Spatio-temporal generation of large-scale hazardous events that may cause flooding

This thesis treats the generation of weather scenarios that may cause flooding, generally referred to as events, within the context of flood risk. A key concept for the risk approach is that not only hazardous events are generated, but that realistic probabilities, or frequencies, are connected to the events. The purpose of this thesis is to provide some methodological improvements on flood hazard generators and to bring into discussion some useful concepts with regards to spatio-temporal challenges. The flood risk approach is largely data driven. The methods used in this thesis start from obtained data sets, provided by others. General computer algorithms and statistical models are used to generate hypothetical, or `synthetic' data sets. These synthetic data sets are investigated and analysed using computational code. The starting point is the generation of a large synthetic set of pan-European river discharge events, spread out over several hundreds of locations in Europe. Some methodological advances are provided, which allow moving discharge waves to be tracked throughout all major river basins in Europe. A key point in the used methodology is to capture the spatial dependence between events occurring at different locations, which will be referred to as the static spatio-temporal approach. Compared to a local approach, where each location is considered individually, the gains of considering spatial dependence seem rather clear. However, it appears that the static spatio-temporal approach does not work well with an event-based approach, since this methodology implicitly puts boundaries on the procedure of spatio-temporal event identification. Therefore, the next step was the development of a generator that could provide large synthetic sets of precipitation events, over the entire Atlantic sea and Europe. A key point in the methodology used here is that not only the events are dynamic, as their movement is tracked, but also the event descriptors are dynamic. Hence, here the dynamic spatio-temporal approach is introduced, which implies the generator methodology moved beyond generation at a fixed set of locations. The methodological framework is established, which allows a first version of such a dynamic generator, with the potential to be applied globally. And some exploration is provided of methodological extensions that allow to treat multiple variables concurrently in a compound framework. With the newly introduced complexity of the dynamic generator, the final step was to start generating big synthetic data sets and to thoroughly test what the generator produced. A comprehensive sensitivity analysis provides some first insights into the behaviour of the generator, which allow to understand two key concepts. First, with the dynamic spatio-temporal approach, spatial coherence of extremes comes naturally. This contrasts with the static spatio-temporal approach where spatial coherence of extremes has to be assumed prior to the modelling and is typically done by the application of a spatial process. Second, for any location, the dynamic spatio-temporal approach allows to more directly include events occurring in the area surrounding a location to compute extremes at that particular location. Relatively short data records are a standard limitation for the risk approach, whereby this `dynamic expansion of information' may be of help. The provided methodological advances and new concepts may help the way forward to the generation of global hazard events that may cause flooding. Large-scale, coherent event sets allow interactions and system behaviour to be studied, which is a main requirement to be able to compute the system risk. In addition, an interesting outlook is provided for future research. The dynamic spatio-temporal approach may in the future be able to provide not only spatially coherent extremes, but also temporally coherent extremes. This could be a first step towards credible global flood risk time series, which could be a very useful tool, in the current predicament of global climate change

Exclusive enteral nutrition mediates gut microbial and metabolic changes that are associated with remission in children with Crohn’s disease

GD and AWW receive core funding support from the Scottish Government’s Rural and Environmental Science and Analytical Services (RESAS) Division. JW was funded by the Wellcome Trust [Grant No. 098051]. JVL is funded by MRC New Investigator Grant (MR/P002536/1) and ERC Starting Grant (715662). JK is funded by NIHR: II-OL-1116-10027, NIH: R01-CA204403-01A1, Horizon H2020: ITN GROWTH. Imperial Biomedical Research Centre, SAGES research grant. Infrastructure support for this research was provided by the NIHR Imperial biomedical Research Centre (BRC). Microbiota analyses were carried out using the Maxwell computer cluster at the University of Aberdeen. We thank the Illumina MiSeq team at the Wellcome Sanger Institute for their assistance. This work was partially described in the Ph.D. thesis of KD (Retrieved 2020, Pediatric inflammatory bowel disease Monitoring, nutrition and surgery, https://pure.uva.nl/ws/files/23176012/Thesis_complete_.pdf).Peer reviewedPublisher PD

The Distressed Brain: A Group Blind Source Separation Analysis on Tinnitus

Background: Tinnitus, the perception of a sound without an external sound source, can lead to variable amounts of distress. Methodology: In a group of tinnitus patients with variable amounts of tinnitus related distress, as measured by the Tinnitus Questionnaire (TQ), an electroencephalography (EEG) is performed, evaluating the patients ’ resting state electrical brain activity. This resting state electrical activity is compared with a control group and between patients with low (N = 30) and high distress (N = 25). The groups are homogeneous for tinnitus type, tinnitus duration or tinnitus laterality. A group blind source separation (BSS) analysis is performed using a large normative sample (N = 84), generating seven normative components to which high and low tinnitus patients are compared. A correlation analysis of the obtained normative components ’ relative power and distress is performed. Furthermore, the functional connectivity as reflected by lagged phase synchronization is analyzed between the brain areas defined by the components. Finally, a group BSS analysis on the Tinnitus group as a whole is performed. Conclusions: Tinnitus can be characterized by at least four BSS components, two of which are posterior cingulate based, one based on the subgenual anterior cingulate and one based on the parahippocampus. Only the subgenual component correlates with distress. When performed on a normative sample, group BSS reveals that distress is characterized by two anterior cingulate based components. Spectral analysis of these components demonstrates that distress in tinnitus is relate

Prefrontal Cortex Based Sex Differences in Tinnitus Perception: Same Tinnitus Intensity, Same Tinnitus Distress, Different Mood

BACKGROUND: Tinnitus refers to auditory phantom sensation. It is estimated that for 2% of the population this auditory phantom percept severely affects the quality of life, due to tinnitus related distress. Although the overall distress levels do not differ between sexes in tinnitus, females are more influenced by distress than males. Typically, pain, sleep, and depression are perceived as significantly more severe by female tinnitus patients. Studies on gender differences in emotional regulation indicate that females with high depressive symptoms show greater attention to emotion, and use less anti-rumination emotional repair strategies than males. METHODOLOGY: The objective of this study was to verify whether the activity and connectivity of the resting brain is different for male and female tinnitus patients using resting-state EEG. CONCLUSIONS: Females had a higher mean score than male tinnitus patients on the BDI-II. Female tinnitus patients differ from male tinnitus patients in the orbitofrontal cortex (OFC) extending to the frontopolar cortex in beta1 and beta2. The OFC is important for emotional processing of sounds. Increased functional alpha connectivity is found between the OFC, insula, subgenual anterior cingulate (sgACC), parahippocampal (PHC) areas and the auditory cortex in females. Our data suggest increased functional connectivity that binds tinnitus-related auditory cortex activity to auditory emotion-related areas via the PHC-sgACC connections resulting in a more depressive state even though the tinnitus intensity and tinnitus-related distress are not different from men. Comparing male tinnitus patients to a control group of males significant differences could be found for beta3 in the posterior cingulate cortex (PCC). The PCC might be related to cognitive and memory-related aspects of the tinnitus percept. Our results propose that sex influences in tinnitus research cannot be ignored and should be taken into account in functional imaging studies related to tinnitus

Dissecting Auditory Verbal Hallucinations into Two Components: Audibility (Gedankenlautwerden) and Alienation (Thought Insertion)

This study proposes a theoretical framework which dissects auditory verbal hallucinations (AVH) into 2 essential components: audibility and alienation. Audibility, the perceptual aspect of AVH, may result from a disinhibition of the auditory cortex in response to self-generated speech. In isolation, this aspect leads to audible thoughts: Gedankenlautwerden. The second component is alienation, which is the failure to recognize the content of AVH as self-generated. This failure may be related to the fact that cerebral activity associated with AVH is predominantly present in the speech production area of the right hemisphere. Since normal inner speech is derived from the left speech area, an aberrant source may lead to confusion about the origin of the language fragments. When alienation is not accompanied by audibility, it will result in the experience of thought insertion. The 2 hypothesized components are illustrated using case vignettes. Copyright (C) 2010 S. Karger AG, Base

Isolation and characterization of an adipokinetic hormone release-inducing factor in locusts: The crustacean cardioactive peptide

A methanolic extract of 700 desert locust (Schistocerca gregaria) brains contains several factors that stimulate the in vitro release of adipokinetic hormone (AKH) by glandular cells of locust (Locusta migratoria and Schistocerca gregaria) corpora cardiaca. The most potent one has now been fully identified. Matrix-assisted laser desorption ionization mass spectrometry-time of flight analysis revealed a mass of 954.6 Da. The primary structure of the peptide, Pro-Phe-Cys-Asn-Ala-Phe-Thr-Gly-Cys-NH2, appeared identical to that of a previously identified crustacean cardioactive peptide. This myotropin was first isolated from the shore crab, Carcinus maenas, and later from several insect species, but was never reported in the context of AKH release.status: publishe

Treatment of Alice in Wonderland Syndrome and Verbal Auditory Hallucinations Using Repetitive Transcranial Magnetic Stimulation:A Case Report with fMRI Findings

Background: Alice in Wonderland syndrome (AIWS) is a rare cluster of CNS symptoms characterized by visual distortions (i.e. metamorphopsias), body image distortions, time distortions, and deja experiences. Verbal auditory hallucinations (VAHs) are the most prevalent type of hallucination in adults with or without a history of psychiatric illness. Here, we report the case of a woman with AIWS, long-lasting VAHs, and various additional perceptual and mood symptoms. Methods: Semi-structured interviews were used to assess symptoms, and functional MRI (fMRI) was employed to localize cerebral activity during self-reported VAHs. Treatment consisted of repetitive transcranial magnetic stimulation (rTMS) at a frequency of 1 Hz at T3P3, overlying Brodmann's area 40. Results: Activation during VAHs was observed bilaterally in the basal ganglia, the primary auditory cortex, the association auditory cortex, the temporal poles, and the anterior cingulated gyrus. The left and right inferior frontal gyri (Broca's area and its contralateral homologue) were involved, along with the dorsolateral prefrontal cortex. Interestingly, synchronized activation was observed in the primary visual cortex (areas V1 and V2), and the bilateral dorsal visual cortex. The higher visual association cortex also showed significant, but less prominent, activation. During the second week of rTMS treatment, not only the VAHs, but also the other sensory deceptions/distortions and mood symptoms showed complete remission. The patient remained free of any symptoms during a 4-month follow-up phase. After 8 months, when many of the original symptoms had returned, a second treatment phase with rTMS was again followed by complete remission. Conclusions: This case indicates that VAHs and metamorphopsias in AIWS are associated with synchronized activation in both auditory and visual cortices. It also indicates that local rTMS treatment may have global therapeutic effects, suggesting an effect on multiple brain regions in a distributed network. Although a placebo effect cannot be ruled out, this case warrants further investigation of the effects of rTMS treatment in AIWS. Copyright (C) 2011 S. Karger AG, Base

Deactivation of the Parahippocampal Gyrus Preceding Auditory Hallucinations in Schizophrenia

Objective: Activation in a network of language-related regions has been reported during auditory verbal hallucinations. It remains unclear, however, how this activation is triggered. Identifying brain regions that show significant signal changes preceding auditory hallucinations might reveal the origin of these hallucinations. Method: Twenty-four patients with a psychotic disorder indicated the presence of auditory verbal hallucinations during 3-Tesla functional magnetic resonance imaging by squeezing a handheld balloon. A one-sample t test was performed to reveal groupwise activation during hallucinations. To enable analysis of brain activation 6 to 0 seconds preceding hallucinations, a tailored "selective averaging" method, without any a priori assumptions concerning the hemodynamic response profile, was performed. To control for motor-related activation, 15 healthy comparison subjects squeezed a balloon at matched time intervals. Results: Groupwise analysis during auditory verbal hallucinations revealed brain activation in bilateral (right more than left) language-related regions and bilateral motor regions. Prominent deactivation preceding these hallucinations was observed in the left parahippocampal gyrus. In addition, significant deactivation preceding hallucinations was found in the left superior temporal, right inferior frontal, and left middle frontal gyri as well as in the right insula and left cerebellum. No significant signal changes were revealed prior to the matched balloon squeezing among the comparison subjects. Conclusions: Auditory verbal hallucinations in patients with a psychotic disorder are consistently preceded by deactivation of the parahippocampal gyrus. The para-hippocampus has been hypothesized to play a central role in memory recollection, sending information from the hippocampus to the association areas. Dysfunction of this region could trigger inadequate activation of right language areas during auditory hallucinations

The Same or Different? A Phenomenological Comparison of Auditory Verbal Hallucinations in Healthy and Psychotic Individuals

Objective: Whereas auditory verbal hallucinations (AVHs) are most characteristic of schizophrenia, their presence has frequently been described in a continuum, ranging from severely psychotic patients to schizotypal personality disorder patients to otherwise healthy participants. It remains unclear whether AVHs at the outer borders of this spectrum are indeed the same phenomenon. Furthermore, specific characteristics of AVHs may be important indicators of a psychotic disorder. Method: To investigate differences and similarities in AVHs in psychotic and nonpsychotic individuals, the phenomenology of AVHs in 118 psychotic outpatients was compared to that in 11 otherwise healthy individuals, both experiencing AVHs at least once a month. The study was performed between September 2007 and March 2010 at the University Medical Center, Utrecht, the Netherlands. Characteristics of AVHs were quantified using the Psychotic Symptoms Rating Scales Auditory Hallucinations subscale. Results: The perceived location of voices (inside/outside the head), the number of voices, loudness, and personification did not differentiate between psychotic and healthy individuals. The most prominent differences between AVHs in healthy and psychotic individuals were the emotional valence of the content, the frequency of AVHs, and the control subjects had over their AVHs (all P values <.001). Age at onset of AVHs was at a significantly younger age in the healthy individuals (P <.001). In our sample, the negative emotional valence of the content of AVHs could accurately predict the presence of a psychotic disorder in 88% of the participants. Conclusions: We cannot ascertain whether AVHs at the outer borders of the spectrum should be considered the same phenomenon, as there are both similarities and differences. The much younger age at onset of AVHs in the healthy subjects compared to that in psychotic patients may suggest a different pathophysiology. The high predictive value of the emotional content of voices implies that inquiring after the emotional content of AVHs may be a crucial step in the diagnosis of psychotic disorders in individuals hearing voices. J Clin Psychiatry 2011;72(3):320-325 (C) Copyright 2011 Physicians Postgraduate Press, Inc