Small-Scale Discharges Observed Near the Top of a Thunderstorm

We have used the LOw-Frequency ARray (LOFAR) to image a few lightning flashes during a particularly severe thunderstorm. The images show an exceptional amount of VHF activity at altitudes above 10 km. Much of this is in the form of small-scale discharges, not exceeding a few hundred meter, occurring seemingly randomly around the centers of active storm cells. To emphasize the incidental nature of these small-scale discharges or sparks we refer to them as “sparkles.” A detailed investigation shows evidence that these sparkles are indicative of positive leader channels and that they are equivalent to the needle activity seen around positive leader tracks at lower altitudes.</p

Trauma mechanism and patient reported outcome in tibial plateau fractures with posterior involvement

Introduction: Posterior tibial plateau fractures (PTPF) have a high impact on functional outcome and the optimal treatment strategy is not well established. The goal of this study was to assess the relationship between trauma mechanism, fracture morphology and functional outcome in a large multicenter cohort and define possible strategies to improve the outcome. Methods: An international retrospective cohort study was conducted in five level-1 trauma centers. All consecutive operatively treated PTPF were evaluated. Preoperative imaging was reviewed to determine the trauma mechanism. Patient reported outcome was scored using the Knee injury and Osteoarthritis Outcome Score (KOOS). Results: A total of 145 tibial plateau fractures with posterior involvement were selected with a median follow-up of 32.2 months (IQR 24.1-43.2). Nine patients (6%) sustained an isolated posterior fracture. Seventy-two patients (49%) sustained a two-column fracture and three-column fractures were diagnosed in 64 (44%) patients. Varus trauma was associated with poorer outcome on the 'symptoms' (p = 0.004) and 'pain' subscales (p = 0.039). Delayed-staged surgery was associated with worse outcome scores for all subscales except 'pain'. In total, 27 patients (18%) were treated with posterior plate osteosynthesis without any significant difference in outcome. Conclusions: Fracture morphology, varus trauma mechanism and delayed-staged surgery (i.e. extensive soft-tissue injury) were identified as important prognostic factors on postoperative outcome in PTPF. In order to assess possible improvement of outcome, future studies with routine preoperative MRI to assess associated ligamentous injury in tibial plateau fractures (especially for varus trauma) are needed. (c) 2021 Elsevier B.V. All rights reserved

Dialkylenecarbonate-Bridged Polysilsesquioxanes: Hybrid Organic-Inorganic Sol-Gels with a Thermally Labile Bridging Group

In this paper, we introduce a new approach for altering the properties of bridged polysilsesquioxane xerogels using post-processing modification of the polymeric network. The bridging organic group contains latent functionalities that can be liberated thermally, photochemically, or by chemical means after the gel has been processed to a xerogel. These modifications can produce changes in density, volubility, porosity, and or chemical properties of the material. Since every monomer possesses two latent functional groups, the technique allows for the introduction of high levels of functionality in hybrid organic-inorganic materials. Dialkylenecarbonate-bridged polysilsesquioxane gels were prepared by the sol-gel polymerization of bis(triethoxysilylpropyl)carbonate (1) and bis(triethoxysilylisobutyl)-carbonate (2). Thermal treatment of the resulting non-porous xerogels and aerogels at 300-350 C resulted in quantitative decarboxylation of the dialkylenecarbonate bridging groups to give new hydroxyalkyl and olefinic substituted polysilsesquioxane monolithic xerogels and aerogels that can not be directly prepared through direct sol-gel polymerization of organotrialkoxysilanes

Accuracy of Patient-Specific Drilling Guides in Acetabular Fracture Surgery:A Human Cadaver Study

Due to the complex anatomical shape of the pelvis, screw placement can be challenging in acetabular fracture surgery. This study aims to assess the accuracy of screw placement using patient-specific surgical drilling guides applied to pre-contoured conventional implants in acetabular fracture surgery. CT scans were made of four human cadavers to create 3D models of each (unfractured) pelvis. Implants were pre-contoured on 3D printed pelvic models and optically scanned. Following virtual preoperative planning, surgical drilling guides were designed to fit on top of the implant and were 3D printed. The differences between the pre-planned and actual screw directions (degrees) and screw entry points (mm) were assessed from the pre- and postoperative CT-scans. The median difference between the planned and actual screw direction was 5.9° (IQR: 4–8°) for the in-plate screws and 7.6° (IQR: 6–10°) for the infra-acetabular and column screws. The median entry point differences were 3.6 (IQR: 2–5) mm for the in-plate screws and 2.6 (IQR: 2–3) mm for the infra-acetabular and column screws. No screws penetrated into the hip joint or caused soft tissue injuries. Three-dimensional preoperative planning in combination with surgical guides that envelope pre-contoured conventional implants result in accurate screw placement during acetabular fracture surgery

Does 3D-assisted surgery of tibial plateau fractures improve surgical and patient outcome?:A systematic review of 1074 patients

PURPOSE: The aim of this systematic review was to provide an overview of current applications of 3D technologies in surgical management of tibial plateau fractures and to assess whether 3D-assisted surgery results in improved clinical outcome as compared to surgery based on conventional imaging modalities. METHODS: A literature search was performed in Pubmed and Embase for articles reporting on the use of 3D techniques in operative management of tibial plateau fractures. This systematic review was performed in concordance with the PRISMA-guidelines. Methodological quality and risk of bias was assessed according to the guidelines of the McMaster Critical Appraisal. Differences in terms of operation time, blood loss, fluoroscopy frequency, intra-operative revision rates and patient-reported outcomes between 3D-assisted and conventional surgery were assessed. Data were pooled using the inverse variance weighting method in RevMan. RESULTS: Twenty articles evaluating 948 patients treated with 3D-assisted surgery and 126 patients with conventional surgery were included. Five different concepts of 3D-assisted surgery were identified: '3D virtual visualization', '3D printed hand-held fracture models', 'Pre-contouring of osteosynthesis plates', '3D printed surgical guides', and 'Intra-operative 3D imaging'. 3D-assisted surgery resulted in reduced operation time (104.7 vs. 126.4 min; P < 0.01), less blood loss (241 ml vs. 306 ml; P < 0.01), decreased frequency of fluoroscopy (5.8 vs. 9.1 times; P < 0.01). No differences in functional outcome was found (Hospital for Special Surgery Knee-Rating Scale: 88.6 vs. 82.8; P = 0.23). CONCLUSIONS: Five concepts of 3D-assisted surgical management of tibial plateau fractures emerged over the last decade. These include 3D virtual fracture visualization, 3D-printed hand-held fracture models for surgical planning, 3D-printed models for pre-contouring of osteosynthesis plates, 3D-printed surgical guides, and intra-operative 3D imaging. 3D-assisted surgery may have a positive effect on operation time, blood loss, and fluoroscopy frequency

Portraits of life: Patterns of events over the lifespan

This explorative content-analytic study completes earlier studies on the lifespan distributions of number and affect of past and future life-events, collected by means of the Life-line Interview Method (LIM), for three age groups of men and women (young, middle and late adulthood). LIM events were classified into 40 subcategories divided over 9 categories: Relations, School, Work, Health, Growth, Home, Birth, Death and Other. Compression of the full data set by age group, gender, affect, decade, and time perspective, disclosed various patterns of events underlying the human life-course, e.g., the ‘bump,’ ‘rosy view’ and ‘gender phase contrast’ patterns. The compressed data set provided detailed material for the composition of three written group portraits of life, reflecting the modal life story of young, middle-aged and older men and women. Patterns and portraits show a content shift of past memories and future expectations over the lifespan, supporting a more dynamic view on the human life-course

Current-induced highly dissipative domains in high Tc thin films

We have investigated the resistive response of high Tc thin films submitted to a high density of current. For this purpose, current pulses were applied into bridges made of Nd(1.15)Ba(1.85)Cu3O7 and Bi2Sr2CaCu2O8. By recording the time dependent voltage, we observe that at a certain critical current j*, a highly dissipative domain develops somewhere along the bridge. The successive formation of these domains produces stepped I-V characteristics. We present evidences that these domains are not regions with a temperature above Tc, as for hot spots. In fact this phenomenon appears to be analog to the nucleation of phase-slip centers observed in conventional superconductors near Tc, but here in contrast they appear in a wide temperature range. Under some conditions, these domains will propagate and destroy the superconductivity within the whole sample. We have measured the temperature dependence of j* and found a similar behavior in the two investigated compounds. This temperature dependence is just the one expected for the depairing current, but the amplitude is about 100 times smaller.Comment: 9 pages, 9 figures, Revtex, to appear in Phys. Rev.

Quantitative 3D measurements of tibial plateau fractures

Fracture gap and step-off measurements on 2DCT-slices probably underestimate the complex multi-directional features of tibial plateau fractures. Our aim was to develop a quantitative 3D-CT (Q3DCT) fracture analysis of these injuries. CT-based 3D models were created for 10 patients with a tibial plateau fracture. Several 3D measures (gap area, articular surface involvement, 3D displacement) were developed and tested. Gaps and step-offs were measured in 2D and 3D. All measurements were repeated by six observers and the reproducibility was determined by intra-class correlation coefficients. Q3DCT measurements demonstrated a median gap of 5.3 mm, step-off of 5.2 mm, gap area of 235 mm2, articular surface involvement of 33% and 3D displacement of 6.1 mm. The inter-rater reliability was higher in the Q3DCT than in the 2DCT measurements for both the gap (0.96 vs. 0.81) and step-off (0.63 vs. 0.32). Q3DCT measurements showed excellent reliability (ICC of 0.94 for gap area, 1 for articular surface involvement and 0.99 for 3D displacement). Q3DCT fracture analysis of tibial plateau fractures is feasible and shows excellent reliability. 3D measurements could be used together with the current classification systems to quantify the true extent of these complex multi-directional fractures in a standardized way

Successful management of an aortoesophageal fistula caused by a fish bone – case report and review of literature

We report a case of aortoesophageal fistula (AEF) caused by a fish bone that had a successful outcome. Aortoesophageal fistula is a rare complication of foreign body ingestion from which few patients survive. Over one hundred cases of AEF secondary to foreign body ingestion have been documented but only seven, including our case, have survived over 12 months. Treatment involved stabilising the patient with a Sengstaken-Blakemore tube and insertion of a thoracic aortic endovascular stent-graft. Unfortunately the stent became infected and definitive open surgical repair involved removing the stent, replacing the aorta with a homograft and coverage with a left trapezius flap while under deep hypothermic arrest