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On properties and numerical computation of critical points of eigencurves of bivariate matrix pencils
Full text linkWe investigate critical points of eigencurves of bivariate matrix pencils . Points for which form algebraic curves in and we focus on points where . Such points are referred to as zero-group-velocity (ZGV) points, following terminology from engineering applications. We provide a general theory for the ZGV points and show that they form a subset (with equality in the generic case) of the 2D points , where ▫▫ is a multiple eigenvalue of the pencil ▫▫, or, equivalently, there exist nonzero ▫▫ and ▫▫ such that ▫▫, ▫▫, and ▫▫. We introduce three numerical methods for computing 2D and ZGV points. The first method calculates all 2D (ZGV) points from the eigenvalues of a related singular two-parameter eigenvalue problem. The second method employs a projected regular two-parameter eigenvalue problem to compute either all eigenvalues or only a subset of eigenvalues close to a given target. The third approach is a locally convergent Gauss–Newton-type method that computes a single 2D point from an inital approximation, the later can be provided for all 2D points via the method of fixed relative distance by Jarlebring, Kvaal, and Michiels. In our numerical examples we use these methods to compute 2D-eigenvalues, solve double eigenvalue problems, determine ZGV points of a parameter-dependent quadratic eigenvalue problem, evaluate the distance to instability of a stable matrix, and find critical points of eigencurves of a two-parameter Sturm–Liouville problem
Multi-modality approach to detect device-related thrombus after left atrial appendage occlusion
Full text linkBackground: There has been a growing interest in using left atrial appendage occlusion (LAAO) for stroke prevention in patients with atrial fibrillation (AF) who are ineligible for oral anticoagulation. However, device-related thrombus (DRT) may occur after LAAO implantation and poses significant diagnostic and treatment challenges. Case summary: We describe a case of a patient who suffered an intracranial pontine haemorrhage while on anticoagulation with rivaroxaban for permanent atrial fibrillation and successfully underwent implantation of the LAAO device. Early follow-up transoesophageal echocardiography (TOE) with 3D multi-plane reconstruction revealed a large echo-dense mass on the left atrial aspect of the device. Cardiac computed tomography angiography confirmed a thrombus adherent to the LAAO device. After deciding on the treatment strategy, complete thrombus resolution was achieved at the 6 months follow-up and the patient was free of any thromboembolic and bleeding events. Discussion: Although DRT is a rare complication following LAAO procedure, an accurate diagnosis is crucial for the specific treatment. Multi-modality imaging approach with TOE and cardiac computed tomographic angiography as complementary methods is helpful to detect complications after LAAO procedure in challenging cases
Routine 36-week scan
Full text linkObjectives: First, to report the incidence of non-cephalic presentation at a routine 36-week ultrasound scan, the uptake and success of external cephalic version (ECV) and the incidence of spontaneous rotation from non-cephalic to cephalic presentation. Second, to determine the maternal and pregnancy characteristics that provide a significant contribution to the prediction of non-cephalic presentation at the 36-week scan, successful ECV from non-cephalic to cephalic presentation and spontaneous rotation from non-cephalic to cephalic presentation. Methods: This was a retrospective analysis of prospectively collected data from 107 875 women with a singleton pregnancy who had undergone a routine ultrasound scan at 35 + 0 to 36 + 6 weeks\u27 gestation. Patients with breech or transverse/oblique presentation were divided into two groups: those scheduled for elective Cesarean section for a fetal or maternal indication other than abnormal presentation, and those that would potentially require ECV. The latter group was reassessed after 1-2 weeks and, if the abnormal presentation persisted, the parents were offered ECV or elective Cesarean section at 38-40 weeks\u27 gestation. Multivariable logistic regression analysis was carried out to determine which maternal and pregnancy characteristics provided a significant contribution in the prediction of non-cephalic presentation at the 36-week scan, successful ECV from non-cephalic to cephalic presentation and spontaneous rotation from non-cephalic to cephalic presentation. Results: At the 36-week scan, fetal presentation was cephalic in 101 664 (94.2%) pregnancies and either breech, transverse or oblique in 6211 (5.8%). In 0.3% of cases with cephalic presentation at the 36-week scan, there was subsequent spontaneous rotation to non-cephalic presentation, and in half of these, the diagnosis was made during labor or at birth. ECV was attempted in 1584/6211 (25.5%) pregnancies with non-cephalic presentation at the 36-week scan and was successful in only 44.1% of cases. In the remaining 74.5% of cases, ECV was not attempted because of any of the following reasons: ECV was declinedCesarean section was planned for a reason other than abnormal presentationECV was planned for the subsequent 1-2 weeks but, in the meantime, there was spontaneous rotation to cephalic presentationor there was spontaneous onset of labor or rupture of membranes before planned ECV. In 5513/6211 (88.8%) pregnancies with non-cephalic presentation at the 36-week scan, ECV was not attempted or was unsuccessful, and in 37.7% of these, there was subsequent spontaneous rotation to cephalic presentation. Among the 6211 pregnancies with non-cephalic presentation at the 36-week scan, the presentation at birth was cephalic in 43.8%in 74.8%, this was due to spontaneous rotation, and in 25.2%, it was due to successful ECV. Multivariable analysis demonstrated that the likelihood of non-cephalic presentation at the 36-week scan, that of successful ECV and that of spontaneous rotation from non-cephalic to cephalic presentation was affected by several maternal and pregnancy characteristics, but the predictive performance for these events was poor, with the area under the receiver-operating-characteristics curve ranging from 0.608 to 0.717 and the detection rate at a 10% false-positive rate ranging from 19.0% to 33.7%. Conclusions: Routine ultrasound examination at 35 + 0 to 36 + 6 weeks\u27 gestation could improve pregnancy outcome by substantially reducing the risk of unexpected abnormal presentation in labor. However, an additional ultrasound scan for fetal presentation should be considered in all women when they present in labor
Thrombus composition and the evolving role of tenecteplase in acute ischemic stroke
Full text linkAcute ischemic stroke (AIS) is a leading cause of disability and death worldwide, requiring rapid reperfusion to minimize damage. Current treatments, including intravenous thrombolysis (IVT) with alteplase (rt-PA) and mechanical thrombectomy (MT), face limitations such as thrombolysis resistance, dosing complexity, and reduced efficacy in large vessel occlusions (LVOs) or fibrin-rich clots. Tenecteplase (TNK), a bioengineered thrombolytic agent with superior pharmacokinetics, simplified administration, and higher fibrin specificity, offers promising advantages over rt-PA, including potential synergy with MT and efficacy against resistant thrombi. Direct oral anticoagulants (DOACs) further complicate AIS management, but evidence suggests that DOAC-treated patients may experience better thrombolysis outcomes due to distinct thrombus characteristics. Advances in imaging now enable precise visualization of vessel occlusion and treatment effects, opening opportunities to refine therapies. Combination approaches targeting fibrin thrombus components may enhance thrombolysis and improve outcomes in resistant cases. Future research should explore TNK’s role in intra-arterial (IA) applications, combination therapies, and its interaction with MT to optimize reperfusion strategies. TNK’s simplified use and promising efficacy position it as a potential breakthrough in AIS management, with the potential to improve functional recovery and reduce treatment complexity
Evaluating motor deficits in multiple sclerosis using jump and hop tests
Full text linkMultiple sclerosis (MS) is a chronic neurological disease that often leads to subtle motor impairments even in early stages. Traditional clinical assessments may fail to detect these early deficits. Jump and hop tasks, requiring complex neuromuscular coordination, have emerged as promising functional assessments in neurological populations. This review aims to synthesize current evidence on the use of jump- and hop-based assessments to evaluate motor performance in people with MS (pwMS). A systematic search of PubMed and Scopus was conducted in April 2025. Studies were included if they involved pwMS, used jump or hop tasks, and reported performance, kinetic, or kinematic outcomes. Nine studies met inclusion criteria. Countermovement jumps (CMJ) were most frequently used and consistently detected motor deficits in pwMS, including reduced flight time, jump height, and power output. Single-leg CMJ tests identified asymmetries correlated with disability scores. Bipedal hops revealed impaired coordination and anticipatory control. One study assessed motor fatigability through repetitive jumping, while another evaluated the patient experience of sensor-based jump testing. Jump and hop assessments provide potentially sensitive, non-invasive tools for detecting early motor impairments in MS. They offer potential for improving clinical monitoring and guiding individualized rehabilitation strategies
Climate-driven habitat shifts in brown algal forests: insights from the Adriatic Sea
Full text linkBrown algal forests (Cystoseira sensu lato) are key habitat-forming components of temperate rocky coasts but have experienced widespread decline across the Mediterranean Sea. This study investigates the current distribution and potential future shifts in brown algal forests across the Adriatic Sea under ongoing climate change. We combined non-destructive field-based mapping along the Slovenian coastline with remote-sensing products and spatial environmental predictors to model basin-wide habitat suitability. A multiscale geographically weighted regression (MGWR) framework was applied to account for spatial non-stationarity and to explicitly capture the fact that environmental drivers of habitat suitability operate at different spatial scales—an assumption that global models such as GAM or standard GWR cannot adequately address. Habitat suitability maps were generated for present-day conditions and projected under mid- and late-century climate scenarios. The results reveal pronounced latitudinal gradients, identify areas of ongoing canopy decline in the northern Adriatic, and highlight parts of the southern Adriatic as potential climate refugia. Overall, the study demonstrates a likely north–south contraction of suitable habitat for brown algal forests and underscores the value of multiscale spatial modelling for informing marine spatial planning, conservation prioritization, and climate- adaptive restoration under European policy frameworks
Detecting bark beetle-induced changes in coniferous alpine forests using Sentinel-2 time series and in-situ felling data
Full text linkMapping forest areas affected by bark beetle infestation using remote sensing imagery is crucial for effective hazard management and risk assessment. This study evaluates the potential of Sentinel-2 satellite image time series (SITS) in combination with in-situ felling data to detect bark beetle infestation in coniferous forests in Pokljuka, Slovenia. The analysis uses the CuSum method, all Sentinel-2 spectral bands and key spectral indices such as NDVI and NBSI to identify changes and areas of forest loss in the period 2017–2021. The resulting geospatial dataset, which integrates these remote sensing results with field data, serves as a basis for further analyses using advanced machine and deep learning methods and various remote sensing data such as hyperspectral datasets. In addition, we found that the most useful bands for detecting the loss of alpine coniferous forests are SWIR (B11, B12), Red (B04) and Red-Edge (B05) as well as the two spectral in dices used, NDVI and NBSI.Kartiranje gozdnih območij, ki jih je napadel lubadar, s pomočjo posnetkov daljinskega zaznavanja je ključnega pomena za učinkovito obvladovanje nevarnosti in oceno tveganja. Ta študija ocenjuje možnosti časovnih serij satelitskih posnetkov Sentinel-2 (SITS) v kombinaciji s podatki o sečnji na kraju samem za odkrivanje napada lubadarja v iglastih gozdovih na Pokljuki v Sloveniji. Analiza uporablja metodo CuSum, vse spektralne pasove Sentinel-2 in ključne spektralne indekse, kot sta NDVI in NBSI, za ugotavljanje sprememb in območij izgube gozdov v obdobju 2017-2021. Nastali geoprostorski podatkovni niz, ki združuje te rezultate daljinskega zaznavanja s terenskimi podatki, služi kot podlaga za nadaljnje analize z uporabo naprednih metod strojnega in globokega učenja ter različnih podatkov daljinskega zaznavanja, na primer hiperspektralnih podatkovnih nizov. Poleg tega smo ugotovili, da so najbolj uporabni spektralni kanali za zaznavanje izgube alpskih iglastih gozdov kratkovalovna infrardeča kanala (B11, B12), rdeči kanal (B04) in kanal rdečega roba (B05) ter uporabljena spektralna indeksa, NDVI in NBSI
Effective cryopreservation of post mortem-collected roe deer gametes by evaluation of post-thaw oocyte and sperm characteristics and in vitro fertilization
Full text linkThe aim was to evaluate the effectiveness of semen cryopreservation and oocyte vitrification in roe deer as a potential method of gamete preservation for endangered deer species. Sperm were isolated from the cauda epididymis of fourteen bucks (n = 14). The motility measure (CASA) and morphology of fresh semen (FS) and frozen–thawed semen (TS) were compared. A hyaluronic binding assay was used to distinguish between mature FS spermatozoa expressing hyaluronan receptors and immature FS lacking these receptors, and the mitochondrial membrane potential (MMP) in TS was determined (flow cytometry). A Sperm–Hyaluronan Binding Assay (HBA) showed a viability rate of 61.9% in FS and 78.2% in TS. Oocytes received from eight does (n = 8) underwent a viability test and vitrification, and fresh oocytes from the other eight does (n = 8) were fertilized with TS and embryos were cultured until the blastocyst stage. The number of isolated oocytes, cumulus–oocyte complexes (COCs), cleaved embryos, and expanded blastocysts was evaluated. Higher percentages of morphological factors (acrosome, head, midpiece, and tail shape) were observed in FS compared to TS, whereas the motility and progressive movement were greater in TS (p ≤ 0.001). The viability was 50.5% and MMP was 40.6% in TS. A total of 311 oocytes were collected and from 150 COCs and 125 blastocysts developed. The viability of thawed oocytes after vitrification was 81%. The viability of vitrified oocytes and cryopreserved sperm confirmed the effectiveness of freezing protocols and highlights the potential for their implementation in other deer species
