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OBJECTIVE: Sternal wound infection (SWI) is a rare but potentially life-threatening complication in children following sternotomy. Risk factors include young age, extended preoperative hospitalization, and prolonged ventilatory support. Few studies have explored the impact of pre-existing tracheostomy on SWI in pediatric patients. The purpose of this study is to measure the effect of tracheostomy and other factors on SWI in children undergoing sternotomy. STUDY DESIGN: Retrospective cohort study of a 12 year period. SETTING: Tertiary children's hospital. METHODS: Children with a tracheostomy prior to sternotomy (TPS) were identified and matched by age, height, and weight to children who underwent sternotomy alone. Demographics, medical comorbidities, surgical details, SWI diagnosis and management information, and surgical outcomes were collected. RESULTS: We identified 60 unique individuals representing 80 sternotomies. The incidence of SWI was 22.5% (n = 9) in children with a tracheostomy and 2.5% (n = 1) in those without. The incidence of SWI was greater in children with a tracheostomy (90% vs 10% in those without, P = .007) and underlying pulmonary disease (90% vs 10% in those without, P = .020). Infections in the TPS group also demonstrated greater frequency of Pseudomonas aeruginosa (n = 3) and polymicrobial growth (n = 2). CONCLUSION: The risk of developing a SWI in children undergoing sternotomy is significantly greater in those with a tracheostomy and underlying pulmonary disease. Further study is needed to understand other contributing factors and ways to mitigate this risk.
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Metal hexafluorides hydrolyze at ambient temperature to deposit compounds having fluorine-to-oxygen ratios that depend upon the identity of the metal. Uranium-hexafluoride hydrolysis, for example, deposits uranyl fluoride (UO2F2), whereas molybdenum hexafluoride (MoF6) and tungsten hexafluoride deposit trioxides. Here, we pursue general strategies enabling the prediction of depositing compounds resulting from multi-step gas-phase reactions. To compare among the three metal-hexafluoride hydrolyses, we first investigate the mechanism of MoF6 hydrolysis using hybrid density functional theory (DFT). Intermediates are then validated by performing anharmonic vibrational simulations and comparing with infrared spectra [McNamara et al., Phys. Chem. Chem. Phys. 25, 2990 (2023)]. Conceptual DFT, which is leveraged here to quantitatively evaluate site-specific electrophilicity and nucleophilicity metrics, is found to reliably predict qualitative deposition propensities for each intermediate. In addition to the nucleophilic potential of the oxygen ligands, several other contributing characteristics are discussed, including amphoterism, polyvalency, fluxionality, steric hindrance, dipolar strength, and solubility. To investigate the structure and composition of pre-nucleation clusters, an automated workflow is presented for the simulation of particle growth. The workflow entails a conformer search at the density functional tight-binding level, structural refinement at the hybrid DFT level, and computation of a composite free-energy profile. Such profiles can be used to estimate particle nucleation kinetics. Droplet formation is also considered, which helps to rationalize the different UO2F2 particle morphologies observed under varying levels of humidity. Development of predictive methods for simulating physical and chemical deposition processes is important for the advancement of material manufacturing involving coatings and thin films.
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Severe Plasmodium falciparum malaria infections are caused by microvascular sequestration of parasites binding to the human endothelial protein C receptor (EPCR) via the multi-domain P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion ligands. Using cryogenic electron microscopy (Cryo-EM) and PfEMP1 sequence diversity analysis, we found that group A PfEMP1 CIDRα1 domains interact with the adjacent DBLα1 domain through central, conserved residues of the EPCR-binding site to adopt a compact conformation. Upon EPCR binding, the DBLα1 domain is displaced, and the EPCR-binding helix of CIDRα1 is turned, kinked, and twisted to reach a rearranged, stable EPCR-bound conformation. The unbound conformation and the required transition to the EPCR-bound conformation may represent a conformational masking mechanism of immune evasion for the PfEMP1 family.
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Induction of a lasting protective immune response is dependent on presentation of epitopes to patrolling T cells through the HLA complex. While peptide:HLA (pHLA) complex affinity alone is widely exploited for epitope selection, we demonstrate that including the pHLA complex stability as a selection parameter can significantly reduce the high false discovery rate observed with predicted affinity. In this study, pHLA complex stability was measured on three common class I alleles and 1286 overlapping 9-mer peptides derived from the SARS-CoV-2 Spike protein. Peptides were pooled based on measured stability and predicted affinity. Strikingly, stability of the pHLA complex was shown to strongly select for immunogenic epitopes able to activate functional CD8+T cells. This result was observed across the three studied alleles and in both vaccinated and convalescent COVID-19 donors. Deconvolution of peptide pools showed that specific CD8+T cells recognized one or two dominant epitopes. Moreover, SARS-CoV-2 specific CD8+T cells were detected by tetramer-staining across multiple donors. In conclusion, we show that stability analysis of pHLA is a key factor for identifying immunogenic epitopes.
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COVID-19 , SARS-CoV-2 , Humanos , Epitopos de Linfócito T , Linfócitos T CD8-Positivos , Peptídeos , Antígenos de HistocompatibilidadeRESUMO
BACKGROUND: Adults with Attention-Deficit/Hyperactivity Disorder (ADHD) typically experience poorer attentional control. According to the attention network theory, attentional control relies on three interacting networks of alerting, orienting, and executive control. In ADHD, it is mainly the alerting and executive control networks that are suggested and found to be compromised. METHODS: In the current study, we investigated if a group-based metacognitive remediation program (Goal Management Training [GMT]) in adults with ADHD would enhance attentional control using an experimental measure of the attention network theory. We expected that GMT would specifically enhance the executive control and alerting networks. RESULTS: Data from post- and follow up-assessments of 21 adults (age: 39.05 [11.93]) with ADHD who had completed GMT were included. Linear mixed-effects modeling revealed significant improvements in the functioning of the executive control network for the majority of the participants, although a small subset of participants showed a negative development following the intervention. Results also showed an improvement in the orienting network at follow up, but no change in the alerting network. CONCLUSION: The results may indicate that improvements in the functioning of the executive control network are central to the positive effects of GMT reported in disorders characterized by impaired attentional control. TRIAL REGISTRATION: The study was retrospectively registered in the ISRCTN (Identifier: ISRCTN91988877) on the 18/01/2021.
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Transtorno do Deficit de Atenção com Hiperatividade , Transtornos Cognitivos , Adulto , Função Executiva , Objetivos , Humanos , Pessoa de Meia-Idade , Testes NeuropsicológicosRESUMO
A new and environmentally friendly protocol for the conversion of sugar per-acetates into thioglycosides under solvent free and catalytic conditions is presented. The procedure involves heating in the presence of InCl3 and various aryl thiols. For alkyl thioglycoside synthesis, cyclohexane thiol was found to give good results and yield a glycosyl donor with reactivity similar to a thioethyl congener. The established optimum reaction conditions were found to provide the desired thioglycoside products in an easy and highly diastereoselective manner even when conducted on a multigram scale.
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Tioglicosídeos , Catálise , Glicosilação , Oligossacarídeos , Solventes , Compostos de SulfidrilaRESUMO
Depleted uranium hexafluoride (UF6), a stockpiled byproduct of the nuclear fuel cycle, reacts readily with atmospheric humidity, but the mechanism is poorly understood. We compare several potential initiation steps at a consistent level of theory, generating underlying structures and vibrational modes using hybrid density functional theory (DFT) and computing relative energies of stationary points with double-hybrid (DH) DFT. A benchmark comparison is performed to assess the quality of DH-DFT data using reference energy differences obtained using a complete-basis-limit coupled-cluster (CC) composite method. The associated large-basis CC computations were enabled by a new general-purpose pseudopotential capability implemented as part of this work. Dispersion-corrected parameter-free DH-DFT methods, namely PBE0-DH-D3(BJ) and PBE-QIDH-D3(BJ), provided mean unsigned errors within chemical accuracy (1 kcal mol-1) for a set of barrier heights corresponding to the most energetically favorable initiation steps. The hydrolysis mechanism is found to proceed via intermolecular hydrogen transfer within van der Waals complexes involving UF6, UF5OH, and UOF4, in agreement with previous studies, followed by the formation of a previously unappreciated dihydroxide intermediate, UF4(OH)2. The dihydroxide is predicted to form under both kinetic and thermodynamic control, and, unlike the alternate pathway leading to the UO2F2 monomer, its reaction energy is exothermic, in agreement with observation. Finally, harmonic and anharmonic vibrational simulations are performed to reinterpret literature infrared spectroscopy in light of this newly identified species.
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This article reconsiders traditional topics in nonlinear elastic waves and nonlinear ultrasonics. Herein, higher-order coupling between finite initial deformation and finite amplitude waves are considered. To allow for coupling, a large-on-large deformation model is developed and used to generate the equations of motion relative to the deformed and undeformed material configurations. Thus, the equations of motion provide a single setting to describe topics in nonlinear elastic waves such as acoustoelasticity, second harmonic generation, and coupling relations between these topics. The model is evaluated to recover the traditional linearized acoustoelastic relations and predicted second harmonic amplitudes. Then, the so-called large acoustoelasticity theory is developed for anisotropic materials with specific results given for isotropic materials. Last, the stress influence on second harmonic generation is presented.
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OBJECTIVES: Invasive fungal rhinosinusitis (IFRS) is a potentially fatal disease that affects the severely immunocompromised and requires aggressive treatment. The objective of this study is to better describe predictors of biopsy positivity in patients at high risk of IFRS at a pediatric hospital. METHODS: This was a single-center case-control study of 36 patients (37 total biopsies) ≤ 21 years old with one of five high-risk oncologic/hematologic diagnoses who underwent operative endoscopy for clinical suspicion for IFRS. IFRS positivity was defined histologically. Collected information included patient demographics, primary diagnosis, oncologic relapses, time from diagnosis to biopsy, clinical characteristics, and endoscopic findings. These data were used to create a simple predictive scoring system. RESULTS: 17 patients had biopsy-proven IFRS (IFRS(+)) for an overall incidence of 2.1% in the designated high-risk population. Average time from most recent oncologic development (diagnosis, relapse, or hematopoietic stem-cell transplant) to biopsy in the IFRS(+) group was 2.09 months (SD = 2.26), and 7.28 months in the IFRS(-) group (SD = 9.17) (p = 0.009). Clinical characteristics did not differentiate between IFRS(+) and IFRS(-). Bedside endoscopy performed poorly, as it was interpreted as normal in 42.8% of IFRS(+) and 53.8% of IFRS(-). In contrast, the presence of any positive endoscopic finding intra-operatively was highly specific for IFRS(+) (94%) with moderate sensitivity (70%), and the difference in rate of positivity between groups was statistically significant (p < 0.001). CONCLUSION: Operative endoscopy with biopsy remains the gold-standard to rule-out IFRS in the setting of high clinical suspicion. Time elapsed from most recent oncologic development to clinical concern for IFRS may influence the likelihood of disease, though this requires further study. Clinical symptoms and bedside endoscopy were not predictive and should be used with caution in decision-making.
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Rinite , Sinusite , Adulto , Estudos de Casos e Controles , Criança , Fungos , Hospitais Pediátricos , Humanos , Rinite/terapia , Sinusite/microbiologia , Adulto JovemRESUMO
This case report describes a child who developed Pott's puffy tumor and was treated at the Children's Mercy Hospital in Kansas City. In addition to a discussion of a case, a review of the literature was completed on this topic describing the typical embryology and development of the frontal sinus, and the epidemiology, diagnosis, and treatment of Pott's puffy tumor. The patient was a 23-month-old boy who developed Pott's puffy tumor after recovery from influenza. The patient presented to the hospital with progressing edema of the unilateral eye that spread bilaterally within a few days. A CT scan demonstrated pansinusitis, developed frontal sinuses, right periorbital cellulitis, and medial forehead subperiosteal abscess. Functional endoscopic sinus surgery and transcutaneous abscess drainage were urgently performed and the patient made a full recovery following a course of ertapenem and levofloxacin. The presence of a developed frontal sinus in a 23-month-old is an unexpected radiologic finding. This case represents the youngest patient reported in the literature to develop this rare complication of frontal sinusitis.
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Seio Frontal , Sinusite Frontal , Tumor de Pott , Abscesso/complicações , Abscesso/diagnóstico por imagem , Abscesso/terapia , Seio Frontal/diagnóstico por imagem , Seio Frontal/cirurgia , Sinusite Frontal/complicações , Sinusite Frontal/diagnóstico por imagem , Humanos , Lactente , Masculino , Tumor de Pott/complicações , Tumor de Pott/diagnóstico por imagem , Tumor de Pott/terapia , Doenças Raras/complicações , Doenças Raras/patologiaRESUMO
Background: Adults with attention deficit/hyperactivity disorder (ADHD) are predominantly treated with medication. However, there is also a need for effective, psychologically based interventions. As ADHD is strongly associated with reduced inhibitory control, cognitive remediation approaches should be efficient. Goal management training (GMT) aims at enhancing inhibitory control and has shown positive effects on inhibitory control in non-ADHD patient groups. The aim of the current study was to explore whether GMT would specifically enhance inhibitory control in adults with ADHD, and if such an enhancement would lead to secondary improvements in self-reported everyday functioning. Methods: Twenty-one participants with ADHD (mean age: 39.05 years [SD 11.93]) completed the intervention and assessments pre-, post- and 6 months after the intervention. Measures included neuropsychological tests and self-report questionnaires pertaining to cognitive- and executive functioning, emotion regulation, quality of life, and ADHD symptoms. Results: Compared to baseline, the participants showed enhanced inhibitory control on performance-based measures at post-assessment and 6-month follow-up. The participants also reported increased productivity and reduced cognitive difficulties in everyday life at both assessments post-treatment, as well as improvements in aspects of emotion regulation and a reduction in the severity of core ADHD-symptoms at 6-month follow-up. Conclusion: Our exploratory study showed that GMT seems to specifically improve one of the core executive dysfunctions in ADHD, namely inhibitory control, with a positive effect lasting at least 6 months post-treatment. The adults with ADHD also reported improved self-regulation in their everyday life after completing GMT, providing strong arguments for further investigations of GMT as a treatment option for this group of adults. Clinical Trial Registration: The study is registered under ISRCTN.com (ISRCTN91988877; https://doi.org/10.1186/ISRCTN91988877).
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Tonsillectomy is a very common procedure in children, often performed on an outpatient basis. Severe postoperative pain is common, and can be prolonged. Despite a large number of available analgesic medications, often employed in combination, achieving adequate pain control remains a persistent challenge. Research suggests a tendency among caregivers to undertreat pain, and a need for detailed care instructions and education to ensure adequate pain management. Furthermore, ongoing questions regarding the safety and efficacy of the most commonly used medications have led to wide variance in practice patterns and continuous reassessment through research that yields sometimes conflicting results. This review summarizes the current state of the literature and presents a management approach which attempts to maximize pain control while minimizing potential harm with combinations of medications and modification based on patient-specific factors.
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BACKGROUND: The Functional Movement Screen (FMS™) is a popular test used by sports medicine professionals to identify dysfunctional movement patterns by analyzing mobility and stability during prescribed movements. Although the FMS™ has been a popular topic of research in recent years, normative data and asymmetries in college-aged students have not been established through research. PURPOSE: The objective was to determine normative FMS™ scores, report frequency counts for FMS™ asymmetries, and determine if the number of sports seasons and number of different sports an individual participated in during high school varied between university students that showed FMS™ identified asymmetries. STUDY DESIGN: Cross-sectional Study. METHODS: One hundred university students completed the FMS™ and an associated survey to determine which sport(s) and for how many seasons they participated in each sport(s) during high school. Total FMS™ scores were assessed as well as identifying the presence of an asymmetry during a FMS™ screen. An asymmetry within the FMS™ was defined as achieving an unequal score on any of the screens that assessed right versus left movements of the body. DATA ANALYSIS: Data analysis included descriptive statistics, Pearson correlation was utilized to investigate the relationship between number of sports played and number of sport seasons. Shapiro Wilk test for normality, and Mann Whitney U test was employed to investigate group differences in number of sports played. All analyses were conducted using SPSS software. RESULTS: Statistically significant correlations (r = .286, r2 = .08, p < 0.01) were found for both number of sport seasons and number of sports with FMS™ total score. In addition, participants without FMS™-detected asymmetries played significantly more seasons and more sports than their peers that presented asymmetries (U = 946.5, z = -1.98, p = 0.047). Finish with the actual p-value in parenthesis. CONCLUSION: Participating in multiple sports and multiple sport seasons during high school was associated with higher FMS™ total scores. Results suggest that participating in multiple sports and multiple sport seasons was associated with fewer asymmetries, which may decrease subsequent injury risk. LEVEL OF EVIDENCE: 3b.
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BACKGROUND: There is growing evidence for the efficacy of group-based interventions for adults with ADHD. However, there is still a lack of research investigating how clients experience participating in such interventions. The aim of the current study was to explore how adults with ADHD experience participating in a group-based intervention (Goal Management Training) for ADHD. METHOD: We conducted individual, semi-structured, interviews with ten adults with ADHD who had participated in Goal Management Training administered as a group intervention. The interviews were transcribed verbatim and analyzed using thematic analysis within a hermeneutic phenomenological framework. RESULTS: Our analysis identified three main themes. The participants' starting point captured the participants' motivation and expectations prior to treatment. The ambiguity of the group - the various meanings of the group consisted of three sub-themes (The group created a sense of belonging - "I am not alone"; The personal cost of participating in the group - "At times it was a hot mess"; and The group supported the learning experience - "We worked with it together"). The group promoted positive change - How the group affected the participants' everyday lives consisted of two sub-themes (Managing ADHD in daily life - "It's much easier to handle everyday life", and Personal growth - "Gaining new perspectives"). CONCLUSION: The group format was experienced as a valuable aspect of treatment. The structure provided by Goal Management Training allowed participants to expand their perspectives and experience improved management of ADHD, as well as personal growth. The opportunity to exchange experiences with others in similar situations was seen as particularly beneficial and brought feelings of recognition and belonging. However, some also experienced the group as a burden at times, for instance by stealing one's focus. This study expands existing knowledge by exploring clients' experiences of participating in group-based interventions for ADHD and shows how the group format provided participants with more than they had hoped for. While expecting a more instrumental outcome of treatment, such as tools to manage ADHD, participants also gained a welcomed, but unexpected outcome of personal growth.
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Transtorno do Deficit de Atenção com Hiperatividade , Motivação , Adulto , Transtorno do Deficit de Atenção com Hiperatividade/terapia , Objetivos , Esperança , Humanos , Pesquisa QualitativaRESUMO
Objective: To investigate test-retest reliability of the 25-item version of Wender Utah Rating Scale (WURS-25) and factors influencing retrospective reports of childhood behavior in adults with ADHD. Method: Eighty-five adults with ADHD and 189 controls completed the WURS-25 and the adult ADHD Self-Rating Scale (ASRS) at two time points (mean interval = 7 years) and provided information about dyslexia, somatic, and psychiatric disorders. Results: The correlation between WURS-25 scores at the two time points was strong, and reports from 60% of the adults with ADHD showed no change in severity level. Reports on the WURS-25 were positively associated with current ADHD symptoms at both time points and the presence of dyslexia and mood disorders, with the strongest association found among adults reporting the most severe WURS-25 score. Conclusion: Although our study showed an acceptable test-retest reliability of WURS-25, the substantial contribution from current ADHD symptoms to the WURS scores emphasizes the importance of collateral information from family members and others who knew the adult in childhood.
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Transtorno do Deficit de Atenção com Hiperatividade , Adulto , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Criança , Humanos , Escalas de Graduação Psiquiátrica , Reprodutibilidade dos Testes , Estudos Retrospectivos , Utah/epidemiologiaRESUMO
INTRODUCTION: Tracheostomy in children is often performed to alleviate airway obstruction (AO) or to facilitate long-term ventilator support due to respiratory failure of various etiologies, such as heart failure, and postoperative respiratory failure. Although many of these pathologies are common among trisomy 21 patients, tracheostomy rates among this population have not previously been reported. The aim of our study was to determine the incidence of trisomy 21 patients undergoing tracheostomy. Secondary objectives include decannulation rates and mortality associated with tracheostomy. MATERIALS AND METHODS: A retrospective cohort study was conducted on pediatric trisomy 21 patients undergoing tracheostomy between 2004 and 2013. RESULTS: Twenty patients underwent tracheostomy at a median age of 7.1 months (interquartile range [IQR] = 3.5,21.3). The estimated incidence of tracheostomy in trisomy 21 patients among our tracheostomy population was 1.7% (20/1173) over 10 years. The most common indications were airway obstruction (AO) (55%), cardiac/pulmonary respiratory failure (CRF) (25%), or both (20%). Overall mortality was 30%, much lower among AO patients (9%) than CRF (40%) or both (60%), (P = 0.029). Nine patients (45%) were successfully decannulated, with median duration of cannulation of 2.2 years (IQR = 1.7,3). CONCLUSIONS: This study suggests a rate of tracheostomy in the pediatric trisomy 21 population approximately 3 times that of the general pediatric population. Over half in this cohort underwent tracheostomy for isolated AO, while the general pediatric tracheostomy population demonstrates a much higher prevalence of prematurity-related CRF. Overall mortality rate and decannulation rate approximated that of the general pediatric tracheostomy population, although outcomes were significantly poorer among patients trisomy 21 patients undergoing tracheostomy for CRF.
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Síndrome de Down , Obstrução das Vias Respiratórias/epidemiologia , Obstrução das Vias Respiratórias/cirurgia , Estudos de Coortes , Síndrome de Down/epidemiologia , Humanos , Lactente , Estudos Retrospectivos , TraqueostomiaRESUMO
The outbreak of SARS-CoV-2 (2019-nCoV) virus has highlighted the need for fast and efficacious vaccine development. Stimulation of a proper immune response that leads to protection is highly dependent on presentation of epitopes to circulating T-cells via the HLA complex. SARS-CoV-2 is a large RNA virus and testing of all of its overlapping peptides in vitro to deconvolute an immune response is not feasible. Therefore HLA-binding prediction tools are often used to narrow down the number of peptides to test. We tested NetMHC suite tools' predictions by using an in vitro peptide-MHC stability assay. We assessed 777 peptides that were predicted to be good binders across 11 MHC alleles in a complex-stability assay and tested a selection of 19 epitope-HLA-binding prediction tools against the assay. In this investigation of potential SARS-CoV-2 epitopes we found that current prediction tools vary in performance when assessing binding stability, and they are highly dependent on the MHC allele in question. Designing a COVID-19 vaccine where only a few epitope targets are included is therefore a very challenging task. Here, we present 174 SARS-CoV-2 epitopes with high prediction binding scores, validated to bind stably to 11 HLA alleles. Our findings may contribute to the design of an efficacious vaccine against COVID-19.
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Vacinas contra COVID-19/imunologia , COVID-19/prevenção & controle , Biologia Computacional/métodos , Epitopos de Linfócito T/imunologia , Aprendizado de Máquina , SARS-CoV-2/imunologia , Alelos , Sequência de Bases , COVID-19/virologia , Antígenos HLA/genética , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe II/genética , Humanos , Peptídeos/genética , Peptídeos/imunologia , Glicoproteína da Espícula de Coronavírus/genéticaRESUMO
INTRODUCTION: Substance use disorders and insomnia are common in the general population, and particularly among adults with attention-deficit/hyperactivity disorder (ADHD). Here we investigated the relationship between insomnia, alcohol consumption and ADHD symptoms. METHODS: Adults with an ADHD diagnosis (n = 235, 41.3% males) and controls (n = 184, 38% males) completed a questionnaire assessing insomnia (Bergen Insomnia Scale), alcohol consumption (Alcohol Use Disorders Identification Test), and current ADHD symptoms (Adult ADHD Self-report Scale). The majority of the sample (95%) gave additional information about childhood ADHD symptoms (Wender Utah Rating Scale), and information about lifetime occurrence of an internalizing disorder was included as part of background information. RESULTS: Compared to controls, the ADHD group reported a higher frequency of insomnia, a higher quantity of consumed alcohol and a higher frequency of internalizing disorders. Current and childhood ADHD symptoms were more severe in those with than without insomnia. Scores on ADHD symptom scales were explained by the presence of insomnia and internalizing disorders, while the contribution from alcohol consumption was restricted to the control group. DISCUSSION: The high functional impact of insomnia, alcohol misuse and internalizing disorders is well known. The present study contributed by focusing on their relations to ADHD symptoms, and by showing that strong relations were not restricted to adults with a clinical ADHD diagnosis. By this, the results put a critical light on a categorical delineation between adults with an ADHD diagnosis and population selected controls, and call for further studies including dimensional metrics of ADHD symptoms and co-occurring problems.
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Electric field-based frequency tuning of acoustic resonators at the material level may provide an enabling technology for building complex tunable filters. Tunable acoustic resonators were fabricated in thin plates (h/ λ â¼ 0.05 ) of X-cut lithium niobate (LiNbO3) (90°, 90°, ψ = 170° ). LiNbO3 is known for its large electromechanical coupling ( K 2 ) for the shear and symmetric Lamb modes (SH0: K 2 = 40 %, S0: K 2 = 30 %) in thin plates and, thus, applicability for low-insertion loss and wideband filter applications. We demonstrate the effect of a dc bias in X-cut LiNbO3 to shift the resonant frequency by ~0.4% through direct tuning of the resonator material. A nonlinear acoustic computation predicted 0.36% tuning, which was in excellent agreement with the tuning measurement. For X-cut, we predicted electrical tuning of the S0 mode up to 1.6% and for Y-cut the electrical tuning of the SH0 and S0 modes was up to 7.0% with K 2 = 27.1 %. The mechanism is based on the nonlinearities that exist in the piezoelectric properties of LiNbO3. The X-cut SH0 mode resonators were centered near 335 MHz and achieved a frequency tuning of 6 kHz/V through the application of a dc bias.