Cohesive mixed-mode damage model applied to the simulation of the mechanical behaviour of a repaired sandwich beam

The behaviour of a repaired sandwich beam loaded under four point bending is simulated using theABAQUS® software. Both overlap and scarf repair, suitable for sandwich structures, were simulatedconsidering two dimensional nonlinear material and geometrical analysis. Special developed interfacefinite elements including a trapezoidal cohesive mixed-mode damage model appropriate for ductileadhesives were used in order to simulate the adhesive layer. The proposed model is intended to replacethe continuum finite elements traditionally used to simulate the adhesive layer, thus reducing thecomputational effort necessary to obtain results. Double Cantilever Beam (DCB) and End NotchedFlexure (ENF) tests were used to obtain the cohesive laws of the adhesive in pure modes I and II,respectively. The fracture energies (JIc and JIIc) are obtained using a new data reduction scheme based oncrack equivalent concept allowing overcoming crack monitoring difficulties during propagation in thesefracture characterization tests. The remaining cohesive parameters (1,I, 1,II, 2,I, 2,II)are obtained usingan inverse method, which is based on the fitting of the numerical and experimental P- curves by a finetuning process. This procedure allows fixing the referred cohesive parameters to be used in the stressanalyses and strength predictions of repaired sandwiches. The numerical model allowed the simulation ofdamage initiation and growth. Geometric changes, such as patch overlap length and scarf angle wereconsidered in the analysis in order to assess their influence on the repair efficiency. Conclusions weredrawn about design guidelines of sandwich composite material repair

Buckling strength of adhesively-bonded single and double-strap repairs on carbon-epoxy structures

This work reports on an experimental and finite element method (FEM) parametric study of adhesively-bonded single and double-strap repairs on carbon-epoxy structures under buckling unrestrained compression. The influence of the overlap length and patch thickness was evaluated. This loading gains a particular significance from the additional characteristic mechanisms of structures under compression, such as fibres microbuckling, for buckling restrained structures, or global buckling of the assembly, if no transverse restriction exists. The FEM analysis is based on the use of cohesive elements including mixed-mode criteria to simulate a cohesive fracture of the adhesive layer. Trapezoidal laws in pure modes I and II were used to account for the ductility of most structural adhesives. These laws were estimated for the adhesive used from double cantilever beam (DCB) and end-notched flexure (ENF) tests, respectively, using an inverse technique. The pure mode III cohesive law was equalled to the pure mode II one. Compression failure in the laminates was predicted using a stress-based criterion. The accurate FEM predictions open a good prospect for the reduction of the extensive experimentation in the design of carbon-epoxy repairs. Design principles were also established for these repairs under buckling

Neonatal seizures—diagnostic options and treatment recommendations

Seizures in neonates should prompt rapid evaluation to verify the diagnosis, determine etiology, and initiate appropriate treatment. Neonatal seizure diagnosis requires EEG confirmation and clinical observation alone is insufficient. Although most neonatal seizures are related to acute brain injury, some neonates present early-onset structural or metabolic/genetic epilepsy. Video-EEG monitoring, the gold standard for neonatal seizure detection and quantification, is resource-intensive and often unavailable, with amplitude-integrated EEG offering a reasonable alternative in guiding treatment. Whereas new-generation antiseizure medication (ASM), such as levetiracetam, appear promising, particularly in terms of tolerability, older-generation ASM, such as phenobarbital and phenytoin, are yet to be replaced. Acute treatment should aim at stopping both electroclinical and electrographic-only seizures. In neonates with acute provoked seizures, ASM should be discontinued without tapering after 72 h of seizure freedom and before hospital discharge

Point-of-care EEG in the pediatric emergency department: a systematic review

Central nervous system (CNS) disorders, including seizures, status epilepticus (SE), and altered mental status, constitute a significant proportion of cases presenting in the pediatric emergency department. EEG is essential for diagnosing nonconvulsive SE, but standard EEG is often unavailable due to resource constraints. Point-of-care EEG (pocEEG) has emerged as a viable alternative, offering rapid bedside assessment. This systematic review synthesizes existing data on the use of pocEEG in pediatric emergencies and highlights research gaps. A comprehensive search of PubMed, CINAHL, and EMBASE identified six studies on pediatric populations using simplified EEG montages, with cohort sizes ranging from 20 to 242 patients. The findings indicate that pocEEG is feasible in acute pediatric care, effectively aiding in the detection of nonconvulsive SE and other critical neurological conditions. The studies varied in electrode placement strategies, ranging from neonatal to subhairline montages. Conclusion: Despite some implementation challenges, pocEEG has shown sufficient accuracy for clinical use. Further research should focus on optimizing EEG montages, refining interpretation, and assessing its impact on patient outcomes. This review underscores the potential of pocEEG to address critical care needs in pediatric emergency departments and calls for larger, standardized studies. What is Known: •  Central nervous system (CNS) disorders, such as seizures and altered mental status, are common and critical conditions encountered in pediatric emergency resuscitation bays.•  EEG is essential for diagnosing nonconvulsive status epilepticus, but standard EEG is often unavailable in emergency departments due to logistical challenges, limited resources, and the need for specialized interpretation. What is New: •  Reduced-lead, point-of-care EEG (pocEEG) is a feasible alternative for real-time bedside CNS monitoring in pediatric emergency settings, aiding in the diagnosis of nonconvulsive status epilepticus and guiding the management of convulsive status epilepticus.• This systematic review highlights the feasibility and clinical potential of pocEEG in pediatric emergency departments and identifies key areas for further research, including the development of standardized pocEEG protocols and the integration of automated EEG analysis

Ketogene Ernährungstherapien: mehr als nur Lifestyle-Diät

Ketogene Ernährungsformen werden heutzutage gerne eingesetzt zum Abnehmen oder für den Muskelaufbau. Im medizinischen Bereich stellen sie jedoch eine evidenzbasierte, etablierte Behandlungsoption bei pädiatrischen Epilepsien und ausgewählten Stoffwechselerkrankungen dar

Epilepsy Phenotypes of Vitamin B6-Dependent Diseases: An Updated Systematic Review

Background: Vitamin B6-dependent epilepsies include treatable diseases responding to pyridoxine or pyridoxal-5Iphosphate (ALDH7A1 deficiency, PNPO deficiency, PLP binding protein deficiency, hyperprolinemia type II and hypophosphatasia and glycosylphosphatidylinositol anchor synthesis defects). Patients and methods: We conducted a systematic review of published pediatric cases with a confirmed molecular genetic diagnosis of vitamin B6-dependent epilepsy according to PRISMA guidelines. Data on demographic features, seizure semiology, EEG patterns, neuroimaging, treatment, and developmental outcomes were collected. Results: 497 published patients fulfilled the inclusion criteria. Seizure onset manifested at 59.8 ± 291.6 days (67.8% of cases in the first month of life). Clonic, tonic-clonic, and myoclonic seizures accounted for two-thirds of the cases, while epileptic spasms were observed in 7.6%. Burst-suppression/suppression-burst represented the most frequently reported specific EEG pattern (14.4%), mainly in PLPB, ALDH7A1, and PNPO deficiency. Pyridoxine was administered to 312 patients (18.5% intravenously, 76.9% orally, 4.6% not specified), and 180 also received antiseizure medications. Pyridoxine dosage ranged between 1 and 55 mg/kg/die. Complete seizure freedom was achieved in 160 patients, while a significant seizure reduction occurred in 38. PLP, lysine-restricted diet, and arginine supplementation were used in a small proportion of patients with variable efficacy. Global developmental delay was established in 30.5% of a few patients in whom neurocognitive tests were performed. Conclusions: Despite the wide variability, the most frequent hallmarks of the epilepsy phenotype in patients with vitamin B6-dependent seizures include generalized or focal motor seizure semiology and a burst suppression/suppression burst pattern in EEG

A Spiking Neural Network (SNN) for detecting High Frequency Oscillations (HFOs) in the intraoperative ECoG

To achieve seizure freedom, epilepsy surgery requires the complete resection of the epileptogenic brain tissue. In intraoperative ECoG recordings, high frequency oscillations (HFOs) generated by epileptogenic tissue can be used to tailor the resection margin. However, automatic detection of HFOs in real-time remains an open challenge. Here we present a spiking neural network (SNN) for automatic HFO detection that is optimally suited for neuromorphic hardware implementation. We trained the SNN to detect HFO signals measured from intraoperative ECoG on-line, using an independently labeled dataset. We targeted the detection of HFOs in the fast ripple frequency range (250-500 Hz) and compared the network results with the labeled HFO data. We endowed the SNN with a novel artifact rejection mechanism to suppress sharp transients and demonstrate its effectiveness on the ECoG dataset. The HFO rates (median 6.6 HFO/min in pre-resection recordings) detected by this SNN are comparable to those published in the dataset (58 min, 16 recordings). The postsurgical seizure outcome was "predicted" with 100% accuracy for all 8 patients. These results provide a further step towards the construction of a real-time portable battery-operated HFO detection system that can be used during epilepsy surgery to guide the resection of the epileptogenic zone.Comment: 11 pages, 3 figures, 2 tables. The results of this publication were obtained by simulating our hardware platform, built for online processing of biological signals. This hardware combines neural recording headstages with a multi-core neuromorphic processor arxiv.org/abs/2009.1124

Epilepsy Phenotypes of Vitamin B6-Dependent Diseases: An Updated Systematic Review

BACKGROUND: Vitamin B6-dependent epilepsies include treatable diseases responding to pyridoxine or pyridoxal-5Iphosphate (ALDH7A1 deficiency, PNPO deficiency, PLP binding protein deficiency, hyperprolinemia type II and hypophosphatasia and glycosylphosphatidylinositol anchor synthesis defects). PATIENTS AND METHODS: We conducted a systematic review of published pediatric cases with a confirmed molecular genetic diagnosis of vitamin B6-dependent epilepsy according to PRISMA guidelines. Data on demographic features, seizure semiology, EEG patterns, neuroimaging, treatment, and developmental outcomes were collected. RESULTS: 497 published patients fulfilled the inclusion criteria. Seizure onset manifested at 59.8 ± 291.6 days (67.8% of cases in the first month of life). Clonic, tonic-clonic, and myoclonic seizures accounted for two-thirds of the cases, while epileptic spasms were observed in 7.6%. Burst-suppression/suppression-burst represented the most frequently reported specific EEG pattern (14.4%), mainly in PLPB, ALDH7A1, and PNPO deficiency. Pyridoxine was administered to 312 patients (18.5% intravenously, 76.9% orally, 4.6% not specified), and 180 also received antiseizure medications. Pyridoxine dosage ranged between 1 and 55 mg/kg/die. Complete seizure freedom was achieved in 160 patients, while a significant seizure reduction occurred in 38. PLP, lysine-restricted diet, and arginine supplementation were used in a small proportion of patients with variable efficacy. Global developmental delay was established in 30.5% of a few patients in whom neurocognitive tests were performed. CONCLUSIONS: Despite the wide variability, the most frequent hallmarks of the epilepsy phenotype in patients with vitamin B6-dependent seizures include generalized or focal motor seizure semiology and a burst suppression/suppression burst pattern in EEG

The impact of cultural and religious beliefs on the phenomenology of mental illness in light of the involuntary psychiatric commitment of an East Asian and a West African woman

Religious and cultural issues have become increasingly important in the field of psychiatry. We present two cases which demonstrate the impact of diverse religious beliefs and cultural background on the presentation of mental illness. Clinicians must remain vigilant for the early detection of culturally sanctioned idioms of mental disorders