Navigation Research Articles

From Relation Algebra to Semi-join Algebra: An Approach to Graph Query Optimization

Abstract Many graph query languages rely on composition to navigate graphs and select nodes of interest, even though evaluating compositions of relations can be costly. Often, this need for composition can be reduced by rewriting toward queries using semi-joins instead, resulting in a significant reduction of the query evaluation cost. We study techniques to recognize and apply such rewritings. Concretely, we study the relationship between the expressive power of the relation algebras, which heavily rely on composition, and the semi-join algebras, which replace composition in favor of semi-joins. Our main result is that each fragment of the relation algebras where intersection and/or difference is only used on edges (and not on complex compositions) is expressively equivalent to a fragment of the semi-join algebras. This expressive equivalence holds for node queries evaluating to sets of nodes. For practical relevance, we exhibit constructive rules for rewriting relation algebra queries to semi-join algebra queries and prove that they lead to only a well-bounded increase in the number of steps needed to evaluate the rewritten queries. In addition, on sibling-ordered trees, we establish new relationships among the expressive power of Regular XPath, Conditional XPath, FO-logic and the semi-join algebra augmented with restricted fixpoint operators.

A Study on the Seaborne Collision Avoidance System Using the Airborne CAS

Mankind has been using ships for more than 5,000 years and has developed a range of related technologies. However, despite such a long history, compared to aircraft with a history of approximately one century, the pace of progress has been markedly slow. Even though technological progress of ships or the installation of various navigation equipment have been achieved, seaborne collisions have occurred quite frequently. This study analyzed the TCAS( Traffic Collision Avoidance System) that has contributed to the prevention of collisions with other transport methods including aircraft to suggest a collision avoidance system that can be deployed for ships. To apply the technologies applied to aircraft that move in 3D to ships that move in 2D, the difference in the operational environment between the two modes was analyzed to identify elements that need to be applied to ships. The suggested display of data on the collision prevention system is one that manipulates the augmented reality display device used in automobiles that over the past few years has undergone rapid development. Based on the presentation of technological elements that need to be considered when adopting the SCAS or the Seaborne Collision Avoidance System as suggested in this study, the authors hope to contribute to the prevention of collisions.

Élaboration d'un énoncé de position national sur la navigation des patients atteints de cancer au Canada.

Au Canada, le paysage des soins du cancer évolue et les infirmières en oncologie sont appelées à jouer de nouveaux rôles afin d'améliorer l'expérience des patients et des familles et de répondre à leurs besoins toujours changeants. L'un de ces rôles, la navigation des patients atteints de cancer (NPC), vise principalement à coordonner les soins centrés sur la personne et à guider les patients dans le système de santé. Dans plusieurs provinces et territoires du Canada, la navigation est devenue essentielle pour offrir des soins de grande qualité aux patients cancéreux. Depuis 2016, des chefs de file des soins infirmiers oncologiques se réunissent au sein d'un groupe national pour synthétiser leur compréhension de la navigation des patients en contexte canadien afin d'élaborer un énoncé de position national sur la NPC. Dans le présent article, nous analyserons l'historique de l'élaboration de l'énoncé de position sur la NPC que publiera prochainement l'Association canadienne des infirmières en oncologie (ACIO/CANO). Nous analyserons également les commentaires des participants aux ateliers tenus dans le cadre des congrès de 2016, 2017 et 2018, de même que les comptes rendus des réunions du groupe de travail national qui ont eu lieu pendant cette même période. Le présent article se veut un sommaire historique concis de l'évolution de la NPC au Canada, ainsi qu'un modèle pour les autres groupes aspirant à rédiger un énoncé de position consensuel.

Estimation of Optimal Empirical Equations based on Sediments of Ageing Reservoir Estimated Using Autonomous Navigation USV

Estimation of Optimal Empirical Equations based on Sediments of Ageing Reservoir Estimated Using Autonomous Navigation USV

Design and experiment of a high-clearance self-propelled sprayer chassis

A large high-clearance self-propelled sprayer chassis was designed according to the requirements of the sprayer’s driving operation and the overall goal. The structural characteristics and working principle of the chassis drive system, suspension system, track adjustment system, and frame were analyzed. A finite element analysis of the frame was carried out under four extreme conditions: full load bending, full load torsion, full load emergency braking and full load emergency turning. Under these four conditions, the maximum stress values of the frame were 149.45 MPa, 219 MPa, 151.44 MPa, and 123.27 MPa respectively, and the maximum strain values were 1.12 mm, 2.22 mm, 0.95 mm, and 1.16 mm respectively. A theoretical analysis of the stability, steering ability, and obstacle navigation of the sprayer chassis was conducted. The results showed that the upper angle θlim, lower angle θ׳lim and lateral limit tumbling angle φlim of the sprayer chassis were 50.1°, 30.0° and 35.3° respectively. The minimum turning radius of the chassis was 5816 mm, and the minimum turning width was 4113 mm. The maximum obstacle crossing heights of the front and rear wheels were 466 mm and 457 mm. The theoretical analysis showed that the designed chassis met the field management operations of large plots. A field experiment of the high-clearance self-propelled sprayer chassis at full load was conducted. The experimental results were consistent with the theoretical analysis results. The sprayer chassis not only good handling stability but also good ride comfort. The results of this study provide references for the design of high-clearance self-propelled sprayer chassis. Keywords: high-clearance self-propelled sprayer, chassis performance, frame, suspension, design, experiment DOI: 10.25165/j.ijabe.20201302.5262 Citation: Chen Y, Mao E R, Li W, Zhang S, Song Z H, Yang S J, et al. Design and experiment of a high-clearance self-propelled sprayer chassis. Int J Agric & Biol Eng, 2020; 13(2): 71–80.

GOES-R series image navigation and registration performance assessment tool set

An image navigation (NAV) and registration (INR) performance assessment tool set (IPATS) was developed to assess the US Geostationary Operational Environmental Satellite R-series (GOES-R) Advanced Baseline Imager (ABI) and Geostationary Lightning Mapper (GLM) INR performance. IPATS produces five INR metrics for level 1B ABI images: navigation, channel-to-channel registration, frame-to-frame registration, swath-to-swath registration, and within-frame registration. IPATS also produces one INR metric for GLM: navigation of background images. The high-precision INR metrics produced by IPATS are critical to INR performance evaluation and long-term monitoring. IPATS INR metrics also provide feedback to INR engineers for tuning the navigation algorithms and parameters to further refine INR performance. IPATS utilizes a modular algorithm design to allow the user-selectable data processing sequence and configuration parameters. We first describe the algorithmic design and the implementation of IPATS. Next, it describes the investigation of the optimization of the configuration parameters to reduce measurement errors. Finally, sample INR performance is presented, including GOES-16 and GOES-17 ABI NAV performance from postlaunch test to November 2019 and the comparison of example 24-h INR performance against the mission performance requirements. The INR assessment results show that both GOES-R ABIs are in compliance with the mission INR requirements.

Six Ways to Help Users More Easily Navigate Your Website

Six Ways to Help Users More Easily Navigate Your Website

Application of neuronavigation combined with yellow fluorescence staining in the resection of supratentorial glioma

Objective To explore the application of neuronavigation combined with yellow fluorescence staining in the operation of glioma. Methods A retrospective study was conducted on the clinical data of 172 patients with supratentorial glioma who underwent surgical treatment at Department of Neurosurgery, Zhongnan Hospital of Wuhan University from January 2016 to March 2018. Among them, 55 cases were treated with neuronavigation combined with yellow fluorescence staining (navigation + fluorescence group) and 117 cases with conventional surgical techniques (control group). There were 81 patients with tumors involving the eloquent area, and neuroelectrophysiological monitoring and/or intraoperative awake anesthesia were applied in all those patients. Total resection rate was compared between the 2 groups to analyze the factors influencing the total resection rate. Results Total resection was performed in 58 patients confirmed by postoperative imaging. The total resection rate was 45.5%(25/55) in group of neuronavigation + fluorescence and 28.2%(33/117) in the control group. There was statistically significant difference between the 2 groups(P=0.026). Multiple logistic regression analysis revealed that involvement of eloquent area (OR=0.502, 95% CI: 0.253-0.998, P=0.049) and the technique of neuronavigation plus fluorescence (OR=2.173, 95% CI: 1.080-4.371, P=0.030) were independent prognostic factors of the total resection for glioma. Among the 81 patients involving the eloquent area, total resection was achieved in 21 patients(25.9%), of whom 13(61.9%) were treated with fluorescence combined with neuronavigation. Incomplete resection was achieved in 60 patients, of whom 16(26.7%) were treated with fluorescence combined with neuronavigation. There was statistically significant difference between the 2 groups (P=0.004). Multiple logistic regression analysis revealed that the technique of neuronavigation combined with fluorescence (OR=3.896, 95% CI: 1.331-11.405, P=0.013) were independent prognostic factors of total resection. Conclusion Neuronavigation combined with yellow fluorescence staining can be helpful in the total resection of glioma . Key words: Glioma; Neuronavigation; Fluorescence staining; Neurosurgical procedures; Extent of resection

Study on diagnostic performance of fetal intelligent navigation echocardiography for congenital heart defect

Objective To explore the sensitivity and specificity of fetal intelligent navigation echocardiography(FINE, 5D Heart) in the prenatal detection of congenital heart defect(CHD), and to compare its diagnostic performance with spatiotemporal image correlation(STIC) loop (STICloop). Methods A total of 250 pregnant women having a singleton pregnancy in the second and third trimesters from April 2018 to May 2019 in Sir Run Run Shaw Hospital, Zhejiang University College of Medicine were enrolled in this prospective study. 2D ultrasound diagnosis has been made before acquiring STIC volume data set. After the appropriateness of each volume data set was preliminarily determined, all identifying informations were concealed and the appropriate volumes were randomly distributed to less experienced sonographer for analysis using 5D Heart software. The sensitivity and specificity, positive and negative likelihood ratios, as well as area under the receiver operating characteristic curve (AUC) of the two methods were determined respectively, and the differences between the two methods were statistically analyzed. Results The diagnostic performance of 5D Heart for the prenatal detection of CHD was: sensitivity of 95.45% (105/110), specificity of 94.29% (132/140), positive likelihood ratio of 16.72, negative likelihood ratio of 0.05, and AUC of 0.95, respectively. Among cases with confirmed CHD, the 5D Heart diagnosis completely matched the final diagnosis in 77.27% (85/110). The diagnostic performance of STICloop for the prenatal detection of CHD was: sensitivity of 90.91% (100/110), specificity of 92.86% (130/140), positive likelihood ratio of 12.73, negative likelihood ratio of 0.10, and AUC of 0.92. The sensitivity and secificity of 5D Heart in diagnosing CHD were both higher than 90%, and it could successfully detect a broad spectrum of severe fetal CHD. Among cases with confirmed CHD, even the STICloop diagnosis completely matched the final diagnosis in 61.81%(68/110), its diagnostic accuracy was relatively lower than 5D Heart (P=0.013). However, there were no statistical differences between the two methods in sensitivity and specificity(all P>0.05). Conclusions The sesitivity and specifity of 5D Heart in diagnosis CHD were both higher than 90%, and it could successfully detect a broad spectrum of severe fetal CHD. STICloop could be used for preliminary screening of CHD, as it has the same high sensitivity and specificity as 5D Heart. Further examination may be recommended when fetal heart abnormalities are suspected. Key words: Echocardiography; Congenital heart defect; Fetal intelligent navigation echocardiography; Spatiotemporal image correlation

Application of computer aided design 3D printed navigation template in Salter pelvic osteotomy for dislocation of hip joint in children

Objective To explore the feasibility of accurate localization for the acetabular direction in Salter pelvic osteotomy for the developmental dislocation of the hip joint in children by using computer aided design and 3D printing technique. Methods The clinical data of 12 patients of unilateral hip dislocation treated with Salter pelvic osteotomy by using 3D printed navigation template in Department of Orthopedics, Children′s Hospital of Nanjing Medical University From October 2016 to April 2017 were retrospectively analyzed.Among the 12 cases, there were 4 males and 8 females, 5 hips on the left and 7 hips on the right, aged 1.5 to 5.0 years old (mean 2.3 years old). According to the CT data, the models of the healthy hip joint were mirrored to the contralateral side by Mimics software.Computer-aided simulations of Salter pelvic osteotomy on models of the affected hip joints were performed.Then, the models of the affec-ted hip joint were rotated to the mirror models of the contralateral hip joint.The navigation templates were designed according to the exposed pelvic surface morphology during the operation.The navigation templates were printed by rapid prototyping technology to guide the operation.Preoperative and postoperative acetabular index (AI) and center edge angle (CEA) of affected side were compared to postoperative AI and CEA of contralateral side respectively. Results A method of making personalized navigation templates for Salter pelvic osteotomy was established in 12 children with developmental dislocation of the hip joint.The operation time ranged from 40.2 to 64.5 min, averaging (50.6±8.5) min.The intraoperative bleeding volume ranged from 35 to 60 mL, averaging 52 mL.No vascular and nerve injury was found in the postoperative examination, and no child had complications such as infection, residual foreign body of the guide plate and so on.There was significant difference in preoperative measurements regarding AI between the affected side [(38.4±2.8)°] and the contralateral side [(21.6±0.8)°](t=-18.77, P 0.05), there was no significant difference in postoperative measurements regarding CEA between the affected side[(21.2±2.6)°] and the contralateral side(t=-0.435, P>0.05). Conclusions The navigation template prepared by computer aided design and 3D printing technology has good accuracy, and is a new approach to accurate acetabular rotation in children with the developmental dislocation of the hip joint for Salter pelvic osteotomy. Key words: Dislocation of hip joint; Osteotomy; 3D printing

Review of Cultural Studies of Disability in Education: Interdisciplinary Navigations of the Normative Divide by David Bolt

No abstract available.

The ultrasonic navigation technique in percutaneous transhepatic one-step biliary fistulation with rigid cholangioscopic lithotripsy for complicated hepatolithiasis

Objective To study the efficacy and safety of percutaneous transhepatic one-step biliary fistulation (PTOBF) with rigid cholangioscopic lithotripsy for treatment of complicated hepatolithiasis under the ultrasonic navigation technique. Methods In this retrospective study, PTOBF lithotripsy surgery was performed in 94 patients with hepatolithiasis under general anesthesia with tracheal intubation, and with percutaneous transhepatic puncture of targeted bile duct under ultrasonic navigation in The First Affiliated Hospital of Guangzhou Medical University. Biliary expanders were used along a guidewire to expand the sinus gradually until 14Fr to establish a fistulous channel. Lithotripsy was then performed through the channel by rigid cholangioscopy. The operation-related data were collected and analyzed, including puncture and fistula establishment success ratio, complication rate, intraoperative blood loss, residual and recurrence hepatolithiasis rates. Results 94 patients (total 122 patient-times) underwent PTOBF lithotripsy. There was no perioperative mortality. The overall puncture success rate was 100%, and the fistula/puncture rate was 97.5% (119/122). In 118 patients success was achieved in 2 time (96.7%). The complication rate was 9.6% (9/94). The average intraoperation blood loss were (24.9±21.3)ml. The residual calculus rate after therapy was 13.8%(13/94). All patients were followed-up for a period that ranged between 18 and 30 months. The recurrence rate was 14.9%(14/94). Conclusions Ultrasonic navigation technique plays an important role in bile duct puncture, sinus expansion and rigid cholangioscopic lithotripsy for treatment of complicated hepatolithiasis. PTOBF lithotripsy is a safe and effective procedure, which provides a new way in mini-invasive treatment for hepatolithiasis. It is worth generalizing. Key words: Ultrasound; Navigation; Percutaneous transhepatic puncture; Hepatolithiasis; Rigid cholangioscope

Model of generating grid cell based on difference Hebbian learning in brain-inspired navigation

Model of generating grid cell based on difference Hebbian learning in brain-inspired navigation

Intraoperative Navigation and Cone Beam Computed Tomography for Restoring Orbital Dimensions: A Single-Center Experience.

Correction of post-traumatic orbital defects remains a challenge for the maxillofacial surgeon. We examined the added value of combined intraoperative (IO) navigation and IO cone beam computed tomography (CBCT). A retrospective cohort study was performed in all consecutive patients requiring unilateral post-traumatic orbital surgery between January 2012 and December 2018. Patients were divided into 3 groups: IO navigation (NAV), IO-CBCT (CBCT), and IO navigation with IO-CBCT (NAV-CBCT). A detailed description of our workflow is provided. Volumetric comparison of the operated orbit to the contralateral orbit was made with Brainlab. Of the 81 cases, 22 patients were included (12 males/10 females) with a mean age of 51 years. Three patients were assigned to NAV, 6 to CBCT, and 13 to NAV-CBCT. The reconstructed orbital volume did not significantly differ from the contralateral orbital volume within the 3 groups. The mean difference between the contralateral and the operated orbit was 3.05 cm3, 3.72 cm3, and 1.47 cm3 for NAV, CBCT, and NAV-CBCT, respectively, where only NAV-CBCT showed a significant smaller volumetric difference in comparison to CBCT alone. Gender or age did not correlate with difference in orbital volume. Normal function and aesthetics was seen at 6 weeks postoperative in 0 of 3, 6of 6, and 6 of 13 patients of the NAV, CBCT, and NAV-CBCT, respectively. Orbital defects can be treated effectively using IO navigation. Although our data could not demonstrate a significant added value of IO-CBCT in cases where IO navigation was used based on volumetric difference alone, the combination of IO-CBCT and IO navigation seems to give the best results considering both volumetric difference and postoperative function and aesthetics. Confirmation in a prospective, randomized trial with a larger sample size is required.

Application of holographic image navigation in urological laparoscopic and robotic surgery

Objective To evaluate the clinical value of holographic image navigation in urological laparoscopic and robotic surgery. Methods The data of patients were reviewed retrospectively for whom accepted holographic image navigation laparoscopic and robotic surgery from Jan. 2019 to Dec. 2019 in Beijing United Family Hospital and other 18 medical centers, including 78 cases of renal tumor, 2 cases of bladder cancer, 2 cases of adrenal gland tumor, 1 cases of renal cyst, 1 case of prostate cancer, 1 case of sweat gland carcinoma with lymph node metastasis, 1 case of pelvic metastasis after radical cystectomy. All the patients underwent operations. In the laparoscopic surgery group, there were 27 cases of partial nephrectomy, 1 case of radical prostatectomy, 2 cases of radical cystectomy and 2 cases of adrenalectomy. In the da Vinci robotic surgery group of 54 cases, there were 51 cases of partial nephrectomy, 1 case of retroperitoneal lymph node dissection, 1 case of retroperitoneal bilateral renal cyst deroofing and 1 case of resection of pelvic metastasis. There were 41 partial nephrectomy patients with available clinical data for statistic, with a median age of 53.5 years (range 24-76), including 26 males and 15 females. The median R. E.N.A.L score was 7.8 (range 4-11). Before the operation, the engineers established the holographic image based on the contrast CT images and reports. The surgeon applied the holographic image for preoperative planning. During the operation, the navigation was achieved by real time fusing holographic images with the laparoscopic surgery images in the screen. Results All the procedures had been complete uneventfully. The holographic images helped surgeon in understanding the visual three- dimension structure and relation of vessels supplying tumor or resection tissue, lymph nodes and nerves. By manipulating the holographic images extracorporeally, the fused image guide surgeons about location vessel, lymph node and other important structure and then facilitate the delicate dissection. For the 41 cases with available clinical data including 23 cases of robotic-assisted partial nephrectomy and 18 cases of laparoscopic nephrectomy, the median operation time was 140(range 50-225)min, the median warm ischemia time was 23(range 14-60)min, the median blood loss was 80(range 5-1 200)ml. In the robotic surgery group, the median operation time was 140(range 50-215)min, the median warm ischemia time was 21(range 17-40)min, the median blood loss was 150(range 30-1 200)ml. In the laparoscopic surgery group, the median operation time was 160(range 80-225)min, the median warm ischemia time was 25(range 14-60)min, the median blood loss was 50(range 5-1 200)ml. All the patients had no adjacent organ injury during operation. There were 2 cases with Clavien Ⅱcomplications. One required transfusion and the other one suffered hematoma post-operation. However, the tumors were located in the renal hilus for these 2 cases and the R. E.N.A.L scores were both 11. Conclusions Holographic image navigation can help location and recognize important anatomic structures during the surgical procedures.. This technique will reduce the tissue injury, decrease the complications and improve the success rate of surgery. Key words: Laparoscopic; 3 dimension image reconstruction; Holographic Imaging; Laparoscopic surgery; Robotic surgery

Synthesis of one-stage signal processing algorithm for space radio navigation receiver

High requirements are imposed on modern user navigation apparatuses (UNA) of global navigation satellite systems (GNSS) in terms of the navigation support accuracy. As a rule, the UNA is built according to the scheme with two-stage signal processing. At the first stage, navigation signals are received and transferred to the intermediate frequency, signals are searched for and tracking of signal parameters (delay, phase, Doppler frequency shift) is performed. At the second stage, pseudo-ranges, pseudo-phases and pseudo-Doppler frequencies are measured, digital information is selected from the received radio signals and the navigation problem is solved, i.e. the coordinates and components of the user’s velocity vector are determined. The use of one-stage processing of navigation signals is one of the promising areas for further improving the navigational sighting accuracy in a UNA. In this case, all signals are processed in a single integrated filter with simultaneous solution of the navigation task. The article considers the synthesis of an optimal one-stage algorithm for processing GNSS signals using the theory of optimal filtering. This synthesis is aimed at providing the best accuracy in estimating the coordinates and components of the user’s velocity vector. The final algorithm implements vector tracking for the delays in received signals and their phases. Vector tracking loop includes a standard set of correlators, delay and phase discriminators and an integrated filter of the augmented state vector.

Application of electromagnetic navigation in orthopedics diagnosis and treatment

To summarize the current application of electromagnetic navigation in orthopedics, summarize its characteristics, and provide a better basis for clinical treatment.The domestic and foreign literatures on the application of electromagnetic navigation in orthopedics were reviewed and summarized.Various navigation systems have been used in various clinical fields.Among them, electromagnetic navigation systems have become more and more widely used in orthopedics, and their status has become increasingly prominent.There are many navigation and positioning technologies, which should be comprehensively selected according to the actual clinical situation.Electromagnetic navigation has relatively obvious advantages and greater development potential, and still needs a lot of clinical research to verify. Key words: Electromagnetic navigation; Joint orthopedics; Spine surgery; Trauma orthopedics

Comparative study of posterior minimally invasive plate and 3D-navigated percutaneous sacroiliac screw internal fixation for treatment of posterior pelvic ring fracture in elderly patients

Objective To compare the clinical efficacy of posterior minimally invasive reconstruction plate and 3D-navigated percutaneous sacroiliac screw fixation of elderly patients with posterior pelvic ring fractures. Methods A retrospective cases control study was performed to analyze the data of 75 elderly patients with posterior pelvic ring fractures admitted from January 2014 to June 2018 in Central Hospital of the PLA. There were 32 males and 43 females, with the age range of 60-83 years (mean, 67.7 years). Twenty-four patients in the plate group were treated by posterior minimally invasive reconstruction plate fixation, and 51 patients in the navigation group were treated by percutaneous sacroiliac screw internal fixation with 3D navigation. The operation time, intraoperative blood loss, X-ray exposure time, complication rate and postoperative visual analogue scale (VAS) were compared between the two groups. Postoperative Matta radiographic criteria was used to assess fracture reduction quality, and Majeed criteria was used to assess pelvic function at the last follow-up. Results All 75 patients were followed up for 6-24 months (mean, 13.5 months). The operation time, intraoperative blood loss and X-ray exposure time in the plate group were (126.1±20.6)minutes, (251.6±50.8)ml, and (15.7±4.4)s, showing significant differences in comparison with the navigation groups [(49.7±17.5)minutes, (22.8±5.1)ml, and (112.8±8.8)s](P 0.05). At day 3, one week, and one month postoperatively, the VAS in the navigation group was (3.3±0.7)points, (3.2±0.7)points, (2.4±0.6)points, better than that in the plate group [(7.2±0.7)points, (6.2±0.8)points and (4.5±0.7)points] (P 0.05). According to the Matta radiographic criteria, the excellent and good rate was 92% in plate group (excellent in 14 cases, good in 8, and fair in 2), and was 82% in the navigation group (excellent in 25 cases, good in 17 and fair in 9). There was no significant difference between the two groups (P>0.05). According to the Majeed criteria at the follow-up, the excellent and good rate was 96% in the plate group (excellent in 15 cases, good in 8 and fair in 1), and was 94% in the navigation group (excellent in 35 cases, good in 13 and fair in 3). The difference between the two groups was not statistically significant (P>0.05). Conclusion For elderly patients with osteoporotic posterior pelvic ring fractures, percutaneous sacroiliac screw fixation under 3D navigation has the advantages of shorter operation time, less bleeding, less radiation dose and less postoperative pain than minimally invasive reconstruction plate internal fixation, and hence deserves clinical application. Key words: Aged; Pelvis; Fracture fixation, internal; Osteoporosis; Surgery, computer aided

A suicide prevention strategy for youth presenting to the emergency department with suicide related behaviour: protocol for a randomized controlled trial

BackgroundSuicide is a leading cause of death among adolescents in North America. Youth who present to the Emergency Department (ED) with acute suicidality are at increased risk for eventual death by suicide, thereby presenting an opportunity for secondary prevention of suicide. The current study evaluates the effectiveness of a standardized individual and family-based suicidal behaviour risk reduction intervention targeting adolescents at high-risk for suicide.MethodsA randomized controlled trial (RCT) will be conducted to evaluate the effectiveness of a manualized youth- and family- based suicide prevention strategy (SPS) as compared with case navigation (NAV) among adolescents aged 12 to 18 years of age who present to the ED with acute suicidal ideation (SI) or suicide risk behaviours (SRB). We will recruit 128 participants and compare psychiatric symptoms including SI/SRB, family communication, and functional impairment at baseline and follow-ups (post-intervention [6 weeks], 24 weeks). The primary outcome is change in suicidal ideation measured with the Suicide Ideation Questionnaire- Junior. SRBs are measured with the Suicide Behaviour Questionnaire. Secondary outcomes are change in depressive and anxious symptoms measured with semi-structured psychiatric interview and Screen for Child Anxiety Related Disorders; acute mental health crises measured by urgent medical (including ED) visits; family communication measured with Conflict Behaviour Questionnaire, functional impairment measured by Columbia Impairment Scale; cost effectiveness, and fidelity of implementation measured by audio recording and fidelity checklist.DiscussionResults of this study will inform a larger multi-centre RCT that will include both community and academic hospitals in urban and rural settings. Study results will be shared at international psychiatry and emergency medicine meetings, in local rounds, and via publication in academic journals and clinician-oriented newsletters. If effective, the intervention may provide a brief, scalable, and transportable treatment program that may be implemented in a variety of settings, including those in which access to children’s mental health care services is challenging.Trial registrationClinicalTrials.gov: NCT03488602, retrospectively registered April 4, 2018.

Design features of screw propellers of icebreakers and ice navigation vessels

Представлены обобщенные результаты доковых осмотров судов Дальневосточного морского бассейна. Приведены примеры и выполнен анализ характерных повреждений гребных винтов ледоколов и судов ледового плавания, а также условий, при которых они были получены. Рассмотрены требования Российского морского регистра судоходства (РС) к проектированию ледовых гребных винтов, характеристика возможных нагрузок на их лопасти. Приведен пример расчета усталостной прочности винтов ледокола с учетом рекомендаций РС и Шведско-финских правил для судов ледового плавания (Finnish-Swedish Ice Class Rules). This paper covers summarized results of dock inspections of vessels in the Far Eastern Sea Basin. Examples of typical damages of screw propellers of icebreakers and ice navigation vessels as well as critical conditions are duly presented. Requirements of the Russian Maritime Register of Shipping (RMRS) for the design of ice propellers and parameters of active loads for their blades are fully considered. The example of fatigue strength calculation of icebreaker propeller is given subject to the requirements by RMRS and Finnish-Swedish Ice Class Rules.