Blue emitting exciplex for yellow and white organic light-emitting diodes.

White organic light-emitting diodes (WOLEDs) have several desirable features, but their commercialization is hindered by the poor stability of blue light emitters and high production costs due to complicated device structures. Herein, we investigate a standard blue emitting hole transporting material (HTM) N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) and its exciplex emission upon combining with a suitable electron transporting material (ETM), 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ). Blue and yellow OLEDs with simple device structures are developed by using a blend layer, NPB:TAZ, as a blue emitter as well as a host for yellow phosphorescent dopant iridium (III) bis(4-phenylthieno[3,2-c]pyridinato-N,C2')acetylacetonate (PO-01). Strategic device design then exploits the ambipolar charge transport properties of tetracene as a spacer layer to connect these blue and yellow emitting units. The tetracene-linked device demonstrates more promising results compared to those using a conventional charge generation layer (CGL). Judicious choice of the spacer prevents exciton diffusion from the blue emitter unit, yet facilitates charge carrier transport to the yellow emitter unit to enable additional exciplex formation. This complementary behavior of the spacer improves the blue emission properties concomitantly yielding reasonable yellow emission. The overall white light emission properties are enhanced, achieving CIE coordinates (0.36, 0.39) and color temperature (4643 K) similar to daylight. Employing intermolecular exciplex emission in OLEDs simplifies the device architecture via its dual functionality as a host and as an emitter.

Substituent-Controlled Photophysical Responses in Dihydropyridine Derivatives and Their Application in the Detection of Volatile Organic Contaminants.

In the ever-expanding realm of organic fluorophores, structurally simple and synthetically straightforward molecules with unique photophysical properties have received special attention. Among these, 1,4-dihydropyridine (DHP) is an important scaffold that permits fine-tuning of their photophysical properties through substituents on the periphery. Herein, we describe a series of solid-emissive N-substituted 2,6-dimethyl-4-methylene-1,4-dihydropyridine derivatives appended with electron-withdrawing substituents (dicyanomethylene or 2-dicyanomethylene-3-cyano-2,5-dihydrofuran) at the C-4 position and alkyl or alkylaryl groups on the DHP nitrogen. Electronic and steric tuning exerted by these substituents resulted in interesting photophysical properties such as negative solvatochromism, solidstate, and aggregation-induced emission (AIE). Theoretical calculations were carried out to explain the solvatochromic properties. Insight into the AIE properties was obtained through variable-temperature nuclear magnetic resonance and viscosity- and temperature-dependent emission studies. The variations in molecular packing in the crystal lattice with changes in the N-substituents contributed to the tuning of solid state emission properties. Detection of aromatic volatile organic compounds (VOCs) was achieved using the aggregates of the DHP derivatives. Among the VOCs, p-xylene elicited a significant enhancement in emission, allowing its detection at submicromolar levels.

Thermally Activated Delayed Fluorescent Solvent-free Organic Liquid Hybrids for Tunable Emission Applications.

The synthetic feasibility and excellent luminescence features of organic molecules attracted much attention and were eventually found useful in lighting applications. In this context, a solvent-free organic liquid having attractive thermally activated delayed fluorescence features in bulk along with high processability has prime importance. Herein, we report a series of naphthalene monoimide-based solvent-free organic liquids exhibiting cyan to red thermally activated delayed fluorescence with luminescence quantum yields up to 80% and lifetimes between 10 to 45 µs. An effective approach explored energy transfer between liquid donors with various emitters exhibiting tunable emission colors, including white. The high processability of liquid emitters improved the compatibility with polylactic acid and was used for developing multicolor emissive objects using 3D printing. Our demonstration of the thermally activated delayed fluorescence liquid will be much appreciated as a processable alternate emissive material suitable for large-area lighting, display, and related applications.

ACR Appropriateness Criteria® Ataxia-Child.

Childhood ataxia may be due to multifactorial causes of impairment in the coordination of movement and balance. Acutely presenting ataxia in children may be due to infectious, inflammatory, toxic, ischemic, or traumatic etiology. Intermittent or episodic ataxia in children may be manifestations of migraine, benign positional vertigo, or intermittent metabolic disorders. Nonprogressive childhood ataxia suggests a congenital brain malformation or early prenatal or perinatal brain injury, and progressive childhood ataxia indicates inherited causes or acquired posterior fossa lesions that result in gradual cerebellar dysfunction. CT and MRI of the central nervous system are the usual modalities used in imaging children presenting with ataxia, based on the clinical presentation. This document provides initial imaging guidelines for a child presenting with acute ataxia with or without a history of recent trauma, recurrent ataxia with interval normal neurological examination, chronic progressive ataxia, and chronic nonprogressive ataxia. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Amplified Spontaneous Emission from Zwitterionic Excited-State Intramolecular Proton Transfer.

The unique four-level photocycle characteristics of excited-state intramolecular proton transfer (ESIPT) materials enable population inversion and large spectral separation between absorption and emission through their respective enol and keto forms. This leads to minimal or no self-absorption losses, a favorable feature in acting as an optical gain medium. While conventional ESIPT materials with an enol-keto tautomerism process are widely known, zwitterionic ESIPT materials, particularly those with high photoluminescence, are scarce. Facilitated by the synthesis and characterization of a new family of 2-hydroxyphenyl benzothiazole (HBT) with fluorene substituents, HBT-Fl1 and HBT-Fl2, we herein report the first efficient zwitterionic ESIPT lasing material (HBT-Fl2). The zwitterionic ESIPT HBT-Fl2 not only shows a remarkably low solid-state amplified spontaneous emission (ASE) threshold of 5.3 µJ/cm2 with an ASE peak at 609 nm but also exhibits high ASE photostability. Coupled with its substantially large Stokes shift (≈236 nm ≈10,390 cm-1) and an extremely small overlap of excited-state absorption with ASE emission, comprehensive density functional theory (DFT) and time-dependent DFT studies reveal the zwitterionic characteristics of HBT-Fl2. In opposition to conventional ESIPT with π-delocalized tautomerism as observed in analogue HBT-Fl1 and parent HBT, HBT-Fl2 instead shows charge redistribution in the proton transfer through the fluorene conjugation. This structural motif provides a design tactic in the innovation of new zwitterionic ESIPT materials for efficient light amplification in red and longer-wavelength emission.

Association between loneliness, self-esteem and outcome of life satisfaction in Norwegian adolescents aged 15-21.

AIMS: Adolescence is an important developmental stage for understanding the role of perceived loneliness and self-esteem on life satisfaction. This study investigated the association between loneliness, self-esteem and the outcome of life satisfaction, as well as potential interaction effects in association with life satisfaction, in a sample of Norwegian adolescents. METHODS: The study was based on a cross-sectional sample of 1816 adolescents aged 15-21 years. Data were collected in September 2016. The participants reported scores on the five-item Satisfaction with Life Scale, the 10-item Rosenberg Self-Esteem Scale and one item assessing loneliness. Control variables included sex, age, perceived family economy, parents' education, place of birth and perceived bullying. The data were analysed with descriptive and multiple linear regression analysis. RESULTS: A significant negative and moderately strong association was found between loneliness and life satisfaction, where the association was stronger for girls than for boys. Self-esteem showed a significant positive and strong association with life satisfaction; however, no significant interaction effect was found. CONCLUSIONS: The findings show the significant role of both loneliness and self-esteem in association with adolescents' perception of life satisfaction. The findings support promoting self-esteem, belongingness and social integration in all daily life contexts for adolescents to support their life satisfaction.

The role of perceived loneliness and sociodemographic factors in association with subjective mental and physical health and well-being in Norwegian adolescents.

AIMS: Adolescence is a particularly salient period for understanding the role of perceived loneliness for subjective health and well-being. This study investigated sociodemographic differences (sex, age, self-reported socio-economic status (SES)) in loneliness and associations between sociodemographic factors, loneliness and self-rated health (SRH), subjective health symptoms, symptoms of depression/anxiety and mental well-being (MWB) in a sample of Norwegian adolescents. METHODS: The study was based on a cross-sectional sample of 1816 adolescents aged 15-21 years. The participants reported scores on an 11-item scale assessing subjective health complaints (SHC), one item each assessing SRH and loneliness, the 10-item version of the Hopkins Symptom Checklist and the seven-item version of the Warwick-Edinburgh Mental Well-Being Scale. SES was assessed using perceived family economy and parents' education. Data were analysed with descriptive, comparative and multiple linear regression analyses. RESULTS: The multivariate results showed that boys scored significantly higher on MWB than girls did, whereas girls scored significantly higher on loneliness, depression/anxiety and SHC. Perceptions of poorer family finances were significantly associated with higher levels of SHC and depression/anxiety, lower levels of MWB and more negative SRH. Loneliness showed significant positive associations with depression/anxiety and SHC, and significant negative associations with MWB and SRH. A significant moderation effect of sex by loneliness was found in association with depression/anxiety, with stronger associations for girls. CONCLUSIONS: The findings in this study support the significant roles of sex, perceptions of family finances and loneliness in association with adolescent's subjective mental and physical health and well-being, especially mental health.

ACR Appropriateness Criteria® Seizures-Child.

In children, seizures represent an extremely heterogeneous group of medical conditions ranging from benign cases, such as a simple febrile seizure, to life-threatening situations, such as status epilepticus. Underlying causes of seizures also represent a wide range of pathologies from idiopathic cases, usually genetic, to a variety of acute and chronic intracranial or systemic abnormalities. This document discusses appropriate utilization of neuroimaging tests in a child with seizures. The clinical scenarios in this document take into consideration different circumstances at the time of a child's presentation including the patient's age, precipitating event (if any), and clinical and electroencephalogram findings and include neonatal seizures, simple and complex febrile seizures, post-traumatic seizures, focal seizures, primary generalized seizures in a neurologically normal child, and generalized seizures in neurologically abnormal child. This practical approach aims to guide clinicians in clinical decision-making and to help identify efficient and appropriate imaging workup. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Magnetic resonance imaging quality control, quality assurance and quality improvement.

Quality in MR imaging is a comprehensive process that encompasses scanner performance, clinical processes for efficient scanning and reporting, as well as data-driven improvement involving measurement of key performance indicators. In this paper, the authors review this entire process. This article provides a framework for establishing a successful MR quality program. The collective experiences of the authors across a spectrum of pediatric hospitals is summarized here.

Performance of overnight on-call radiology residents in interpreting unenhanced abdominopelvic magnetic resonance imaging studies performed for pediatric right lower quadrant abdominal pain.

BACKGROUND: Abdominopelvic magnetic resonance imaging (MRI) is increasingly being used to evaluate children with abdominal pain suspected of having acute appendicitis. At our institution, these examinations are preliminarily interpreted by radiology residents, especially when performed after hours. OBJECTIVE: To determine the accuracy of preliminary reports rendered by radiology residents in this setting. MATERIALS AND METHODS: Three hundred seventy-seven pediatric abdominopelvic MRI examinations were included. The preliminary (resident) and final (attending) radiology reports were coded as diagnosing acute appendicitis or no acute appendicitis. The concordance between resident and attending radiologist interpretations was calculated. Additionally, both resident and attending reports were compared to available surgical pathology or clinical follow-up data. RESULTS: Overall concordance rate for the diagnosis of acute appendicitis was 97.1%. Concordance for verified cases of acute appendicitis was 93.4%. Concordance rates did not differ by residents' postgraduate year levels. When compared against surgical pathology or clinical follow-up data, residents demonstrated 91.2% sensitivity and 97.6% specificity. There was no statistically significant difference in the sensitivity or specificity of resident or attending radiologist interpretations. CONCLUSION: Radiology residents demonstrate high concordance with attending pediatric radiologists in their interpretations of pediatric abdominopelvic MRI for acute appendicitis. The diagnostic performances of residents and attendings were comparable.

Butterfly-Shaped Thiophene-Pyridine Hybrids: Green Electroluminescence and Large Third-Order Optical Nonlinearities.

A set of four symmetric, butterfly-shaped 4-(4-(decyloxy)phenyl)-2,6-di(thiophen-2-yl)pyridine (TPY) derivatives 2TPA-TPY (TPY center and triphenylamine end groups), 2CBZ-TPY (TPY center and N-ethyl carbazole end groups), 2TPY-TPA (triphenylamine center and TPY at the periphery) and 2TPY-CBZ (N-ethyl carbazole center and TPY at the periphery) was synthesized. The molecules show reverse saturable absorption (RSA) which is consistent with two-photon absorption (2PA) associated with excited-state absorption (ESA) when excited using a 532 nm laser beam. The molecules 2TPA-TPY and 2TPY-TPA possess extremely low limiting thresholds of 1.73 and 2.68 J cm-2 , respectively. An organic light-emitting diode (OLED) fabricated from 2TPA-TPY exhibits green emission with a maximum luminance of 207 cd m-2 , a current efficiency (ηCE ) of 1.51cd A-1 , a maximum power efficiency (ηPmax ) of 0.46 lm W-1 and an external quantum efficiency (ηEQE ) of 0.48 % at 100 cd m-2 .

ACR Appropriateness Criteria® Head Trauma-Child.

Head trauma is a frequent indication for cranial imaging in children. The majority of accidental pediatric head trauma is minor and sustained without intracranial injury. Well-validated pediatric-specific clinical decision guidelines should be used to identify very low-risk children who can safely forgo imaging. In those who require acute imaging, CT is considered the first-line imaging modality for suspected intracranial injury because of the short duration of the examination and its high sensitivity for acute hemorrhage. MRI can accurately detect traumatic complications, but often necessitates sedation in children, owing to the examination length and motion sensitivity, which limits rapid assessment. There is a paucity of literature regarding vascular injuries in pediatric blunt head trauma and imaging is typically guided by clinical suspicion. Advanced imaging techniques have the potential to identify changes that are not seen by standard imaging, but data are currently insufficient to support routine clinical use. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Cerebrovascular Disease-Child.

Stroke is an uncommon but an important and under-recognized cause of morbidity and mortality in children. Strokes may be due to either brain ischemia or intracranial hemorrhage. Common symptoms of pediatric acute stroke include headache, vomiting, focal weakness, numbness, visual disturbance, seizures, and altered consciousness. Most children presenting with an acute neurologic deficit do not have an acute stroke, but have symptoms due to stroke mimics which include complicated migraine, seizures with postictal paralysis, and Bell palsy. Because of frequency of stroke mimics, in children and the common lack of specificity in symptoms, the diagnosis of a true stroke may be delayed. There are a relatively large number of potential causes of stroke mimic and true stroke. Consequently, imaging plays a critical role in the assessment of children with possible stroke and especially in children who present with acute onset of stroke symptoms. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

First-Line Diagnostic Evaluation with MRI of Children Suspected of Having Acute Appendicitis.

Background Advances in abdominal MRI have enabled rapid, free-breathing imaging without the need for intravenous or oral contrast material. The use of MRI as the primary imaging modality for suspected appendicitis has not been previously studied. Purpose To determine the diagnostic performance of MRI as the initial imaging modality in children suspected of having acute appendicitis. Materials and Methods The study included consecutive patients 18 years of age and younger presenting with acute abdominal pain at a tertiary care institution from January 2013 through June 2016 who subsequently underwent an unenhanced MRI examination as the primary diagnostic imaging modality. Electronic medical records and radiology reports were retrospectively evaluated for the feasibility and diagnostic performance of MRI, with surgical pathology and follow-up electronic records as reference standards. Statistical analyses were performed by using simple binomial proportions to quantify sensitivity, specificity, and accuracy, and exact 95% confidence intervals (CIs) were obtained. Results After exclusions, 402 patients (median age: 13 years; interquartile range [IQR], 9-15 years; 235 female patients; 167 male patients) were included. Sedation for MRI was required in 13 of 402 patients (3.2%; 95% CI: 1.7%, 5.5%). The appendix was visualized in 349 of 402 patients (86.8%; 95% CI: 83.1%, 90%); for the remaining patients, a diagnosis was provided on the basis of secondary signs of appendicitis. The sensitivity, specificity, and accuracy of MRI as the primary diagnostic imaging modality for the evaluation of acute appendicitis were 97.9% (95 of 97; 95% CI: 92.8%, 99.8%), 99% (302 of 305; 95% CI: 97.2%, 99.8%), and 98.8% (397 of 402; 97.1%, 99.6%), respectively. Among patients with negative findings for appendicitis at MRI, an alternate diagnosis was provided in 113 of 304 patients (37.2%; 95% CI: 31.7%, 42.9%). Conclusion When performed as the initial imaging modality in children suspected of having acute appendicitis, MRI examinations had high diagnostic performance for the diagnosis of acute appendicitis and in providing alternative diagnoses. © RSNA, 2019 See also the editorial by Dillman and Trout in this issue.

Modelling and forecasting Positive and Negative Syndrome Scale scores to achieve remission using time series analysis.

OBJECTIVES: Schizophrenia is a chronic mental condition. The objective of this study is to apply time series modelling to Positive and Negative Syndrome Scale scores of outpatients with schizophrenia, observed at regular intervals of time, and hence forecast the number of visits required to reach remission. METHODS: A retrospective data of outpatients diagnosed with chronic paranoid-type schizophrenia were extracted from the records of outpatient department of a tertiary hospital in New Delhi, India. Autoregressive integrated moving average (ARIMA) and ARIMAX models (ARIMA with explanatory variable as Clinical Global Impression Severity scale) are fitted to the data. The best fit models are employed to forecast the number of visits required to reach remission for the outpatients who did not achieve remission by the end of study. Prediction accuracy of the two models is compared using mean absolute percentage error and mean absolute deviation. RESULTS: The ARIMA (1, 2, 1) and ARIMAX (1, 2, 1) models are identified to be suitable models after a series of statistical tests. CONCLUSIONS: ARIMA and ARIMAX models are suitable to predict number of visits required to reach remission. Further, ARIMAX model performed better than ARIMA model.

The association between stress, resilience, and emotional symptoms in Norwegian adolescents from 13 to 18 years old.

This study investigated associations between stress, resilience factors, and symptoms of depression and anxiety in a cross-sectional sample of 1183 adolescents 13-18 years old. The results showed a positive significant association between stress and symptoms of depression and anxiety. Personal competence was significantly negatively associated with depression and anxiety, whereas social support was significantly negatively associated with anxiety. Significant interaction effects were found between gender by personal competence and gender by structured style in relation to anxiety, with stronger associations for girls. A compensatory role of resilience was found on the relation between stress and emotional symptoms.

The Relationship Between Positive Mental Health Literacy and Mental Well-Being Among Adolescents: Implications for School Health Services.

Mental health education is a central part of school nurses' practice. Mental health literacy is an asset for health that educational initiatives can strengthen, and a significant determinant of mental health. This study was intended to examine the relationship between positive mental health literacy (PMeHL) and mental well-being to discuss its implications for school health services' mental health education. The relationship was assessed using a multiple linear regression model controlling for relevant covariates. Data were derived from a cross-sectional school-based survey including 1,888 adolescents aged 15-21 years (response rate 97.3%). A weak gender difference was found in PMeHL. The regression model accounted for 41% of the variance in adolescents' mental well-being; PMeHL was a significant explanatory variable of mental well-being. Accordingly, the current study found support for including PMeHL, or knowledge of how to obtain and maintain good mental health, as an integral component of school health services' mental health education among adolescents.

Life satisfaction in association with self-efficacy and stressor experience in adolescents - self-efficacy as a potential moderator.

AIM: This paper reports associations among socio-demographic variables, stressor experience, self-efficacy and life satisfaction among Norwegian adolescents aged 15-21 years and the potential moderating role of self-efficacy on the association between stressor experience and life satisfaction. METHODS: The cross-sectional school-based survey study involved 1816 upper-secondary school students from Mid-Norway. Data were analysed with independent samples t test, Pearson's product moment correlation and multiple linear regression analysis. RESULTS: Bivariate results showed that boys scored higher than girls on life satisfaction and self-efficacy, whereas girls scored higher than boys on all stressor domains. Multiple linear regression analysis showed that life satisfaction declined weakly with age, whereas stronger family economy and having parents who work full-time associated with higher life satisfaction. Stress with teacher interaction, peer pressure, home life, school attendance, school-leisure conflict and school performance were all negatively associated with life satisfaction, whereas self-efficacy associated positively and strongly with life satisfaction. Self-efficacy moderated the association between both interpersonal and school-related stressors and life satisfaction. CONCLUSION: The results provide support for the unique role of stressor experience and self-efficacy in association with adolescents' life satisfaction as well as self-efficacy as a stress moderator in relation to life satisfaction.

Jugular bulb and skull base pathologies: proposal for a novel classification system for jugular bulb positions and microsurgical implications.

OBJECTIVE There is no definitive or consensus classification system for the jugular bulb position that can be uniformly communicated between a radiologist, neurootologist, and neurosurgeon. A high-riding jugular bulb (HRJB) has been variably defined as a jugular bulb that rises to or above the level of the basal turn of the cochlea, within 2 mm of the internal auditory canal (IAC), or to the level of the superior tympanic annulus. Overall, there is a seeming lack of consensus, especially when MRI and/or CT are used for jugular bulb evaluation without a dedicated imaging study of the venous anatomy such as digital subtraction angiography or CT or MR venography. METHODS A PubMed analysis of "jugular bulb" comprised of 1264 relevant articles were selected and analyzed specifically for an HRJB. A novel classification system based on preliminary skull base imaging using CT is proposed by the authors for conveying the anatomical location of the jugular bulb. This new classification includes the following types: type 1, no bulb; type 2, below the inferior margin of the posterior semicircular canal (SCC), subclassified as type 2a (without dehiscence into the middle ear) or type 2b (with dehiscence into the middle ear); type 3, between the inferior margin of the posterior SCC and the inferior margin of the IAC, subclassified as type 3a (without dehiscence into the middle ear) and type 3b (with dehiscence into the middle ear); type 4, above the inferior margin of the IAC, subclassified as type 4a (without dehiscence into the IAC) and type 4b (with dehiscence into the IAC); and type 5, combination of dehiscences. Appropriate CT and MR images of the skull base were selected to validate the criteria and further demonstrated using 3D reconstruction of DICOM files. The microsurgical significance of the proposed classification is evaluated with reference to specific skull base/posterior fossa pathologies. RESULTS The authors validated the role of a novel classification of jugular bulb location that can help effective communication between providers treating skull base lesions. Effective utilization of the above grading system can help plan surgical procedures and anticipate complications. CONCLUSIONS The authors have proposed a novel anatomical/radiological classification system for jugular bulb location with respect to surgical implications. This classification can help surgeons in complication avoidance and management when addressing HRJBs.