlussfolgerung: Die originale Version des HDQ wurde übersetzt und für die Verwendung bei der erwachsenen deutschsprachigen Population im ambulanten physiotherapeutischen Setting adaptiert. Der HDQ-G zeigte eine sehr gute Test-Retest-Reliabilität und akzeptable Übereinstimmung bei allgemeinen Patient*innen mit Kopfschmerzen im physiotherapeutischen Setting. Zusätzliche Studien sind notwendig, um weitere wissenschaftliche Gütekriterien des HDQ zu untersuchen

In vivo imaging of the nucleus of the solitary tract with Magnetization Transfer at 7 Tesla

The nucleus of the solitary tract (NTS) is a nuclei complex with, among others, a high concentration of noradrenergic neurons (including the noradrenergic subnuclei named A1 and A2) in the medulla. The NTS regulates several cognitive, neuroendocrine and autonomic functions. No method currently exists to anatomically visualize the NTS in vivo. Several noradrenergic and dopaminergic nuclei have been successfully imaged using Magnetization Transfer (MT) contrast manipulation. We therefore hypothesized that an efficient, high-resolution MT-weighted sequence at 7 T might successfully image the NTS. In this study, we found a hyperintensity, similar to hyperintensities found in other noradrenergic and dopaminergic nuclei, consistent with the expected NTS location, and specific to the MT-weighted images. The localization of the hyperintensity was found to be consistent between individuals and slices and in good correspondence to a histological atlas and a meta-analytic map of fMRI-based NTS activation. We conclude that the method may, for the first time, achieve NTS imaging in vivo and within a clinically-feasible acquisition time. To facilitate NTS research at lower field strengths, an NTS template was created and made publicly available

Physiologically informed dynamic causal modeling of fMRI data

AbstractThe functional MRI (fMRI) signal is an indirect measure of neuronal activity. In order to deconvolve the neuronal activity from the experimental fMRI data, biophysical generative models have been proposed describing the link between neuronal activity and the cerebral blood flow (the neurovascular coupling), and further the hemodynamic response and the BOLD signal equation. These generative models have been employed both for single brain area deconvolution and to infer effective connectivity in networks of multiple brain areas. In the current paper, we introduce a new fMRI model inspired by experimental observations about the physiological underpinnings of the BOLD signal and compare it with the generative models currently used in dynamic causal modeling (DCM), a widely used framework to study effective connectivity in the brain. We consider three fundamental aspects of such generative models for fMRI: (i) an adaptive two-state neuronal model that accounts for a wide repertoire of neuronal responses during and after stimulation; (ii) feedforward neurovascular coupling that links neuronal activity to blood flow; and (iii) a balloon model that can account for vascular uncoupling between the blood flow and the blood volume. Finally, we adjust the parameterization of the BOLD signal equation for different magnetic field strengths. This paper focuses on the form, motivation and phenomenology of DCMs for fMRI and the characteristics of the various models are demonstrated using simulations. These simulations emphasize a more accurate modeling of the transient BOLD responses — such as adaptive decreases to sustained inputs during stimulation and the post-stimulus undershoot. In addition, we demonstrate using experimental data that it is necessary to take into account both neuronal and vascular transients to accurately model the signal dynamics of fMRI data. By refining the models of the transient responses, we provide a more informed perspective on the underlying neuronal process and offer new ways of inferring changes in local neuronal activity and effective connectivity from fMRI

Feasibility of Haralick's Texture Features for the Classification of Chromogenic In-situ Hybridization Images

This paper presents a proof of concept for the usefulness of second-order texture features for the qualitative analysis and classification of chromogenic in-situ hybridization whole slide images in high-throughput imaging experiments. The challenge is that currently, the gold standard for gene expression grading in such images is expert assessment. The idea of the research team is to use different approaches in the analysis of these images that will be used for structural segmentation and functional analysis in gene expression. The article presents such perspective idea to select a number of textural features that are going to be used for classification. In our experiment, natural grouping of image samples (tiles) depending on their local texture properties was explored in an unsupervised classification procedure. The features are reduced to two dimensions with fuzzy c-means clustering. The overall conclusion of this experiment is that Haralick features are a viable choice for classification and analysis of chromogenic in-situ hybridization image data. The principal component analysis approach produced slightly more "understandable" from an annotator's point of view classes.Comment: 4 pages, 1 figur

Cortical lamina-dependent blood volume changes in human brain at 7T

Cortical layer-dependent high (sub-millimeter) resolution functional magnetic resonance imaging (fMRI) in human or animal brain can be used to address questions regarding the functioning of cortical circuits, such as the effect of different afferent and efferent connectivities on activity in specific cortical layers. The sensitivity of gradient echo (GE) blood oxygenation level-dependent (BOLD) responses to large draining veins reduces its local specificity and can render the interpretation of the underlying laminar neural activity impossible. The application of the more spatially specific cerebral blood volume (CBV)-based fMRI in humans has been hindered by the low sensitivity of the noninvasive modalities available. Here, a vascular space occupancy (VASO) variant, adapted for use at high field, is further optimized to capture layer-dependent activity changes in human motor cortex at sub-millimeter resolution. Acquired activation maps and cortical profiles show that the VASO signal peaks in gray matter at 0.8–1.6 mm depth, and deeper compared to the superficial and vein-dominated GE-BOLD responses. Validation of the VASO signal change versus well-established iron-oxide contrast agent based fMRI methods in animals showed the same cortical profiles of CBV change, after normalization for lamina-dependent baseline CBV. In order to evaluate its potential of revealing small lamina-dependent signal differences due to modulations of the input-output characteristics, layer-dependent VASO responses were investigated in the ipsilateral hemisphere during unilateral finger tapping. Positive activation in ipsilateral primary motor cortex and negative activation in ipsilateral primary sensory cortex were observed. This feature is only visible in high-resolution fMRI where opposing sides of a sulcus can be investigated independently because of a lack of partial volume effects. Based on the results presented here, we conclude that VASO offers good reproducibility, high sensitivity and lower sensitivity than GE-BOLD to changes in larger vessels, making it a valuable tool for layer-dependent fMRI studies in humans

Effects of MP2RAGE B\u3csub\u3e1\u3c/sub\u3e\u3csup\u3e+\u3c/sup\u3e sensitivity on inter-site T\u3csub\u3e1\u3c/sub\u3e reproducibility and hippocampal morphometry at 7T

Most neuroanatomical studies are based on T -weighted MR images, whose intensity profiles are not solely determined by the tissue\u27s longitudinal relaxation times (T ), but also affected by varying non-T contributions, hampering data reproducibility. In contrast, quantitative imaging using the MP2RAGE sequence, for example, allows direct characterization of the brain based on the tissue property of interest. Combined with 7 Tesla (7T) MRI, this offers unique opportunities to obtain robust high-resolution brain data characterized by a high reproducibility, sensitivity and specificity. However, specific MP2RAGE parameter choices – e.g., to emphasize intracortical myelin-dependent contrast variations – can substantially impact image quality and cortical analyses through remnants of B -related intensity variations, as illustrated in our previous work. To follow up on this: we (1) validate this protocol effect using a dataset acquired with a particularly B insensitive set of MP2RAGE parameters combined with parallel transmission excitation; and (2) extend our analyses to evaluate the effects on hippocampal morphometry. The latter remained unexplored initially, but can provide important insights related to generalizability and reproducibility of neurodegenerative research using 7T MRI. We confirm that B inhomogeneities have a considerably variable effect on cortical T estimates, as well as on hippocampal morphometry depending on the MP2RAGE setup. While T differed substantially across datasets initially, we show the inter-site T comparability improves after correcting for the spatially varying B field using a separately acquired Sa2RAGE B map. Finally, removal of B residuals affects hippocampal volumetry and boundary definitions, particularly near structures characterized by strong intensity changes (e.g. cerebral spinal fluid). Taken together, we show that the choice of MP2RAGE parameters can impact T comparability across sites and present evidence that hippocampal segmentation results are modulated by B inhomogeneities. This calls for careful (1) consideration of sequence parameters when setting acquisition protocols, as well as (2) acquisition of a B map to correct MP2RAGE data for potential B variations to allow comparison across datasets. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 + + + + + + + +

Tonotopic maps in human auditory cortex using arterial spin labeling

A tonotopic organization of the human auditory cortex (AC) has been reliably found by neuroimaging studies. However, a full characterization and parcellation of the AC is still lacking. In this study, we employed pseudo-continuous arterial spin labeling (pCASL) to map tonotopy and voice selective regions using, for the first time, cerebral blood flow (CBF). We demonstrated the feasibility of CBF-based tonotopy and found a good agreement with BOLD signal-based tonotopy, despite the lower contrast-to-noise ratio of CBF. Quantitative perfusion mapping of baseline CBF showed a region of high perfusion centered on Heschl's gyrus and corresponding to the main high-low-high frequency gradients, co-located to the presumed primary auditory core and suggesting baseline CBF as a novel marker for AC parcellation. Furthermore, susceptibility weighted imaging was employed to investigate the tissue specificity of CBF and BOLD signal and the possible venous bias of BOLD-based tonotopy. For BOLD only active voxels, we found a higher percentage of vein contamination than for CBF only active voxels. Taken together, we demonstrated that both baseline and stimulus-induced CBF is an alternative fMRI approach to the standard BOLD signal to study auditory processing and delineate the functional organization of the auditory cortex. Hum Brain Mapp, 2016. © 2016 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc

Neurodegenerative and functional signatures of the cerebellar cortex in m.3243A \u3e G patients

Mutations of the mitochondrial DNA are an important cause of inherited diseases that can severely affect the tissue\u27s homeostasis and integrity. The m.3243A \u3e G mutation is the most commonly observed across mitochondrial disorders and is linked to multisystemic complications, including cognitive deficits. In line with in vitro experiments demonstrating the m.3243A \u3e G\u27s negative impact on neuronal energy production and integrity, m.3243A \u3e G patients show cerebral grey matter tissue changes. However, its impact on the most neuron dense, and therefore energy-consuming brain structure - the cerebellum - remains elusive. In this work, we used high-resolution structural and functional data acquired using 7 T MRI to characterize the neurodegenerative and functional signatures of the cerebellar cortex in m.3243A \u3e G patients. Our results reveal altered tissue integrity within distinct clusters across the cerebellar cortex, apparent by their significantly reduced volume and longitudinal relaxation rate compared with healthy controls, indicating macroscopic atrophy and microstructural pathology. Spatial characterization reveals that these changes occur especially in regions related to the frontoparietal brain network that is involved in information processing and selective attention. In addition, based on resting-state functional MRI data, these clusters exhibit reduced functional connectivity to frontal and parietal cortical regions, especially in patients characterized by (i) a severe disease phenotype and (ii) reduced information-processing speed and attention control. Combined with our previous work, these results provide insight into the neuropathological changes and a solid base to guide longitudinal studies aimed to track disease progression