Lund University Publications
Not a member yet
244244 research outputs found
Sort by
Post-hoc reweighting of hadron production in the Lund string model
No full textWe present a method for reweighting flavor selection in the Lund string fragmentation model. This is the process of calculating and applying event weights enabling fast and exact variation of hadronization parameters on pre-generated event samples. The procedure is post hoc, requiring only a small amount of additional information stored per event, and allowing for efficient estimation of hadronization uncertainties without re-peated simulation. Weight expressions are derived from the hadronization algorithm itself, and validated against direct simulation for a wide range of observables and parameter shifts. The hadronization algorithm can be viewed as a hierarchical Markov process with stochastic rejections, a structure common to many complex simulations outside of high-energy physics. This perspective makes the method modular, extensible, and potentially transferable to other domains. We demonstrate the approach in PYTHIA 8, including both coverage considerations and timing benefits. For the purpose of this pa-per, our goal is to develop and demonstrate the the formalism, and we therefore exclude several model variations for baryon production (popcorn model, junction production) needed for proton collisions. These will be the topic of a future paper
Late Deprescribing of Angiotensin-Converting-Enzyme Inhibitors and Renin-Angiotensin Blockers in Patients with Advanced Cancer Receiving Palliative Care
No full textBackground: Treatment with antihypertensives in patients with advanced cancer is often continued until very late in the disease trajectory, despite a considerable risk of hypotension. Objectives: The aim of this study was to investigate the time of deprescribing of antihypertensive agents in patients with cancer receiving palliative care during their last year of life. The monitoring of blood pressure (BP) during treatment was also studied. Design: Retrospective cohort study. Setting/Subjects: Medical records of all patients admitted during a three-year period to a home care unit in Stockholm, Sweden, and now deceased were screened for antihypertensive agents. To create a homogenous cohort, only agents of the renin-angiotensin system (ATC-code C09) were included. Measurements: Data for time of deprescribing and monitoring of BP were collected. Results: Of 1501 deceased patients, 353 had been treated with agents of the renin-angiotensin system for hypertension and had a primary diagnosis of cancer. BP was measured before deprescribing in 169 patients (47.9%). In 102 patients (28.9%), antihypertensive treatment continued up to the last seven days of life. For 27 patients (7.6%), the treatment had not been deprescribed. In 184 patients (52, 1%), BP was not followed up despite continued antihypertensive treatment. All 27 patients whose treatment was never deprescribed were in this group. Conclusions: This study shows that antihypertensive treatment is often deprescribed late or not at all in patients with advanced cancer. Monitoring BP in patients treated with antihypertensives in palliative care may facilitate making the decision to deprescribe them in time
Tolerance Proportionality and Computational Stability in Adaptive Parallel-in-Time Runge–Kutta Methods
No full textIn this paper, we investigate how adaptive time-integration strategies can be effectively combined with parallel-in-time numerical methods for solving systems of ordinary differential equations. Our focus is particularly on their influence on tolerance proportionality. We examine various grid-refinement strategies within the multigrid reduction-in-time (MGRIT) framework. Our results show that a simple adjustment to the original refinement factor can substantially improve computational stability and reliability. Through numerical experiments on standard test problems using the XBraid library, we demonstrate that parallel-in-time solutions closely match their sequential counterparts. Moreover, with the use of multiple processors, computing time can be significantly reduced
Footprints of Worldwide Adaptation in Structured Populations of Drosophila melanogaster Through the Expanded DEST 2.0 Genomic Resource
No full textLarge-scale genomic resources can place genetic variation into an ecologically informed context. To advance our understanding of the population genetics of the fruit fly Drosophila melanogaster, we present an expanded release of the community-generated population genomics resource Drosophila Evolution over Space and Time (DEST 2.0; https://dest.bio/). This release includes 530 high-quality pooled libraries from flies collected across six continents over more than a decade (2009 to 2021), most at multiple time points per year; 211 of these libraries are sequenced and shared here for the first time. We used this enhanced resource to elucidate several aspects of the species' demographic history and identify novel signs of adaptation across spatial and temporal dimensions. For example, we showed that the spatial genetic structure of populations is stable over time, but that drift due to seasonal contractions of population size causes populations to diverge over time. We identified signals of adaptation that vary between continents in genomic regions associated with xenobiotic resistance, consistent with independent adaptation to common pesticides. Moreover, by analyzing samples collected during spring and fall across Europe, we provide new evidence for seasonal adaptation related to loci associated with pathogen response. Furthermore, we have also released an updated version of the DEST genome browser. This is a useful tool for studying spatiotemporal patterns of genetic variation in this classic model system
Neuroinflammation in Huntington's disease : Causes, consequences, and treatment strategies
No full textHuntington's disease (HD) is a progressive neurodegenerative disorder, and increasing evidence suggests that inflammation, both central and peripheral, plays a role in disease progression. Neurohistology and neuroimaging studies illustrate neuroinflammatory processes as part of HD pathophysiology. Furthermore, studies of blood and cerebrospinal fluid from HD patients show altered levels of inflammatory markers and immune cell populations that could influence neuroinflammation and the neurodegenerative process. Here, we review findings contributing to our understanding of the significance of immune activation in HD pathology. We discuss evidence of intrinsic effects of mutant huntingtin within immune cells and central immune alterations that contribute to neuroinflammation and neurodegeneration. We address the roles of central immune cells, as well as the potential contributions of peripheral signals and cell types in HD immune activation. We further discuss opportunities and challenges in utilizing immune-modulation strategies for future treatment approaches. A better understanding of neuroimmune interactions in HD can provide insights for manipulating these responses, potentially facilitating the development of therapies aimed at reducing the impact of neuroinflammatory and degenerative processes
Familial Risk of Wolff-Parkinson-White Syndrome a Nationwide Family Study in Sweden
No full textBACKGROUND: Wolff-Parkinson-White (WPW) syndrome is a rare cardiac disorder that predispose to supraventricular arrhythmias. Prognosis is usually benign, yet there is an increased lifetime risk of sudden death. While typically sporadic, familial clustering has been reported. This study aimed to assess the risk of WPW, arrhythmias, and mortality among siblings of individuals with WPW.METHODS: This population-based sibling cohort included 5,338,434 individuals born in Sweden (1932-2018), with 3,172 WPW cases identified from the Swedish National Patient Registers. Familial risks among siblings were assessed using incidence rate ratios (IRRs) and adjusted subdistributional hazard ratios (SHRs). Sensitivity analyses excluded syndromic WPW and cases without electrophysiologic procedural confirmation.RESULTS: Although familial occurrence of WPW was exceedingly rare with only 14 of 3,172 cases (0.4%; ≈0.0003% of the total population), siblings of affected individuals showed a significantly higher rate of WPW diagnosis (0.121 vs. 0.032 per 1,000 person-years; IRR 3.83; 95%CI 2.27-6.46; p<0.001) translating to an almost fourfold higher adjusted risk (SHR 3.79; 95%CI 1.81-7.97; p<0.001). Risks of atrial fibrillation (SHR 1.19; 95%CI 1.05-1.35; p<0.01) and ventricular arrhythmias (SHR 1.84; 95%CI 1.45-2.35; p<0.001) were also higher, whereas all-cause mortality was comparable irrespective of sibling history (HR 1.01; 95% CI 0.92-1.11; p=0.88).CONCLUSIONS: WPW features familial aggregation and increased arrhythmic risk among siblings of affected individuals despite its extremely low absolute frequency in the general population. The evidence of a measurable hereditary component within an otherwise sporadic, non-syndromic condition points to a genetic contribution driven by complex inheritance patterns
Two Studies Assessing Early Intervention Fit of Independent Living Services in Sweden
No full textPurpose: Young people transitioning from out-of-home care are a vulnerable group. This article reports two studies aiming to increase understanding of how to develop interventions for this group and focuses on preliminary intervention fit from the youth and social worker perspective. Methods: We conducted two small-scale studies. Social workers (Study I, n = 2; Study II, n = 9), and youth (Study I, n = 9; Study II, n = 13) completed self-report surveys containing both closed- and open-ended questions regarding the services with which they delivered and participated. Quantitative and qualitative analyses were used to analyze data. Results: Program content took longer to deliver than expected. Both studies indicate that the interventions were generally seen as fitting by youth and social workers. Social network and communication components were perceived as less fitting. Discussion: The results indicate that the interventions have the potential to achieve good fit and encourage further development and study
Mapping the distribution of neurotransmitters to resting-state functional connectivity in Parkinson's disease
No full textDopamine and serotonin are two major monoamine neurotransmitters associated with Parkinson's disease (PD), but their spatial distribution and relationship to underlying functional brain architecture are not fully understood. We assessed 30 patients with PD at baseline using structural MRI, resting-state functional MRI (rs-fMRI), 11C-PE2I and 11C-DASB PET, along with comprehensive clinical evaluations of motor and non-motor symptoms. Of these, 15 patients with PD who completed the same assessments after 19 months were included in the longitudinal analysis. rs-fMRI was used to assess functional connectivity, while 11C-PE2I and 11C-DASB PET were used to evaluate interregional homogeneity of dopamine and serotonin levels, referred to as PET covariance. Functional connectivity and PET covariance were estimated using a region-of-interest (ROI)-based approach with 138 ROIs from the Automated Anatomical Labelling 3 atlas, excluding cerebellar regions. These ROIs were further grouped into eight networks: visual, sensorimotor, attention, limbic, frontoparietal, default mode, subcortical and brainstem. At baseline, linear regression revealed that functional connectivity was positively associated with both 11C-PE2I PET covariance (β-values ranging from 0.575 to 0.790, P < 0.001) and 11C-DASB PET covariance (β-values ranging from 0.356 to 0.773, P < 0.001) across all networks. Longitudinally, we found positive correlations between baseline functional connectivity and both 11C-PE2I PET change covariance and 11C-DASB PET change covariance (β-values ranging from 0.166 to 0.576 and 0.312 to 0.671, respectively, P < 0.001) across all networks. These correlations remained significant after controlling for the Euclidean distance between ROIs, indicating that the association is independent of spatial proximity. For both tracers, absolute PET uptake across seed ROIs was positively associated with correspondent regression-derived functional connectivity-PET β-weights, which represent the relationship between PET uptake in target ROIs and their functional connectivity to the seed. This association between target functional connectivity and PET uptake was correlated with PD motor and non-motor severity across different brain regions in a manner that was dependent on the neurotransmitter system evaluated. Our findings suggest that in patients with PD, dopamine and serotonin levels covary among brain regions that are highly functionally connected. This implies that the spatial distribution of these neurotransmitters follows the organizational principles of the brain's functional connectomes, which are associated with features of the disease