Scientometrics of Scientometrics: Mapping Historical Footprint and Emerging Technologies in Scientometrics

Scientometrics is the study of quantitative aspects of science, technology, and innovation. This chapter identifies thematic patterns and emerging trends of the published literature in scientometrics using a variety of tools and techniques, including CiteSpace, VOSviewer, and dynamic topic modeling. Using 8098 bibliographic records of published scientometrics research, we explored domain-level citation paths, subject category assignment, keyword co-occurrence, topic models, and document co-citation network to map and characterize the intellectual landscapes of scientometrics. Findings reveal that the domain is multidisciplinary in that a wide range of disciplines contribute to the growth of literature, but only partially interdisciplinary as some works heavily cites from similar domains. Early literature was interested in measuring the impact of a science and evaluating research performance and productivity. Modeling scientometrics laws and indicators is also of greatest interest. Later work explored applications of scientometrics to a variety of domains such as material sciences, medicine, environmental sciences, and social media analytics. Impact measure and science mapping are among the topics receiving consistent attention

An unusual cause of duodenal perforation due to a lollipop stick

Children have a natural tendency to explore objects with their mouths; this can result in the swallowing of foreign objects. Most ingested foreign bodies pass uneventfully through the gastrointestinal tract. However, some foreign bodies cause obstruction or perforation of the gastrointestinal tract, requiring surgical intervention. Perforation of the gastrointestinal tract may be associated with considerable morbidity and mortality. The most common sites of intestinal foreign body perforation are the ileocecal and rectosigmoid regions. Foreign body perforation of the duodenum is relatively uncommon. We report the first Korean case of duodenal perforation by an ingested 8-cm lollipop stick. Lollipops are popular with the children and fairly accessible to them, as most parents are not aware of their potential harm. Pediatric clinicians should be aware of the risks associated with lollipop stick ingestion. Our report also describes the feasibility and safety of laparoscopic diagnosis and management of pediatric patients with peritonitis induced by the ingestion of foreign bodies

Optogenetics: Solving the Enigma of Sleep

Sleep is a crucial and evolutionarily conserved phenomenon, but the mechanisms that control sleep-wake behavior and underlie sleep disorders are not yet fully understood. One major challenge for sleep research was the lack of technology that allows for cell-type- and circuit-specific investigation of neurons and neural circuitry. A decade ago, a novel methodology known as optogenetics was developed, which uses light to control specific cell types of neurons, either to activate or inhibit neuronal firings. The strength of optogenetics in neuroscience is the precise control of neuronal activities in millisecond scale and the ability to dissect the neural circuits and cell types to understand their functions. There have been substantial advancements made in the field of sleep research through the implementation of optogenetics. This review provides a brief introduction on the optogenetics and a consolidated summary of recent findings published in sleep research using optogenetics

Vascular Injury Associated with Blunt Trauma without Dislocation of the Knee

Failure to recognize popliteal artery injury and restore vessel continuity of flow after blunt trauma is a major cause of lower extremity amputation and morbidity. A high index of suspicion and early recognition of the injury are paramount for limb salvage. We experienced a rare case of poplitial artery occlusion with the presence of arterial pulses due to collateral circulation after blunt trauma. Expeditious revascularization was achieved by using posterior approach, allowing two surgical teams to work simultaneously. This case illustrates that, even in the absence of knee dislocation, surgeons must always consider the possibility of a popliteal artery damage whenever a blunt trauma near the knee

Withdrawal of Immunosuppression in Pediatric Liver Transplant Recipients in Korea

Purpose: We identified pediatric liver transplant recipients with successful withdrawal of immunosuppression who developed tolerance in Korea. Materials and Methods: Among 105 pediatric patients who received liver transplantation and were treated with tacrolimus-based immunosuppressive regimens, we selected five (4.8%) patients who had very low tacrolimus trough levels. Four of them were noncompliant with their medication and one was weaned off of immunosuppression due to life threatening posttransplant lymphoproliferative disorder. We reviewed the medical records with regard to the relationship of the donor-recipients, patient characteristics and prognosis, including liver histology, and compared our data with previous reports. Results: Four patients received the liver transplantation from a parent donor and one patient from a cadaver donor. A trial of withdrawal of the immunosuppressant was started a median of 45 months after transplantation (range, 14 months to 60 months), and the period of follow up after weaning from the immunosuppressant was a median of 32 months (range, 14 months to 82 months). None of the five patients had rejection episodes after withdrawal of the immunosuppression; they maintained normal graft function for longer than 3 years (median, 38 months; range, 4 to 53 months). The histological findings of two grafts 64 and 32 months after weaning-off of the medication showed no evidence of chronic rejection. Conclusion: The favorable markers for successful withdrawal of immunosuppression were 1) long-term (> 3 years) stable graft function, 2) no rejection for longer than 1 year after withdrawal of immunosuppression

Prognostic factors in children with extracranial germ cell tumors treated with cisplatin-based chemotherapy

PurposeTo evaluate the outcomes and prognostic factors in children with extracranial germ cell tumors (GCTs) treated at a single institution.MethodsSixty-six children diagnosed with extracranial GCTs between 1996 and 2012 were included in the study. Primary treatment was surgical excision, followed by six cycles of cisplatin-based chemotherapy. The survival rates were compared according to the International Germ Cell Cancer Cooperative Group classification used for GCTs in adults to validate the classification guidelines for GCTs in children.ResultsThe median patient age was 4.4 years. In 34 patients (51.5%), the primary tumor site was the gonad. Extragonadal GCTs were detected in 32 patients. The 5-year overall survival and event-free survival (EFS) were 92.0%±3.5% and 90.4%±3.7%, respectively. In univariate analysis, tumor histology, metastasis, and elevated alpha-fetoprotein were not prognostic factors in children with extracranial GCTs. However, EFS was poorer in patients with mediastinal disease (n=12, 66.7%±13.6 %) than in those with nonmediastinal disease (n=54, 96.0%±2.8%) (P=0.001). The 5-year EFS was lower in patients older than 10 years, (n=21, 80.0%±8.9%) compared with those younger than 10 years (n=45, 95.2%±3.3%) (P=0.04). Multivariate analysis identified the mediastinal tumor site as the only independent prognostic factor.ConclusionThe prognosis of children with extracranial GCTs was favorable. However, nongerminomatous mediastinal tumors were associated with poor survival in children. Further research is needed to improve the prognosis of children with malignant mediastinal GCTs

Unsupervised Machine Learning Using K-Means Identifies Radiomic Subgroups of Pediatric Low-Grade Gliomas That Correlate With Key Molecular Markers

Introduction: Despite advancements in molecular and histopathologic characterization of pediatric low-grade gliomas (pLGGs), there remains significant phenotypic heterogeneity among tumors with similar categorizations. We hypothesized that an unsupervised machine learning approach based on radiomic features may reveal distinct pLGG imaging subtypes. Methods: Multi-parametric MR images (T1 pre- and post-contrast, T2, and T2 FLAIR) from 157 patients with pLGGs were collected and 881 quantitative radiomic features were extracted from tumorous region. Clustering was performed using K-means after applying principal component analysis (PCA) for feature dimensionality reduction. Molecular and demographic data was obtained from the PedCBioportal and compared between imaging subtypes. Results: K-means identified three distinct imaging-based subtypes. Subtypes differed in mutational frequencies of BRAF (p \u3c 0.05) as well as the gene expression of BRAF (p\u3c0.05). It was also found that age (p \u3c 0.05), tumor location (p \u3c 0.01), and tumor histology (p \u3c 0.0001) differed significantly between the imaging subtypes. Conclusion: In this exploratory work, it was found that clustering of pLGGs based on radiomic features identifies distinct, imaging-based subtypes that correlate with important molecular markers and demographic details. This finding supports the notion that incorporation of radiomic data could augment our ability to better characterize pLGGs

Clustered housing cycles

Using a panel of U.S. city-level building permits data, we estimate a Markov-switching model of housing cycles that allows cities to systematically deviate from the national housing cycle. These deviations occur for clusters of cities that experience simultaneous housing contractions. We find that cities do not form housing regions in the traditional geographic sense. Instead, similarities in factors affecting the demand for housing (such as population growth or availability of credit) appear to be more important determinants of cyclical co-movements than similarities in factors affecting the supply for land (such as the availability of developable land or the elasticity of land supply)