Scientific publications of the Saarland University
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Anatomical Lens Position Predictability for a Capsulotomy-Fixated Intraocular Lens in Femtosecond Laser-Assisted Cataract Surgery
Get PDFObjectives: To assess the anatomical lens position (ALP) predictability for a capsulotomy fixated intraocular lens (IOL; FEMTIS FB-313, Teleon Surgical B.V) versus an intracap sular IOL (TECNIS 1-Piece, ZCB00V, Johnson & Johnson) implanted for age-related
cataracts. Methods: Pre- and 3-month postoperative measurements from optical biom etry and swept-source anterior segment OCT were analyzed. The lens position (i.e.,
postoperatively, ALP) was defined as the distance between the corneal endothelium
and the lens equator. Multivariate linear mixed-effects models assessed the influence
of preoperative biometric parameters on ALP, prediction error (PE), and absolute PE
(AbsPE). Results: A total of 45 FEMTIS eyes from 32 patients and 26 TECNIS eyes
from 18 patients were included. Postoperatively, the anterior chamber depth (ACD)
increased by 1.10 mm in FEMTIS eyes and 1.66 mm in TECNIS eyes, while the lens
position decreased by 0.59 mm and 0.34 mm, respectively. ACD and lens thickness
(LT) were the strongest ALP predictors (ACD: β = +0.70, p < 0.0001; LT: β = +0.37,
p < 0.0001). Separate multivariate models demonstrated strong predictive performance,
with the FEMTIS achieving R2 = 0.92 and the TECNIS IOL performing even better with
R
2 = 0.97. In the FEMTIS group, LT influenced the PE (p = 0.006) and ACD the AbsPE
(p = 0.005). In the TECNIS group, ACD influenced the PE (p < 0.0001), while AbsPE was
not significantly affected by biometric parameters or formulas. Conclusions: ALP can be
reliably predicted from standard biometric data, although less accurately for the FEMTIS
IOL. Its anterior capsulotomy fixation likely compromises refractive accuracy with formulas
inherently designed and optimized for in-the-bag IOLs, emphasizing the need for fixation specific formula adjustments and dedicated optimization in capsulotomy-fixated IOLs
Quantum theory of the diamond maser: Stimulated and superradiant emission
Get PDFWe present a quantum theory of diamond masers operating at any temperature using a cavity quantum
electrodynamical framework. Special attention is paid to the recently demonstrated room-temperature solid-state
masers based on nitrogen-vacancy (NV) defect centers in diamond, but the model can easily be modified for
other photoexcited chromophores such as pentacene-doped paraterphenyl, vacancies in silicon-carbide or boron
nitride. We show that the eight energy levels involved in the optically pumped NV center polarization process
can be mapped to a simple pumped two-level-system. We then derive simple analytical expressions for the
optical pump threshold condition for masing as well as the steady-state microwave output power which can be
used to design and predict maser performance. Finally, we investigate second-order correlations and find that
typical diamond masers operate in an intermediate regime between the good and bad cavity limits where photon
emission is driven by both stimulated and superradiant processes
Understanding and supporting same-side interaction with wrist-worn devices
No full textLatest advancements in mobile and wearable computing, especially due to miniaturization of technical components, bring up more and more powerful wrist-worn devices with smart features such as touchscreens, advanced sensors or novel interaction possibilities. Despite their technical sophistication, the inherently small screen size generates new challenges, both, for input and output. The mobile nature of the devices results in varying application contexts, while the position on the wrist complicates perception of information as well as interaction with the device - especially with respect to touch input that always requires the involvement of both hands. In this thesis, we investigate same-side interactions only involving the hand that is wearing the device to overcome the aforementioned problems. We contribute to the field of wearable computing and human-computer interaction by investigating the following three directions: Exploration of state-of-the-art interactions concepts, investigation of novel interaction designs, and comparison of opposite- and same-side interaction methods. Based on online questionnaires and user studies, insights into the underlying foundations are provided and guidelines for improving the interaction design of smart wrist-worn devices are offered. We further contribute to the dissemination of applications making use of data from wearable devices by providing advanced gesture detection and classification methods. Additionally, a tool is provided to help evaluating the perception of user interfaces for wrist-worn devices.Die jüngsten Entwicklungen im Bereich mobiler und am Körper getragener Geräte, insbesondere die Miniaturisierung der technischen Komponenten, führen zu immer leistungsfähigeren Geräten, die am Handgelenk getragen werden können und über intelligente Funktionen wie Touchscreens, fortschrittliche Sensorik oder neuartige Interaktionsmöglichkeiten verfügen. Trotz ihrer technischen Ausgereiftheit bringen die mit der Gerätegröße einhergehenden kleinen Bildschirme neue Herausforderungen mit sich, sowohl für die Eingabe- als auch die Ausgabeseite. Der mobile Charakter der Geräte führt zu häufig wechselnden und potentiell sehr unterschiedlichen Anwendungskontexten. Die fixe Position am Handgelenk erschwert zusätzlich die Wahrnehmung von Informationen sowie die Interaktion mit dem Gerät - insbesondere im Hinblick auf Eingabe mittels Finger, die immer die Beteiligung beider Hände erfordert. In dieser Thesis untersuchen wir Interaktionen, die nur die Hand einbeziehen, an deren Handgelenk das Gerät getragen wird, um die oben genannten Herausforderungen zu überwinden. Wir leisten dabei Beiträge zur Weiterentwicklung der Gebiete Wearable Computing und Mensch-Computer-Interaktion, indem wir in den folgenden drei Bereichen forschen: Exploration moderner Interaktionskonzepte, Untersuchung neuartiger Interaktionsdesigns sowie Vergleich von beid- und einhändigen Interaktionsmethoden. Anhand von Onlineumfragen und Nutzerstudien liefern wir Erkenntnisse, die zu einem besseren Verständnis der unterliegenden Konzepte führen und formulieren Richtlinien zur Verbesserung des Interaktionsdesigns von smarten, am Handgelenk getragenen Geräten. Darüber hinaus leisten wir einen Beitrag zur einfacheren Entwicklung und Verbreitung von Anwendungen, die Sensordaten von tragbaren Geräten nutzen, indem wir verbesserte Methoden zur Gestenerkennung und -klassifizierung bereitstellen. Außerdem stellen wir ein Tool zur Verfügung, das bei der Bewertung der Wahrnehmung von Benutzerschnittstellen für am Handgelenk getragene Geräte unterstützt
Exploring the in silico adaptation of the Nephroblastoma Oncosimulator to MRI scans, treatment data, and histological profiles of patients from different risk groups
No full textIntroduction: Nephroblastoma or Wilms’ tumor is the most prevalent type of renal tumor in pediatric oncology. Although the overall survival rate for this condition is excellent today (∼90%), there have been no significant improvements over the past two decades. In silico models aim to simulate tumor progression and treatment responses over time; they hold immense potential for enhancing the predictive accuracy and optimizing treatment protocols as they are inspired by the digital twin paradigm.
Methods: The present study uses T2-weighted magnetic resonance images, chemotherapy treatment plans, and post-surgical histological profiles from three patients enrolled in the SIOP 2001/GPOH clinical trial, where each patient represents a distinct clinically assessed risk group. We investigated the clinical adaptation of the Nephroblastoma Oncosimulator to the datasets from these patients with the goal of deriving appropriate value distributions of the model input parameters that enable accurate prediction of tumor volume reduction in response to preoperative chemotherapy.
Results: Our primary focus was on the total cell kill ratio as a parameter reflecting treatment effectiveness. We derived the distribution of this parameter for one patient from each risk group: low (Mdn = 0.875, IQR [0.750, 0.875], n = 178), intermediate (Mdn = 0.875, IQR [0.750, 0.875], n = 175), and high (Mdn = 0.485, IQR [0.438, 0.532], n = 103). Statistically significant differences were observed between the high-risk group and both the low- and intermediate-risk groups (p < 0.001).
Discussion: The present work establishes a foundation for further studies using available retrospective datasets and additional patients per risk group. These efforts are expected to help validate the findings, advance model development, and extend this mechanistic multiscale discretized cancer model. However, clinical validation is ultimately required to assess the potential uses of the model in clinical decision-support systems
Validation of a Newly Developed Assessment Tool for Point-of-Care Ultrasound of the Thorax in Healthy Volunteers (VALPOCUS)
Get PDFObjectives: Point-of-care ultrasound (POCUS) has become an integral part of emergency, in tensive care, and perioperative medicine. However, the training and subsequent evaluation
of POCUS users are still not standardized. The aim of the study was to develop and validate
an assessment tool for POCUS users. Methods: After reviewing the existing literature and
a multi-stage expert survey (Delphi method), consensus on twelve items for the assessment
tool was reached. To validate the assessment tool, a group of volunteer doctors and medical
students performed a POCUS examination using simple linear probe and more complex
sector probe techniques. The examination was evaluated by two independent assessors
using the created assessment tool. Then, four experts evaluated anonymized recordings
of the examinations. We tested the reliability and validity, including internal consistency.
Results: A total of 70 examinations were included. Of these, 19 examinations were carried
out by physicians and 51 by medical students. A high inter-rater reliability (Cohen’s kappa
0.78 (linear weighted; SEM 0.37; p < 0.001) and Krippendorff’s alpha 0.895) was shown
for the evaluation tool. To improve discriminative power and strengthen reliability, the
assessment tool was modified using Cronbach’s alpha. Modification resulted in the removal
of three items (patient positioning, ultrasound mode selection, and probe selection) from
the tool. The mean values of instrument and expert ratings were now 2.62% apart (46.90%
instrument vs. 44.29% expert). Pearson’s correlation coefficient between tool and expert
ratings showed moderate to high validity (r = 0.69; p < 0.001). Conclusions: The new
assessment tool is highly reliable and a valid tool for assessing POCUS skills. It holds
strong potential for integration into medical education and training to objectify ultrasound
skills. Further studies are required to investigate discriminatory power and transferability
to other POCUS algorithms
Virtual Energy Replication Framework for Predicting Residential PV Power, Heat Pump Load, and Thermal Comfort Using Weather Forecast Data
Get PDFIt is essential to balance energy supply and demand in residential buildings through accurate forecasting of energy use due to varying daily and seasonal residential building loads. This study demonstrates a data-driven Virtual Energy Replication Framework (VERF) to predict the behavior of residential buildings using weather forecast data. The framework integrates supervised machine learning models and time-ahead weather parameters to estimate photovoltaic (PV) power production, heat pump energy consumption, and indoor thermal comfort. The accuracy of prediction models is validated using TRNSYS simulations of a typical household in Saarbrucken, Germany, a temperate oceanic climate region. The XGBoost model exhibits the highest reliability, achieving a root mean square error (RMSE) of 0.003 kW for PV power generation and 0.025 kW for heat pump energy use, with R2 scores of 0.94 and 0.87, respectively. XGBoost and random forest regression models perform well in predicting PV generation and HP electricity load, with mean prediction errors of 5.27–6% and 0–7.7%, respectively. In addition, the thermal comfort index (PPD) is predicted with an RMSE of 1.84 kW and an R2 score of 0.80 using the XGBoost model. The mean prediction error remains between 2.4% (XGBoost regression) and −11.5% (lasso regression) throughout the forecasted data. Because the framework requires no real-time instrumentation or detailed energy modelling, it is scalable and adaptable for smart building energy systems, and has particular value for Building-Integrated Photovoltaics (BIPV) demonstration projects on account of its predictive load-matching capabilities. The research findings justify the applicability of VERF for efficient and sustainable energy management using weather-informed prediction models in residential buildings
On the limits of LLM surprisal as a functional explanation of the N400 and P600
No full textExpectations about upcoming words play a central role in language comprehension, with expected words being processed more easily than less expected ones. Surprisal theory formalizes this relationship by positing that cognitive effort is proportional to a word’s negative log-probability in context, as determined by distributional, linguistic, and world knowledge constraints. The emergence of large language models (LLMs) demonstrating the capacity to compute richly contextualized surprisal estimates, has motivated their consideration as models of comprehension. We assess here the relationship of LLM surprisal with two key neural correlates of comprehension – the N400 and the P600 – which differ in sensitivity to semantic association and contextual expectancy. While prior work has focused on the N400, we propose that the P600 may offer a better index of surprisal, as it is unaffected by association while still patterning continuously with expectancy. Using regression-based ERPs (rERPs), we examine data from three German factorial studies to evaluate the extent to which LLM surprisal can account for ERP differences. Our results show that LLM surprisal captures neither component consistently. We find that it is contaminated by simple association, particularly in smaller LLMs. As a result, LLM surprisal can partially account for association-driven N400 effects, but not for the full attenuation of N400 effects. Correspondingly, this property of LLMs compromises their ability to model the P600, which is sensitive to expectancy but not to association
A comprehensive review and evaluation of species richness estimation
Get PDFMotivation: The statistical problem of estimating the total number of distinct species in a population (or distinct elements in a multiset),
given only a small sample, occurs in various areas, ranging from the unseen species problem in ecology to estimating the diversity of
immune repertoires. Accurately estimating the true richness from very small samples is challenging, in particular for highly diverse
populations with many rare species. Depending on the application, different estimation strategies have been proposed that incorporate
explicit or implicit assumptions about either the species distribution or about the sampling process. These methods are scattered across
the literature, and an extensive overview of their assumptions, methodology, and performance is currently lacking.
Results: We comprehensively review and evaluate a variety of existing methods on real and simulated data with different compositions
of rare and abundant species. Our evaluation shows that, depending on species composition, different methods provide the most
accurate richness estimates. Simple methods based on the observed number of singletons yield accurate asymptotic lower bounds for
several of the tested simulated species compositions, but tend to underestimate the true richness for heterogeneous populations and
small samples containing 1% to 5% of the population. When the population size is known, upsampling (extrapolating) estimators such
as PreSeq and RichnEst yield accurate estimates of the total species richness in a sample that is up to 10 times larger than the observed
sample.
Availability: Source code for data simulation and richness estimation is available at https://gitlab.com/rahmannlab/speciesrichness
CK2 regulates somatostatin expression in pancreatic delta cells
Get PDFPancreatic and duodenal homeobox protein (PDX)1 is a major transcription factor for the regula tion of insulin, glucagon and somatostatin (SST) expression. PDX1 is phosphorylated by CK2 and
inhibition of this kinase results in an increased insulin and decreased glucagon secretion.
Therefore, we speculated in this study that CK2 also affects SST expression. To test this, we
analyzed the effects of the two CK2 inhibitors CX-4945 and SGC as well as of PDX1 overexpression
on SST expression and secretion in RIN14B cells by qRT-PCR, luciferase assays, Western blot and
ELISA. SST expression and secretion were additionally assessed in isolated murine and human islets
exposed to the CK2 inhibitors. Moreover, we determined the expression and secretion of the
pancreatic endocrine hormones in CX-4945-treated mice. We found a suppressed SST expression in
RIN14B cells due to a methylated SST promoter, which could be abolished by DNA demethylation.
Under these conditions, we showed that CK2 inhibition increases SST gene expression and
secretion. Additional experiments with overexpression of a CK2-phosphorylation mutant of PDX1
verified that SST expression is regulated by CK2. The exposure of isolated murine and human islets
to CX-4945 or SGC as well as the treatment of mice with CX-4945 revealed that CK2 also regulates
SST expression under physiological conditions. Taken together, these findings not only demon strate that CK2 controls SST expression in pancreatic δ-cells but also emphasize the crucial role of
this kinase in regulating the main hormones of the endocrine pancreas
Der Einfluss eines Artischockenblätterextraktes zur Therapie der metabolischen Dysfunktion-assoziierten steatotischen Lebererkrankung
Get PDFA randomized, placebo-controlled, single blind, monocentric trial to investigate the influence of an artichoke leaf extract for the treatment of metabolic dysfunction-associated steatotic liver disease
Background:
The increasing prevalence of obesity and its related comorbidities, including metabolic dysfunction associated steatotic liver disease (MASLD) and metabolic dysfunction associated steatohepatitis (MASH), poses significant challenges to healthcare systems worldwide. MASLD and MASH are particularly prevalent among bariatric surgery candidates, necessitating interventions to reduce liver steatosis preoperatively. The SteatoChoke-study investigates the efficacy of artichoke leaf extract (ALE) in reducing liver steatosis in pre-bariatric surgery patients.
Methods:
In this prospective, randomized, placebo-controlled, single-blind study conducted at a bariatric competence center between 2022 and 2023, 40 patients scheduled for bariatric surgery were randomized to receive either ALE or a placebo for six weeks, first for three weeks followed by a specialized liver diet for another three weeks. Degree of liver steatosis was assessed at three measurement times. The primary outcome was shown in the CAP value (controlled attenuation parameter), which determines the extend of liver steatosis using transient elastography (FibroScan®) as well as the change in liver size measured by ultrasound. Secondary outcomes included changes in serum laboratory parameters and body composition through bioelectrical impedance analysis (BIA).
Results:
Artichoke leaf extract statistically significantly reduced CAP values and liver size compared to the placebo group (337.5 ± 6.04 dB/m vs. 364.31 ± 4.84 dB/m, p = .003 and 117.61 ± 2.55 mm vs. 129.67 ± 2.99 mm, p = .005), indicating a reduction in liver steatosis. Notably, these effects were observed already after three weeks of ALE intake, without additional dietary measures. Significant improvements were also observed in both, LDL and total cholesterol levels (125.81 ± 4.07 mg/dl vs. 112.47 ± 6.35 mg/dl, p = .018), along with markers of inflammation (CRP, IL-6: p = .019 and p = .046, respectively) in the artichoke group. Serum transaminase levels were notably increased in the artichoke group (ALAT: 50.16 ± 3.53 U/l vs. 41.33 ± 5.54 U/l; ASAT: 34.84 ± 2.29 U/l vs. 28.33 ± 2.10 U/l, p < .05). Additionally, bioelectrical impedance analysis data indicated favorable shifts in body composition among the patients of the artichoke group.
Conclusion:
Artichoke leaf extract significantly reduced liver steatosis and improved serum biochemical parameters and body composition in pre-bariatric surgery patients. These findings suggest that ALE could be a valuable component of preoperative care in patients with obesity and MASLD/MASH, potentially enhancing surgical outcomes and patient safety. Further research is necessary to confirm these results and establish ALE as a standard preoperative intervention.Kurzfassung
Der Einfluss eines Artischockenblätterextraktes zur Therapie der metabolischen Dysfunktion-assoziierten steatotischen Lebererkrankung
Hintergrund:
Die zunehmende Prävalenz der Adipositas und die damit einhergehenden Begleiterkrankungen, einschließlich der metabolischen Dysfunktion-assoziierten steatotischen Lebererkrankung (MASLD) und metabolischen Dysfunktion-assoziierten Steatohepatitis (MASH), stellen die Gesundheitssysteme weltweit vor erhebliche Herausforderungen. Beide Erkrankungen sind bei Patienten mit Adipositas besonders häufig zu beobachten. Optionen zur Reduzierung der Lebersteatose sind wünschenswert. Die SteatoChoke-Studie untersuchte die Wirksamkeit eines Artischockenblätterextraktes (ALE) zur Reduktion des Steatosegrades bei Patienten vor einer bariatrisch-metabolischen Operation.
Patienten und Methoden:
In dieser prospektiven, randomisierten, Placebo-kontrollierten, einfachblinden Studie, die zwischen 2022 und 2023 an einem bariatrischen Kompetenzzentrum durchgeführt wurde, wurden 40 Patienten, die für eine bariatrische Operation vorgesehen waren, randomisiert und erhielten präoperativ für sechs Wochen entweder Artischockenblätterextrakt oder ein Placebo. Nach drei Wochen folgte zusätzlich eine spezielle Leberdiät für weitere drei Wochen. Der Grad der Lebersteatose wurde an drei Messzeitpunkten beurteilt. Als primäre Endpunkte wurden der CAP-Wert (Controlled Attenuation Parameter), der mithilfe der transienten Elastographie (FibroScan®) das Ausmaß der Leberverfettung bestimmt sowie die Veränderung der Lebergröße, gemessen mittels Sonographie, festgelegt. Als sekundäre Endpunkte wurden Veränderungen der Serumlaborparameter und der Körperzusammensetzung, ermittelt durch die Bioelektrische Impedanzanalyse, erfasst.
Ergebnisse:
Artischockenblätterextrakt reduzierte statistisch signifikant die CAP-Werte und die Lebergröße im Vergleich zum Placebo (337.5 ± 6.04 dB/m vs. 364.31 ± 4.84 dB/m, p = .003 und 117.61 ± 2.55 mm vs. 129.67 ± 2.99 mm, p = .005), was auf eine Verringerung der Lebersteatose hinweist. Diese Effekte wurden bereits nach dreiwöchiger ALE-Einnahme ohne zusätzliche diätetische Maßnahmen beobachtet. Signifikante Verbesserungen in der ALE-Gruppe wurden sowohl bei den LDL- als auch bei den Gesamtcholesterin-Spiegeln im Serum (125.81 ± 4.07 mg/dl vs. 112.47 ± 6.35 mg/dl, p = .018) zusammen mit Entzündungsmarkern (CRP, IL-6: p = .019 und p = .046) beobachtet. Die
Kurzfassung
II
Serumtransaminasespiegel in der ALE-Gruppe waren signifikant erhöht (ALAT: 50.16 ± 3.53 U/l vs. 41.33 ± 5.54 U/l; ASAT: 34.84 ± 2.29 U/l vs. 28.33 ± 2.10 U/l, p < .05). Darüber hinaus zeigten Daten der Bioelektrischen Impedanzanalyse (BIA) günstige Veränderungen der Körperzusammensetzung bei den mit dem Artischockenblätterextrakt behandelten Patienten.
Zusammenfassung:
Artischockenblätterextrakt reduzierte signifikant die Lebersteatose, senkte den Cholesterinspiegel und bewirkte eine günstige Beeinflussung der Körperzusammensetzung bei Patienten vor einer bariatrischen Operation. Artischockenblätterextrakt könnte ein wertvoller Bestandteil der präoperativen Versorgung bei adipösen Patienten mit MASLD/MASH sein und möglicherweise die chirurgischen Ergebnisse und die Patientensicherheit verbessern. Weitere Untersuchungen sind erforderlich, um diese Ergebnisse zu bestätigen und ALE als standardmäßige präoperative Intervention zu etablieren