Modelling large motion events in fMRI studies of patients with epilepsy

EEG-correlated fMRI can provide localisation information on the generators of epileptiform discharges in patients with focal epilepsy. To increase the technique's clinical potential, it is important to consider ways of optimising the yield of each experiment while minimizing the risk of false-positive activation. Head motion can lead to severe image degradation and result in false-positive activation and is usually worse in patients than in healthy subjects. We performed general linear model fMRI data analysis on simultaneous EEG–fMRI data acquired in 34 cases with focal epilepsy. Signal changes associated with large inter-scan motion events (head jerks) were modelled using modified design matrices that include ‘scan nulling’ regressors. We evaluated the efficacy of this approach by mapping the proportion of the brain for which F-tests across the additional regressors were significant. In 95% of cases, there was a significant effect of motion in 50% of the brain or greater; for the scan nulling effect, the proportion was 36%; this effect was predominantly in the neocortex. We conclude that careful consideration of the motion-related effects in fMRI studies of patients with epilepsy is essential and that the proposed approach can be effective

Simulation of non-linear bearing forces for post-stability investigation

Different types of bearing designs were developed to improve dynamic properties of rotor-bearing systems. Elliptical bearings, multisleeve bearings, tilting pad and other designs such as herringbone groove were utilized to increase resistance to the onset of self excited vibrations. Experimental trials are costly, two alternative methods are used to gain a qualitative insight. The first one creates mathematical model and applies both a digital or an analog computer simulation. The second one investigates phenomena occurring on the laboratory rig with the bearing replaced by an electronic simulating device, working in a feedback loop, which produces forces,which are functions of journal displacement and velocity. The simulated hydrodynamic forces are produced according to assumed characteristics matched to the bearing type. The principal benefit of the analog simulation is that nonlinear characteristics of a subsystem are precisely identified and mathematical methods applied for a wide class of problems are checked on the experimental installation

EEG–fMRI of idiopathic and secondarily generalized epilepsies

We used simultaneous EEG and functional MRI (EEG–fMRI) to study generalized spike wave activity (GSW) in idiopathic and secondary generalized epilepsy (SGE). Recent studies have demonstrated thalamic and cortical fMRI signal changes in association with GSW in idiopathic generalized epilepsy (IGE). We report on a large cohort of patients that included both IGE and SGE, and give a functional interpretation of our findings. Forty-six patients with GSW were studied with EEG–fMRI; 30 with IGE and 16 with SGE. GSW-related BOLD signal changes were seen in 25 of 36 individual patients who had GSW during EEG–fMRI. This was seen in thalamus (60%) and symmetrically in frontal cortex (92%), parietal cortex (76%), and posterior cingulate cortex/precuneus (80%). Thalamic BOLD changes were predominantly positive and cortical changes predominantly negative. Group analysis showed a negative BOLD response in the cortex in the IGE group and to a lesser extent a positive response in thalamus. Thalamic activation was consistent with its known role in GSW, and its detection in individual cases with EEG–fMRI may in part be related to the number and duration of GSW epochs recorded. The spatial distribution of the cortical fMRI response to GSW in both IGE and SGE involved areas of association cortex that are most active during conscious rest. Reduction of activity in these regions during GSW is consistent with the clinical manifestation of absence seizures

Development of head docking device for linac-based radiosurgery with a Neptun 10 PC linac

Stereotactic radiosurgery is a method for focused irradiation of intracranial lesions. Linac-based radiosurgery is currently performed by two techniques: couch mounted and pedestal mounted. In the first technique a device is required to affix the patient's head to the couch and moreover to translate it accurately. Structure of such a device constructed by the authors plus acceptance test performed for evaluation is described in the article. A head docking device has been designed and constructed according to geometry of linac's couch and also desired functions. The device is completely made from aluminum and consists of four major components: attachment bar, lower structure with four movements, upper structure with two movements equipped with a lock, two handles and a mounting ring for stereotactic frame. Translating accuracy, mechanical stability and isocentric accuracy were assessed in the frame of acceptance test. Translating accuracy, mechanical stability and isocentric accuracy were found to be respectively: 1 mm, 1.64 mm and 3.2 mm with accuracy of 95%. According to AAPM report no.54, a head docking device should translate head with an accuracy of 1 mm; this recommendation has been met. Moreover, we have demonstrated that the isocentric accuracy and mechanical stability of the device are sufficient that the device can confidently be used in stereotactic treatment

Independence versus Affiliation: What Determines Entry into Parliamentary Party Groups?

Political parties are often considered essential for structuring parliamentary decisionmaking in democracies. However, many MPs experience spells of being non-affiliated with any parliamentary party group (PPG), either because they were elected as independent candidates or left their PPGs earlier in the legislative term. Whether such non-affiliation periods end with an entry to a PPG, which PPG the legislator enters and how long they remain independent before the entry, as well as the reasons for these patterns, remains relatively unknown. This paper addresses these under-researched questions by examining PPG entry in three Central and Eastern European countries (Lithuania, Poland, and Romania) in the last two decades. We build and test an argument that electoral, office and policy concerns of both the MPs considering the entry and the potential receiving parties play an important role in driving entry. Our findings suggest that legislators’ electoral incentives as a key explanation for their PPG affiliation decisions

Understanding the Complexity of Party Instability in Parliaments

We propose a new typology of parliamentary party switches (switching events) that focuses on three dimensions: (1) the number of MPs and the degree of coordination, (2) the origin of switchers and (3) the destination of switchers – a parliamentary party group (PPG) or independent status. We further distinguish between switches with single and multiple destinations. Our approach sheds new light to party instability in various ways. We elucidate types of party instability to emphasize the complexity of party instability that have eluded the conceptual toolset available thus far. For example, “collective defection” (coordinated movement from one PPG to another), “collective exit” (MPs exiting their parliamentary group to become independent MPs) and “multi-PPG split” (coordinated moves from several PPGs to form a new PPG). Using preliminary data compiled for Instaparty (Party Instability in Parliaments) project from (mostly) Poland and Ireland, we find rich diversity in the forms of parliamentary party instability. While individual defections are much more common than group defections, they are clearly more dominant in Ireland than in Poland; furthermore, switches between PPGs (rather than between PPGs and independent status) have been more common in Poland. Our typology is illustrated by the analysis of the 8th Polish Sejm that provides examples of nearly all single-origin switching events and of most multiorigin ones. The new typology presents the first step of our inquiry into the patterns, causes and consequences of party switching in eight democracies (Estonia, Ireland, Italy, Lithuania, Norway, the Netherlands, Poland and Romania) from 1960s/1990s to early 2020s

Does switching pay off? The impact of parliamentary party instability on individual electoral performance

Members of parliament who change their parliamentary party group (PPG) affiliation can be motivated by a variety of factors but the desire to improve their electoral prospects is often argued to be the among the most important. But does switching PPG affiliation improve or damage the electoral performance of those involved? We study the changes in electoral performance of Polish MPs involved in parliamentary party instability since the mid-1990s using an original dataset on all instances of switching compiled by the INSTAPARTY (Party Instability in Parliaments, https://instapartyproject.com) project. In addition to analyzing whether the MPs run for the parliament again in the following election, we zoom in on their electoral performance in terms of personal preference votes. We consider the electoral dividends of different types of switching and find that the effect of switching on personal electoral performance depends on the type of switching MPs were involved in