This paper addresses the scheduling problem that popular data parallel programming systems such as DryadLINQ and MapReduce are facing today. Designing a cluster system in a multi-user environment is challenging because cluster schedulers must satisfy multiple, possibly conflicting, enterprise goals and policies. Particularly for these new types of data-intensive applications, it continues to be a challenge to simultaneously achieve both high throughput and predictable end-to-end performance for jobs (e.g., predictable start/end times). The conventional approach of scheduling these types of jobs is to attempt to determine a best mapping between a task and a node before the job executes, and the scheduling system ceases to be involved for a given job once the job starts executing. Instead, as described in this paper, we define a reactive containment and control mechanism for scheduling and executing distributed tasks, schedule the jobs, and then continually monitor and adjust resources as the job executes. More specifically, a DryadLINQ task in our system is contained in virtual machine and distributed controllers regulate progress of the task at runtime. Using online, feedback-controlled VM CPU scheduling, our system provides a job a capability to speed-up or slow-down progress of concurrent sub-tasks so that the job can make predictable progress while sharing system resources with other jobs. The new capability allows an enterprise to enforce flexible scheduling policies such as fair-share and/or prioritizing jobs. Our evaluation results using five well-known DryadLINQ applications show the implemented distributed controllers achieve high throughput as well as predictable end-to-end performance.
Background: Three-dimensionally printed titanium (3D-Ti) cages can be divided into 2 types: window-type cages, which have a void for bone graft, and non-window-type cages without a void. Few studies have investigated the necessity of a void for bone graft in fusion surgery. Therefore, the present study assessed the clinical and radiographic outcomes of window and non-window-type 3D-Ti cages in single-level posterior lumbar interbody fusion. Methods: A total of 70 patients were randomly assigned to receive either a window or non-window cage; 61 patients (87%) completed final follow-up (32 from the window cage group, 29 from the non-window cage group). Radiographic outcomes, including fusion rates, subsidence, and intra-cage osseointegration patterns, were assessed. Intra-cage osseointegration was measured using the intra-cage bridging bone score for the window cage group and the surface osseointegration ratio score for the non-window cage group. Additionally, we looked for the presence of the trabecular bone remodeling (TBR) sign on computed tomography (CT) images. Results: Of the 61 patients, 58 achieved interbody fusion, resulting in a 95.1% fusion rate. The fusion rate in the non-window cage group was comparable to, and not significantly different from, that in the window cage group (96.6% and 93.8%, p > 0.99). The subsidence rate showed no significant difference between the window and non-window cage groups (15.6% and 3.4%, respectively; p = 0.262). The intra-cage osseointegration scores showed a significant difference between the groups (p = 0.007), with the non-window cage group having a higher proportion of cases with a score of 4 compared with the window cage group. The TBR sign was observed in 87.9% of patients who achieved interbody fusion, with a higher rate in the non-window cage group across the entire cohort although the difference was not significant (89.7% versus 78.1%, p = 0.385). Conclusions: Non-window-type 3D-Ti cages showed equivalent clinical outcomes compared with window-type cages and comparable interbody fusion rates. These results suggest that the potential advantages of 3D-Ti cages could be optimized in the absence of a void for bone graft by providing a larger contact surface for osseointegration. Level of Evidence: Therapeutic Level II . See Instructions for Authors for a complete description of levels of evidence.
Abstract Injecting recombinant human bone morphogenetic protein-2 (rhBMP-2) into the uppermost instrumented vertebra (UIV) during surgery to increase the bone for adult spinal deformity (ASD) is expected to be protective against the development of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). The 25 patients from study group had received 0.5 mg rhBMP-2 mixed with 1.5 g β-tricalcium phosphate paste injection into the UIV during surgery. The control group consisted of 75 age and sex matched patients who underwent surgery immediately before the start of the study. The incidences of PJK and PJF were analyzed as primary outcomes. Spinopelvic parameters and patient-reported outcomes were analyzed as secondary outcomes. Hounsfield unit (HU) measurements were performed to confirm the effect of rhBMP-2 on bone formation at preoperative and postoperative computed tomography (CT). PJK and PJF was more occurred in control group than study group (p = 0.02, 0.29, respectively). The HU of the UIV significantly increased 6 months after surgery. And the increment at the UIV was also significantly greater than that at the UIV-1 6 months after surgery. Injection of rhBMP-2 with TCP into the UIV reduced PJK and PJF rates 6 months after surgery with new bone formation.
To investigate differences in clinical features based on magnetic resonance imaging (MRI) in idiopathic isolated optic neuritis patients. We retrospectively analyzed 68 eyes of 59 patients diagnosed with optic neuritis and showed inflammatory findings indicative of optic neuritis on MRI. We investigated clinical features, such as the presence of accompanying pain, visual acuity, and optic disc swelling. Optic disc swelling was classified as normal, mild, or severe. The MRI results were divided into intraorbital, intracanalicular, and whole optic nerve according to the lesion, and these were compared and analyzed with clinical features. The study included 29 men and 30 women, with a mean age of 42.6 ± 16.6 years. Among 59 patients, 48 (81.4%) complained of pain. Optic disc swelling was not observed in 48.5% of patients (33 eyes). Inflammatory changes were the most common in the intraorbital region (33 eyes), intracanalicular region (20 eyes), and the entire optic nerve (15 eyes). There was no statistical difference in the pain pattern according to the location of the lesion (p = .677), but when inflammation was present in the entire optic nerve, optic disc swelling was severe (p = .023). The initial and final visual acuity did not significantly correlate with the MRI pattern, presence of pain, or optic disc swelling (p = .156, p = .714, and p = .436). The MRI contrast enhancement pattern was associated with optic disc swelling but was not associated with pain or initial visual acuity. It should be noted that it is insufficient to judge the clinical features of optic neuritis based on MRI findings.
Recent studies on biportal endoscopic spine surgery in patients with lumbar spinal stenosis have reported good clinical results. However, these studies have been limited by the small sample sizes and use of a retrospective study design. Therefore, we aim to compare the efficacy and safety of biportal endoscopic decompressive laminectomy with those of conventional decompressive laminectomy in a multicenter, prospective, randomized controlled trial.This study will include 120 patients (60 per group, aged 20-80 years) with 1- or 2-level lumbar spinal stenosis, who will be recruited from six hospitals. The study will be conducted from July 2021 to December 2024. The primary outcome (Oswestry Disability Index at 12 months after surgery) will be evaluated through a modified intention-to-treat method. The secondary outcomes will include the following: visual analog scale score for low back and lower extremity radiating pain, EuroQol 5-dimensions score, surgery satisfaction, walking time, postoperative return to daily life period, postoperative surgical scars, and some surgery-related variables. Radiographic outcomes will be analyzed using magnetic resonance imaging or computed tomography. All outcomes will be evaluated before the surgery and at 2 weeks, 3 months, 6 months, and 12 months postoperatively. This protocol adheres to the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines for reporting of clinical trial protocols.It is hypothesized that the efficacy and safety of biportal endoscopic and conventional decompressive laminectomy will be comparable in patients with lumbar spinal stenosis. The results of this trial will provide a high level of evidence for the efficacy and safety of the biportal endoscopic technique in patients with lumbar spinal stenosis and facilitate the development of clinical practice guidelines. Furthermore, the results of this study may indicate the feasibility of the biportal endoscopic technique for other types of spinal surgery.The ENDO-B trial is registered at Clinical Research Information Service (CRIS, cris.nih.go.kr ) (KCT0006057; April 52,021).
Study Design. A retrospective cohort, radiographic study. Objective. To assess the diagnostic accuracy of bone scintigraphy (BS) for the detection of cervical spine metastases in oncological patients. Summary of Background Data. BS remains the modality of choice for the screening of bone metastases, because of its feasibility in whole-body scanning and its widespread availability at low cost. Current practice guidelines for patients with malignant diseases recommend BS imaging as the primary screening method for detecting both axial and appendicular skeletal metastases. Methods. Of 481 patients, 242 were diagnosed with cervical spinal metastases from a primary cancer. The BS findings of these patients, evaluated by nuclear medicine physicians, were assessed with respect to their usefulness for detecting cervical spine metastases. Magnetic resonance imaging findings, evaluated by radiologists, were used as the reference standards. The diagnostic value of BS was compared between subgroups according to the order in which the diagnostic procedures (magnetic resonance imaging and BS) were completed, the presence of pathological fractures, the location of the primary malignancy, and the number of cervical metastases. Results. The sensitivity of BS in the detection of cervical spine metastases was 59.1%, with a 40.9% rate of false-negative diagnoses; the specificity was 94.6%, with a 5.4% rate of false-positive diagnoses. The sensitivity tended to be higher in the presence of pathological fractures (72.1% in cases with a fracture vs. 3% in cases without a fracture) and a greater number of lesions (r = 0.921). Neither the order in which the diagnostic examinations were performed nor the location of the primary cancer, except for those in the stomach and liver, appeared to affect the diagnostic accuracy of BS. Conclusion. Considering the moderately high false-negative diagnostic rate obtained in the present study, BS alone cannot accurately diagnose metastases in the cervical spine in oncological patients. Level of Evidence: 3
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