Standard Frame Research Articles

Effect of Electrical Steel Punching on the Performance of Fractional-kW Electrical Machines

The effect of electrical steel degradation due to punching on the performance of fractional-kW electrical machines in terms of torque and iron losses is investigated. The local degradation of the steel is considered in the BH curve and iron losses model by continuous variation of the magnetic proprieties as a function of the distance from the cut edges. The newly introduced parameters are identified by fitting the proposed relations for the BH curve and iron losses with measured values obtained via standard Epstein frame test. The position-dependent BH curve is incorporated into magnetostatic FE equations. Then, the performance of two different synchronous machines, i.e. with permanent magnets and reluctance rotor, is analyzed by means of FE simulations. Considering punching, the average torque decreases by 0.5-2 %, while the iron losses can undergo an increase of 30-40 %. Moreover, in order to check the validity of the model, the magnetic friction torque of two permanent-magnet motors, one with an annealed stator and the other one with a non-annealed stator, is measured and compared with calculated values based on the FE model

Effect of Winding Design on the Performance of Predictive Current Control of Six-Phase Induction Machine-Based Propulsion Systems

Electric propulsion based on six-phase machines in marine propulsion and automotive traction applications are undergoing rapid development due to its high capacity, fault tolerance, reduced size, and reduced torque pulsations. Among different control techniques of six-phase machines, direct controllers, such as finite control set model predictive control (FCS-MPC), have extensively been studied in recent literature. One of the main problems of this controller type is the relatively poor current quality due to circulating <i>xy</i> current components. This problem has been tackled in literature through enhanced control techniques and/or winding design. Following both approaches, this paper extends a previous study to deeply investigate the effect of winding design on the performance of the model predictive control applied to a six-phase induction machine (SPIM). Three six-phase winding layouts have been compared, namely, dual-three phase (D3P), asymmetrical (A6P) and symmetrical (S6P) configurations. The main objective of this study is to investigate the effect of winding chording when standard three-phase stator frames are employed on the current quality of different winding configurations under classical predictive current control (PCC). A 1.5Hp prototype system has been used for this experimental comparative study.

Compression of A Midfoot Osteotomy Using A Circular External Fixator: What is the Ideal Pin Configuration?

Category:Midfoot/Forefoot; Diabetes; TraumaIntroduction/Purpose:Foot and ankle deformity correction through midfoot osteotomy can be implemented in a wide variety of clinical situations. Use of a circular ring fixator for osteotomy fixation is particularly useful for patients with poor soft tissue envelopes and/or active infection as can occur in diabetes and Charcot arthropathy. The foot pins in a ring fixator can be configured to apply compression at the osteotomy site. However, the optimal pin configuration and force has yet to be determined. The purpose of this study was to quantify compressive forces achieved across midfoot osteotomies with various wire configurations in a circular ring fixator construct.Methods:Nine through-knee amputation cadavers were stabilized with a standard circular external fixation carbon frame. A midfoot osteotomy through the transverse tarsal joint was performed using an oscillating saw. A 4mm bone wedge was removed from the osteotomy site for placement of a Tekscan pressure sensor. A two-ring frame was applied in the standard fashion and three parallel 1.8mm smooth wires were placed parallel to each other through the foot distal to the osteotomy: wire #1 proximally through the cuneiforms, wire #2 through the base of the metatarsals, wire #3 through the metatarsal shafts. After baseline pressure readings, wires were sequentially attached (wire #1 alone, wire #1-2, wire #1-3) to the ring fixator and tensioned to 90kg. Pressure readings were recorded at the osteotomy site for each sequential wire tensioning both at the hole location where the wire naturally crossed, 'neutral', and again at one hole 'proximal' (e.g., toward the osteotomy).Results:Average compressive load at neutral hole positioning for wire #1 was 382 N. The addition of wire #2 increased the compressive load to 439 N on average. The addition of wire #3 decreased compressive force to 372 N. Similar trends were seen in proximal hole positioning where average compressive force increased following tensioning of wire #2 from 580 N to 600 N but compressive force decreased on wire #3 addition to 425 N. Therefore, tensioning forefoot thin wires in the proximal hole position increases compressive forces by 50% compared to neutral position, and adding a second wire increased compressive force by up to 15% compared to a single forefoot wire.Conclusion:In a circular frame midfoot fusion model, the greatest compressive force was achieved with two wires tensioned in the proximal hole position. The addition of a third wire led to force decrease likely due to off-axis forces that may distract the osteotomy site given the difficulty of passing all wires perfectly parallel in all planes. Ideal positioning and tensioning of forefoot pins may optimize construct stability and compression and improve healing of the midfoot osteotomy.

Multiphase Stator Winding: New Perspectives, Advanced Topologies, and Futuristic Applications

Multiphase winding configurations have gained significant attention in high-performance variable speed drives and wind energy conversion systems (WECS) owing to their myriad advantages. In the available literature, various multiphase winding layouts have been designed aiming at boosting the machine performance to meet the requirements of the proposed applications. Ultimately, this paper surveyed the state-of-the-art in the available multiphase winding layouts proposed for various innovative applications. Various types of windings were discussed, while investigating their advantages and limitations. This typically considers the winding layouts employed in multiphase induction motors (IMs) and permanent magnet (PM) machines with prime phase and multiple three-phase orders. This study extensively provides innovative winding arrangements that offer better machine characteristics in terms of torque density, efficiency, and fault-tolerance capability. Moreover, the construction of multiphase machines with general <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> -phase using standard three-phase stator frames has been elaborated. This latter technique obviates the basic necessity of special stator frames with a prime number of phases. Finally, this paper sheds light on the commercial applications that include multiphase winding layouts.

On the two genetically related jātakastavas from Lalitavistara and Rāṣṭrapālaparipṛcchā-sūtra

This paper examines two poetic fragments from two Buddhist texts: one – from Lalitavistara and another – from Rāṣṭrapālaparipṛcchā-sūtra. As the study reveals, both passages demonstrate certain genre characteristics that allow considering them as samples of jātakastava (lit. “jātaka-praise”). This genre is represented by only two extant separate poems. However, one can also find poetic passages with similar characteristics in several voluminous Buddhist monuments. Jātakastava is a type of poem consisting of the frame and the main part. The frame has much in common with standard frames of ancient and medieval Indian religious hymns – in it, the author of the poem tells us that he is not talented enough to describe the deeds of the Buddha himself, and informs us about the benefits that one can get by reading and distributing the work. The main part of the poem describes the deeds of the Buddha performed by him in his previous births. Both of the passages under consideration demonstrate a number of similarities in the content as well as in the form. This allows us to make an assumption about a common source of origin for them. Having determined the genetic relationship of the two texts, we proceed to analyze the composition of large poetic fragments, which include the verses in question. It appears that individual stanzas of the poems, getting inside a large Buddhist text, could scatter, find a new place for themselves, obeying the structure that underlies the corresponding passages of newly created or expanded monuments.

Climate Justice and Informal Representation.

What would constitute just representation for the climate vulnerable? My purpose in this essay is to provide a critique of the default frame for approaching this question, as well as to offer a suggestion for expanding our conception of what an adequate answer should include. The standard frame conceives of representing vulnerable climate interests largely in terms of formal mechanisms of representation in technocratic and bureaucratic institutions. I show the limits of that standard approach and caution against the discussion of climate representation being overly confined to the level of "formal" representation. I go on to detail the importance of thinking about more "informal" modes of representing vulnerable climate interests. In order to pursue both of these aims, I draw on lessons in meaningful representation and inclusion during postconflict peacebuilding.

Regular Frames for Spherically Symmetric Black Holes Revisited

We consider a space-time of a spherically symmetric black hole with one simple horizon. As a standard coordinate frame fails in its vicinity, this requires continuation across the horizon and constructing frames which are regular there. Up to now, several standard frames of such a kind are known. It was shown in the literature before, how some of them can be united in one picture as different limits of a general scheme. However, some types of frames (the Kruskal–Szekeres and Lemaître ones) and transformations to them from the original one remained completely disjoint. We show that the Kruskal–Szekeres and Lemaître frames stem from the same root. Overall, our approach in some sense completes the procedure and gives the most general scheme. We relate the parameter of transformation e0 to the specific energy of fiducial observers and show that in the limit e0→0, a homogeneous metric under the horizon can be obtained by a smooth limiting transition.

Common Worlding Pedagogies: Opening Up to Learning with Worlds

Common worlding is a collective pedagogical approach. It is also a deliberate move to open up education to worlds beyond narrow human preoccupations and concerns and beyond its standard framing as an exclusively social practice. In this article, we identify some of the guiding principles that underpin this approach and explain how they work out in practice. We do so by offering a selection of illustrative vignettes drawn from the Walking with Wildlife in Wild Weather Times early childhood research project in Canberra, Australia, and from the Witnessing the Ruins of Progress early childhood research collaboratory in Ontario, Canada.

Randomized Signal Processing with Continuous Frames

This paper focuses on signal processing tasks in which the signal is transformed from the signal space to a higher dimensional coefficient space (also called phase space) using a continuous frame, processed in the coefficient space, and synthesized to an output signal. We show how to approximate such methods, termed phase space signal processing methods, using a Monte Carlo method. As opposed to standard discretizations of continuous frames, based on sampling discrete frames from the continuous system, the proposed Monte Carlo method is directly a quadrature approximation of the continuous frame. We show that the Monte Carlo method allows working with highly redundant continuous frames, since the number of samples required for a certain accuracy is proportional to the dimension of the signal space, and not to the dimension of the phase space. Moreover, even though the continuous frame is highly redundant, the Monte Carlo samples are spread uniformly, and hence represent the coefficient space more faithfully than standard frame discretizations.

Censoring Extremism: Influence of Online Restriction on Official Media Products of ISIS

ABSTRACT Recognizing that militant, non-state groups utilize social media and online platforms to reach members, sympathizers, and potential recruits, state agencies and social media corporations now increasingly regulate access to accounts affiliated with such groups. Scholars examining deplatforming efforts have, to date, focused on the extent of audience loss after account restrictions and the identification of strategies for regrouping online followers on the same or different platforms over time. Left unexplored is if and how militant non-state groups adapt their official messaging strategies in response to platform restrictions despite continuing online access to them. To begin to fill that gap, this study compares ISIS’s 550 images displayed in the group’s official newsletter al-Naba 6 months before and after Europol’s November 2019 take-down of terrorist affiliated accounts, groups, channels, and bots on Telegram. It conducts a content analysis of images related to militaries and their outcomes, non-military activities and their outcomes, and presentational forms. The findings demonstrate that ISIS visually emphasizes its standard priming approach but shifts its agenda-setting strategy. While retaining some of its standard visual framing practices, the group also alters frames, particularly those related to images showing opposing militaries and military outcome.

Egocentric video summarisation via purpose-oriented frame scoring and selection

Existing video summarisation techniques are quite generic in nature, since they generally overlook the important aspect of what actual purpose the summary will be serving. In sharp contrast with this mainstream work, it can be acknowledged that there are many possible purposes the same videos can be summarised for. Accordingly, we consider a novel perspective: summaries with a purpose. This work is an attempt to both, call the attention on this neglected aspect of video summarisation research, and to illustrate it and explore it with two concrete purposes, focusing on first-person-view videos. The proposed purpose-oriented summarisation techniques are framed under the common (frame-level) scoring and selection paradigm, and have been tested on two egocentric datasets, BEOID and EGTEA-Gaze+. The necessary purpose-specific evaluation metrics are also introduced.The proposed approach is compared with two purpose-agnostic summarisation baselines. On the one hand, a partially agnostic method uses the scores obtained by the proposed approach, but follows a standard generic frame selection technique. On the other hand, the fully agnostic method do not use any purpose-based information, and relies on generic concepts such as diversity and representativeness. The results of the experimental work show that the proposed approaches compare favourably with respect to both baselines. More specifically, the purpose-specific approach generally produces summaries with the best compromise between summary lengths and favourable purpose-specific metrics. Interestingly, it is also observed that results of the partially-agnostic baseline tend to be better than those of the fully-agnostic one. These observations provide strong evidence on the advantage and relevance of purpose-specific summarisation techniques and evaluation metrics, and encourage further work on this important subject.

Percutaneous Dilational Tracheostomy at the Epicenter of the SARS-CoV-2 Pandemic: Impact on Critical Care Resource Utilization and Early Outcomes.

The COVID-19 pandemic overwhelmed New York City hospitals early in the pandemic. Shortages of ventilators and sedatives prompted tracheostomy earlier than recommended by professional societies. This study evaluates the impact of percutaneous dilational tracheostomy (PDT) in COVID+ patients on critical care capacity. This is a single-institution prospective case series of mechanically ventilated COVID-19 patients undergoing PDT from April 1 to June 4, 2020 at a public tertiary care center. Fifty-five patients met PDT criteria and underwent PDT at a median of 13days (IQR 10, 18) from intubation. Patient characteristics are found in Table 1. Intravenous midazolam, fentanyl, and cisatracurium equivalents were significantly reduced 48hours post-PDT (Table 2). Thirty-five patients were transferred from the ICU and liberated from the ventilator. Median time from PDT to ventilator liberation and ICU discharge was 10 (IQR 4, 14) and 12 (IQR 8, 17)days, respectively. Decannulation occurred in 45.5% and 52.7% were discharged from acute inpatient care (Figure 1). Median follow-up for the study was 62days. Four patients had bleeding complications postoperatively and 11 died during the study period. Older age was associated with increased odds of complication (OR 1.12, 95% CI 1.04, 1.23) and death (OR=1.15, 95% CI 1.05, 1.30). All operators tested negative for COVID-19 during the study period. These findings suggest COVID-19 patients undergoing tracheostomy within the standard time frame can improve critical care capacity in areas strained by the pandemic with low risk to operators. Long-term outcomes after PDT deserve further study.

Effect of Parathyroid Hormone Level within One Hour of Total Thyroidectomy on Serum Calcium Level

Background: Parathyroid dysfunction leading to symptomatic hypocalcemia is not uncommon following a total or completion thyroidectomy and is often associated with significant patient morbidity and a prolonged hospital stay. The current study is designed to evaluate the role of parathormone (PTH) levels detected in a standard time frame after total thyroidectomy as a predictor of post-thyroidectomy hypocalcemia. Objectives: To investigate whether postoperative parathyroid hormone level is a parameter to identify hypocalcemia after total thyroidectomy as well as to find out the optimum cut-off value of parathyroid hormone in early postoperative period. Methodology: This was a cross-sectional study. A total of 103 patients’ male-female with a variety of thyroid disorders with an indication of total thyroidectomy attended the outpatient department and inpatient department of Surgery and Otolaryngology, BSMMU. This study was carried out from March 2018 to September 2019. The routine clinical assessment and the preoperative laboratory investigations were performed before operation. Preoperative levels of serum PTH were measured. Statistical analysis was carried out using SPSS version.22.0. Results: The levels of PTH in the immediate postoperative period showed that 17(16.50%) patients belonged to low PTH (&lt;14). The mean PTH in immediate post-operative was 36.79±21.71 with a range from 0.2 to 111.3. Regarding the distribution of the study patients by serum calcium, it was observed that 20.39% of patients belonged to low (&lt;8 mg/dl) serum calcium. The mean serum calcium level was 8.47±1.19 with ranging from 2.1 to 10.6. In the current study, the scatter diagram showed a positive significant correlation (r=0.310; p=0.001) between PTH and S. Calcium immediate post-operative period. ROC curve for finding the cut-off value of PTH in the immediate post-operative period to predict hypocalcemia among the study population. Conclusion: Hypocalcaemia after the total or completion ....

Numerical modeling of magnetic induction in standard and triple Epstein frames considering cutting and staggering of sensor strips

For magnetic energy loss measurements on electric steel sheets, the Epstein tester (ET) is applied for 100 years. However, it suffers from unsolved problems, such as inhomogeneity of flux in the corners and even more of impact of sample cutting. As a matter of fact, a detailed study of flux distributions—as a pre-condition for improvements—has not been performed so far. In this work, we present the results of an advanced numerical 3D-magnetic anisotropic circuit calculation modeling. It considers most relevant impacts such as anisotropy, non-linearity, method of staggering, and in particular, consequences of sample cutting. According to the literature, the latter may yield material deterioration for edge zones of high width WDET. Here, we set WDET to 2.5 mm as a “coarse-cut” convention for practice, and we compare it with perfect “fine-cut” (W = 0). As a main result, deteriorated edge zones of standard ET strips of low width W = 30 mm yield a distinct concentration of flux along inner axial strip regions as a reason for strong local flux inhomogeneity and distortion. Consistent numerical comparisons predict that higher grades of magnetic homogeneity can be expected from wider sample strips, e.g., from a “Triple ET” with W = 90 mm. As a global conclusion, the Epstein frame represents a system of extreme 3D inhomogeneity, especially in the corners. The grade of inhomogeneity reaches its maximum in instants of high permeability. It may be strongly increased through coarse cutting. On the other hand, consequences of cutting can be decreased by increasing the strip width. This would allow for loss measurements using tangential field coils arranged in the central limb regions of TET.

865 Reducing Delays in Cholecystectomy Surgery of Patients Admitted with Gallstone-Related Disease Within Gold Standard Time Frame Set Out By NICE

Abstract Introduction As per NICE guidelines, Cholecystectomy Quality Improvement Collaborative (Chole-QuIC) aims for 80% of eligible patients with gallstone-related disease to receive their cholecystectomy within 8 days of presentation1. Only 63.6% of eligible patients at East Lancashire Hospitals NHS Trust (ELHT) had their surgery within the target time. This project was done to identify the reasons behind ELHT not achieving the set target and to implement changes to overcome this. Method This was a retrospective review of a prospectively collected data of 444 patients from the ELHT Chole-QuIC database (July 2019-November 2020). Data were analysed in three periods: initial period (July 2019-November 2019), pre-COVID-19 period (December 2019-February 2020), COVID-19 period (March 2020-November 2020). Time to surgery was established. If the 8-day target was not met, reasons behind the delay were recorded. Results During the first cycle, the main reasons delays included the patients being temporarily unfit (13.8%), insufficient theatre capacity (13.8%) and variations in treatment plans (11.32%). 8% of patients had re-admissions related to their gallstone disease. Changes were implemented forward included a clear local gallstone disease management pathway and CholeQuIC referral system, increasing theatre capacity, and allocating pre-operative assessment slots. Gold standard cholecystectomy target period improved from 63.6% to 67.4% within three months of changes. However, the figure drastically reduced during the COVID-19 pandemic (36.3%) as elective surgeries were temporarily suspended. Conclusions The implementation of a gallstone disease management pathway, a coordinated referral system and additional theatre capacity contributed to the increase in cholecystectomies that were performed within the 8-day national target period.

Affordable stereotactic-guided focused ultrasound device for tunable drug delivery to the mouse brain

Focused ultrasound combined with microbubble (FUS+MB)-mediated blood brain barrier (BBB) opening is not only a promising technique for clinical applications but also a powerful tool for preclinical neuroscience and neuro-oncology research. However, existing FUS systems are expensive and lack the flexibility of modulating BBB opening volume, which prevents a broader research community from adopting the FUS+MB technique in preclinical studies. To address the challenge, we developed a low cost (∼$100), mini FUS transducer with the capability to modulate BBB opening size that can be readily integrated with a standard stereotaxic frame for mouse. Specifically, we manufactured in-house mini FUS transducers with three frequencies (1.5, 3.0, and 6.0 MHz), and quantified BBB opening and targeting accuracy at varying pressures (0.20 to 0.81 MPa). The volume of FUS+MB-induced BBB opening was evaluated using both contrast-enhanced MRI and Evans blue extravasation. Our results showed that we can achieve varying amount of Evans blue delivery and BBB opening size by modulating the transducer frequency and acoustic pressure. Additionally, the amount of Evans blue delivery and BBB opening had a significant linear correlation with the cavitation index (defined by the ratio between acoustic pressure and frequency). We believe that this stereotaxic-guided FUS system will lower the barrier for adopting the FUS technique in a broader research community.

Multi object tracking using gradient-based learning model in video-surveillance

On accomplishing an efficacious object tracking, the activity of an object concerned becomes notified in a forthright manner. An accurate form of object tracking task necessitates a robust object tracking procedures irrespective of hardware assistance. Such approaches inferred a vast computational complexity to track an object with high accuracy in a stipulated amount of processing time. On the other hand, the tracking gets affected owing to the existence of varied quality diminishing factors such as occlusion, illumination changes, shadows etc., In order to rectify all these inadequacies in tracking an object, a novel background normalization procedure articulated on the basis of a textural pattern is proposed in this paper. After preprocessing an acquired image, employment of an Environmental Succession Prediction algorithm for discriminating disparate background environment by background clustering approach have been accomplished. Afterward, abstract textural characterizations through utilization of a Probability based Gradient Pattern (PGP) approach for recognizing the similarity between patterns obtained so far. Comparison between standardized frame obtained in prior and those processed patterns detects the motion exposed by an object and the object concerned gets identified within a blob. Hence, the system is resistant towards illumination variations. These illumination variation was interpreted in object tracking residing within a dynamic background. Devised approach certainly outperforms other object tracking methodologies like Group Target Tracking (GTT), ViPER-GT, grabcut, snakes in terms of accuracy and average time. Proposed PGP-based pattern texture analysis is compared with Gamifying Video Object (GVO) approach and hence, it evidently outperforms in terms of precision, recall and F1 measure.

Flexural and compressive behaviour of I steel section strengthened by stainless steel plate

Because of its great mechanical, durability, and aesthetic features, stainless steel is commonly utilised in construction. Stainless steel is likely to become increasingly widely specified in the building of sustainable infrastructure. This research looks at the experimental and analytical study of the flexural and compressive behaviour of steel sections strengthened with duplex stainless steel. The ISMB125 section is arc welded using duplex stainless steel plate of various thicknesses and lengths. Using a standard loading frame test, a standard 3-point bending and axial compressive test is performed, with the results revealing the load–displacement, ultimate load, stress, and strain. Following the experimental research, all of the specimens were analysed using the finite element method in ANSYS, with the results compared to those obtained experimentally. The optimal length and thickness of stainless steel plates for strengthening steel beams and columns are determined.

Can citizen pressure influence politicians' communication about climate change? Results from a field experiment.

Urgent reductions in greenhouse gas emissions depend on governments implementing and enforcing rigorous climate policy. Individuals in democracies seeking to persuade government officials to reduce greenhouse gas emissions can take steps such as voting, protesting, and contacting officials directly, but it is unclear how effective each of these actions is in changing the behavior of elected officials. Here we take advantage of the public nature of social media to evaluate the actual efficacy of climate campaign emails using an original, real-world experiment where 335 Members of Canadian Parliament were asked by constituents to post a pro-climate message to their Twitter account. Only one Member of Parliament posted the exact text suggested by the campaign. After scraping and coding 18,776 tweets, we first find no evidence that a public health messaging frame is more effective than a standard environmental frame in eliciting pro-climate posts. Furthermore, we find only a marginally significant relationship between volume of constituent contact and increased pro-climate tweeting from Members of Parliament. Follow-up interviews with political staffers suggest that analog alternatives may be more effective than campaign emails in some cases. Interview findings also reveal that some offices receive low levels of constituent communication on climate change, indicating that increased pressure from constituents could still be consequential.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10584-021-03215-9.

148. Sacroiliac joint fusion navigation: how accurate is pin placement?

BACKGROUND CONTEXT Percutaneous pin placement is used in a variety of orthopedic surgery settings. These include, but are not limited to, external fixator placement, fracture fixation, and reference frame application for navigation. Although pin placement typically is uncomplicated, it can become more difficult with the need for obliquely angled pins and the potential for the pin to slip off the bone. For spine and pelvic cases with intraoperative navigation, often a standard reference frame is placed using a percutaneous pin. The goal is for this pin to be placed into the posterior ilium, which is an oblique surface. Proper placement of this pin helps to ensure the correct placement of the sacroiliac joint (SIJ) fusion implants. To date, there is no literature specifically examining the accuracy of pin placement. PURPOSE The purpose of our study was to evaluate the occurrence of ideal percutaneous pin placement into the iliac wing during navigated SIJ fusion surgery. STUDY DESIGN/SETTING IRB approved retrospective chart review study completed at an academic medical institution. PATIENT SAMPLE Patients who underwent navigated SIJ fusion by the senior author between 10/2013 and 1/2020. OUTCOME MEASURES Pin placement accuracy graded in concordance with a scheme developed and tested by the authors. METHODS Following IRB approval, we reviewed the charts and intraoperative CT imaging of patients who underwent navigated SIJ fusion by the senior author between 10/2013 and 1/2020. A pin placement grading scheme was developed initially and tested. The definition of ‘ideal’ placement was a concept developed by the authors. A modification was made and found to be acceptable to attending surgeons. This was then used for two rounds of grading. Six attending surgeons completed two rounds of pin placement grading. RESULTS Of the 95 eligible patients, 54.7% had ‘ideal’ pin placement. There were no observed complications from pin placement. There was no relationship between BMI and ideal placement. Male patients were 3.6 times more likely to have ideal placement than females. Additionally, patients undergoing right-sided fusion were 2.9 times more likely to have ideal placement than those with left-sided fusion. Interobserver reliability was rated as 0.48 and 0.47 in the first and second rounds defined as ‘moderate agreement.’ The measured intraobserver reliability ranged from 0.62 to 0.74 defined as ‘substantial agreement.’ Conclusions This study shows that even in the hands of an experienced surgeon, nonideal pin placement occurs 45.3% of the time. However, engagement of the lateral or medial cortex may make the pin more rigid. Though pin placement does not meet our preconceived ‘ideal’, it is only rarely a true ‘miss’ where it is placed into the sacrum. Male patients and patients undergoing right-sided fusion were more likely to have ‘ideal’ pin placement. When placing percutaneous pins, regardless of the location, it is important to be aware of factors that can decrease the accuracy of pin placement. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.